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+The Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Dragons of the Air
+       An Account of Extinct Flying Reptiles
+
+Author: H. G. Seeley
+
+Release Date: February 18, 2011 [EBook #35316]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK DRAGONS OF THE AIR ***
+
+
+
+
+Produced by Chris Curnow and the Online Distributed
+Proofreading Team at http://www.pgdp.net (This file was
+produced from images generously made available by The
+Internet Archive)
+
+
+
+
+
+
+
+
+
+                          DRAGONS OF THE AIR
+
+
+
+
+    [Illustration: FIG. 47.  RHAMPHORHYNCHUS PHYLLUNUS
+
+    SHOWING THE PRESERVATION OF THE WING MEMBRANES
+
+    _From the Lithographic slate of Eichst�dt, Bavaria_
+
+                                                     _Frontispiece_]
+
+
+
+
+                          DRAGONS OF THE AIR
+
+                             AN ACCOUNT OF
+                        EXTINCT FLYING REPTILES
+
+                                  BY
+
+                         H. G. SEELEY, F.R.S.
+
+  PROFESSOR OF GEOLOGY IN KING'S COLLEGE, LONDON; LECTURER ON GEOLOGY
+        AND MINERALOGY IN THE ROYAL INDIAN ENGINEERING COLLEGE
+
+                       WITH EIGHTY ILLUSTRATIONS
+
+                      "I AM A BROTHER OF DRAGONS"
+                                                  _Job_ xxx. 29
+
+
+                      NEW YORK: D. APPLETON & CO.
+                        LONDON: METHUEN & CO.
+
+                                 1901
+
+
+
+
+PREFACE
+
+
+I was a student of law at a time when Sir Richard Owen was lecturing on
+Extinct Fossil Reptiles. The skill of the great master, who built bones
+together as a child builds with a box of bricks, taught me that the laws
+which determine the forms of animals were less understood at that time
+than the laws which govern the relations of men in their country. The
+laws of Nature promised a better return of new knowledge for reasonable
+study. A lecture on Flying Reptiles determined me to attempt to fathom
+the mysteries which gave new types of life to the Earth and afterwards
+took them away.
+
+Thus I became the very humble servant of the Dragons of the Air. Knowing
+but little about them I went to Cambridge, and for ten years worked with
+the Professor of Geology, the late Rev. Adam Sedgwick, LL.D., F.R.S., in
+gathering their bones from the so-called Cambridge Coprolite bed, the
+Cambridge Greensand. The bones came in thousands, battered and broken,
+but instructive as better materials might not have been. My rooms
+became filled with remains of existing birds, lizards, and mammals,
+which threw light on the astonishing collection of old bones which I
+assisted in bringing together for the University.
+
+In time I had something to say about Flying Animals which was new. The
+story was told in the theatre of the Royal Institution, in a series of
+lectures. Some of them were repeated in several English towns. There was
+still much to learn of foreign forms of flying animals; but at last,
+with the aid of the Government grant administered by the Royal Society,
+and the chiefs of the great Continental museums, I saw all the specimens
+in Europe.
+
+So I have again written out my lectures, with the aid of the latest
+discoveries, and the story of animal structure has lost nothing in
+interest as a twice-told tale. It still presents in epitome the story of
+life on the Earth. He who understands whence the Flying Reptiles came,
+how they endured, and disappeared from the Earth, has solved some of the
+greatest mysteries of life. I have only contributed something towards
+solving the problems.
+
+In telling my story, chiefly of facts in Nature, an attempt is made to
+show how a naturalist does his work, in the hope that perhaps a few
+readers will find happiness in following the workings of the laws of
+life. Such an illumination has proved to many worth seeking, a solid
+return for labour, which is not to be marketed on the Exchange, but may
+be taken freely without exhausting the treasury of Nature's truths. Such
+outlines of knowledge as here are offered to a larger public, may also,
+I believe, be acceptable to students of science and scientific men.
+
+The drawings given in illustration of the text have been made for me by
+Miss E. B. Seeley.
+
+                                                              H. G. S.
+  KENSINGTON, _May, 1901_
+
+
+
+
+CONTENTS
+
+
+                                                                    PAGE
+  CHAPTER I.
+  FLYING REPTILES                                                      1
+
+  CHAPTER II.
+  HOW A REPTILE IS KNOWN                                               4
+
+  CHAPTER III.
+  A REPTILE IS KNOWN BY ITS BONES                                     11
+
+  CHAPTER IV.
+  ANIMALS WHICH FLY                                                   15
+
+  CHAPTER V.
+  DISCOVERY OF THE PTERODACTYLE                                       27
+
+  CHAPTER VI.
+  HOW ANIMALS ARE INTERPRETED BY THEIR BONES                          37
+
+  CHAPTER VII.
+  INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS                 45
+
+  CHAPTER VIII.
+  THE PLAN OF THE SKELETON                                            58
+
+  CHAPTER IX.
+  THE BACKBONE, OR VERTEBRAL COLUMN                                   78
+
+  CHAPTER X.
+  THE HIP-GIRDLE AND HIND LIMB                                        93
+
+  CHAPTER XI.
+  SHOULDER-GIRDLE AND FORE LIMB                                      107
+
+  CHAPTER XII.
+  EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS                  134
+
+  CHAPTER XIII.
+  ANCIENT ORNITHOSAURS FROM THE LIAS                                 143
+
+  CHAPTER XIV.
+  ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS                       153
+
+  CHAPTER XV.
+  ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS                        172
+
+  CHAPTER XVI.
+  CLASSIFICATION OF THE ORNITHOSAURIA                                187
+
+  CHAPTER XVII.
+  FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM 196
+
+  CHAPTER XVIII.
+  HOW PTERODACTYLES MAY HAVE ORIGINATED                              213
+
+  APPENDIX                                                           231
+
+  INDEX                                                              233
+
+
+
+
+LIST OF ILLUSTRATIONS
+
+ FIG.                                                               PAGE
+  47. Wings of Rhamphorhynchus                            _Frontispiece_
+   1. Lung of the lung-fish Ceratodus                                  5
+   2. Attachment of the lower jaw in a Mammal and in a Pterodactyle   12
+   3. Chald�an Dragon                                                 15
+   4. Winged human figure from the Temple of Ephesus                  16
+   5. Flying fish Exocoetus                                           18
+   6. Flying Frog                                                     19
+   7. Flying Lizard (Draco)                                           20
+   8. Birds in flight                                                 22
+   9. Flying Squirrel (Pteromys)                                      24
+  10. Bats, flying and walking                                        25
+  11. Skeleton of _Pterodactylus longirostris_                        28
+  12. The skeleton restored                                           29
+  13. The animal form restored                                        30
+  14. Fore limbs in four types of mammals                             38
+  15. Pneumatic foramen in Pterodactyle bone                          46
+  16. Lungs of the bird Apteryx                                       48
+  17. Air cells in the body of an Ostrich                             49
+  18. Lung of a Chameleon                                             51
+  19. Brain in Pterodactyle, Mammal, Bird, and Reptiles               53
+  20. Skull of Kingfisher and Rhamphorhynchus                         63
+  21. Skull of Heron and Rhamphorhynchus                              65
+  22. Palate of Macrocercus and ? Campylognathus                      71
+  23. Lower jaw of Echidna and Ornithostoma                           76
+  24. First two neck vertebr� of Ornithocheirus                       81
+  25. Middle neck vertebr� of Ornithocheirus                          83
+  26. Back vertebra of Ornithocheirus and Crocodile                   86
+  27. Sacrum, with hip bones, of Rhamphorhynchus                      88
+  28. Extremity of tail of _Rhamphorhynchus phyllurus_                91
+  29. Hip-girdle bones in Apteryx and Rhamphorhynchus                 95
+  30. Pelvis with prepubic bone in Pterodactylus                      96
+  31. Pelvis with prepubic bones in Rhamphorhynchus                   97
+  32. Pelvis of an Alligator seen from below                          98
+  33. Femora: Echidna, Ornithocheirus, Ursus                         100
+  34. Tibia and fibula: Dimorphodon and Vulture                      102
+  35. Metatarsus and digits in three Pterodactyles                   104
+  36. Sternum in Cormorant and Rhamphorhynchus                       108
+  37. Sternum in Ornithocheirus                                      109
+  38. Shoulder-girdle bones in a bird and three Pterodactyles        113
+  39. The Notarium from the back of Ornithocheirus                   115
+  40. The shoulder-girdle of Ornithocheirus                          115
+  41. Humerus of Pigeon and Ornithocheirus                           119
+  42. Fore-arm of Golden Eagle and Dimorphodon                       120
+  43. Wrist bones of Ornithocheirus                                  124
+  44. Clawed digits of the hand in two Pterodactyles                 125
+  45. Claw from the hand of Ornithocheirus                           129
+  46. The hand in Arch�opteryx and the Ostrich                       130
+  48. Slab of Lias with bones of Dimorphodon          _To face page_ 143
+  49. Dimorphodon (restored form) at rest                            144
+  50. Dimorphodon (restored form of the animal)       _To face page_ 145
+  51. Dimorphodon skeleton, walking as a quadruped          "   "    146
+  52. Dimorphodon skeleton as a biped                       "   "    147
+  53. Lower jaw of Dorygnathus                                       149
+  54. Dimorphodon (wing membranes spread for flight)  _To face page_ 150
+  55. Pelvis of Dimorphodon                                          151
+  56. Rhamphorhynchus skeleton (restored)                            161
+  57. Scaphognathus (restoration of 1875)                            163
+  58. Six restorations of Ornithosaurs                               164
+  59. Ptenodracon skeleton (restored)                                167
+  60. _Cycnorhamphus suevicus_ slab with bones        _To face page_ 168
+  61. _Cycnorhamphus suevicus_ (form of the animal)   _To face page_ 169
+  62. _Cycnorhamphus suevicus_ skeleton (restored)                   170
+  63. _Cycnorhamphus Fraasi_ (restored skeleton form
+          of the animal)                              _To face page_ 170
+  64. _Cycnorhamphus Fraasi_ (restoration of the form
+          of the body)                                _To face page_ 171
+  65. Neck vertebra of Doratorhynchus from the Purbeck               173
+  66. Neck bone of Ornithodesmus from the Wealden                    173
+  67. Sternum of Ornithodesmus, seen from the front                  175
+  68. Sternum of Ornithodesmus, side view, showing the keel          175
+  69. Diagram of known parts of skull of Ornithocheirus              177
+  70. Neck bone of Ornithocheirus                                    179
+  71. Jaws of Ornithocheirus from the Chalk                          180
+  72. Palate of the English Toothless Pterodactyle                   181
+  73. Two views of the skull of Ornithostoma (Pteranodon)            182
+  74. Skeleton of Ornithostoma                                       183
+  75. Comparison of six skulls of Ornithosaurs                       192
+  76. Pelvis of Ornithostoma                                         195
+  77. Skull of Anchisaurus and Dimorphodon                           199
+  78. Skull of Ornithosuchus and Dimorphodon                         201
+  79. The pelvis in Ornithosaur and Dinosaur                         204
+  80. The prepubic bones in Dimorphodon and Iguanodon                206
+
+    These figures are greatly reduced in size, and when two or more
+    bones are shown in the same figure all are brought to the same size
+    to facilitate the comparison.
+
+
+
+
+DRAGONS OF THE AIR
+
+
+
+
+CHAPTER I
+
+FLYING REPTILES
+
+
+The history of life on the earth during the epochs of geological time
+unfolds no more wonderful discovery among types of animals which have
+become extinct than the family of fossils known as flying reptiles. Its
+coming into existence, its structure, and passing away from the living
+world are among the great mysteries of Nature.
+
+The animals are astonishing in their plan of construction. In aspect
+they are unlike birds and beasts which, in this age, hover over land and
+sea. They gather into themselves in the body of a single individual,
+structures which, at the present day, are among the most distinctive
+characters of certain mammals, birds, and reptiles.
+
+The name "flying reptile" expresses this anomaly. Its invention is due
+to the genius of the great French naturalist Cuvier, who was the first
+to realise that this extinct animal, entombed in slabs of stone, is one
+of the wonders of the world.
+
+The word "reptile" has impressed the imagination with unpleasant sound,
+even when the habits of the animals it indicates are unknown. It is
+familiarly associated with life which is reputed venomous, and is
+creeping and cold. Its common type, the serpent, in many parts of the
+world takes a yearly toll of victims from man and beast, and has become
+the representative of silent, active strength, dreaded craft, and
+danger.
+
+Science uses the word "reptile" in a more exact way, to define the
+assemblage of cold-blooded animals which in familiar description are
+separately named serpents, lizards, turtles, hatteria, and crocodiles.
+
+Turtles and the rest of them survive from great geological antiquity.
+They present from age to age diversity of aspect and habit, and in
+unexpected differences of outward proportion of the body show how the
+laws of life have preserved each animal type. For the vital organs which
+constitute each animal a reptile, and the distinctive bony structures
+with which they are associated, remain unaffected, or but little
+modified, by the animal's external change in appearance.
+
+The creeping reptile is commonly imagined as the antithesis of the bird.
+For the bird overcomes the forces that hold even man to the earth, and
+enjoys exalted aerial conditions of life. Therefore the marvel is shared
+equally by learned and unlearned, that the power of flight should have
+been an endowment of animals sprung from the breed of serpents, or
+crocodiles, enabling them to move through the air as though they too
+were of a heaven-born race. The wonder would not be lessened if the
+animal were a degraded representative of a nobler type, or if it should
+be demonstrated that even beasts have advanced in the battle of life.
+The winged reptile, when compared with a bird, is not less astounding
+than the poetic conceptions in Milton's _Paradise Lost_ of degradation
+which overtakes life that once was amongst the highest. And on the other
+hand, from the point of view of the teaching of Darwin in the theories
+of modern science, we are led to ask whether a flying reptile may not be
+evidence of the physical exaltation which raises animals in the scale of
+organisation. The dominance upon the earth of flying reptiles during the
+great middle period of geological history will long engage the interest
+of those who can realise the complexity of its structure, or care to
+unravel the meaning of the procession of animal forms in successive
+geological ages which preceded the coming of man.
+
+The outer vesture of an animal counts for little in estimating the value
+of ties which bind orders of animals together, which are included in the
+larger classes of life. The kindred relationship which makes the snake
+of the same class as the tortoise is determined by the soft vital
+organs--brain, heart, lungs--which are the essentials of an animal's
+existence and control its way of life. The wonder which science weaves
+into the meaning of the word "reptile," "bird," or "mammal," is partly
+in exhibiting minor changes of character in those organs and other soft
+parts, but far more in showing that while they endure unchanged, the
+hard parts of the skeleton are modified in many ways. For the bones of
+the reptile orders stretch their affinities in one direction towards the
+skeletons of salamanders and fishes; and extend them also at the same
+time in other directions, towards birds and mammals. This mystery we may
+hope to partly unravel.
+
+
+
+
+CHAPTER II
+
+HOW A REPTILE IS KNOWN
+
+
+DEFINITION OF REPTILES BY THEIR VITAL ORGANS
+
+The relations of reptiles to other animals may be stated so as to make
+evident the characters and affinities which bind them together. Early in
+the nineteenth century naturalists included with the Reptilia the tribe
+of salamanders and frogs which are named Amphibia. The two groups have
+been separated from each other because the young of Amphibia pass
+through a tadpole stage of development. They then breathe by gills, like
+fishes, taking oxygen from the air which is suspended in water, before
+lungs are acquired which afterwards enable the animals to take oxygen
+directly from the air. The amphibian sometimes sheds the gills, and
+leaves the water to live on land. Sometimes gills and lungs are retained
+through life in the same individual. This amphibian condition of lung
+and gill being present at the same time is paralleled by a few fishes
+which still exist, like the Australian _Ceratodus_, the lung-fish, an
+ancient type of fish which belongs to early days in geological time.
+
+This metamorphosis has been held to separate the amphibian type from
+the reptile because no existing reptile develops gills or undergoes a
+metamorphosis. Yet the character may not be more important as a ground
+for classification than the community of gills and lungs in the fish and
+amphibian is ground for putting them together in one natural group. For
+although no gills are found in reptiles, birds, or mammals, the embryo
+of each in an early stage of development appears to possess gill-arches,
+and gill-clefts between them, through which gills might have been
+developed, even in the higher vertebrates, if the conditions of life had
+been favourable to such modification of structure. In their bones
+Reptiles and Amphibia have much in common. Nearly all true reptiles lay
+eggs, which are defined like those of birds by comparatively large size,
+and are contained in shells. This condition is not usual in amphibians
+or fishes. When hatched the young reptile is completely formed, the
+image of its parent, and has no need to grow a covering to its skin like
+some birds, or shed its tail like some tadpoles. The reptile is like the
+bird in freedom from important changes of form after the egg is hatched;
+and the only structure shed by both is the little horn upon the nose,
+with which the embryo breaks the shell and emerges a reptile or a bird,
+growing to maturity with small subsequent variations in the proportions
+of the body.
+
+  [Illustration: FIG. 1  LUNG OF THE FISH CERATODUS
+
+  Partly laid open to show its chambered structure (After G�nther)]
+
+
+THE REPTILE SKIN
+
+Between one class of animals and another the differences in the
+condition of the skin are more or less distinctive. In a few amphibians
+there are some bones in the skin on the under side of the body, though
+the skin is usually naked, and in frogs is said to transmit air to the
+blood, so as to exercise a respiratory function of a minor kind. This
+naked condition, so unlike the armoured skin of the true Reptilia,
+appears to have been paralleled by a number of extinct groups of fossils
+of the Secondary rocks, such as Ichthyosaurs and Plesiosaurs, which were
+aquatic, and probably also by some Dinosauria, which were terrestrial.
+
+Living reptiles are usually defended with some kind of protection to the
+skin. Among snakes and lizards the skin has commonly a covering of
+overlapping scales, usually of horny or bony texture. The tortoise and
+turtle tribe shut up the animal in a true box of bone, which is cased
+with an armour of horny plates. Crocodiles have a thick skin embedding a
+less continuous coat of mail. Thus the skin of a reptile does not at
+first suggest anything which might become an organ of flight; and its
+dermal appendages, or scales, may seem further removed from the feathers
+which ensure flying powers to the bird than from the naked skin of a
+frog.
+
+
+THE REPTILE BRAIN
+
+Although the mode of development of the young and the covering of the
+skin are conspicuous among important characters by which animals are
+classified, the brain is an organ of some importance, although of
+greater weight in the higher Vertebrata than in its lower groups.
+Reptiles have links in the mode of arrangement of the parts of their
+brains with fishes and amphibians. The regions of that organ are
+commonly arranged in pairs of nervous masses, known as (1) the olfactory
+lobes, (2) the cerebrum, behind which is the minute pineal body,
+followed by (3) the pair of optic lobes, and hindermost of all (4) the
+single mass termed the cerebellum. These parts of the brain are extended
+in longitudinal order, one behind the other in all three groups. The
+olfactory lobes of the brain in Fishes may be as large as the cerebrum;
+but among Reptiles and Amphibians they are relatively smaller, and they
+assume more of the condition found in mammals like the Hare or Mole,
+being altogether subordinate in size. And the cerebral masses begin to
+be wider and higher than the other parts of the brain, though they do
+not extend forward above the olfactory lobes, as is often seen in
+Mammals. In Crocodiles the cerebral hemispheres have a tendency to a
+broad circular form. Among Chelonian reptiles that region of the brain
+is more remarkable for height. Lizards and Ophidians both have this part
+of the brain somewhat pear-shaped, pointed in front, and elongated. The
+amphibian brain only differs from the lizard type in degree; and
+differences between lizards' and amphibian brains are less noticeable
+than between the other orders of reptiles. The reptilian brain is easily
+distinguished from that of all other animals by the position and
+proportions of its regions (see Fig. 19, p. 53).
+
+Birds have the parts of the brain formed and arranged in a way that is
+equally distinctive. The cerebral lobes are relatively large and convex,
+and deserve the descriptive name "hemispheres." They are always smooth,
+as among the lower Mammals, and extend backward so as to abut against
+the hind brain, termed the cerebellum. This junction is brought about in
+a peculiar way. The cerebral hemispheres in a bird do not extend
+backward to override the optic lobes, and hide them, as occurs among
+adult mammals, but they extend back between the optic lobes, so as to
+force them apart and push them aside, downward and backward, till they
+extend laterally beyond the junction of the cerebrum with the
+cerebellum. The brain of a Bird is never reptilian; but in the young
+Mammal the brain has a very reptilian aspect, because both have their
+parts primarily arranged in a line. Therefore the brain appears to
+determine the boundary between bird and reptile exactly.
+
+
+REPTILIAN BREATHING ORGANS
+
+The breathing organs of Birds and Reptiles which are associated with
+these different types of brain are not quite the same. The Frog has a
+cellular lung which, in the details of the minute sacs which branch and
+cluster at the terminations of the tubes, is not unlike the condition in
+a Mammal. In a mammal respiration is aided by the bellows-like action of
+the muscles connected with the ribs, which encase the cavity where the
+lungs are placed, and this structure is absent in the Frog and its
+allies. The Frog, on the other hand, has to swallow air in much the same
+way as man swallows water. The air is similarly grasped by the muscles,
+and conveyed by them downward to the lungs. Therefore a Frog keeps its
+mouth shut, and the animal dies from want of air if its mouth is open
+for a few minutes.
+
+Crocodiles commonly lie in the sun with their mouths widely open. The
+lungs in both Crocodiles and Turtles are moderately dense, traversed by
+great bronchial tubes, but do not differ essentially in plan from those
+of a Frog, though the great branches of the bronchial tubes are
+stronger, and the air chambers into which the lung is divided are
+somewhat smaller. The New Zealand Hatteria has the lungs of this
+cellular type, though rather resembling the amphibian than the
+Crocodile. The lungs during life in all these animals attain
+considerable size, the maximum dimensions being found in the terrestrial
+tortoises, which owe much of their elevated bulk to the dimensions of
+the air cells which form the lungs.
+
+The lungs of Serpents and Lizards are formed on a different plan. In
+both those groups of reptiles the dense cellular tissue is limited to
+the part of the lung which is nearest to the throat. This network of
+blood vessels and air cells extends about the principal bronchial tube
+much as in other animals, but as it extends backward the blood vessels
+become few until the _tubular_ lung appears in its hinder part, as it
+extends down the body, almost as simple in structure as the air bladder
+of a fish. Among Serpents only one of these tubular lungs is commonly
+present, and the structure has a less efficient appearance as a
+breathing organ than the single lung of the fish _Ceratodus_ (Fig. 1).
+The Chameleons are a group of lizards which differ in many ways from
+most of their nearest kindred, and the lungs, while conforming in
+general plan to the lizard type in being dense at the throat, and a
+tubular bladder in the body, give off on both sides a number of short
+lateral branches like the fingers of a glove (Fig. 18, p. 51).
+
+Thus the breathing organs of reptiles present two or three distinct
+types which have caused Serpents and Lizards to be associated in one
+group by most naturalists who have studied their anatomy; while
+Crocodiles and Chelonians represent a type of lung which is quite
+different, and in those groups has much in common. These characters of
+the breathing organs contribute to separate the cold-blooded armoured
+reptiles from the warm-blooded birds clothed with feathers, as well as
+from the warm-blooded mammals which suckle their young; for both these
+higher groups have denser and more elastic spongy lung tissue.
+
+It will be seen hereafter that many birds in the most active development
+of their breathing organs substantially revert to the condition of the
+Serpent or Chameleon in a somewhat modified way. Because, instead of
+having one great bronchial tube expanded to form a vast reservoir of air
+which can be discharged from the lung in which the reptile has
+accumulated it, the bird has the lateral branches of the bronchial tubes
+prolonged so as to pierce the walls of the lung, when its covering
+membrane expands to form many air cells, which fill much of the cavity
+of the bird's body (see Fig. 16). Thus the bird appears to combine the
+characters of such a lung as that of a Crocodile, with a condition which
+has some analogy with the lung of a Chameleon. It is this link of
+structure of the breathing organs between reptiles and birds that
+constitutes one of the chief interests of flying reptiles, for they
+prove to have possessed air cells prolonged from the lungs, which
+extended into the bones.
+
+
+
+
+CHAPTER III
+
+A REPTILE IS KNOWN BY ITS BONES
+
+
+Such are a few illustrations of ways in which reptiles resemble other
+animals, and differ from them, in the organs by means of which the
+classification of animals is made. But such an idea is incomplete
+without noticing that the bony framework of the body associated with
+such vital organs also shows in its chief parts that reptiles are easily
+recognised by their bones. I will therefore briefly state how reptiles
+are defined in some regions of the skeleton, for in tracing the history
+of reptile life the bones are the principal remains of animals preserved
+in the rocks; and the soft organs which have perished can only be
+inferred to have been present from the persistence of durable
+characteristic parts of the skeleton, which are associated with those
+soft organs in animals which exist at the present day, and are unknown
+in other animals in which the skeleton is different.
+
+
+THE HANG OF THE LOWER JAW
+
+The manner in which the lower jaw is connected with the skull yields one
+of the most easily recognised differences between the great groups of
+vertebrate animals.
+
+_In Mammals._--In every mammal--such as the Dog or Sheep--the lower jaw,
+which is formed of one bone on each side, joins directly on to the head
+of the animal, and moves upon a bone of the skull which is named the
+temporal bone. This character is sufficient to prove, by the law of
+association of soft and hard parts of the body, that such an animal had
+warm blood and suckled its young.
+
+  [Illustration: FIG. 2   _PTERODACTYLUS KOCHI_   SKULL OF BEAR
+
+  Comparison to show the articulation with the lower jaw in a mammal
+  and _Pterodactylus Kochi_. The quadrate bone is lettered Q in this
+  Pterodactyle, and comes between the skull and the lower jaw like the
+  quadrate bone in a bird and in lizards.]
+
+_In Birds._--In birds a great difference is found in this region of the
+head. The temporal bone, which it will be more convenient to name the
+squamosal bone, from its squamous or scale-like form, is still a part of
+the brain case, and assists in covering the brain itself, exactly as
+among mammals. But the lower jaw is now made up of five or six bones.
+And between the hindermost and the squamosal there is an intervening bar
+of bone, unknown among mammalia, which moves upon the skull by a joint,
+just as the lower jaw moves upon it. This movable bone unites with parts
+of the palate and the face, and is known as the quadrate bone. Its
+presence proves that the animal possessing it laid eggs, and if the
+face bones join its outer border just above the lower jaw, it proves
+that the animal possessed hot blood.
+
+_In Reptiles._--All reptiles are also regarded as possessing the
+quadrate bone. But the squamosal bone with which it always unites is in
+less close union with the brain case, and never covers the brain itself.
+Serpents show an extreme divergence in this condition from birds, for
+the squamosal bone appears to be a loose external plate of bone which
+rests upon the compact brain case and gives attachment to the quadrate
+bone which is as free as in a bird. Among Lizards the quadrate bone is
+usually almost as free. In the other division of existing Reptilia,
+including Crocodiles, the New Zealand lizard-like reptile Hatteria,
+called Tuatera, and Turtles, the squamosal and quadrate bones are firmly
+united with the bones of the brain case, face, and palate, so that the
+quadrate bone has no movement; and the same condition appears in
+amphibians, such as Toads and Frogs. With these conditions of the
+quadrate bone are associated cold blood, terrestrial life, and young
+developed from eggs.
+
+_In Fishes._--Bony fishes, and all others in which separate bones build
+up the skull, differ from Reptiles and Birds much as those animals
+differ from Mammals. The union of the lower jaw with the skull becomes
+complicated by the presence of additional bones. The quadrate bone still
+forms a pulley articulation upon which the lower jaw works, but between
+it and the squamosal bone is the characteristic bone of the fish known
+as the hyomandibular, commonly connected with opercular bones and
+metapterygoid which intervene, and help to unite the quadrate with the
+brain case. In the Cartilaginous fishes there is only one bone
+connecting the jaws with the skull on each side. This appears to prove
+that just as the structure of the arch of bones suspending the jaw may
+be complicated by the mysterious process called segmentation, which
+separates a bone into portions, so simplification and variation may
+result because the primitive divisions of the material cease to be made
+which exists before bones are formed.
+
+The principal regions of the skull and skeleton all vary in the chief
+groups of animals with backbones; so that the Reptile may be recognised
+among fossils, even in extinct groups of animals and occasionally
+restored from a fragment, to the aspect which characterised it while it
+lived.
+
+
+
+
+CHAPTER IV
+
+ANIMALS WHICH FLY
+
+
+The nature of a reptile is now sufficiently intelligible for something
+to be said concerning flight, and structures by means of which some
+animals lift themselves in the air. It is not without interest to
+remember that, from the earliest periods in human records,
+representations have been made of animals which were furnished with
+wings, yet walked upon four feet, and in their typical aspect have the
+head shaped like that of a bird. They are commonly named Dragons.
+
+
+FLYING DRAGONS
+
+  [Illustration: FIG. 3  From _The Battle between Bel and the Dragon_]
+
+The effigy of the dragon survives to the present day in the figure over
+which St. George triumphs, on the reverse of the British sovereign. In
+the luxuriant imaginations of ancient Eastern peoples, dating back to
+prehistoric ages, perhaps 5000 B.C., the dragons present an astonishing
+constancy of form. In after-times they underwent a curious evolution, as
+the conception of Babylon and Egypt is traced through Assyria to Greece.
+The Wings, which had been associated at first with the fore limb of the
+typical dragon, become characteristic of the Lion, and of the poet's
+winged Horse, and finally of the Human figure itself, carved on the
+great columns of the Greek temples of Ephesus. These flying animals are
+historically descendants of the same common stock with the dragons of
+China and Japan, which still preserve the aspect of reptiles. Their
+interest is chiefly in evidence of a latent spirit of evolution in days
+too remote for its meaning to be now understood, which has carried the
+winged forms higher and ever higher in grade of organisation, till their
+wings ceased to be associated with feelings of terror. The Hebrew
+cherubim are regarded by H. E. Ryle, Bishop of Exeter, as probably
+Dragons, and the figure of the conventional angel is the human form of
+the Dragon.
+
+  [Illustration: FIG. 4.  FIGURE FROM THE TEMPLE OF EPHESUS]
+
+
+ORGANS OF FLIGHT
+
+Turning from this reference to the realm of mythology to existing
+nature, the power of flight is popularly associated with all the chief
+types of vertebrate animals--fishes, frogs, lizards, birds, and mammals.
+Many of the animals ill deserve the name of flyers, and most are
+exceptions to different conditions of existence which control their
+kindred, but it is convenient to examine for a little the nature of the
+structures by which this movement in the air, which is not always
+flight, is made possible. Certain fishes, like the lung-fish Ceratodus,
+of Queensland, and the mud-fish Lepidosiren, are capable of leaving the
+water and living on land, and for a time breathe air. But neither these
+fishes nor Periophthalmus, which runs with rapid movement of its fins
+and carries the body more or less out of water, or the climbing perch,
+Anabas, carried out of water over the country by Indian jugglers, ever
+put on the slightest approach to wings.
+
+
+FLYING FISHES
+
+  [Illustration: FIG. 5.  THE FLYING FISH EXOCOETUS
+
+  With the fins extended moving through the air]
+
+The flight of fishes is a kind of parachute support not unlike that by
+which a folded paper is made to travel in the air. It is chiefly seen in
+the numerous species of a genus Exocoetus, allied to the gar-pike
+(Belone), which is common in tropical seas, and usually from a foot to
+eighteen inches long. They emerge from the water, and for a time support
+themselves in the air by means of the greatly developed breast fins,
+which sometimes extend backward to the tail fin. Although these fins
+appear to correspond to the fore limbs of other animals, they may not be
+moved at the will of the fish like the wing of a bird. When the flying
+fishes are seen in shoals in the vicinity of ships, those fins remain
+extended, so that the fish is said sometimes to travel 200 yards at a
+speed of fifteen miles an hour, rising twenty feet or more above the
+surface of the sea, travelling in a straight line, though sometimes
+influenced by the wind. Here the organ, which is at once a fin and a
+wing, consists of a number of thin long rods, or rays, which are
+connected by membrane, and vary in length to form an outline not unlike
+the wing of a bird which tapers to a point. The interest of these
+animals is chiefly in the fact that flight is separated from the
+condition of having lungs with which it is associated in birds, for
+although the flying fish has an air bladder, there is no duct to connect
+it with the throat.
+
+
+FLYING FROGS
+
+  [Illustration: FIG. 6.  THE FLYING FROG (RHACOPHORUS)
+
+  The membranes of the foot and hand extend between the metatarsal and
+  metacarpal bones, as well as the bones of the digits.]
+
+Among amphibians the organs of flight are also of a parachute kind, but
+of a different nature. They are seen in certain frogs which frequent
+trees, and are limited to membranes which extend between the diverging
+digits of the hand and foot, forming webs as fully developed as in the
+foot of a swimming bird. As these frogs leap, the membranes are expanded
+and help to support the weight of the body, so that the animal descends
+more easily as it moves from branch to branch. There is no evidence that
+the bones of the digits ever became elongated like the fin rays of the
+flying fish or the wing bones of a Bat; but the web suggests the basis
+of such a wing, and the possibilities under which wings may first
+originate, by elongation of the bones of a webbed hand like that of a
+Flying Frog.
+
+
+FLYING LIZARDS
+
+  [Illustration: FIG. 7.  THE FLYING DRAGON, DRACO
+
+  Forming a parachute by means of the extended ribs]
+
+The Reptilia in their several orders are remarkable for absence of any
+modification of the arms which might suggest a capacity for acquiring
+wings, as being latent in their organisation. Crocodiles, Tortoises, and
+Serpents are alike of the earth, and not of the air. But among Lizards
+there are small groups of animals in which a limited capacity for
+movement through the air is developed. It is best known in the family of
+small lizards named Dragons, represented typically by the species _Draco
+volans_ found in the Oriental region of the East Indies and Malay
+Archipelago.
+
+The organ of flight is produced in an unexpected way, by means of the
+ribs instead of the limbs. The ribs extend outward as far as the arms
+can stretch, and the first five or six are prolonged beyond the body so
+as to spread a fold of skin on each side between the arm and the leg.
+The membrane admits of some movement with the ribs. This arrangement
+forms a parachute, which enables the animal to move rapidly among
+branches of trees, extending the structure at will, so that it is used
+with rapidity too quick to be followed by the eye, as it leaps through
+considerable distances.
+
+A less singular aid to movement in the air is found in some of the
+lizards termed Geckos. The so-called Flying Gecko (_Platydactylus
+homalocephalus_) has a fringe unconnected with ribs, which extends
+laterally on the sides of the body and tail, as well as at the back and
+front of the fore and hind limbs, and between the digits, where the web
+is sometimes almost as well developed as among Tree Frogs. This is
+essentially a lateral horizontal frill, extending round the body. Its
+chief interest is in the circumstance that it includes a membrane which
+extends between the wrist bones and the shoulder on the front of the
+arm. That is the only part of the fringe which represents the wing
+membrane of a bird. The fossil flying reptiles have not only that
+membrane, but the lateral membranes at the sides of the body and behind
+the arms.
+
+Other lizards have the skin developed in the direction of the
+circumference of the body. In the Australian Chlamydosaurus it forms an
+immense frill round the neck like a medi�val collar. But though such an
+adornment might break a fall, it could not be regarded as an organ of
+flight.
+
+
+FLYING BIRDS
+
+  [Illustration: FIG. 8.  POSITION OF BIRDS IN FLIGHT]
+
+The wings of birds, when they are developed so as to minister to flight,
+are all made upon one plan; but as examples of the variation which the
+organs contributing to make the fore limb manifest, I may instance the
+short swimming limb of the Penguin, the practically useless rudiment of
+a wing found in the Ostrich or Kiwi, and the fully developed wing of the
+Pigeon. The wings of birds obtain an extensive surface to support the
+animal by muscular movements of three modifications of structure. First,
+the bones of the fore limb are so shaped that they cannot, in existing
+birds, be applied to the ground for support and be used like the limbs
+of quadrupeds, and are therefore folded up at the sides of the body,
+and carried in an unused or useless state so long as the animal hops on
+the ground or walks, balancing its weight on the hind legs. Secondly,
+there are two small folds of skin, less conspicuous than those on the
+arms of Geckos; one is between the wrist bones and the shoulder, and the
+smaller hinder membrane is between the upper arm and the body. These
+membranous expansions are insignificant, and would in themselves be
+inadequate to support the body or materially assist its movements.
+Thirdly, the bird develops appendages to the skin which are familiarly
+known as feathers, and the large feathers which make the wing are
+attached to the skin covering the lower arm bone named the ulna, and the
+other bones which represent the wrist and hand. The area and form of the
+bird's wing are due to individual appendages to the skin, which are
+unknown in any other group of animals. Between the extended wing of the
+Albatross, measuring eleven feet in spread, and the condition in the
+Kiwi of New Zealand, in which the wing is vanishing, there is every
+possible variation in size and form. As a rule, the larger the animal
+the smaller is the wing area. The problem of the origin of the bird's
+wing is not to be explained by study of existing animals; for the rowing
+organ of the Penguin, which in itself would never suggest flight,
+becomes an organ of flight in other birds by the growth upon it of
+suitable feathers. Anyone who has seen the birds named Divers feeding
+under water, swimming rapidly with their wings, might never suspect that
+they were also organs of aerial flight. The Ostrich is even more
+interesting, for it has not developed flight, and still retains at the
+extremities of two of the digits the slender claws of a limb which was
+originally no wing at all, but the support of a four-footed animal (Fig.
+46, p. 130).
+
+
+FLYING MAMMALS
+
+Flight is also developed among mammals. The Insectivora include several
+interesting examples of animals which are capable of a certain motion
+through the air. In the tropical forests of the Malay Archipelago are
+animals known as Flying Squirrels, Flying Opossums, Flying Lemurs,
+Flying Foxes, in which the skin extends outward laterally from the sides
+of the body so as to connect the fore limbs with the hind limbs, and is
+also prolonged backward from the hind limbs to the tail. The four digits
+are never elongated; the bones of the fore limb are neither longer nor
+larger than those of the hind limb, and the foot terminates in five
+little claws as in other four-footed animals. This condition is adapted
+for the arboreal life which those animals live, leaping from branch to
+branch, feeding on fruits and leaves, and in some cases upon insects.
+These mammals may be compared with the Flying Geckos among reptiles in
+their parachute-like support by extension of the skin, which gives them
+one of the conditions of support which contribute to constitute flight.
+
+  [Illustration: FIG. 9.  FLYING SQUIRREL (PTEROMYS)]
+
+_Bats._--One entire order of mammals--the Bats--not only possess true
+wings, but are capable of flight which is sustained, and in some cases
+powerful. The wings are clothed with short hair like the rest of the
+body, and thus the instrument of flight is unlike that of a bird. The
+flight of a Bat differs from that of all other animals in being
+dependent upon a modification of the bones of the fore limb, which,
+without interfering with the animal's movements as a quadruped, secures
+an extension of the wing which is not inferior in area to that which the
+bird obtains by elongation of the bones of the arm and fore-arm and its
+feathers. The distinctive peculiarity of the Bat's wing is in the
+circumstance that four of the digits of the hand have their bones
+prolonged to a length which is often equal to the combined length of the
+arm and fore-arm. The bones of the digits diverge like the ribs of an
+umbrella, and between them is the wing membrane, which extends from the
+sides of the body outward, unites the fore limb with the hind limb, and
+is prolonged down the tail as in the Flying Foxes. Bats have a small
+membrane in front of the bones of the arm and fore-arm stretching
+between the shoulder and the wrist, which corresponds with the wing
+membrane of a bird; but the remainder of the membranes in Bats' wings
+are absent in birds, because their function is performed by feathers
+which give the wing its area. The elongated digits of the Bat's wing are
+folded together and carried at the sides of the body as though they were
+a few quill pens attached to its wrist, where the one digit, which is
+applied to the ground in walking, terminates in a claw.
+
+  [Illustration: FIG. 10  NEW ZEALAND BAT FLYING. BARBASTELLE WALKING]
+
+The organs which support animals in the air are thus seen to be more or
+less dissimilar in each of the great groups of animals. They fall into
+three chief types: first, the parachute; secondly, the wing due to the
+feathers appended to the skin; and thirdly, the wing formed of membrane,
+supported by enormous elongation of the small bones of the back of the
+hand and fingers. The two types of true wings are limited to birds and
+bats; and no living reptile approximates to developing such an organ of
+flight as a wing. Judged, therefore, by the method of comparing the
+anatomical structures of one animal with another, which is termed
+"comparative anatomy," the existence of flying reptiles might be
+pronounced impossible. But in the light which the revelations of geology
+afford, our convictions become tempered with modesty; and we learn that
+with Nature nothing is impossible in development of animal structure.
+
+
+
+
+CHAPTER V
+
+DISCOVERY OF THE PTERODACTYLE
+
+
+Late in the eighteenth century, in 1784, a small fossil animal with
+wings began to be known through the writings of Collini, as found in the
+white lithographic limestone of Solenhofen in Bavaria, and was regarded
+by him as a former inhabitant of the sea. The foremost naturalist of the
+time, the citizen Cuvier--for it was in the days of the French
+Republic--in 1801, in lucid language, interpreted the animal as a genus
+of Saurians. That word, so familiar at the present day, was used in the
+first half of the century to include Lizards and Crocodiles; and
+described animals akin to reptiles which were manifestly related neither
+to Serpents nor Turtles. But the term saurian is no longer in favour,
+and has faded from science, and is interesting only in ancient history
+of progress. The lizards soon became classed in close alliance with
+snakes. And the crocodiles, with the Hatteria, were united with
+chelonians. Most modern naturalists who use the term saurian still make
+it an equivalent of lizard, or an animal of the lizard kind.
+
+
+CUVIER
+
+  [Illustration: FIG. 11.  _PTERODACTYLUS LONGIROSTRIS_ (Cuvier)
+
+  The remains are preserved with the neck arched over the back, and the
+  jaws opened upward]
+
+Cuvier defined this fossil from Solenhofen as distinguished by the
+extreme elongation of the fourth digit of the hand, and from that
+character invented for the animal the name Pterodactyle. He tells us
+that its flight was not due to prolongation of the ribs, as among the
+living lizards named Dragons; or to a wing formed without the digits
+being distinguishable from each other, as among Birds; nor with only one
+digit free from the wing, as among Bats; but by having the wing
+supported mainly by a single greatly elongated digit, while all the
+others are short and terminate in claws. Cuvier described the amazing
+animal in detail, part by part; and such has been the influence of his
+clear words and fame as a great anatomist that nearly every writer in
+after-years, in French and in English, repeated Cuvier's conclusion,
+maintained to the end, that the animal is a saurian.
+
+  [Illustration: FIG. 12.  THE SKELETON OF _PTERODACTYLUS LONGIROSTRIS_
+
+  Reconstructed from the scattered bones in Fig. 14, showing the limbs
+  on the left side]
+
+Long before fashion determined, as an article of educated belief, that
+fossil animals exist chiefly to bridge over the gaps between those which
+still survive, the scientific men of Germany were inclined to see in the
+Pterodactyle such an intermediate type of life. At first S�mmerring and
+Wagler would have placed the Pterodactyle between mammals and birds.
+
+
+GOLDFUSS
+
+  [Illustration: FIG. 13.  THE _PTERODACTYLUS LONGIROSTRIS_ RESTORED
+  FROM THE REMAINS IN FIG. 11
+
+  Showing positions of the wing membranes with the animal at rest]
+
+But the accomplished naturalist Goldfuss, who described another fine
+skeleton of a Pterodactyle in 1831, saw in this flying animal an
+indication of the course taken by Nature in changing the reptilian
+organisation to that of birds and mammals. It is the first flash of
+light on a dark problem, and its brilliance of inference has never been
+equalled. Its effects were seen when Prince Charles Bonaparte, the
+eminent ornithologist, in Italy, suggested for the group the name
+Ornithosauria; when the profound anatomist de Blainville, in France,
+placed the short-tailed animal in a class between Reptiles and Birds
+named Pterodactylia; and Andreas Wagner, of Munich, who had more
+Pterodactyles to judge from than his predecessors, saw in the fossil
+animal a saurian in transition to a bird.
+
+
+VON MEYER
+
+But the German interpretation is not uniform, and Hermann von Meyer, the
+banker-naturalist of Frankfurt a./M., who made himself conversant with
+all that his predecessors knew, and enlarged knowledge of the
+Pterodactyles on the most critical facts of structure, continued to
+regard them as true reptiles, but flying reptiles. Such is the influence
+of von Meyer that all parts of the world have shown a disposition to
+reflect his opinions, especially as they practically coincide with the
+earlier teaching of Cuvier. Owen and Huxley in England, Cope and Marsh
+in America, Gaudry in France, and Zittel in Germany have all placed the
+Pterodactyles as flying reptiles. Their judgment is emphatic. But there
+is weight of competent opinion to endorse the evolutionary teaching of
+Goldfuss that they rise above reptiles. To form an independent opinion
+the modern student must examine the animals, weigh their characters bone
+by bone, familiarise himself, if possible, with some of the rocks in
+which they are found; to comprehend the conditions under which the
+fossils are preserved, which have added not a little to the interest in
+Pterodactyles, and to the difficulty of interpretation.
+
+
+GEOLOGICAL HISTORY OF PTERODACTYLES IN GERMANY
+
+We may briefly recapitulate the geological history. Those remains of
+Ornithosaurs which have been mentioned, with a multitude of others which
+are the glory of the museums of Munich, Stuttgart, T�bingen,
+Heidelberg, Bonn, Haarlem, and London, have all been found in working
+the lithographic stone of Bavaria. The whitish yellow limestone forms
+low, flat-topped hills, now isolated from each other by natural
+denudation, which has removed the intervening rock. The stone is found
+at some distance north of the Danube, in a line due north of Augsburg,
+in the country about Pappenheim, and especially at the villages of
+Solenhofen, Eichst�dt, Kelheim, and Nusplingen. These beds belong to the
+rocks which are named White Jura limestone in Germany, which is of about
+the same geological age as the Kimeridge clay in England. Much of it
+divides into very thin layers, and in these planes of separation the
+fossils are found. They include the _Ammonites lithographicus_ and a
+multitude of marine shells, king crabs and other Crustacea, sea-urchins,
+and other fossils, showing that the deposit was formed in the sea. The
+preservation of jelly-fish, which so soon disappear when left dry on the
+beach, shows that the ancient calcareous mud had unusual power of
+preserving fossils. Into this sea, with its fishes great and small, came
+land plants from off the land, dragonflies and other insects, tortoises
+and lizards, Pterodactyles with their flying organs, and birds still
+clothed with feathers. Sometimes the wing membranes of the flying
+reptiles are found fully stretched by the wing finger, as in examples to
+be seen at Munich and in the Yale Museum in Newhaven, in America. At
+Haarlem there is an example in which the wing membrane appears to be
+folded much as in the wing of a Bat, when the animal hangs suspended,
+with the flying membrane bent into a few wide undulations.
+
+The Solenhofen Slate belongs to about the middle period of the history
+of flying reptiles, for they range through the Secondary epochs of
+geological time. Remains are recorded in Germany from the Keuper beds at
+the top of the Trias, which is the bottom division of the Secondary
+strata; and I believe I have seen fragments of their bones from the
+somewhat older Muschelkalk of Germany.
+
+
+THEIR HISTORY IN ENGLAND
+
+In England the remains are found for the first time in the Lower Lias of
+Lyme Regis, in Dorset, and the Upper Lias of Whitby, in Yorkshire. In
+W�rtemberg they occur on the same horizons. They reappear in England, in
+every subsequent age, when the conditions of the strata and their
+fossils give evidence of near proximity to land. In the Stonesfield
+Slate of Stonesfield, in Oxfordshire, the bones are found isolated, but
+indicate animals of some size, though not so large as the rare bones of
+reputed true birds which appear to have left their remains in the same
+deposit.
+
+At least two Pterodactyles are found in the Oxford clay, known from more
+or less fragmentary remains or isolated bones; just as they occur in the
+Kimeridge Clay, Purbeck Limestone, Wealden sandstones, and especially in
+newer Secondary rocks, named Gault, Upper Greensand, and Chalk, in the
+south-east of England.
+
+Owing to exceptional facilities for collecting, in consequence of the
+Cambridge Greensand being excavated for the valuable mineral phosphate
+of lime it contains, more than a thousand bones are preserved, more or
+less broken and battered, in the Woodwardian Museum of the University
+of Cambridge alone. To give some idea of their abundance, it may be
+stated that they were mostly gathered during two or three years, as a
+matter of business, by an intelligent foreman of washers of the nodules
+of phosphate of lime, which, in commerce, are named coprolites. He soon
+learned to distinguish Pterodactyle bones from other fossils by their
+texture, and learned the anatomical names of bones from specimens in the
+University Museum. This workman, Mr. Pond, employed by Mr. William
+Farren, brought together not only the best of the remains at Cambridge,
+but most of those in the museums at York and in London, and the
+thousands of less perfect specimens in public and private collections
+which passed through the present writer's hands in endeavours to secure
+for the University useful illustrations of the animal's structure. These
+fragments, among which there are few entire bones, are valuable, for
+they have afforded opportunities of examining the articular ends of
+bones in every aspect, which is not possible when similar organic
+remains are embedded in rock in their natural connexions.
+
+In England Flying Reptiles disappear with the Chalk. In that period they
+were widely distributed, being found in Bohemia, in Brazil, and Kansas
+in the United States, as well as in Kent and other parts of England.
+They attained their largest dimensions in this period of geological
+time. One imperfect fragment of a bone from the Laramie rocks of Canada
+was described, I believe, by Cope, though not identified by him as
+Ornithosaurian, and is probably newer than other remains.
+
+
+ASPECT OF PTERODACTYLES
+
+If this series of animals could all be brought together they would vary
+greatly in aspect and stature, as well as in structure. Some have the
+head enormously long, in others it is large and deep, characters which
+are shared by extinct reptiles which do not fly, and to which some birds
+may approximate; while in a few the head is small and compact, no more
+conspicuous, relatively, than the head of a Sparrow. The neck may be
+slender like that of a Heron, or strong like that of an Eagle; the back
+is always short, and the tail may be inconspicuous, or as long as the
+back and neck together. These flying reptiles frequently have the
+proportions of the limbs similar to those of a Bat, with fore legs
+strong and hind legs relatively small; while in some the limbs are as
+long, proportionately, and graceful as those of a Deer. With these
+differences in proportions of the body are associated great differences
+in the relative length of the wing and spread of the wing membranes.
+
+
+DIMENSIONS OF THE ANIMALS
+
+The dimensions of the animals have probably varied in all periods of
+geological time. The smallest, in the Lithographic Slate, are smaller
+than Sparrows, while associated with them are others in which the
+drumstick bone of the leg is eight inches long. In the Cambridge
+Greensand and Chalk imperfect specimens occur, showing that the upper
+arm bones are larger than those of an Ox. The shaft is one and a half
+inches in diameter and the ends three inches wide. Such remains may
+indicate Pterodactyles not inferior in size to the extinct Moas of New
+Zealand, but with immensely larger heads, animals far larger than birds
+of flight.
+
+The late Sir Richard Owen, on first seeing these fragmentary remains,
+said "the flying reptile with outstretched pinions must have appeared
+like the soaring Roc of Arabian romance, but with the features of
+leathern wings with crooked claws superinduced, and gaping mouth with
+threatening teeth." Eventually we shall obtain more exact ideas of their
+aspect, when the structures of the several regions of the body have been
+examined. The great dimensions of the stretch of wing, often computed at
+twenty feet in the larger examples, might lead to expectations of great
+weight of body, if it were not known that an albatross, with wings
+spreading eleven feet, only weighs about seventeen pounds.
+
+
+
+
+CHAPTER VI
+
+HOW ANIMALS ARE INTERPRETED BY THEIR BONES
+
+
+There is only one safe path which the naturalist may follow who would
+tell the story of the meaning and nature of an extinct type of animal
+life, and that is to compare it as fully as possible in its several
+bones, and as a whole, with other animals, especially with those which
+survive. It is easy to fix the place in nature of living animals and
+determine their mutual relations to each other, because all the
+organs--vital as well as locomotive--are available for comparison. On
+such evidence they are grouped together into the large divisions of
+Beasts, Birds, and Reptiles; as well as placed in smaller divisions
+termed Orders, which are based upon less important modifications of
+fundamental structures. All these characteristic organs have usually
+disappeared in the fossil. Hence a new method of study of the hard parts
+of the skeleton, which alone are preserved, is used in the endeavour to
+discover how the Flying Reptile or other extinct animal is to be
+classified, and how it acquired its characters or came into existence.
+
+
+VARIATIONS OF BONES AMONG MAMMALIA
+
+  [Illustration: FIG. 14.  THE FORE LIMB IN FOUR TYPES OF MAMMALS
+
+  Comparison of the fore limb in mammals, showing variation of form
+  of the bones with function]
+
+Resemblances and differences in the bones are easily over-estimated in
+importance as evidence of pedigree relationship. The Mammalia show, by
+means of such skeletons as are exhibited in any Natural History Museum,
+how small is the importance to be attached to even the existence of any
+group of bones in determining its grade of organisation. The whole Whale
+tribe suckle their young and conform to the distinctive characters in
+brain and lungs which mark them as being mammals. But if there is one
+part of the skeleton more than another which distinguishes the Mammalia,
+it is the girdle of bones at the hips which supports the hind limbs. It
+is characterised by the bone named the ilium being uniformly directed
+forward. Yet in the Whale tribe the hip-girdle and the hind limb which
+it usually supports are so faintly indicated as to be practically lost;
+while the fore limb becomes a paddle without distinction of digits, and
+is therefore devoid of hoofs or claws, which are usual terminations of
+the extremities in mammals. Yet this swimming paddle, with its
+ill-defined bones--sometimes astonishing in number, as well as in
+fewness of the finger bones--is represented by the burrowing fore limb
+of the Mole, which lives underground; by the elongated hoofed legs of
+the Giraffe, which lives on plains; and the extended arm and finger
+bones of the Bat, which are equally mammals with the Whale. From such
+comparison it is seen that no proportion, or form, or length, or use of
+the bones of the limbs, or even the presence of limbs, is necessarily
+characteristic of a mammal. No limitation can be placed upon the
+possible diversity of form or development of bones in unknown animals,
+when they are considered in the light of such experience of varied
+structural conditions in living members of a single class.
+
+What is true for the limbs and the bony arches which support them is
+true for the backbone also, for the ribs, and to some extent for the
+skull. The neck in the Whale is shortened almost beyond recognition. In
+the Giraffe the same seven vertebr� are elongated into a marvellous
+neck; so that in the technical definition of a mammal both are said to
+have seven neck vertebr�. Yet exceptions show a capacity for variation.
+One of the Sloths reduces the number to six, while another has nine
+vertebr� in the neck; proving that there is no necessary difference
+between a mammal and a reptile when judged by a character which is
+typically so distinctive of mammals as the number of the neck bones.
+
+The skull varies too, though to a less extent. The Great Ant-eater of
+South America is a mammal absolutely without teeth. The Porpoises have a
+simple unvarying row of conical teeth with single roots extending along
+the jaw. And the dental armature of the jaws, and relative dimensions of
+the skull bones, exhibit such diversity, in evidence of what may be
+parted with or acquired, that recognition of the many reptilian
+structures and bones in the skull of Ornithorhynchus, the Australian
+Duckbill, demonstrates that the difficulties in recognising an animal by
+its bones are real, unless we can discover the Animal Type to which the
+bones belong; and that there is very little in osteology which may not
+be lost without affecting an animal's grade of organisation.
+
+
+VARIATION IN SKIN COVERING OF MAMMALS
+
+Even the covering of the body varies in the same class, or even order of
+animals, so that the familiar growth on the skin is never its only
+possible covering. The Indian ant-eater, named Manis, which looks like a
+gigantic fir-cone, the Armadillo, which sheathes the body in rings of
+bone, bearing only a scanty development of hair, are examples of
+mammalian hair, as singular as the quills of a Porcupine, the horn of a
+Rhinoceros, or the growth of hair of varying length and stoutness on
+different parts of the body in various animals, or the imperfect
+development of hair in the marine Cetacea. Among living animals it is
+enough for practical purposes to say that a mammal is clothed with hair,
+but in a fossil state the hair must usually be lost beyond recognition
+from its fineness and shortness of growth.
+
+
+VARIATION IN SKIN COVERING OF BIRDS
+
+No Class of living animals is more homogeneous than Birds; and
+well-preserved remains prove that, at least as far back in time as the
+Upper Oolites, birds were clothed with feathers of essentially the same
+mode of growth and appearance as the feathers of living birds. There
+may, therefore, be no ground for assuming that the covering was ever
+different, though some regions of the skin are free from feathers. Yet
+the variations from fine under-down to the scale-like feathers on the
+wings of a Penguin, or the great feathers in the wings of birds of
+flight, or the double quill of the Ostrich group, are calculated to
+yield dissimilar impressions in a fossil state, even if the fine down
+would be preserved in any stratum.
+
+
+VARIATION IN THE BONES OF BIRDS
+
+Osteologically there is less variety in the skeleton of birds than in
+other great groups of animals. The existing representatives do not
+exhaust its capability for modification. The few specimens of birds
+hitherto found in the Secondary strata have rudely removed many
+differences in the bones which separated living birds from reptiles; so
+that if only the older fossil birds were known, and the Tertiary and
+living birds had not existed, a bird might have been defined as an
+animal having its jaw armed with teeth, instead of devoid of teeth; with
+vertebr� cupped at both ends, instead of with a saddle-shaped
+articulation which in front is concave from side from side, and convex
+from above downwards; in which the bones of the hand are separate, so
+that three digits terminating in claws can be applied to the ground,
+instead of the metacarpal bones being united in a solid mass with
+clawless digits; and in which the tail is elongated like the tail of a
+lizard. Yet the limits to variation are not to be formulated till Nature
+has exhausted all her resources in efforts to preserve organic types by
+adapting them to changed circumstances. Birds may be regarded
+theoretically as equally capable with mammals of parting with almost
+every distinctive structure in the skeleton by which it is best known.
+Even the living frigate bird blends the early joints of the backbone
+into a compact mass like a sacrum. The Penguin has a cup-and-ball
+articulation in the early dorsal vertebr�, with the ball in front. And
+the genus Cypselus has the upper arm bone almost as broad as long,
+unlike the bird type. Such examples prove that we are apt to accept the
+predominant structures in an animal type as though they were universal,
+and forget that inferences based, like those of early investigators, on
+limited materials may be re-examined with advantage.
+
+
+VARIATION IN THE BONES OF REPTILES
+
+The true Reptilia, notwithstanding some strong resemblances to Birds in
+technical characters of the skeleton, display among their surviving
+representatives an astonishing diversity in the bony framework of the
+body, exceeding that of the mammalia. This unlooked-for capacity for
+varying the plan of construction of the skeleton is in harmony with the
+diversity of structure in groups of extinct animals to which the name
+reptiles has also been given. The interval in form is so vast between
+Serpent and Tortoise, and so considerable in structure of the skeleton
+between these and the several groups of Lizards, Crocodiles, and
+Hatteria, that any other diversity could not be more surprising. And the
+inference is reasonable that just as mammals live in the air, in the
+sea, on the earth, and burrow under the earth, similar modes of
+existence might be expected for birds and reptiles, though no bird is
+yet known to have put on the aspect of a fish, and no reptiles have been
+discovered which roamed in herds like antelopes, or lived in the air
+like birds or bats, unless these fossil flying animals prove on
+examination to justify the name by which they are known.
+
+Comparative study of structure in this way demolishes the prejudice,
+born of experience of the life which now remains on earth, that the
+ideas of Reptile and of Flight are incongruous, and not to be combined
+in one animal. The comparative study of the parts of animals does not
+leave the student in a chaos of possibilities, but teaches us that
+organic structures, which mark the grades of life, have only a limited
+scope of change; while Nature flings away every part of the skeleton
+which is not vital, or changes its form with altering circumstances of
+existence, enforced by revolutions of the Earth's surface in geological
+time, in her efforts to save organisms from extinction and pass the
+grade of life onward to a later age.
+
+The bones are only of value to the naturalist as symbols, inherited or
+acquired, and vary in value as evidence of the nature and association of
+those vital organs which differentiate the great groups of the
+vertebrata.
+
+These distinctive structures, which separate Mammals, Birds, and
+Reptiles, are sometimes demonstrated by the impress of their existence
+left on the bones; or sometimes they may be inferred from the characters
+of the skeleton as a whole.
+
+
+
+
+CHAPTER VII
+
+INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS
+
+
+THE ORGANS WHICH FIX AN ANIMAL'S PLACE IN NATURE
+
+We shall endeavour to ascertain what marks of its grade of organisation
+the Pterodactyle has to show. The organs which are capable of modifying
+the bones are probably limited to the kidneys, the brain, and the organs
+of respiration. It may be sufficient to examine the latter two.
+
+
+PNEUMATIC FORAMINA IN PTERODACTYLES
+
+  [Illustration: FIG. 15.  HEAD OF THE HUMERUS OF THE PTERODACTYLE
+  ORNITHOCHEIRUS
+
+  Showing position of the pneumatic foramen on the ulnar side of the
+  bone as in a bird]
+
+Hermann von Meyer, the historian of the Ornithosaurs of the Lithographic
+Slate, as early as 1837 described some Pterodactyle bones from the Lias
+of Franconia, which showed that air was admitted into the interior of
+the bones by apertures near their extremities, which, from this
+circumstance, are known as pneumatic foramina. He drew the inference,
+naturally enough, that such a structure is absolute proof that the
+Pterodactyle was a flying animal. It was not quite the right form in
+which the conclusion should have been stated, because the Ostrich and
+other birds which do not fly have the principal bones pneumatic.
+Afterwards, in 1859, the larger bones which Professor Sedgwick, of
+Cambridge, transmitted to Sir Richard Owen established this condition as
+characteristic of the Flying Reptiles of the Cambridge Greensand. It was
+thus found as a distinctive structure of the bones both at the beginning
+and the close of the geological history of these animals. Von Meyer
+remarks that the supposition readily follows that in the respiratory
+process there was some similarity between Pterodactyles and Birds. This
+cautious statement may perhaps be due to the circumstance that in many
+animals air cavities are developed in the skull without being connected
+with organs of respiration. It is well known that the bulk of the
+Elephant's head is due to the brain cavity being protected with an
+envelope formed of large air cells. Small air cells are seen in the
+skulls of oxen, pigs, and many other mammals, as well as in the human
+forehead. The head of a bird like the Owl owes something of its imposing
+appearance to the way in which its mass is enlarged by the dense
+covering of air cells in the bones above the brain, like that seen in
+some Cretaceous Pterodactyles. Nor are the skulls of Crocodiles or
+Tortoises exceptions to the general rule that an animal's head bones may
+be pneumatic without implying a pneumatic prolongation of air from the
+lungs. The mere presence of air cells without specification of the
+region of the skeleton in which they occur is not remarkable. The holes
+by which air enters the bones are usually much larger in Pterodactyles
+than in Birds, but the entrance to the air cell prolonged into the bones
+is the same in form and position in both groups. So far as can be judged
+by this character, there is no difference between them. The importance
+of the comparison can only be appreciated by examining the bones side by
+side. In the upper arm bone of a bird, on what is known as the ulnar
+border, near to the shoulder joint, and on the side nearest to it, is
+the entrance to the air cell in the humerus. In the Pterodactyle the
+corresponding foramen has the same position, form, and size, and is not
+one large hole, but a reticulation of small perforations, one beyond
+another, exactly such as are seen in the entrance to the air cell in the
+bone of a bird, in which the pneumatic character is found. For it is not
+every bird of flight which has this pneumatic condition of the bones;
+and Dr. Crisp stated that quite a number of birds--the Swallow, Martin,
+Snipe, Canary, Wood-wren and Willow-wren, Whinchat, Glossy-starling,
+Spotted-fly-catcher, and Black-headed Bunting--have no air in their
+bones. And it is well known that in many birds, especially water birds,
+it is only the upper bones of the limbs which are pneumatic, while the
+smaller bones retain the marrow.
+
+
+LUNGS AND AIR CELLS
+
+  [Illustration: FIG. 16.  LUNGS OF THE BIRD APTERYX PARTLY OPENED ON
+  THE RIGHT-HAND SIDE
+
+  The circles are openings of the bronchial tubes on the surface of the
+  lung. The notches on the inner edges of the lungs are impressions of
+  the ribs (After R. Owen)]
+
+  [Illustration: FIG. 17.  THE BODY OF AN OSTRICH LAID OPEN TO SHOW THE
+  AIR CELLS WHICH EXTEND THROUGH ITS LENGTH (After Georges Roch�)]
+
+It may be well to remember that the lungs of a bird are differently
+conditioned from those of any other animal. Instead of hanging freely
+suspended in the cone-shaped chamber of the thorax formed by the ribs
+and sternum, they are firmly fixed on each side, so that the ribs deeply
+indent them and hold them in place. The lungs have the usual internal
+structure, being made up of branching cells. The chief peculiarity
+consists in the way in which the air passes not only into them, but
+through them. The air tube of the throat of a bird, unlike that of a
+man, has the organ of voice, not at the upper end in the form of a
+larynx, but at the lower end, forming what is termed a syrinx. There is
+no evidence of this in a fossil state, although in a few birds the rings
+of the trach�a become ossified, and are preserved. But below the syrinx
+the trach�a divides into two bronchi, tubes which carry the ringed
+character into the lungs for some distance, and these give off branches
+termed bronchial tubes, the finer subdivisions from which, in their
+clustered minute branching sacs, make up the substance of the lung.
+There is nothing exceptional in that. But towards the outer or middle
+part of the ventral or under surface of the lungs, four or five rounded
+openings are seen on each side. Each of these openings resembles the
+entrance of the air cell into a bone, since it displays several smaller
+openings which lead to it. Each opening from the lung leads to an air
+cell. Those cells may be regarded as the blowing out of the membrane
+which covers the lungs into a film which holds air like a mass of soap
+bubbles, until the whole cavity of the body of a bird from neck to tail
+is occupied by sacculated air cells, commonly ten in number, five on
+each side, though two frequently blend at the base of the neck in the
+region of the #V#-shaped bone named the clavicle or furculum, popularly
+known as the merry-thought. Most people have seen some at least of
+these semi-transparent bladder-like air cells beneath the skin in the
+abdominal region of a fowl. The cells have names from their positions,
+and on each side one is abdominal, two are thoracic, one clavicular, and
+one cervical, which last is at the base of the neck. The clavicular and
+abdominal air cells are perhaps the most interesting. The air cell
+termed clavicular sends a process outward towards the arm, along with
+the blood vessels which supply the arm. Thus this air cell, entering the
+region of the axilla or arm-pit, enters the upper arm bone usually on
+its under side, close to the articular head of the humerus, and in the
+same way the air may pass from bone to bone through every bone in the
+fore limb. The hind limbs similarly receive air from the abdominal air
+cell, which supplies the femur and other bones of the leg, the sacrum,
+and the tail. But the joints of the backbone in front of the sacrum
+receive their air from the cervical air sac. The air cells are not
+limited to the bones, but ramify through the body, and in some cases
+extend among the muscles. A bird may be said to breathe not only with
+its lungs, but with its whole body. And it is even affirmed that
+respiration has been carried on through a broken arm bone when the
+throat was closed, and the bird under water.
+
+Birds differ greatly in the extent to which the aircell system prolonged
+from the lungs is developed, some having the air absent from every bone,
+while others, like the Swift, are reputed to have air in every bone of
+the body.
+
+Comparison shows that in so far as the bones are the same in Bird and
+Ornithosaur, the evidence of the air cells entering them extends to
+resemblance, if not coincidence, in every detail. No living group of
+animals except birds has pneumatic limb bones, in relation to the lungs;
+so that it is reasonable to conclude that the identical structures in
+the bones were due to the same cause in both the living and extinct
+groups of animals. It is impossible to say that the lungs were identical
+in Birds and Pterodactyles, but so far as evidence goes, there is no
+ground for supposing them to have been different.
+
+
+THE LUNGS OF REPTILES
+
+  [Illustration: FIG. 18.  THE SIDE OF THE BODY OF A CHAMELEON
+
+  Ribs removed to show the sacculate branched form of the lung]
+
+There is nothing comparable to birds, either in the lungs of living
+reptiles or in their relation to the bones. The Chameleon is remarkable
+in that the lung is not a simple bladder prolonged through the whole
+length of the body cavity, as in a serpent, but it develops a number of
+large lateral branches visible when the body is laid open. Except near
+the trach�a, where the tissue has the usual density of a lizard lung,
+the air cell is scarcely more complicated than the air bladder of a
+fish, and does not enter into any bone of the skeleton. And although
+many fishes like the Loach have the swim bladder surrounded by bone
+connected with the head, it offers no analogy to the pneumatic condition
+of the bones in the Pterodactyle.
+
+
+THE FORM OF THE BRAIN CAVITY
+
+  [Illustration: FIG. 19.  THE FORM OF THE BRAIN]
+
+But the identity of the pneumatic foramina in Birds and Flying Reptiles
+is not a character which stands by itself as evidence of organisation,
+for a mould of the form of the brain case contributes evidence of
+another structural condition which throws some light on the nature of
+Ornithosaurs. Among many of the lower animals, such as turtles, the
+brain does not fill the chamber in the dry skull, in which the same
+bones are found as are moulded upon the brain in higher animals. For the
+brain case in such reptiles is commonly an envelope of cartilage, as
+among certain fishes; and except among serpents, the Ophidia, the bones
+do not completely close the reptilian brain case in front. The brain
+fills the brain case completely among birds. A mould from its interior
+is almost as definite in displaying the several parts of which it is
+formed as the actual brain would be. And the chief regions of the brain
+in a bird--cerebrum, optic lobes, cerebellum--show singularly little
+variation in proportion or position. The essential fact in a bird's
+brain, which separates it absolutely from all other animals, is that the
+pair of nerve masses known as the optic lobes are thrust out at the
+sides, so that the large cerebral hemispheres extend partly over them as
+they extend between them to abut against the cerebellum. This remarkable
+condition has no parallel among other vertebrate animals. In Fishes,
+Amphibians, Reptiles, and Mammals the linear succession of the several
+parts of the brain is never departed from; and any appearance of
+variation from it among mammals is more apparent than real, for the
+linear succession may be seen in the young calf till the cerebral
+hemispheres grow upward and lop backward, so as to hide the relatively
+small brain masses which correspond to the optic lobes of reptiles,
+extending over these corpora-quadrigemina, as they are named, so as to
+cover more or less of the mass of the cerebellum. From these conditions
+of the brain and skull, it would not be possible to mistake a mould
+from the brain case of a bird for that of a reptile, though in some
+conditions of preservation it is conceivable that the mould of the brain
+of a bird might be distinguished with difficulty from that of the brain
+in the lowest mammals. Taken by itself, the avian form of brain in an
+animal would be as good evidence that its grade of organisation was that
+of a bird as could be offered.
+
+
+THE BRAIN IN SOLENHOFEN PTERODACTYLES
+
+It happens that moulds of the brain of Pterodactyles, more or less
+complete, are met with of all geological ages--Liassic, Oolitic, and
+Cretaceous. The Solenhofen Slate is the only deposit in Europe in which
+Pterodactyle skulls can be said to be fairly numerous. They commonly
+have the bones so thin as to show the form of the upper surface of the
+mould of the brain, or the bones have scaled off the mould, or remain in
+the counterpart slab of stone, so as to lay bare the shape of the brain
+mass.
+
+In the Museum at Heidelberg a skull of this kind is seen in the
+long-tailed genus of Pterodactyles named Rhamphorhynchus. It shows the
+large rounded cerebral hemispheres, which extend in front of cerebral
+masses of smaller size a little below them in position, which perhaps
+are as like the brain of a monotreme mammal as a bird.
+
+The short-tailed Pterodactylus described by Cuvier has the cerebral
+hemispheres very similar to those of a bird, but the relations of the
+hinder parts of the brain to each other are less clear.
+
+The first specimen to show the back of the brain was found by Mr. John
+Francis Walker, M.A., in the Cambridge Greensand. I was able to remove
+the thick covering of cellular bone which originally extended above it,
+and thus expose evidence that in the mutual relations of the fore and
+hind parts of the brain bird and ornithosaur were practically identical.
+Another Cambridge Greensand skull showed that in the genus
+Ornithocheirus the optic lobes of the brain are developed laterally, as
+in birds. That skull was isolated and imperfect. But about the same time
+the late Rev. W. Fox, of Brixton, in the Isle of Wight, obtained from
+Wealden beds another skull, with jaws, teeth, and the principal bones of
+the skeleton, which showed that the Wealden Pterodactyle Ornithodesmus
+had a similar and bird-like brain. In 1888 Mr. E. T. Newton, F.R.S.,
+obtained a skull from the Upper Lias, uncrushed and free from
+distortion. This made known the natural mould of the brain, which shows
+the cerebral hemispheres, optic lobes, and cerebellum more distinctly
+than in the specimens previously known. In some respects it recalls the
+Heidelberg brain of Rhamphorhynchus in the apparently transverse
+subdivision of the optic lobes, but it is unmistakably bird-like, and
+quite unlike any reptile.
+
+
+IMPORTANCE OF THE BRAIN AND BREATHING ORGANS
+
+So far as the evidence goes, it appears that these fossil flying animals
+show no substantial differences from birds, either in the mould of the
+brain or the impress of the breathing organs upon the bones. These
+approximations to birds of the nervous and respiratory systems, which
+are beyond question two of the most important of the vital organs of an
+animal, and distinctive beyond all others of birds, place the
+naturalist in a singular dilemma. He must elect whether he will trust
+his interpretation to the soft organs, which among existing animals
+never vary their type in the great classes of vertebrate animals, and on
+which the animal is defined as something distinct from its envelope the
+skeleton and its appendages the limbs, or whether he will ignore them.
+The answer must choose substantially between belief that the existing
+order of Nature gives warrant for believing that these vital
+characteristics which have been discussed might equally coexist with the
+skeleton of a mammal or a reptile, as with that of a bird, for which
+there is no particle of evidence in existing life. Or, as an
+alternative, the fact must be accepted that birds only have such vital
+organs as are here found, and therefore the skeleton, that may be
+associated with them, cannot affect the reference of the type to the
+same division of the animal kingdom as birds. The decision need not be
+made without further consideration. But brain and breathing organs of
+the avian type are structures of a different order of stability in most
+animals from the bones, which vary to a remarkable extent in almost
+every ordinal group of animals.
+
+
+TEMPERATURE OF THE BLOOD
+
+The organs of circulation and digestion are necessarily unknown. There
+are reasons why the blood may have been hot, such as the evidences from
+the wings of exceptional activity; though the temperature depends more
+upon the amount of blood in the body than upon the apparatus by which it
+is distributed. We speak of a Crocodile as cold-blooded, yet it is an
+animal with a four-chambered heart not incomparable with that of a
+bird. On the other hand, the Tunny, a sort of giant Mackerel, is a fish
+with a three-chambered heart, only breathing the air dissolved in water,
+which has blood as warm as a mammal, its temperature being compared to
+that of a pig. Several fishes have blood as warm as that of Manis, the
+scaly ant-eater; and many birds have hotter blood than mammals. The term
+"hot-blooded," as distinct from "cold-blooded," applied to animals, is
+relative to the arbitrary human standard of experience, and expresses no
+more than the circumstance that mammals and birds are warmer animals
+than reptiles and fishes.
+
+The exceptional temperature of the Flying Fish has led to a vague
+impression that physical activity and its effect upon the amount of
+blood which vigour of movement circulates, are more important in raising
+an animal's temperature than possession of the circulatory organs
+commonly associated with hot blood, which drive the blood in distinct
+courses through the body and breathing organs. Yet the kind of heart
+which is always associated with vital structures such as Pterodactyles
+are inferred to have possessed from the brain mould and the pneumatic
+foramina in the bones, is the four-chambered heart of the bird and the
+mammal. Considering these organs alone--of which the fossil bones yield
+evidence--we might anticipate, by the law of known association of
+structures, that nothing distinctly reptilian existed in the other soft
+part of the vital organisation, because there is no evidence in favour
+of or against such a possibility.
+
+
+
+
+CHAPTER VIII
+
+THE PLAN OF THE SKELETON
+
+
+While these animals are incontestably nearer to birds than to any other
+animals in their plan of organisation, thus far no proof has been found
+that they are birds, or can be included in the same division of
+vertebrate life with feathered animals. It is one of the oldest and
+soundest teachings of Linn�us that a bird is known by its feathers; and
+the record is a blank as to any covering to the skin in Pterodactyles.
+There is the strongest probability against feathers having existed such
+as are known in the Arch�opteryx, because every Solenhofen Ornithosaur
+appears to have the body devoid of visible or preservable covering,
+while the two birds known from the Solenhofen Slate deposit are well
+clothed with feathers in perfect preservation. We turn from the skin to
+the skeleton.
+
+The plan on which the skeleton is constructed remains as evidence of the
+animal's place in nature, which is capable of affording demonstration on
+which absolute reliance would have been placed, if the brain and
+pneumatic foramina had remained undiscovered. With the entire skeleton
+before us, it is inconceivable that anatomical science should fail to
+discover the true nature of the animal to which it belonged, by the
+method of comparing one animal with another. There is no lack of this
+kind of evidence of Pterodactyles in the three or four scores of
+skeletons, and thousands of isolated or associated bones, preserved in
+the public museums of Europe and America.
+
+I may recall the circumstance that the discovery of skeletons of fossil
+animals has occasionally followed upon the interpretation of a single
+fragment, from which the animal has been well defined, and sometimes
+accurately drawn, before it was ever seen. So I propose, before drawing
+any conclusions from the skeletons in the entirety of their
+construction, to examine them bone by bone, and region by region, for
+evidence that will manifest the nature of this brood of Dragons. Their
+living kindred, and perhaps their extinct allies, assembled as a jury,
+may be able to determine whether resemblances exist between them, and
+whether such similarity between the bones as exists is a common
+inheritance, or is a common acquisition due to similar ways of life, and
+no evidence of the grade of the organism among vertebrate animals.
+
+The bones of these Ornithosaurs, when found isolated, first have to be
+separated from the organisms with which they are associated and mixed in
+the geological strata. This discrimination is accomplished in the first
+instance by means of the texture of the surface. The density and polish
+of the bones is even more marked than in the bones of birds, and is
+usually associated with a peculiar thinness of substance of the bone,
+which is comparable to the condition in a bird, though usually a little
+stouter, so that the bones resist crushing better. Pterodactyle bones
+in many instances are recognised by their straightness and comparatively
+uniform dimensions, due to the exceptional number of long bones which
+enter into the structure of the wing as compared with birds. When the
+bones are unerringly determined as Ornithosaurian, they are placed side
+by side with all the bones which are most like them, till, judged by the
+standard of the structures of living animals, the fossil is found to
+show a composite construction as though it were not one animal but many,
+while its individual bones often show equally composite characters, as
+though parts of the corresponding bone in several animals had been
+cunningly fitted together and moulded into shape.
+
+
+THE PLAN OF THE HEAD IN ORNITHOSAURS
+
+The head is always the most instructive part of an animal. It is less
+than an inch long in the small Solenhofen skeleton named _Pterodactylus
+brevirostris_, and is said to be three feet nine inches long in the
+toothless Pterodactyle Ornithostoma from the Chalk of Kansas. Most of
+these animals have a long, slender, conical form of head, tapering to
+the point like the beak of a Heron, forming a long triangle when seen
+from above or from the side. Sometimes the head is depressed in front,
+with the beak flattened or rounded as in a Duck or Goose, and
+occasionally in some Wealden and Greensand species the jaws are
+truncated in front in a massive snout quite unlike any bird. The back of
+the head is sometimes rounded as among birds, showing a smooth
+pear-shaped posterior convexity in the region of the brain. Sometimes
+the back of the head is square and vertical or oblique. Occasionally a
+great crest of cellular tissue is extended backward from above the
+brain case over the spines of the neck bones.
+
+There are always from two to four lateral openings in the skull. First,
+the nostril is nearest to the extremity of the beak. Secondly, the
+orbits of the eyes are placed far backward. These two openings are
+always present. The nostril may incline upward. The orbits of the eyes
+are usually lateral, though their upper borders sometimes closely
+approximate, as in the woodpecker-like types from the Solenhofen Slate
+named _Pterodactylus Kochi_, now separated as another genus. In most
+genera there is an opening in the side of the head, between the eye hole
+and the nostril, known as the antorbital vacuity; and another opening,
+which is variable in size and known as the temporal vacuity, is placed
+behind the eye. The former is common in the skulls of birds, the latter
+is absent from all birds and found in many reptiles.
+
+The palate is usually imperfectly seen, but English and American
+specimens have shown that it has much in common with the palate in
+birds, though it varies greatly in form of the bones in representatives
+from the Lias, Oolites, and Cretaceous rocks.
+
+From the scientific aspect the relative size of the head, its form, and
+the positions and dimensions of its apertures and processes, are of
+little importance in comparison with its plan of construction, as
+evidenced by the positions and relations to each other of the bones of
+which it is formed. There usually is some difficulty in stating the
+limits of the bones of the skull, because in Pterodactyles, as among
+birds, they usually blend together, so that in the adult animal the
+sutures between the bones are commonly obliterated.
+
+Bones have relations to each other and places in the head which can only
+change as the organs with which they are associated change their
+positions. No matter what the position of a nostril may be--at the
+extremity of a long snout, as in an ant-eater, or far back at the top of
+the head in a porpoise, or at the side of the head in a bird--it is
+always bordered by substantially the same bones, which vary in length
+and size with the changing place of the nostril and the form of the
+head. Every region of the head is defined by this method of
+construction; so that eye holes and nose holes, brain case and jaw
+bones, palate and teeth, beak, and back of the skull are all instructive
+to those who seek out the life-history of these animals. We may briefly
+examine the head of an Ornithosaurian.
+
+
+BONES ABOUT THE NOSTRIL
+
+No matter what its form may be, the head of an Ornithosaur always
+terminates in front in a single bone called the intermaxillary. It sends
+a bar of bone backward above the visible nostrils, between them; and a
+bar on each side forms the margin of the jaw in which teeth are
+implanted. The bone varies in depth, length, sharpness, bluntness,
+slenderness, and massiveness. As the bone becomes long the jaw is
+compressed from side to side, and the openings of the nostrils are
+removed backward to an increasing distance from the extremity of the
+beak.
+
+The outer and hinder border of the nostril is made by another bone named
+the maxillary bone, which is usually much shorter than the premaxillary.
+It contains the hindermost teeth, which rarely differ from those in
+front, except in sometimes being smaller.
+
+The nasal bones, which always make the upper and hinder border of the
+nostrils, meet each other above them, in the middle line of the beak.
+
+  [Illustration: FIG. 20
+
+  Showing that the extremity of the jaws in Rhamphorhynchus was
+  sheathed in horn as in the giant Kingfisher, since the jaws
+  similarly gape in front.
+
+  The hyoid bones are below the lower jaw in the Pterodactyle.]
+
+The nostrils are unusually large in the Lias genus named Dimorphodon,
+and small in species of the genus Rhamphorhynchus from Solenhofen. Such
+differences result from the relative dimensions and proportions of these
+three bones which margin the nasal vacuity, and by varying growth of
+their front margins or of their hinder margins govern the form of the
+snout.
+
+The jaws are most massive in the genera known from the Wealden beds to
+the Chalk. The palatal surface is commonly flat or convex, and often
+marked by an elevated median ridge which corresponds to a groove in the
+lower jaw, though the median ridge sometimes divides the palate into two
+parallel concave channels. The jaw is margined with teeth which are
+rarely fewer than ten or more than twenty on each side. They are sharp,
+compressed from side to side, curved inward, and never have a saw-like
+edge on the back and front margins. No teeth occur upon the bones of the
+palate.
+
+In most birds there is a large vacuity in the side of the head between
+the nostril and the orbit of the eye, partly separated from it by the
+bone which carries the duct for tears named the lachrymal bone. The same
+preorbital vacuity is present in all long-tailed Pterodactyles, though
+it is either less completely defined or absent in the group with short
+tails. It affords excellent distinctive characters for defining the
+genera. In the long-tailed genus Scaphognathus from Solenhofen this
+preorbital opening is much larger than the nostril, while in Dimorphodon
+these vacuities are of about equal size. Rhamphorhynchus is
+distinguished by the small size of the antorbital vacuity, which is
+placed lower than the nostril on the side of the face. The aperture is
+always imperfectly defined in Pterodactylus, and is a relatively small
+vacuity compared with the long nostril. In Ptenodracon the antorbital
+vacuity appears to have no existence separate from the nostril which
+adjoins the eye hole. And so far as is known at present there is no
+lateral opening in advance of the eye in the skull in any Ornithosaur
+from Cretaceous rocks, though the toothless Ornithostoma is the only
+genus with the skull complete. When a separate antorbital vacuity
+exists, it is bordered by the maxillary bone in front, and by the malar
+bone behind. The prefrontal bone is at its upper angle. That bone is
+known in a separate state in reptiles and, I think, in monotreme
+mammals. Its identity is soon lost in the mammal, and its function in
+the skull is different from the corresponding bone in Pterodactyles.
+
+
+BONES ABOUT THE EYES
+
+  [Illustration: FIG. 21.  UPPER SURFACE OF SKULL OF THE HERON
+
+  Compared with the same aspect of the skull of Rhamphorhynchus]
+
+The third opening in the side of the head, counting from before
+backward, is the orbit of the eye. In this vacuity is often seen the
+sclerotic circle of overlapping bones formed in the external membrane of
+the eye, like those in nocturnal birds and some reptiles. The eye hole
+varies in form from an inverted pear-shape to an oblique or transverse
+oval, or a nearly circular outline. It is margined by the frontal bone
+above; the tear bone or lachrymal, and the malar or cheek bone in front;
+while the bones behind appear to be the quadrato-jugal and post-frontal
+bones, though the bones about the eye are somewhat differently arranged
+in different genera.
+
+The eyes were frequently, if not always, in contact with the anterior
+walls of the brain case, as in many birds, and are always far back in
+the side of the head. In Dimorphodon they are in front of the
+articulation of the lower jaw; in Rhamphorhynchus, above that
+articulation; while in Ornithostoma they are behind the articulation for
+the jaw. This change is governed by the position of the quadrate bone,
+which is vertical in the Lias genus, inclined obliquely forward in the
+fossils from the Oolites, and so much inclined in the Chalk fossil that
+the small orbit is thrown relatively further back.
+
+Thus far the chief difference in the Pterodactyle skull from that of a
+bird is in the way in which the malar arch is prolonged backward on each
+side. It is a slender bar of bone in birds, without contributing
+ascending processes to border vacuities in the side of the face, while
+in these fossil animals the lateral openings are partly separated by the
+ascending processes of these bones. This divergence from birds, in the
+malar bone entering the orbit of the eye is approximated to among
+reptiles and mammals, though the conditions, and perhaps the presence of
+a bone like the post-orbital bone, are paralleled only among Reptiles.
+The Pterodactyles differ among themselves enough for the head to make a
+near approach to Reptiles in Dimorphodon, and to Birds in
+Pterodactylus. In the Ground Hornbill and the Shoebill the lachrymal
+bones in front of the orbits of the eyes grow down to meet the malar
+bars without uniting with them. The post-frontal region also is
+prolonged downward almost as far as the malar bar, as though to show
+that a bird might have its orbital circle formed in the same way and by
+the same bones as in Pterodactylus. Cretaceous Ornithosaurs sometimes
+differ from birds apparently in admitting the quadrato-jugal bone into
+the orbit. It then becomes an expanded plate, instead of a slender bar
+as in all birds.
+
+
+THE TEMPORAL FOSSA
+
+A fourth vacuity is known as the temporal fossa. When the skull of such
+a mammal as a Rabbit, or Sheep, is seen from above, there is a vacuity
+behind the orbits for the eyes, which in life is occupied by the muscles
+which work the lower jaw. It is made by the malar bone extending from
+the back of the orbit and the process of bone, called the zygomatic
+process, extending forward from the articulation of the jaw, which
+arches out to meet the malar bone.
+
+In birds there is no conspicuous temporal fossa, because the malar bar
+is a slender rod of bone in a line with the lower end of the quadrate
+bone.
+
+Reptile skulls have sometimes one temporal vacuity on each side, as
+among tortoises, formed by a single lateral bar. These vacuities, which
+correspond to those of mammals in position, are seen from the top of the
+head, as lateral vacuities behind the orbits of the eyes, and are termed
+superior temporal vacuities. In addition to these there is often in
+other reptiles a lateral opening behind the eye, termed the inferior
+temporal vacuity, seen in Crocodiles, in Hatteria, and in Lizards; and
+in such skulls there are two temporal bars seen in side view,
+distinguished as superior and inferior. The superior arch always
+includes the squamosal bone, which is at the back of the single bar in
+mammals. The lower arch includes the malar bone, which is in front in
+the single arch of mammals. The circumstance that both these arches are
+connected with the quadrate bone makes the double temporal arch
+eminently reptilian.
+
+In Ornithosaurs the lateral temporal vacuity varies from a typically
+reptilian condition to one which, without becoming avian, approaches the
+bird type. In skulls from the Lias, Dimorphodon and Campylognathus,
+there is a close parallel to the living New Zealand reptile Hatteria, in
+the vertical position of the quadrate bone and in the large size of the
+vacuity behind and below the eye, which extends nearly the height of the
+skull. In the species of the genus Pterodactylus, the forward
+inclination of the quadrate bone recalls the Curlew, Snipe, and other
+birds. The back of the head is rounded, and the squamosal bone, which
+appears to enter into the wall of the brain case as in birds and
+mammals, is produced more outward than in birds, but less than in
+mammals, so as to contribute a little to the arch which is in the
+position of the post-frontal bone of reptiles. It is triangular, and
+stretches from the outer angle of the frontal bone at the back of the
+orbit to the squamosal behind, where it also meets the quadrate bone.
+Its third lower branch meets the quadratojugal, which rests upon the
+front of the quadrate bone, as in Iguanodon, and is unlike Dimorphodon
+in its connexions. In that genus the supra-temporal bone, or
+post-orbital bone, appears to rest upon the post-frontal and connect it
+with the quadrato-jugal. In Dimorphodon the malar bone is entirely
+removed from the quadrate, but in Pterodactylus it meets its articular
+end. Between the post-frontal bone above and the quadrato-jugal bone
+below is a small lunate opening, which represents the lateral temporal
+vacuity; and so far, this is a reptilian character. But if the thin
+post-frontal bone were absorbed, Pterodactylus would resemble birds.
+There is no evidence that the quadrate bone is free in any Ornithosaurs,
+as it is in all birds, while in Dimorphodon it unites by suture with the
+squamosal bone. In Ornithostoma the lateral temporal vacuity is little
+more than a slit between the quadrate bone below, the quadrato-jugal in
+front, and what may be the post-frontal bone behind (see Fig. 2, p. 12).
+
+
+BONES ABOUT THE BRAIN
+
+The bones containing the brain appear to be the same as form the brain
+case in birds. The form of the back of the skull varies in two ways.
+First it may be flat above and flat at the back, when the back of the
+head appears to be square. This condition is seen in all the long-tailed
+genera, such as Campylognathus from the Lias and Rhamphorhynchus, and is
+associated with a high position for the upper temporal bar. Secondly,
+the back of the head may be rounded convexly, both above and behind.
+That condition is seen in the short-tailed genera, such as
+Pterodactylus. But in the large Cretaceous types, such as Ornithocheirus
+and Ornithostoma, the superior longitudinal ridge which runs back in
+the middle line of the face becomes elevated and compressed from side to
+side at the back of the head as a narrow deep crest, prolonged backward
+over the neck vertebr� for some inches of length. All these three types
+are paralleled more or less in birds which have the back of the head
+square like the Heron, or rounded like the Woodpecker; or crested,
+though the crest of the Cormorant is not quite identical with
+Ornithocheirus, being a distinct bone at the back of the head in the
+bird which never blends with the skull. In so far as the crest is
+reptilian it suggests the remarkable crest of the Chameleon. In the
+structure of the back of the skull the bones are a modification of the
+reptilian type of Hatteria in the Lias genus Campylognathus, but the
+reptilian characters appear to be lost in the less perfectly preserved
+skulls of Cretaceous genera.
+
+The palate is well known in the chief groups of Ornithosaurs, such as
+Campylognathus, Scaphognathus, and Cycnorhamphus.
+
+Mr. E. T. Newton, F.R.S., has shown that in the English skull from the
+Lias of Whitby, the forms of the bones are similar to the palate in
+birds and unlike the conditions in reptiles. There is one feature,
+however, which may indicate a resemblance to Dicynodon and other fossil
+reptiles from South Africa. A slender bone extends from the base of the
+brain case, named the basi-sphenoid bone, outward and forward to the
+inner margin of the quadrate bone (Fig. 22). A bone is found thus placed
+in those South African Reptiles, which show many resemblances to the
+Monotreme and Marsupial Mammals. It is not an ordinary element of the
+skeleton and is unknown in living animals of any kind in that position.
+It has been thought possible that it may represent one of the bones
+which among mammals are diminutive and are included in the internal ear.
+The resemblance may have some interest hereafter, as helping to show
+that certain affinities of the Ornithosaurs may lie outside the groups
+of existing reptiles. Instead of being directed transversely outward, as
+in the palatal region of _Dicynodon lacerticeps_, they diverge outward
+and forward to the inner border of the articulation for the lower jaw
+which is upon the quadrate bone.
+
+  [Illustration: FIG. 22]
+
+
+BONES OF THE PALATE
+
+There is a pair of bones which extend forward from these inner articular
+borders of the quadrate bones, and converge in a long #V#-shape till
+they merge in the hard palate formed by the bones of the front of the
+beak, named intermaxillary and maxillary bones. The limits of the bones
+of the palate are not distinct, but there can be no doubt that the
+front of the #V# is the bone named vomer, that the palatine bones are at
+its sides, and that its hinder parts are the pterygoid bones as in
+birds. There is a long, wide, four-sided, open space in the middle of
+the palate, between the vomer and the basi-sphenoid bone, unlike
+anything in birds or other animals.
+
+Professor Marsh, in a figure of the palate in the great skull of the
+toothless Pterodactyle named Ornithostoma (Pteranodon), from the Chalk
+of Kansas, found a large oval vacuity in this region of the palate. In
+that genus the pterygoid bones meet each other between the quadrate
+bones as in Dicynodon (Fig. 73, p. 182). Hence the great palatal vacuity
+here seen in the Ornithosaur is paralleled by the small vacuity in the
+South African reptile, which is sometimes distinct and sometimes partly
+separated from the anterior part of the vacuity which forms the openings
+of the nostrils on the palate.
+
+The Solenhofen skulls which give any evidence of the palate are exposed
+in side view only, and the bones, imperfectly seen through the lateral
+vacuities, are displaced by crushing. They include long strips like the
+vomerine bones in the Lias fossil, and they diverge in the same way as
+they extend back to the quadrate bones. The oblique division into vomer
+in front and pterygoid bone behind is shown by Goldfuss in his original
+figure of Scaphognathus. Thus there is some reason for believing that
+all Ornithosaurs have the palate formed upon the same general plan,
+which is on the whole peculiar to the group, especially in not having
+the palatal openings of the nares divided in the middle line. It would
+appear probable that the short-tailed animals have the pterygoid bones
+meeting in the middle line and triangular; and that they are slender
+rods entirely separate from each other in the long-tailed genera.
+
+
+THE TEETH
+
+The teeth are all of pointed, elongated shape, without distinction into
+the kinds seen in most mammals and named incisors, canines, and
+grinders. They are organs for grasping, like the teeth of the
+fish-eating Crocodile of India, and are not unlike the simple teeth of
+some Porpoises. They are often implanted in oblique oval sockets with
+raised borders, usually at some distance apart from each other, and have
+the crown pointed, flattened more on the outer side than on the inner
+side, usually directed forward and curved inward. As in many extinct
+animals allied to existing reptiles, the teeth are reproduced by germs,
+which originate on the inner side of the root and grow till they
+gradually absorb the substance of the old tooth, forming a new one in
+its place. Frequently in Solenhofen genera, like Scaphognathus and
+Pterodactylus, the successional tooth is seen in the jaw on the hinder
+border of the tooth in use. There is some variation in the character of
+bluntness or sharpness of the crowns in the different genera, and in
+their size.
+
+The name Dimorphodon, given to the animal from the Lias of Lyme Regis,
+expresses the fact that the teeth are of two kinds. In the front of the
+jaw three or four large long teeth are found in the intermaxillary bone
+on each side, as in some Plesiosaurs, while the teeth found further back
+in the maxillary bone are smaller, and directed more vertically
+downward. This difference is more marked in the lower jaw than in the
+upper jaw. In Rhamphorhynchus the teeth are all relatively long and
+large, and directed obliquely forward, but absent from the extremities
+of the beak, as in the German genus from the Lias named Dorygnathus, in
+which the bone of the lower jaw (which alone is known) terminates in a
+compressed spear. In Scaphognathus the teeth are few, more vertical, and
+do not extend backward so far as in Rhamphorhynchus, but are carried
+forward to the extremity of the blunt, deep jaw.
+
+In the short-tailed Pterodactyles the teeth are smaller, shorter, wider
+at the base of the crown, closer together, and do not extend so far
+backward in the jaw. In Ornithocheirus two teeth always project forward
+from the front of the jaw. Ornithostoma is toothless.
+
+
+SUPPOSED HORNY BEAK
+
+Sometimes a horny covering has been suggested for the beak, like that
+seen in birds or turtles, but no such structure has been preserved, even
+in the Solenhofen Slate, in which such a structure would seem as likely
+to be preserved as a wing membrane, though there is one doubtful
+exception. There are marks of fine blood vessels on some of the jaws,
+indicating a tough covering to the bone. In Rhamphorhynchus the jaws
+appear to gape towards their extremities as though the interspace had
+originally been occupied by organic substance like a horny beak.
+
+
+LOWER JAW
+
+The lower jaw varies in relative length with the vertical or horizontal
+position of the quadrate bone in the skull. In Dimorphodon the jaw is as
+long as the skull; but in the genera from the Oolitic rocks the
+mandible is somewhat shorter, and in Ornithostoma the discrepancy
+reaches its maximum. The hinder part of the jaw is never prolonged
+backward much beyond the articulation, differing in this respect from
+Crocodiles and Plesiosaurs.
+
+The depth of the jaw varies. It is slender in Pterodactylus, and is
+probably stronger relatively to the skull in Scaphognathus than in any
+other form. It fits between the teeth and bones of the alveolar border
+in the skull, in all the genera. In Dimorphodon its hinder border is
+partly covered by the descending edge of the malar process which these
+animals develop in common with some Dinosaurs, and some Anomodont
+reptiles, and many of the lower mammals. In this hinder region the lower
+jaw is sometimes perforated, in the same way as in Crocodiles. That
+condition is observed in Dimorphodon, but is not found in Pterodactylus.
+The lower jaw is always composite, being formed by several bones, as
+among reptiles and birds. The teeth are in the dentary bone or bones,
+and these bones are almost always blended as in most birds and Turtles,
+and not separate from each other as among Crocodiles, Lizards, and
+Serpents.
+
+An interesting contour for the lower border of the jaw is seen in
+Ornithostoma, as made known in figures of American examples by
+Professors Marsh and Williston. It deepens as it extends backwards for
+two-thirds its length, stops at an angle, and then the depth diminishes
+to the articulation with the skull. This angle of the lower jaw is a
+characteristic feature of the jaws of Mammals. It is seen in the
+monotreme Echidna, and is characteristic of some Theriodont Reptiles
+from South Africa, which in many ways resemble Mammals. The character
+is not seen in the jaws of specimens from the Oolitic rocks, but is
+developed in the toothed Ornithocheirus from the Cambridge Greensand,
+and is absent from the jaws of existing reptiles and birds.
+
+  [Illustration: FIG. 23  COMPARISON OF THE LOWER JAW IN ECHIDNA AND
+  ORNITHOSTOMA]
+
+
+SUMMARY OF CHARACTERS OF THE HEAD
+
+Taken as a whole, the head differs from other types of animals in a
+blending of characters which at the present day are found among Birds
+and Reptiles, with some structures which occur in extinct groups of
+animals with similar affinities, and perhaps a slight indication of
+features common to the lowest mammals. It is chiefly upon the head that
+the diverse views of earlier writers have been based. Cuvier was
+impressed with the reptilian aspect of the teeth; but in later times
+discoveries were made of Birds with teeth--Arch�opteryx, Ichthyornis,
+Hesperornis. The teeth are quite reptilian, being not unlike miniature
+teeth of Mosasaurus. If those birds had been found prior to the
+discovery of Pterodactyles, the teeth might have been regarded as a link
+with the more ancient birds, rather than a crucial difference between
+birds and reptiles.
+
+All the specimens show a lateral temporal hole in the bones behind the
+eye, and this is found in no bird or mammal, and is typical of such
+reptiles as Hatteria. The quadrate bone may not be so decisive as Cuvier
+thought it to be, for its form is not unlike the quadrate of a bird, and
+different, so far as I have seen, from that of living reptiles. This
+region of the head is reptilian, and if it occurred in a bird the
+character would be as astonishing as was the discovery of teeth in
+extinct birds. These characters of the head are also found in fossil
+animals named Dinosaurs, in association with many resemblances to birds
+in their bones.
+
+The palate might conceivably be derived from that of Hatteria by
+enlarging the small opening in the middle line in that reptile till it
+extended forward between the vomera; but it is more easily compared with
+a bird, which the animal resembles in its beak, and in the position of
+the nares. Excepting certain Lizards, all true existing Reptiles have
+the nostrils far forward and bordered by two premaxillary bones instead
+of one intermaxillary, as in Birds and Ornithosaurs. If nothing were
+known of the animal but its head bones, it would be placed between
+Reptiles and Birds.
+
+
+
+
+CHAPTER IX
+
+THE BACKBONE, OR VERTEBRAL COLUMN
+
+
+The backbone is a more deep-seated part of the skeleton than the head.
+It is more protected by its position, and has less varied functions to
+perform. Therefore it varies less in distinctive character within the
+limits of each of the classes of vertebrate animals than either the head
+or limbs. It is divided into neck bones, the cervical vertebr�; back
+bones, the dorsal vertebr�; loin bones, the lumbar vertebr�; the sacrum,
+or sacral vertebr�, which support the hind limbs; and the tail. Of these
+parts the tail is the least important, though it reaches a length in
+existing reptiles which sometimes exceeds the whole of the remainder of
+the body, and includes hundreds of vertebr�. It attains its maximum
+among serpents and lizards. In frogs it is practically absent. In some
+of the higher mammals it is a rudiment, which does not extend beyond the
+soft parts of the body.
+
+
+THE NECK
+
+The neck is more liable to vary than the back, with the habit of life of
+the animal. And although mammals almost always preserve the same number
+of seven bones in the neck, the bones vary in length between the short
+condition of the porpoise, in which the neck is almost lost, and the
+long bones which form the neck of the Llama, though even these may be
+exceeded by some fossil reptiles like Tanystrophoeus. In many mammals
+the neck bones do not differ in length or size from those of the back.
+In others, like the Horse and Ox, they are much broader and larger.
+
+There is the same sort of variation in the bones of the neck among
+birds, some being slender like the Heron, others broad like the Swan.
+But there is also a singular variation in number of vertebral bones in a
+bird's neck. At fewest there are nine, which equals the exceptionally
+large number found among mammals in the neck of one of the Sloths.
+Usually birds have ten to fifteen cervical vertebr�, and in the Swan
+there are twenty-three. Most of the neck bones of birds are relatively
+long, and the length of the neck is often greater than the remainder of
+the vertebral column.
+
+Reptiles usually have short necks. The common Turtle has eight bones in
+the neck, ten in the back. The two regions are sharply defined by the
+dorsal shield. Their articular ends are sometimes cupped in front, in
+the neck, sometimes cupped behind, or convex at both ends, or even
+flattened, or the articulation may be made exceptionally by the neural
+arch alone. Nine is the largest number of neck bones in existing
+Lizards, and there are usually nine in Crocodiles; so that reptiles
+closely approach mammals in number of the neck bones. It is remarkable
+that the maximum number in a mammal and in living reptiles should
+coincide with the minimum number in birds. Therefore the number of
+cervical vertebr� as an attribute of Mammal, Bird, or Reptile, can only
+be important from its constancy.
+
+German naturalists affirm on clear evidence that the Solenhofen
+Pterodactyles have seven cervical vertebr�. In many specimens there can
+be no doubt about the number, because the neck bones are easily
+distinguished from those of the back by their size; but the number is
+not always easy to count.
+
+As in Birds, the first vertebra, or atlas, in Pterodactyles is extremely
+short, and is generally--if not always--blended with the much longer
+second vertebra, named the axis. The front of the atlas forms a small
+rounded cup to articulate with the rounded ball of the basioccipital
+bone at the back of the skull. The third and fourth vertebr� are longer,
+but the length visibly shortens in the sixth and seventh.
+
+Sometimes the vertebr� are slender and devoid of strong spinous
+processes. This is the condition in the little _Pterodactylus
+longirostris_ and in the comparatively large _Cycnorhamphus Fraasii_, in
+which there is a slight median ridge along the upper surface of the arch
+of the vertebra. This condition is paralleled in birds with long necks,
+especially wading birds such as the Heron. Other Ornithosaurs, such as
+Ornithocheirus from the Cretaceous rocks, have the neck much more
+massive. The vertebr� are flattened on the under side. The arch above
+the nervous matter of the spinal cord has a more or less considerable
+transverse expansion, and may even be as wide as long. These vertebr�
+have proportions and form such as may be seen in Vultures or in the
+Swan. In either case the form of the neck bones is more or less
+bird-like, and the neural spine may be elevated, especially in
+Pterodactyles with long tails.
+
+One of the most distinctive features of the neck bones of a bird is the
+way in which the cervical ribs are blended with the vertebr�. They are
+small, and each is often prolonged in a needle-like rod at the side of
+the neck bone.
+
+In Ornithocheirus the cervical rib similarly blends with the vertebra by
+two articulations, as in mammals, so that it might escape notice but for
+the channel of a blood vessel which is thus inclosed. In several of the
+older Pterodactyles from Solenhofen the ribs of the neck vertebr� remain
+separated, as in a Crocodile, though still bird-like in their form,
+anterior position, and mode of attachment. In Terrapins and Tortoises
+the long neck vertebr� have no cervical ribs.
+
+  [Illustration: FIG. 24  UNITED ATLAS AND AXIS OF ORNITHOCHEIRUS
+  (Cambridge Greensand)]
+
+The articular surfaces between the bodies of the vertebr�, in the neck,
+are transversely oval. The middle part of this articular joint is made
+by the body of the vertebra; its outer parts are in the neural arch. In
+front this surface is a hollow channel, often more depressed than in any
+other animals. The corresponding surface behind is convex, with a
+process on each side at its lower outer angles (Fig. 25). It is a
+modification of the cup-and-ball form of vertebral articulation, which
+at the present day is eminently reptilian. Serpents and Crocodiles have
+the articulations similarly vertical, but in both the form of the
+articulation is a circle. In Lizards the articular cup is usually rather
+wider than deep, when the cup and ball are developed in the vertebr�; it
+differs from the vertical condition in pterodactyles in being oblique
+and much narrower from side to side. Only among Crocodiles and Hatteria
+is there a double articulation for the cervical rib, though in neither
+order have rib or vertebra in the neck the bird-like proportions which
+are usual in these animals. Pterodactyles show no resemblance to birds
+in this vertebral articulation. A Bird has the corresponding surface
+concave from side to side in front, but it is also convex from above
+downward, producing what is known as the saddle-shaped form which is
+peculiarly avian, being found in existing birds except in part of the
+back in Penguins. It is faintly approximated to in one or two neck
+vertebr� in man. Professor Williston remarks that in the toothless
+Pterodactyles of Kansas the hinder ball of the vertebral articulation is
+continued downward and outward as a concave articulation upon the
+processes at its outer corners. There are no mammals with a cup-and-ball
+articulation between the vertebr�, so that for what it is worth the
+character now described in Ornithosaurs is reptilian, when judged by
+comparison with existing animals.
+
+  [Illustration: FIG. 25.  CERVICAL VERTEBRA OF ORNITHOCHEIRUS
+  From the Cambridge Greensand]
+
+Low down on each side of the vertebra, at the junction of its body with
+the neural arch, is a large ovate foramen, transversely elongated, and
+often a little impressed at the border, which is the entrance of the
+air cell into the bone. These foramina are often one-third of the length
+of the neck vertebr� in specimens from the Cambridge Greensand, where
+the neck bones vary from three-quarters of an inch to about two and a
+half inches in length, and in extreme forms are as wide as long. The
+width of the interspace between the foramina is one-half the width of
+the vertebr�, though this character varies with different genera and
+species. Several species from the Solenhofen Slate have the neck long
+and slender, on the type of the Flamingo. In others the neck is thick
+and short--in the _Scaphognathus crassirostris_ and _Pterodactylus
+spectabilis_. Some genera with slender necks have the bones preserved
+with a curved contour, such as might suggest a neck carried like that of
+a Llama or a Camel. The neck is occasionally preserved in a curve like a
+capital #S#, as though about to be darted forward like that of a bird in
+the act of striking its prey. The genera of Pterodactyles with short
+necks may have had as great mobility of neck as is found among birds
+named Ducks and Divers; but those Pterodactyles with stout necks, such
+as Dimorphodon and Ornithocheirus, in which the vertebr� are large,
+appear to have been built more for strength than activity, and the neck
+bones have been chiefly concerned in the muscular effort to use the
+fighting power of the jaws in the best way.
+
+
+THE BACK
+
+The region of the back in a Pterodactyle is short as compared with the
+neck, and relatively is never longer than the corresponding region in a
+bird. The shortness results partly from the short length of the
+vertebr�, each of which is about as long as wide. There is also a
+moderate number of bones in the back. In most skeletons from Solenhofen
+these vertebr� between the neck and girdle of hip bones number from
+twelve to sixteen. They have a general resemblance in form to the dorsal
+vertebr� in birds. The greatest number of such vertebr� in birds is
+eleven. The number is small because some of the later vertebr� in birds
+are overlapped by the bones of the hip girdle, which extend forward and
+cover them at the sides, so that they become blended with the sacrum.
+This region of the skeleton in the Dimorphodon from the Lias is
+remarkable for the length of the median process, named the neural spine,
+which is prolonged upward like the spines of the early dorsal vertebr�
+of Horses, Deer, and other mammals. In this character they differ from
+living reptiles, and parallel some Dinosaurs from the Weald. The bones
+of the back in Ornithocheirus from the Cambridge Greensand show the
+under side to be well rounded, so that the articular surfaces between
+the vertebr�, though still rather wider than deep, are much less
+depressed than in the region of the neck. The neural canal for the
+spinal cord has become larger and higher, and the sides of the bone are
+somewhat compressed. Strong transverse processes for the support of the
+ribs are elevated above the level of the neural canal, at the sides of
+vertebr� compressed on the under sides, and directed outward. Between
+these lateral horizontal platforms is the compressed median neural
+spine, which varies in vertical height. The articulation of the ribs is
+not seen clearly. Isolated ribs from the Stonesfield Slate have
+double-headed dorsal ribs, like those of birds. In some specimens from
+the Solenhofen Slate like the Scaphognathus, in the University Museum at
+Bonn, dorsal ribs appear to be attached by a notch in the transverse
+process of the dorsal vertebra, which resembles the condition in
+Crocodiles. Variations in the mode of attachment of ribs among mammals
+may show that character to be of subordinate importance. Von Meyer has
+described the first pair of ribs as frequently larger than the others,
+and there appear in Rhamphorhynchus to be examples preserved of the
+sternal ribs, which connect the dorsal ribs with the sternum. Six pairs
+have been counted. A more interesting feature in the ribs consists in
+the presence behind the sternum, which is shorter than the corresponding
+bone in most birds, of median sternal ribs. They are slender #V#-shaped
+bones in the middle line of the abdomen, which overlapped the ends of
+the dorsal ribs like the similar sternal bones of reptiles. Such
+structures are unknown among Birds and Mammals. There is no trace in the
+dorsal ribs of the claw-like process, which extends laterally from rib
+to rib as a marked feature in many birds. Its presence or absence may
+not be important, because it is represented by fibro-cartilage in the
+ribs of crocodiles, and may be a small cartilage near the head of the
+rib in serpents, and is only ossified in some ribs of the New Zealand
+reptile Hatteria. So that it might have been present in a fossil animal
+without being ossified and preserved. Although the structure is
+associated with birds, it is possibly also represented by the great bony
+plates which cover the ribs in Chelonians, and combine to form the
+shield which covers the turtle's back. The structure is as
+characteristic of reptiles as of birds, but is not necessarily
+associated with either.
+
+  [Illustration: FIG. 26
+
+  The upper figures show the side and back of a dorsal vertebra of
+  Ornithocheirus compared with corresponding views of the side and
+  back of a dorsal vertebra of a Crocodile]
+
+There are two remarkable modifications of the early dorsal vertebr� in
+some of the Cretaceous Pterodactyles. First, in the genus Ornithodesmus
+from the Weald the early dorsal vertebr� are blended together into a
+continuous mass, like that which is found in the corresponding region of
+the living Frigate-bird, only more consolidated, and similar to that
+consolidated structure found behind the dorsal vertebr�, known as the
+sacrum, made by the blending of the vertebr� into a solid mass which
+supports the hip bones. Secondly, in some of the Cretaceous genera of
+Pterodactyles of Europe and America the vertebr� in the front part of
+the back are similarly blended, but their union is less complete; and in
+genera Ornithocheirus and Ornithostoma--the former chiefly English, the
+latter chiefly American--the sides of the neural spines are flattened to
+form an oval articular surface on each side, which gives attachment to
+the flattened ends of their shoulder-blade bones named the scapul�. This
+condition is found in no other animals. Three vertebr� appear to have
+their neural arches thus united together. The structure so formed may be
+named the notarium to distinguish it from the sacrum.
+
+
+SACRUM
+
+For some mysterious reason the part of the backbone which lies between
+the bones of the hips and supports them is termed the sacrum. Among
+living reptiles the number of vertebr� in this region is usually two, as
+in lizards and crocodiles. There are other groups of fossil reptiles in
+which the number of sacral vertebr� is in some cases less and in other
+cases more. There is, perhaps, no group in which the sacrum makes a
+nearer approach to that of birds than is found among these
+Pterodactyles, although there are more sacral vertebr� in some
+Dinosaurs. In birds the sacral vertebr� number from five to twenty-two.
+In bats the number is from five to six. In some Solenhofen species, such
+as _Pterodactylus dubius_ and _P. Kochi_ and _P. grandipelvis_, the
+number is usually five or six. The vertebr� are completely blended. The
+pneumatic foramina in the sacrum, so far as they have been observed, are
+on the under sides of the transverse processes; while in the
+corresponding notarial structure in the shoulder girdle the foramina are
+in front of the transverse processes. Almost any placental mammal in
+which the vertebr� of the sacral region are anchylosed together has a
+similar sacrum, which differs from that of birds in the more complete
+individuality of the constituent bones remaining evident. The transverse
+processes in front of the sacrum are wider than in its hinder part; so
+that the pelvic bones which are attached to it converge as they extend
+backward, as among mammals. The bodies of the vertebr� forming the
+sacrum are similar in length to those of the back. Each transverse
+process is given off opposite the body of its own vertebra, but from a
+lower lateral position than in the region of the back, in which the
+vertebr� are free.
+
+  [Illustration: FIG. 27.  SACRUM OF RHAMPHORHYNCHUS
+
+  Showing the complete blending of the vertebr� and ribs as in a bird,
+  with the well-defined Iliac bones, produced chiefly in front of the
+  acetabulum for the head of the femur.]
+
+The hip bones are closely united with the sacrum by bony union, and
+rarely appear to come away from the sacral vertebr�, as among mammals
+and reptiles, though this happens with the Lias Pterodactyles. In the
+Stonesfield Slate and Solenhofen Slate the slender transverse processes
+from the vertebr� blend with the ilium of the hip girdle, and form a
+series of transverse foramina on each side of the bodies of the
+vertebr�. In the Cambridge Greensand genera the part of the ilium above
+the acetabulum for the articular head of the femur appears to be always
+broken away, so that the relation of the sacrum to the pelvis has not
+been observed. This character is no mark of affinity, but only shows
+that ossification obliterated sutures among these animals in the same
+way as among birds.
+
+The great difference between the sacrum of a Pterodactyle and that of a
+bird has been rendered intelligible by the excellent discussion of the
+sacral region in birds made by Professor Huxley. He showed that it is
+only the middle part of the sacrum of a chicken which corresponds to the
+true sacrum of a reptile, and comprises the five shortest of the
+vertebr�; while the four in front correspond to those of the lower part
+of the back, which either bear no ribs or very short ribs, and are known
+as the lumbar region in mammals, so that the lower part of the back
+becomes blended with the sacrum, and thus reduces the number of dorsal
+vertebr�. Similarly the five vertebr� which follow the true sacral
+vertebr� are originally part of the tail, and have been blended with the
+other vertebr� in front, in consequence of the extension along them of
+the bird's hip bones. This interpretation helps to account for the great
+length of the sacrum in many birds, and also explains in part the
+singular shortness of the tail in existing birds. The Ornithosaur sacrum
+has neither the lumbar nor the caudal portions of the sacrum of a bird.
+
+
+
+THE TAIL
+
+The tail is perhaps the least important part of the skeleton, since it
+varies in character and length in different genera. The short tails seen
+in typical pterodactyles include as few as ten vertebr� in
+_Pterodactylus grandipelvis_ and _P. Kochi_, and as many as fifteen
+vertebr� in _Pterodactylus longirostris_. The tails are more like those
+of mammals than existing birds, in which there are usually from six to
+ten vertebr� terminating in the ploughshare bone. But just as some
+fossil birds, like the Arch�opteryx, have about twenty long and slender
+vertebr� in the tail, so in the pterodactyle Rhamphorhynchus this region
+becomes greatly extended, and includes from thirty-eight to forty
+vertebr�. In Dimorphodon the tail vertebr� are slightly fewer. The
+earliest are very short, and then they become elongated to two or three
+times the length of the early tail vertebr�, and finally shorten again
+towards the extremity of the tail, where the bones are very slender. In
+all long-tailed Ornithosaurians the vertebr� are supported and bordered
+by slender ossified ligaments, which extend like threads down the tail,
+just as they do in Rats and many other mammals and in some lizards.
+
+Professor Marsh was able to show that the extremity of the tail in
+Rhamphorhynchus sometimes expands into a strong terminal caudal membrane
+of four-sided somewhat rhomboidal shape. He regards this membrane as
+having been placed vertically. It is supported by delicate processes
+which represent the neural spines of the vertebr� prolonged upward. They
+are about fifteen in number. A corresponding series of spines on the
+lower border, termed chevron bones, equally long, were given off from
+the junctions of the vertebr� on their under sides, and produced
+downward. This vertical appendage is of some interest because its
+expansion is like the tail of a fish. It suggests the possibility of
+having been used in a similar way to the caudal fin as an organ for
+locomotion in water, though it is possible that it may have also formed
+an organ used in flight for steering in the air.
+
+  [Illustration: FIG. 28.  EXTREMITY OF THE TAIL OF _RHAMPHORHYNCHUS
+  PHYLLURUS_ (MARSH)
+
+  Showing the processes on the upper and under sides of the vertebr�
+  which make the terminal leaf-like expansion]
+
+The tail vertebr� from the Cambridge Greensand are mostly found isolated
+or with not more than four joints in association. They are very like the
+slender type of neck vertebr� seen in long-necked pterodactyles, but are
+depressed, and though somewhat wider are not unlike the tail vertebr� of
+the Rhamphorhynchus. The pneumatic foramen in them is a mere puncture.
+They have no transverse processes or neural spines, nor indications of
+ribs, or chevron bones.
+
+The hindermost specimens of tail vertebr� observed have the neural arch
+preserved to the end, as among reptiles; whereas in mammals this arch
+becomes lost towards the end of the tail. The processes by which the
+vertebr� are yoked together are small. There is nothing to suggest that
+the tail was long, except the circumstance that the slender caudal
+vertebr� are almost as long as the stout cervical vertebr� in the same
+animal. No small caudal vertebr� have ever been found in the Cambridge
+Greensand. The tail is very short, according to Professor Williston, in
+the toothless Ornithostoma in the Chalk of Kansas.
+
+
+
+
+CHAPTER X
+
+THE HIP-GIRDLE AND HIND LIMB
+
+
+The bones of the hip-girdle form a basin which incloses and protects the
+abdominal vital organs. It consists on each side of a composite bone,
+the unnamed bones--_ossa innominata_ of the older anatomists--which are
+each attached to the sacrum on their inner side, and on the outer side
+give attachment to the hind limbs. As a rule three bones enter into the
+borders of this cup, termed the acetabulum, in which the head of the
+thigh bone, named the Femur, moves with a more or less rotary motion.
+
+There are a few exceptions in this division of the cup between three
+bones, chiefly among Salamanders and certain Frogs. In Crocodiles the
+bone below the acetabular cup is not divided into two parts. And in
+certain Plesiosaurs from the Oxford Clay--Mur�nosaurus--the actual
+articulation appears to be made by two bones--the ilium and ischium. The
+three bones which form each side of the pelvis are known as the ilium,
+or hip bone, sometimes termed the aitch bone; secondly, the ischium, or
+sitz bone, being the bone by which the body is supported in a sitting
+position; and thirdly the pubis, which is the bone in front of the
+acetabulum. The pubic bones meet in the middle line of the body on the
+under side of the pelvis in man, and on each side are partly separated
+from the ischia by a foramen, spoken of as the obturator foramen, which
+in Pterodactyles is minute and almost invisible, when it exists.
+
+There is often a fourth bony element in the pelvis. In some Salamanders
+a single cartilage is directed forward, and forked in front. According
+to Professor Huxley something of this kind is seen in the Dog. The pair
+of bones which extend forward in front of the pelvis in Crocodiles may
+be of the same kind, in which case they should be called prepubic bones.
+But among the lower mammals named marsupials a pouch is developed for
+the protection of the young and supported by two slender bones attached
+to the pubes, and these bones have long been known as marsupial bones.
+In a still lower group of mammalia named monotremata, which lay eggs,
+and in many ways approximate to reptiles and birds, stronger bones are
+developed on the front edge of the pubes, and termed prepubic bones.
+They do not support a marsupium.
+
+Naturalists have been uncertain as to the number of bones in the pelvis
+of Pterodactyles, because the bones blend together early in life, as in
+birds. Some follow the Amphibian nomenclature, and unite the ischium and
+pubis into one bone, which is then termed ischium, when the prepubis is
+termed the pubis, and regarded as removed from the acetabulum. There is
+no ground for this interpretation, for the sutures are clear between the
+three pelvic bones in the acetabulum in some specimens, like
+_Cycnorhamphus Fraasii_, from Solenhofen, and some examples of
+Ornithocheirus from the Cambridge Greensand. Pterodactyles all have
+prepubic bones, which are only known in Ornithorhynchus and Echidna
+among mammals, and are absent from the higher mammals and birds. They
+are unknown in any other existing animals, unless present in Crocodiles,
+in which ischium and pubis are always undivided. Therefore it is
+interesting to examine the characters of the Ornithosaurian pelvis.
+
+The acetabulum for the head of the femur is imperforate, being a simple
+oval basin, as in Chelonian reptiles and the higher Mammals. It never
+shows the mark of the ligamentous attachment to the head of the femur,
+which is seen in Mammals. In Birds the acetabulum is perforated, as in
+many of the fossils named Dinosaurs, and in Monotremata.
+
+  [Illustration: FIG. 29.  COMPARISON OF THE LEFT SIDE OF THE PELVIS IN
+  A BIRD AND A PTERODACTYLE]
+
+Secondly, the ilium is elongated, and extends quite as much in front of
+the acetabulum as behind it. The bone is not very deep in this front
+process. Among existing animals this relation of the bone is nearer to
+birds than to any other type, since birds alone have the ilium extended
+from the acetabulum in both directions. The form of the Pterodactyle
+ilium is usually that of the embryo bird, and its slender processes
+compare in relative length better with those of the unhatched fowl and
+Apteryx of New Zealand than with the plate-like form in adult birds.
+
+In mammals the ilium is directed forward, and even in the Cape ant-eater
+Orycteropus there is only an inappreciable production of the bone
+backward behind the acetabulum. Among reptiles the general position of
+the acetabulum is at the forward termination of the ilium, though the
+Crocodile has some extension of the bone in both directions, without
+forming distinct anterior and posterior processes. This anterior and
+posterior extension of the ilium is seen in the Theriodont reptiles of
+Russia and of South Africa, as well as in Dinosaurs.
+
+  [Illustration: FIG. 30.  LEFT PELVIC BONES WITH PREPUBIC BONE IN
+  _PTERODACTYLUS LONGIROSTRIS_]
+
+Thirdly, in all pterodactyles the ischium and pubis are more or less
+completely blended into a sheet of bone, unbroken by perforation, though
+there is usually a minute vascular foramen; or the lower border may be
+notched between the ischium and the pubis, as in some of the Solenhofen
+species, and the pubis does not reach the median line of the body. But
+in Dimorphodon the pelvic sheet of bone is unbroken by any notch or
+perforation. The notch between the ischium and pubis is well marked in
+_Pterodactylus longirostris_, and better marked in _Pterodactylus
+dubius_, _Cycnorhamphus Fraasii_, and Rhamphorhynchus. The fossil
+animals which appear to come nearest to the Pterodactyles in the
+structure of the pelvis are Theriodonts from the Permian rocks of
+Russia. The type known as Rhopalodon has the ilium less prolonged front
+and back, and is much deeper than in any Pterodactyle; but the
+acetabulum is imperforate, and the ischium and pubis are not always
+completely separated from each other by suture. In the pelvis referred
+to the Theriodont Deuterosaurus there is some approximation to the
+pelvis of Rhamphorhynchus and of _Pterodactylus dubius_ in the depth of
+the division between the pubis and ischium.
+
+  [Illustration: FIG. 31  PELVIS AND PREPUBIC BONES OF RHAMPHORHYNCHUS
+
+  On the left-hand side the two prepubic bones are separate. On the
+  right-hand they are united into a transverse bar which overlaps the
+  front of pelvis seen from the under side]
+
+There are three modifications of the Ornithosaurian pelvis. First, the
+type of Rhamphorhynchus, in which the pubis and ischium are inclined
+somewhat backward, and in which the two prepubic bones are triangular,
+and are often united together to form a transverse bow in front of the
+pubic region.
+
+Secondly, there is the ordinary form of pelvis in which the pubis and
+ischium usually unite with each other down their length, as in
+Dimorphodon, but sometimes, as in _Pterodactylus dubius_, divide
+immediately below the acetabulum. All these types possess the
+paddle-shaped prepubic bones, which are never united in the median line.
+
+Thirdly, there is the cretaceous form indicated by Ornithocheirus and
+Ornithostoma, in which the posterior half of the ilium is modified in a
+singular way, since it is more elevated towards the sacrum than the
+anterior half, suggesting the contour of the upper border of the ilium
+in a lizard. Without being reptilian--the anterior prolongation of the
+bone makes that impossible--it suggests the lizards. This type also
+possesses prepubic bones. They appear, according to Professor Williston,
+to be more like the paddle-shaped bones of Pterodactylus than like the
+angular bones in Rhamphorhynchus. The prepubic bones are united in the
+median line as in Rhamphorhynchus. But their median union in that genus
+favours the conclusion that the bones were united in the median line in
+all species, though they are only co-ossified in these two families.
+
+  [Illustration: FIG. 32.  THE PELVIC BONES OF AN ALLIGATOR SEEN FROM
+  BELOW
+
+  The bones in front are here regarded as prepubic, but are commonly
+  named pubic]
+
+This median union of the prepubic bones is a difference from those
+mammals like the Ornithorhynchus and Echidna, which approach nearest to
+the Reptilia. In them the prepubic bones have a long attachment to the
+front margin of the pubis, and extend their points forward without any
+tendency for the anterior extremities to approximate or unite. The
+marsupial mammals have the same character, keeping the marsupial bones
+completely distinct from each other at their free extremities. The only
+existing animals in which an approximation is found to the prepubic
+bones in Pterodactyles are Crocodiles, in bones which most writers term
+the pubic bones. This resemblance, without showing any strong affinity
+with the Crocodilia, indicates that Crocodiles have more in common with
+the fossil flying animals than any other group of existing reptiles; for
+other reptiles all want prepubic bones, or bones in front of the pubic
+region.
+
+
+THE HIND LIMB
+
+The hind limb is exceptionally long in proportion to the back. This is
+conspicuous in the skeletons of the short-tailed Pterodactyles, and is
+also seen in Dimorphodon. In Rhamphorhynchus the hind limb is relatively
+much shorter, so that the animal, when on all fours, may have had an
+appearance not unlike a Bat in similar position. The limb is
+exceptionally short in the little _Ptenodracon brevirostris_. The bones
+of the hind limb are exceptionally interesting. One remarkable feature
+common to all the specimens is the great elongation of the shin bones
+relatively to the thigh bones. The femur is sometimes little more than
+half the length of the tibia, and always shorter than that bone. The
+proportions are those of mammals and birds. Some mammals have the leg
+shorter than the thigh, but mammals and birds alone, among existing
+animals, have the proportions which characterise Pterodactyles. The
+foot appears to have been applied to the ground not always as in a bird,
+but more often in the manner of reptiles, or mammals in which the digits
+terminate in claws.
+
+
+THE FEMUR
+
+  [Illustration: FIG. 33.  THE FEMUR
+
+  On the right is a front view of femur of a bear. In the middle are
+  front and side views of the femur of Ornithocheirus. On the left is
+  the femur of Echidna. These comparisons illustrate the mammalian
+  characters of the Pterodactyle thigh bone]
+
+The thigh bone, on account of the small size of many of the specimens,
+is not always quite clear evidence as an indication of technical
+resemblance to other animals. The bone is always a little curved, has
+always a rounded, articular head, and rounded distal condyles. Its most
+remarkable features are shown in the large, well-preserved specimens
+from the Cambridge Greensand. The rounded, articular head is associated
+with a constricted neck to the bone, followed by a comparatively
+straight shaft with distal condyles, less thickened than in mammals. No
+bird is known, much less any reptile, with a femur like Ornithocheirus.
+Only among Mammals is a similar bone known with a distinct neck; and
+only a few mammals have the exceptional characters of the rounded head
+and constricted neck at all similar to the Cretaceous Pterodactyles. A
+few types, such as the higher apes, the Hyrax, and animals especially
+active in the hind limb, have a femur at all resembling the Pterodactyle
+in the pit for the obturator externus muscle, behind the trochanter
+major, such as is seen in a small femur from Ashwell. The femur varies
+in different genera, so as to suggest a number of mammalia rather than
+any particular animal for comparison. These approximations may be
+consequences of the ways in which the bones are used. When functional
+modifications of the skeleton are developed, so as to produce similar
+forms of bones, the muscles to which they give attachment, which act
+upon the bones, and determine their growth, are substantially the same.
+In the _Pterodactylus longirostris_ the femur corresponds in length to
+about eleven dorsal vertebr�. The end next the shin bone is less
+expanded than is usual among Mammals, and rather suggests an approach to
+the condition in Crocodiles, in the moderate thickness and breadth of
+the articular end, and the slight development of the terminal
+pulley-joint. One striking feature of the femur is the circumstance that
+the articular head, as compared with the distal end, is directed forward
+and very slightly inward and upward. So that allowing for the outward
+divergence of the pelvic bones, as they extend forward, there must have
+been a tendency to a knock-kneed approximation of the lower ends of the
+thigh bones, as in Mammals and Birds, rather than the outward divergence
+seen in Reptiles.
+
+Apparently the swing of the leg and foot, as it hung on the distal end
+of the femur, must have tended rather to an inward than to an outward
+direction, so that the feet might be put down upon the same straight
+line; this arrangement suggests rapid movement.
+
+  [Illustration: FIG. 34.  COMPARISON OF THE TIBIA AND FIBULA IN
+  ORNITHOSAUR AND VULTURE]
+
+
+TIBIA AND FIBULA
+
+In _Pterodactylus longirostris_ the tibia is slender, more than a fifth
+longer than the femur. A crest is never developed at the proximal end,
+like that seen in the Guillemot and Diver and other water birds. The
+bone is of comparatively uniform thickness down the shaft in most of the
+Solenhofen specimens, as in most birds. At the distal end the shin bone
+commonly has a rounded, articular termination, like that seen in birds.
+This is conspicuous in the _Pterodactylus grandis_. In other specimens
+the tarsal bones, which form this pulley, remain distinct from the
+tibia; and the upper row of these bones appears to consist of two
+bones, like those which in many Dinosaurs combine to form the
+pulley-like end of the tibia which represents the bird's drum-stick
+bone. They correspond with the ankle bones in man named astragalus and
+os calcis.
+
+Complete English specimens of tibia and fibula are found in the genus
+Dimorphodon from the Lias, in which the terminal pulley of the distal
+end has some expansion, and is placed forward towards the front of the
+tibia, as in some birds. The rounded surface of the pulley is rather
+better marked than in birds. The proximal end of the shaft is relatively
+stout, and is modified by the well-developed fibula, which is a short
+external splint bone limited to the upper half of the tibia, as in
+birds; but contributing with it to form the articular surface for the
+support of the lower end of the femur, taking a larger share in that
+work than in birds. Frequently there is no trace of the fibula visible
+in Solenhofen specimens as preserved; or it is extremely slender and
+bird-like, as in _Pterodactylus longirostris_. In Rhamphorhynchus it
+appears to extend the entire length of the tibia, as in Dinosaurs. In
+the specimens from the Cambridge Greensand there is indication of a
+small proximal crest to the tibia with a slight ridge, but no evidence
+that this is due to a separate ossification. The patella, or knee-cap,
+is not recognised in any fossil of the group. There is no indication of
+a fibula in the specimens thus far known from the Chalk rocks either of
+Kansas in America, or in England.
+
+The region of the tarsus varies from the circumstance that in many
+specimens the tibia terminates downward in a rounded pulley, like the
+drum-stick of a bird; while in other specimens this union of the
+proximal row of the tarsal bones with the tibia does not take place, and
+then there are two rows of separate tarsal bones, usually with two bones
+in each row. When the upper row is united with the tibia the lower row
+remains distinct from the metatarsus, though no one has examined these
+separate tarsal bones so as to define them.
+
+
+THE FOOT
+
+  [Illustration: FIG. 35.  METATARSUS AND DIGITS IN THREE TYPES OF
+  ORNITHOSAURS]
+
+The foot sometimes has four toes, and sometimes five. There are four
+somewhat elongated, slender metatarsal bones, which are separate from
+each other and never blended together, as in birds. There has been a
+suspicion that the metatarsal bones were separate in the young
+Arch�opteryx. In the young of many birds the row of tarsal bones at the
+proximal end of the metatarsus comes away, and there is a partial
+division between the metatarsal bones, though they remain united in the
+middle. And among Penguins, in which the foot bones are applied to the
+ground instead of being carried in the erect position of ordinary birds,
+there is always a partial separation between the metatarsal bones,
+though they become blended together. The Pterodactyle is therefore
+different from birds in preserving the bones distinct through life, and
+this character is more like Reptiles than Mammals. The individual bones
+are not like those of Dinosaurs, and diverge in Rhamphorhynchus as
+though the animals were web-footed. There is commonly a rudimentary
+fifth metatarsal. It is sometimes only a claw-shaped appendage, like
+that seen in the Crocodile. It is sometimes a short bone, completely
+formed, and carrying two phalanges in Solenhofen specimens: though no
+trace of these phalanges is seen in the large toothless Pterodactyles
+from the Cretaceous rocks of North America. In the _Pterodactylus
+longirostris_ the number of foot bones on the ordinary digits is two,
+three, four, five, as in lizards; but the short fifth metatarsal has
+only two toe bones. In Dimorphodon the fifth digit was bent upward, and
+supported a membrane for flight. There are slight variations in the
+number of foot bones. In the species _Pterodactylus scolopaciceps_ the
+number of bones in the toes follows the formula two, three, three, four.
+In _Pterodactylus micronyx_ the number is two, three, three, three. The
+terminal claws are much less developed than is usual with Birds; and
+there is a difference from Bats in the unequal length of the digits.
+Taken as a whole, the foot is perhaps more reptilian than avian, and in
+some genera is crocodilian.
+
+The foot is the light foot of an active animal. Von Meyer thought that
+the hind legs were too slender to enable the animal to walk on land; and
+Professor Williston, of the University of Kansas, remarks that the
+rudimentary claws and weak toes indicate that the animal could not have
+used the feet effectively for grasping, while the exceedingly free
+movement of the femur indicates great freedom of movement of the hind
+legs; and he concludes that the function of the legs was chiefly for
+guidance in flight through their control over the movements, and
+expresses his belief that the animal could not have stood upon the
+ground with its feet. There may be evidence to sustain other views. If
+the limb bones are reconstructed, they form limbs not wanting in
+elegance or length. If it is true, as Professor Williston suggests, that
+the weight of his largest animals with the head three feet long, and a
+stretch of wing of eighteen or nineteen feet, did not exceed twenty
+pounds, there can be no objection to regarding these animals as
+quadrupeds, or even as bipeds, on the ground of the limbs lacking the
+strength necessary to support the body. The slender toes of many birds,
+and even the two toes of the ostrich, may be thought to give less
+adequate support for those animals than the metatarsals and digits of
+Pterodactyles.
+
+
+
+
+CHAPTER XI
+
+SHOULDER-GIRDLE AND FORE LIMB
+
+
+STERNUM
+
+The sternum is always a distinguishing part of the bony structure of the
+breast. In Crocodiles it is a cartilage to which the sternal ribs unite;
+and upon its front portion a flat knife-like bone called the
+interclavicle is placed. In lizards like the Chameleon, it is a
+lozenge-shaped structure of thin bony texture, also bearing a long
+interclavicle, which supports the clavicular bones, named collar bones
+in man, which extend outward to the shoulder blades. Among mammals the
+sternum is usually narrow and flat, and often consists of many
+successive pieces in the middle line, on the under side of the body.
+Among Bats the anterior part is somewhat widened from side to side, to
+give attachment to the collar bones, but the sternum still remains a
+narrow bone, much narrower than in Dolphins, and not differing in
+character from many other Mammals, notwithstanding the Bat's power of
+flight. The bone develops a median keel for the attachment of the
+muscles of the breast, but something similar is seen in burrowing
+Insectivorous mammals like the Moles. So that, as Von Meyer remarked,
+the presence of a keel on the sternum is not in itself sufficient
+evidence to prove flight.
+
+Among birds the sternum is greatly developed. Broad and short in the
+Ostrich tribe, it is devoid of a keel; and therefore the keel, if
+present in a bird, is suggestive of flight. The keel is differently
+developed according to the mode of attachment of the several pectoral
+muscles which cover a bird's breast. In several water birds the keel is
+strongly developed in front, and dies away towards the hinder part of
+the sternum, as in the Cormorant and its allies. The sternum in German
+Pterodactyles is most nearly comparable to these birds.
+
+  [Illustration: FIG. 36.  COMPARISON OF THE STERNUM]
+
+In the Solenhofen Slate the sternum is fairly well preserved in many
+Ornithosaurs. It is relatively shorter than in birds, and is broader
+than long; but not very like the sternum of reptile or mammal in form.
+The keel is limited to the anterior part of the shield of the sternum,
+as in Merganser and the Cormorant, and is prolonged forward for some
+distance in advance of it. Von Meyer noticed the resemblance of this
+anterior process to the interclavicle of the Crocodile in position; but
+it is more like the keel of a bird's sternum, and is not a separate bone
+as in Reptiles. In Pterodactyles from the Cretaceous rocks, the side
+bones, called coracoids, are articulated to saddle-shaped surfaces at
+the hinder part of the base of this keel, which are parallel in
+Ornithocheirus, as in most birds, but overlap in Ornithodesmus, as in
+Herons and wading birds.
+
+  [Illustration: FIG. 37.  STERNUM IN ORNITHOCHEIRUS FROM THE CAMBRIDGE
+  GREENSAND
+
+  Showing the strong keel and the facets for the coracoid bones on its
+  hinder border above the lateral constrictions]
+
+The keel was pneumatic, and when broken is seen to be hollow, and
+appears to have been exceptionally high in Rhamphorhynchus, a genus in
+which the wing bones are greatly elongated. Von Meyer found in
+Rhamphorhynchus on each side of the sternum a separate lateral plate
+with six pairs of sternal ribs, which unite the sternum with the dorsal
+ribs, as in the young of some birds. The hinder surface of the sternum
+is imperfectly preserved in the toothless Pterodactyles of Kansas.
+Professor Williston states that the bone is extremely thin and
+pentagonal in outline, projecting in front of the coracoids, in a stout,
+blunt, keel-like process, similar to that seen in the Pterodactyles of
+the Cambridge Greensand. American specimens have not the same notch
+behind the articulation for the coracoid to separate it from the
+transverse lateral expansion of the sternal shield. The lateral margin
+in the Cambridge Greensand specimens figured by Professor Owen and
+myself is broken; but Professor Williston had the good fortune to find
+on the margin of the sternum the articular surfaces which gave
+attachment to the sternal ribs. The margin of the sternal bone thickens
+at these facets, four of which are preserved. The sternum in
+Ornithostoma was about four and a half inches long by less than five and
+a half inches wide. The median keel extends forward for rather less than
+two inches, while in the smaller Cambridge species of Ornithocheirus it
+extends forward for less than an inch and a half.
+
+A sternum of this kind is unlike that of any other animal, but has most
+in common with a bird; and may be regarded as indicating considerable
+power of flight. The bone cannot be entirely attributed to the effect of
+flight, since there is no such expanded sternal shield in Bats. The
+small number of sternal ribs is even more characteristic of birds than
+mammals or reptiles.
+
+
+THE SHOULDER-GIRDLE
+
+The bones which support the fore limb are one of the distinctive regions
+of the skeleton defining the animal's place in nature. Among most of the
+lower vertebrata, such as Amphibians and Reptiles, the girdle is a
+double arch--the arch of the collar bone or clavicles in front, and the
+arch of the shoulder-blade or scapula behind. The clavicular arch, when
+it exists, is formed of three or five parts--a medium bar named the
+interclavicle, external to which is a pair of bones called clavicles,
+reaching to the front of the scapul� when they are present; and
+occasionally there is a second pair of bones called supraclavicles,
+extending from the clavicles up the front margins of the scapul�. Thus
+the clavicular arch is placed in front of the scapular arch. The
+supraclavicles are absent from all living Reptiles, and the clavicles
+are absent from Crocodiles. The interclavicle is absent from all mammals
+except Echidna and Ornithorhynchus. Clavicles also may be absent in some
+orders of mammals. Hence the clavicular arch may be lost, though the
+collar bones are retained in man.
+
+The scapular arch also is more complicated and more important in the
+lower than in the higher vertebrata. It may include three bones on each
+side named coracoid, precoracoid, and scapula. But in most vertebrates
+the coracoid and precoracoid appear never to have been segmented so as
+to be separated from each other; and it is only among extinct types of
+reptiles, which appear to approximate to the Monotreme mammals, that
+separate precoracoid bones are found; though among most mammals,
+probably, there are stages of early development in which precoracoids
+are represented by small cartilages, though few mammals except Edentata
+like the Sloths and Ant-eaters, retain even the coracoids as distinct
+bones. Therefore, excepting the Edentata and the Monotremes, the
+distinctive feature of the mammalian shoulder-girdle appears to be that
+the limbs are supported by the shoulder-blades, termed the scapul�.
+
+Among reptiles there are several distinct types of shoulder-girdle.
+Chelonians possess a pair of bones termed coracoids which have no
+connexion with a sternum; and their scapul� are formed of two widely
+divergent bars, divided by a deeper notch than is found in any fossil
+reptiles. Among Lizards both scapula and coracoid are widely expanded,
+and the coracoid is always attached to the sternum. Chameleons have the
+blade of the scapula long and slender, but the coracoid is always as
+broad as it is long. Crocodiles have the bone more elongated, so that it
+has somewhat the aspect of a very strong first sternal rib when seen on
+the ventral face of the animal. The bone is perforated by a foramen,
+which would probably lie in the line of separation from the precoracoid
+if any such separation had ever taken place. The scapula, or
+shoulder-blade, of Crocodiles is a similar flat bone, very much shorter
+than the scapula of a Chameleon, and more like that of the New Zealand
+Hatteria. Thus there is very little in common between the several
+reptilian types of shoulder-girdle.
+
+  [Illustration: FIG. 38.  COMPARISON OF SCAPULA AND CORACOID IN THREE
+  PTERODACTYLES AND A BIRD]
+
+In birds the apparatus for the support of the wings has a far-off
+resemblance to the Crocodilian type. The coracoid bones, instead of
+being directed laterally outward and upward from the sternum, as among
+Crocodiles, are directed forward, so as to prolong the line of the
+breast bone, named the sternum. The bird's coracoid is sometimes
+flattened towards the breast bone among Swans and other birds; yet as a
+rule the coracoid is a slender bar, which combines with the still more
+slender and delicate blade of the scapula, which rests on the ribs, to
+make the articulation for the upper arm bone. Among reptiles the scapula
+and coracoid are more or less in the same straight line, as in the
+Ostrich, but in birds of flight they meet at an angle which is less than
+a right angle, and where they come in contact the external surface is
+thickened and excavated to make the articulation for the head of the
+humerus. There is nothing like this shoulder-girdle outside the class of
+birds, until it is compared with the corresponding structure in these
+extinct animals called Pterodactyles. The resemblance between the two is
+surprising. It is not merely the identity of form in the coracoid bone
+and the scapula, but the similar angle at which they meet and the
+similar position of the articulation for the humerus. Everything in the
+Pterodactyle's shoulder-girdle is bird-like, except the absence of the
+representative of the clavicles, that forked #V#-shaped bone of the bird
+which in scientific language is known as the furculum, and is popularly
+termed the "merry-thought." This kind of shoulder-girdle is found in the
+genera from the Lias and the Oolitic rocks, both of this country and
+Germany.
+
+In the Cretaceous rocks the scapula presents, in most cases, a different
+appearance. The coracoid is an elongated, somewhat triangular bone,
+compressed on the outer margin as in birds, but differing alike from
+birds and other Pterodactyles in not being prolonged forward beyond the
+articulation for the humerus. In these Cretaceous genera, toothed and
+toothless alike, the articulation for the upper arm bone truncates the
+extremity of the coracoid, so that the bone is less like that of a bird
+in this feature. Perhaps it shows a modification towards the crocodilian
+direction. The scapula, which unites with the coracoid at about a right
+angle, is similarly truncated by the articular surface for the humerus;
+but the bone is somewhat expanded immediately beyond the articulation,
+and compressed; and instead of being directed backward, it is directed
+inward over the ribs to articulate with the neural arches of the early
+dorsal vertebr� in the genera found in strata associated with the Chalk.
+As the bone approaches this articulation, it thickens and widens a
+little, becoming suddenly truncated by an ovate facet, which exactly
+corresponds to the transversely ovate impression, concave from front to
+back, which is seen in the neural arches of the dorsal vertebr� on which
+it fits. This condition is not present in all Cretaceous Pterodactyles.
+It does not occur in the Kansas fossil, named by Professor Marsh,
+Nyctodactylus. And it appears to be absent from the Pterodactyles of the
+English Weald, named Ornithodesmus.
+
+  [Illustration: FIG. 39.  THE NOTARIUM
+
+  An ossification which gives attachment to the scapul� seen in the
+  early dorsal vertebra of Ornithocheirus
+
+  (From the Cambridge Greensand)]
+
+  [Illustration: FIG. 40.  RESTORATION OF THE SHOULDER-GIRDLE IN THE
+  CRETACEOUS ORNITHOCHEIRUS
+
+  Showing how the scapul� articulate with a vertebra and the
+  articulation of the coracoids with the sternum. The humeral
+  articulation with the coracoid is unlike the condition shown
+  in other Ornithosaurs]
+
+There is no approach to this transverse position of the scapul� among
+birds. And while the form of the bones in the older genera of
+Ornithosaurs is singularly bird-like, the angular arrangement in this
+Cretaceous genus is obtained by closely approximating the articulations
+on the sternum, so that the coracoids extend outward as in reptiles,
+instead of forward as in birds; and the extremities of the scapul�
+similarly approximate towards each other. This rather recalls the
+relative positions of scapula and coracoid among crocodiles. If
+crocodile and bird had been primitive types of animals instead of
+surviving types, it might almost seem as though there had been a cunning
+and harmonious blending of one with the other in evolving this form of
+shoulder-girdle.
+
+
+THE FORE LIMB
+
+The bones of the fore limb, generally, correspond in length with the
+similar parts of the hind limb. The upper arm bone corresponds with the
+upper leg bone, and the fore-arm bone is as long as the fore-leg bone;
+then differences begin. The bones which correspond to the back of the
+hand in man, termed the metacarpus, are variable in length in
+Pterodactyles--sometimes very long and sometimes short. The wing
+metacarpal bone is always stout, and the others are slender. The
+extremity of the metacarpus was applied to the ground. Three small
+digits of the hand are developed from the three small metacarpal bones,
+and terminate in large claws.
+
+The great wing finger was bent backward, and only touched the ground
+where it fitted upon the wing metacarpal bone. It appears sometimes to
+have been as long as the entire vertebral column.
+
+Owing to the circumstance that the joint in the arm in Pterodactyles was
+not at the wrist as among birds, but between the metacarpus and the
+phalanges, it follows that the fore limb was longer than the hind limb
+when the metacarpus was long; but the difference would not interfere
+with the movements of the animal, either upon four feet or on two feet,
+for in bats and birds the disproportion in length is greater.
+
+
+HUMERUS OR UPPER ARM BONE
+
+The first bone in the fore-arm, the humerus, is remarkable chiefly for
+the compressed crescent form of its upper articular end, which is never
+rounded like the head of the upper arm bone in man, and secondly for the
+great development of the external process of bone near that end, termed
+the radial crest. Sir Richard Owen compared the bone to the humerus of
+both birds and crocodiles, but in its upper articular end the crocodile
+bone may be said to be more like a bird than it is like the
+Pterodactyle. In flying reptiles the articular surface next to the
+shoulder-girdle is somewhat saddle-shaped, being concave from side to
+side above and convex vertically, while most animals with which it can
+be compared have the articular head of the bone convex in both
+directions. A remarkable exception to this general rule is found in some
+fossil animals from South Africa, which, from resemblance to mammals in
+their teeth, have been termed Theriodonts. They sometimes have the head
+of the bone concave from side to side and convex in the vertical
+direction. To this condition Ornithorhynchus makes a slight
+approximation. The singular expansion of the structure called the radial
+crest finds no close parallel in reptiles, though Crocodiles have a
+moderate crest on the humerus in the same position; and in Theriodonts
+the radial crest extends much further down the shaft of the humerus. No
+bird has a radial crest of a similar kind, though it is prolonged some
+way down the shaft in Arch�opteryx. In Pterodactyles it sometimes
+terminates outward in a smooth, rounded surface, which might have been
+articular if any structure could have articulated with it. There is also
+a moderate expansion of the bone on the ulnar side in some
+Pterodactyles, so that the proximal end often incloses nearly
+three-fourths of an ovate outline. The termination of the radial crest
+is at the opposite end of this oval to the wider articular part of the
+head of the bone, in some specimens from the Cambridge Greensand. The
+radial crest is more extended in Rhamphorhynchus. All specimens of the
+humerus show a twist in the length of the bone, so that the end towards
+the fore-arm, which is wider than the shaft, makes a right angle with
+the radial crest on the proximal end, which is not seen in birds. The
+shaft of the humerus is always stouter than that of the femur, though
+different genera differ in this respect.
+
+The humerus in genera from rocks associated with the Chalk presents two
+modifications, chiefly seen in the characters of the distal end of the
+bone. One of these is a stout bone with a curiously truncated end where
+it joins the two bones of the fore-arm; and the other is more or less
+remarkable for the rounded form of the distal condyles. Both types show
+distinct articular surfaces. The inner one is somewhat oblique and
+concave, the outer one rounded; the two being separated by a concave
+channel, so that the ulna makes an oblique articulation with the bone as
+in birds, and the radius articulates by a more or less truncated or
+concave surface.
+
+  [Illustration: FIG. 41.  COMPARISON OF THE HUMERUS IN PTERODACTYLE AND
+  BIRD]
+
+
+ULNA AND RADIUS
+
+  [Illustration: FIG. 42.  COMPARISON OF THE BONES OF THE FORE-ARM IN
+  BIRD AND ORNITHOSAUR]
+
+The bones of the fore-arm are similar to each other in size, and if
+there be any difference between them the ulna is slightly the larger.
+There is some evidence that in Rhamphorhynchus the upper end of the ulna
+was placed behind the radius, probably in consequence of the mode of
+attachment of those bones to the humerus. The ulna abutted towards the
+inner and lower border, while the radius was towards the upper border,
+consequent upon the twist in the humerus. This condition corresponds
+substantially with the arrangement in birds, but differs from birds in
+the relatively more important part taken by the radius in making the
+articulation. The bones are compared in Dimorphodon with the Golden
+Eagle drawn of the same size (Fig. 42). In birds the ulna supports the
+great feathers of the wing, and this may account for the size of the
+bone. The ulna is best seen at its proximal end in the specimens from
+the Cambridge Greensand, where there is a terminal olecranon
+ossification forming an oblique articulation, which frequently comes
+away and is lost. It is sometimes well preserved, and indicated by a
+suture. The examples of ulna from the Lias show a slight expansion of
+the bone at both ends, and at the distal end toward the wrist the
+articulation is well defined, where the bone joins the carpus. The
+larger specimens of the bone are broken. The distal articular surface is
+only connected with the proximal end of the bone in small specimens: it
+always shows on the one margin a concavity, followed by a prominent
+boss, and an oblique articulation beyond the boss. On the side towards
+the radius, on the lower end of the shaft there is an angular ridge,
+which marks the line along which the ulna overlaps the radius. The
+lower end of the radius has a simple, slightly convex articulation,
+somewhat bean-shaped. No rotation of these bones on each other was
+possible as in man. There is a third bone in the fore-arm. This bone,
+named the pteroid, is commonly seen in skeletons from Solenhofen. It was
+regarded by Von Meyer as having supported the wing membrane in flight.
+Some writers have interpreted it as an essential part of the
+Pterodactyle skeleton, and Von Meyer thought that it might possibly
+indicate a fifth digit in the hand. The only existing structure at all
+like it is seen in the South African insectivorous mammal named
+_Chrysochloris capensis_, the golden mole, which also has three bones in
+the fore-arm, the third bone extending half-way up towards the humerus.
+In that animal the third bone appears to be behind the others and
+adjacent to the ulna. In the German fossils the pteroid articulated with
+a separate carpal or metacarpal bone, placed on the side of the arm
+adjacent to the radius, and the radius is always more inward than the
+ulna. If the view suggested by Von Meyer is adopted, this bone would be
+a first digit extending outward and backward towards the humerus. That
+view was adopted by Professor Marsh. It involves the interpretation of
+what has been termed the lateral carpal as the first metacarpal bone,
+which would be as short as that of a bird, but turned in the opposite
+direction backward. The first digit would then only carry one phalange,
+and would not terminate in a claw, but lie in the line of the tendon
+which supports the anterior wing membrane of a bird.
+
+The third bone in the fore-arm of Chrysochloris does not appear to
+correspond to a digit. The bone is on the opposite side of the arm to
+the similar bone of a Pterodactyle, and therefore cannot be the same
+structure in the Golden Mole. The interpretation which makes the pteroid
+bone the first digit has the merit of accounting for the fifth digit of
+the hand. All the structures of the hand are consistent with this view.
+The circumstance that the bone is rarely found in contact with the
+radius, but diverging from it, shows that it plays the same part in
+stretching the membrane in advance of the arm, that the fifth digit
+holds in supporting the larger wing membrane behind the arm.
+
+According to Professor Williston, the American toothless Pterodactyle
+Ornithostoma has but a single phalange on the corresponding first toe of
+the hind foot, and that bone he describes as long, cylindrical, gently
+curved, and bluntly pointed. There is some support for this
+interpretation; but I have not seen any English or German Pterodactyles
+with only one phalange in the first toe.
+
+The wing in Pterodactyles would thus be stretched between two fingers
+which are bent backward, the three intermediate digits terminating in
+claws.
+
+
+THE CARPUS
+
+The wrist bones in the reptilia usually consist of two rows. In
+Crocodiles, in the upper row there is a large inner and a small outer
+bone, behind which is a lunate bone, the remainder of the carpus being
+cartilaginous. Only one carpal is converted into bone in the lower row.
+It is placed immediately under the smaller upper carpal. In Chelonians,
+the turtle and tortoise group, the characters of the carpus vary with
+the family. In the upper row there are usually two short carpals, which
+may be blended, under the ulna; while the two under the radius are
+commonly united. The lower row is made up of several small bones.
+Lizards, too, usually have three bones in the proximal row and five
+smaller bones in the distal row.
+
+The correspondence of the distal carpals with the several metacarpal
+bones of the middle hand is a well-known feature of the structure of the
+wrist.
+
+Von Meyer remarks that the carpus is made up of two rows of small bones
+in the Solenhofen Pterodactyles; while in birds there is one row
+consisting of two bones. The structure of the carpus is not distinct in
+all German specimens; but in the short-tailed Solenhofen genera the
+bones in the two rows retain their individuality.
+
+In all the Cretaceous genera the carpal bones of each row are blended
+into a single bone, so that two bones are superimposed, which may be
+termed the proximal and distal carpals. One specimen shows by an
+indication of sutures the original division of the distal carpal into
+three bones; and the separated constituent bones are very rarely met
+with. Two bones of the three confluent elements contribute to the
+support of the wing metacarpal, and the third gives an articular
+attachment to the bone which extends laterally at the inner side of the
+carpus, which I now think may be the first metacarpal bone turned
+backward towards the humerus. The three component bones meet in the
+circular pneumatic foramen in the middle of the under side of the distal
+carpal. There is no indication of division of the proximal carpal in
+these genera into constituent bones.
+
+  [Illustration:  FIG. 43.  CARPUS FROM ORNITHOCHEIRUS
+  (Cambridge Greensand)]
+
+This condition is somewhat different from birds. In 1873 Dr. Rosenberg,
+of Dorpat, showed that there is in the bird a proximal carpal formed of
+two elements, and a distal carpal also formed of two elements. Therefore
+the two constituents of the distal carpal in the bird which blends in
+the mature animal with the metacarpus, forming the rounded pulley joint,
+may correspond with two of the three bones in the Cretaceous
+Pterodactyle _Ornithocheirus._
+
+The width of a proximal carpal rarely exceeds two inches, and that of a
+distal carpal is about an inch and three-quarters. Two such bones when
+in contact would not measure more than one inch in depth. The lower
+surface shows that the wing had some rotary movement upon the carpus
+outward and backward.
+
+
+METACARPUS
+
+  [Illustration: FIG. 44.  METACARPUS IN TWO ORNITHOSAURS]
+
+The metacarpus consists of bones which correspond to the back of the
+hand. The first digit of the hand in clawed animals has the metacarpal
+bone short, or shorter than the others. Among mammals metacarpal bones
+are sometimes greatly elongated; and a similar condition is found in
+Pterodactyles, in which the metacarpal bone may be much longer than the
+phalange which is attached to it. Two metacarpal bones appear to be
+singularly stouter than the others. The first bone of the first digit,
+if rightly determined, is much shorter than the others, and is, in fact,
+no longer than the carpus (Fig. 43). It is a flat oblong bone, attached
+to the inner side of the lower carpal, and instead of being prolonged
+distally in the same direction as the other metacarpal bones, is turned
+round and directed upward, so that its upper edge is flush with the base
+of the radius, and gives attachment to a bone which resembles a terminal
+phalange of the wing finger. According to this interpretation it is the
+first and only phalange in the first digit. The bone is often about half
+as long as the fore-arm, terminates upward in a point, is sometimes
+curved, and frequently diverges outward from the bones of the fore-arm,
+as preserved in the associated skeleton, being stretched towards the
+radial crest of the humerus. This mode of attachment of the supposed
+first metacarpal, which is true for all Cretaceous pterodactyles, has
+not been shown to be the same for all those from the Solenhofen Slate.
+There is no greater anomaly in this metacarpal and phalange on the
+inner side being bent backward, than there is in the wing finger being
+bent backward on the outer side. The three slender intervening digits
+extend forward between them, as though they were applied to the ground
+for walking.
+
+The bone which is usually known as the wing metacarpal is frequently
+stouter at the proximal end towards the carpus than towards the
+phalange. At the carpal end it is oblong and truncated, with a short
+middle process, which may have extended into the pit in the base of the
+carpal bone; while the distal terminal end is rounded exactly like a
+pulley. There is great difference in the length of the metacarpus. In
+the American genus Ornithostoma it is much longer than the fore-arm. In
+Rhamphorhynchus it is remarkably short, though perhaps scarcely so short
+as in Dimorphodon or in Scaphognathus. The largest Cretaceous examples
+are about two inches wide where they join the carpus. The bone is
+sometimes a little curved.
+
+Between the first and fifth or wing metacarpal are the three slender
+metacarpal bones which give attachment to the clawed digits. They bear
+much the same relation to the wing metacarpal that the large metatarsal
+of a Kangaroo has to the slender bones of the instep which are parallel
+to it.
+
+The facet for the wing metacarpal on the carpus is clearly recognised,
+but as a rule there is no surface with which the small metacarpals can
+be separately articulated. One or two exceptional specimens from the
+Cambridge Greensand appear to have not only surfaces for the wing
+metacarpal, but two much smaller articular surfaces, giving attachment
+to smaller metacarpals; while in one case there appears to be only one
+of these additional impressions. It is certain that all the animals from
+the Lias and Oolites have three clawed digits, but at present I have
+seen no evidence that there were three in the Cretaceous genera, though
+Professor Williston's statements and restoration appear to show that the
+toothless Pterodactyles have three. Another difference from the Oolitic
+types, according to Professor Williston, is in the length of the slender
+metacarpals of the clawed phalanges being about one-third that of the
+wing metacarpal, but this is probably due to imperfect ossification at
+the proximal end; for at the distal end the bones all terminated on the
+same level, showing that the four outer digits were applied to the
+ground to support the weight of the body. The corresponding bone in the
+Horse and Oxen is carried erect, so as to be in a vertical line with the
+bones of the fore-arm; and the same position prevails usually, though
+not invariably, with the corresponding bone in the hind limb, while in
+many clawed mammals the metacarpus and metatarsus are both applied upon
+the ground. In Pterodactyles the metatarsal bones are preserved in the
+rock in the same straight line with the smaller bones of the foot, or
+make an angle with the shin bone, leading to the conviction that the
+bones of the foot were applied to the ground as in Man, and sometimes as
+in the Dog, and were thus modified for leaping. Just as the human
+metacarpus is extended in the same line with the bones of the fore-arm,
+and the movement of jointing occurs where the fingers join the
+metacarpus, so Pterodactyles also had these bones differently modified
+in the fore and hind limbs for the functions of life. The result is to
+lengthen the fore limb as compared with the hind limb by introducing
+into it an elevation above the ground which corresponds to the length of
+the metacarpus, always supposing that the animal commonly assumed the
+position of a quadruped when upon the earth's surface.
+
+This position of the metacarpus is a remarkable difference from Birds,
+because when the bird's wing is at rest it is folded into three
+portions. The upper arm bone extends backward, the bones of the fore-arm
+are bent upon it so as to extend forward, and then at the wrist the
+third portion, which includes the metacarpus and finger bones, is bent
+backward. So that the metacarpus in the Pterodactyle differs from birds
+in being in the same line as the bones of the fore-arm, whereas in birds
+it is in the same line with the digit bones of the hand. It is worthy of
+remark that in Bats, which are so suggestive of Pterodactyles in some
+features of the hand, the metacarpals and phalanges are in the same
+straight line; so that in this respect the bat is more like the bird.
+But Pterodactyles in the relation of these bones to flight are quite
+unlike any other animal, and have nothing in common with the existing
+animals named Reptiles.
+
+
+THE HAND
+
+From what has just been said it follows that the construction of the
+hand is unique. It may be contrasted with the foot of a bird. The bone
+which is called, in the language of anatomists, the tarso-metatarsus,
+and is usually free from feathers and covered with skin, is commonly
+carried erect in birds, so that the whole body is supported upon it; and
+from it the toes diverge outward. It is formed in birds of three
+separate bones blended together. In the fore limb of the Pterodactyle
+the metacarpus has the same relation to the bones of the fore-arm that
+the metatarsus has to the corresponding bones of the leg in a bird. But
+the three metacarpal bones in the Pterodactyle remain distinct from each
+other, perhaps because the main work of that region of the skeleton has
+devolved upon the digit called the wing finger, which is not recognised
+in the bird. In the Pterodactyles from the Solenhofen Slate there is a
+progressive number of phalanges in the three small digits of the hand,
+which were applied to the ground. This number in the great majority of
+species follows the formula of two bones in the first, three bones in
+second, and four in the third; so that in the innermost of the clawed
+digits only one bone intervenes between the metacarpal and the claw. The
+fingers slightly increase in length with increase in number of bones
+which form them.
+
+  [Illustration: FIG. 45.  CLAW PHALANGE FROM THE HAND IN
+  ORNITHOCHEIRUS. (Half natural size)]
+
+  [Illustration: FIG. 46.  METACARPUS AND DIGITS OF THE HAND IN BIRDS
+  WITH CLAWS]
+
+The terminal claw bones are unlike the claws of Birds or Reptiles. They
+are compressed from side to side, and extremely deep and strong, with
+evidence of powerful attachment for ligaments, so that they rather
+resemble in their form and large size the claws of some of the
+carnivorous fossil reptiles, often grouped as Dinosauria, such as have
+been termed Aristosuchus and Megalosaurus. In the hand of the Ostrich
+the first and second digits terminate in claws, while the third is
+without a claw. But these claws of the Ostrich and other birds are
+slender, curved, and rather feeble organs. In the Arch�opteryx, a fossil
+bird which agrees with the Pterodactyles in retaining the separate
+condition of the metacarpal bones and in having the same number of
+phalanges in two of the fingers of the fore limb, the terminal claws are
+rather more compressed from side to side, and stronger than in the
+Ostrich, but not nearly so strong as in the Pterodactyle. The
+Arch�opteryx differs from the Pterodactyle in having no trace of a wing
+finger. The first metacarpal bone is short, as in all birds; and the
+first phalange scarcely lengthens that segment of the first digit of the
+Bird's hand to the same length as the other metacarpal bones. It
+therefore was not bent backward like the first digit in Pterodactyles.
+The wing finger, from which the genius of Cuvier selected the scientific
+name--Pterodactyle--for these fossils, yields their most distinctive
+character. It is a feature which could only be partly paralleled in the
+Bat, by making changes of structure which would remove every support to
+the wing but the outermost digit of that animal's hand. In the Bat's
+hand the membrane for flight is extended chiefly by four diverging
+metacarpal bones. There are only two or three phalanges in each digit in
+its four wing fingers. In Pterodactyles the metacarpal bones are, as we
+have seen, arranged in close contact, and take no part in stretching the
+wing.
+
+
+THE WING FINGER
+
+In Birds there is nothing whatever to represent the wing finger of the
+Pterodactyle, for it is an organ external to the finger bones of the
+bird, and contains four phalanges. The first phalange is quite different
+from the others. Its length is astonishing when compared with the small
+phalanges of the clawed fingers. The articular surface, which joins on
+to the wing metacarpal bone, is a concave articulation, which fits the
+pulley in which that bone ends. The pulley articulation admits of an
+extension movement in one direction only. Many specimens show the wing
+finger to be folded up so as to extend backward. The whole finger is
+preserved in other specimens straightened out so as to be in line with
+the metacarpus. This condition is well seen in Professor Marsh's
+specimen of Rhamphorhynchus, which has the wing membrane preserved, in
+which all bones of the fore-arm metacarpus and wing finger are extended
+in a continuous curve. The outer surface of the end of the first bone of
+the wing finger overlaps the wing metacarpal, so that a maximum of
+strength and resistance is provided in the bony structures by which the
+wing is supported. There is, therefore, in flight only one angular bend
+in the limb, and that is between the upper arm bone and the fore-arm.
+
+An immense pneumatic foramen is situate in a groove on the under side of
+the upper end of the first phalange in Ornithocheirus, but is absent in
+specimens from the Kimeridge clay. This bone is long and stout. It
+terminates at the lower end in an obliquely truncated articular surface.
+Specimens occur in the Cambridge Greensand which are 2 inches broad at
+the upper end and nearly 1-1/2 inch wide at the lower end. An imperfect
+bone from the Chalk is 14-1/2 inches long. The bones are all flattened.
+Specimens from the Chalk of Kansas at Munich are 28 inches long. The
+second phalange is concave at the upper articular end and convex in the
+longer direction at the lower end. The articular points of union between
+the several phalanges form prominences on the under side of the finger
+in consequence of the adjacent bones being a little widened at their
+junction. It should be mentioned that there is a proximal epiphysis or
+separate bone to the first phalange, adjacent to the pulley joint of the
+metacarpal bone, which is like the separate olecranon process of the
+ulna of the fore-arm. It sometimes comes away in specimens from the
+Chalk and Cambridge Greensand, leaving a large circular pit with a
+depressed narrow border. On the outer side of this process is a rounded
+boss, which may possibly have supported the bone, if it were applied to
+the ground with the wing folded up, like the wing of a Bat directed
+upward and backward at the animal's side.
+
+The four bones of the wing finger usually decrease progressively in
+length, so that in Rhamphorhynchus, in which the length of the animal's
+head only slightly exceeds 3-1/2 inches, the first phalange is nearly as
+long, the second phalange is about 3-1/4 inches, the third 2-3/4 inches,
+and the fourth a little over 2 inches. Thus the entire length of the
+four phalanges slightly exceeds 11 inches, or rather more than three
+times the length of the head. But the fore-arm and metacarpus in this
+type only measure 3 inches. Therefore the entire spread of wings could
+not have been more than 2 feet 9 inches.
+
+The largest Ornithosaur in which accurate measurements have been made is
+the toothless Pterodactyle Ornithostoma, also named Pteranodon, from
+North America. In that type the head appears to have been about 3 or 4
+feet long, and the wing finger exceeded 5 feet; while the length of the
+fore-arm and metacarpus exceeded 3 feet. The width of the body would not
+have been more than 1 foot. The length of the short humerus, which was
+about 11 inches, did not add greatly to the stretch of the wing; so that
+the spread of the wings as stretched in flight may be given as probably
+not exceeding 17 or 18 feet. A fine example of the wing bones of this
+animal quite as large has been obtained by the (British Museum Natural
+History). Many years ago, on very fragmentary materials, I estimated the
+wings in the English Cretaceous Ornithocheirus as probably having a
+stretch of 20 feet in the largest specimens, basing the calculation
+partly upon the extent of the longest wings in existing birds relatively
+to their bones, and partly upon the size of the largest associated bones
+which were then known.
+
+
+
+
+CHAPTER XII
+
+EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS
+
+
+Such are the more remarkable characters of the bones in a type of animal
+life which was more anomalous than any other which peopled the earth in
+the Secondary Epoch of geological time. Its skeleton in different parts
+resembles Reptiles, Birds, and Mammals; with modifications and
+combinations so singular that they might have been deemed impossible if
+Nature's power of varying the skeleton could be limited. Since
+Ornithosaurs were provided with wings, we may believe the animals to
+some extent to have resembled birds in habit. Their modes of progression
+were more varied, for the structures indicate an equal capacity for
+movement on land as a biped, or as a quadruped, with movement in the
+air. There is little evidence to support the idea that they were usually
+aquatic animals. The majority of birds which frequent the water have
+their bodies stored with fat and the bones of their extremities filled
+with marrow. And a bird's marrow bones are stouter and stronger than
+those which are filled with air. There are few, if any, bones of
+Pterodactyles so thick as to suggest the conclusion that they contained
+marrow, and the bones of the extremities appear to have been
+constructed on the lightest type found among terrestrial birds. Their
+thinness, except in a few specimens from the Wealden rocks, is
+marvellous; and all the later Pterodactyles show the arrangement, as in
+birds, by which air from the lungs is conveyed to the principal bones.
+No Pterodactyle has shown any trace of the web-footed condition seen in
+birds which swim on the water, unless the diverging bones of the hind
+foot in Rhamphorhynchus supports that inference. The bones of the hind
+foot are relatively small, and if it were not that a bird stands easily
+upon one foot, might be considered scarcely adequate to support the
+animal in the position which terrestrial birds usually occupy. Yet, as
+compared with the length and breadth of the foot in an Ostrich, the toes
+of an Ornithosaur are seen to be ample for support. These facts appear
+to discourage the idea that the animals were equally at home on land and
+water, and in air.
+
+Some light may be thrown upon the animal's habits by the geological
+circumstances under which the remains are found. The Pterodactyle named
+Dimorphodon, from the Lias of the south of England, is associated with
+evidences of terrestrial land animals, the best known of which is
+Scelidosaurus, an armoured Dinosaur adapted by its limbs for progression
+on land. And the Pterodactyle Campylognathus, from the Lias of Whitby,
+is associated with trunks of coniferous trees and remains of Insects. So
+that the occurrence of Pterodactyles in a marine stratum is not
+inconsistent with their having been transported by streams from off the
+old land surface of the Lias, on which coniferous trees grew and
+Dinosaurs lived.
+
+Similar considerations apply to the occurrence of the Rhamphocephalus in
+the Stonesfield Slate of England. The deposit is not only formed in
+shallow water, but contains terrestrial Insects, a variety of land
+plants, and many Reptiles and other animals which lived upon land. The
+specimens from the Purbeck beds, again, are in strata which yield a
+multitude of the spoils of a nearly adjacent land surface; while the
+numerous remains found in the marine Solenhofen Slate in Germany are
+similarly associated with abundant evidences of varied types of
+terrestrial life. The evidence grows in force from its cumulative
+character. The Wealden beds, which yield many terrestrial reptiles and
+so much evidence of terrestrial vegetation, and shallow-water conditions
+of disposition, have afforded important Pterodactyle remains from the
+Isle of Wight and Sussex.
+
+The chief English deposit in which these fossils are found, the Upper
+Greensand, has afforded thousands of bones, battered and broken on a
+shore, where they have lain in little associated groups of remains,
+often becoming overgrown with small marine shells. Side by side with
+them are found bones of true terrestrial Lizards and Crocodiles of the
+type of the Gavial of the Indian rivers, many terrestrial Dinosaurs, and
+other evidences of land life, including fossil resins, such as are met
+with in the form of amber or copal at the present day.
+
+The great bones of Pterodactyles found in the Chalk of Kent, near
+Rochester, became entombed, beyond question, far from a land surface.
+There is nothing to show whether the animals died on land and were
+drifted out to sea like the timber which is found water-logged and
+sunken after being drilled by the ship-worm (Teredo) of that epoch.
+Seeing the power of flight which the animal possessed, storms may have
+struck down travellers from time to time, when far from land.
+
+Evidence of habit of another kind may be found in their teeth. They are
+brightly enamelled, sharp, formidable; and are frequently long,
+overlapping the sides of the jaws. They are organs which are often
+better adapted for grasping than for tearing, as may be seen in the
+inclined teeth of Rhamphocephalus of the Stonesfield Slate; and better
+adapted for killing than tearing, from their piercing forms and cutting
+edges, in genera like Ornithocheirus of the Greensand. The manner in
+which the teeth were implanted and carried is better paralleled by the
+fish-eating crocodile of Indian rivers than by the flesh-eating
+crocodiles, or Muggers, which live indifferently in rivers and the sea.
+As the Kingfisher finds its food (see Fig. 20) from the surface of the
+water without being in the common sense of the term a water bird, so
+some Pterodactyles may have fed on fish, for which their teeth are well
+adapted, both in the stream and by the shore.
+
+A Pterodactyle's teeth vary a good deal in appearance. The few large
+teeth in the front of the jaw in Dimorphodon, associated with the many
+small vertical teeth placed further backward, suggest that the taking of
+food may have been a process requiring leisure, since the hinder teeth
+adapted to mincing the animal's meat are extremely small. The way in
+which the teeth are shaped and arranged differs with the genera. In
+Pterodactylus they are short and broad and few, placed for the most part
+towards the front of the jaws. Their lancet-shaped form indicates a
+shear-like action adapted to dividing flesh. In the associated genus
+Rhamphorhynchus the teeth are absent from the extremity of the jaw, are
+slender, pointed, spaced far apart, and extend far backward. When the
+jaws of the Rhamphorhynchus are brought together there is always a gap
+between them in front, which has led to belief that the teeth were
+replaced by some kind of horny armature which has perished. In the
+long-nosed English type of Ornithocheirus the jaws are compressed
+together, so that the teeth of the opposite sides are parallel to each
+other, with the margins well filled with teeth, which are never in close
+contact, though occasionally closer and larger in front, in some of the
+forms with thick truncated snouts.
+
+It is not the least interesting circumstance of the dentition of
+Pterodactyles that, associated in the same deposits with these most
+recent genera with teeth powerfully developed, there is a genus named
+Ornithostoma from the resemblance of its mouth to that of a bird in
+being entirely devoid of teeth. It is scarcely possible to distinguish
+the remains of the toothed and toothless skeletons except in the dentary
+character of the jaws. There is no evidence that the toothless types
+ever possessed a tooth of any sort. They were first found in fragments
+in England in the Cambridge Greensand, but were afterwards met with in
+great abundance in the Chalk of Kansas, where the same animals were
+named Pteranodon. A jaw so entirely bird-like suggests that the
+digestive organs of Pterodactyles may in such toothless forms at least
+have been characterised by a gizzard, which is so distinctive of Birds.
+The absence of teeth in the Great Ant-eater and some other allied
+Mammals has transferred the function which teeth usually perform to the
+stomach, one part of which becomes greatly thickened and muscular,
+adapting itself to the work which it has to perform. It is probable that
+the gizzard may be developed in relation to the necessities which food
+creates, since even Trout, feeding on the shell-fish in some Irish
+lochs, acquire such a thickened muscular stomach, and a like
+modification is recorded in other fishes as produced by food.
+
+Closely connected with an animal's habits is the protection to the body
+which is afforded by the skin. In Pterodactyles the evidence of the
+condition of the skin is scanty, and mostly negative. Sometimes the
+dense, smooth texture of the jaw bones indicates a covering like the
+skin of a Lizard or the hinder part of the jaw of a Bird. Some jaws from
+the Cambridge Greensand have the bone channeled over its surface by
+minute blood vessels which have impressed themselves into the bone more
+easily than into its covering. Thus in the species of Ornithocheirus
+distinguished as _microdon_ the palate is absolutely smooth, while in
+the species named _mach�rorhynchus_ it is marked by parallel impressed
+vascular grooves which diverge from the median line. This condition
+clearly indicates a difference in the covering of the bone, and that in
+the latter species the covering had fewer blood vessels and more horny
+protection than in the other. The tissue may not have been of firmer
+consistence than in the palate of Mammals. The extremity of the beak is
+often as full of blood vessels as the jaw of a Turtle or Crocodile.
+
+
+COVERING OF THE BODY
+
+There is no trace even in specimens from the Solenhofen or Stonesfield
+Slate of any covering to the body. There are no specimens preserved like
+mummies, and although the substance of the wings is found there is no
+trace of fur or feathers, bones, or scales on the skin. The only example
+in which there is even an appearance suggesting feathers is in the
+beautiful Scaphognathus at Bonn, and upon portions of the wing membrane
+of that specimen are preserved a very few small short and apparently
+tubular bodies, which have a suggestive resemblance to the quills of
+small undeveloped feathers. Such evidences have been diligently sought
+for. Professor Marsh, after examining the wing membranes of his specimen
+of Rhamphorhynchus from Solenhofen, stated that the wings were partially
+folded and naturally contracted into folds, and that the surface of the
+tissue is marked by delicate stri�, which might easily be taken at first
+sight for a thin coating of hair. Closer investigation proved the
+markings to be minute wrinkles on the under surface of the wing
+membrane. This negative evidence has considerable value, because the
+Solenhofen Slate has preserved in the two known examples of the bird
+Arch�opteryx beautiful details of the structure of the larger feathers
+concerned in flight. It has preserved many structures far more delicate.
+There is, therefore, reason for believing that if the skin had possessed
+any covering like one of those found in existing vertebrate animals, it
+could scarcely have escaped detection in the numerous undisturbed
+skeletons of Pterodactyles which have been examined.
+
+The absence of a recognisable covering to the skin in a fossil state
+cannot be accepted as conclusive evidence of the temperature, habits, or
+affinities of the animal. Although Mammalia are almost entirely clothed
+with dense hair, which has never been found in a recognisable condition
+in a fossil state in any specimen of Tertiary age, one entire order, the
+Cetacea, show in the smooth hairless skins of Whales and Porpoises that
+the class may part with the typical characteristic covering without loss
+of temperature and without intelligible cause. That the absence of hair
+is not due to the aquatic conditions of rivers or sea is proved by other
+marine Mammals, like Seals, having the skin clothed with a dense growth
+of hair, which is not surpassed in any other order. The fineness of the
+growth of hair in Man gives a superficial appearance of the skin being
+imperfectly clothed, and a similar skin in a fossil state might give the
+impression that it was devoid of hair. There are many Mammals in which
+the skin is scantily clothed with hair as the animal grows old. Neither
+the Elephant nor the Armadillo in a fossil state would be likely to have
+the hair preserved, for the growth is thin on the bony shields of the
+living Armadilloes. Yet the difficulty need be no more inherent in the
+nature of hair than in that of feathers, since the hair of the Mammoth
+and Rhinoceros has been completely preserved upon their skins in the
+tundras of Siberia, densely clothing the body. This may go to show that
+the Pterodactyle possessed a thin covering of hair, or, more probably,
+that hair was absent. Since Reptiles are equally variable in the
+clothing of the skin with bony or horny plates, and in sometimes having
+no such protection, it may not appear singular that the skin in
+Ornithosaurs has hitherto given no evidence of a covering. From analogy
+a covering might have been expected; feathers of Birds and hair of
+Mammals are non-conducting coverings suited to arrest the loss of heat.
+
+With the evidence, such as it is, of resemblance of Ornithosaurs to
+Birds in some features of respiration and flight, a covering to the skin
+might have been expected. Yet the covering may not be necessary to a
+high temperature of the blood. Since Dr. John Davy made his observations
+it has been known that the temperature of the Tunny, above 90�
+Fahrenheit, is as warm as the African scaly ant-eater named the
+Pangolin, which has the body more amply protected by its covering. This
+illustration also shows that hot blood may be produced without a
+four-celled heart, with which it is usually associated, and that even if
+the skin in Pterodactyles was absolutely naked an active life and an
+abundant supply of blood could have given the animal a high temperature.
+
+The circumstance that in several individuals the substance of the wing
+membrane is preserved would appear to indicate either that it was
+exceptionally stout when there would have been small chance of resisting
+decomposition, or that its preservation is due to a covering which once
+existed of fur or down or other clothing substance, which has proved
+more durable than the skin itself.
+
+  [Illustration: FIG. 48.  REMAINS OF DIMORPHODON FROM THE LIAS OF LYME
+  REGIS
+
+  SHOWING THE SKULL, NECK, BACK AND SOME OF THE LONGER BONES OF THE
+  SKELETON
+
+  _From a slab in the British Museum (Natural History)_]
+
+
+
+
+CHAPTER XIII
+
+ANCIENT ORNITHOSAURS FROM THE LIAS
+
+
+Cuvier's discourse on the revolutions of the Earth made the Pterodactyle
+known to English readers early in the nineteenth century. Dr. Buckland,
+the distinguished professor of Geology at Oxford, discovered in 1829 a
+far larger specimen in the Lias of Lyme Regis, and it became known by a
+figure published by the Geological Society, and by the description in
+his famous Bridgewater Treatise, p. 164. This animal was tantalising in
+imperfect preservation. The bones were scattered in the clay, so as to
+give no idea of the animal's aspect. Knowledge of its limbs and body has
+been gradually acquired; and now, for some years, the tail and most
+parts of the skeleton have been well known in this oldest and most
+interesting British Pterodactyle.
+
+Sir Richard Owen after some time separated the fossil as a distinct
+genus, named Dimorphodon; for it was in many ways unlike the
+Pterodactyles described from Bavaria. The name Dimorphodon indicated the
+two distinct kinds of teeth in the jaws, a character which is still
+unparalleled among Pterodactyles of newer age. There are a few large
+pointed, piercing and tearing teeth in the front of the jaws, with
+smaller teeth further back, placed among the tearing teeth in the upper
+jaw; while in the lower jaw the small teeth are continuous, close-set,
+and form a fine cutting edge like a saw.
+
+  [Illustration: FIG. 49.  LEFT SIDE OF DIMORPHODON (RESTORED) AT REST]
+
+The Dimorphodon has a short beak, a deep head, and deep lower jaw, which
+is overlapped by the cheek bones. The side of the head is occupied by
+four vacuities, separated by narrow bars of bone. First, in front, is
+the immense opening for the nostril, triangular in form, with the long
+upper side following the rounded curve of the face. A large triangular
+opening intervenes between the nose hole and the eye hole, scarcely
+smaller than the former, but much larger than the orbit of the eye. The
+eye hole is shaped like a kite or inverted pear. Further back still is a
+narrower vertical opening known as the lateral or inferior temporal
+vacuity. The back of the head is badly preserved. The two principal
+skulls differ in depth, probably from the strains under which they were
+pressed flat in the clay. A singular detail of structure is found in the
+extremity of the lower jaw, which is turned slightly downward, and
+terminates in a short toothless point. The head of Dimorphodon is
+about eight inches long.
+
+  [Illustration: FIG. 50.  DIMORPHODON MACRONYX
+  RESTORED FORM OF THE ANIMAL]
+
+The neck bones are of suitable stoutness and width to support the head.
+The bones are yoked together by strong processes. The neck was about 6
+inches long, did not include more than seven bones, and appeared short
+owing only to the depth and size of the head. The length of the backbone
+which supported the ribs was also about 6 inches. Its joints are
+remarkably short when compared with those of the neck. The tail is about
+20 inches long.
+
+The extreme length of the animal from the tip of the nose to the end of
+the tail may have been 3 feet 4 inches, supposing it to have walked on
+all fours in the manner of a Reptile or Mammal. This may have been a
+common position, but Dimorphodon may probably also have been a biped.
+Before 1875, when the first restoration appeared in the _Illustrated
+London News_, the legs had been regarded as too short to have supported
+the animal, standing upon its hind limbs. They are here seen to be well
+adapted for such a purpose. The upper leg bone is 3-1/4 inches long, the
+lower leg bone is 4-1/2 inches long, and the singularly strong instep
+bones are firmly packed together side by side as in a leaping or jumping
+Mammal, and measure 1-1/2 inches in length. Dimorphodon differs from
+several other Pterodactyles in having the hind limb provided with a
+fifth outermost short instep bone, to which two toe bones are attached.
+These bones are elongated in a way that may be compared, on a small
+scale, with the elongation of the wing finger in the fore limb. The
+digit was manifestly used in the same way as the wing finger, in partial
+support of a flying membrane, though its direction may have been upward
+and outward, rather than inward. There is no evidence of a pulley joint
+between the metatarsal and the adjacent phalange.
+
+The height of the Dimorphodon, standing on its hind legs in the position
+of a Bird, with the wings folded upon the body in the manner of a Bird,
+was about 20 inches. An ungainly, ill-balanced animal in aspect, but not
+more so than many big-headed birds, and probably capable of resting upon
+the instep bones as many birds do. The chief point of variation from the
+Pterodactyle wing is in the relative length of the metacarpus in
+Dimorphodon. It is shorter than the other bones in the wing, never
+exceeding 1-1/2 inches. The total length of all the arm bones down to
+the point where the metacarpus might have touched the ground, or where
+the wing finger is bent upon it, is about 9 inches, which gives a length
+of less than 6 inches below the upper arm bone. The four bones of the
+wing finger measure, from the point where the first bone bends upon the
+metacarpus, less than 18 inches. So that the wings could only have been
+carried in the manner of the wings of a Bat, folded at the side and
+directed obliquely over the back when the animal moved on all fours. Its
+body would appear to have been raised high above the ground, in a manner
+almost unparalleled in Reptiles, and comparable to Birds and Mammals.
+Dimorphodon is to be imagined in full flight, with the body extended
+like that of a Bird, when the wings would have had a spread from side to
+side of about 4 feet 4 inches. As in other animals of this group, the
+three claws on the front feet are larger than the similar four claws on
+the hind feet; as though the fingers might have functions in grasping
+prey, which were not shared by the toes.
+
+  [Illustration: FIG. 51.  DIMORPHODON MACRONYX WALKING AS A QUADRUPED
+  RESTORATION OF THE SKELETON]
+
+The restorations give faithful pictures of the skeleton, and the form of
+the body is built upon the indications of muscular structure seen in the
+bones.
+
+A second English Pterodactyle is found in the Upper Lias of Whitby. It
+is only known from an imperfect skull, published in 1888. It has the
+great advantage of preserving the bones in their natural relations to
+each other, and with a length of head probably similar to Dimorphodon
+shows that the depth at the back of the eye was much less; and the skull
+wants the arched contour of face seen in Dimorphodon. The head has the
+same four lateral vacuities, but the nostril is relatively small and
+elongated, extending partly above the oval antorbital opening, which was
+larger. There is thus a difference of proportion, but it is precisely
+such as might result from the species having the skull flatter. The head
+is easily distinguished by the small nostril, which is smaller than the
+orbit of the eye. The animal is referred to another genus. The quadrate
+bones which give attachment to the lower jaw send a process inward to
+meet the bones of the palate, which differ somewhat from the usual
+condition. Two bony rods extend from the quadrate bones backward and
+upward to the sphenoid, and two more slender bones extend from the
+quadrate bones forward, and converge in a #V#-shape, to define the
+division between the openings of the nostrils on the palate. The
+#V#-shaped bone in front is called the vomer, while the hinder part is
+called pterygoid. The bones that extend backward to the sphenoid are not
+easily identified. This animal is one of the most interesting of
+Pterodactyles from the very reptilian character exhibited in the back of
+the head, which appears to be different from other specimens, which are
+more like a bird in that region. Yet underneath this reptilian aspect,
+with the bony bar at the side of the temporal region of the head formed
+by the squamosal and quadrate bones, defining the two temporal vacuities
+as in Reptiles, a mould is preserved of the cavity once occupied by the
+brain, showing the chief details of structure of that organ, and proving
+that in so far as it departs from the brain of a Bird it appears to
+resemble the brain of a Mammal, and is unlike the brain of a Reptile.
+
+The Pterodactyles from the Lias of Germany are similar to the English
+types, in so far as they can be compared. In 1878 I had the opportunity
+of studying those which were preserved in the Castle at Banz, which
+Professor Andreas Wagner, in 1860, referred to the new genus
+Dorygnathus. The skull is unknown, but the lower jaw, 6-1/2 inches long,
+is less than 2-1/2 inches wide at the articulation with the quadrate
+bone in the skull. The depth of the lower jaw does not exceed 1/4 inch,
+so that it is in marked contrast to Buckland's Dimorphodon. The
+symphysis, which completely blends the rami of the jaw, is short. As far
+as it extends it contains large tearing teeth, followed by smaller teeth
+behind, like those of Dimorphodon. But this German fossil appears to
+differ from the English type in having the front of the lower jaw, for
+about 3/4 inch, compressed from side to side into a sharp blade or
+spear, more marked than in any other Pterodactyle, and directed _upward_
+instead of downward as in Dimorphodon. Nearly all the measurements in
+the skeleton are practically identical with those of the English
+Dimorphodon, and extend to the jaw, humerus, ulna and radius, wing
+metacarpal, first phalange of the wing finger. The principal bones of
+the hind limb appear to be a little shorter; but the scapula and
+coracoid are slightly larger. All these bones are so similar in form to
+Dimorphodon that they could not be separated from the Lyme Regis
+species, if they were found in the same locality.
+
+  [Illustration: FIG. 52.  DIMORPHODON MACRONYX WALKING AS A BIPED
+  _Based chiefly on remains in the British Museum_]
+
+  [Illustration: FIG. 53.  LOWER JAW OF DORYGNATHUS SEEN FROM BELOW
+
+  From the Lower Lias of Germany, showing the spear in front of the
+  tooth sockets]
+
+Just as the Upper Lias in England has yielded a second Pterodactyle, so
+the Upper Lias in Germany has yielded a skeleton, to which Felix
+Plieninger, in 1894, gave the name Campylognathus. It is an instructive
+skeleton, with the head much smaller than in Dimorphodon, being less
+than 6 inches long, but, unfortunately, broken and disturbed. A lower
+jaw gives the length 4-1/2 inches. Like the other Pterodactyles from
+the Lias, it has the extremity of the beak toothless, with larger teeth
+in the region of the symphysis in front and smaller teeth behind. The
+jaw is deeper than in the Banz specimen from the Lower Lias, but not so
+deep as in Dimorphodon. The teeth of the upper jaw vary in size, and
+there appears to be an exceptionally large tooth in the position of the
+Mammalian canine at the junction of the bones named maxillary and
+intermaxillary.
+
+The nasal opening is small and elongated, as in the English specimen
+from Whitby. As in that type there is little or no indication of the
+convex contour of the face seen in Dimorphodon.
+
+The neck does not appear to be preserved. In the back the vertebr� are
+about 3/10 inch long, so that twelve, which is the usual number, would
+only occupy a length of a little more than 3-1/2 inches. The tail is
+elongated like that of Dimorphodon, and bordered in the same way by
+ossified ligaments. There are thirty-five tail vertebr�. Those which
+immediately follow the pelvis are short, like the vertebr� of the back.
+But they soon elongate, and reach a maximum length of nearly 1-1/2
+inches at the eighth, and then gradually diminish till the last scarcely
+exceeds 1/8 inch in length. The length of the tail is about 22 inches;
+this appears to be an inch or two longer than in Dimorphodon. The
+longest rib measures 2-1/2 inches, and the shortest 2 inches. These ribs
+probably were connected with the sternum, which is imperfectly
+preserved.
+
+  [Illustration: FIG. 54.  DIMORPHODON MACRONYX
+  SHOWING THE MAXIMUM SPREAD OF THE WING MEMBRANES]
+
+The bones of the limbs have about the same length as those of
+Dimorphodon, so far as they can be compared, except that the ulna and
+radius are shorter. The wing metacarpal is of about the same length, but
+the first phalange of the wing finger measures 6-1/4 inches, the second
+is about 8-1/4 inches, the third 6-1/2 inches, and the fourth 4-3/4
+inches; so that the total length of the wing finger was about half an
+inch short of 2 feet. One character especially deserves attention in the
+apparent successive elongation of the first three phalanges in the wing
+finger in Dimorphodon. The third phalange is the longest in the only
+specimen in which the finger bones are all preserved. Usually the first
+phalange is much longer than the second, so that it is a further point
+of interest to find that this German type shares with Dimorphodon a
+character of the wing finger which distinguishes both from some members
+of the group by its short first phalange.
+
+  [Illustration: FIG. 55.  THE LEFT SIDE OF THE PELVIS OF DIMORPHODON
+  SHOWING THE TWO PREPUBIC BONES]
+
+The pelvis is exceptionally strong in Campylognathus, and although it is
+crushed the bones manifestly met at the base of the ischium, while the
+pubic bones were separated from each other in front. The bones of the
+hind limb are altogether shorter in the German fossil than in
+Dimorphodon, especially in the tibia; but the structure of the
+metatarsus is just the same, even to the short fifth metatarsal with its
+two digits, only those bones are extremely short, instead of being
+elongated as in Dimorphodon. It is therefore convenient, from the
+different proportions of the body, that Campylognathus may be separated
+from Dimorphodon; but so much as is preserved of the English specimen
+from the Upper Lias of Whitby rather favours the belief that our species
+should also be referred to Campylognathus, which had not been figured
+when the Whitby skull was referred to Scaphognathus by Mr. Newton. It
+may be doubtful whether there is sufficient evidence to establish the
+distinctness of the other German genus Dorygnathus, though it may be
+retained pending further knowledge.
+
+In these characters are grounds for placing the Lias Pterodactyles in a
+distinct family, the Dimorphodontid�, as was suggested in 1870. This
+evidence is found in the five metatarsal bones, of which four are in
+close contact, the middle two being slightly the longest, so as to
+present the general aspect of the corresponding bones in a Mammal rather
+than a Bird. Secondly, the very slender fibula, prolonged down the
+length of the shin bone, which ends in a rounded pulley like the
+corresponding bone of a Bird. Thirdly, the great elongation of the third
+wing phalange. Fourthly, the prolongation of the coracoid bone beyond
+the articulation for the humerus, as in a Bird. And the toothless,
+spear-shaped beak, and jaw with large teeth in front and small teeth
+behind, are also distinctive characters.
+
+
+
+
+CHAPTER XIV
+
+ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS
+
+
+RHAMPHOCEPHALUS
+
+THE Stonesfield Slate in England, which corresponds in age with the
+lower part of the Great or Bath Oolite, yields many evidences of
+terrestrial life--land plants, insects, and mammals--preserved in a
+marine deposit. A number of isolated bones have been found of
+Pterodactyles, some of them indicating animals of considerable size and
+strength. The nature of the limestone was unfavourable to the
+preservation of soft wing membranes, or even to the bones remaining in
+natural association. Very little is known of the head of
+Rhamphocephalus. One imperfect specimen shows a long temporal region
+which is wide, and a very narrow interspace between the orbits; with a
+long face, indicated by the extension of narrow nasal bones. The lower
+jaw has an edentulous beak or spear in front, which is compressed from
+side to side in the manner of the Liassic forms, but turned upward
+slightly, as in Dorygnathus or Campylognathus. Behind this extremity are
+sharp, tall teeth, few in number, which somewhat diminish in size as
+they extend backward, and do not suddenly change to smaller series, as
+in the Lias genera. A few small vertebr� have been found, indicating the
+neck and back. The sacrum consists of five vertebr�. One small example
+has a length of only an inch. It is a little narrower behind than in
+front, and would be consistent with the animal having had a long tail,
+which I believe to have been present, although I have not seen any
+caudal vertebr�. The early ribs are like the early ribs of a Crocodile
+or Bird in the well-marked double articulation. The later ribs appear to
+have but one head. #V#-shaped abdominal ribs are preserved. Much of the
+animal is unknown. The coracoid seems to have been directed forward,
+and, as in a bird, it is 2-1/2 inches long. The humerus is 3-1/2 inches
+long, and the fore-arm measured 6 inches, so that it was relatively
+longer than in Dimorphodon. The metacarpus is 1-3/4 inches long. The
+wing finger was exceptionally long and strong. Professor Huxley gave its
+length at 29 inches. My own studies lead to the conclusion that the
+first finger bone of the wing was the shorter, and that although they
+did not differ greatly in length, the second was probably the longest,
+as in Campylognathus.
+
+Professor Huxley makes the second and third phalanges 7-3/4 inches long,
+and the first only about 3/8 inch shorter, while the fourth phalange is
+6-1/2 inches. These measurements are based upon some specimens in the
+Oxford University Museum. There is only one first phalange which has a
+length of 7-3/4 inches. The others are between 5 and 6 inches, or but
+little exceed 4 inches; so that as all the fourth phalanges which are
+known have a length of 6-1/2 inches, it is possible that the normal
+length of the first phalange in the larger species was 5-1/2 inches. The
+largest of the phalanges which may be classed as second or third is
+8-1/2 inches, and that, I suppose, may have been associated with the
+7-3/4 inches first phalange. But the other bones which could have had
+this position all measure 5-1/2 and 7-3/4 inches. The three species
+indicated by finger bones may have had the measurements:--
+
+     Phalanges of the wing finger
+   ________________/\________________
+  |                                  |
+    I.        II.      III.      IV.
+  7-3/4     8-1/2      [7?]      6-1/2        }  length of each bone
+  5-1/2     7-3/4     5-1/2     [4-1/2?]      }       in inches.
+  4-1/2     ----      ----       ----         }
+
+The femur is represented by many examples--one 3-3/4 inches long, and
+others less than 3 inches long (2-9/10). In Campylognathus, which has so
+much in common with the jaw and the wing bones in size, the upper leg
+bone is 2-8/10 inches. Therefore if we assign the larger femur to the
+larger wing, the femur will be relatively longer in all species of
+Rhamphocephalus than in Campylognathus. Only one example of a tibia is
+preserved. It is 3-1/2 inches long, or only 1/10 inch shorter than the
+bone in Campylognathus, which has the femur 2-8/10 inches, so that I
+refer the tibia of Rhamphocephalus to the species which has the
+intermediate length of wing. These coincidences with Campylognathus
+establish a close affinity, and may raise the question whether the Upper
+Lias species may not be included in the Stonesfield Slate genus
+Rhamphocephalus.
+
+The late Professor Phillips, in his _Geology of Oxford_, attempted a
+restoration of the Stonesfield Ornithosaur, and produced a picturesque
+effect (p. 164); but no restoration is possible without such attention
+to the proportions of the bones as we have indicated.
+
+
+OXFORD CLAY
+
+A few bones of flying reptiles have been found in the Lower Oxford Clay
+near Peterborough, and others in the Upper Oxford Clay at St. Ives, in
+Huntingdonshire. A single tail vertebra from the Middle Oxford Clay,
+near Oxford, long since came under my own notice, and shows that these
+animals belong to a long-tailed type like Campylognathus. The cervical
+vertebr� are remarkable for being scarcely longer than the dorsal
+vertebr�; and the dorsal are at least half as long again as is usual,
+having rather the proportion of bones in the back of a crocodile.
+
+
+LITHOGRAPHIC SLATE
+
+Long-tailed Pterodactyles are beautifully preserved in the Lithographic
+Limestone of the south of Bavaria, at Solenhofen, and the quarries in
+its neighbourhood, often with the skeleton or a large part of it
+flattened out in the plane of bedding of the rock. Fine skeletons are
+preserved in the superb museum at Munich, at Heidelberg, Bonn, Haarlem,
+and London, and are all referred to the genus Rhamphorhynchus or to
+Scaphognathus. It is a type with powerfully developed wings and a long,
+stiff tail, very similar to that of Dimorphodon, so that some
+naturalists refer both to the same family. There is some resemblance.
+
+The type which is most like Dimorphodon is the celebrated fossil at
+Bonn, sometimes called _Pterodactylus crassirostris_, which in a
+restored form, with a short tail, has been reproduced in many
+text-books. No tail is preserved in the slab, and I ventured to give the
+animal a tail for the first time in a restoration (p. 163) published by
+the _Illustrated London News_ in 1875, which accompanied a report of a
+Royal Institution lecture. Afterwards, in 1882, Professor Zittel, of
+Munich, published the same conclusion. The reason for restoring the tail
+was that the animal had the head constructed in the same way as
+Pterodactyles with a long tail, and showed differences from types in
+which the tail is short; and there is no known short-tailed
+Pterodactyle, with wrist and hand bones, such as characterise this
+animal. The side of the face has a general resemblance to the
+Pterodactyles from the Lias, for although the framework is firmer, the
+four apertures in the head are similarly placed. The nostril is rather
+small and elongated, and ascends over the larger antorbital vacuity. The
+orbit for the eye is the largest opening in the head, so that these
+three apertures successively increase in size, and are followed by the
+vertically elongated post-orbital vacuity. The teeth are widely spaced
+apart, and those in the skull extend some distance backward to the end
+of the maxillary bone. There are few teeth in the lower jaw, and they
+correspond to the large anterior teeth of Dimorphodon, there being no
+teeth behind the nasal opening. The lower jaw is straight, and the
+extremities of the jaws met when the mouth was closed. The breast bone
+does not show the keel which is so remarkable in Rhamphorhynchus, which
+may be attributed to its under side being exposed, so as to exhibit the
+pneumatic foramina.
+
+The ribs have double heads, more like those of a Crocodile in the region
+of the back than is the case with the bird-like ribs from Stonesfield.
+The second joint in the wing finger may be longer than the first--a
+character which would tend to the association of this Pterodactyle with
+species from the Lias; a relation to which attention was first drawn by
+Mr. E. T. Newton, who described the Whitby skull.
+
+The Pterodactyles from the Solenhofen Slate which possess long tails
+have a series of characters which show affinity with the other
+long-tailed types. The jaws are much more slender. The orbit of the eye
+in Rhamphorhynchus is enormously large, and placed vertically above the
+articulation for the lower jaw. Immediately in front of the eye are two
+small and elongated openings, the hinder of which, known as the
+antorbital vacuity, is often slightly smaller than the nostril, which is
+placed in the middle length of the head, or a little further back,
+giving a long dagger-shaped jaw, which terminates in a toothless spear.
+The lower jaw has a corresponding sharp extremity. The teeth are
+directed forward in a way that is quite exceptional. Notwithstanding the
+massiveness and elongation of the neck vertebr�, which are nearly twice
+as long as those of the back, the neck is sometimes only about half the
+length of the skull.
+
+All these long-tailed species from the Lithographic Stone agree in
+having the sternum broad, with a long strong keel, extending far
+forward. The coracoid bones extend outward like those of a Crocodile, so
+as to widen the chest cavity instead of being carried forward as the
+bones are in Birds. These bones in this animal were attached to the
+anterior extremity of the sternum, so that the keel extended in advance
+of the articulation as in other Pterodactyles. The breadth of the
+sternum shows that, as in Mammals, the fore part of the body must have
+been fully twice the width of the region of the hip-girdle, where the
+slenderer hind limbs were attached. The length of the fore limb was
+enormous, for although the head suggests an immense length relatively
+to the body, nearly equal to neck and back together, the head is not
+more than a third of the length of the wing bones. The wing bones are
+remarkable for the short powerful humerus with an expanded radial crest,
+which is fully equal in width to half the length of the bone. Another
+character is the extreme shortness of the metacarpus, usually associated
+with immense strength of the wing metacarpal bone.
+
+The hind limbs are relatively small and relatively short. The femur is
+usually shorter than the humerus, and the tibia is much shorter than the
+ulna. The bones of the instep, instead of being held together firmly as
+in the Lias genera, diverge from each other, widening out, though it
+often happens that four of the five metatarsals differ but little in
+length. The fifth digit is always shorter.
+
+The hip-girdle of bones differs chiefly from other types in the way in
+which those bones, which have sometimes been likened to the marsupial
+bones, are conditioned. They may be a pair of triangular bones which
+meet in the middle line, so that there is an outer angle like the arm of
+a capital Y. Sometimes these triangular bones are blended into a curved,
+bow-shaped arch, which in several specimens appears to extend forward
+from near the place of articulation of the femur. This is seen in fossil
+skeletons at Heidelberg and Munich. It is possible that this position is
+an accident of preservation, and that the prepubic bones are really
+attached to the lower border of the pubic bones.
+
+Immense as the length of the tail appears to be, exceeding the skull and
+remainder of the vertebral column, it falls far short of the combined
+length of the phalanges of the wing finger. The power of flight was
+manifestly greater in Rhamphorhynchus than in other members of the
+group, and all the modifications of the skeleton tend towards adaptation
+of the animals for flying. The most remarkable modification of structure
+at the extremity of the tail was made known by Professor Marsh in a
+vertical, leaf-like expansion in this genus, which had not previously
+been observed (p. 161). The vertebr� go on steadily diminishing in
+length in the usual way, and then the ossified structures which bordered
+the tail bones and run parallel with the vertebr� in all the
+Rhamphorhynchus family, suddenly diverge downward and upward at right
+angles to the vertebr�, forming a vertical crest above and a
+corresponding keel below; and between these structures, which are
+identified with the neural spines and chevron bones of ordinary
+vertebr�, the membrane extends, giving the extremity of the tail a
+rudder-like feature, which, from knowledge of the construction of the
+tail of a child's kite, may well be thought to have had influence in
+directing and steadying the animal's movements. There are many minor
+features in the shoulder-girdle, which show that the coracoid, for
+example, was becoming unlike that bone in the Lias, though it still
+continues to have a bony union with the elongated shoulder-blade of the
+back.
+
+  [Illustration: FIG. 56.  RESTORATION OF THE SKELETON OF
+  _RHAMPHORHYNCHUS PHYLLURUS_
+
+  From the Solenhofen Slate, partly based upon the skeleton
+  with the wing membranes preserved]
+
+  [Illustration: FIG. 57.  RESTORATION OF THE SKELETON OF _SCAPHOGNATHUS
+  CRASSIROSTRIS_
+
+  Published in the _Illustrated London News_ in 1875. In which a tail is
+  shown on the evidence of the structure of the head and hand]
+
+  [Illustration: FIG. 58.  SIX RESTORATIONS
+
+    1. Ramphocephalus. Stonesfield Slate. John Phillips, 1871
+    2. Rhamphorhynchus. O. C. Marsh, 1882
+    3. Rhamphorhynchus. V. Zittel, 1882
+    4. Ornithostoma. Williston, 1897
+    5. Dimorphodon. Buckland, 1836. Tail then unknown
+    6. Ornithocheirus. H. G. Seeley, 1865]
+
+The great German delineator of these animals, Von Meyer, admitted six
+different species. Mr. Newton and Mr. Lydekker diminish the number to
+four. It is not easy to determine these differences, or to say how far
+the differences observed in the bones characterise species or genera. It
+is certain that there is one remarkable difference from other and older
+Pterodactyles, in that the last or fourth bone in the wing finger is
+usually slightly longer than the third bone, which precedes it. There is
+a certain variability in the specimens which makes discussion of their
+characters difficult, and has led to some forms being regarded as
+varieties, while others, of which less material is available, are
+classed as species. I am disposed to say that some of the confusion may
+have resulted from specimens being wrongly named. Thus, there is a
+Rhamphorhynchus called curtimanus, or the form with the short hand. It
+is represented by two types. One of these appears to have the humerus
+short, the ulna and radius long, and the finger bones long; the other
+has the humerus longer, the ulna much shorter, and the finger bones
+shorter. They are clearly different species, but the second variety
+agrees in almost every detail with a species named hirundinaceus, the
+swallow-like Rhamphorhynchus. This identification shows, not that the
+latter is a bad species, but that curtimanus is a distinct species which
+had sometimes been confounded with the other. While most of these
+specimens show a small but steady decrease in the length of the several
+wing finger bones, the species called Gemmingi has the first three bones
+absolutely equal and shorter than in the species curtimanus, longimanus,
+or hirundinaceus. In the same way, on the evidence of facts, I find
+myself unable to join in discarding Professor Marsh's species phyllurus,
+on account of the different proportions of its limb bones. The humerus,
+metacarpus, and third phalange of the wing finger in _Rhamphorhynchus
+phyllurus_ are exceptionally short as compared with other species.
+Everyone agrees that the species called longicaudus is a distinct one,
+so that it is chiefly in slight differences in the proportions of
+constituent parts of the skeleton that the types of the Rhamphorhynchus
+are distinguished from each other. I cannot quite concur with either
+Professor Zittel (Fig. 58, 3) or Professor Marsh (Fig. 58, 2) in the
+expansion which they give to the wing membrane in their restorations;
+for although Professor Zittel represents the tail as free from the hind
+legs, while Professor Marsh connects them together, they both concur in
+carrying the wing membrane from the tip of the wing finger down to the
+extremity of the ankle joint. I should have preferred to carry it no
+further down the body than the lower part of the back, there being no
+fossil evidence in favour of this extension so far as specimens have
+been described. Neither the membranous wings figured by Zittel nor by
+Marsh would warrant so much body membrane as the Rhamphorhynchus has
+been credited with. I have based my restoration (p. 161) of the skeleton
+chiefly on _Rhamphorhynchus phyllurus._
+
+
+THE SHORT-TAILED TYPES
+
+The Pterodactylia are less variable; and the variation among the species
+is chiefly confined to relative length of the head, length of the neck,
+and the height of the body above the ground. The tail is always so short
+as to be inappreciable. Many of the specimens are fragmentary, and the
+characters of the group are not easily determined without careful
+comparisons and measurements. The bones of the fore limb and wing
+finger are less stout than in the Rhamphorhynchus type, while the femur
+is generally a little longer than the humerus, and the wing finger is
+short in comparison with its condition in Rhamphorhynchus. These
+short-tailed Pterodactyles give the impression of being active little
+animals, having very much the aspect of birds, upon four legs or two.
+The neck is about as long as the lower jaw, the antorbital vacuity in
+the head is imperfectly separated from the much larger nasal opening,
+the orbit of the eye is large and far back, the teeth are entirely in
+front of the nasal aperture, and the post-orbital vacuity is minute and
+inconspicuous. The sternum is much wider than long, and no specimens
+give evidence of a manubrium. The finger bones progressively decrease in
+length. The prepubic bones have a partially expanded fan-like form, and
+never show the triradiate shape, and are never anchylosed. About fifteen
+different kinds of Pterodactyles have been described from the Solenhofen
+Slate, mostly referred to the genus Pterodactylus, which comprises forms
+with a large head and long snout. Some have been placed in a genus
+(Ornithocephalus, or Ptenodracon) in which the head is relatively short.
+The majority of the species are relatively small. The skull in
+_Ornithocephalus brevirostris_ is only 1 inch long, and the animal could
+not have stood more than 1-1/2 inches to its back standing on all fours,
+and but little over 2-1/2 inches standing as a biped, on the hind limbs.
+
+A restoration of the species called _Pterodactylus scolopaciceps_,
+published in 1875 in the _Illustrated London News_ in the position of a
+quadruped, shows an animal a little larger, with a body 2-1/2 inches
+high and 6 to 7 inches long, with the wing finger 4-1/2 inches long.
+Larger animals occur in the same deposit, and in one named
+_Pterodactylus grandis_ the leg bones are a foot long; and such an
+animal may have been nearly a foot in height to its back, standing as a
+quadruped, though most of these animals had the neck flexible and
+capable of being raised like the neck of a Goose or a Deer (p. 30), and
+bent down like a Duck's when feeding.
+
+  [Illustration: FIG. 59.  RESTORATION OF THE SKELETON OF _PTENODRACON
+  BREVIROSTRIS_
+
+  From the Solenhofen Slate. The fourth joint of the wing finger appears
+  to be lost and has not been restored in the figure. (Natural size)]
+
+The type of the genus Pterodactylus is the form originally described by
+Cuvier as_ Pterodactylus longirostris_ (p. 28). It is also known as _P.
+antiquus_, that name having been given by a German naturalist after
+Cuvier had invented the genus, and before he had named the species.
+There are some remarkable features in which Cuvier's animal is distinct
+from others which have been referred to the same genus. Thus the head is
+4-1/2 inches long, while the entire length of the backbone to the
+extremity of the tail is only 6-1/2 inches, and one vertebra in the neck
+is at least as long as six in the back, so that the animal has the
+greater part of its length in the head and neck, although the neck
+includes so few vertebr�. Nearly all the teeth--which are few in number,
+short and broad, not exceeding a dozen in either jaw--are limited to the
+front part of the beak, and do not extend anywhere near the nasal
+vacuity. This is not the case with all.
+
+In the species named _P. Kochi_, which I have regarded as the type of a
+distinct genus, there are large teeth in the front of the jaw
+corresponding to those of Pterodactylus, and behind these a smaller
+series of teeth extending back under the nostril, which approaches close
+to the orbit of the eye, without any indication of a separate antorbital
+vacuity. On those characters the genus Diopecephalus was defined. It is
+closely allied to Pterodactylus; both agree in having the ilium
+prolonged forward more than twice as far as it is carried backward, the
+anterior process covering about half a dozen vertebr�, as in
+_Pterodactylus longirostris_. A great many different types have been
+referred to _Pterodactylus Kochi_, and it is probable that they may
+eventually be distinguished from each other. The species in which the
+upper borders of the orbits approximate could be separated from those in
+which the frontal interspace is wider.
+
+  [Illustration: FIG. 60.  CYCNORHAMPHUS SUEVICUS FROM THE SOLENHOFEN
+  SLATE SHOWING THE SCATTERED POSITION OF THE BONES
+
+  _Original in the Museum at T�bingen_]
+
+  [Illustration: FIG. 61.  CYCNORHAMPHUS SUEVICUS
+  RESTORATION SHOWING THE FORM OF THE BODY AND THE WING MEMBRANES]
+
+It is a remarkable feature in these animals that the middle bones of the
+foot, termed instep bones or metatarsals, are usually close together, so
+that the toes diverge from a narrow breadth, as in _P. longirostris_,
+_P. Kochi_, and other forms; but there also appear to be splay-footed
+groups of Pterodactyles like the species which have been named _P.
+elegans_ and _P. micronyx_, in which the metatarsus widens out so that
+the bones of the toes do not diverge, and that condition characterises
+the Ptenodracon (_Pterodactylus brevirostris_), to which genus these
+species may possibly be referred. Nearly all who have studied these
+animals regard the singularly short-nosed species _P. brevirostris_ as
+forming a separate genus. For that genus S�mmerring's descriptive name
+Ornithocephalus, which he used for Pterodactyles generally, might
+perhaps have been retained. But the name Ptenodracon, suggested by Mr.
+Lydekker, has been used for these types.
+
+  [Illustration: FIG. 62.  _CYCNORHAMPHUS SUEVICUS_
+
+  Skeleton restored from the bones in Fig. 60]
+
+  [Illustration: FIG. 63.  RESTORATION OF SKELETON CYCNORHAMPHUS FRAASI
+  SHOWING THE LIMBS ON THE RIGHT SIDE
+
+  _From a specimen in the Museum at Stuttgart_]
+
+  [Illustration: FIG. 64.  CYCNORHAMPHUS FRAASI
+  RESTORATION OF THE FORM OF THE BODY]
+
+Some of the largest specimens preserved at Stuttgart and T�bingen have
+been named _Pterodactylus suevicus_ and _P. Fraasii_. They do not
+approach the species _P. grandis_ in size, so far as can be judged from
+the fragmentary remains figured by Von Meyer; for what appears to be the
+third phalange of the wing finger is 7-1/2 inches long, while in these
+species it is less than half that length, indicating an enormous
+development of wing, relatively to the length of the hind limb, which
+would probably refer the species to another genus. _Pterodactylus
+suevicus_ differs from the typical Pterodactyles in having a rounded,
+flattened under surface to the lower jaw, instead of the common
+condition of a sharp keel in the region of the symphysis. The beak also
+seems flattened and swan-like, and the teeth are limited to the front of
+the jaw. There appear to be some indications of small nostrils, which
+look upward like the nostrils of Rhamphorhynchus, but this may be a
+deceptive appearance, and the nostrils are large lateral vacuities,
+which are in the position of antorbital vacuities, so that there would
+appear to be only two vacuities in the side of the head in these
+animals. The distinctive character of the skeleton in this genus is
+found in the extraordinary length of the metacarpus and in the complete
+ossification of the smaller metacarpal bones throughout their length.
+The metacarpal bones are much longer than the bones of the fore-arm, and
+about twice the length of the humerus. The first wing phalange is much
+longer than the others, which successively and rapidly diminish in
+length, so that the third is half the length of the first. There are
+differences in the pelvis; for the anterior process of the ilium is very
+short, in comparison with its length in the genus Pterodactylus. And the
+long stalk of the prepubic bone with its great hammer-headed expansion
+transversely in front gives those bones a character unlike other genera,
+so that Cycnorhamphus ranks as a good genus, easily distinguished from
+Cuvier's type, in which the four bones of the wing are more equal in
+length, and the last is more than half the length of the first; while
+the metacarpus in that genus is only a little longer than the humerus,
+and much shorter than the ulna. The _Pterodactylus suevicus_ has the
+neck vertebr� flat on the under side, and relatively short as compared
+with the more slender and narrower vertebr� of _P. Fraasii_.
+
+
+
+
+CHAPTER XV
+
+ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS
+
+
+When staying at Swanage, in Dorsetshire, many years ago, I had the rare
+good fortune to obtain from the Purbeck Beds the jaw of a Pterodactyle,
+which had much in common in plan with the _Cycnorhamphus Fraasii_ from
+the Lithographic Slate, which is preserved at Stuttgart. The
+tooth-bearing part of this lower jaw is 8 inches long as preserved,
+extending back 3 inches beyond the symphysis portion in which the two
+sides are blended together. It is different from Professor Fraas's
+specimen in having the teeth carried much further back, and in the
+animal being nearly twice as large. This fragment of the jaw is little
+more than 1 foot long, which is probably less than half its original
+length. A vertebra nearly 5 inches long, which is more than twice the
+length of the longest neck bones in the Stuttgart fossil, is the only
+indication of the vertebral column. Professor Owen described a wing
+finger bone from these Purbeck Beds, which is nearly 1 foot long. He
+terms it the second of the finger. It may be the third, and on the
+hypothesis that the animal had the proportions of the Solenhofen fossil
+just referred to, the first wing finger bone of the English Purbeck
+Pterodactyle would have exceeded 2 feet in length, and would give a
+length for the wing finger of about 5 feet 3 inches. For this animal the
+name Doratorhynchus was suggested, but at present I am unable to
+distinguish it satisfactorily from Cycnorhamphus, which it resembles in
+the forms both of the neck bones and of the jaw. Very small
+Pterodactyles are also found in the English Purbeck strata, but the
+remains are few, and scattered, like these larger bones.
+
+  [Illustration: FIG. 65.  THE LONGEST KNOWN NECK VERTEBRA
+
+  From the Purbeck Beds of Swanage. (Half natural size)]
+
+
+ORNITHODESMUS LATIDENS
+
+  [Illustration: FIG. 66.  CERVICAL VERTEBRA OF ORNITHODESMUS
+
+  From the Wealden Beds of the Isle of Wight]
+
+The Wealden strata being shallow, fresh-water deposits might have been
+expected to supply better knowledge of Pterodactyles than has hitherto
+been available. Jaws of Ornithocheirus sagittirostris have been found
+in the beds at Hastings, and in other parts of Sussex. Some fragments
+are as large as anything known. The best-preserved remains have come
+from the Isle of Wight, and were rewards to the enthusiastic search of
+the Rev. W. Fox, of Brixton. In the principal specimen the teeth were
+short and wide, the head large and deep with large vacuities, but the
+small brain case of that skull is bird-like. The neck bones are 2-1/2
+inches long. In the upper part of the back the bones are united together
+by anchylosis, so that they form a structure in the back like a sacrum,
+which does not give attachment to the scapula, as in some Pterodactyles
+from the Chalk, but the bones are simply blended, as in the
+frigate-bird, allied to Pelicans and Cormorants. And then after a few
+free vertebr� in the lower part of the back, succeeds the long sacrum,
+formed in the usual way, of many vertebr�. I described a sacrum of this
+type from the Wealden Beds, under the name _Ornithodesmus_, referable to
+another species, which in many respects was so like the sacrum of a Bird
+that I could not at the time separate it from the bird type. This genus
+has a sternum with a strong deep keel, and the articulation for the
+coracoid bones placed at the back of the keel in the usual way, but with
+a relation to each other seen in no genus hitherto known, for the
+articular surfaces are wedge-shaped instead of being ovate; and instead
+of being side by side, they obliquely overlap, practically as in wading
+birds like the Heron. I have never seen any Pterodactyle teeth so
+flattened and shaped like the end of a lancet; and from this character
+the form was known between Mr. Fox and his friends as "latidens." The
+name Ornithodesmus is as descriptive of the sternum as of the vertebral
+column. The wing bones, as far as they are preserved, have the
+relatively great strength in the fore limb which is found in many of the
+Pterodactyles of the Cretaceous period, and are quite as large as the
+largest from the Cambridge Greensand. In the Sussex species named _P.
+sagittirostris_ the lower jaw articulation was inches wide.
+
+
+  [Illustration: FIG. 67.  STERNUM OF _ORNITHODESMUS_
+
+  Showing the overlapping facets for the coracoid bones (shaded) behind
+  the median keel]
+
+  [Illustration: FIG. 68.  FRONT OF THE KEEL OF THE STERNUM OF
+  _ORNITHODESMUS LATIDENS_
+
+  Showing also the articulation for the coracoid bone]
+
+A few Pterodactyles' bones have been discovered in the Neocomian sands
+of England and Germany, and other larger bones occur in the Gault of
+Folkestone and the north of France; but never in such association as to
+throw light on the aspect of the skeleton.
+
+
+ORNITHOCHEIRUS
+
+Within my own memory Pterodactyle remains were equally rare from the
+Cambridge Greensand. The late Professor Owen in one of his public
+lectures produced the first few fragments received from Cambridge, and
+with a knowledge which in its scientific method seemed to border on the
+power of creation, produced again the missing parts, so that the bones
+told their story, which the work of waves and mineral changes in the
+rock had partly obliterated. Subsequently good fortune gave me the
+opportunity during ten years to help my University in the acquisition
+and arrangement of the finest collection of remains of these animals in
+Europe. Out of an area of a few acres, during a year or two, came the
+thousand bones of Ornithosaurs, mostly associated sets of remains, each
+a part of a separate skeleton, described in my published catalogues, as
+well as the best of those at York and in the British Museum and other
+collections in London.
+
+The deposit which yields them, named Cambridge Greensand, may or may not
+represent a long period of time in its single foot of thickness; but the
+abundance of fossils, obtained whenever the workmen were adequately
+remunerated for preserving them, would suggest that the Pterodactyles
+might have lived like sea-birds or in colonies like the Penguins, if it
+were not that the number of examples of each species found is always
+small, and the many variations of structure suggested rather that the
+individuals represent the life of many lands. The collections of remains
+are mostly from villages in the immediate vicinity of Cambridge, such as
+Chesterton, Huntingdon Road, Coldham Common, Haslingfield, Barton,
+Shillington, Ditton, Granchester, Harston, Barrington, stretching south
+to Ashwell in Bedfordshire on the one hand, as well as further north by
+Horningsea into the fens. Each appears to be the associated bones of a
+single individual. The remains mostly belong to comparatively large
+animals. Some were small, though none have been found so diminutive as
+the smallest from the Solenhofen Slate. The largest specimens with long
+jaws appear to have had the head measuring not more than eighteen inches
+in length, which is less than half the size of the great toothless
+Pterodactyles from Kansas.
+
+  [Illustration: FIG. 69.  RESTORATION OF THE SKULL OF ORNITHOCHEIRUS
+
+  The parts left white are in the Geological Museum at Cambridge. The
+  shaded parts have not been found. The two holes are the eye and the
+  nostril (From the Cambridge Greensand)]
+
+The Cambridge specimens manifestly belong to at least three genera.
+Something may be said of the characters of the large animals which are
+included in the genus Ornithocheirus. These fossils have many points of
+structure in common with the great American toothless forms which are of
+similar geological age. The skull is remarkable for having the back of
+the head prolonged in a compressed median crest, which rose above the
+brain case, and extended upward and over the neck vertebr�, so as to
+indicate a muscular power not otherwise shown in the group. For about
+three inches behind the brain this wedge of bone rested on the vertebr�,
+and probably overlapped the first three neural arches in the neck.
+
+Another feature of some interest is the expansion of the bone which
+comes below the eye. In Birds this malar or cheek bone is a slender rod,
+but in these Pterodactyles it is a vertical plate, which is blended with
+the bone named the quadrate bone, which makes the articulation with the
+lower jaw in all oviparous animals.
+
+The beak varies greatly in length and in form, though it is never quite
+so pointed as in the American genus, for there is always a little
+truncation in front, when teeth are seen projecting forward from a
+position somewhat above the palate; the snout is often massive and
+sometimes club-shaped. Except for these variations of shape in the
+compressed snout, which is characterised by a ridge in the middle of the
+palate, and a corresponding groove in the lower jaw, and the teeth,
+there is little to distinguish what is known of the skull in its largest
+English Greensand fossils from the skull remains which abound in the
+Chalk of Kansas.
+
+This English genus Ornithocheirus, represented by a great number of
+species, had the neural arch of the neck bones expanded transversely
+over the body of the vertebra in a way that characterises many birds
+with powerful necks, and is seen in a few Pterodactyles from Solenhofen.
+
+It is difficult to resist the conclusion that the neck vertebr� were
+not usually more than twice to three times as long as those of the back,
+and it would appear that the caudal vertebr� in the English Cretaceous
+types were comparatively large, and about twice as long as the dorsal
+vertebr�. Unless there has been a singular succession of accidents in
+the association of these vertebr� with the other remains, Ornithocheirus
+had a tail of moderate length, formed of a few vertebr� as long as those
+of the neck, though more slender, quite unlike the tail in either the
+long-tailed or short-tailed groups of Solenhofen Pterodactyles, and
+longer than in the toothless Pterodactyles of America.
+
+  [Illustration: FIG. 70.  CERVICAL VERTEBRA, ORNITHOCHEIRUS
+
+  Under side, half natural size. (Cambridge Greensand)]
+
+The singular articulation for the humerus at the truncated extremity of
+the coracoid bone is a character of this group, as is the articulation
+of the scapul� with the neural arches of the dorsal vertebr�, at right
+angles to them (p. 115), instead of running over the ribs as in Birds
+and as in other Pterodactyles.
+
+The smaller Pterodactyles have their jaws less compressed from side to
+side. The upper arm bone, the humerus, instead of being truncated at its
+lower end as in Ornithocheirus, is divided into two or three rounded
+articular surfaces. That for the radius, the bone which carries the
+wrist, is a distinct and oblique rounded facet, while the ulna has a
+rounded and pulley-like articulation on which the hand may rotate. These
+differences are probably associated with an absence of the remarkable
+mode of union of the scapul� with the dorsal vertebr�. But I have
+hesitated to give different names to these smaller genera because no
+example of scapula has come under my notice which is not truncated at
+the free end. I do not think this European type can be the Nyctodactylus
+of Professor Marsh, in which sutures appear to be persistent between the
+bodies of the vertebr� and their arches, because no examples have been
+found at Cambridge with the neural arches separated, although the
+scapula is frequently separated from the coracoid in large animals.
+
+  [Illustration: FIG. 71.  UPPER AND LOWER JAWS OF AN ENGLISH
+  PTERODACTYLE FROM THE CHALK, AS PRESERVED]
+
+
+ORNITHOSTOMA
+
+  [Illustration: FIG. 72.  THE PALATE OF THE ENGLISH TOOTHLESS
+  PTERODACTYLE, ORNITHOSTOMA]
+
+  [Illustration: FIG. 73.  TYPES OF THE AMERICAN TOOTHLESS PTERODACTYLE,
+  ORNITHOSTOMA
+
+  Named by Marsh, Pteranodon]
+
+The most interesting of all the English Pterodactyle remains is the
+small fragment of jaw figured by Sir Richard Owen in 1859, which is a
+little more than two inches long and an inch wide, distinguished by a
+concave palate with smooth rounded margins to the jaws and a rounded
+ridge to the beak. It is the only satisfactory fragment of the animal
+which has been figured, and indicates a genus of toothless
+Pterodactyles, for which the name Ornithostoma was first used in 1871.
+After some years Professor Marsh found toothless Pterodactyles in
+Kansas, and indicated several species. There are remains to the number
+of six hundred specimens of these American animals in the Yale Museum
+alone; but very little was known of them till Professor Williston, of
+Lawrence, in Kansas, described the specimens from the Kansas University
+Museum, when it became evident that the bones of the skeleton are mostly
+formed on the same plan as those of the Cambridge Greensand genus,
+Ornithocheirus. They are not quite identical. Professor Williston adopts
+for them the name Ornithostoma, in preference to Pteranodon which Marsh
+had suggested. Both animals have the dagger-shaped form of jaw, with
+corresponding height and breadth of the palate. The same flattened sides
+to the snout, converging upwards to a rounded ridge, the same compressed
+rounded margin to the jaw, which represents the border in which teeth
+are usually implanted, and in both the palate has the same smooth
+character forming a single wide concave channel. Years previously I had
+the pleasure of showing to Professor Marsh the remarkable characters of
+the jaw, shoulder-girdle bones, and scapul� in the Greensand
+Pterodactyles while the American fossils were still undiscovered. I
+subsequently made the restoration of the shoulder-girdle (p. 115).
+Professor Williston states to me that the shoulder-girdle bones in
+American examples of Ornithostoma have a close resemblance to those of
+Ornithocheirus figured in 1891, as is evident from remains now shown in
+the British Museum. It appears that the Kansas bones are almost
+invariably crushed flat, so that their articular ends are distorted. The
+neck vertebr� are relatively stout as in Ornithocheirus. The hip-girdle
+of the American Ornithostoma can be closely paralleled in some English
+specimens of Ornithocheirus, though each prepubic bone is triangular in
+the American fossils as in _P. rhamphastinus_. They are united into a
+transverse bar as in Rhamphorhynchus, unknown in the English fossils.
+The femur has the same shape as in Ornithocheirus; and the long tibia
+terminates in a pulley. There is no fibula. The sternum in both has a
+manubrium, or thick keel mass, prolonged in front of its articular
+facets for the coracoid bones, which are well separated from each other.
+Four ribs articulate with its straight sides. The animal has four toes
+and the fifth is rudimentary; there are no claws to the first and
+second.
+
+  [Illustration: FIG. 74.  RESTORATION OF THE SKELETON OF _ORNITHOSTOMA
+  INGENS_ (MARSH)
+
+  From the Niobrara Cretaceous of Western Kansas. Made by Professor
+  Williston. The original has a spread of wing of about 19 feet 4
+  inches. Fragments of larger individuals are preserved at Munich]
+
+In the restoration which Professor Williston has made the wing
+metacarpal is long, and in the shortest specimen measures 1 foot 7
+inches, and in the longest 1 foot 8 inches. This is exactly equal to the
+length of the first phalange of the wing finger. The second wing finger
+bone is 3 inches shorter, the third is little more than half the length
+of the first, while the fourth is only 6-3/4 inches long, showing a
+rapid shortening of the bones, a condition which may have characterised
+all the Cretaceous Pterodactyles. The short humerus, about 1 foot long,
+and the fore-arm, which is scarcely longer, are also characteristic
+proportions of Ornithostoma or Pteranodon, as known from the American
+specimens. Professor Williston gives no details of the remarkable tail,
+beyond saying that the tail is small and short, and that the vertebr�
+are flat at the ends, without transverse processes. In the restoration
+the tail is shorter than in the short-tailed species from the
+Lithographic Slate, and unlike the tail in Ornithocheirus.
+
+
+This is the succession of Pterodactyles in geological time. Their
+history is like that of the human race. In the most ancient nations
+man's life comes upon us already fully organised. The Pterodactyles
+begin, so far as isolated bones are concerned, in the Rh�tic strata;
+perhaps in the Muschelkalk or middle division of the Trias. And from the
+beginning of the Secondary time they live on with but little diversity
+in important and characteristic structures, and so far as habit goes,
+the great Pterodactyles of the Upper Chalk of England cannot be said to
+be more highly organised than the earlier stiff-tailed genera of the
+Lias or the Oolites. There is nothing like evolution. No modification
+such as that which derives the one-toed horse or the two-toed ox from
+ancestors with a larger number of digits. On the other hand, there is
+little, if any, evidence of degeneration. The later Pterodactyles do not
+appear to have lost much, although the tail in some of the Solenhofen
+genera may be degenerate when compared with the long tail of
+Dimorphodon; but the short-tailed types are found side by side with the
+long-tailed Rhamphorhynchus. The absence of teeth may be regarded as
+degeneration, for they have presumably become lost, in the same way that
+Birds now existing have lost the teeth which characterised the fossil
+birds--Ichthyornis of the American Greensand, and Arch�opteryx of the
+Upper Oolites of Bavaria. But just as some of the earlier Pterodactyles
+have no teeth at the extremity of the jaw, such as Dorygnathus and
+Rhamphorhynchus, so the loss of teeth may have extended backward till
+the jaws became toothless. The specimens hitherto known give no evidence
+of such a change being in progress. But just as the division of Mammals
+termed Edentata usually wants only the teeth which characterise the
+front of the jaw, yet others, like the Great Ant-eater of South America
+named Myrmecophaga, have the jaws as free from teeth as the toothless
+Pterodactyles or living Birds, and show that in that order the teeth
+have no value in separating these animals into subordinate groups any
+more than they have among the Monotremata, where one type has teeth and
+the other is toothless.
+
+The following table gives a summary of the Geological History and
+succession in the Secondary Rocks of the principal genera of Flying
+Reptiles.
+
+  -----------------------+----------------------------------------------
+                         |             NAMES OF THE GENERA.
+  GEOLOGICAL FORMATIONS. +-----------------------+----------------------
+                         | British and European. | North American.
+  -----------------------+-----------------------+----------------------
+  Upper Chalk            |                       |} Ornithostoma
+                         |                       |}     (_Pteranodon_)
+  Lower Chalk            |} Ornithocheirus       |} Nyctodactylus
+  Upper Greensand        |}   |  Ornithostoma    |
+  Gault                  |    |                  |
+  -----------------------+    |                  |
+  Lower Greensand        |    |                  |
+  Wealden                | Ornithodesmus         |
+  Purbeck                | Doratorhynchus        |
+  -----------------------+                       |
+  Portland               |{ Pterodactylus        |
+                         |{ Ptenodracon          |
+  Kimeridge Clay and     |{ Cycnorhamphus        |
+    Solenhofen Slate     |{ Diopecephalus        |
+                         |{ Rhamphorhynchus      |
+  Coralline Oolite       |{ Scaphognathus        |
+                         |                       |
+  Oxford Clay            |                       |
+  -----------------------+                       |
+  Great Oolite and       |                       |
+    Stonesfield Slate    | Rhamphocephalus       |
+                         |                       |
+  Inferior Oolite        |                       |
+  -----------------------+                       |
+  Upper Lias             |{ Campylognathus       |
+                         |{ Dorygnathus          |
+  Lower Lias             |  Dimorphodon          |
+  -----------------------+                       |
+  Rh�tic                 |  bones                |
+                         |                       |
+  Muschelkalk            |  ? bones              |
+  -----------------------+-----------------------+----------------------
+
+
+
+
+CHAPTER XVI
+
+CLASSIFICATION OF THE ORNITHOSAURIA
+
+
+When an attempt is made to determine the place in nature of an extinct
+group of animals and the relation to each other of the different types
+included within its limits, so as to express those facts in a
+classification, attention is directed in the first place to characters
+which are constant, and persist through the whole of its constituent
+genera. We endeavour to find the structural parts of the skeleton which
+are not affected by variation in the dentition, or the proportions of
+the extremities, or length of the tail, which may define families or
+genera, or species.
+
+It has already been shown that while in many ways the Ornithosaurian
+animals are like Birds, they have also important resemblances to
+Reptiles. They are often named Pterosauria. The wing finger gives a
+distinctive character which is found in neither one class of existing
+animals nor the other, and is common to all the Pterodactyles at present
+known. They have been named Ornithosauria as a distinct minor division
+of back-boned animals, which may be regarded as neither Reptiles nor
+Birds in the sense in which those terms are used to define a Lizard or
+Ostrich among animals which still exist. It is not so much that they
+mark a transition from Reptile to Bird, as that they are a group which
+is parallel to Birds, and more manifestly holds an intermediate place
+than Birds do between Reptiles and Mammals. In plan of structure Bird
+and Reptile have more in common than was at one time suspected. The late
+Professor Huxley went so far as to generalise on those coincidences in
+parts of the skeleton, and united Birds and Reptiles into one group,
+which he named Sauropsida, to express the coincidences of structure
+between the Lizard and the Bird tribes. The idea is of more value than
+the term in which it is expressed, because Reptiles are not, as we have
+seen, a group of animals which can be defined by any set of characters
+as comprehensive as those which express the distinctive features of
+Birds. From the anatomist's point of view Birds are a smaller group, and
+while some Reptiles have affinity with them, it is rather the extinct
+than the living groups which indicate that relation. Other Reptiles have
+affinities of a more marked kind with Mammals, and there are points in
+the Ornithosaurian skeleton which are distinctly Mammalian. So that when
+the Monotreme Mammals are united with South African reptiles known as
+Theriodontia, which resemble them, in a group termed Theropsida to
+express their mammalian resemblances, it is evident that there is no one
+continuous chain of life or gradation in complexity of structure of
+animals.
+
+We have to determine whether the Ornithosauria incline towards the
+Sauropsidan or Bird-Reptile alliance, or to the Mammal-Reptile or
+Theropsidan alliance. There can be no doubt that the predominant
+tendency is to the former, with a minor affinity towards the latter.
+
+The Ornithosauria are one of a series of groups of animals, living and
+extinct, which have been combined in an alliance named the
+Ornithomorpha. That group includes at least five great divisions of
+animals, which circle about birds, known as Ornithosauria, Crocodilia,
+Saurischia, Aves, Ornithischia, and Aristosuchia. Their relations to
+each other are not evident in an enumeration, but may be shown in some
+degree in a diagram (see p. 190).
+
+
+THE ORNITHOMORPHA
+
+The Ornithomorpha arranged in this way show that the three middle
+groups--carnivorous Saurischia, Aristosuchia, herbivorous
+Ornithischia--which are usually united as Dinosauria, intervene between
+Birds and Ornithosaurs; and that the Crocodilia and Ornithosauria are
+parallel groups which are connected with Birds, by the group of
+Dinosaurs, which resembles Birds most closely.
+
+The Ornithomorpha is only one of a series of large natural groups of
+animals into which living and extinct terrestrial vertebrata may be
+arranged. And the succeeding diagram may contribute to make evident the
+relations of Ornithosauria to the other terrestrial vertebrata (see p.
+191).
+
+Herein it is seen that while the Ornithomorpha approach towards Mammalia
+through the Ornithosauria, and less distinctly through the Crocodilia,
+they approach more directly to the Sauromorpha, through the Plesiosaurs
+and Hatteria; while that group also approaches more directly to the
+Mammals through the Plesiosaurs and Anomodonts.
+
+  [Illustration: DIAGRAM OF THE AFFINITIES OF THE ORDERS OF ANIMALS
+  COMPRISED IN THE ORNITHOMORPHA.
+
+  After a diagram in the _Philosophical Transactions of the Royal
+  Society_, 1892.]
+
+The Aristosuchia is imperfectly known, and therefore to some extent a
+provisional group. It is a small group of animals.
+
+  [Illustration: DIAGRAM SHOWING THE RELATIONS OF THE ORNITHOMORPHA
+  TO THE CHIEF LARGE GROUPS OF TERRESTRIAL VERTEBRATA, AND THEIR
+  AFFINITIES WITH EACH OTHER.
+
+  After a diagram in the _Philosophical Transactions of the Royal
+  Society_, 1892.]
+
+Cordylomorpha are Ichthyosaurs and the Labyrinthodont group.
+Herpetomorpha include Lacertilia, Homoeosauria, Dolichosauria,
+Chameleonoidea, Ophidia, Pythonomorpha.
+
+The Sauromorpha comprises the groups of extinct and living Reptiles
+named Chelonia, Rhynchocephala, Sauropterygia, Anomodontia, Nothosauria,
+and Protorosauria. These details may help to explain the place which has
+been given to the Ornithosauria in the classification of animals.
+
+  [Illustration: FIG. 75.  COMPARISON OF SIX GENERA
+
+  The skulls are seen on the left side in the order of the names below
+  them]
+
+Turning to the Pterodactyles themselves, Von Meyer divided them
+naturally into short-tailed and long-tailed. The short-tailed indicated
+by the name Pterodactylus he further divided into long-nosed and
+short-nosed. The short-nosed genus has since been named Ptenodracon
+(Fig. 59, p. 167). The long-tailed group was divided into two types--the
+Rhamphorhynchus of the Solenhofen Slate (Fig. 56, p. 161) and the
+English form now known as Dimorphodon (Fig. 52, p. 150), which had been
+described from the Lias.
+
+The Cretaceous Pterodactyles form a distinct family. So that, believing
+the tail to have been short in that group (Fig. 58), there are two
+long-tailed as well as two short-tailed families, which were defined
+from their typical genera Pterodactylus, Ornithocheirus,
+Rhamphorhynchus, and Dimorphodon.
+
+The differences in structure which these animals present are, first: the
+big-headed forms from the Lias like Dimorphodon, agree with the
+Rhamphorhynchus type from Solenhofen in having a vacuity in the skull
+defined by bone, placed between the orbit of the eye and the nostril.
+With those characters are correlated the comparatively short bones which
+correspond to the back of the hand termed metacarpals, and the tail is
+long, and stiffened down its length with ossified tendons. These
+characters separate Ornithosaurs with long tails from those with short
+tails.
+
+The short-tailed types represented by Pterodactylus and Ornithocheirus
+have no distinct antorbital vacuity in the skull defined by bone. The
+metacarpal bones of the middle hand are exceptionally elongated, and the
+tail, which was flexible in both, appears to have been short. These
+differences in the skeleton warrant a primary division of flying
+reptiles into two principal groups.
+
+The short-tailed group, which was recognised by De Blainville as
+intermediate between Birds and Reptiles, may take the name
+Pterodactylia, which he suggested as a convenient, distinctive name. It
+may probably be inconvenient to enlarge its significance to comprise not
+only the true Pterodactyles originally defined as Pterosauria, but the
+newer Ornithostoma and Ornithocheirus which have been grouped as
+Ornithocheiroidea.
+
+The second order, in which the wing membrane appears to have had a much
+greater extent, in being carried down the hind limbs, where the
+outermost digit and metatarsal are modified for its support, has been
+named Pterodermata, to include the types which are arranged around
+Rhamphorhynchus and Dimorphodon.
+
+Both these principal groups admit of subdivision by many characters in
+the skeleton, the most remarkable of which is afforded by the pair of
+bones carried in front of the pubes, and termed prepubic bones. In the
+Pterodactyle family the bones in front of the pubes are always separate
+from each other, always directed forward, and have a peculiar fan-shaped
+form with concave sides like the bone which holds a similar position in
+a Crocodile. In the Ornithocheirus family the prepubic bones appear to
+have been originally triangular, but were afterwards united so as to
+form a strong continuous bar which extends transversely across the
+abdomen in advance of the pubic bones. This at least is the distinctive
+character in the genus Ornithostoma according to Professor Williston,
+which in many ways closely resembles Ornithocheirus.
+
+The two families in the long-tailed order named Pterodermata are
+separated from each other by a similar difference in their prepubic
+bones. In Dimorphodon those bones are separate from each other, and
+remain distinct through life, meeting in the middle line of the body in
+a wide plate. On the other hand, in Rhamphorhynchus the prepubic bones,
+which are at first triangular and always slender, become blended
+together into a slight transverse bar, which only differs from that
+attributed to Ornithostoma in its more slender bow-shaped form.
+
+  [Illustration: FIG. 76.  LEFT SIDE OF PELVIS OF ORNITHOSTOMA
+  (After Williston)]
+
+Thus if other characters of the skeleton are ignored and a
+classification based upon the structure of the pelvis and prepubic
+bones, there would be some ground for associating the long-tailed
+Rhamphorhynchus from the Upper Oolites which is losing the teeth in the
+front of its jaw with the Cretaceous Ornithostoma, which has the teeth
+completely wanting; while the long-tailed Dimorphodon would come into
+closer association with the short-tailed Pterodactylus. The drum-stick
+bone or tibia in Dimorphodon, with its slender fibula, like that of a
+Bird, also resembles a Bird in the rounded and pulley-shaped terminal
+end which makes the joint corresponding to the middle of the ankle bones
+in man. The same condition of a terminal pulley joint is found in the
+Cretaceous Pterodactyles. But in the true Pterodactyles and in
+Rhamphorhynchus there usually is no pulley-shaped termination to the
+lower end of the drum-stick, for the tarsal bones remain separate from
+each other, and form two rows of ossifications, showing the same
+differences as separate Dinosaurs into the divisions which have been
+referred to, from their Bird-like pelvis and tibio-tarsus, as
+Ornithischia in the one case, and Saurischia in the other from their
+bones being more like those of living Lizards.
+
+
+
+
+CHAPTER XVII
+
+FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM
+
+
+Enough has been said of the general structure of Pterodactyles and the
+chief forms which they assumed while the Secondary rocks were
+accumulating, to convey a clear idea of their relations to the types of
+vertebrate animals which still survive on the earth. We may be unable to
+explain the reasons for their existence, and for their departure from
+the plan of organisation of Reptiles and Birds. But the evidence has not
+been exhausted which may elucidate their existence. Sometimes, in
+problems of this kind, which involve comparison of the details of the
+skeleton in different animals, it is convenient to imagine the
+possibility of changes and transitions which are not yet supported by
+the discovery of fossil remains. If, for example, the Pterodactyle be
+conceived of as divested of the wing finger, which is its most
+distinctive character, or that finger is supposed to be replaced by an
+ordinary digit, like the three-clawed digits of the hand which we have
+regarded as applied to the ground, where, it may be asked, would the
+animal type be found which approximates most closely to a Pterodactyle
+which had been thus modified? There are two possible replies to such a
+question, suggested by the form of the foot. For the old Bird
+Arch�opteryx has three such clawed digits, but no wing finger. And some
+Dinosaurs also have the hand with three digits terminating in claws,
+which are quite comparable to the clawed digits of Pterodactyles.
+
+The truth expressed in the saying that no man by taking thought can add
+a cubit to his stature is of universal application in the animal world,
+in relation to the result upon the skeleton of the exercise of a
+function by the individual. Yet such is the relation in proportions of
+the different parts of the animal to the work which it performs, so
+marked is the evidence that growth has extended in direct relation to
+use of organs and active life, and that structures have become dwarfed
+from overwork, or have wasted away from disuse--seen throughout all
+vertebrate animals, that we may fairly attribute to the wing finger some
+correlated influence upon the proportions of the animal, as a
+consequence of the dependence of the entire economy upon each of its
+parts. Therefore if an allied animal did not possess a wing finger, and
+did not fly, it might not have developed the lightness of bone, or the
+length of limb which Pterodactyles possess.
+
+The mere expansion of the parachute membrane seen in so-called flying
+animals, both Mammals and Reptiles, which are devoid of wings, is
+absolutely without effect in modifying the skeleton. But when in the Bat
+a wing structure is met with which may be compared to a gigantic
+extension of the web foot of the so-called Flying Frog, the bones of the
+fingers and the back of the hand elongate and extend under the stimulus
+of the function of flight in the same way as the legs elongate in the
+more active hoofed animals, with the function of running. Therefore it
+is not improbable that the limbs shared to some extent in growth under
+stimulus of exercise which developed the wing finger. And if an animal
+can be found among fossils so far allied as to indicate a possible
+representative of the race from which these Flying Dragons arose, it
+might be expected to be at least shorter legged, and possibly more
+distinctly Reptilian in the bones of the shoulder-girdle which support
+the muscles used in flight. It may readily be understood that the kinds
+of life which were most nearly allied to Pterodactyles are likely to
+have existed upon the earth with them, and that flight was only one of
+the modes of progression which became developed in relation to their
+conditions of existence. The principal assemblage of terrestrial animals
+available for such comparison is the Dinosauria. They may differ from
+Pterodactyles as widely as the Insectivora among Mammals differ from
+Bats, but not in a more marked way. Comparisons will show that there are
+resemblances between the two extinct groups which appeal to both reason
+and imagination.
+
+Dinosaurs are conveniently divided by characters of the pelvis first
+into the order Saurischia, which includes the carnivorous Megalosaurus
+and the Cetiosaurus, with the pelvis on the Reptile plan; and secondly
+the order Ornithischia, represented by Iguanodon, with the pelvis on the
+Bird plan. It may be only a coincidence, but nevertheless an interesting
+one, that the characters of those two great groups of reptiles, which
+also extend throughout the Secondary rocks, are to some extent
+paralleled in parts of the skeleton of the two divisions of
+Pterodactyles. This may be illustrated by reference to the skull,
+pelvis, hind limb, and the pneumatic condition of the bones.
+
+  [Illustration: FIG. 77.  COMPARISON OF THE SKULL OF THE DINOSAUR
+  ANCHISAURUS WITH THE ORNITHOSAUR DIMORPHODON]
+
+The Saurischian Dinosauria have an antorbital vacuity in the side of the
+skull between the nasal opening and the eye, as in the long-tailed
+Ornithosaurs named Pterodermata. In some of the older genera of these
+carnivorous Dinosaurs of the Trias, the lateral vacuities of the head
+are as large as in Dimorphodon. But in some at least of the Iguanodont,
+or Ornithischian Dinosaurs, there is no antorbital vacuity, and the side
+of the face in that respect resembles the short-tailed Pterodactylia.
+The skull of a carnivorous Dinosaur possesses teeth which, though easily
+distinguished from those of Pterodactyles, can be best compared with
+them. The most striking difference is in the fact that in the Dinosaur
+the nostrils are nearly terminal, while in the Pterodactyle they are
+removed some distance backward. This result is brought about by growth
+taking place, in the one case at the front margin of the maxillary bone
+so as to carry the nostril forward, and in the other case at the back
+margin of the premaxillary bone. Thus an elongated part of the jaw is
+extended in front of the nostril. Hence there is a different proportion
+between the premaxillary and maxillary bones in the two groups of
+animals, which corresponds to the presence of a beak in a bird, and its
+absence in living reptiles. It is not known whether the extremity of the
+Pterodactyle's beak is a single bone, the intermaxillary bone, such as
+forms the corresponding toothless part of the jaw in the South African
+reptile Dicynodon, or whether it is made by the pair of bones called
+premaxillaries which form the extremity of the jaw in most Dinosaurs.
+Too much importance may perhaps be attached to such differences which
+are partly hypothetical, because the extinct Ichthyosaurus, which has an
+exceptionally long snout, has the two premaxillary bones elongated so as
+to extend backward to the nostrils. A similar elongation of those bones
+is seen in Porpoises, which also have a long snout; and the bones are
+carried back from the front of the head to the nostrils, which are
+sometimes known as blowholes. But the Porpoise has those premaxillary
+bones not so much in advance of the bones which carry teeth named
+maxillary, as placed in the interspace between them. The nostrils,
+however, are not limited to the extremity of the head in all Dinosaurs.
+If this region of the beak in Dimorphodon be compared with the
+corresponding part of a Dinosaur from the Permian rocks, or Trias, the
+relation of the nostril to the bones forming the beak may be better
+understood.
+
+  [Illustration: FIG. 78.  COMPARISON OF THE SKULL OF THE DINOSAUR
+  ORNITHOSUCHUS WITH THE ORNITHOSAUR DIMORPHODON]
+
+In the sandstone of Elgin, usually named Trias, a small Dinosaur is
+found, which has been named Ornithosuchus, from the resemblance of its
+head to that of a Bird. Seen from above, the head has a remarkable
+resemblance to the condition in Rhamphorhynchus, in the sharp-pointed
+beak and positions of the orbits and other openings. In side view the
+orbits have the triangular form seen in Dimorphodon, and the preorbital
+vacuities are large, as in that genus, while the lateral nostrils, which
+are smaller, are further forward in the Dinosaur. The differences from
+Dimorphodon are in the articulation for the jaw being carried a little
+backward, instead of being vertical as in the Pterodactyle, and the bone
+in front of the nose is smaller. Notwithstanding probable differences
+in the palate, the approximation, which extends to the Crocodile-like
+vacuity in the lower jaw, is such that by slight modification in the
+skull the differences would be substantially obliterated by which the
+skull of such an Ornithosaur is technically distinguished from such a
+Dinosaur.
+
+The back of the skull is clearly seen in the Whitby Pterodactyle, and
+its structure is similar to the corresponding part of such Dinosaurs as
+Anchisaurus or Atlantosaurus, without the resemblance quite amounting to
+identity, but still far closer than is the resemblance between the same
+region in the heads of Crocodiles, Lizards, Serpents, Chelonians. Few of
+these fossil Dinosaur skulls are available for comparison, and those
+differ among themselves. The coincidences rather suggest a close
+collateral relation than prove the elaboration of one type from the
+other. They may have had a common ancestor.
+
+The Trias rocks near Stuttgart have yielded Dinosaurs as unlike
+Pterodactyles as could be imagined, resembling heavily armoured
+Crocodiles, in such types as the genus Belodon. Its jaws are compressed
+from side to side, as in many Pterodactyles, and the nostrils are at
+least as far backward as in Rhamphorhynchus. Belodon has preorbital
+vacuities and postorbital vacuities, but the orbit of the eye is never
+large, as in Pterodactyles. It might not be worth while dwelling on such
+points in the skull if it were not that the pelvis in Belodon is a basin
+formed by the blending of the expanded plates of the ischium and the
+pubis, into a sheet of bone which more nearly resembles the same region
+in Pterodactyles than does the ischio-pubic region in other Dinosaurian
+animals like Cetiosaurus.
+
+The backbone in a few Dinosaurs is suggestive of Pterodactyles. In such
+genera as have been named Coelurus and Calamospondylus, in which the
+skeleton is only partially known, the neck vertebr� become elongated, so
+as to compare with the long-necked Pterodactyles. The cervical rib is
+often very similar to that type, and blended with the vertebra, as in
+Pterodactyles and Birds. The early dorsal vertebr� of Pterodactyles
+might almost be mistaken for those of Dinosaurs. The tail vertebr� of a
+Pterodactyle are usually longer than in long-tailed Dinosauria.
+
+In the limbs and the bony girdles which support them there is more
+resemblance between Pterodactyles and Dinosaurs than might have been
+anticipated, considering their manifest differences in habit. Thus all
+Dinosaurs have the hip bone named ilium prolonged in front of the
+articulation for the femur as well as behind it, almost exactly as in
+Pterodactyles and Birds (see p. 95). There is some difference in the
+pubis and ischium which is more conspicuous in form than in direction of
+the bones. There is a Pterodactyle imperfectly preserved, named
+_Pterodactylus dubius_, in which the ischium is directed backward and
+the pubis downward, and the bones unite below the acetabular cavity for
+the head of the femur to work in, but do not appear to be otherwise
+connected. In Rhamphorhynchus the connexion between these two thickened
+bars is made by a thin plate of bone. In such a Dinosaur as the American
+carnivorous Ceratosaurus the two bars of the pubis and ischium remain
+separate and diverging, and there is no film of bone extending over the
+interspace between them. The development of such a bony condition would
+make a close approximation between the Ornithosaurian pelvis and that
+of those Dinosaurs which closely resemble Pterodactyles in skull and
+teeth.
+
+  [Illustration: FIG. 79.  LEFT SIDE OF PELVIS
+  A Pterodactyle is shown between a carnivorous Dinosaur above and a
+  herbivorous Dinosaur below]
+
+Another pelvic character of some interest is the blending of the pubis
+and ischium of the right and left sides in the middle line of the body.
+There are some genera of Dinosaurs like the English Aristosuchus from
+the Weald, and the American genera Coelurus, Ceratosaurus, and others,
+in which the pubic bones, instead of uniting at their extremities, are
+pinched together from side to side, and unite down the lower part of
+their length, terminating in an expanded end like a shoe, which is seen
+to be a separate ossification, and probably formed by a pair of
+ossifications joined in the median line. This small bone, which is below
+the pubes, and in these animals becomes blended with them, we may regard
+as a pair of prepubic bones like those of Pterodactyles and Crocodiles,
+except that they have lost the stalk-like portions, which in those
+animals are developed to compensate for the diminished length of the
+pubic bones. The prepubic bones may also be developed in Iguanodon, in
+which a pair of bones of similar form remains throughout life in advance
+of the pubes, as in Pterodactyles. In those Dinosauria with the
+Bird-like type of pelvis the pubic bone is exceptionally developed,
+sending one process backward and another process forward, so that there
+is a great gap between these diverging limbs to the bone. In the region
+behind the sternum to which the ribs were attached, and in front of the
+pelvis, is a pair of bones in Iguanodon shaped like the prepubic bones
+of Dimorphodon. They have sometimes been interpreted as a hinder part of
+the sternum, but may more probably be regarded as a pair of prepubic
+bones articulating each with the anterior process of the pubis (see Fig.
+80). The small bones found at the extremities of the pubes in such
+carnivorous Dinosaurs as Aristosuchus are blended by bony union with the
+pubes. The bones in Iguanodon are placed behind the sternal region
+without any attachment for sternal ribs, and the expanded processes
+converge forwards from the stalk and unite exactly like the prepubic
+bones of Ornithosaurs. While this character, on the one hand, may link
+Pterodactyles with the Dinosaurs, on the other hand it may be a link
+between both those groups and the Crocodiles, in which the front pair of
+bones of the pelvis has also appeared to be representative of the
+prepubic bones of Flying Reptiles (see Fig. 32, p. 98).
+
+  [Illustration: FIG. 80.  DIAGRAM OF THE PELVIS SEEN FROM BELOW IN AN
+  ORNITHOSAUR AND A DINOSAUR]
+
+The resemblances between Pterodactyles and Dinosaurs in the hind limb
+are not of less interest, though it is rather in the older Pterodactyles
+such as Dimorphodon, Pterodactylus, and Rhamphorhynchus that the
+resemblance is closest with the slender carnivorous Dinosaurs. They
+never have the head of the thigh bone, femur, separated from its shaft
+by a constricted neck, as in the Pterodactyles from the Chalk. In many
+ways the thigh bone of Dinosaurs tends towards being Avian; while that
+of Pterodactyles inclines towards being Mammalian, but with a tendency
+to be Bird-like in the older types, and to be Mammal-like in the most
+recent representatives of the group in the Chalk.
+
+The bones of the leg in Ornithosaurs, known as tibia and fibula, are
+remarkable for the circumstance first that they resemble Birds in the
+fibula being slender and only developed in its upper part towards the
+femur, and secondly that in a genus like Dimorphodon this drum-stick
+bone has the two upper bones of the ankle blended with the tibia, so as
+to form a rounded pulley joint which is indistinguishable from that of a
+Bird (see p. 102). There is a large number of Dinosaurs in which this
+remarkable distinctive character of Birds is also found. Only, Dinosaurs
+like Iguanodon, for instance, have the slender fibula as long as the
+tibia, and contributing to unite with the separate ankle bones of the
+similarly rounded pulley at the lower end. There are no Birds in which
+the tarsal bones remain separated and distinct throughout life. But in
+Pterodactylus from Solenhofen, as in a number of Dinosaurs, especially
+the carnivorous genera, the bones of the tarsus remain distinct
+throughout life, and never acquired such forms as would have enabled the
+ankle bone, termed astragalus, to embrace the extremity of the tibia, as
+it does in Iguanodon. Thus the resemblance of the Ornithosaur drum-stick
+is almost as close to Dinosaurs as to Birds.
+
+There is great similarity between Dinosaurs and Pterodactyles seen in
+the region of the instep, known as the metatarsus. These bones are
+usually four in number, parallel to each other, and similar in form.
+They are commonly longer than in Dinosaurs; but among some of the
+carnivorous Dinosaurs their length approximates to that seen in
+Pterodactyles. In neither group are the bones blended together by bony
+union, while they are always united in Birds, as in Oxen and similar
+even-hoofed mammals. Dinosaurs agree with Pterodactyles in maintaining
+the metatarsal bones separate, but they differ from them and agree with
+Birds frequently, in having the number of metatarsal bones reduced to
+three, as in Iguanodon, though Dinosaurs often have as many as five
+digits developed.
+
+The toe bones, the phalanges of these digits of the hind limb, are
+usually longer in Pterodactyles than in Dinosaurs, but they resemble
+carnivorous Dinosaurs in the forms of their sharp terminal bones for the
+claws, which are similarly compressed from side to side.
+
+So diverse are the functions of the fore limb in Dinosaurs and
+Pterodactyles, and so remarkably does the length of the metacarpal
+region of the back of the hand vary in the long-tailed and short-tailed
+Ornithosaurs, that there is necessarily a less close correspondence in
+that region of the skeleton between these two groups of animals; for the
+Pterodactyle fore limb is modified in relation to a function which can
+only be paralleled among Birds and Bats; and yet neither of those groups
+of animals approximates closely in this region of the skeleton to the
+Flying Reptile. Under all the modifications of structure which may be
+attributed to differences of function, some resemblance to Dinosaurs may
+be detected, which is best evident in the upper arm bone, humerus; is
+slight in the fore-arm bones, ulna and radius; and becomes lost towards
+the extremity of the limb.
+
+If the tendency of the thigh bone to resemble a Mammalian type of femur
+(p. 100) is a fundamental, deep-seated character of the skeleton, it
+might be anticipated that a trace of Mammalian character would also be
+found in the humerus. For what the character is worth, the head of the
+humerus does show a closer approximation to a Monotreme Mammal than is
+seen in Birds, and is to some extent paralleled in those South African
+reptiles which approximate to Mammals most closely. Not the least
+remarkable of the many astonishing resemblances of these light aerial
+creatures to the more heavy bodied Dinosaurs is the circumstance that
+the humerus in both groups makes a not dissimilar approach to that of
+certain Mammals.
+
+These illustrations may be accepted as demonstrating a relationship
+between the Ornithosaurs and Dinosaurs now compared, which can only be
+explained as results of influence of a common parentage upon the forms
+of the bones. But more interesting than resemblances of that kind is the
+similarity that may be traced in the way in which air is introduced into
+cavities in the bones in both groups. In some of the imperfectly known
+Dinosaurs, like Aristosuchus, Coelurus, and Thecospondylus, the bone
+texture is as thin as in Pterodactyles, and the vertebr� are excavated
+by pneumatic cavities, which are amazing in size when compared with the
+corresponding structures in birds, for the vertebra is often hollowed
+out so that nothing remains but a thin external film like paper for its
+thickness. In the Dinosaurian genus Coelurus this condition is as well
+marked in the tail and back as it is in the neck. The essential
+difference from Birds appears to be that in the larger carnivorous
+Dinosaurs the pneumatic condition of the bones is confined to the
+vertebral column; while Birds and Pterodactyles have the pneumatic
+condition more conspicuously developed in the limb bones. The pneumatic
+skeleton, however, appears to be absent from the herbivorous types like
+Iguanodon and all Dinosaurs which have the Bird-like form of pelvis, and
+are most Bird-like in the forms of bones of the hind limb. It is
+possible that some of the carnivorous Dinosaurs also possessed limb
+bones with pneumatic cavities. Many of those bones are hollow with very
+thin walls. If their cavities were connected with the lungs the foramina
+are inconspicuous and unlike the immense holes seen in the sides of the
+vertebr�.
+
+According to the late Professor Marsh, the limbs of Coelurus and its
+allies, which at present are imperfectly known, are in some cases
+pneumatic. Therefore there is a closer fundamental resemblance between
+some carnivorous Dinosaurs and Pterodactyles than might have been
+anticipated. But the skull of Coelurus is unknown, and the fragments of
+the skeleton hitherto published are insufficient to do more than show
+that the two types were near in kindred, though distinct in habit. Each
+has elaborated a skeleton which owes much to the common stock which
+transmitted the vital organs, and the tendency of the bones to take
+special forms; but which also owes more than can be accurately measured
+to the action of muscles in shaping the bones and the influence of the
+mechanical conditions of daily life upon the growth of the bones in both
+of these orders of animals. Enough is known to prove that all Dinosaurs
+cannot be regarded as Ornithosaurs which have not acquired the power of
+flight; though the evidence would lead us to believe that the primitive
+Ornithosaur was a four-footed animal, before the wing finger became
+developed in the fore limb as a means of extending a patagial membrane,
+like the membrane which in the hind limb of Dimorphodon has bent the
+outermost digit of the foot upward and outward to support the
+corresponding organ of flight extending down the hind legs.
+
+It may thus be seen that the characters of Ornithosaurs which have
+already been spoken of as Reptilian, as distinguished from the
+resemblances to Birds, may now with more accuracy be regarded as
+Dinosaurian. The Dinosaurs, like Pterodactyles, must be regarded as
+intermediate in some respects between Reptiles and Birds. The
+resemblances enumerated would alone constitute a partial transition from
+the Reptile to the Bird, although no Dinosaurs have organs of flight;
+many are heavily armoured with plates of bone, and few, if any,
+approximate in the technical parts of the skeleton to the Bird class,
+except in the hind limbs. Yet Dinosaurs have sometimes been regarded as
+standing to Birds in the relation of ancestors, or as parallel to an
+ancestral stock.
+
+Before an attempt can be made to estimate the mutual relation of the
+Flying Reptiles to Dinosaurs on the one hand, and to Birds on the other,
+it may be well to remember that the resemblance of such a Dinosaur as
+Iguanodon to a Bird in its pelvis and hind limb is not more remarkable
+than that of Pterodactyles to Birds in the shoulder-girdle and bones of
+the fore limb. The keeled sternum, the long, slender coracoid bones and
+scapul�, are absolutely Bird-like in most Ornithosaurs; and that region
+of the skeleton only differs from Birds in the absence of a furculum
+which represents the clavicles, and is commonly named the
+"merry-thought." The elongated bones of the fore-arm and the hand,
+terminating in three sharp claws, are characters in which the fossil
+bird Arch�opteryx resembles the Pterodactyle Rhamphorhynchus, a
+resemblance which extends to a similar elongation of the tail. It is
+remarkable that the resemblance should be so close, since Arch�opteryx
+affords the only bird's skeleton known to be contemporary which can be
+compared with the Solenhofen Flying Reptiles. The resemblance may
+possibly be closer than has been imagined. The back of the head of
+Arch�opteryx is imperfectly preserved in the region of the quadrate
+bone, malar arch, and temporal vacuity. And till these are better known
+it cannot be affirmed that the back of the head is more Reptilian in
+Pterodactyles than in the oldest Birds. The side of the head in
+Arch�opteryx is distinguished by the nostril being far forward, the
+vacuity in front of the orbit being as large as in the Pterodactyle
+Scaphognathus from Solenhofen and other long-tailed Pterodactyles.
+
+
+
+
+CHAPTER XVIII
+
+HOW PTERODACTYLES MAY HAVE ORIGINATED
+
+
+Ornithosauria have many characters inseparably blended together which
+are otherwise distinctive of Reptiles, Birds, and Mammals, and
+associated with peculiar structures which are absent from all other
+animals. They are not quite alone in this incongruous combination of
+different types of animals in the same skeleton. Dinosaurs, which were
+contemporary with Ornithosaurs, approximate to them in blending
+characters of Birds with the structure of a Reptile and something of a
+Mammal in one animal. If an Ornithosaur is Reptilian in its backbone, in
+the articular ends of each vertebra having the cup in front and ball
+behind in the manner of Crocodiles, Serpents, and many Lizards, a
+Dinosaur like Iguanodon, which had the reversed condition of ball in
+front and cup behind in its early vertebr�, may be more Mammalian than
+Avian in a corresponding resemblance of the bones to the neck in hoofed
+Mammals. But while Pterodactyles are sometimes Mammalian in having the
+head of the thigh bone moulded as in carnivorous Mammals and Man, the
+corresponding bone in a Dinosaur is more like that of a Bird. And while
+the Pterodactyle shoulder-girdle is often absolutely Bird-like, that
+region in Dinosaurs can only be paralleled among Reptiles.
+
+Such combinations of diverse characters are not limited to animals which
+are extinct. There were not wanting scientific men who regarded the
+Platypus of Australia, when first sent to Europe, as an ingenious
+example of Eastern skill, in which an animal had been compounded
+artificially by blending the beak of a Bird with the body of a Mammal.
+Fuller knowledge of that remarkable animal has continuously intensified
+wonder at its combination of Mammal, Bird, and Reptile in a single
+animal. It has broken down the theoretical divisions between the higher
+Vertebrata, demonstrating that a Mammal may lay eggs like a Reptile or
+Bird, that the skull may include the reptilian characters of the malar
+arch and pre-frontal and post-frontal bones, otherwise unknown in
+Mammals and Birds. The groups of Mammals, Birds, and Reptiles now
+surviving on the earth prove to be less sharply defined from each other
+when the living and extinct types are considered together. But in
+Pterodactyles, Mammal Bird and Reptile lose their identity, as three
+colours would do when unequally mixed together.
+
+This mingling of characteristics of different animals is not to be
+attributed to interbreeding, but is the converse of the combination of
+characters found in hybrid animals. It is no exaggeration to say that
+there is a sense in which Mammal, Bird, Reptile, and the distinctive
+structures of the Ornithosaur, have simultaneously developed from one
+egg, in the body of one animal.
+
+The differences between those vertebrate types of animals consist
+chiefly in the way in which their organisation is modified, by one
+strain of characters being eliminated so that another becomes
+predominant, while a distinctive set of structures is elaborated in each
+class of animals. The earlier geological history of the higher
+Vertebrata is very imperfectly known, but the evidence tends to the
+inference that the older representatives of the several classes
+approximate to each other more closely than do their surviving
+representatives, so that in still earlier ages of time the distinction
+between them had not become recognisable. The relation of the great
+groups of animals to each other, among Vertebrata, is essentially a
+parallel relation, like the colours of the solar spectrum, or the
+parallel digits of the hand. It was natural, when only the surviving
+life on the earth was known, to imagine that animals were connected in a
+continuous chain by successive descent, but Mammals have given no
+evidence of approximation to Birds; and Birds discover no evidence that
+their ancestors were Reptiles, in the sense in which that word is used
+to define animals which now exist on the earth. When the variation which
+animals attain in their maturity and exhibit in development from the egg
+was first realised, it was imagined that Nature, by slow summing up and
+accumulation of differences which were observed, would so modify one
+animal type that it would pass into another. There is little evidence to
+support belief that the changes between the types of life have been
+wrought in that way. The history of fossil animals has not shown
+transitions of this kind from the lower to higher Vertebrata, but only
+intermediate, parallel groups of animals, analogous to those which
+survive, and distinct from them in the same way as surviving groups are
+distinct from each other. The circumstance that Mammals, Birds, and
+Reptiles are all known low down in the Secondary epoch of geological
+time, is favourable to the idea of their history being parallel rather
+than successive. Such a conception is supported by the theory of
+elimination of characters from groups of animals as the basis of their
+differentiation. This loss appears always to be accompanied by a
+corresponding gain of characters, which is more remarkable in the soft,
+vital organs than in the skeleton. The gain in higher Vertebrates in the
+bones is chiefly in the perfection of joints at their extremities; but
+the gain in brain, lungs, heart, and other soft parts is an elaboration
+of those structures and an increase in amount of tissue.
+
+The resemblances of Ornithosaurs to Mammals are the least conspicuous of
+their characters. Those seen in the upper arm bone and thigh bone are
+manifestly not derived from Mammals. They cannot be explained as
+adaptations of the bones to conditions of existence, because there is no
+community of habit to be inferred between Pterodactyles and Mammals, in
+which the bones are in any way comparable.
+
+Other fossil animals show that a fundamentally Reptilian structure is
+capable of developing in the Mammalian direction in the skull, backbone,
+shoulder-girdle, hip-girdle, and limbs, so as to be uniformly Mammalian
+in its tendencies. This is proved by tracing the North American Texas
+fossils named Labyrinthodonts, through the South African Theriodonts,
+towards the Monotremata and other Mammalia. Just as those animals have
+obliterated all traces of the Bird from their skeletons, Birds have
+obliterated the distinctive characters of Mammals. The Ornithosaur has
+partially obliterated both. With a skull and backbone marked by typical
+characters of the Reptile, it combines the shoulder-girdle and
+hip-girdle of a Bird, with characters in the limbs which suggest both
+those types in combination with Mammals.
+
+The bones have been compared in the skeleton of each order of existing
+Reptiles, and found to show side by side with their peculiar characters
+not only resemblances to the other Reptilia, but an appreciable number
+of Mammalian and Avian characters in their skeletons. The term
+"crocodile," for example, indicates an animal in which the skeleton is
+dominated by one set of peculiar characters. Crocodiles retain enough of
+the characteristics of several other orders of reptiles to show that an
+animal sprung from the old Crocodile stock might diverge widely from
+existing Crocodiles by intensifying what might be termed its dormant
+characters in the Crocodile skeleton. Comparing animals together bone by
+bone it is possible to value the modifications of form which they put
+on, and the resemblances between them, so as to separate the inherited
+wealth of an animal's affinities with ancestors or collateral groups,
+from the peculiar characters which have been acquired as an increase
+based upon its typical bony possessions or osteological capital. There
+is no part of the Pterodactyle skeleton which is more distinctly
+modified than the head of the upper arm bone, which fits into the socket
+between the coracoid bone and the shoulder-blade. The head of the
+humerus, as the articular part is named, is somewhat crescent-shaped,
+convex on its inner border, and a little concave on its outer border,
+and therefore unlike the ball-shaped head of the upper arm bone in Man
+and the higher Mammals. It is much more nearly paralleled in the little
+group of Monotremata allied to the living Ornithorhynchus. In that sense
+the head of the humerus in a Pterodactyle has some affinity with the
+lowest Mammalia, which approach nearest to Reptiles. The character might
+pass unregarded if it were not found in more striking development in
+fossil Reptiles from Cape Colony, which from having teeth like Mammals
+are named Theriodontia. In several of those South African reptiles the
+upper arm bone approaches closer to the humerus in Ornithosaurs than to
+Ornithorhynchus. Such coincidences of structure are sometimes dismissed
+from consideration and placed beyond investigation by being termed
+adaptive modifications; but there can be no hope of finding community of
+habit between the burrowing Monotreme, the short-limbed Theriodont, and
+the flying Pterodactyle which might have caused this articular part of
+the upper arm bone to acquire a form so similar in animals constructed
+so differently. If the resemblance in the humerus to Monotremes in this
+respect is not to be attributed to burrowing, neither can the crescent
+form of its upper articulation be attributed to flight; for in Birds the
+head of the bone is compressed, but always convex, and Bats fly without
+any approach to the Pterodactyle form in the head of the humerus. This
+apparently trivial character may from such comparisons be inferred to be
+something which the way of life of the animal does not sufficiently
+account for. These deepest-seated parts of the limbs are slow to adapt
+themselves to changing circumstances of existence, and retain their
+characters with moderate variation of the bones in each of the orders
+or classes of animals. It therefore is safer to regard Mammalian
+characters, as well as the resemblances which Pterodactyles show to
+other kinds of animals, as due to inheritance from a time when there was
+a common stock from which none of these animals which have been
+considered had been distinctly elaborated.
+
+A few characters of Ornithosaurs are regarded as having been acquired,
+because they are not found in any other animals, or have been developed
+only in a portion of the group. The most obvious of these is the
+elongated wing finger; but in some genera, like Dimorphodon, there is
+also a less elongation of the fifth digit of the foot, and perhaps in
+all genera there is a backward development of the first digit of the
+hand, which is without a claw, and therefore unlike the clawed digit of
+a Bat. An acquired character of another kind, which is limited to the
+Cretaceous genera, is seen in the shoulder-blade being directed
+transversely outward, so that its truncated end articulates by a true
+joint with the early vertebr� of the back, and defended the cavity
+inclosed by the ribs by a strong bony external arch. And finally, as the
+animals later in time acquire short tails, and relatively longer limbs,
+the bones of the back of the hand, termed metacarpals, acquire greater
+and distinctive length, which is not seen in the long-tailed types like
+Rhamphorhynchus.
+
+These and such-like acquired characters distinguish the class of animals
+from all groups with which it may be compared, and mark the possible
+limits of variation of the skeleton within the boundary of the order.
+But no further variation of these parts of the skeleton could make a
+transition to another order of animals, or explain how the
+Pterodactyles came into existence, because the characters which separate
+orders and classes of animals from each other differ in kind from those
+which separate smaller groups, named genera and species, of which the
+order is made up. The accumulation of the characters of genera will not
+sum up into the characters of an order or class.
+
+In making the division of Vertebrate animals into classes the skeleton
+is often almost ignored. Its value is entirely empirical and based upon
+the observed association of the various forms of bones with the more
+important characters of the brain and other vital organs. What is
+understood as a Mammalian or Avian character in the skeleton is the form
+of bone which is found in association with the soft vital organs which
+constitute an animal a Mammal or a Bird.
+
+The characters which theoretically define a Mammal appear to be the
+enormous overgrowth of the cerebral hemispheres of the brain by which
+the cerebrum comes into contact with the cerebellum, as among Birds.
+This character distinguishes both groups of animals from all Reptiles,
+recent and fossil. But in examining the mould of the interior of the
+brain case it is rare to have the bones fitting so closely to the brain
+as to prove that the lateral expansion below the cerebrum and cerebellum
+is formed by the optic lobes of the brain. Otherwise the brain of a
+Pterodactyle might be as like to the brain of Ornithorhynchus as it is
+like that of a Bird (Fig. 19). But it is precisely in this condition of
+arrangement of the parts of the brain that the specimens appear to be
+most clear. The lateral mass of brain in specimens of Ornithosaurs from
+the Lower Secondary rocks appears to be transversely divided into back
+and front parts, which may be thought to correspond to the structures in
+a Mammal brain named _corpora quadrigemina_, but to be placed as the
+optic lobes are placed in Birds, and to have relatively greater
+dimensions than in Mammals. No evidence has been observed of this
+transverse division of the optic lobes of the brain in Pterodactyles
+from the Chalk and Cretaceous rocks, and so far as the evidence goes
+this part of the brain was shaped as in birds, but rather smaller.
+
+The brain is the only soft organ in which a Mammalian character could be
+evidenced. The uniformity in character of the brain throughout the group
+in Mammals is remarkable, in reference to the circumstance that the
+reproduction varies in type; the lowest, or Monotreme division, being
+oviparous. If there is no necessary connexion between the Mammalian
+brain and the prevalent condition under which the young are produced
+alive, it may be affirmed also that there is no necessary connexion
+between the form of the brain and the form of the bones, since the brain
+cavity in Theriodont reptiles shows no resemblance to that of a Mammal,
+while the bones are in so many respects only paralleled among
+Monotremata and Mammalia. The variety of forms which the existing
+Mammalian orders of animals assume, shows the astonishing range of
+structure of the skeleton which may coexist with the Mammalian brain.
+And therefore we are led to the conclusion that any other fundamental
+modification of brain--such as distinguishes the class of Birds--might
+also be associated with forms and structures of the skeleton which
+would vary in similar ways. In other words, if for convenience we define
+a Mammal by its form of brain, structure of the heart and lungs, and
+provision for nutrition of the young, without regard to the covering of
+the skin, which varies between the scales of a pangolin and the
+practically naked skin of the whale--a bird might be also defined by its
+peculiar conditions of brain and lungs, without reference to the
+feathered condition of the skin, though the feathered condition extends
+backward in time to the Upper Secondary rocks, as seen in the
+Arch�opteryx.
+
+The Avian characters of Pterodactyles are the predominant parts of their
+organisation, for the conditions of the brain and lungs shown by the
+moulds of the brain case and the thin hollow bones with conspicuous
+pneumatic foramina, give evidence of a community of vital structures
+with Birds, which is supported by characters of the skeleton. If any
+classificational value can be associated with the distribution of the
+pneumatic foramina as tending to establish membership of the same class
+for animals fashioned on the same plan of soft organs, the evidence is
+not weakened when a community of structures is found to extend among the
+bones to such distinctive parts of the skeleton as the sternum,
+shoulder-girdle, bones of the fore-arm and fore-leg; for in all these
+regions the Pterodactyle bones are practically indistinguishable from
+those of Birds. This is the more remarkable because other parts of the
+skeleton, such as the humerus and pelvis, show a partial resemblance to
+Birds, while the parts which are least Avian, like the neck bones, have
+no tendency to vary the number of the vertebr�, in the way which is
+common among Birds, following more closely the formula of the seven
+cervical vertebr� of Mammals.
+
+It would therefore appear from the vital community of structures with
+Birds, that Pterodactyles and Birds are two parallel groups, which may
+be regarded as ancient divergent forks of the same branch of animal
+life, which became distinguished from each other by acquiring the
+different condition of the skin, and the structures which were developed
+in consequence of the bony skeleton ministering to flight in different
+ways; and with different habit of terrestrial progression, this extinct
+group of animals acquired some modifications of the skeleton which Birds
+have not shown. There is nothing to suggest that Pterodactyles are a
+branch from Birds, but their relation to Birds is much closer, so far as
+the skeleton goes, than is their relation with the flightless Dinosaurs,
+with which Birds and Pterodactyles have many characters in common.
+
+On the theory of elimination of character which I have used to account
+for the disappearance of some Mammalian characters from the
+Pterodactyle, that loss is seen chiefly in the removal of the parts
+which have left a Reptilian articulation of the lower jaw with the
+skull, and the articulation of the vertebr� throughout the vertebral
+column by a modified cup-and-ball form of joint. The furculum of the
+Bird is always absent from the Pterodactyle. No specimen has shown
+recognisable clavicles or collar-bones. Judged by the standard of
+existing life, Pterodactyles belong to the same group as Birds, on the
+evidence of brain and lungs, but they belong to a different group on
+account of the dissimilar modifications of the skeleton and apparent
+absence of feathers from the skin.
+
+The most impressive facts in the Pterodactyle skeleton, in view of these
+affinities, are the structures which it has in common with Reptiles.
+Some structures are fundamental, like the cup-and-ball articulation of
+the vertebr�, which is never found in birds or mammals. Although not
+quite identical with the condition in any Reptile, this structure is
+approximately Lizard-like or Crocodile-like in the cup-and-ball
+character. It shows that the deepest-seated part of the skeleton is
+Reptile-like, though it may not be more Reptilian than is the vertebral
+column of a Mammal, if comparison is made between Mammals and extinct
+groups of animals known as Reptiles, such as Dinosaurs and Theriodontia.
+
+The orders of animals which have been included under the name Reptilia
+comprise such different structural conditions of the parts of the
+skeleton which may be termed reptilian in Ornithosaurs, that there is
+good reason for regarding the cup-and-ball articulation as quite a
+distinctive Reptilian specialisation, in the same sense that the
+saddle-shaped articulation between the bodies of adjacent vertebr� in a
+bird is an Avian specialisation. From the theoretical point of view the
+Ornithosaur acquired its Reptilian characters simultaneously with its
+Avian and Mammalian characters.
+
+There is nothing in the structure of the skeleton of the Dinosauria, to
+which Ornithosaurs approximate in several parts of the body, which would
+help to explain the cup-and-ball articulation of the backbone, if the
+Flying Reptile were supposed to be an offshoot from the carnivorous
+Dinosaurs.
+
+The elimination of Reptile characters from so much of the skeleton, and
+the substitution for them of the characters of Birds and Mammals, would
+be of exceptional interest if there had been any ground for regarding
+the flying animal as more nearly related to a Reptile than to a Bird.
+But if the evidence from the form of the brain and nature of the
+pneumatic organs seen in the limb bones accounts for the Avian features
+of the skeleton, the Reptilian condition of the vertebral column helps
+to show a capacity for variation, and that the fixity of type and
+structure, which the skeleton of the modern Bird has attained, is not
+necessarily limited to or associated with the vital organs of Birds.
+
+The variation of the cup-and-ball articulation in the neck of a
+Chelonian, which makes the third vertebra cupped behind, the fourth
+bi-convex, the fifth cupped in front, and the sixth flattened behind,
+shows that too much importance may be attached to the mode of union of
+these bones in Serpents, Crocodiles, and those Lizards which have the
+cup in front; for while in Lizards the anterior cup, oblique and
+depressed, is found in most of its groups, the Geckos show no trace of
+the cup-and-ball structure, and in that respect resemble the Hatteria of
+New Zealand.
+
+If, therefore, the cup-and-ball articulation of vertebr� in
+Ornithosauria has any significance as a mark of affinity to Reptiles, it
+could only be in approximation to those living Reptiles which possess
+the same character, and would have it on the hypothesis that both have
+preserved the structure by descent from an earlier type of animal. This
+hypothesis is negatived by the fact that the cup-and-ball articulation
+is unknown in the older fossil Reptiles.
+
+Although the articulation for the lower jaw with the skull in
+Ornithosaurs is only to be paralleled among Reptiles, the structure is
+adapted to a brain case which is practically indistinguishable from that
+of a Bird, except for the postorbital arch.
+
+The hypothesis of descent, therefore, becomes impossible, in any
+intelligible form, in explanation of distinctive character of the
+skeleton. The hypothesis of elimination may also seem to be
+insufficient, unless the potential capacity for new development be
+recognised as concurrent, and as capable of modifying each region of the
+skeleton, or hard parts of the animal, in the same way that the soft
+organs may be modified. From which we infer that all structures, which
+distinguish the several grades of organisation in modern
+classifications, soft parts and hard parts alike, may come into
+existence together, in so far as they are compatible with each other, in
+any class or ordinal division of animals.
+
+Although the young Mammal passes through a stage of growth in which the
+brain may be said to be Reptilian, there is no good ground for inferring
+that Mammal or Bird type of skeleton was developed later in time than
+that of Reptiles. The various types of Fishes have the brains in general
+so similar to those of Reptiles that it is more intelligible for all the
+vertebrate forms of brain to have differentiated at the same time, under
+the law of elimination of characters, than that there should be any
+other bond of union between the classes of animals.
+
+If we ask what started the Ornithosauria into existence, and created the
+plan of construction of that animal type, I think science is justified
+in boldly affirming that the initial cause can only be sought under the
+development of patagial membranes, such as have been seen in various
+animals ministering to flight. Such membranes, in an animal which was
+potentially a Bird in its vital organs, have owed development to the
+absence of quill feathers. Thus the wing membrane may be the cause for
+the chief differences of the skeleton by which Ornithosaurs are
+separated from Birds, for the stretch of wing in one case is made by the
+skin attached to the bones, and in the other case by feathers on the
+skin so attached as to necessitate that the wing bones have different
+proportions from Ornithosaurs.
+
+It is a well-known observation that each great epoch of geological time
+has had its dominant forms of animal life, which, so far as the earth's
+history is known now, came into existence, lived their time, and were
+seen no more. In the same way the smaller groups of species and genera
+included in an ordinal group of animals or class have abounded, giving a
+tone to the life of each geological formation, until the vitality of the
+animal is exhausted, and the species becomes extinct or ceases to
+preponderate. This process is seen to be still modifying the life on the
+earth, when some kinds of animals and plants are introduced to new
+conditions. Plants appear to wage successful war more easily than
+animals. The introduction of the Cactus in some parts of Cape Colony has
+locally modified both the fauna and flora, just as the Anacharis
+introduced into England spread from Cambridge over the whole country,
+and became for many years the predominant form of plant life in the
+streams. The Rabbit in Australia is a historic pest. Something similar
+to this physical fertility and increase appears to take place under new
+circumstances in certain organs within the bodies of animals, by the
+development of structures previously unknown. A familiar example is seen
+in the internal anatomy of the Trout introduced into New Zealand, where
+the number of pyloric appendages about the stomach has become rapidly
+augmented, while the size and the form of the animal have changed. The
+rapidity with which some of these changes have been brought about would
+appear to show that Nature is capable of transforming animals more
+rapidly than might have been inferred from their uniform life under
+ordinary circumstances. Growth of the vital organs in this way may
+modify the distinctive form of any vital organ, brain or lungs, and thus
+as a consequence of modification of the internal structures due to
+changes of food and habit, bring a new group of animals into existence.
+And just as the group of animals ceases to predominate after a time, so
+there comes a limit to the continued internal development of vital
+structures as their energy fails, for each organ behaves to some extent
+like an independent organism.
+
+Under such explanations of the mutual relations of the parts of animals,
+and groups of animals, time ceases to be a factor of primary importance
+in their construction or elaboration. The supposed necessity for
+practically unlimited time to produce changes in the vital organs which
+separate animals into great orders or classes is a nightmare, born of
+hypothesis, and may be profitably dismissed. The geological evidence is
+too imperfect for dogmatism on speculative questions; but the nature of
+the affinities of Ornithosaurs to other animals has been established on
+a basis of comparison which has no need of theory to justify the facts.
+It is not improbable that the primary epoch of time, even as known at
+present, may be sufficiently long to contain the parent races from which
+Ornithosaurs and all their allies have arisen.
+
+In thus stating the relation of Ornithosaurs to other animals the Flying
+Reptile has been traced home to kindred, though not to its actual
+parents or birthplace. There is no geological history of the rapid or
+gradual development of the wing finger, and although the wing membrane
+may be accepted as its cause of existence, the wing finger is powerfully
+developed in the oldest known Pterodactyles as in their latest
+representatives.
+
+Pterodactyles show singularly little variation in structure in their
+geological history. We chronicle the loss of the tail and loss of teeth.
+There is also the loss of the outermost wing digit from the hind foot as
+a supporter of the wing membrane. But the other variations are in the
+length of the metacarpus, or of the neck, or head. One of the
+fundamental laws of life necessitates that when an animal type ceases to
+adapt its organisation and modify its structures to suit the altered
+circumstances forced upon it by revolutions of the earth's surface its
+life's history becomes broken. It must bend or break.
+
+The final disappearance of these animals from the earth's history in the
+Chalk may yet be modified by future discoveries, but the Flying Reptiles
+have vanished, in the same way as so many other groups of animals which
+were contemporary with them in the Secondary period of time. Such
+extinctions have been attributed to catastrophes, like the submergence
+of land, so that the habitations of animals became an area gradually
+decreasing in size, which at last disappeared. It appears also to be a
+law of life, illustrated by many extinct groups of animals, that they
+endure for geological ages, and having fought their battle in life's
+history, grow old and unable to continue the fight, and then disappear
+from the earth, giving place to more vigorous types adapted to live
+under new conditions.
+
+The extinct Pterodactyles hold a relation to Birds in the scheme of life
+not unlike that which Monotremata hold to other Mammals. Both are
+remarkable for the variety of their affinities and resemblances to
+Reptiles. The Ornithosauria have long passed away; the Monotremes are
+nearing extinction. Both appear to be supplanted by parallel groups
+which were their contemporaries. Birds now fill the earth in a way that
+Flying Reptiles never surpassed; but their flight is made in a different
+manner, and the wing is extended to support the animal in the air,
+chiefly by appendages to the skin.
+
+If these fossils have taught that Ornithosaurs have a community of soft
+vital organs with Dinosaurs and Birds, they have also gone some way
+towards proving that causes similar to those which determined the
+structural peculiarities of their bony framework, originated the special
+forms of respiratory organs and brain which lifted them out of
+association with existing Reptiles.
+
+
+These old flying animals sleep through geological ages, not without
+honour, for the study of their story has illuminated the mode of origin
+of animals which survive them, and in cleaving the rocks to display
+their bones we have opened a new page of the book of life.
+
+
+
+
+APPENDIX
+
+
+The best public collections of Ornithosaurian remains in England are
+in the British Museum (Natural History); Museum of Practical Geology,
+Royal College of Surgeons; the University Museum, Oxford; Geological
+Museum, Cambridge; and the Museum of the Philosophical Society at
+York.
+
+Detailed descriptions and original figures of the principal specimens
+mentioned or referred to may be found in the following writings:--
+
+  H. v. Meyer, _Reptilien aus dem Lithograph_. _Schiefer_. 1859. Folio.
+  v. Quenstedt, _Pterodactylus suevicus_. 1855. 4to.
+  Goldfuss, _Nova Acta Leopold_. XV.
+  v. Munster, _Nova Acta Leopold_. XV.
+  A. Wagner, _Abhandl. Bayerischen Akad._, vi., viii.
+  Cuvier, _Annales du Museum_, xiii. 1809.
+    "     _Ossemens fossiles_, v. 1824.
+  Buckland, _Geol. Trans._, ser. 2, iii.
+  R. Owen, _Pal�ontographical Society_. 1851, 1859, 1860, 1870, 1874.
+  K. v. Zittel, _Pal�ontographica_, xxix. 1882.
+  T. C. Winkler, _Mus. Teyler Archives_. 1874, 1883.
+  Oscar Fraas, _Pal�ontographica_, xxv. 1878.
+  Anton Fritsch, _B�hm. Gesell. Sitzber_. 1881.
+  R. Lydekker, _Catalogue of Fossil Reptilia in British Museum_ I. 1888.
+  O. C. Marsh, _Amer. Jour. Science_. 1882, 1884.
+  S. W. Williston, _Kansas University Quarterly_. 1893, 1896.
+  E. T. Newton, _Phil. Trans. Royal Soc._ 1888, 1894.
+  H. G. Seeley, _Ornithosauria_. 8vo. 1870.
+      "         _Annals and Mag. Natural Hist._ 1870, 1871, 1890, 1891.
+      "         _Linn. Society_. 1874, 1875.
+      "         _Geol. Mag._ 1881.
+  Felix Pleininger, _Pal�ontographica_. 1894, 1901.
+
+
+
+
+INDEX
+
+
+A
+
+  Abdominal ribs, 85, 154
+
+  Accumulation of characters, 220
+
+  Acetabulum, 95
+
+  Acquired characters, 219
+
+  Adjacent land, 136
+
+  Air cells, 10, 48
+
+  Albatross, 23, 36, 176
+
+  Alligator, brain, 53;
+    pelvis, 98
+
+  American Greensand, 185
+
+  -- ornithosaurs, 87, 126
+
+  Amphibia, 4, 191
+
+  Anabas, 17
+
+  Anacharis, 227
+
+  Anchisaurus, 199
+
+  Angle of lower jaw, 75
+
+  Ankle bones, 103, 195, 207
+
+  Anomodonts, 192
+
+  Ant-eater of Africa, 142;
+    India, 40;
+    South America, 40, 185
+
+  Apteryx, lungs, 48;
+    pelvis, 95
+
+  Aquatic mammals, 141
+
+  Aramis, scapular arch, 113
+
+  Arch�opteryx, 58, 76, 104, 130, 197, 211
+
+  Aristosuchus, 129, 190, 205, 209
+
+  Armadillo, 40, 141
+
+  Articulation of the jaw, 12, 75
+
+  Ashwell, 177
+
+  Atlantosaurus, 202
+
+  Atlas and axis, 80, 81
+
+  Aves, 190
+
+  Avian characters, 220, 222
+
+
+B
+
+  Backbone, 78, 84
+
+  Banz, 148
+
+  Barbastelle, 25
+
+  Barrington, 177
+
+  Barton, 177
+
+  Bat, 38, 110, 197;
+    sternum of, 107;
+    metacarpus, 128
+
+  Bavaria, 156, 185
+
+  Beak, horny, 74, 178
+
+  Bear, skull of, 12;
+    femur, 100
+
+  Bel and the Dragon, 15
+
+  Belodon, 202
+
+  Bird, 80, 110, 120
+
+  -- resemblances, 63, 65, 71, 95, 102, 108, 113, 119, 120, 211
+
+  Bird-reptile, 188
+
+  Bird wing, 128, 130
+
+  Birds in flight, 22;
+    with teeth, 76
+
+  Black-headed bunting, 47
+
+  Blainville, D. de, 30, 193
+
+  Blood, temperature of, 56
+
+  Bohemia, 34
+
+  Bonaparte, Prince Charles, 30
+
+  Bones of birds, variation in, 41
+
+  -- of reptiles, variation in, 42
+
+  -- about the brain, 69
+
+  -- in the back, 84
+
+  Bone texture, 59, 209
+
+  Bonn Museum, 32, 85, 156
+
+  Brain and breathing organs, 55
+
+  Brain cavity, in birds and reptiles, 52;
+    in mammals, 221, 226;
+    in Solenhofen pterodactyles, 54, 220
+
+  Brazil, 34
+
+  Breathing organs, 8
+
+  Bridgewater Treatise, 143
+
+  British Museum, 133, 183
+
+  Brixton, Isle of Wight, 55, 174
+
+  Buckland, Dean, 143, 148, 231
+
+  Burrowing limb, 38
+
+
+C
+
+  Cactus, 227
+
+  Calamospondylus, 203
+
+  Cambridge Greensand, 33, 89, 176
+
+  -- Museum, 177
+
+  Camel, 83
+
+  Campylognathus, 68, 71, 135;
+    size of, 149
+
+  Canary, 47
+
+  Carnivorous dinosaurs, 129
+
+  Carpus, 122
+
+  Caudal fin, 91, 161
+
+  -- vertebr�, 89, 92, 203
+
+  Ceratodus, 4, 5, 9, 17
+
+  Ceratosaurus, 203, 204
+
+  Cervical rib, 81
+
+  Cetacea, 40
+
+  Cetiosaurus, 198, 203
+
+  Chalinolobus, 25
+
+  Chalk, pterodactyles in, 136;
+    of Kansas, 103, 132
+
+  Chameleon, 17, 51, 70;
+    scapula, 112;
+    sternum, 107
+
+  Chameleonoidea, 191
+
+  Cheek bones, 178
+
+  Chelonia, 86, 112, 193
+
+  Chesterton, 177
+
+  Chlamydosaurus, 21
+
+  _Chrysochloris capensis_, 121
+
+  Classification, 192;
+    on pelvis characters, 195;
+    of dinosaurs, 198
+
+  Clavicles, 111, 112
+
+  Claw, 105, 116, 183, 208
+
+  Coelurus, 203, 209
+
+  Coldham Common, 177
+
+  Collar bone, 111
+
+  Collini, 27
+
+  Comparison with dinosaurs, 198;
+    of pelvis, 204, 206;
+    of skulls, 192, 199, 201
+
+  Cope, Professor, 31, 34
+
+  Coracoid, 109, 112, 113
+
+  Cordylomorpha, 191
+
+  Cormorant, 70, 174;
+    sternum, 108
+
+  Corpora quadrigemina, 221
+
+  Crisp, Dr., on pneumatic skeleton, 47
+
+  Crocodile, characters of, 217;
+    heart, 56;
+    lung, 9;
+    shoulder-girdle, 111;
+    skull, 46;
+    vertebr�, 79
+
+  Crocodilia, 190
+
+  Curlew, 68
+
+  Cuvier, 1, 27, 28, 54, 76, 77, 130, 231
+
+  Cycnorhamphus, 70, 94, 171, 173, 204
+
+  _Cycnorhamphus Fraasii_, 80, 96, 169
+
+  -- _suevicus_, 169, 170
+
+  Cypselus, 42
+
+
+D
+
+  _Dacelo gigantea_, 63
+
+  Darwin, 3
+
+  Davy, Dr. John, 142
+
+  Deuterosaurus, 97
+
+  Dicynodon, 200
+
+  _Dicynodon lacerticeps_, 71
+
+  Digits, of ostrich, 23;
+    of pterodactyle, 128
+
+  Digits with claws, 130;
+    foot bones in, 105
+
+  Dimorphodon, 63, 64, 66, 67, 73, 74, 83, 90, 102, 113, 143, 192, 194,
+          199, 201, 206
+
+  Dinosauria, 6, 77, 84, 87, 95, 129, 144, 198, 209
+
+  Dinosaurs from Lias, 135, 192;
+    from Elgin, 201, 207;
+    Stuttgart, 202;
+    Trias dinosaurs, 199, 200
+
+  Diopecephalus, 168
+
+  Diving birds, 23, 83, 102
+
+  Dolichosauria, 191
+
+  Dolphin, 107
+
+  Doratorhynchus, 173
+
+  Dorygnathus, 74, 148
+
+  Dragons, 3, 15, 17
+
+  Drumstick bone, 103, 195
+
+  Duck, 22, 83
+
+
+E
+
+  Echidna, 75, 76, 95, 100
+
+  Edentata, 185
+
+  Edentulous beak, 153
+
+  Eichst�dt, 32
+
+  Elephant, head of, 46
+
+  Enumeration of characters, 223, 225
+
+  Ephesus, winged figure, 16
+
+  Epiphysis to first phalange, 123
+
+  Exocoetus, 18
+
+  Extinctions, 129
+
+  Eye hole, 144;
+    sclerotic bones in, 65
+
+
+F
+
+  Farren, William, 34
+
+  Femur, 100
+
+  Fibula, 102, 183, 206
+
+  Fifth outer digit, 132;
+    in foot, 145
+
+  Figure from temple at Ephesus, 16
+
+  First phalange, 151
+
+  Fish-eating crocodile, 137
+
+  Flight, organs of, 17;
+    in bats, 25
+
+  Flying limb, 38
+
+  Flying fishes, 18, 57;
+    foxes, 26;
+    frogs, 19, 197;
+    gecko, 21, 24;
+    lizards, 20;
+    reptiles, 37, 46;
+    squirrel, 24
+
+  Foot, 104;
+    digits in, 105, 146
+
+  Fore leg, 102, 206
+
+  -- limb, 38, 107, 116, 120
+
+  Four claws, 147
+
+  Fox, Rev. W., 55, 174
+
+  Fraas, Professor Oscar, 172, 231
+
+  Frigate bird, vertebr� of, 86, 174
+
+  Frog, lungs of, 8
+
+  Furculum, 114
+
+
+G
+
+  Gaudry, Professor A., 31
+
+  Gavial, 136
+
+  Gecko, 21, 23
+
+  Genera, comparison of, 192
+
+  Geological distribution, 186
+
+  Gills, 4
+
+  Giraffe, 38, 39
+
+  Glossy starling, 47
+
+  Golden eagle, 120
+
+  -- mole, 121
+
+  Goldfuss, 30, 231
+
+  Granchester, 177
+
+  Great ant-eater, 40, 185
+
+  Guillemot, 102
+
+  Gull, 22
+
+
+H
+
+  Haarlem, Teyler Museum at, 32
+
+  Habits, probable, 134, 176, 198
+
+  Hairless skins, 141
+
+  Hand in mammals, 38
+
+  Harston, 177
+
+  Haslingfield, 177
+
+  Hastings, 174
+
+  Hatteria lung, 9, 27;
+    brain, 53;
+    skull, 70, 77;
+    ribs, 86;
+    a reptile type, 13
+
+  Head, characters of, 76
+
+  Heidelberg Museum, 32, 54, 159
+
+  Herpetomorpha, 191
+
+  Heron, 65, 174
+
+  Hesperornis, 76
+
+  Hind foot, 104, 135
+
+  -- limb, 93, 99, 159, 206
+
+  Hip-girdle in whale tribe, 39, 159
+
+  Homoeosauria, 191
+
+  Horningsea, 177
+
+  Horse, metacarpus of, 127;
+    vertebr� of, 79
+
+  Humerus, 46, 117, 217
+
+  Huxley, Professor, 31, 89, 154, 188
+
+  Hyo-mandibular arch, 13
+
+  Hypothesis of descent, 226
+
+  Hyrax, 101
+
+
+I
+
+  Ichthyornis, 76
+
+  Ichthyosaurus, 6, 191
+
+  Iguanodon, 209;
+    pelvis, 206
+
+  Ilium, 93, 95, 96, 98, 204
+
+  Instep, 105, 207
+
+  Inherited characters, 217
+
+  Interclavicle, 111
+
+  Ischium, 93, 96, 203, 204
+
+  Isle of Wight, 174
+
+
+J
+
+  Jaw, in birds, 12;
+    in fishes, 13;
+    in mammals, 12;
+    in reptiles, 13;
+    in pterodactyles, 63;
+    suspension of, 11, 74, 76
+
+  -- lower, 75
+
+
+K
+
+  Kansas, Chalk of, 72, 103, 115;
+    University Museum of, 181
+
+  Kelheim, 32
+
+  Keuper, 33
+
+  Kimeridge Clay, 132
+
+  Kingfisher, 63
+
+  Kiwi, 23
+
+
+L
+
+  Labyrinthodontia, 191
+
+  Lachrymal bones, 67
+
+  Laramie rocks, 34
+
+  Largest ornithosaur, 133
+
+  Lateral vacuities in skull, 147
+
+  Lawrence in Kansas, 181
+
+  Lengths of bones, 146
+
+  Lepidosiren, 17
+
+  Lias, 33
+
+  Lithographic Slate, 35, 156
+
+  Lizards, 20, 21, 27, 123
+
+  Llama, neck of, 79, 83
+
+  Loach, swim bladder of, 52
+
+  Lower jaw, 12, 74, 76, 149
+
+  Lumbar vertebr�, 89
+
+  Lungs, 47;
+    in apteryx, 48;
+    in chameleon, 51;
+    in ostrich, 49;
+    in reptiles, 8, 9, 51
+
+  Lydekker, R., 160, 169, 231
+
+  Lyme Regis, 33
+
+
+M
+
+  Macrocercus, palate of, 71
+
+  Malar bone, 67
+
+  Mallard, 22
+
+  Mammal, 8, 12, 24, 79, 53, 95
+
+  Mammalia, 38, 141
+
+  Mammalian characters, 12, 220
+
+  Mammoth, 141
+
+  Manis, 40, 57, 142
+
+  Manubrium of sternum, 108, 109, 183
+
+  Marrow bones in a bird, 134
+
+  Marsh, Professor O. C., 31, 72, 90, 115, 121, 131, 140, 160, 165,
+          180, 181, 210, 231
+
+  Marsupial, 70, 94, 99
+
+  Megalosaurus, 129, 198
+
+  Merganser, 108
+
+  Merry-thought, 114
+
+  Metacarpus, 116, 124, 126, 128, 130
+
+  Metatarsal bones, 104, 207, 208
+
+  Meyer, Hermann von, 31, 45, 46, 85, 105, 108, 121, 160, 192, 231
+
+  Moa of New Zealand, 35
+
+  Mole, humerus, 38;
+    sternum, 107
+
+  Monotremes, 70, 94, 111, 121, 185, 218
+
+  Mososaurus, 77
+
+  Movement of the leg, 101
+
+  Mugger, 137
+
+  Munich Museum, 32, 159
+
+  Munster, von, 231
+
+  Muschelkalk, 184
+
+  Museum, 32, 156, 231, 159;
+    Natural History, 133, 231
+
+  Myrmecophaga, 185
+
+
+N
+
+  Names of genera, 183
+
+  Natural History Museum, 38, 231
+
+  Neck, 79;
+    in Dimorphodon, 145;
+    in Giraffe, 39;
+    in Llama, 79;
+    in Pterodactyles, 80;
+    in Whales, 39
+
+  Newton, E. T., 55, 70, 158, 160, 201, 232
+
+  New Zealand Bat, 25
+
+  -- -- Hatteria, 68
+
+  Niobrara rock, 183
+
+  Nostril, bones round the, 62;
+    small, 147
+
+  Notarium, 87, 115
+
+  Nothosauria, 192
+
+  Nusplingen, 32
+
+  Nyctodactylus, 115, 180
+
+
+O
+
+  Obliteration of characters, 216
+
+  Opercular bones, 13
+
+  Ophidia, 52, 191
+
+  Optic lobes, 53, 221
+
+  Organs of flight, 17
+
+  Ornithischia, 190, 198
+
+  Ornithocephalus, 166
+
+  Ornithocheirus, atlas and axis, 81;
+    brain, 55, 69;
+    carpus, 124;
+    cervical vertebra, 83, 179;
+    claw phalange, 129;
+    coracoid, 109;
+    femur, 100;
+    pelvis, 98;
+    pubic bones, 194;
+    sternum, 109;
+    shoulder-girdle, 115;
+    remains, 176;
+    teeth, 74, 76;
+    absence of teeth, 138
+
+  _Ornithocheirus mach�rorhynchus_, 139;
+    _microdon_, 139
+
+  Ornithocheiroidea, 193
+
+  Ornithodesmus, neck bones, 173, 175;
+    coracoid, 109, 116;
+    dorsal vertebr�, 86;
+    remains of _O. latidens_, 173;
+    _O. sagittirostris_, 175
+
+  Ornithomorpha, 189
+
+  Ornithorhynchus, 40, 53, 95, 117
+
+  Ornithosauria, 30, 31, 50, 52, 58, 72, 89, 95, 104, 108, 125, 132,
+          133, 143, 187, 190, 192, 216
+
+  Ornithostoma, 66, 69, 72, 180;
+    lower jaw, 75, 76;
+    pelvis, 98;
+    sternum, 110;
+    phalange, 122;
+    size, 133;
+    skull, 181, 182
+
+  Ornithosuchus, 201
+
+  Orycteropus, 96
+
+  _Ossa innominata_, 93
+
+  Ossified ligaments, 150
+
+  Ostrich, 23, 45, 49, 113, 129
+
+  Owen, Sir R., 31, 36, 46, 48, 110, 117, 143, 172, 176, 180, 231
+
+  Owl, 46, 53
+
+  Oxford Clay, 33, 156
+
+  -- University Museum, 154
+
+  Ox, vertebra of, 79;
+    metacarpus, 127
+
+
+P
+
+  Palate, bones of, 71
+
+  Pangolin, 142
+
+  Pappenheim, 32
+
+  Parallel groups, 215
+
+  Parrot, 71
+
+  Patagial membranes, 227
+
+  Pelican, 174
+
+  Pelvis, 88, 94-98, 151, 195, 202, 204, 206
+
+  Penguin, 41, 42, 104, 176
+
+  Periophthalmus, 17
+
+  Peterborough, bones from, 113, 156
+
+  Phalanges, 129, 132;
+    wing finger, 155
+
+  Phillips, Professor John, 155
+
+  Pigeon, 119
+
+  Platydactylus, 21
+
+  Platypus, 214
+
+  Plesiosaurus, 6, 73, 75, 93, 189
+
+  Pleininger, 149, 232
+
+  Pneumatic foramina, 45, 83, 88, 132, 209
+
+  Pond, Mr., 34
+
+  Porcupine, 40
+
+  Porpoise, 38, 73, 141, 200
+
+  Premaxillary bones, 77, 200, 205
+
+  Prepubic bones, 94, 96-98, 194, 204, 205
+
+  Protorosauria, 192
+
+  _Ptenodracon brevirostris_, 64, 99, 167, 169, 192
+
+  Pterodactyle aspects, 35;
+    avian characters, 222;
+    beak, 200;
+    brain, 53;
+    coracoid, 113;
+    discovery, 27, 33;
+    foot, 104;
+    fore limb, 117;
+    history in Germany, 31, 148;
+    hand, 130;
+    hind limb, 100;
+    long tails, 156;
+    palate, 71;
+    sacrum, 89;
+    short tails, 165;
+    size, 35, 133;
+    sacrum, 89;
+    skull, 192;
+    teeth, 73;
+    vertebr�, 80
+
+  Pterodactyles from Kansas Chalk, 177, 181
+
+  -- from Lias Clay, 135, 147, 152
+
+  -- from Neocomian Sand, 176
+
+  -- from Oxford Clay, 155
+
+  -- from Purbeck beds, 173
+
+  -- from Solenhofen Slate, 156, 158
+
+  -- from Stonesfield Slate, 153, 158
+
+  Pterodactylia, 30, 165, 193, 199
+
+  _Pterodactylus antiquus_, 167;
+    _brevirostris_, 99, 167, 169;
+    _crassirostris_, 156;
+    _dubius_, 87, 96, 97, 203;
+    _elegans_, 169;
+    _Fraasii_, 169;
+    _grandipelvis_, 87, 90;
+    _grandis_, 102, 167, 169;
+    _Kochi_, 12, 61, 87, 90, 168, 169;
+    _longirostris_, 28, 90, 96, 101, 103, 105, 167, 169;
+    _micronyx_, 105, 169;
+    _rhamphastinus_, 183;
+    _scolopaciceps_, 105, 166;
+    _spectabilis_, 83;
+    _suevicus_, 169
+
+  Pterodermata, 194, 199
+
+  Pteroid bone of first digit, 121
+
+  Pteromys, 24
+
+  Pterosauria, 187, 193
+
+  Pterygoid bones, 72, 147
+
+  Pythonomorpha, 191
+
+
+Q
+
+  Quadrate bone, 12, 68, 77
+
+  Quenstedt, 231
+
+
+R
+
+  Rabbit, 227
+
+  Radius, 119, 120
+
+  Redshanks, 22
+
+  Relation between head and tail, 157, 193
+
+  Reptile, 6, 79, 80
+
+  Resin, 136
+
+  Restorations--
+    Campylognathus, palate of, 71
+    Dimorphodon, 143, 147, 164
+    Ornithocheirus, 164
+    Ornithostoma, 164, 183
+    Ptenodracon, 167
+    Pterodactylus, 29, 30
+    Rhamphocephalus, 164
+    Rhamphorhynchus, 161, 164
+    Scaphognathus, 163
+
+  Rhacophorus, 19
+
+  Rh�tic beds, 184
+
+  Rhamphocephalus, 113, 136, 153
+
+  Rhamphorhynchus, 118, 192;
+    foot, 104;
+    hind limb, 99;
+    pelvis, 95;
+    sacrum, 88;
+    skull, 54, 63-6, 69;
+    sternum, 108;
+    tail, 91;
+    teeth, 73;
+    tibia and fibula, 103;
+    web-footed, 105
+
+  _Rhamphorhynchus curtimanus_, 163;
+    _hirundinaceus_, 163;
+    _longimanus_, 164;
+    _phyllurus_, 91, 165
+
+  Rhinoceros, 40, 141
+
+  Rhopoladon, 97
+
+  Rhynchocephala, 192
+
+  Roc, 36
+
+  Rochester, 136
+
+  Running limb, 38
+
+  Ryle, Bishop, 17
+
+
+S
+
+  Sacrum, 87, 88
+
+  St. George, 15
+
+  St. Ives, 156
+
+  Sarcorhamphus, 102
+
+  Saurians, 27
+
+  Saurischia, 190, 195, 198, 199
+
+  Sauromorpha, 191, 192
+
+  Sauropsida, 188
+
+  Sauropterygia, 192
+
+  Scaphognathus, 64, 85, 140, 152, 192, 212
+
+  _Scaphognathus crassirostris_, 73-5, 83
+
+  Scapular arch, 111, 113
+
+  Scelidosaurus, 135
+
+  Sclerotic circle, 65
+
+  Seals, 41
+
+  Sedgwick, Professor Adam, v, 46
+
+  Shillington, 77
+
+  Shoebill, 67
+
+  Shoe-shaped prepubic bones, 204, 205
+
+  Short-tailed pterodactyles, 165, 193
+
+  Shoulder-girdle, 107, 111, 114, 115, 183
+
+  Siberia, 141
+
+  Simultaneous origin of characters, 214, 224
+
+  Skin covering, 40, 41, 58, 139, 140
+
+  Skulls, 68
+
+  Sloth, 112
+
+  Snipe, 47, 68
+
+  Solenhofen Slate, 28, 32, 88, 153, 156
+
+  S�mmerring, 29
+
+  South African reptiles, 188, 208, 216
+
+  Spotted fly-catcher, 47
+
+  Squamosal bone, 12, 13
+
+  Sternal ribs, 110
+
+  Sternum, 107, 158
+
+  Stonesfield Slate, 33, 88, 153
+
+  Structures common to reptiles, 224
+
+  Stuttgart Museum, 32, 172, 203
+
+  Swanage, 172
+
+  Swan, neck of, 80, 113
+
+  Swift, 50
+
+  Swimming limb, 38
+
+  Synotus, 25
+
+  Syrinx, 48
+
+
+T
+
+  Tail, description of, 90;
+    in Cretaceous Pterodactyles, 193
+    -- long, 156;
+    short, 166;
+    in Dimorphodon, 145;
+    in Ornithocheirus, 179
+
+  Tanystrophoeus, long vertebr� in, 79
+
+  Tarsal bones, 102, 207
+
+  Tarso-metatarsus, 128
+
+  Teeth, 73, 137, 138;
+    in porpoise, 40
+
+  Temperature of blood, 56
+
+  Temporal arches, 68
+
+  -- bone, 12
+
+  -- fossa, 67
+
+  Teredo, 137
+
+  Texas fossils, 216
+
+  Thecospondylus, 209
+
+  Theriodont pelvis, 97
+
+  -- reptiles, 75;
+    of Russia, 96, 97;
+    of South Africa, 96, 117
+
+  Theropsida, 188
+
+  Thigh bone, 100, 206, 211
+
+  Three claws, 146, 197
+
+  Tibia, 102, 195;
+    in Iguanodon, 207
+
+  Toothless mammals, 40
+
+  -- pterodactyles, 138, 181;
+    beak of pterodactyles, 150
+
+  Transition from reptiles to birds, 211
+
+  Tree frogs, 21
+
+  Trias dinosaurs, 199
+
+  Triceratops, pelvis of, 204
+
+  Trout, 139;
+    of New Zealand, 228
+
+  Tuatera, 13
+
+  T�bingen Museum, 32
+
+  Tundras, 141
+
+  Tunny, 57
+
+  Turtles, neck bones, 79
+
+
+U
+
+  Ulna, description of, 119
+
+  Uncinate process of ribs, 85
+
+  Unlimited time, 228
+
+  Upper arm bone, 117
+
+  -- Greensand, remains in, 136
+
+  -- Lias of Whitby, 147
+
+  -- Oolites, 185, 195
+
+
+V
+
+  Variation of bones in mammals, 38
+
+  -- in Pterodactyles, 229
+
+  Variation of bones in vertebr�, 225
+
+  Vertebr�, caudal, 89, 92, 203
+
+  -- cervical, 173, 179, 203
+
+  -- dorsal, 86
+
+  Vertebral articulation, 82, 224
+
+  -- column, 78
+
+  Vulture, neck vertebr� of, 80;
+    tibia and fibula of, 102
+
+  Vomer, 147
+
+  Vomerine bones, 72
+
+
+W
+
+  Wagler, 29
+
+  Wagner, Andreas, 30, 148, 231
+
+  Walker, J. F., 54
+
+  Wealden beds, Pterodactyles in, 55, 84;
+    bones in, 135, 136, 173
+
+  Weight of Pterodactyle, 106
+
+  Whinchat, 47
+
+  Whitby, 33, 135
+
+  Williston, Professor W. S., 75, 82, 92, 98, 105, 110
+
+  Willow-wren, 47
+
+  Wing finger, 116, 130, 133, 151, 178, 197
+
+  -- membrane, 32, 121, 140, and frontispiece
+
+  -- metacarpal, 123;
+    in Dimorphodon, 151;
+    in Ornithostoma, 184;
+    in bats, 131
+
+  Wings of Dragons, 16
+
+  Winkler, T. C., 231
+
+  Woodwardian Museum, 34
+
+  Wood-wren, 47
+
+  Wrist bones, 122
+
+  W�rtemberg, 33
+
+
+Y
+
+  Yale College Museum, 32
+
+  York Museum, 34, 176
+
+
+Z
+
+  Zittel, Karl von, 31, 157, 165, 231
+
+  Zygomatic arch, 67
+
+
+
+
+  PRINTED BY
+  WILLIAM BRENDON AND SON
+  PLYMOUTH
+
+
+
+
+
+End of the Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley
+
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+      The Project Gutenberg eBook of Dragons of the Air, by H. G. Seeley.
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+<pre>
+
+The Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Dragons of the Air
+       An Account of Extinct Flying Reptiles
+
+Author: H. G. Seeley
+
+Release Date: February 18, 2011 [EBook #35316]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK DRAGONS OF THE AIR ***
+
+
+
+
+Produced by Chris Curnow and the Online Distributed
+Proofreading Team at http://www.pgdp.net (This file was
+produced from images generously made available by The
+Internet Archive)
+
+
+
+
+
+
+</pre>
+
+
+
+
+<p>&nbsp;</p>
+<h2>DRAGONS OF THE AIR</h2>
+<p>&nbsp;</p>
+<p>&nbsp;</p>
+
+
+<hr style="width: 65%;" />
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_47" id="Fig_47"></a>
+<span class="caption">FIG. 47. &nbsp; RHAMPHORHYNCHUS PHYLLURUS<br /><br />
+SHOWING THE PRESERVATION OF THE WING MEMBRANES</span>
+<img src="images/i_005.jpg" width="1024" height="614" alt="FIG. 47. RHAMPHORHYNCHUS PHYLLURUS" title="FIG. 47. RHAMPHORHYNCHUS PHYLLURUS" />
+<span class="caption"><i>From the Lithographic slate of Eichst&auml;dt, Bavaria</i></span>
+<p style='text-align:right'><i>Frontispiece</i></p>
+</div>
+
+
+<hr style="width: 65%;" />
+<h1>DRAGONS OF THE AIR</h1>
+
+<h3>AN ACCOUNT OF<br />
+EXTINCT FLYING REPTILES</h3>
+
+<h5>BY</h5>
+
+<h2>H. G. SEELEY, F.R.S.</h2>
+
+<h5>PROFESSOR OF GEOLOGY IN KING'S COLLEGE, LONDON; LECTURER ON GEOLOGY<br />
+AND MINERALOGY IN THE ROYAL INDIAN ENGINEERING COLLEGE</h5>
+
+<h4>WITH EIGHTY ILLUSTRATIONS</h4>
+
+
+<div class='center'>
+<table border="0" cellpadding="0" cellspacing="0" summary="">
+<tr><td align='left'>"I AM A BROTHER OF DRAGONS"</td></tr>
+<tr><td align='left'></td><td align='left'><i>Job</i> xxx. 29</td></tr>
+</table></div>
+
+<h4>NEW YORK: D. APPLETON &amp; CO.<br />
+LONDON: METHUEN &amp; CO.<br />
+<small>1901</small></h4>
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'>[Pg v]</span></p>
+<h2>PREFACE</h2>
+
+
+<p>I was a student of law at a time when Sir
+Richard Owen was lecturing on Extinct Fossil
+Reptiles. The skill of the great master, who built
+bones together as a child builds with a box of
+bricks, taught me that the laws which determine the
+forms of animals were less understood at that time
+than the laws which govern the relations of men in
+their country. The laws of Nature promised a better
+return of new knowledge for reasonable study. A
+lecture on Flying Reptiles determined me to attempt
+to fathom the mysteries which gave new types of life
+to the Earth and afterwards took them away.</p>
+
+<p>Thus I became the very humble servant of the
+Dragons of the Air. Knowing but little about them
+I went to Cambridge, and for ten years worked with
+the Professor of Geology, the late Rev. Adam Sedgwick,
+<small>LL.D., F.R.S.</small>, in gathering their bones from the
+so-called Cambridge Coprolite bed, the Cambridge
+Greensand. The bones came in thousands, battered
+and broken, but instructive as better materials might
+<span class='pagenum'>[Pg vi]</span>
+not have been. My rooms became filled with remains
+of existing birds, lizards, and mammals, which threw
+light on the astonishing collection of old bones which
+I assisted in bringing together for the University.</p>
+
+<p>In time I had something to say about Flying
+Animals which was new. The story was told in
+the theatre of the Royal Institution, in a series
+of lectures. Some of them were repeated in several
+English towns. There was still much to learn of
+foreign forms of flying animals; but at last, with
+the aid of the Government grant administered by the
+Royal Society, and the chiefs of the great Continental
+museums, I saw all the specimens in Europe.</p>
+
+<p>So I have again written out my lectures, with the
+aid of the latest discoveries, and the story of animal
+structure has lost nothing in interest as a twice-told
+tale. It still presents in epitome the story of life on
+the Earth. He who understands whence the Flying
+Reptiles came, how they endured, and disappeared
+from the Earth, has solved some of the greatest
+mysteries of life. I have only contributed something
+towards solving the problems.</p>
+
+<p>In telling my story, chiefly of facts in Nature, an
+attempt is made to show how a naturalist does his
+work, in the hope that perhaps a few readers will find
+happiness in following the workings of the laws of
+life. Such an illumination has proved to many
+worth seeking, a solid return for labour, which is
+<span class='pagenum'>[Pg vii]</span>
+not to be marketed on the Exchange, but may be
+taken freely without exhausting the treasury of
+Nature's truths. Such outlines of knowledge as
+here are offered to a larger public, may also, I
+believe, be acceptable to students of science and
+scientific men.</p>
+
+<p>The drawings given in illustration of the text have
+been made for me by Miss E. B. Seeley.</p>
+
+<p style='text-align: right'>H. G. S.</p>
+
+<p><span class="smcap">Kensington</span>, <i>May, 1901</i></p>
+
+<p><span class='pagenum'>[Pg viii]</span></p>
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'>[Pg ix]</span></p>
+<h2>CONTENTS</h2>
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align='right'></td><td align='right'><small>PAGE</small></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_I"><b>CHAPTER I.</b></a></td></tr>
+<tr><td align='left'>FLYING REPTILES</td><td align='right'><a href="#Page_1">1</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_II"><b>CHAPTER II.</b></a></td></tr>
+<tr><td align='left'>HOW A REPTILE IS KNOWN</td><td align='right'><a href="#Page_4">4</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_III"><b>CHAPTER III.</b></a></td></tr>
+<tr><td align='left'>A REPTILE IS KNOWN BY ITS BONES</td><td align='right'><a href="#Page_11">11</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_IV"><b>CHAPTER IV.</b></a></td></tr>
+<tr><td align='left'>ANIMALS WHICH FLY</td><td align='right'><a href="#Page_15">15</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_V"><b>CHAPTER V.</b></a></td></tr>
+<tr><td align='left'>DISCOVERY OF THE PTERODACTYLE</td><td align='right'><a href="#Page_27">27</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_VI"><b>CHAPTER VI.</b></a></td></tr>
+<tr><td align='left'>HOW ANIMALS ARE INTERPRETED BY THEIR BONES</td><td align='right'><a href="#Page_37">37</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_VII"><b>CHAPTER VII.</b></a></td></tr>
+<tr><td align='left'>INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS</td><td align='right'><a href="#Page_45">45</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_VIII"><b>CHAPTER VIII.</b></a></td></tr>
+<tr><td align='left'>THE PLAN OF THE SKELETON</td><td align='right'><a href="#Page_58">58</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_IX"><b>CHAPTER IX.</b></a></td></tr>
+<tr><td align='left'>THE BACKBONE, OR VERTEBRAL COLUMN</td><td align='right'><a href="#Page_78">78</a><span class='pagenum'>[Pg x]</span></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_X"><b>CHAPTER X.</b></a></td></tr>
+<tr><td align='left'>THE HIP-GIRDLE AND HIND LIMB</td><td align='right'><a href="#Page_93">93</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XI"><b>CHAPTER XI.</b></a></td></tr>
+<tr><td align='left'>SHOULDER-GIRDLE AND FORE LIMB</td><td align='right'><a href="#Page_107">107</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XII"><b>CHAPTER XII.</b></a></td></tr>
+<tr><td align='left'>EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS</td><td align='right'><a href="#Page_134">134</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XIII"><b>CHAPTER XIII.</b></a></td></tr>
+<tr><td align='left'>ANCIENT ORNITHOSAURS FROM THE LIAS</td><td align='right'><a href="#Page_143">143</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XIV"><b>CHAPTER XIV.</b></a></td></tr>
+<tr><td align='left'>ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS</td><td align='right'><a href="#Page_153">153</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XV"><b>CHAPTER XV.</b></a></td></tr>
+<tr><td align='left'>ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS</td><td align='right'><a href="#Page_172">172</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XVI"><b>CHAPTER XVI.</b></a></td></tr>
+<tr><td align='left'>CLASSIFICATION OF THE ORNITHOSAURIA</td><td align='right'><a href="#Page_187">187</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XVII"><b>CHAPTER XVII.</b></a></td></tr>
+<tr><td align='left'>FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM</td><td align='right'><a href="#Page_196">196</a></td></tr>
+<tr><td align='center' colspan='2'><a href="#CHAPTER_XVIII"><b>CHAPTER XVIII.</b></a></td></tr>
+<tr><td align='left'>HOW PTERODACTYLES MAY HAVE ORIGINATED</td><td align='right'><a href="#Page_213">213</a></td></tr>
+<tr><td align='center' colspan='2'>&nbsp;</td></tr>
+<tr><td align='left'><a href="#APPENDIX">APPENDIX</a></td><td align='right'><a href="#Page_231">231</a></td></tr>
+<tr><td align='center' colspan='2'>&nbsp;</td></tr>
+<tr><td align='left'><a href="#INDEX">INDEX</a></td><td align='right'><a href="#Page_233">233</a></td></tr>
+</table></div>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'>[Pg xi]</span></p>
+<h2>LIST OF ILLUSTRATIONS</h2>
+
+
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align='right'><small>FIG.</small></td><td align='right'></td><td align='right'><small>PAGE</small></td></tr>
+<tr><td align='right'><a href="#Fig_47">47.</a></td><td align='left'>Wings of Rhamphorhynchus</td><td align='right'><i>Frontispiece</i></td></tr>
+<tr><td align='right'><a href="#Fig_1">1.</a></td><td align='left'>Lung of the lung-fish Ceratodus</td><td align='right'><a href="#Page_5">5</a></td></tr>
+<tr><td align='right'><a href="#Fig_2">2.</a></td><td align='left'>Attachment of the lower jaw in a Mammal and in a Pterodactyle</td><td align='right'><a href="#Page_12">12</a></td></tr>
+<tr><td align='right'><a href="#Fig_3">3.</a></td><td align='left'>Chald&aelig;an Dragon</td><td align='right'><a href="#Page_15">15</a></td></tr>
+<tr><td align='right'><a href="#Fig_4">4.</a></td><td align='left'>Winged human figure from the Temple of Ephesus</td><td align='right'><a href="#Page_16">16</a></td></tr>
+<tr><td align='right'><a href="#Fig_5">5.</a></td><td align='left'>Flying fish Exoc&#339;tus</td><td align='right'><a href="#Page_18">18</a></td></tr>
+<tr><td align='right'><a href="#Fig_6">6.</a></td><td align='left'>Flying Frog</td><td align='right'><a href="#Page_19">19</a></td></tr>
+<tr><td align='right'><a href="#Fig_7">7.</a></td><td align='left'>Flying Lizard (Draco)</td><td align='right'><a href="#Page_20">20</a></td></tr>
+<tr><td align='right'><a href="#Fig_8">8.</a></td><td align='left'>Birds in flight</td><td align='right'><a href="#Page_22">22</a></td></tr>
+<tr><td align='right'><a href="#Fig_9">9.</a></td><td align='left'>Flying Squirrel (Pteromys)</td><td align='right'><a href="#Page_24">24</a></td></tr>
+<tr><td align='right'><a href="#Fig_10">10.</a></td><td align='left'>Bats, flying and walking</td><td align='right'><a href="#Page_25">25</a></td></tr>
+<tr><td align='right'><a href="#Fig_11">11.</a></td><td align='left'>Skeleton of <i>Pterodactylus longirostris</i></td><td align='right'><a href="#Page_28">28</a></td></tr>
+<tr><td align='right'><a href="#Fig_12">12.</a></td><td align='left'>The skeleton restored</td><td align='right'><a href="#Page_29">29</a></td></tr>
+<tr><td align='right'><a href="#Fig_13">13.</a></td><td align='left'>The animal form restored</td><td align='right'><a href="#Page_30">30</a></td></tr>
+<tr><td align='right'><a href="#Fig_14">14.</a></td><td align='left'>Fore limbs in four types of mammals</td><td align='right'><a href="#Page_38">38</a></td></tr>
+<tr><td align='right'><a href="#Fig_15">15.</a></td><td align='left'>Pneumatic foramen in Pterodactyle bone</td><td align='right'><a href="#Page_46">46</a></td></tr>
+<tr><td align='right'><a href="#Fig_16">16.</a></td><td align='left'>Lungs of the bird Apteryx</td><td align='right'><a href="#Page_48">48</a></td></tr>
+<tr><td align='right'><a href="#Fig_17">17.</a></td><td align='left'>Air cells in the body of an Ostrich</td><td align='right'><a href="#Page_49">49</a></td></tr>
+<tr><td align='right'><a href="#Fig_18">18.</a></td><td align='left'>Lung of a Chameleon</td><td align='right'><a href="#Page_51">51</a></td></tr>
+<tr><td align='right'><a href="#Fig_19">19.</a></td><td align='left'>Brain in Pterodactyle, Mammal, Bird, and Reptiles</td><td align='right'><a href="#Page_53">53</a></td></tr>
+<tr><td align='right'><a href="#Fig_20">20.</a></td><td align='left'>Skull of Kingfisher and Rhamphorhynchus</td><td align='right'><a href="#Page_63">63</a></td></tr>
+<tr><td align='right'><a href="#Fig_21">21.</a></td><td align='left'>Skull of Heron and Rhamphorhynchus</td><td align='right'><a href="#Page_65">65</a></td></tr>
+<tr><td align='right'><a href="#Fig_22">22.</a></td><td align='left'>Palate of Macrocercus and ? Campylognathus</td><td align='right'><a href="#Page_71">71</a></td></tr>
+<tr><td align='right'><a href="#Fig_23">23.</a></td><td align='left'>Lower jaw of Echidna and Ornithostoma</td><td align='right'><a href="#Page_76">76</a></td></tr>
+<tr><td align='right'><a href="#Fig_24">24.</a></td><td align='left'>First two neck vertebr&aelig; of Ornithocheirus</td><td align='right'><a href="#Page_81">81</a><span class='pagenum'>[Pg xii]</span></td></tr>
+<tr><td align='right'><a href="#Fig_25">25.</a></td><td align='left'>Middle neck vertebr&aelig; of Ornithocheirus</td><td align='right'><a href="#Page_83">83</a></td></tr>
+<tr><td align='right'><a href="#Fig_26">26.</a></td><td align='left'>Back vertebra of Ornithocheirus and Crocodile</td><td align='right'><a href="#Page_86">86</a></td></tr>
+<tr><td align='right'><a href="#Fig_27">27.</a></td><td align='left'>Sacrum, with hip bones, of Rhamphorhynchus</td><td align='right'><a href="#Page_88">88</a></td></tr>
+<tr><td align='right'><a href="#Fig_28">28.</a></td><td align='left'>Extremity of tail of <i>Rhamphorhynchus phyllurus</i></td><td align='right'><a href="#Page_91">91</a></td></tr>
+<tr><td align='right'><a href="#Fig_29">29.</a></td><td align='left'>Hip-girdle bones in Apteryx and Rhamphorhynchus</td><td align='right'><a href="#Page_95">95</a></td></tr>
+<tr><td align='right'><a href="#Fig_30">30.</a></td><td align='left'>Pelvis with prepubic bone in Pterodactylus</td><td align='right'><a href="#Page_96">96</a></td></tr>
+<tr><td align='right'><a href="#Fig_31">31.</a></td><td align='left'>Pelvis with prepubic bones in Rhamphorhynchus</td><td align='right'><a href="#Page_97">97</a></td></tr>
+<tr><td align='right'><a href="#Fig_32">32.</a></td><td align='left'>Pelvis of an Alligator seen from below</td><td align='right'><a href="#Page_98">98</a></td></tr>
+<tr><td align='right'><a href="#Fig_33">33.</a></td><td align='left'>Femora: Echidna, Ornithocheirus, Ursus</td><td align='right'><a href="#Page_100">100</a></td></tr>
+<tr><td align='right'><a href="#Fig_34">34.</a></td><td align='left'>Tibia and fibula: Dimorphodon and Vulture</td><td align='right'><a href="#Page_102">102</a></td></tr>
+<tr><td align='right'><a href="#Fig_35">35.</a></td><td align='left'>Metatarsus and digits in three Pterodactyles</td><td align='right'><a href="#Page_104">104</a></td></tr>
+<tr><td align='right'><a href="#Fig_36">36.</a></td><td align='left'>Sternum in Cormorant and Rhamphorhynchus</td><td align='right'><a href="#Page_108">108</a></td></tr>
+<tr><td align='right'><a href="#Fig_37">37.</a></td><td align='left'>Sternum in Ornithocheirus</td><td align='right'><a href="#Page_109">109</a></td></tr>
+<tr><td align='right'><a href="#Fig_38">38.</a></td><td align='left'>Shoulder-girdle bones in a bird and three Pterodactyles</td><td align='right'><a href="#Page_113">113</a></td></tr>
+<tr><td align='right'><a href="#Fig_39">39.</a></td><td align='left'>The Notarium from the back of Ornithocheirus</td><td align='right'><a href="#Page_115">115</a></td></tr>
+<tr><td align='right'><a href="#Fig_40">40.</a></td><td align='left'>The shoulder-girdle of Ornithocheirus</td><td align='right'><a href="#Page_115">115</a></td></tr>
+<tr><td align='right'><a href="#Fig_41">41.</a></td><td align='left'>Humerus of Pigeon and Ornithocheirus</td><td align='right'><a href="#Page_119">119</a></td></tr>
+<tr><td align='right'><a href="#Fig_42">42.</a></td><td align='left'>Fore-arm of Golden Eagle and Dimorphodon</td><td align='right'><a href="#Page_120">120</a></td></tr>
+<tr><td align='right'><a href="#Fig_43">43.</a></td><td align='left'>Wrist bones of Ornithocheirus</td><td align='right'><a href="#Page_124">124</a></td></tr>
+<tr><td align='right'><a href="#Fig_44">44.</a></td><td align='left'>Clawed digits of the hand in two Pterodactyles</td><td align='right'><a href="#Page_125">125</a></td></tr>
+<tr><td align='right'><a href="#Fig_45">45.</a></td><td align='left'>Claw from the hand of Ornithocheirus</td><td align='right'><a href="#Page_129">129</a></td></tr>
+<tr><td align='right'><a href="#Fig_46">46.</a></td><td align='left'>The hand in Arch&aelig;opteryx and the Ostrich</td><td align='right'><a href="#Page_130">130</a></td></tr>
+<tr><td align='right'><a href="#Fig_48">48.</a></td><td align='left'>Slab of Lias with bones of Dimorphodon</td><td align='right'><i>To face page</i> <a href="#Page_143">143</a></td></tr>
+<tr><td align='right'><a href="#Fig_49">49.</a></td><td align='left'>Dimorphodon (restored form) at rest</td><td align='right'><a href="#Page_144">144</a></td></tr>
+<tr><td align='right'><a href="#Fig_50">50.</a></td><td align='left'>Dimorphodon (restored form of the animal)</td><td align='right'><i>To face page</i> <a href="#Page_145">145</a></td></tr>
+<tr><td align='right'><a href="#Fig_51">51.</a></td><td align='left'>Dimorphodon skeleton, walking as a quadruped</td><td align='right'><i>To face page</i> <a href="#Page_146">146</a></td></tr>
+<tr><td align='right'><a href="#Fig_52">52.</a></td><td align='left'>Dimorphodon skeleton as a biped</td><td align='right'><i>To face page</i> <a href="#Page_147">147</a></td></tr>
+<tr><td align='right'><a href="#Fig_53">53.</a></td><td align='left'>Lower jaw of Dorygnathus</td><td align='right'><a href="#Page_149">149</a></td></tr>
+<tr><td align='right'><a href="#Fig_54">54.</a></td><td align='left'>Dimorphodon (wing membranes spread for flight)</td><td align='right'><i>To face page</i> <a href="#Page_150">150</a></td></tr>
+<tr><td align='right'><a href="#Fig_55">55.</a></td><td align='left'>Pelvis of Dimorphodon</td><td align='right'><a href="#Page_151">151</a></td></tr>
+<tr><td align='right'><a href="#Fig_56">56.</a></td><td align='left'>Rhamphorhynchus skeleton (restored)</td><td align='right'><a href="#Page_161">161</a></td></tr>
+<tr><td align='right'><a href="#Fig_57">57.</a></td><td align='left'>Scaphognathus (restoration of 1875)</td><td align='right'><a href="#Page_163">163</a></td></tr>
+<tr><td align='right'><a href="#Fig_58">58.</a></td><td align='left'>Six restorations of Ornithosaurs</td><td align='right'><a href="#Page_164">164</a></td></tr>
+<tr><td align='right'><a href="#Fig_59">59.</a></td><td align='left'>Ptenodracon skeleton (restored)</td><td align='right'><a href="#Page_167">167</a></td></tr>
+<tr><td align='right'><a href="#Fig_60">60.</a></td><td align='left'><i>Cycnorhamphus suevicus</i> slab with bones</td><td align='right'><i>To face page</i> <a href="#Page_168">168</a></td></tr>
+<tr><td align='right'><a href="#Fig_61">61.</a></td><td align='left'><i>Cycnorhamphus suevicus</i> (form of the animal)</td><td align='right'><i>To face page</i> <a href="#Page_169">169</a></td></tr>
+<tr><td align='right'><a href="#Fig_62">62.</a></td><td align='left'><i>Cycnorhamphus suevicus</i> skeleton (restored)</td><td align='right'><a href="#Page_170">170</a><span class='pagenum'>[Pg xiii]</span></td></tr>
+<tr><td align='right'><a href="#Fig_63">63.</a></td><td align='left'><i>Cycnorhamphus Fraasi</i> (restored skeleton form of the animal)</td><td align='right'><i>To face page</i> <a href="#Page_170">170</a></td></tr>
+<tr><td align='right'><a href="#Fig_64">64.</a></td><td align='left'><i>Cycnorhamphus Fraasi</i> (restoration of the form of the body)</td><td align='right'><i>To face page</i> <a href="#Page_171">171</a></td></tr>
+<tr><td align='right'><a href="#Fig_65">65.</a></td><td align='left'>Neck vertebra of Doratorhynchus from the Purbeck</td><td align='right'><a href="#Page_173">173</a></td></tr>
+<tr><td align='right'><a href="#Fig_66">66.</a></td><td align='left'>Neck bone of Ornithodesmus from the Wealden</td><td align='right'><a href="#Page_173">173</a></td></tr>
+<tr><td align='right'><a href="#Fig_67">67.</a></td><td align='left'>Sternum of Ornithodesmus, seen from the front</td><td align='right'><a href="#Page_175">175</a></td></tr>
+<tr><td align='right'><a href="#Fig_68">68.</a></td><td align='left'>Sternum of Ornithodesmus, side view, showing the keel</td><td align='right'><a href="#Page_175">175</a></td></tr>
+<tr><td align='right'><a href="#Fig_69">69.</a></td><td align='left'>Diagram of known parts of skull of Ornithocheirus</td><td align='right'><a href="#Page_177">177</a></td></tr>
+<tr><td align='right'><a href="#Fig_70">70.</a></td><td align='left'>Neck bone of Ornithocheirus</td><td align='right'><a href="#Page_179">179</a></td></tr>
+<tr><td align='right'><a href="#Fig_71">71.</a></td><td align='left'>Jaws of Ornithocheirus from the Chalk</td><td align='right'><a href="#Page_180">180</a></td></tr>
+<tr><td align='right'><a href="#Fig_72">72.</a></td><td align='left'>Palate of the English Toothless Pterodactyle</td><td align='right'><a href="#Page_181">181</a></td></tr>
+<tr><td align='right'><a href="#Fig_73">73.</a></td><td align='left'>Two views of the skull of Ornithostoma (Pteranodon)</td><td align='right'><a href="#Page_182">182</a></td></tr>
+<tr><td align='right'><a href="#Fig_74">74.</a></td><td align='left'>Skeleton of Ornithostoma</td><td align='right'><a href="#Page_183">183</a></td></tr>
+<tr><td align='right'><a href="#Fig_75">75.</a></td><td align='left'>Comparison of six skulls of Ornithosaurs</td><td align='right'><a href="#Page_192">192</a></td></tr>
+<tr><td align='right'><a href="#Fig_76">76.</a></td><td align='left'>Pelvis of Ornithostoma</td><td align='right'><a href="#Page_195">195</a></td></tr>
+<tr><td align='right'><a href="#Fig_77">77.</a></td><td align='left'>Skull of Anchisaurus and Dimorphodon</td><td align='right'><a href="#Page_199">199</a></td></tr>
+<tr><td align='right'><a href="#Fig_78">78.</a></td><td align='left'>Skull of Ornithosuchus and Dimorphodon</td><td align='right'><a href="#Page_201">201</a></td></tr>
+<tr><td align='right'><a href="#Fig_79">79.</a></td><td align='left'>The pelvis in Ornithosaur and Dinosaur</td><td align='right'><a href="#Page_204">204</a></td></tr>
+<tr><td align='right'><a href="#Fig_80">80.</a></td><td align='left'>The prepubic bones in Dimorphodon and Iguanodon</td><td align='right'><a href="#Page_206">206</a></td></tr>
+</table></div>
+
+<div class="blockquot"><p class="noidt">These figures are greatly reduced in size, and when two or more bones are shown
+in the same figure all are brought to the same size to facilitate the comparison.</p></div>
+
+<p><span class='pagenum'>[Pg xiv]</span></p>
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_1" id="Page_1">[Pg 1]</a></span></p>
+<h1>DRAGONS OF THE AIR</h1>
+
+
+
+<hr style="width: 15%;" />
+<h2><a name="CHAPTER_I" id="CHAPTER_I"></a><small>CHAPTER I</small><br /><br />
+
+FLYING REPTILES</h2>
+
+
+<p>The history of life on the earth during the
+epochs of geological time unfolds no more
+wonderful discovery among types of animals which
+have become extinct than the family of fossils known
+as flying reptiles. Its coming into existence, its
+structure, and passing away from the living world
+are among the great mysteries of Nature.</p>
+
+<p>The animals are astonishing in their plan of construction.
+In aspect they are unlike birds and beasts
+which, in this age, hover over land and sea. They
+gather into themselves in the body of a single individual,
+structures which, at the present day, are
+among the most distinctive characters of certain
+mammals, birds, and reptiles.</p>
+
+<p>The name "flying reptile" expresses this anomaly.
+Its invention is due to the genius of the great French
+naturalist Cuvier, who was the first to realise that this
+extinct animal, entombed in slabs of stone, is one of
+the wonders of the world.</p>
+
+<p>The word "reptile" has impressed the imagination
+with unpleasant sound, even when the habits of the<span class='pagenum'><a name="Page_2" id="Page_2">[Pg 2]</a></span>
+animals it indicates are unknown. It is familiarly
+associated with life which is reputed venomous, and
+is creeping and cold. Its common type, the serpent,
+in many parts of the world takes a yearly toll of
+victims from man and beast, and has become the
+representative of silent, active strength, dreaded craft,
+and danger.</p>
+
+<p>Science uses the word "reptile" in a more exact
+way, to define the assemblage of cold-blooded animals
+which in familiar description are separately named
+serpents, lizards, turtles, hatteria, and crocodiles.</p>
+
+<p>Turtles and the rest of them survive from great
+geological antiquity. They present from age to age
+diversity of aspect and habit, and in unexpected
+differences of outward proportion of the body show
+how the laws of life have preserved each animal type.
+For the vital organs which constitute each animal
+a reptile, and the distinctive bony structures with
+which they are associated, remain unaffected, or but
+little modified, by the animal's external change in
+appearance.</p>
+
+<p>The creeping reptile is commonly imagined as the
+antithesis of the bird. For the bird overcomes the
+forces that hold even man to the earth, and enjoys
+exalted aerial conditions of life. Therefore the marvel
+is shared equally by learned and unlearned, that the
+power of flight should have been an endowment of
+animals sprung from the breed of serpents, or crocodiles,
+enabling them to move through the air as
+though they too were of a heaven-born race. The
+wonder would not be lessened if the animal were
+a degraded representative of a nobler type, or if
+it should be demonstrated that even beasts have
+advanced in the battle of life. The winged reptile,<span class='pagenum'><a name="Page_3" id="Page_3">[Pg 3]</a></span>
+when compared with a bird, is not less astounding
+than the poetic conceptions in Milton's <i>Paradise
+Lost</i> of degradation which overtakes life that once
+was amongst the highest. And on the other hand,
+from the point of view of the teaching of Darwin
+in the theories of modern science, we are led to ask
+whether a flying reptile may not be evidence of the
+physical exaltation which raises animals in the scale
+of organisation. The dominance upon the earth of
+flying reptiles during the great middle period of
+geological history will long engage the interest
+of those who can realise the complexity of its
+structure, or care to unravel the meaning of the
+procession of animal forms in successive geological
+ages which preceded the coming of man.</p>
+
+<p>The outer vesture of an animal counts for little in
+estimating the value of ties which bind orders of
+animals together, which are included in the larger
+classes of life. The kindred relationship which makes
+the snake of the same class as the tortoise is determined
+by the soft vital organs&mdash;brain, heart, lungs&mdash;which
+are the essentials of an animal's existence and
+control its way of life. The wonder which science
+weaves into the meaning of the word "reptile," "bird,"
+or "mammal," is partly in exhibiting minor changes
+of character in those organs and other soft parts, but
+far more in showing that while they endure unchanged,
+the hard parts of the skeleton are modified
+in many ways. For the bones of the reptile orders
+stretch their affinities in one direction towards the
+skeletons of salamanders and fishes; and extend
+them also at the same time in other directions,
+towards birds and mammals. This mystery we may
+hope to partly unravel.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_4" id="Page_4">[Pg 4]</a></span></p>
+<h2><a name="CHAPTER_II" id="CHAPTER_II"></a><small>CHAPTER II</small><br /><br />
+
+HOW A REPTILE IS KNOWN</h2>
+
+<h4>DEFINITION OF REPTILES BY THEIR
+VITAL ORGANS</h4>
+
+
+<p>The relations of reptiles to other animals may be
+stated so as to make evident the characters and
+affinities which bind them together. Early in the
+nineteenth century naturalists included with the Reptilia
+the tribe of salamanders and frogs which are
+named Amphibia. The two groups have been separated
+from each other because the young of Amphibia
+pass through a tadpole stage of development. They
+then breathe by gills, like fishes, taking oxygen from
+the air which is suspended in water, before lungs are
+acquired which afterwards enable the animals to take
+oxygen directly from the air. The amphibian sometimes
+sheds the gills, and leaves the water to live on
+land. Sometimes gills and lungs are retained through
+life in the same individual. This amphibian condition
+of lung and gill being present at the same
+time is paralleled by a few fishes which still exist,
+like the Australian <i>Ceratodus</i>, the lung-fish, an ancient
+type of fish which belongs to early days in geological
+time.</p>
+
+<p>This metamorphosis has been held to separate the<span class='pagenum'><a name="Page_5" id="Page_5">[Pg 5]</a></span>
+amphibian type from the reptile because no existing
+reptile develops gills or undergoes a metamorphosis.
+Yet the character may not be more important
+as a ground for classification
+than the community of gills and lungs
+in the fish and amphibian is ground for
+putting them together in one natural
+group. For although no gills are found
+in reptiles, birds, or mammals, the
+embryo of each in an early stage of
+development appears to possess gill-arches,
+and gill-clefts between them,
+through which gills might have been
+developed, even in the higher vertebrates,
+if the conditions of life had
+been favourable to such modification
+of structure. In their bones Reptiles
+and Amphibia have much in common.
+Nearly all true reptiles lay eggs, which
+are defined like those of birds by comparatively
+large size, and are contained
+in shells. This condition is not usual
+in amphibians or fishes. When hatched
+the young reptile is completely formed,
+the image of its parent, and has no need
+to grow a covering to its skin like some
+birds, or shed its tail like some tadpoles.
+The reptile is like the bird in freedom
+from important changes of form after the egg is
+hatched; and the only structure shed by both is the
+little horn upon the nose, with which the embryo
+breaks the shell and emerges a reptile or a bird,
+growing to maturity with small subsequent variations
+in the proportions of the body.</p>
+
+
+<div class="figcenter" style="width: 157px;">
+<a name="Fig_1" id="Fig_1"></a>
+<span class="caption">FIG. 1 &nbsp; LUNG OF THE FISH CERATODUS</span>
+<img src="images/i_022.jpg" width="157" height="640" alt="FIG. 1 LUNG OF THE FISH CERATODUS" title="FIG. 1" />
+</div>
+<p class="center">Partly laid open to show its chambered structure<br />
+(After G&uuml;nther)</p>
+
+
+<p><span class='pagenum'><a name="Page_6" id="Page_6">[Pg 6]</a></span></p>
+
+<h4>THE REPTILE SKIN</h4>
+
+<p>Between one class of animals and another the
+differences in the condition of the skin are more
+or less distinctive. In a few amphibians there are
+some bones in the skin on the under side of the
+body, though the skin is usually naked, and in frogs
+is said to transmit air to the blood, so as to exercise
+a respiratory function of a minor kind. This naked
+condition, so unlike the armoured skin of the true
+Reptilia, appears to have been paralleled by a number
+of extinct groups of fossils of the Secondary rocks,
+such as Ichthyosaurs and Plesiosaurs, which were
+aquatic, and probably also by some Dinosauria, which
+were terrestrial.</p>
+
+<p>Living reptiles are usually defended with some
+kind of protection to the skin. Among snakes and
+lizards the skin has commonly a covering of overlapping
+scales, usually of horny or bony texture.
+The tortoise and turtle tribe shut up the animal in a
+true box of bone, which is cased with an armour of
+horny plates. Crocodiles have a thick skin embedding
+a less continuous coat of mail. Thus the
+skin of a reptile does not at first suggest anything
+which might become an organ of flight; and its
+dermal appendages, or scales, may seem further removed
+from the feathers which ensure flying powers
+to the bird than from the naked skin of a frog.</p>
+
+
+<h4>THE REPTILE BRAIN</h4>
+
+<p>Although the mode of development of the young
+and the covering of the skin are conspicuous among
+important characters by which animals are classified,
+the brain is an organ of some importance, although<span class='pagenum'><a name="Page_7" id="Page_7">[Pg 7]</a></span>
+of greater weight in the higher Vertebrata than in its
+lower groups. Reptiles have links in the mode of
+arrangement of the parts of their brains with fishes
+and amphibians. The regions of that organ are commonly
+arranged in pairs of nervous masses, known
+as (1) the olfactory lobes, (2) the cerebrum, behind
+which is the minute pineal body, followed by (3) the
+pair of optic lobes, and hindermost of all (4) the
+single mass termed the cerebellum. These parts of
+the brain are extended in longitudinal order, one
+behind the other in all three groups. The olfactory
+lobes of the brain in Fishes may be as large as
+the cerebrum; but among Reptiles and Amphibians
+they are relatively smaller, and they assume more of
+the condition found in mammals like the Hare or
+Mole, being altogether subordinate in size. And the
+cerebral masses begin to be wider and higher than
+the other parts of the brain, though they do not extend
+forward above the olfactory lobes, as is often seen in
+Mammals. In Crocodiles the cerebral hemispheres
+have a tendency to a broad circular form. Among
+Chelonian reptiles that region of the brain is more
+remarkable for height. Lizards and Ophidians both
+have this part of the brain somewhat pear-shaped,
+pointed in front, and elongated. The amphibian
+brain only differs from the lizard type in degree; and
+differences between lizards' and amphibian brains are
+less noticeable than between the other orders of
+reptiles. The reptilian brain is easily distinguished
+from that of all other animals by the position and
+proportions of its regions (see <a href="#Fig_19">Fig. 19, p. 53</a>).</p>
+
+<p>Birds have the parts of the brain formed and
+arranged in a way that is equally distinctive. The
+cerebral lobes are relatively large and convex, and<span class='pagenum'><a name="Page_8" id="Page_8">[Pg 8]</a></span>
+deserve the descriptive name "hemispheres." They
+are always smooth, as among the lower Mammals,
+and extend backward so as to abut against the hind
+brain, termed the cerebellum. This junction is
+brought about in a peculiar way. The cerebral
+hemispheres in a bird do not extend backward to
+override the optic lobes, and hide them, as occurs
+among adult mammals, but they extend back between
+the optic lobes, so as to force them apart and
+push them aside, downward and backward, till they
+extend laterally beyond the junction of the cerebrum
+with the cerebellum. The brain of a Bird is never
+reptilian; but in the young Mammal the brain has
+a very reptilian aspect, because both have their parts
+primarily arranged in a line. Therefore the brain
+appears to determine the boundary between bird
+and reptile exactly.</p>
+
+
+<h4>REPTILIAN BREATHING ORGANS</h4>
+
+<p>The breathing organs of Birds and Reptiles which
+are associated with these different types of brain are
+not quite the same. The Frog has a cellular lung
+which, in the details of the minute sacs which branch
+and cluster at the terminations of the tubes, is not
+unlike the condition in a Mammal. In a mammal
+respiration is aided by the bellows-like action of the
+muscles connected with the ribs, which encase the
+cavity where the lungs are placed, and this structure
+is absent in the Frog and its allies. The Frog, on the
+other hand, has to swallow air in much the same way
+as man swallows water. The air is similarly grasped
+by the muscles, and conveyed by them downward to
+the lungs. Therefore a Frog keeps its mouth shut,<span class='pagenum'><a name="Page_9" id="Page_9">[Pg 9]</a></span>
+and the animal dies from want of air if its mouth is
+open for a few minutes.</p>
+
+<p>Crocodiles commonly lie in the sun with their
+mouths widely open. The lungs in both Crocodiles
+and Turtles are moderately dense, traversed by great
+bronchial tubes, but do not differ essentially in plan
+from those of a Frog, though the great branches of
+the bronchial tubes are stronger, and the air chambers
+into which the lung is divided are somewhat smaller.
+The New Zealand Hatteria has the lungs of this
+cellular type, though rather resembling the amphibian
+than the Crocodile. The lungs during life in all
+these animals attain considerable size, the maximum
+dimensions being found in the terrestrial tortoises,
+which owe much of their elevated bulk to the dimensions
+of the air cells which form the lungs.</p>
+
+<p>The lungs of Serpents and Lizards are formed on
+a different plan. In both those groups of reptiles
+the dense cellular tissue is limited to the part of the
+lung which is nearest to the throat. This network
+of blood vessels and air cells extends about the
+principal bronchial tube much as in other animals,
+but as it extends backward the blood vessels become
+few until the <i>tubular</i> lung appears in its hinder part,
+as it extends down the body, almost as simple in
+structure as the air bladder of a fish. Among Serpents
+only one of these tubular lungs is commonly
+present, and the structure has a less efficient appearance
+as a breathing organ than the single lung of the
+fish <i>Ceratodus</i> (<a href="#Fig_1">Fig. 1</a>). The Chameleons are a group of
+lizards which differ in many ways from most of their
+nearest kindred, and the lungs, while conforming in
+general plan to the lizard type in being dense at the
+throat, and a tubular bladder in the body, give off<span class='pagenum'><a name="Page_10" id="Page_10">[Pg 10]</a></span>
+on both sides a number of short lateral branches
+like the fingers of a glove (<a href="#Fig_18">Fig. 18, p. 51</a>).</p>
+
+<p>Thus the breathing organs of reptiles present two
+or three distinct types which have caused Serpents
+and Lizards to be associated in one group by most
+naturalists who have studied their anatomy; while
+Crocodiles and Chelonians represent a type of lung
+which is quite different, and in those groups has
+much in common. These characters of the breathing
+organs contribute to separate the cold-blooded
+armoured reptiles from the warm-blooded birds
+clothed with feathers, as well as from the warm-blooded
+mammals which suckle their young; for both
+these higher groups have denser and more elastic
+spongy lung tissue.</p>
+
+<p>It will be seen hereafter that many birds in the
+most active development of their breathing organs
+substantially revert to the condition of the Serpent
+or Chameleon in a somewhat modified way. Because,
+instead of having one great bronchial tube expanded
+to form a vast reservoir of air which can be discharged
+from the lung in which the reptile has
+accumulated it, the bird has the lateral branches
+of the bronchial tubes prolonged so as to pierce the
+walls of the lung, when its covering membrane expands
+to form many air cells, which fill much of the
+cavity of the bird's body (see <a href="#Fig_16">Fig. 16</a>). Thus the bird
+appears to combine the characters of such a lung as
+that of a Crocodile, with a condition which has some
+analogy with the lung of a Chameleon. It is this link
+of structure of the breathing organs between reptiles
+and birds that constitutes one of the chief interests
+of flying reptiles, for they prove to have possessed
+air cells prolonged from the lungs, which extended
+into the bones.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_11" id="Page_11">[Pg 11]</a></span></p>
+<h2><a name="CHAPTER_III" id="CHAPTER_III"></a><small>CHAPTER III</small><br /><br />
+
+A REPTILE IS KNOWN BY ITS
+BONES</h2>
+
+
+<p>Such are a few illustrations of ways in which
+reptiles resemble other animals, and differ from
+them, in the organs by means of which the classification
+of animals is made. But such an idea is
+incomplete without noticing that the bony framework
+of the body associated with such vital organs also
+shows in its chief parts that reptiles are easily recognised
+by their bones. I will therefore briefly state
+how reptiles are defined in some regions of the
+skeleton, for in tracing the history of reptile life
+the bones are the principal remains of animals
+preserved in the rocks; and the soft organs which
+have perished can only be inferred to have been
+present from the persistence of durable characteristic
+parts of the skeleton, which are associated with those
+soft organs in animals which exist at the present day,
+and are unknown in other animals in which the
+skeleton is different.</p>
+
+
+<h4>THE HANG OF THE LOWER JAW</h4>
+
+<p>The manner in which the lower jaw is connected
+with the skull yields one of the most easily recog<span class='pagenum'><a name="Page_12" id="Page_12">[Pg 12]</a></span>nised
+differences between the great groups of vertebrate
+animals.</p>
+
+<p><i>In Mammals.</i>&mdash;In every mammal&mdash;such as the Dog
+or Sheep&mdash;the lower jaw, which is formed of one bone
+on each side, joins directly on to the head of the
+animal, and moves upon a bone of the skull which
+is named the temporal bone. This character is
+sufficient to prove, by the law of association of soft
+and hard parts of the body, that such an animal had
+warm blood and suckled its young.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_2" id="Fig_2"></a>
+<span class="caption">FIG. 2</span>
+<img src="images/i_029.jpg" width="640" height="191" alt="FIG. 2" title="FIG. 2" />
+<p class="center">Comparison to show the articulation with the lower jaw in a mammal and
+<i>Pterodactylus Kochi</i>.<br />
+The quadrate bone is lettered Q in this Pterodactyle, and comes between the skull and<br />
+the lower jaw like the quadrate bone in a bird and in lizards.</p>
+</div>
+
+
+<p><i>In Birds.</i>&mdash;In birds a great difference is found in
+this region of the head. The temporal bone, which
+it will be more convenient to name the squamosal
+bone, from its squamous or scale-like form, is still
+a part of the brain case, and assists in covering the
+brain itself, exactly as among mammals. But the
+lower jaw is now made up of five or six bones. And
+between the hindermost and the squamosal there is
+an intervening bar of bone, unknown among mammalia,
+which moves upon the skull by a joint, just as
+the lower jaw moves upon it. This movable bone
+unites with parts of the palate and the face, and is
+known as the quadrate bone. Its presence proves
+that the animal possessing it laid eggs, and if the<span class='pagenum'><a name="Page_13" id="Page_13">[Pg 13]</a></span>
+face bones join its outer border just above the lower
+jaw, it proves that the animal possessed hot blood.</p>
+
+<p><i>In Reptiles.</i>&mdash;All reptiles are also regarded as
+possessing the quadrate bone. But the squamosal
+bone with which it always unites is in less close
+union with the brain case, and never covers the brain
+itself. Serpents show an extreme divergence in this
+condition from birds, for the squamosal bone appears
+to be a loose external plate of bone which rests
+upon the compact brain case and gives attachment
+to the quadrate bone which is as free as in a bird.
+Among Lizards the quadrate bone is usually almost
+as free. In the other division of existing Reptilia,
+including Crocodiles, the New Zealand lizard-like
+reptile Hatteria, called Tuatera, and Turtles, the
+squamosal and quadrate bones are firmly united with
+the bones of the brain case, face, and palate, so that
+the quadrate bone has no movement; and the same
+condition appears in amphibians, such as Toads and
+Frogs. With these conditions of the quadrate bone
+are associated cold blood, terrestrial life, and young
+developed from eggs.</p>
+
+<p><i>In Fishes.</i>&mdash;Bony fishes, and all others in which
+separate bones build up the skull, differ from Reptiles
+and Birds much as those animals differ from
+Mammals. The union of the lower jaw with the
+skull becomes complicated by the presence of additional
+bones. The quadrate bone still forms a pulley
+articulation upon which the lower jaw works, but
+between it and the squamosal bone is the characteristic
+bone of the fish known as the hyomandibular,
+commonly connected with opercular bones and
+metapterygoid which intervene, and help to unite
+the quadrate with the brain case. In the Cartila<span class='pagenum'><a name="Page_14" id="Page_14">[Pg 14]</a></span>ginous
+fishes there is only one bone connecting the
+jaws with the skull on each side. This appears to
+prove that just as the structure of the arch of bones
+suspending the jaw may be complicated by the
+mysterious process called segmentation, which separates
+a bone into portions, so simplification and
+variation may result because the primitive divisions
+of the material cease to be made which exists before
+bones are formed.</p>
+
+<p>The principal regions of the skull and skeleton all
+vary in the chief groups of animals with backbones;
+so that the Reptile may be recognised among fossils,
+even in extinct groups of animals and occasionally
+restored from a fragment, to the aspect which characterised
+it while it lived.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_15" id="Page_15">[Pg 15]</a></span></p>
+<h2><a name="CHAPTER_IV" id="CHAPTER_IV"></a><small>CHAPTER IV</small><br /><br />
+
+ANIMALS WHICH FLY</h2>
+
+
+<p>The nature of a reptile is now sufficiently intelligible
+for something to be said concerning
+flight, and structures by means of which some animals
+lift themselves in the air. It is not without interest
+to remember that, from the earliest periods in human
+records, representations have been made of animals
+which were furnished with wings, yet walked upon
+four feet, and in their
+typical aspect have the
+head shaped like that of
+a bird. They are commonly
+named Dragons.</p>
+
+
+<h4>FLYING DRAGONS</h4>
+
+<div class="figcenter" style="width: 461px;">
+<a name="Fig_3" id="Fig_3"></a>
+<span class="caption">FIG. 3 &nbsp; From <i>The Battle between Bel and the Dragon</i></span>
+<img src="images/i_032.jpg" width="461" height="640" alt="FIG. 3" title="FIG. 3" />
+</div>
+
+<p>The effigy of the
+dragon survives to the
+present day in the figure
+over which St. George
+triumphs, on the reverse
+of the British sovereign.
+In the luxuriant imaginations
+of ancient Eastern
+peoples, dating back
+<span class='pagenum'><a name="Page_16" id="Page_16">[Pg 16]</a></span>
+to prehistoric ages, perhaps 5000 <small>B.C.</small>, the dragons
+present an astonishing constancy of form. In after-times
+they underwent a curious evolution, as the conception
+of Babylon and Egypt is traced through
+Assyria to Greece. The Wings, which had been associated
+at first with the fore limb of the typical dragon,
+become characteristic of the Lion, and of the poet's
+winged Horse, and finally of the Human figure itself,
+<span class='pagenum'><a name="Page_17" id="Page_17">[Pg 17]</a></span>
+carved on the great columns of the Greek temples of
+Ephesus. These flying animals are historically descendants
+of the same common stock with the dragons
+of China and Japan, which still preserve the aspect
+of reptiles. Their interest is chiefly in evidence of
+a latent spirit of evolution in days too remote for its
+meaning to be now understood, which has carried the
+winged forms higher and ever higher in grade of
+organisation, till their wings ceased to be associated
+with feelings of terror. The Hebrew cherubim are
+regarded by H. E. Ryle, Bishop of Exeter, as probably
+Dragons, and the figure of the conventional
+angel is the human form of the Dragon.</p>
+
+<div class="figcenter" style="width: 480px;">
+<a name="Fig_4" id="Fig_4"></a>
+<span class="caption">FIG. 4. &nbsp; FIGURE FROM THE TEMPLE OF EPHESUS</span>
+<img src="images/i_033.jpg" width="480" height="636" alt="FIG. 4. FIGURE FROM THE TEMPLE OF EPHESUS" title="" />
+</div>
+
+
+<h4>ORGANS OF FLIGHT</h4>
+
+<p>Turning from this reference to the realm of mythology
+to existing nature, the power of flight is
+popularly associated with all the chief types of
+vertebrate animals&mdash;fishes, frogs, lizards, birds, and
+mammals. Many of the animals ill deserve the
+name of flyers, and most are exceptions to different
+conditions of existence which control their kindred,
+but it is convenient to examine for a little the nature
+of the structures by which this movement in the air,
+which is not always flight, is made possible. Certain
+fishes, like the lung-fish Ceratodus, of Queensland,
+and the mud-fish Lepidosiren, are capable of leaving
+the water and living on land, and for a time breathe
+air. But neither these fishes nor Periophthalmus,
+which runs with rapid movement of its fins and
+carries the body more or less out of water, or the
+climbing perch, Anabas, carried out of water over
+the country by Indian jugglers, ever put on the
+slightest approach to wings.</p>
+<p><span class='pagenum'><a name="Page_18" id="Page_18">[Pg 18]</a></span></p>
+
+<h4>FLYING FISHES</h4>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_5" id="Fig_5"></a>
+<span class="caption">FIG. 5. &nbsp; THE FLYING FISH EXOC&#338;TUS</span>
+<p class="center">With the fins extended moving through the air</p>
+<img src="images/i_035.jpg" width="640" height="365" alt="FIG. 5." title="FIG. 5." />
+</div>
+
+<p>The flight of fishes is a kind of parachute support
+not unlike that by which a folded paper is made to
+travel in the air. It is chiefly seen in the numerous
+species of a genus Exoc&#339;tus, allied to the gar-pike
+(Belone), which is common in tropical seas, and
+usually from a foot to eighteen inches long. They
+emerge from the water, and for a time support themselves
+in the air by means of the greatly developed
+breast fins, which sometimes extend backward to the
+tail fin. Although these fins appear to correspond
+to the fore limbs of other animals, they may not
+be moved at the will of the fish like the wing of a
+bird. When the flying fishes are seen in shoals in
+the vicinity of ships, those fins remain extended, so
+that the fish is said sometimes to travel 200 yards
+at a speed of fifteen miles an hour, rising twenty feet
+or more above the surface of the sea, travelling in
+a straight line, though sometimes influenced by the
+wind. Here the organ, which is at once a fin and a<span class='pagenum'><a name="Page_19" id="Page_19">[Pg 19]</a></span>
+wing, consists of a number of thin long rods, or rays,
+which are connected by membrane, and vary in
+length to form an outline not unlike the wing of a
+bird which tapers to a point. The interest of these
+animals is chiefly in the fact that flight is separated
+from the condition of having lungs with which it
+is associated in birds, for although the flying fish has
+an air bladder, there is no duct to connect it with
+the throat.</p>
+
+
+<h4>FLYING FROGS</h4>
+
+<div class="figcenter" style="width: 480px;">
+<a name="Fig_6" id="Fig_6"></a>
+<span class="caption">FIG. 6. &nbsp; THE FLYING FROG (RHACOPHORUS)</span>
+<img src="images/i_036.jpg" width="480" height="548" alt="FIG. 6." title="FIG. 6." />
+<p class="center">The membranes of the foot and
+hand extend between the metatarsal
+and metacarpal bones, as well as the
+bones of the digits.</p>
+</div>
+
+
+<p>Among amphibians the organs of flight are also
+of a parachute kind, but of a different nature. They
+are seen in certain frogs which
+frequent trees, and are limited
+to membranes which extend
+between the diverging digits
+of the hand and foot, forming
+webs as fully developed as in
+the foot of a swimming bird.
+As these frogs leap, the membranes
+are expanded and help
+to support the weight of the
+body, so that the animal descends
+more easily as it moves
+from branch to branch. There
+is no evidence that the bones
+of the digits ever became elongated like the fin rays
+of the flying fish or the wing bones of a Bat; but
+the web suggests the basis of such a wing, and the
+possibilities under which wings may first originate,
+by elongation of the bones of a webbed hand like
+that of a Flying Frog.</p>
+<p><span class='pagenum'><a name="Page_20" id="Page_20">[Pg 20]</a></span></p>
+
+<h4>FLYING LIZARDS</h4>
+
+
+<p>The Reptilia in their several orders are remarkable
+for absence of any modification of the arms which
+might suggest a capacity for acquiring wings, as
+being latent in their organisation. Crocodiles, Tortoises,
+and Serpents are alike of the earth, and not
+of the air. But among Lizards there are small groups
+of animals in which a limited capacity for
+movement through the air is developed.
+It is best known in the family of small
+lizards named Dragons, represented typically
+by the species <i>Draco volans</i> found in the Oriental
+region of the East Indies and Malay Archipelago.</p>
+
+<div class="figcenter" style="width: 620px;">
+<a name="Fig_7" id="Fig_7"></a>
+<span class="caption">FIG. 7. &nbsp; THE FLYING DRAGON, DRACO</span>
+<p class="center">Forming a parachute by means of the extended ribs</p>
+<img src="images/i_037.jpg" width="620" height="480" alt="FIG. 7." title="FIG. 7." />
+</div>
+
+
+<p>The organ of flight is produced in an unexpected
+way, by means of the ribs instead of the limbs. The
+ribs extend outward as far as the arms can stretch,
+and the first five or six are prolonged beyond the
+body so as to spread a fold of skin on each side
+between the arm and the leg. The membrane admits<span class='pagenum'><a name="Page_21" id="Page_21">[Pg 21]</a></span>
+of some movement with the ribs. This arrangement
+forms a parachute, which enables the animal to move
+rapidly among branches of trees, extending the structure
+at will, so that it is used with rapidity too quick
+to be followed by the eye, as it leaps through considerable
+distances.</p>
+
+<p>A less singular aid to movement in the air is found
+in some of the lizards termed Geckos. The so-called
+Flying Gecko (<i>Platydactylus homalocephalus</i>) has a
+fringe unconnected with ribs, which extends laterally
+on the sides of the body and tail, as well as at the
+back and front of the fore and hind limbs, and between
+the digits, where the web is sometimes almost as
+well developed as among Tree Frogs. This is essentially
+a lateral horizontal frill, extending round the
+body. Its chief interest is in the circumstance that it
+includes a membrane which extends between the wrist
+bones and the shoulder on the front of the arm. That
+is the only part of the fringe which represents the wing
+membrane of a bird. The fossil flying reptiles have
+not only that membrane, but the lateral membranes
+at the sides of the body and behind the arms.</p>
+
+<p>Other lizards have the skin developed in the
+direction of the circumference of the body. In the
+Australian Chlamydosaurus it forms an immense
+frill round the neck like a medi&aelig;val collar. But
+though such an adornment might break a fall, it
+could not be regarded as an organ of flight.</p>
+
+
+<h4>FLYING BIRDS</h4>
+
+
+<p>The wings of birds, when they are developed so as
+to minister to flight, are all made upon one plan; but
+as examples of the variation which the organs contributing
+to make the fore limb manifest, I may
+<span class='pagenum'><a name="Page_22" id="Page_22">[Pg 22]</a></span>
+instance the short swimming limb of the Penguin,
+the practically useless rudiment of a wing found in
+the Ostrich or Kiwi, and the fully developed wing of
+the Pigeon. The wings of birds obtain an extensive
+surface to support the animal by muscular movements
+of three modifications of structure. First, the bones
+of the fore limb are so shaped that they cannot, in
+existing birds, be applied to the ground for support
+and be used like the limbs of quadrupeds, and are
+therefore folded up at the sides of the body, and<span class='pagenum'><a name="Page_23" id="Page_23">[Pg 23]</a></span>
+carried in an unused or useless state so long as the
+animal hops on the ground or walks, balancing its
+weight on the hind legs. Secondly, there are two
+small folds of skin, less conspicuous than those on
+the arms of Geckos; one is between the wrist bones
+and the shoulder, and the smaller hinder membrane
+is between the upper arm and the body. These
+membranous expansions are insignificant, and would
+in themselves be inadequate to support the body or
+materially assist its movements. Thirdly, the bird
+develops appendages to the skin which are familiarly
+known as feathers, and the large feathers which make
+the wing are attached to the skin covering the lower
+arm bone named the ulna, and the other bones which
+represent the wrist and hand. The area and form of
+the bird's wing are due to individual appendages to
+the skin, which are unknown in any other group of
+animals. Between the extended wing of the Albatross,
+measuring eleven feet in spread, and the condition
+in the Kiwi of New Zealand, in which the
+wing is vanishing, there is every possible variation in
+size and form. As a rule, the larger the animal the
+smaller is the wing area. The problem of the origin
+of the bird's wing is not to be explained by study of
+existing animals; for the rowing organ of the Penguin,
+which in itself would never suggest flight,
+becomes an organ of flight in other birds by the
+growth upon it of suitable feathers. Anyone who
+has seen the birds named Divers feeding under water,
+swimming rapidly with their wings, might never
+suspect that they were also organs of aerial flight.
+The Ostrich is even more interesting, for it has not
+developed flight, and still retains at the extremities
+of two of the digits the slender claws of a limb
+which was originally no wing at all, but the support
+of a four-footed animal (<a href="#Fig_46">Fig. 46, p. 130</a>).</p>
+
+<div class="figcenter" style="width: 480px;">
+<a name="Fig_8" id="Fig_8"></a>
+<span class="caption">FIG. 8. &nbsp;  POSITION OF BIRDS IN FLIGHT</span>
+<img src="images/i_039.jpg" width="480" height="481" alt="FIG. 8.  POSITION OF BIRDS IN FLIGHT" title="FIG. 8." />
+</div>
+
+<p><span class='pagenum'><a name="Page_24" id="Page_24">[Pg 24]</a></span></p>
+<h4>FLYING MAMMALS</h4>
+
+<p>Flight is also developed among mammals. The
+Insectivora include several interesting examples of
+animals which are capable of a certain motion through
+the air. In the tropical forests of the Malay Archipelago
+are animals known as Flying Squirrels, Flying
+Opossums, Flying Lemurs, Flying
+Foxes, in which the skin extends
+outward laterally from the sides
+of the body so as to connect the
+fore limbs with the hind limbs,
+and is also prolonged backward
+from the hind limbs to the tail.
+The four digits are never elongated;
+the bones of the fore limb
+are neither longer nor larger than
+those of the hind limb, and the
+foot terminates in five little claws
+as in other four-footed animals.
+This condition is adapted for the arboreal life which
+those animals live, leaping from branch to branch,
+feeding on fruits and leaves, and in some cases
+upon insects. These mammals may be compared
+with the Flying Geckos among reptiles in their
+parachute-like support by extension of the skin,
+which gives them one of the conditions of support
+which contribute to constitute flight.</p>
+
+<div class="figcenter" style="width: 423px;">
+<a name="Fig_9" id="Fig_9"></a>
+<span class="caption">FIG. 9. &nbsp; FLYING SQUIRREL (PTEROMYS)</span>
+<img src="images/i_041.jpg" width="423" height="640" alt="FIG. 9." title="FIG. 9." />
+</div>
+
+<p><i>Bats.</i>&mdash;One entire order of mammals&mdash;the Bats&mdash;not
+only possess true wings, but are capable of flight
+which is sustained, and in some cases powerful. The
+wings are clothed with short hair like the rest of the
+<span class='pagenum'><a name="Page_25" id="Page_25">[Pg 25]</a></span>
+body, and thus the instrument of flight is unlike that
+of a bird. The flight of a Bat differs from that
+of all other animals in being dependent upon a
+modification of the bones of the fore limb, which,
+without interfering with the animal's movements as
+a quadruped, secures an extension of the wing which
+is not inferior in area to that which the bird obtains
+by elongation of the bones of the arm and fore-arm
+and its feathers. The distinctive peculiarity of the
+Bat's wing is in the circumstance that four of the
+digits of the hand have their bones prolonged to
+a length which is often equal to the combined length
+of the arm and fore-arm. The bones of the digits<span class='pagenum'><a name="Page_26" id="Page_26">[Pg 26]</a></span>
+diverge like the ribs of an umbrella, and between
+them is the wing membrane, which extends from the
+sides of the body outward, unites the fore limb with
+the hind limb, and is prolonged down the tail as
+in the Flying Foxes. Bats have a small membrane
+in front of the bones of the arm and fore-arm
+stretching between the shoulder and the wrist, which
+corresponds with the wing membrane of a bird; but
+the remainder of the membranes in Bats' wings are
+absent in birds, because their function is performed
+by feathers which give the wing its area. The
+elongated digits of the Bat's wing are folded together
+and carried at the sides of the body as though they
+were a few quill pens attached to its wrist, where the
+one digit, which is applied to the ground in walking,
+terminates in a claw.</p>
+
+<div class="figcenter" style="width: 551px;">
+<a name="Fig_10" id="Fig_10"></a>
+<span class="caption">FIG. 10 &nbsp; NEW ZEALAND BAT FLYING. BARBASTELLE WALKING</span>
+<img src="images/i_042.jpg" width="551" height="480" alt="FIG. 10" title="FIG. 10" />
+</div>
+
+<p>The organs which support animals in the air are
+thus seen to be more or less dissimilar in each of the
+great groups of animals. They fall into three chief
+types: first, the parachute; secondly, the wing due
+to the feathers appended to the skin; and thirdly, the
+wing formed of membrane, supported by enormous
+elongation of the small bones of the back of the
+hand and fingers. The two types of true wings are
+limited to birds and bats; and no living reptile
+approximates to developing such an organ of flight
+as a wing. Judged, therefore, by the method of comparing
+the anatomical structures of one animal with
+another, which is termed "comparative anatomy," the
+existence of flying reptiles might be pronounced
+impossible. But in the light which the revelations
+of geology afford, our convictions become tempered
+with modesty; and we learn that with Nature nothing
+is impossible in development of animal structure.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_27" id="Page_27">[Pg 27]</a></span></p>
+<h2><a name="CHAPTER_V" id="CHAPTER_V"></a><small>CHAPTER V</small><br /><br />
+
+DISCOVERY OF THE
+PTERODACTYLE</h2>
+
+
+<p>Late in the eighteenth century, in 1784, a small
+fossil animal with wings began to be known
+through the writings of Collini, as found in the white
+lithographic limestone of Solenhofen in Bavaria, and
+was regarded by him as a former inhabitant of the
+sea. The foremost naturalist of the time, the citizen
+Cuvier&mdash;for it was in the days of the French Republic&mdash;in
+1801, in lucid language, interpreted the animal as
+a genus of Saurians. That word, so familiar at the
+present day, was used in the first half of the century
+to include Lizards and Crocodiles; and described
+animals akin to reptiles which were manifestly related
+neither to Serpents nor Turtles. But the term
+saurian is no longer in favour, and has faded from
+science, and is interesting only in ancient history of
+progress. The lizards soon became classed in close
+alliance with snakes. And the crocodiles, with the
+Hatteria, were united with chelonians. Most modern
+naturalists who use the term saurian still make it
+an equivalent of lizard, or an animal of the lizard
+kind.</p>
+<p><span class='pagenum'><a name="Page_28" id="Page_28">[Pg 28]</a></span></p>
+
+<h4>CUVIER</h4>
+
+<div class="figcenter" style="width: 480px;">
+<a name="Fig_11" id="Fig_11"></a>
+<span class="caption">FIG. 11. &nbsp; <i>PTERODACTYLUS LONGIROSTRIS</i> (Cuvier)</span>
+<img src="images/i_045.jpg" width="480" height="486" alt="FIG. 11." title="FIG. 11." />
+<p class="center">The remains are preserved with the neck arched over the back, and the jaws
+opened upward</p>
+</div>
+
+
+<p>Cuvier defined this fossil from Solenhofen as distinguished
+by the extreme elongation of the fourth
+digit of the hand, and from that character invented
+for the animal the name Pterodactyle. He tells us
+that its flight was not due to prolongation of the ribs,
+as among the living lizards named Dragons; or to a
+wing formed without the digits being distinguishable
+from each other, as among Birds; nor with only one
+digit free from the wing, as among Bats; but by<span class='pagenum'><a name="Page_29" id="Page_29">[Pg 29]</a></span>
+having the wing supported mainly by a single greatly
+elongated digit, while all the others are short and
+terminate in claws. Cuvier described the amazing
+animal in detail, part by part; and such has been the
+influence of his clear words and fame as a great
+anatomist that nearly every writer in after-years,
+in French and in English, repeated Cuvier's conclusion,
+maintained to the end, that the animal is a
+saurian.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_12" id="Fig_12"></a>
+<span class="caption">FIG. 12. &nbsp; THE SKELETON OF <i>PTERODACTYLUS LONGIROSTRIS</i></span>
+<img src="images/i_046.jpg" width="640" height="404" alt="FIG. 12." title="FIG. 12." />
+<p class="center">Reconstructed from the scattered bones in Fig. 14, showing the limbs
+on the left side</p>
+</div>
+
+<p>Long before fashion determined, as an article of
+educated belief, that fossil animals exist chiefly to
+bridge over the gaps between those which still survive,
+the scientific men of Germany were inclined to
+see in the Pterodactyle such an intermediate type
+of life. At first S&ouml;mmerring and Wagler would
+have placed the Pterodactyle between mammals
+and birds.</p>
+<p><span class='pagenum'><a name="Page_30" id="Page_30">[Pg 30]</a></span></p>
+
+<h4>GOLDFUSS</h4>
+
+<div class="figcenter" style="width: 541px;">
+<a name="Fig_13" id="Fig_13"></a>
+<span class="caption">FIG. 13. &nbsp; THE <i>PTERODACTYLUS LONGIROSTRIS</i> RESTORED
+FROM THE REMAINS IN FIG. 11</span>
+<img src="images/i_047.jpg" width="541" height="480" alt="FIG. 13." title="FIG. 13." />
+<p class="center">Showing positions of the wing membranes with the animal at rest</p>
+</div>
+
+<p>But the accomplished naturalist Goldfuss, who
+described another fine skeleton of a Pterodactyle
+in 1831, saw in this flying animal an indication of
+the course taken by Nature in changing the reptilian
+organisation to that of birds and mammals. It is
+the first flash of light on a dark problem, and its
+brilliance of inference has never been equalled. Its
+effects were seen when Prince Charles Bonaparte,
+the eminent ornithologist, in Italy, suggested for the
+group the name Ornithosauria; when the profound
+anatomist de Blainville, in France, placed the short-tailed
+animal in a class between Reptiles and Birds
+named Pterodactylia; and Andreas Wagner, of
+Munich, who had more Pterodactyles to judge from<span class='pagenum'><a name="Page_31" id="Page_31">[Pg 31]</a></span>
+than his predecessors, saw in the fossil animal a
+saurian in transition to a bird.</p>
+
+
+<h4>VON MEYER</h4>
+
+<p>But the German interpretation is not uniform,
+and Hermann von Meyer, the banker-naturalist of
+Frankfurt a./M., who made himself conversant with
+all that his predecessors knew, and enlarged knowledge
+of the Pterodactyles on the most critical facts
+of structure, continued to regard them as true reptiles,
+but flying reptiles. Such is the influence of von
+Meyer that all parts of the world have shown a
+disposition to reflect his opinions, especially as they
+practically coincide with the earlier teaching of
+Cuvier. Owen and Huxley in England, Cope and
+Marsh in America, Gaudry in France, and Zittel in
+Germany have all placed the Pterodactyles as flying
+reptiles. Their judgment is emphatic. But there is
+weight of competent opinion to endorse the evolutionary
+teaching of Goldfuss that they rise above
+reptiles. To form an independent opinion the modern
+student must examine the animals, weigh their characters
+bone by bone, familiarise himself, if possible,
+with some of the rocks in which they are found;
+to comprehend the conditions under which the fossils
+are preserved, which have added not a little to the
+interest in Pterodactyles, and to the difficulty of
+interpretation.</p>
+
+
+<h4>GEOLOGICAL HISTORY OF PTERODACTYLES IN
+GERMANY</h4>
+
+<p>We may briefly recapitulate the geological history.
+Those remains of Ornithosaurs which have been mentioned,
+with a multitude of others which are the glory<span class='pagenum'><a name="Page_32" id="Page_32">[Pg 32]</a></span>
+of the museums of Munich, Stuttgart, T&uuml;bingen,
+Heidelberg, Bonn, Haarlem, and London, have all
+been found in working the lithographic stone of
+Bavaria. The whitish yellow limestone forms low,
+flat-topped hills, now isolated from each other by
+natural denudation, which has removed the intervening
+rock. The stone is found at some distance
+north of the Danube, in a line due north of Augsburg,
+in the country about Pappenheim, and especially at
+the villages of Solenhofen, Eichst&auml;dt, Kelheim, and
+Nusplingen. These beds belong to the rocks which
+are named White Jura limestone in Germany, which
+is of about the same geological age as the Kimeridge
+clay in England. Much of it divides into very thin
+layers, and in these planes of separation the fossils
+are found. They include the <i>Ammonites lithographicus</i>
+and a multitude of marine shells, king
+crabs and other Crustacea, sea-urchins, and other
+fossils, showing that the deposit was formed in the
+sea. The preservation of jelly-fish, which so soon
+disappear when left dry on the beach, shows that the
+ancient calcareous mud had unusual power of preserving
+fossils. Into this sea, with its fishes great
+and small, came land plants from off the land, dragonflies
+and other insects, tortoises and lizards, Pterodactyles
+with their flying organs, and birds still
+clothed with feathers. Sometimes the wing membranes
+of the flying reptiles are found fully stretched
+by the wing finger, as in examples to be seen at
+Munich and in the Yale Museum in Newhaven, in
+America. At Haarlem there is an example in which
+the wing membrane appears to be folded much as in
+the wing of a Bat, when the animal hangs suspended,
+with the flying membrane bent into a few wide undulations.<span class='pagenum'><a name="Page_33" id="Page_33">[Pg 33]</a></span></p>
+
+<p>The Solenhofen Slate belongs to about the middle
+period of the history of flying reptiles, for they
+range through the Secondary epochs of geological
+time. Remains are recorded in Germany from the
+Keuper beds at the top of the Trias, which is the
+bottom division of the Secondary strata; and I believe
+I have seen fragments of their bones from
+the somewhat older Muschelkalk of Germany.</p>
+
+
+<h4>THEIR HISTORY IN ENGLAND</h4>
+
+<p>In England the remains are found for the first time
+in the Lower Lias of Lyme Regis, in Dorset, and the
+Upper Lias of Whitby, in Yorkshire. In W&uuml;rtemberg
+they occur on the same horizons. They reappear in
+England, in every subsequent age, when the conditions
+of the strata and their fossils give evidence of
+near proximity to land. In the Stonesfield Slate of
+Stonesfield, in Oxfordshire, the bones are found
+isolated, but indicate animals of some size, though
+not so large as the rare bones of reputed true
+birds which appear to have left their remains in
+the same deposit.</p>
+
+<p>At least two Pterodactyles are found in the Oxford
+clay, known from more or less fragmentary remains or
+isolated bones; just as they occur in the Kimeridge
+Clay, Purbeck Limestone, Wealden sandstones, and
+especially in newer Secondary rocks, named Gault,
+Upper Greensand, and Chalk, in the south-east of
+England.</p>
+
+<p>Owing to exceptional facilities for collecting, in
+consequence of the Cambridge Greensand being
+excavated for the valuable mineral phosphate of
+lime it contains, more than a thousand bones are
+preserved, more or less broken and battered, in the<span class='pagenum'><a name="Page_34" id="Page_34">[Pg 34]</a></span>
+Woodwardian Museum of the University of Cambridge
+alone. To give some idea of their abundance,
+it may be stated that they were mostly gathered
+during two or three years, as a matter of business,
+by an intelligent foreman of washers of the nodules
+of phosphate of lime, which, in commerce, are named
+coprolites. He soon learned to distinguish Pterodactyle
+bones from other fossils by their texture, and
+learned the anatomical names of bones from specimens
+in the University Museum. This workman,
+Mr. Pond, employed by Mr. William Farren, brought
+together not only the best of the remains at Cambridge,
+but most of those in the museums at York
+and in London, and the thousands of less perfect
+specimens in public and private collections which
+passed through the present writer's hands in endeavours
+to secure for the University useful illustrations
+of the animal's structure. These fragments,
+among which there are few entire bones, are valuable,
+for they have afforded opportunities of examining
+the articular ends of bones in every aspect, which
+is not possible when similar organic remains are embedded
+in rock in their natural connexions.</p>
+
+<p>In England Flying Reptiles disappear with the
+Chalk. In that period they were widely distributed,
+being found in Bohemia, in Brazil, and Kansas in the
+United States, as well as in Kent and other parts of
+England. They attained their largest dimensions in
+this period of geological time. One imperfect fragment
+of a bone from the Laramie rocks of Canada
+was described, I believe, by Cope, though not identified
+by him as Ornithosaurian, and is probably newer
+than other remains.</p>
+<p><span class='pagenum'><a name="Page_35" id="Page_35">[Pg 35]</a></span></p>
+
+<h4>ASPECT OF PTERODACTYLES</h4>
+
+<p>If this series of animals could all be brought
+together they would vary greatly in aspect and
+stature, as well as in structure. Some have the head
+enormously long, in others it is large and deep,
+characters which are shared by extinct reptiles which
+do not fly, and to which some birds may approximate;
+while in a few the head is small and compact,
+no more conspicuous, relatively, than the head of
+a Sparrow. The neck may be slender like that of
+a Heron, or strong like that of an Eagle; the back is
+always short, and the tail may be inconspicuous, or
+as long as the back and neck together. These flying
+reptiles frequently have the proportions of the limbs
+similar to those of a Bat, with fore legs strong and
+hind legs relatively small; while in some the limbs
+are as long, proportionately, and graceful as those of
+a Deer. With these differences in proportions of the
+body are associated great differences in the relative
+length of the wing and spread of the wing membranes.</p>
+
+
+<h4>DIMENSIONS OF THE ANIMALS</h4>
+
+<p>The dimensions of the animals have probably
+varied in all periods of geological time. The
+smallest, in the Lithographic Slate, are smaller than
+Sparrows, while associated with them are others in
+which the drumstick bone of the leg is eight inches
+long. In the Cambridge Greensand and Chalk imperfect
+specimens occur, showing that the upper arm
+bones are larger than those of an Ox. The shaft is
+one and a half inches in diameter and the ends three
+inches wide. Such remains may indicate Pterodactyles
+not inferior in size to the extinct Moas of<span class='pagenum'><a name="Page_36" id="Page_36">[Pg 36]</a></span>
+New Zealand, but with immensely larger heads,
+animals far larger than birds of flight.</p>
+
+<p>The late Sir Richard Owen, on first seeing these
+fragmentary remains, said "the flying reptile with
+outstretched pinions must have appeared like the
+soaring Roc of Arabian romance, but with the features
+of leathern wings with crooked claws superinduced,
+and gaping mouth with threatening teeth."
+Eventually we shall obtain more exact ideas of their
+aspect, when the structures of the several regions of
+the body have been examined. The great dimensions
+of the stretch of wing, often computed at
+twenty feet in the larger examples, might lead to
+expectations of great weight of body, if it were not
+known that an albatross, with wings spreading
+eleven feet, only weighs about seventeen pounds.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_37" id="Page_37">[Pg 37]</a></span></p>
+<h2><a name="CHAPTER_VI" id="CHAPTER_VI"></a><small>CHAPTER VI</small><br /><br />
+
+HOW ANIMALS ARE INTERPRETED
+BY THEIR BONES</h2>
+
+
+<p>There is only one safe path which the naturalist
+may follow who would tell the story of the
+meaning and nature of an extinct type of animal
+life, and that is to compare it as fully as possible in
+its several bones, and as a whole, with other animals,
+especially with those which survive. It is easy to
+fix the place in nature of living animals and determine
+their mutual relations to each other, because all
+the organs&mdash;vital as well as locomotive&mdash;are available
+for comparison. On such evidence they are
+grouped together into the large divisions of Beasts,
+Birds, and Reptiles; as well as placed in smaller
+divisions termed Orders, which are based upon less
+important modifications of fundamental structures.
+All these characteristic organs have usually disappeared
+in the fossil. Hence a new method of
+study of the hard parts of the skeleton, which alone
+are preserved, is used in the endeavour to discover
+how the Flying Reptile or other extinct animal is to
+be classified, and how it acquired its characters or
+came into existence.</p>
+<p><span class='pagenum'><a name="Page_38" id="Page_38">[Pg 38]</a></span></p>
+
+<h4>VARIATIONS OF BONES AMONG MAMMALIA</h4>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_14" id="Fig_14"></a>
+<span class="caption">FIG. 14. &nbsp; THE FORE LIMB IN FOUR TYPES OF MAMMALS</span>
+<img src="images/i_055.jpg" width="640" height="454" alt="FIG. 14." title="FIG. 14." />
+<p class="center">Comparison of the fore limb in mammals, showing variation
+of form of the bones with function</p>
+</div>
+
+
+<p>Resemblances and differences in the bones are
+easily over-estimated in importance as evidence of
+pedigree relationship. The Mammalia show, by
+means of such skeletons as are exhibited in any
+Natural History Museum, how small is the importance
+to be attached to even the existence of any
+group of bones in determining its grade of organisation.
+The whole Whale tribe suckle their young and
+conform to the distinctive characters in brain and
+lungs which mark them as being mammals. But if
+there is one part of the skeleton more than another
+which distinguishes the Mammalia, it is the girdle of
+bones at the hips which supports the hind limbs. It
+is characterised by the bone named the ilium being<span class='pagenum'><a name="Page_39" id="Page_39">[Pg 39]</a></span>
+uniformly directed forward. Yet in the Whale tribe
+the hip-girdle and the hind limb which it usually
+supports are so faintly indicated as to be practically
+lost; while the fore limb becomes a paddle without
+distinction of digits, and is therefore devoid of hoofs
+or claws, which are usual terminations of the extremities
+in mammals. Yet this swimming paddle, with
+its ill-defined bones&mdash;sometimes astonishing in number,
+as well as in fewness of the finger bones&mdash;is
+represented by the burrowing fore limb of the Mole,
+which lives underground; by the elongated hoofed
+legs of the Giraffe, which lives on plains; and the
+extended arm and finger bones of the Bat, which are
+equally mammals with the Whale. From such comparison
+it is seen that no proportion, or form, or
+length, or use of the bones of the limbs, or even the
+presence of limbs, is necessarily characteristic of a
+mammal. No limitation can be placed upon the
+possible diversity of form or development of bones
+in unknown animals, when they are considered in the
+light of such experience of varied structural conditions
+in living members of a single class.</p>
+
+<p>What is true for the limbs and the bony arches
+which support them is true for the backbone also, for
+the ribs, and to some extent for the skull. The neck
+in the Whale is shortened almost beyond recognition.
+In the Giraffe the same seven vertebr&aelig; are elongated
+into a marvellous neck; so that in the technical
+definition of a mammal both are said to have seven
+neck vertebr&aelig;. Yet exceptions show a capacity for
+variation. One of the Sloths reduces the number to
+six, while another has nine vertebr&aelig; in the neck;
+proving that there is no necessary difference between
+a mammal and a reptile when judged by a character<span class='pagenum'><a name="Page_40" id="Page_40">[Pg 40]</a></span>
+which is typically so distinctive of mammals as the
+number of the neck bones.</p>
+
+<p>The skull varies too, though to a less extent. The
+Great Ant-eater of South America is a mammal absolutely
+without teeth. The Porpoises have a simple
+unvarying row of conical teeth with single roots extending
+along the jaw. And the dental armature of
+the jaws, and relative dimensions of the skull bones,
+exhibit such diversity, in evidence of what may be
+parted with or acquired, that recognition of the many
+reptilian structures and bones in the skull of Ornithorhynchus,
+the Australian Duckbill, demonstrates
+that the difficulties in recognising an animal by its
+bones are real, unless we can discover the Animal
+Type to which the bones belong; and that there is
+very little in osteology which may not be lost without
+affecting an animal's grade of organisation.</p>
+
+
+<h4>VARIATION IN SKIN COVERING OF MAMMALS</h4>
+
+<p>Even the covering of the body varies in the same
+class, or even order of animals, so that the familiar
+growth on the skin is never its only possible covering.
+The Indian ant-eater, named Manis, which
+looks like a gigantic fir-cone, the Armadillo, which
+sheathes the body in rings of bone, bearing only a
+scanty development of hair, are examples of mammalian
+hair, as singular as the quills of a Porcupine,
+the horn of a Rhinoceros, or the growth of hair of
+varying length and stoutness on different parts of the
+body in various animals, or the imperfect development
+of hair in the marine Cetacea. Among living
+animals it is enough for practical purposes to say
+that a mammal is clothed with hair, but in a fossil<span class='pagenum'><a name="Page_41" id="Page_41">[Pg 41]</a></span>
+state the hair must usually be lost beyond recognition
+from its fineness and shortness of growth.</p>
+
+
+<h4>VARIATION IN SKIN COVERING OF BIRDS</h4>
+
+<p>No Class of living animals is more homogeneous
+than Birds; and well-preserved remains prove that,
+at least as far back in time as the Upper Oolites, birds
+were clothed with feathers of essentially the same
+mode of growth and appearance as the feathers of
+living birds. There may, therefore, be no ground for
+assuming that the covering was ever different, though
+some regions of the skin are free from feathers. Yet
+the variations from fine under-down to the scale-like
+feathers on the wings of a Penguin, or the great
+feathers in the wings of birds of flight, or the double
+quill of the Ostrich group, are calculated to yield
+dissimilar impressions in a fossil state, even if the
+fine down would be preserved in any stratum.</p>
+
+
+<h4>VARIATION IN THE BONES OF BIRDS</h4>
+
+<p>Osteologically there is less variety in the skeleton
+of birds than in other great groups of animals. The
+existing representatives do not exhaust its capability
+for modification. The few specimens of birds hitherto
+found in the Secondary strata have rudely removed
+many differences in the bones which separated living
+birds from reptiles; so that if only the older fossil
+birds were known, and the Tertiary and living birds
+had not existed, a bird might have been defined as
+an animal having its jaw armed with teeth, instead of
+devoid of teeth; with vertebr&aelig; cupped at both ends,
+instead of with a saddle-shaped articulation which in
+front is concave from side from side, and convex from
+above downwards; in which the bones of the hand<span class='pagenum'><a name="Page_42" id="Page_42">[Pg 42]</a></span>
+are separate, so that three digits terminating in claws
+can be applied to the ground, instead of the metacarpal
+bones being united in a solid mass with clawless
+digits; and in which the tail is elongated like
+the tail of a lizard. Yet the limits to variation are
+not to be formulated till Nature has exhausted all
+her resources in efforts to preserve organic types by
+adapting them to changed circumstances. Birds may
+be regarded theoretically as equally capable with
+mammals of parting with almost every distinctive
+structure in the skeleton by which it is best known.
+Even the living frigate bird blends the early joints of
+the backbone into a compact mass like a sacrum.
+The Penguin has a cup-and-ball articulation in the
+early dorsal vertebr&aelig;, with the ball in front. And the
+genus Cypselus has the upper arm bone almost as
+broad as long, unlike the bird type. Such examples
+prove that we are apt to accept the predominant
+structures in an animal type as though they were
+universal, and forget that inferences based, like those
+of early investigators, on limited materials may be
+re-examined with advantage.</p>
+
+
+<h4>VARIATION IN THE BONES OF REPTILES</h4>
+
+<p>The true Reptilia, notwithstanding some strong resemblances
+to Birds in technical characters of the
+skeleton, display among their surviving representatives
+an astonishing diversity in the bony framework
+of the body, exceeding that of the mammalia. This
+unlooked-for capacity for varying the plan of construction
+of the skeleton is in harmony with the
+diversity of structure in groups of extinct animals
+to which the name reptiles has also been given. The
+interval in form is so vast between Serpent and<span class='pagenum'><a name="Page_43" id="Page_43">[Pg 43]</a></span>
+Tortoise, and so considerable in structure of the
+skeleton between these and the several groups of
+Lizards, Crocodiles, and Hatteria, that any other
+diversity could not be more surprising. And the
+inference is reasonable that just as mammals live
+in the air, in the sea, on the earth, and burrow under
+the earth, similar modes of existence might be
+expected for birds and reptiles, though no bird is
+yet known to have put on the aspect of a fish, and
+no reptiles have been discovered which roamed in
+herds like antelopes, or lived in the air like birds
+or bats, unless these fossil flying animals prove on
+examination to justify the name by which they are
+known.</p>
+
+<p>Comparative study of structure in this way demolishes
+the prejudice, born of experience of the
+life which now remains on earth, that the ideas
+of Reptile and of Flight are incongruous, and not
+to be combined in one animal. The comparative
+study of the parts of animals does not leave the
+student in a chaos of possibilities, but teaches us
+that organic structures, which mark the grades of
+life, have only a limited scope of change; while
+Nature flings away every part of the skeleton which
+is not vital, or changes its form with altering circumstances
+of existence, enforced by revolutions of the
+Earth's surface in geological time, in her efforts to
+save organisms from extinction and pass the grade
+of life onward to a later age.</p>
+
+<p>The bones are only of value to the naturalist as
+symbols, inherited or acquired, and vary in value as
+evidence of the nature and association of those vital
+organs which differentiate the great groups of the
+vertebrata.<span class='pagenum'><a name="Page_44" id="Page_44">[Pg 44]</a></span></p>
+
+<p>These distinctive structures, which separate Mammals,
+Birds, and Reptiles, are sometimes demonstrated
+by the impress of their existence left on the bones;
+or sometimes they may be inferred from the characters
+of the skeleton as a whole.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_45" id="Page_45">[Pg 45]</a></span></p>
+<h2><a name="CHAPTER_VII" id="CHAPTER_VII"></a><small>CHAPTER VII</small><br /><br />
+
+INTERPRETATION OF PTERODACTYLES
+BY THEIR SOFT PARTS</h2>
+
+<h4>THE ORGANS WHICH FIX AN ANIMAL'S PLACE
+IN NATURE</h4>
+
+
+<p>We shall endeavour to ascertain what marks
+of its grade of organisation the Pterodactyle
+has to show. The organs which are capable of modifying
+the bones are probably limited to the kidneys,
+the brain, and the organs of respiration. It may be
+sufficient to examine the latter two.</p>
+
+
+<h4>PNEUMATIC FORAMINA IN PTERODACTYLES</h4>
+
+
+
+<p>Hermann von Meyer, the historian of the Ornithosaurs
+of the Lithographic Slate, as early as 1837
+described some Pterodactyle bones from the Lias
+of Franconia, which showed that air was admitted
+into the interior of the bones by apertures near their
+extremities, which, from this circumstance, are known
+as pneumatic foramina. He drew the inference,
+naturally enough, that such a structure is absolute
+proof that the Pterodactyle was a flying animal.
+It was not quite the right form in which the conclusion
+should have been stated, because the Ostrich
+and other birds which do not fly have the principal
+<span class='pagenum'><a name="Page_46" id="Page_46">[Pg 46]</a></span>
+bones pneumatic. Afterwards, in 1859, the larger
+bones which Professor Sedgwick, of Cambridge,
+transmitted to Sir Richard Owen
+established this condition as characteristic
+of the Flying Reptiles of
+the Cambridge Greensand. It was
+thus found as a distinctive structure
+of the bones both at the beginning
+and the close of the geological
+history of these animals. Von
+Meyer remarks that the supposition
+readily follows that in the respiratory
+process there was some similarity
+between Pterodactyles and Birds.
+This cautious statement may perhaps
+be due to the circumstance
+that in many animals air cavities
+are developed in the skull without
+being connected with organs of respiration. It
+is well known that the bulk of the Elephant's head
+is due to the brain cavity being protected with an
+envelope formed of large air cells. Small air cells
+are seen in the skulls of oxen, pigs, and many other
+mammals, as well as in the human forehead. The
+head of a bird like the Owl owes something of its
+imposing appearance to the way in which its mass
+is enlarged by the dense covering of air cells in the
+bones above the brain, like that seen in some Cretaceous
+Pterodactyles. Nor are the skulls of Crocodiles
+or Tortoises exceptions to the general rule that an
+animal's head bones may be pneumatic without
+implying a pneumatic prolongation of air from the
+lungs. The mere presence of air cells without specification
+of the region of the skeleton in which they<span class='pagenum'><a name="Page_47" id="Page_47">[Pg 47]</a></span>
+occur is not remarkable. The holes by which air
+enters the bones are usually much larger in Pterodactyles
+than in Birds, but the entrance to the air cell
+prolonged into the bones is the same in form and
+position in both groups. So far as can be judged
+by this character, there is no difference between them.
+The importance of the comparison can only be appreciated
+by examining the bones side by side. In
+the upper arm bone of a bird, on what is known
+as the ulnar border, near to the shoulder joint, and
+on the side nearest to it, is the entrance to the air
+cell in the humerus. In the Pterodactyle the corresponding
+foramen has the same position, form, and
+size, and is not one large hole, but a reticulation
+of small perforations, one beyond another, exactly
+such as are seen in the entrance to the air cell in the
+bone of a bird, in which the pneumatic character
+is found. For it is not every bird of flight which has
+this pneumatic condition of the bones; and Dr. Crisp
+stated that quite a number of birds&mdash;the Swallow,
+Martin, Snipe, Canary, Wood-wren and Willow-wren,
+Whinchat, Glossy-starling, Spotted-fly-catcher, and
+Black-headed Bunting&mdash;have no air in their bones.
+And it is well known that in many birds, especially
+water birds, it is only the upper bones of the limbs
+which are pneumatic, while the smaller bones retain
+the marrow.</p>
+
+<div class="figcenter" style="width: 366px;">
+<a name="Fig_15" id="Fig_15"></a>
+<span class="caption">FIG. 15. &nbsp; HEAD OF THE HUMERUS OF THE PTERODACTYLE ORNITHOCHEIRUS</span>
+<img src="images/i_063.jpg" width="366" height="640" alt="FIG. 15." title="FIG. 15." />
+<p class="center">Showing position of the pneumatic foramen on the
+ulnar side of the bone as in a bird</p>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_48" id="Page_48">[Pg 48]</a></span></p>
+<h4>LUNGS AND AIR CELLS</h4>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_16" id="Fig_16"></a>
+<span class="caption">FIG. 16. &nbsp; LUNGS OF THE BIRD APTERYX
+PARTLY OPENED ON THE RIGHT-HAND SIDE</span>
+<img src="images/i_065.jpg" width="640" height="420" alt="FIG. 16." title="FIG. 16." />
+<p class="center">The circles are openings of the bronchial tubes on the surface of the lung
+The notches on the inner edges of the lungs are impressions of the ribs<br />
+
+(After R. Owen)</p>
+</div>
+
+
+
+<p>It may be well to remember that the lungs of a
+bird are differently conditioned from those of any
+other animal. Instead of hanging freely suspended
+in the cone-shaped chamber of the thorax formed by
+the ribs and sternum, they are firmly fixed on each
+side, so that the ribs deeply indent them and hold
+them in place. The lungs have the usual internal
+structure, being made up of branching cells. The
+chief peculiarity consists in the way in which the air
+passes not only into them, but through them. The
+air tube of the throat of a bird, unlike that of a
+man, has the organ of voice, not at the upper end
+in the form of a larynx, but at the lower end, forming
+what is termed a syrinx. There is no evidence
+of this in a fossil state, although in a few birds the
+rings of the trach&aelig;a become ossified, and are preserved.
+But below the syrinx the trach&aelig;a divides
+into two bronchi, tubes which carry the ringed
+character into the lungs for some distance, and
+these give off branches termed bronchial tubes, the
+finer subdivisions from which, in their clustered
+minute branching sacs, make up the substance of
+the lung. There is nothing exceptional in that. But
+towards the outer or middle part of the ventral or
+<span class='pagenum'><a name="Page_49" id="Page_49">[Pg 49]</a></span>
+under surface of the lungs, four or five rounded
+openings are seen on each side. Each of these
+openings resembles the entrance of the air cell into
+a bone, since it displays several smaller openings
+which lead to it. Each opening from the lung
+leads to an air cell. Those cells may be regarded as
+the blowing out of the membrane which covers the
+lungs into a film which holds air like a mass of soap
+bubbles, until the whole cavity of the body of a
+bird from neck to tail is occupied by sacculated air
+cells, commonly ten in number, five on each side,
+though two frequently blend at the base of the neck
+in the region of the <b>V</b>-shaped bone named the
+clavicle or furculum, popularly known as the merry-thought.
+Most people have seen some at least of
+<span class='pagenum'><a name="Page_50" id="Page_50">[Pg 50]</a></span>
+these semi-transparent bladder-like air cells beneath
+the skin in the abdominal region of a fowl. The cells
+have names from their positions, and on each side
+one is abdominal, two are thoracic, one clavicular,
+and one cervical, which last is at the base of the
+neck. The clavicular and abdominal air cells are
+perhaps the most interesting. The air cell termed
+clavicular sends a process outward towards the arm,
+along with the blood vessels which supply the arm.
+Thus this air cell, entering the region of the axilla
+or arm-pit, enters the upper arm bone usually on its
+under side, close to the articular head of the humerus,
+and in the same way the air may pass from bone to
+bone through every bone in the fore limb. The hind
+limbs similarly receive air from the abdominal air
+cell, which supplies the femur and other bones of
+the leg, the sacrum, and the tail. But the joints of
+the backbone in front of the sacrum receive their air
+from the cervical air sac. The air cells are not
+limited to the bones, but ramify through the body,
+and in some cases extend among the muscles. A
+bird may be said to breathe not only with its lungs,
+but with its whole body. And it is even affirmed
+that respiration has been carried on through a broken
+arm bone when the throat was closed, and the bird
+under water.</p>
+
+<div class="figcenter" style="width: 488px;">
+<a name="Fig_17" id="Fig_17"></a>
+<span class="caption">FIG. 17. &nbsp;  THE BODY OF AN OSTRICH LAID OPEN
+TO SHOW THE AIR CELLS WHICH EXTEND
+THROUGH ITS LENGTH</span>
+<p class="center">(After Georges Roch&eacute;)</p>
+<img src="images/i_066.jpg" width="488" height="480" alt="FIG. 17." title="FIG. 17." />
+</div>
+
+
+<p>Birds differ greatly in the extent to which the aircell
+system prolonged from the lungs is developed,
+some having the air absent from every bone, while
+others, like the Swift, are reputed to have air in every
+bone of the body.</p>
+
+<p>Comparison shows that in so far as the bones are
+the same in Bird and Ornithosaur, the evidence of
+the air cells entering them extends to resemblance,<span class='pagenum'><a name="Page_51" id="Page_51">[Pg 51]</a></span>
+if not coincidence, in every detail. No living group
+of animals except birds has pneumatic limb bones,
+in relation to the lungs; so that it is reasonable to
+conclude that the identical structures in the bones
+were due to the same cause in both the living and
+extinct groups of animals. It is impossible to say
+that the lungs were identical in Birds and Pterodactyles,
+but so far as evidence goes, there is no
+ground for supposing them to have been different.</p>
+
+
+<h4>THE LUNGS OF REPTILES</h4>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_18" id="Fig_18"></a>
+<span class="caption">FIG. 18. &nbsp; THE SIDE OF THE BODY OF A CHAMELEON</span>
+<p class="center">Ribs removed to show the sacculate branched form of the lung</p>
+<img src="images/i_068.jpg" width="640" height="339" alt="FIG. 18." title="FIG. 18." />
+</div>
+
+
+<p>There is nothing comparable to birds, either in the
+lungs of living reptiles or in their relation to the
+bones. The Chameleon is remarkable in that the
+lung is not a simple bladder prolonged through
+the whole length of the body cavity, as in a serpent,
+but it develops a number of large lateral branches
+visible when the body is laid open. Except near
+the trach&aelig;a, where the tissue has the usual density
+of a lizard lung, the air cell is scarcely more complicated
+than the air bladder of a fish, and does not
+enter into any bone of the skeleton. And although
+<span class='pagenum'><a name="Page_52" id="Page_52">[Pg 52]</a></span>
+many fishes like the Loach have the swim bladder
+surrounded by bone connected with the head, it offers
+no analogy to the pneumatic condition of the bones
+in the Pterodactyle.</p>
+
+
+<h4>THE FORM OF THE BRAIN CAVITY</h4>
+
+<p>But the identity of the pneumatic foramina in
+Birds and Flying Reptiles is not a character which
+stands by itself as evidence of organisation, for a
+mould of the form of the brain case contributes
+evidence of another structural condition which throws
+some light on the nature of Ornithosaurs. Among
+many of the lower animals, such as turtles, the brain
+does not fill the chamber in the dry skull, in which
+the same bones are found as are moulded upon the
+brain in higher animals. For the brain case in such
+reptiles is commonly an envelope of cartilage, as
+among certain fishes; and except among serpents,
+the Ophidia, the bones do not completely close the
+reptilian brain case in front. The brain fills the brain
+case completely among birds. A mould from its
+interior is almost as definite in displaying the several
+parts of which it is formed as the actual brain would
+be. And the chief regions of the brain in a bird&mdash;cerebrum,
+optic lobes, cerebellum&mdash;show singularly
+little variation in proportion or position. The essential
+fact in a bird's brain, which separates it absolutely
+from all other animals, is that the pair of nerve
+masses known as the optic lobes are thrust out at
+the sides, so that the large cerebral hemispheres
+extend partly over them as they extend between
+them to abut against the cerebellum. This remarkable
+condition has no parallel among other vertebrate
+animals. In Fishes, Amphibians, Reptiles, and
+<span class='pagenum'><a name="Page_53" id="Page_53">[Pg 53]</a></span>
+Mammals the linear succession of the several parts
+of the brain is never departed from; and any appearance
+of variation from it among mammals is more
+apparent than real, for the linear succession may be
+seen in the young calf till the cerebral hemispheres
+grow upward and lop backward, so as to hide the
+relatively small brain masses which correspond to
+the optic lobes of reptiles, extending over these
+corpora-quadrigemina, as they are named, so as to
+cover more or less of the mass of the cerebellum.
+From these conditions of the brain and skull, it
+would not be possible to mistake a mould from
+<span class='pagenum'><a name="Page_54" id="Page_54">[Pg 54]</a></span>
+the brain case of a bird for that of a reptile, though
+in some conditions of preservation it is conceivable
+that the mould of the brain of a bird might be distinguished
+with difficulty from that of the brain in the
+lowest mammals. Taken by itself, the avian form of
+brain in an animal would be as good evidence that
+its grade of organisation was that of a bird as could
+be offered.</p>
+
+<div class="figcenter" style="width: 480px;">
+<a name="Fig_19" id="Fig_19"></a>
+<span class="caption">FIG. 19. &nbsp; THE FORM OF THE BRAIN</span>
+<img src="images/i_070.jpg" width="480" height="543" alt="FIG. 19." title="FIG. 19." />
+</div>
+
+
+<h4>THE BRAIN IN SOLENHOFEN PTERODACTYLES</h4>
+
+<p>It happens that moulds of the brain of Pterodactyles,
+more or less complete, are met with of
+all geological ages&mdash;Liassic, Oolitic, and Cretaceous.
+The Solenhofen Slate is the only deposit in Europe
+in which Pterodactyle skulls can be said to be fairly
+numerous. They commonly have the bones so thin
+as to show the form of the upper surface of the
+mould of the brain, or the bones have scaled off
+the mould, or remain in the counterpart slab of stone,
+so as to lay bare the shape of the brain mass.</p>
+
+<p>In the Museum at Heidelberg a skull of this kind
+is seen in the long-tailed genus of Pterodactyles
+named Rhamphorhynchus. It shows the large
+rounded cerebral hemispheres, which extend in
+front of cerebral masses of smaller size a little
+below them in position, which perhaps are as like
+the brain of a monotreme mammal as a bird.</p>
+
+<p>The short-tailed Pterodactylus described by Cuvier
+has the cerebral hemispheres very similar to those
+of a bird, but the relations of the hinder parts of
+the brain to each other are less clear.</p>
+
+<p>The first specimen to show the back of the brain
+was found by Mr. John Francis Walker, <small>M.A.</small>, in the
+Cambridge Greensand. I was able to remove the
+<span class='pagenum'><a name="Page_55" id="Page_55">[Pg 55]</a></span>
+thick covering of cellular bone which originally
+extended above it, and thus expose evidence that
+in the mutual relations of the fore and hind parts
+of the brain bird and ornithosaur were practically
+identical. Another Cambridge Greensand skull
+showed that in the genus Ornithocheirus the optic
+lobes of the brain are developed laterally, as in birds.
+That skull was isolated and imperfect. But about the
+same time the late Rev. W. Fox, of Brixton, in the
+Isle of Wight, obtained from Wealden beds another
+skull, with jaws, teeth, and the principal bones of
+the skeleton, which showed that the Wealden Pterodactyle
+Ornithodesmus had a similar and bird-like
+brain. In 1888 Mr. E. T. Newton, <small>F.R.S.</small>, obtained a
+skull from the Upper Lias, uncrushed and free from
+distortion. This made known the natural mould of
+the brain, which shows the cerebral hemispheres, optic
+lobes, and cerebellum more distinctly than in the specimens
+previously known. In some respects it recalls
+the Heidelberg brain of Rhamphorhynchus in the
+apparently transverse subdivision of the optic lobes,
+but it is unmistakably bird-like, and quite unlike any
+reptile.</p>
+
+
+<h4>IMPORTANCE OF THE BRAIN AND BREATHING
+ORGANS</h4>
+
+<p>So far as the evidence goes, it appears that these
+fossil flying animals show no substantial differences
+from birds, either in the mould of the brain or the
+impress of the breathing organs upon the bones.
+These approximations to birds of the nervous and
+respiratory systems, which are beyond question two
+of the most important of the vital organs of an
+animal, and distinctive beyond all others of birds,<span class='pagenum'><a name="Page_56" id="Page_56">[Pg 56]</a></span>
+place the naturalist in a singular dilemma. He must
+elect whether he will trust his interpretation to the
+soft organs, which among existing animals never vary
+their type in the great classes of vertebrate animals,
+and on which the animal is defined as something
+distinct from its envelope the skeleton and its appendages
+the limbs, or whether he will ignore them.
+The answer must choose substantially between belief
+that the existing order of Nature gives warrant for
+believing that these vital characteristics which have
+been discussed might equally coexist with the skeleton
+of a mammal or a reptile, as with that of a bird,
+for which there is no particle of evidence in existing
+life. Or, as an alternative, the fact must be accepted
+that birds only have such vital organs as are here
+found, and therefore the skeleton, that may be associated
+with them, cannot affect the reference of the
+type to the same division of the animal kingdom as
+birds. The decision need not be made without further
+consideration. But brain and breathing organs of the
+avian type are structures of a different order of
+stability in most animals from the bones, which vary
+to a remarkable extent in almost every ordinal group
+of animals.</p>
+
+
+<h4>TEMPERATURE OF THE BLOOD</h4>
+
+<p>The organs of circulation and digestion are necessarily
+unknown. There are reasons why the blood
+may have been hot, such as the evidences from the
+wings of exceptional activity; though the temperature
+depends more upon the amount of blood in the
+body than upon the apparatus by which it is distributed.
+We speak of a Crocodile as cold-blooded,
+yet it is an animal with a four-chambered heart not<span class='pagenum'><a name="Page_57" id="Page_57">[Pg 57]</a></span>
+incomparable with that of a bird. On the other hand,
+the Tunny, a sort of giant Mackerel, is a fish with a
+three-chambered heart, only breathing the air dissolved
+in water, which has blood as warm as a
+mammal, its temperature being compared to that of
+a pig. Several fishes have blood as warm as that of
+Manis, the scaly ant-eater; and many birds have
+hotter blood than mammals. The term "hot-blooded,"
+as distinct from "cold-blooded," applied to animals, is
+relative to the arbitrary human standard of experience,
+and expresses no more than the circumstance
+that mammals and birds are warmer animals than
+reptiles and fishes.</p>
+
+<p>The exceptional temperature of the Flying Fish
+has led to a vague impression that physical activity
+and its effect upon the amount of blood which vigour
+of movement circulates, are more important in raising
+an animal's temperature than possession of the circulatory
+organs commonly associated with hot blood,
+which drive the blood in distinct courses through the
+body and breathing organs. Yet the kind of heart
+which is always associated with vital structures such
+as Pterodactyles are inferred to have possessed from
+the brain mould and the pneumatic foramina in the
+bones, is the four-chambered heart of the bird and
+the mammal. Considering these organs alone&mdash;of
+which the fossil bones yield evidence&mdash;we might
+anticipate, by the law of known association of structures,
+that nothing distinctly reptilian existed in the
+other soft part of the vital organisation, because there
+is no evidence in favour of or against such a possibility.</p>
+
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_58" id="Page_58">[Pg 58]</a></span></p>
+<h2><a name="CHAPTER_VIII" id="CHAPTER_VIII"></a><small>CHAPTER VIII</small><br /><br />
+
+THE PLAN OF THE SKELETON</h2>
+
+
+<p>While these animals are incontestably nearer
+to birds than to any other animals in their
+plan of organisation, thus far no proof has been
+found that they are birds, or can be included in
+the same division of vertebrate life with feathered
+animals. It is one of the oldest and soundest teachings
+of Linn&aelig;us that a bird is known by its feathers;
+and the record is a blank as to any covering to the
+skin in Pterodactyles. There is the strongest probability
+against feathers having existed such as are
+known in the Arch&aelig;opteryx, because every Solenhofen
+Ornithosaur appears to have the body devoid
+of visible or preservable covering, while the two birds
+known from the Solenhofen Slate deposit are well
+clothed with feathers in perfect preservation. We
+turn from the skin to the skeleton.</p>
+
+<p>The plan on which the skeleton is constructed
+remains as evidence of the animal's place in nature,
+which is capable of affording demonstration on which
+absolute reliance would have been placed, if the brain
+and pneumatic foramina had remained undiscovered.
+With the entire skeleton before us, it is inconceivable
+that anatomical science should fail to discover the<span class='pagenum'><a name="Page_59" id="Page_59">[Pg 59]</a></span>
+true nature of the animal to which it belonged, by
+the method of comparing one animal with another.
+There is no lack of this kind of evidence of Pterodactyles
+in the three or four scores of skeletons, and
+thousands of isolated or associated bones, preserved
+in the public museums of Europe and America.</p>
+
+<p>I may recall the circumstance that the discovery of
+skeletons of fossil animals has occasionally followed
+upon the interpretation of a single fragment, from
+which the animal has been well defined, and sometimes
+accurately drawn, before it was ever seen. So
+I propose, before drawing any conclusions from the
+skeletons in the entirety of their construction, to
+examine them bone by bone, and region by region,
+for evidence that will manifest the nature of this
+brood of Dragons. Their living kindred, and perhaps
+their extinct allies, assembled as a jury, may be able
+to determine whether resemblances exist between
+them, and whether such similarity between the bones
+as exists is a common inheritance, or is a common
+acquisition due to similar ways of life, and no evidence
+of the grade of the organism among vertebrate
+animals.</p>
+
+<p>The bones of these Ornithosaurs, when found
+isolated, first have to be separated from the organisms
+with which they are associated and mixed in the
+geological strata. This discrimination is accomplished
+in the first instance by means of the texture of the
+surface. The density and polish of the bones is
+even more marked than in the bones of birds, and is
+usually associated with a peculiar thinness of substance
+of the bone, which is comparable to the condition
+in a bird, though usually a little stouter, so
+that the bones resist crushing better. Pterodactyle<span class='pagenum'><a name="Page_60" id="Page_60">[Pg 60]</a></span>
+bones in many instances are recognised by their
+straightness and comparatively uniform dimensions,
+due to the exceptional number of long bones which
+enter into the structure of the wing as compared
+with birds. When the bones are unerringly determined
+as Ornithosaurian, they are placed side by
+side with all the bones which are most like them, till,
+judged by the standard of the structures of living
+animals, the fossil is found to show a composite construction
+as though it were not one animal but many,
+while its individual bones often show equally composite
+characters, as though parts of the corresponding
+bone in several animals had been cunningly fitted
+together and moulded into shape.</p>
+
+
+<h4>THE PLAN OF THE HEAD IN ORNITHOSAURS</h4>
+
+<p>The head is always the most instructive part of an
+animal. It is less than an inch long in the small
+Solenhofen skeleton named <i>Pterodactylus brevirostris</i>,
+and is said to be three feet nine inches long in the
+toothless Pterodactyle Ornithostoma from the Chalk
+of Kansas. Most of these animals have a long,
+slender, conical form of head, tapering to the point
+like the beak of a Heron, forming a long triangle
+when seen from above or from the side. Sometimes
+the head is depressed in front, with the beak flattened
+or rounded as in a Duck or Goose, and occasionally in
+some Wealden and Greensand species the jaws are
+truncated in front in a massive snout quite unlike
+any bird. The back of the head is sometimes
+rounded as among birds, showing a smooth pear-shaped
+posterior convexity in the region of the brain.
+Sometimes the back of the head is square and vertical
+or oblique. Occasionally a great crest of cellular<span class='pagenum'><a name="Page_61" id="Page_61">[Pg 61]</a></span>
+tissue is extended backward from above the brain
+case over the spines of the neck bones.</p>
+
+<p>There are always from two to four lateral openings
+in the skull. First, the nostril is nearest to the extremity
+of the beak. Secondly, the orbits of the
+eyes are placed far backward. These two openings
+are always present. The nostril may incline upward.
+The orbits of the eyes are usually lateral, though
+their upper borders sometimes closely approximate,
+as in the woodpecker-like types from the Solenhofen
+Slate named <i>Pterodactylus Kochi</i>, now separated
+as another genus. In most genera there is an opening
+in the side of the head, between the eye hole and the
+nostril, known as the antorbital vacuity; and another
+opening, which is variable in size and known as the
+temporal vacuity, is placed behind the eye. The
+former is common in the skulls of birds, the latter is
+absent from all birds and found in many reptiles.</p>
+
+<p>The palate is usually imperfectly seen, but English
+and American specimens have shown that it has
+much in common with the palate in birds, though it
+varies greatly in form of the bones in representatives
+from the Lias, Oolites, and Cretaceous rocks.</p>
+
+<p>From the scientific aspect the relative size of the
+head, its form, and the positions and dimensions of
+its apertures and processes, are of little importance
+in comparison with its plan of construction, as evidenced
+by the positions and relations to each other
+of the bones of which it is formed. There usually is
+some difficulty in stating the limits of the bones of
+the skull, because in Pterodactyles, as among birds,
+they usually blend together, so that in the adult
+animal the sutures between the bones are commonly
+obliterated.<span class='pagenum'><a name="Page_62" id="Page_62">[Pg 62]</a></span></p>
+
+<p>Bones have relations to each other and places in
+the head which can only change as the organs with
+which they are associated change their positions. No
+matter what the position of a nostril may be&mdash;at the
+extremity of a long snout, as in an ant-eater, or far
+back at the top of the head in a porpoise, or at the
+side of the head in a bird&mdash;it is always bordered by
+substantially the same bones, which vary in length
+and size with the changing place of the nostril and
+the form of the head. Every region of the head is
+defined by this method of construction; so that eye
+holes and nose holes, brain case and jaw bones,
+palate and teeth, beak, and back of the skull are all
+instructive to those who seek out the life-history of
+these animals. We may briefly examine the head
+of an Ornithosaurian.</p>
+
+
+<h4>BONES ABOUT THE NOSTRIL</h4>
+
+<p>No matter what its form may be, the head of an
+Ornithosaur always terminates in front in a single
+bone called the intermaxillary. It sends a bar of
+bone backward above the visible nostrils, between
+them; and a bar on each side forms the margin of
+the jaw in which teeth are implanted. The bone
+varies in depth, length, sharpness, bluntness, slenderness,
+and massiveness. As the bone becomes long
+the jaw is compressed from side to side, and the
+openings of the nostrils are removed backward to
+an increasing distance from the extremity of the
+beak.</p>
+
+<p>The outer and hinder border of the nostril is made
+by another bone named the maxillary bone, which is
+usually much shorter than the premaxillary. It
+contains the hindermost teeth, which rarely differ
+<span class='pagenum'><a name="Page_63" id="Page_63">[Pg 63]</a></span>
+from those in front, except in sometimes being
+smaller.</p>
+
+<p>The nasal bones, which always make the upper
+and hinder border of the nostrils, meet each other
+above them, in the middle line of the beak.</p>
+
+<div class="figcenter" style="width: 594px;">
+<a name="Fig_20" id="Fig_20"></a>
+<span class="caption">FIG. 20</span>
+<img src="images/i_080.jpg" width="594" height="480" alt="FIG. 20" title="FIG. 20" />
+<p class="center">Showing that the extremity of the jaws in Rhamphorhynchus was
+sheathed in horn as in the giant Kingfisher, since the jaws
+similarly gape in front.<br />
+<br />
+The hyoid bones are below the lower jaw in the Pterodactyle.</p>
+</div>
+
+
+<p>The nostrils are unusually large in the Lias genus
+named Dimorphodon, and small in species of the
+genus Rhamphorhynchus from Solenhofen.  Such
+differences result from the relative dimensions and
+proportions of these three bones which margin the
+nasal vacuity, and by varying growth of their front
+margins or of their hinder margins govern the form
+of the snout.</p>
+
+<p>The jaws are most massive in the genera known from
+the Wealden beds to the Chalk. The palatal surface is
+<span class='pagenum'><a name="Page_64" id="Page_64">[Pg 64]</a></span>
+commonly flat or convex, and often marked by an
+elevated median ridge which corresponds to a groove
+in the lower jaw, though the median ridge sometimes
+divides the palate into two parallel concave channels.
+The jaw is margined with teeth which are rarely
+fewer than ten or more than twenty on each side.
+They are sharp, compressed from side to side, curved
+inward, and never have a saw-like edge on the back
+and front margins. No teeth occur upon the bones
+of the palate.</p>
+
+<p>In most birds there is a large vacuity in the side
+of the head between the nostril and the orbit of the
+eye, partly separated from it by the bone which
+carries the duct for tears named the lachrymal bone.
+The same preorbital vacuity is present in all long-tailed
+Pterodactyles, though it is either less completely
+defined or absent in the group with short
+tails. It affords excellent distinctive characters for
+defining the genera. In the long-tailed genus
+Scaphognathus from Solenhofen this preorbital opening
+is much larger than the nostril, while in Dimorphodon
+these vacuities are of about equal size.
+Rhamphorhynchus is distinguished by the small size
+of the antorbital vacuity, which is placed lower than
+the nostril on the side of the face. The aperture is
+always imperfectly defined in Pterodactylus, and is
+a relatively small vacuity compared with the long
+nostril. In Ptenodracon the antorbital vacuity
+appears to have no existence separate from the nostril
+which adjoins the eye hole. And so far as is known at
+present there is no lateral opening in advance of the
+eye in the skull in any Ornithosaur from Cretaceous
+rocks, though the toothless Ornithostoma is the only
+genus with the skull complete. When a separate
+<span class='pagenum'><a name="Page_65" id="Page_65">[Pg 65]</a></span>
+antorbital vacuity exists, it is bordered by the maxillary
+bone in front, and by the malar bone behind.
+The prefrontal bone is at its upper angle. That bone
+is known in a separate state in reptiles and, I think, in
+monotreme mammals. Its identity is soon lost in
+the mammal, and its function in the skull is different
+from the corresponding bone in Pterodactyles.</p>
+
+
+<h4>BONES ABOUT THE EYES</h4>
+
+<div class="figcenter" style="width: 492px;">
+<a name="Fig_21" id="Fig_21"></a>
+<span class="caption">FIG. 21. &nbsp;  UPPER SURFACE OF SKULL OF THE HERON</span>
+<p class="center">Compared with the same aspect of the skull of Rhamphorhynchus</p>
+<img src="images/i_082.jpg" width="492" height="480" alt="FIG. 21." title="FIG. 21." />
+</div>
+
+
+<p>The third opening in the side of the head, counting
+from before backward, is the orbit of the eye. In this
+vacuity is often seen the sclerotic circle of overlapping
+bones formed in the external membrane of the eye,
+like those in nocturnal birds and some reptiles. The
+<span class='pagenum'><a name="Page_66" id="Page_66">[Pg 66]</a></span>
+eye hole varies in form from an inverted pear-shape
+to an oblique or transverse oval, or a nearly circular
+outline. It is margined by the frontal bone above;
+the tear bone or lachrymal, and the malar or cheek
+bone in front; while the bones behind appear to be
+the quadrato-jugal and post-frontal bones, though the
+bones about the eye are somewhat differently arranged
+in different genera.</p>
+
+<p>The eyes were frequently, if not always, in contact
+with the anterior walls of the brain case, as in many
+birds, and are always far back in the side of the head.
+In Dimorphodon they are in front of the articulation
+of the lower jaw; in Rhamphorhynchus, above that
+articulation; while in Ornithostoma they are behind
+the articulation for the jaw. This change is governed
+by the position of the quadrate bone, which is vertical
+in the Lias genus, inclined obliquely forward in the
+fossils from the Oolites, and so much inclined in the
+Chalk fossil that the small orbit is thrown relatively
+further back.</p>
+
+<p>Thus far the chief difference in the Pterodactyle
+skull from that of a bird is in the way in which the
+malar arch is prolonged backward on each side. It is
+a slender bar of bone in birds, without contributing
+ascending processes to border vacuities in the side
+of the face, while in these fossil animals the lateral
+openings are partly separated by the ascending processes
+of these bones. This divergence from birds,
+in the malar bone entering the orbit of the eye
+is approximated to among reptiles and mammals,
+though the conditions, and perhaps the presence of a
+bone like the post-orbital bone, are paralleled only
+among Reptiles. The Pterodactyles differ among
+themselves enough for the head to make a near
+<span class='pagenum'><a name="Page_67" id="Page_67">[Pg 67]</a></span>
+approach to Reptiles in Dimorphodon, and to Birds
+in Pterodactylus. In the Ground Hornbill and the
+Shoebill the lachrymal bones in front of the orbits
+of the eyes grow down to meet the malar bars without
+uniting with them. The post-frontal region also
+is prolonged downward almost as far as the malar
+bar, as though to show that a bird might have its
+orbital circle formed in the same way and by the
+same bones as in Pterodactylus. Cretaceous Ornithosaurs
+sometimes differ from birds apparently in admitting
+the quadrato-jugal bone into the orbit. It
+then becomes an expanded plate, instead of a slender
+bar as in all birds.</p>
+
+
+<h4>THE TEMPORAL FOSSA</h4>
+
+<p>A fourth vacuity is known as the temporal fossa.
+When the skull of such a mammal as a Rabbit, or
+Sheep, is seen from above, there is a vacuity behind
+the orbits for the eyes, which in life is occupied by
+the muscles which work the lower jaw. It is made
+by the malar bone extending from the back of the
+orbit and the process of bone, called the zygomatic
+process, extending forward from the articulation of
+the jaw, which arches out to meet the malar bone.</p>
+
+<p>In birds there is no conspicuous temporal fossa,
+because the malar bar is a slender rod of bone in a
+line with the lower end of the quadrate bone.</p>
+
+<p>Reptile skulls have sometimes one temporal vacuity
+on each side, as among tortoises, formed by a single
+lateral bar. These vacuities, which correspond to
+those of mammals in position, are seen from the top
+of the head, as lateral vacuities behind the orbits
+of the eyes, and are termed superior temporal vacuities.
+In addition to these there is often in other
+<span class='pagenum'><a name="Page_68" id="Page_68">[Pg 68]</a></span>
+reptiles a lateral opening behind the eye, termed
+the inferior temporal vacuity, seen in Crocodiles, in
+Hatteria, and in Lizards; and in such skulls there are
+two temporal bars seen in side view, distinguished as
+superior and inferior. The superior arch always includes
+the squamosal bone, which is at the back
+of the single bar in mammals. The lower arch
+includes the malar bone, which is in front in the single
+arch of mammals. The circumstance that both these
+arches are connected with the quadrate bone makes
+the double temporal arch eminently reptilian.</p>
+
+<p>In Ornithosaurs the lateral temporal vacuity varies
+from a typically reptilian condition to one which,
+without becoming avian, approaches the bird type. In
+skulls from the Lias, Dimorphodon and Campylognathus,
+there is a close parallel to the living New
+Zealand reptile Hatteria, in the vertical position
+of the quadrate bone and in the large size of the
+vacuity behind and below the eye, which extends
+nearly the height of the skull. In the species of the
+genus Pterodactylus, the forward inclination of the
+quadrate bone recalls the Curlew, Snipe, and other
+birds. The back of the head is rounded, and the
+squamosal bone, which appears to enter into the
+wall of the brain case as in birds and mammals,
+is produced more outward than in birds, but less
+than in mammals, so as to contribute a little to
+the arch which is in the position of the post-frontal
+bone of reptiles. It is triangular, and stretches from
+the outer angle of the frontal bone at the back of the
+orbit to the squamosal behind, where it also meets
+the quadrate bone. Its third lower branch meets the
+quadratojugal, which rests upon the front of the quadrate
+bone, as in Iguanodon, and is unlike Dimorphodon
+<span class='pagenum'><a name="Page_69" id="Page_69">[Pg 69]</a></span>
+in its connexions. In that genus the supra-temporal
+bone, or post-orbital bone, appears to rest upon the
+post-frontal and connect it with the quadrato-jugal.
+In Dimorphodon the malar bone is entirely removed
+from the quadrate, but in Pterodactylus it meets its
+articular end. Between the post-frontal bone above
+and the quadrato-jugal bone below is a small lunate
+opening, which represents the lateral temporal
+vacuity; and so far, this is a reptilian character.
+But if the thin post-frontal bone were absorbed,
+Pterodactylus would resemble birds. There is no
+evidence that the quadrate bone is free in any
+Ornithosaurs, as it is in all birds, while in Dimorphodon
+it unites by suture with the squamosal bone.
+In Ornithostoma the lateral temporal vacuity is little
+more than a slit between the quadrate bone below,
+the quadrato-jugal in front, and what may be the
+post-frontal bone behind (see <a href="#Fig_2">Fig. 2, p. 12</a>).</p>
+
+
+<h4>BONES ABOUT THE BRAIN</h4>
+
+<p>The bones containing the brain appear to be the
+same as form the brain case in birds. The form of
+the back of the skull varies in two ways. First it
+may be flat above and flat at the back, when the
+back of the head appears to be square. This condition
+is seen in all the long-tailed genera, such as
+Campylognathus from the Lias and Rhamphorhynchus,
+and is associated with a high position for the
+upper temporal bar. Secondly, the back of the head
+may be rounded convexly, both above and behind.
+That condition is seen in the short-tailed genera,
+such as Pterodactylus. But in the large Cretaceous
+types, such as Ornithocheirus and Ornithostoma,
+the superior longitudinal ridge which runs back in
+<span class='pagenum'><a name="Page_70" id="Page_70">[Pg 70]</a></span>
+the middle line of the face becomes elevated and
+compressed from side to side at the back of the head
+as a narrow deep crest, prolonged backward over the
+neck vertebr&aelig; for some inches of length. All these
+three types are paralleled more or less in birds which
+have the back of the head square like the Heron, or
+rounded like the Woodpecker; or crested, though the
+crest of the Cormorant is not quite identical with
+Ornithocheirus, being a distinct bone at the back of
+the head in the bird which never blends with the
+skull. In so far as the crest is reptilian it suggests
+the remarkable crest of the Chameleon. In the
+structure of the back of the skull the bones are a
+modification of the reptilian type of Hatteria in
+the Lias genus Campylognathus, but the reptilian
+characters appear to be lost in the less perfectly
+preserved skulls of Cretaceous genera.</p>
+
+<p>The palate is well known in the chief groups of
+Ornithosaurs, such as Campylognathus, Scaphognathus,
+and Cycnorhamphus.</p>
+
+<p>Mr. E. T. Newton, <small>F.R.S.</small>, has shown that in the
+English skull from the Lias of Whitby, the forms of
+the bones are similar to the palate in birds and unlike
+the conditions in reptiles. There is one feature, however,
+which may indicate a resemblance to Dicynodon
+and other fossil reptiles from South Africa. A
+slender bone extends from the base of the brain case,
+named the basi-sphenoid bone, outward and forward
+to the inner margin of the quadrate bone (<a href="#Fig_22">Fig. 22</a>).
+A bone is found thus placed in those South African
+Reptiles, which show many resemblances to the Monotreme
+and Marsupial Mammals. It is not an ordinary
+element of the skeleton and is unknown in living
+animals of any kind in that position. It has been
+<span class='pagenum'><a name="Page_71" id="Page_71">[Pg 71]</a></span>
+thought possible that it may represent one of the
+bones which among mammals are diminutive and
+are included in the internal ear. The resemblance
+may have some interest hereafter, as helping to show
+that certain affinities of the Ornithosaurs may lie
+outside the groups of existing reptiles. Instead of
+being directed transversely outward, as in the palatal
+region of <i>Dicynodon lacerticeps</i>, they diverge outward
+and forward to the inner border of the articulation
+for the lower jaw which is upon the quadrate
+bone.</p>
+
+
+<div class="figcenter" style="width: 635px;">
+<a name="Fig_22" id="Fig_22"></a>
+<span class="caption">FIG. 22</span>
+<img src="images/i_088.jpg" width="635" height="480" alt="FIG. 22" title="FIG. 22" />
+</div>
+
+
+
+<h4>BONES OF THE PALATE</h4>
+
+<p>There is a pair of bones which extend forward
+from these inner articular borders of the quadrate
+bones, and converge in a long <b>V</b>-shape till they
+merge in the hard palate formed by the bones of the
+front of the beak, named intermaxillary and maxillary
+bones. The limits of the bones of the palate are<span class='pagenum'><a name="Page_72" id="Page_72">[Pg 72]</a></span>
+not distinct, but there can be no doubt that the front
+of the <b>V</b> is the bone named vomer, that the palatine
+bones are at its sides, and that its hinder parts are
+the pterygoid bones as in birds. There is a long,
+wide, four-sided, open space in the middle of the
+palate, between the vomer and the basi-sphenoid
+bone, unlike anything in birds or other animals.</p>
+
+<p>Professor Marsh, in a figure of the palate in the
+great skull of the toothless Pterodactyle named Ornithostoma
+(Pteranodon), from the Chalk of Kansas,
+found a large oval vacuity in this region of the palate.
+In that genus the pterygoid bones meet each other
+between the quadrate bones as in Dicynodon (<a href="#Fig_73">Fig. 73,
+p. 182</a>). Hence the great palatal vacuity here seen in
+the Ornithosaur is paralleled by the small vacuity in
+the South African reptile, which is sometimes distinct
+and sometimes partly separated from the anterior
+part of the vacuity which forms the openings of the
+nostrils on the palate.</p>
+
+<p>The Solenhofen skulls which give any evidence of
+the palate are exposed in side view only, and the
+bones, imperfectly seen through the lateral vacuities,
+are displaced by crushing. They include long strips
+like the vomerine bones in the Lias fossil, and they
+diverge in the same way as they extend back to the
+quadrate bones. The oblique division into vomer in
+front and pterygoid bone behind is shown by Goldfuss
+in his original figure of Scaphognathus. Thus
+there is some reason for believing that all Ornithosaurs
+have the palate formed upon the same general plan,
+which is on the whole peculiar to the group, especially
+in not having the palatal openings of the nares
+divided in the middle line. It would appear probable
+that the short-tailed animals have the pterygoid bones<span class='pagenum'><a name="Page_73" id="Page_73">[Pg 73]</a></span>
+meeting in the middle line and triangular; and that
+they are slender rods entirely separate from each
+other in the long-tailed genera.</p>
+
+
+<h4>THE TEETH</h4>
+
+<p>The teeth are all of pointed, elongated shape, without
+distinction into the kinds seen in most mammals
+and named incisors, canines, and grinders. They are
+organs for grasping, like the teeth of the fish-eating
+Crocodile of India, and are not unlike the simple teeth
+of some Porpoises. They are often implanted in
+oblique oval sockets with raised borders, usually at
+some distance apart from each other, and have the
+crown pointed, flattened more on the outer side than
+on the inner side, usually directed forward and curved
+inward. As in many extinct animals allied to existing
+reptiles, the teeth are reproduced by germs, which
+originate on the inner side of the root and grow till
+they gradually absorb the substance of the old tooth,
+forming a new one in its place. Frequently in Solenhofen
+genera, like Scaphognathus and Pterodactylus,
+the successional tooth is seen in the jaw on the hinder
+border of the tooth in use. There is some variation
+in the character of bluntness or sharpness of the
+crowns in the different genera, and in their size.</p>
+
+<p>The name Dimorphodon, given to the animal from
+the Lias of Lyme Regis, expresses the fact that the
+teeth are of two kinds. In the front of the jaw three or
+four large long teeth are found in the intermaxillary
+bone on each side, as in some Plesiosaurs, while the
+teeth found further back in the maxillary bone are
+smaller, and directed more vertically downward. This
+difference is more marked in the lower jaw than in the
+upper jaw. In Rhamphorhynchus the teeth are all<span class='pagenum'><a name="Page_74" id="Page_74">[Pg 74]</a></span>
+relatively long and large, and directed obliquely
+forward, but absent from the extremities of the beak,
+as in the German genus from the Lias named Dorygnathus,
+in which the bone of the lower jaw (which
+alone is known) terminates in a compressed spear.
+In Scaphognathus the teeth are few, more vertical,
+and do not extend backward so far as in Rhamphorhynchus,
+but are carried forward to the extremity of
+the blunt, deep jaw.</p>
+
+<p>In the short-tailed Pterodactyles the teeth are
+smaller, shorter, wider at the base of the crown,
+closer together, and do not extend so far backward
+in the jaw. In Ornithocheirus two teeth always
+project forward from the front of the jaw. Ornithostoma
+is toothless.</p>
+
+
+<h4>SUPPOSED HORNY BEAK</h4>
+
+<p>Sometimes a horny covering has been suggested
+for the beak, like that seen in birds or turtles, but no
+such structure has been preserved, even in the Solenhofen
+Slate, in which such a structure would seem as
+likely to be preserved as a wing membrane, though
+there is one doubtful exception. There are marks of
+fine blood vessels on some of the jaws, indicating a
+tough covering to the bone. In Rhamphorhynchus
+the jaws appear to gape towards their extremities as
+though the interspace had originally been occupied
+by organic substance like a horny beak.</p>
+
+
+<h4>LOWER JAW</h4>
+
+<p>The lower jaw varies in relative length with the
+vertical or horizontal position of the quadrate bone in
+the skull. In Dimorphodon the jaw is as long as the
+skull; but in the genera from the Oolitic rocks the<span class='pagenum'><a name="Page_75" id="Page_75">[Pg 75]</a></span>
+mandible is somewhat shorter, and in Ornithostoma
+the discrepancy reaches its maximum. The hinder
+part of the jaw is never prolonged backward much
+beyond the articulation, differing in this respect from
+Crocodiles and Plesiosaurs.</p>
+
+<p>The depth of the jaw varies. It is slender in
+Pterodactylus, and is probably stronger relatively to
+the skull in Scaphognathus than in any other form.
+It fits between the teeth and bones of the alveolar
+border in the skull, in all the genera. In Dimorphodon
+its hinder border is partly covered by the
+descending edge of the malar process which these
+animals develop in common with some Dinosaurs,
+and some Anomodont reptiles, and many of the lower
+mammals. In this hinder region the lower jaw is
+sometimes perforated, in the same way as in Crocodiles.
+That condition is observed in Dimorphodon,
+but is not found in Pterodactylus. The lower jaw is
+always composite, being formed by several bones, as
+among reptiles and birds. The teeth are in the
+dentary bone or bones, and these bones are almost
+always blended as in most birds and Turtles, and not
+separate from each other as among Crocodiles, Lizards,
+and Serpents.</p>
+
+<p>An interesting contour for the lower border of the
+jaw is seen in Ornithostoma, as made known in
+figures of American examples by Professors Marsh
+and Williston. It deepens as it extends backwards
+for two-thirds its length, stops at an angle, and then
+the depth diminishes to the articulation with the
+skull. This angle of the lower jaw is a characteristic
+feature of the jaws of Mammals. It is seen in the
+monotreme Echidna, and is characteristic of some
+Theriodont Reptiles from South Africa, which in
+<span class='pagenum'><a name="Page_76" id="Page_76">[Pg 76]</a></span>
+many ways resemble Mammals. The character is
+not seen in the jaws of specimens from the Oolitic
+rocks, but is developed in the toothed Ornithocheirus
+from the Cambridge Greensand, and is absent from
+the jaws of existing reptiles and birds.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_23" id="Fig_23"></a>
+<span class="caption">FIG. 23. &nbsp; COMPARISON OF THE LOWER JAW IN
+ECHIDNA AND ORNITHOSTOMA</span>
+<img src="images/i_093.jpg" width="640" height="417" alt="FIG. 23." title="FIG. 23." />
+</div>
+
+
+<h4>SUMMARY OF CHARACTERS OF THE HEAD</h4>
+
+<p>Taken as a whole, the head differs from other types
+of animals in a blending of characters which at the
+present day are found among Birds and Reptiles, with
+some structures which occur in extinct groups of
+animals with similar affinities, and perhaps a slight
+indication of features common to the lowest mammals.
+It is chiefly upon the head that the diverse views of
+earlier writers have been based.  Cuvier was impressed
+with the reptilian aspect of the teeth; but in
+later times discoveries were made of Birds with teeth&mdash;Arch&aelig;opteryx,
+Ichthyornis, Hesperornis. The teeth
+are quite reptilian, being not unlike miniature teeth
+<span class='pagenum'><a name="Page_77" id="Page_77">[Pg 77]</a></span>
+of Mosasaurus.  If those birds had been found prior
+to the discovery of Pterodactyles, the teeth might
+have been regarded as a link with the more ancient
+birds, rather than a crucial difference between birds
+and reptiles.</p>
+
+<p>All the specimens show a lateral temporal hole in
+the bones behind the eye, and this is found in no
+bird or mammal, and is typical of such reptiles as
+Hatteria.  The quadrate bone may not be so decisive
+as Cuvier thought it to be, for its form is not unlike
+the quadrate of a bird, and different, so far as I have
+seen, from that of living reptiles.  This region of the
+head is reptilian, and if it occurred in a bird the character
+would be as astonishing as was the discovery of
+teeth in extinct birds.  These characters of the head
+are also found in fossil animals named Dinosaurs, in
+association with many resemblances to birds in their
+bones.</p>
+
+<p>The palate might conceivably be derived from
+that of Hatteria by enlarging the small opening in
+the middle line in that reptile till it extended forward
+between the vomera; but it is more easily compared
+with a bird, which the animal resembles in its beak,
+and in the position of the nares.  Excepting certain
+Lizards, all true existing Reptiles have the nostrils
+far forward and bordered by two premaxillary bones
+instead of one intermaxillary, as in Birds and Ornithosaurs.
+If nothing were known of the animal but
+its head bones, it would be placed between Reptiles
+and Birds.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_78" id="Page_78">[Pg 78]</a></span></p>
+<h2><a name="CHAPTER_IX" id="CHAPTER_IX"></a><small>CHAPTER IX</small><br /><br />
+
+THE BACKBONE, OR VERTEBRAL
+COLUMN</h2>
+
+
+<p>The backbone is a more deep-seated part of the
+skeleton than the head. It is more protected
+by its position, and has less varied functions to perform.
+Therefore it varies less in distinctive character
+within the limits of each of the classes of vertebrate
+animals than either the head or limbs. It is divided
+into neck bones, the cervical vertebr&aelig;; back bones,
+the dorsal vertebr&aelig;; loin bones, the lumbar vertebr&aelig;;
+the sacrum, or sacral vertebr&aelig;, which support the
+hind limbs; and the tail. Of these parts the tail is
+the least important, though it reaches a length in
+existing reptiles which sometimes exceeds the whole
+of the remainder of the body, and includes hundreds
+of vertebr&aelig;. It attains its maximum among serpents
+and lizards. In frogs it is practically absent. In
+some of the higher mammals it is a rudiment, which
+does not extend beyond the soft parts of the body.</p>
+
+
+<h4>THE NECK</h4>
+
+<p>The neck is more liable to vary than the back, with
+the habit of life of the animal. And although
+mammals almost always preserve the same number
+<span class='pagenum'><a name="Page_79" id="Page_79">[Pg 79]</a></span>
+of seven bones in the neck, the bones vary in length
+between the short condition of the porpoise, in
+which the neck is almost lost, and the long bones
+which form the neck of the Llama, though even these
+may be exceeded by some fossil reptiles like Tanystroph&#339;us.
+In many mammals the neck bones do
+not differ in length or size from those of the back.
+In others, like the Horse and Ox, they are much
+broader and larger.</p>
+
+<p>There is the same sort of variation in the bones of
+the neck among birds, some being slender like the
+Heron, others broad like the Swan.  But there is also
+a singular variation in number of vertebral bones
+in a bird's neck.  At fewest there are nine, which
+equals the exceptionally large number found among
+mammals in the neck of one of the Sloths.  Usually
+birds have ten to fifteen cervical vertebr&aelig;, and in the
+Swan there are twenty-three.  Most of the neck bones
+of birds are relatively long, and the length of the neck
+is often greater than the remainder of the vertebral
+column.</p>
+
+<p>Reptiles usually have short necks.  The common
+Turtle has eight bones in the neck, ten in the back.
+The two regions are sharply defined by the dorsal
+shield.  Their articular ends are sometimes cupped in
+front, in the neck, sometimes cupped behind, or convex
+at both ends, or even flattened, or the articulation
+may be made exceptionally by the neural arch alone.
+Nine is the largest number of neck bones in existing
+Lizards, and there are usually nine in Crocodiles; so
+that reptiles closely approach mammals in number of
+the neck bones.  It is remarkable that the maximum
+number in a mammal and in living reptiles should
+coincide with the minimum number in birds.  Therefore
+<span class='pagenum'><a name="Page_80" id="Page_80">[Pg 80]</a></span>
+the number of cervical vertebr&aelig; as an attribute
+of Mammal, Bird, or Reptile, can only be important
+from its constancy.</p>
+
+<p>German naturalists affirm on clear evidence that
+the Solenhofen Pterodactyles have seven cervical vertebr&aelig;.
+In many specimens there can be no doubt
+about the number, because the neck bones are easily
+distinguished from those of the back by their size;
+but the number is not always easy to count.</p>
+
+<p>As in Birds, the first vertebra, or atlas, in Pterodactyles
+is extremely short, and is generally&mdash;if not
+always&mdash;blended with the much longer second vertebra,
+named the axis.  The front of the atlas forms
+a small rounded cup to articulate with the rounded
+ball of the basioccipital bone at the back of the skull.
+The third and fourth vertebr&aelig; are longer, but the
+length visibly shortens in the sixth and seventh.</p>
+
+<p>Sometimes the vertebr&aelig; are slender and devoid of
+strong spinous processes.  This is the condition in
+the little <i>Pterodactylus longirostris</i> and in the comparatively
+large <i>Cycnorhamphus Fraasii</i>, in which
+there is a slight median ridge along the upper surface
+of the arch of the vertebra. This condition is paralleled
+in birds with long necks, especially wading
+birds such as the Heron.  Other Ornithosaurs, such
+as Ornithocheirus from the Cretaceous rocks, have the
+neck much more massive.  The vertebr&aelig; are flattened
+on the under side.  The arch above the nervous
+matter of the spinal cord has a more or less considerable
+transverse expansion, and may even be as
+wide as long.  These vertebr&aelig; have proportions and
+form such as may be seen in Vultures or in the
+Swan.  In either case the form of the neck bones
+is more or less bird-like, and the neural spine may
+<span class='pagenum'><a name="Page_81" id="Page_81">[Pg 81]</a></span>
+be elevated, especially in Pterodactyles with long
+tails.</p>
+
+<p>One of the most distinctive features of the neck
+bones of a bird is the way in which the cervical ribs
+are blended with the vertebr&aelig;. They are small, and
+each is often prolonged in a needle-like rod at the
+side of the neck bone.</p>
+
+<p>In Ornithocheirus the cervical rib similarly blends
+with the vertebra by two articulations, as in mammals,
+so that it might escape notice but for the
+channel of a blood vessel which is thus inclosed.
+In several of the older Pterodactyles from Solenhofen
+the ribs of the neck vertebr&aelig; remain separated,
+as in a Crocodile, though still bird-like in their
+form, anterior position, and mode of attachment. In
+Terrapins and Tortoises the long neck vertebr&aelig; have
+no cervical ribs.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_24" id="Fig_24"></a>
+<span class="caption">FIG. 24 &nbsp; UNITED ATLAS AND AXIS OF ORNITHOCHEIRUS</span>
+<p class="center">(Cambridge Greensand)</p>
+<img src="images/i_098.jpg" width="640" height="337" alt="FIG. 24" title="FIG. 24" />
+</div>
+
+<p>The articular surfaces between the bodies of the
+vertebr&aelig;, in the neck, are transversely oval. The middle
+part of this articular joint is made by the body of
+the vertebra; its outer parts are in the neural arch.
+In front this surface is a hollow channel, often more
+depressed than in any other animals. The corresponding
+surface behind is convex, with a process on
+<span class='pagenum'><a name="Page_82" id="Page_82">[Pg 82]</a></span>
+each side at its lower outer angles (<a href="#Fig_25">Fig. 25</a>). It is a
+modification of the cup-and-ball form of vertebral
+articulation, which at the present day is eminently
+reptilian. Serpents and Crocodiles have the articulations
+similarly vertical, but in both the form of the
+articulation is a circle. In Lizards the articular cup is
+usually rather wider than deep, when the cup and
+ball are developed in the vertebr&aelig;; it differs from
+the vertical condition in pterodactyles in being oblique
+and much narrower from side to side. Only among
+Crocodiles and Hatteria is there a double articulation
+for the cervical rib, though in neither order have rib
+or vertebra in the neck the bird-like proportions
+which are usual in these animals. Pterodactyles show
+no resemblance to birds in this vertebral articulation.
+A Bird has the corresponding surface concave from
+side to side in front, but it is also convex from above
+downward, producing what is known as the saddle-shaped
+form which is peculiarly avian, being found
+in existing birds except in part of the back in Penguins.
+It is faintly approximated to in one or two
+neck vertebr&aelig; in man. Professor Williston remarks
+that in the toothless Pterodactyles of Kansas the
+hinder ball of the vertebral articulation is continued
+downward and outward as a concave articulation
+upon the processes at its outer corners. There are
+no mammals with a cup-and-ball articulation between
+the vertebr&aelig;, so that for what it is worth the character
+now described in Ornithosaurs is reptilian, when
+judged by comparison with existing animals.</p>
+
+<p>Low down on each side of the vertebra, at the
+junction of its body with the neural arch, is a large
+ovate foramen, transversely elongated, and often a
+little impressed at the border, which is the entrance
+<span class='pagenum'><a name="Page_83" id="Page_83">[Pg 83]</a></span>
+of the air cell into the bone. These foramina are
+often one-third of the length of the neck vertebr&aelig;
+in specimens from the Cambridge Greensand, where
+the neck bones vary from three-quarters of an inch
+to about two and a half inches in length, and in
+extreme forms are as wide as long. The width of
+the interspace between the foramina is one-half the
+width of the vertebr&aelig;, though this character varies
+with different genera and species. Several species
+from the Solenhofen Slate have the neck long and
+slender, on the type of the Flamingo. In others the
+neck is thick and short&mdash;in the <i>Scaphognathus crassirostris</i>
+and <i>Pterodactylus spectabilis</i>. Some genera
+with slender necks have the bones preserved with a
+curved contour, such as might suggest a neck carried
+like that of a Llama or a Camel. The neck is occasionally
+preserved in a curve like a capital <b>S</b>, as
+though about to be darted forward like that of a
+bird in the act of striking its prey. The genera of
+Pterodactyles with short necks may have had as great
+mobility of neck as is found among birds named
+Ducks and Divers; but those Pterodactyles with
+stout necks, such as Dimorphodon and Ornithocheirus,
+in which the vertebr&aelig; are large, appear to
+<span class='pagenum'><a name="Page_84" id="Page_84">[Pg 84]</a></span>
+have been built more for strength than activity, and
+the neck bones have been chiefly concerned in the
+muscular effort to use the fighting power of the jaws
+in the best way.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_25" id="Fig_25"></a>
+<span class="caption">FIG. 25. &nbsp;  CERVICAL VERTEBRA OF ORNITHOCHEIRUS</span>
+<p class="center">From the Cambridge Greensand</p>
+<img src="images/i_100.jpg" width="640" height="276" alt="FIG. 25." title="FIG. 25." />
+</div>
+
+
+<h4>THE BACK</h4>
+
+<p>The region of the back in a Pterodactyle is short
+as compared with the neck, and relatively is never
+longer than the corresponding region in a bird. The
+shortness results partly from the short length of the
+vertebr&aelig;, each of which is about as long as wide.
+There is also a moderate number of bones in the
+back. In most skeletons from Solenhofen these
+vertebr&aelig; between the neck and girdle of hip bones
+number from twelve to sixteen. They have a general
+resemblance in form to the dorsal vertebr&aelig; in birds.
+The greatest number of such vertebr&aelig; in birds is
+eleven. The number is small because some of the
+later vertebr&aelig; in birds are overlapped by the bones
+of the hip girdle, which extend forward and cover
+them at the sides, so that they become blended with
+the sacrum. This region of the skeleton in the
+Dimorphodon from the Lias is remarkable for the
+length of the median process, named the neural
+spine, which is prolonged upward like the spines of
+the early dorsal vertebr&aelig; of Horses, Deer, and other
+mammals. In this character they differ from living
+reptiles, and parallel some Dinosaurs from the Weald.
+The bones of the back in Ornithocheirus from the
+Cambridge Greensand show the under side to be well
+rounded, so that the articular surfaces between the
+vertebr&aelig;, though still rather wider than deep, are
+much less depressed than in the region of the neck.
+The neural canal for the spinal cord has become
+<span class='pagenum'><a name="Page_85" id="Page_85">[Pg 85]</a></span>
+larger and higher, and the sides of the bone are
+somewhat compressed. Strong transverse processes
+for the support of the ribs are elevated above the
+level of the neural canal, at the sides of vertebr&aelig;
+compressed on the under sides, and directed outward.
+Between these lateral horizontal platforms
+is the compressed median neural spine, which varies
+in vertical height. The articulation of the ribs is not
+seen clearly. Isolated ribs from the Stonesfield Slate
+have double-headed dorsal ribs, like those of birds.
+In some specimens from the Solenhofen Slate like
+the Scaphognathus, in the University Museum at
+Bonn, dorsal ribs appear to be attached by a notch
+in the transverse process of the dorsal vertebra, which
+resembles the condition in Crocodiles. Variations in
+the mode of attachment of ribs among mammals
+may show that character to be of subordinate importance.
+Von Meyer has described the first pair
+of ribs as frequently larger than the others, and
+there appear in Rhamphorhynchus to be examples
+preserved of the sternal ribs, which connect the
+dorsal ribs with the sternum. Six pairs have been
+counted. A more interesting feature in the ribs
+consists in the presence behind the sternum, which
+is shorter than the corresponding bone in most birds,
+of median sternal ribs. They are slender <b>V</b>-shaped
+bones in the middle line of the abdomen, which
+overlapped the ends of the dorsal ribs like the
+similar sternal bones of reptiles. Such structures
+are unknown among Birds and Mammals. There is
+no trace in the dorsal ribs of the claw-like process,
+which extends laterally from rib to rib as a marked
+feature in many birds. Its presence or absence may
+not be important, because it is represented by fibro-cartilage
+<span class='pagenum'><a name="Page_86" id="Page_86">[Pg 86]</a></span>
+in the ribs of crocodiles, and may be a small
+cartilage near the head of the rib in serpents, and is
+only ossified in some ribs of the New Zealand reptile
+Hatteria. So that it might have been present in a
+fossil animal without being ossified and preserved.
+Although the structure is associated with birds, it
+is possibly also represented by the great bony plates
+which cover the ribs in Chelonians, and combine to
+form the shield which covers the turtle's back. The
+structure is as characteristic of reptiles as of birds,
+but is not necessarily associated with either.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_26" id="Fig_26"></a>
+<span class="caption">FIG. 26</span>
+<img src="images/i_103.jpg" width="640" height="441" alt="FIG. 26" title="FIG. 26" />
+<p class="center">The upper figures show the side and back of a dorsal vertebra of
+Ornithocheirus compared with corresponding views of the
+side and back of a dorsal vertebra of a Crocodile</p>
+</div>
+
+<p>There are two remarkable modifications of the
+early dorsal vertebr&aelig; in some of the Cretaceous
+Pterodactyles. First, in the genus Ornithodesmus
+from the Weald the early dorsal vertebr&aelig; are blended
+together into a continuous mass, like that which is
+found in the corresponding region of the living
+Frigate-bird, only more consolidated, and similar to
+<span class='pagenum'><a name="Page_87" id="Page_87">[Pg 87]</a></span>
+that consolidated structure found behind the dorsal
+vertebr&aelig;, known as the sacrum, made by the blending
+of the vertebr&aelig; into a solid mass which supports
+the hip bones. Secondly, in some of the Cretaceous
+genera of Pterodactyles of Europe and America the
+vertebr&aelig; in the front part of the back are similarly
+blended, but their union is less complete; and in
+genera Ornithocheirus and Ornithostoma&mdash;the former
+chiefly English, the latter chiefly American&mdash;the
+sides of the neural spines are flattened to form an
+oval articular surface on each side, which gives
+attachment to the flattened ends of their shoulder-blade
+bones named the scapul&aelig;. This condition is
+found in no other animals. Three vertebr&aelig; appear
+to have their neural arches thus united together.
+The structure so formed may be named the notarium
+to distinguish it from the sacrum.</p>
+
+
+<h4>SACRUM</h4>
+
+<p>For some mysterious reason the part of the backbone
+which lies between the bones of the hips and
+supports them is termed the sacrum. Among living
+reptiles the number of vertebr&aelig; in this region is
+usually two, as in lizards and crocodiles. There are
+other groups of fossil reptiles in which the number
+of sacral vertebr&aelig; is in some cases less and in other
+cases more. There is, perhaps, no group in which the
+sacrum makes a nearer approach to that of birds
+than is found among these Pterodactyles, although
+there are more sacral vertebr&aelig; in some Dinosaurs.
+In birds the sacral vertebr&aelig; number from five to
+twenty-two. In bats the number is from five to six.
+In some Solenhofen species, such as <i>Pterodactylus
+dubius</i> and <i>P. Kochi</i> and <i>P. grandipelvis</i>, the number
+<span class='pagenum'><a name="Page_88" id="Page_88">[Pg 88]</a></span>
+is usually five or six. The vertebr&aelig; are completely
+blended. The pneumatic foramina in the sacrum, so
+far as they have been observed, are on the under
+sides of the transverse processes;
+while in the corresponding notarial
+structure in the shoulder
+girdle the foramina are in front
+of the transverse processes. Almost
+any placental mammal in
+which the vertebr&aelig; of the sacral
+region are anchylosed together
+has a similar sacrum, which
+differs from that of birds in the
+more complete individuality of
+the constituent bones remaining
+evident. The transverse processes
+in front of the sacrum are
+wider than in its hinder part; so
+that the pelvic bones which are
+attached to it converge as they
+extend backward, as among
+mammals. The bodies of the vertebr&aelig; forming the
+sacrum are similar in length to those of the back.
+Each transverse process is given off opposite the
+body of its own vertebra, but from a lower lateral
+position than in the region of the back, in which the
+vertebr&aelig; are free.</p>
+
+<div class="figcenter" style="width: 406px;">
+<a name="Fig_27" id="Fig_27"></a>
+<span class="caption">FIG. 27. &nbsp; SACRUM OF RHAMPHORHYNCHUS</span>
+<img src="images/i_105.jpg" width="406" height="640" alt="FIG. 27." title="FIG. 27." />
+<p class="center">Showing the complete blending
+of the vertebr&aelig; and ribs as
+in a bird, with the well-defined
+Iliac bones, produced chiefly
+in front of the acetabulum for
+the head of the femur.</p>
+</div>
+
+
+<p>The hip bones are closely united with the sacrum
+by bony union, and rarely appear to come away from
+the sacral vertebr&aelig;, as among mammals and reptiles,
+though this happens with the Lias Pterodactyles. In
+the Stonesfield Slate and Solenhofen Slate the slender
+transverse processes from the vertebr&aelig; blend with the
+ilium of the hip girdle, and form a series of transverse
+<span class='pagenum'><a name="Page_89" id="Page_89">[Pg 89]</a></span>
+foramina on each side of the bodies of the vertebr&aelig;.
+In the Cambridge Greensand genera the part
+of the ilium above the acetabulum for the articular
+head of the femur appears to be always broken away,
+so that the relation of the sacrum to the pelvis has
+not been observed. This character is no mark of
+affinity, but only shows that ossification obliterated
+sutures among these animals in the same way as
+among birds.</p>
+
+<p>The great difference between the sacrum of a
+Pterodactyle and that of a bird has been rendered
+intelligible by the excellent discussion of the sacral
+region in birds made by Professor Huxley. He
+showed that it is only the middle part of the sacrum
+of a chicken which corresponds to the true sacrum of
+a reptile, and comprises the five shortest of the vertebr&aelig;;
+while the four in front correspond to those of
+the lower part of the back, which either bear no ribs
+or very short ribs, and are known as the lumbar
+region in mammals, so that the lower part of the
+back becomes blended with the sacrum, and thus
+reduces the number of dorsal vertebr&aelig;. Similarly
+the five vertebr&aelig; which follow the true sacral vertebr&aelig;
+are originally part of the tail, and have been
+blended with the other vertebr&aelig; in front, in consequence
+of the extension along them of the bird's
+hip bones. This interpretation helps to account for
+the great length of the sacrum in many birds, and
+also explains in part the singular shortness of the
+tail in existing birds. The Ornithosaur sacrum has
+neither the lumbar nor the caudal portions of the
+sacrum of a bird.</p>
+<p><span class='pagenum'><a name="Page_90" id="Page_90">[Pg 90]</a></span></p>
+
+<h4>THE TAIL</h4>
+
+<p>The tail is perhaps the least important part of the
+skeleton, since it varies in character and length in
+different genera. The short tails seen in typical
+pterodactyles include as few as ten vertebr&aelig; in
+<i>Pterodactylus grandipelvis</i> and <i>P. Kochi</i>, and as many
+as fifteen vertebr&aelig; in <i>Pterodactylus longirostris</i>. The
+tails are more like those of mammals than existing
+birds, in which there are usually from six to ten
+vertebr&aelig; terminating in the ploughshare bone. But
+just as some fossil birds, like the Arch&aelig;opteryx, have
+about twenty long and slender vertebr&aelig; in the tail,
+so in the pterodactyle Rhamphorhynchus this region
+becomes greatly extended, and includes from thirty-eight
+to forty vertebr&aelig;. In Dimorphodon the tail
+vertebr&aelig; are slightly fewer. The earliest are very
+short, and then they become elongated to two or
+three times the length of the early tail vertebr&aelig;, and
+finally shorten again towards the extremity of the
+tail, where the bones are very slender. In all long-tailed
+Ornithosaurians the vertebr&aelig; are supported
+and bordered by slender ossified ligaments, which
+extend like threads down the tail, just as they do
+in Rats and many other mammals and in some
+lizards.</p>
+
+<p>Professor Marsh was able to show that the extremity
+of the tail in Rhamphorhynchus sometimes
+expands into a strong terminal caudal membrane of
+four-sided somewhat rhomboidal shape. He regards
+this membrane as having been placed vertically. It
+is supported by delicate processes which represent
+the neural spines of the vertebr&aelig; prolonged upward.
+They are about fifteen in number. A corresponding
+<span class='pagenum'><a name="Page_91" id="Page_91">[Pg 91]</a></span>
+series of spines on the lower border, termed chevron
+bones, equally long, were given off from the junctions
+of the vertebr&aelig; on their under sides, and produced
+downward. This vertical appendage is of some
+interest because its expansion is like the tail of a
+fish. It suggests the possibility of having been used
+in a similar way to the caudal fin as an organ for
+locomotion in water, though it is possible that it may
+have also formed an organ used in flight for steering
+in the air.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_28" id="Fig_28"></a>
+<span class="caption">FIG. 28. &nbsp; EXTREMITY OF THE TAIL OF
+<i>RHAMPHORHYNCHUS PHYLLURUS</i> (<span class="smcap">Marsh</span>)</span>
+<img src="images/i_108.jpg" width="640" height="249" alt="FIG. 28." title="FIG. 28." />
+<p class="center">Showing the processes on the upper and under sides of the vertebr&aelig;
+which make the terminal leaf-like expansion</p>
+</div>
+
+
+<p>The tail vertebr&aelig; from the Cambridge Greensand
+are mostly found isolated or with not more than four
+joints in association. They are very like the slender
+type of neck vertebr&aelig; seen in long-necked pterodactyles,
+but are depressed, and though somewhat
+wider are not unlike the tail vertebr&aelig; of the Rhamphorhynchus.
+The pneumatic foramen in them is a
+mere puncture. They have no transverse processes
+or neural spines, nor indications of ribs, or chevron
+bones.</p>
+
+<p>The hindermost specimens of tail vertebr&aelig; observed
+have the neural arch preserved to the end, as among
+reptiles; whereas in mammals this arch becomes
+lost towards the end of the tail. The processes
+by which the vertebr&aelig; are yoked together are
+<span class='pagenum'><a name="Page_92" id="Page_92">[Pg 92]</a></span>
+small. There is nothing to suggest that the tail was
+long, except the circumstance that the slender caudal
+vertebr&aelig; are almost as long as the stout cervical
+vertebr&aelig; in the same animal. No small caudal
+vertebr&aelig; have ever been found in the Cambridge
+Greensand. The tail is very short, according to
+Professor Williston, in the toothless Ornithostoma
+in the Chalk of Kansas.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_93" id="Page_93">[Pg 93]</a></span></p>
+<h2><a name="CHAPTER_X" id="CHAPTER_X"></a><small>CHAPTER X</small><br /><br />
+
+THE HIP-GIRDLE AND HIND
+LIMB</h2>
+
+
+<p>The bones of the hip-girdle form a basin which
+incloses and protects the abdominal vital organs.
+It consists on each side of a composite bone, the
+unnamed bones&mdash;<i>ossa innominata</i> of the older anatomists&mdash;which
+are each attached to the sacrum on
+their inner side, and on the outer side give attachment
+to the hind limbs. As a rule three bones enter
+into the borders of this cup, termed the acetabulum, in
+which the head of the thigh bone, named the Femur,
+moves with a more or less rotary motion.</p>
+
+<p>There are a few exceptions in this division of the
+cup between three bones, chiefly among Salamanders
+and certain Frogs. In Crocodiles the bone below the
+acetabular cup is not divided into two parts. And
+in certain Plesiosaurs from the Oxford Clay&mdash;Mur&aelig;nosaurus&mdash;the
+actual articulation appears to be made
+by two bones&mdash;the ilium and ischium. The three
+bones which form each side of the pelvis are known
+as the ilium, or hip bone, sometimes termed the aitch
+bone; secondly, the ischium, or sitz bone, being the
+bone by which the body is supported in a sitting
+position; and thirdly the pubis, which is the bone in
+<span class='pagenum'><a name="Page_94" id="Page_94">[Pg 94]</a></span>
+front of the acetabulum. The pubic bones meet in
+the middle line of the body on the under side of the
+pelvis in man, and on each side are partly separated
+from the ischia by a foramen, spoken of as the
+obturator foramen, which in Pterodactyles is minute
+and almost invisible, when it exists.</p>
+
+<p>There is often a fourth bony element in the pelvis.
+In some Salamanders a single cartilage is directed
+forward, and forked in front. According to Professor
+Huxley something of this kind is seen in the Dog.
+The pair of bones which extend forward in front
+of the pelvis in Crocodiles may be of the same kind,
+in which case they should be called prepubic bones.
+But among the lower mammals named marsupials
+a pouch is developed for the protection of the young
+and supported by two slender bones attached to the
+pubes, and these bones have long been known as
+marsupial bones. In a still lower group of mammalia
+named monotremata, which lay eggs, and in many
+ways approximate to reptiles and birds, stronger
+bones are developed on the front edge of the pubes,
+and termed prepubic bones. They do not support a
+marsupium.</p>
+
+<p>Naturalists have been uncertain as to the number
+of bones in the pelvis of Pterodactyles, because the
+bones blend together early in life, as in birds. Some
+follow the Amphibian nomenclature, and unite the
+ischium and pubis into one bone, which is then
+termed ischium, when the prepubis is termed the
+pubis, and regarded as removed from the acetabulum.
+There is no ground for this interpretation, for the
+sutures are clear between the three pelvic bones in
+the acetabulum in some specimens, like <i>Cycnorhamphus
+Fraasii</i>, from Solenhofen, and some examples
+<span class='pagenum'><a name="Page_95" id="Page_95">[Pg 95]</a></span>
+of Ornithocheirus from the Cambridge Greensand.
+Pterodactyles all have prepubic bones, which are
+only known in Ornithorhynchus and Echidna among
+mammals, and are absent from the higher mammals
+and birds. They are unknown in any other existing
+animals, unless present in Crocodiles, in which ischium
+and pubis are always undivided. Therefore it is
+interesting to examine the characters of the Ornithosaurian
+pelvis.</p>
+
+<p>The acetabulum for the head of the femur is imperforate,
+being a simple oval basin, as in Chelonian
+reptiles and the higher Mammals. It never shows
+the mark of the ligamentous attachment to the head
+of the femur, which is seen in Mammals. In Birds
+the acetabulum is perforated, as in many of the fossils
+named Dinosaurs, and in Monotremata.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_29" id="Fig_29"></a>
+<span class="caption">FIG. 29. &nbsp; COMPARISON OF THE LEFT SIDE OF THE
+PELVIS IN A BIRD AND A PTERODACTYLE</span>
+<img src="images/i_112.jpg" width="640" height="259" alt="FIG. 29." title="FIG. 29." />
+</div>
+
+
+<p>Secondly, the ilium is elongated, and extends quite
+as much in front of the acetabulum as behind it.
+The bone is not very deep in this front process.
+Among existing animals this relation of the bone is
+nearer to birds than to any other type, since birds
+alone have the ilium extended from the acetabulum
+in both directions. The form of the Pterodactyle
+ilium is usually that of the embryo bird, and its
+slender processes compare in relative length better
+with those of the unhatched fowl and Apteryx of
+<span class='pagenum'><a name="Page_96" id="Page_96">[Pg 96]</a></span>
+New Zealand than with the plate-like form in adult
+birds.</p>
+
+<p>In mammals the ilium is directed forward, and
+even in the Cape ant-eater Orycteropus there is only
+an inappreciable production of the bone backward
+behind the acetabulum. Among reptiles the general
+position of the acetabulum is at the forward termination
+of the ilium, though the Crocodile has some
+extension of the bone in both directions, without
+forming distinct anterior and posterior processes.
+This anterior and posterior extension of the ilium
+is seen in the Theriodont reptiles of Russia and of
+South Africa, as well as in Dinosaurs.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_30" id="Fig_30"></a>
+<span class="caption">FIG. 30. &nbsp; LEFT PELVIC BONES WITH PREPUBIC BONE IN<br />
+<i>PTERODACTYLUS LONGIROSTRIS</i></span>
+<img src="images/i_113.jpg" width="640" height="195" alt="FIG. 30." title="FIG. 30." />
+</div>
+
+<p>Thirdly, in all pterodactyles the ischium and pubis
+are more or less completely blended into a sheet of
+bone, unbroken by perforation, though there is usually
+a minute vascular foramen; or the lower border may
+be notched between the ischium and the pubis, as
+in some of the Solenhofen species, and the pubis
+does not reach the median line of the body. But
+in Dimorphodon the pelvic sheet of bone is unbroken
+by any notch or perforation. The notch between
+the ischium and pubis is well marked in <i>Pterodactylus
+longirostris</i>, and better marked in <i>Pterodactylus dubius</i>,
+<i>Cycnorhamphus Fraasii</i>, and Rhamphorhynchus. The
+fossil animals which appear to come nearest to the
+Pterodactyles in the structure of the pelvis are
+<span class='pagenum'><a name="Page_97" id="Page_97">[Pg 97]</a></span>
+Theriodonts from the Permian rocks of Russia. The
+type known as Rhopalodon has the ilium less prolonged
+front and back, and is much deeper than in any
+Pterodactyle; but the acetabulum is imperforate, and
+the ischium and pubis are not always completely
+separated from each other by suture. In the pelvis
+referred to the Theriodont Deuterosaurus there is
+some approximation to the pelvis of Rhamphorhynchus
+and of <i>Pterodactylus dubius</i> in the depth
+of the division between the pubis and ischium.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_31" id="Fig_31"></a>
+<span class="caption">FIG. 31 &nbsp; PELVIS AND PREPUBIC BONES OF RHAMPHORHYNCHUS</span>
+<img src="images/i_114.jpg" width="640" height="240" alt="FIG. 31" title="FIG. 31" />
+<p class="center">On the left-hand side the two prepubic bones are separate. On
+the right-hand they are united into a transverse bar which
+overlaps the front of pelvis seen from the under side</p>
+</div>
+
+
+<p>There are three modifications of the Ornithosaurian
+pelvis. First, the type of Rhamphorhynchus,
+in which the pubis and ischium are inclined somewhat
+backward, and in which the two prepubic bones
+are triangular, and are often united together to form
+a transverse bow in front of the pubic region.</p>
+
+<p>Secondly, there is the ordinary form of pelvis in
+which the pubis and ischium usually unite with each
+other down their length, as in Dimorphodon, but
+sometimes, as in <i>Pterodactylus dubius</i>, divide immediately
+below the acetabulum. All these types
+possess the paddle-shaped prepubic bones, which are
+never united in the median line.</p>
+
+<p>Thirdly, there is the cretaceous form indicated by
+<span class='pagenum'><a name="Page_98" id="Page_98">[Pg 98]</a></span>
+Ornithocheirus and Ornithostoma, in which the
+posterior half of the ilium is modified in a singular
+way, since it is more elevated towards the sacrum
+than the anterior half, suggesting the contour of the
+upper border of the ilium in a lizard. Without being
+reptilian&mdash;the anterior prolongation of the bone
+makes that impossible&mdash;it suggests the lizards. This
+type also possesses prepubic bones. They appear,
+according to Professor Williston, to be more like
+the paddle-shaped bones of Pterodactylus than like
+the angular bones in Rhamphorhynchus. The prepubic
+bones are united in the median line as in
+Rhamphorhynchus. But their median union in that
+genus favours the conclusion that the bones were
+united in the median line in all species, though they
+are only co-ossified in these two families.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_32" id="Fig_32"></a>
+<span class="caption">FIG. 32. &nbsp;  THE PELVIC BONES OF AN ALLIGATOR SEEN FROM BELOW</span>
+<img src="images/i_115.jpg" width="640" height="403" alt="FIG. 32." title="FIG. 32." />
+<p class="center">The bones in front are here regarded as prepubic, but are commonly
+named pubic</p>
+</div>
+
+
+<p>This median union of the prepubic bones is a
+difference from those mammals like the Ornithorhynchus
+and Echidna, which approach nearest to
+the Reptilia. In them the prepubic bones have a long
+<span class='pagenum'><a name="Page_99" id="Page_99">[Pg 99]</a></span>
+attachment to the front margin of the pubis, and
+extend their points forward without any tendency
+for the anterior extremities to approximate or unite.
+The marsupial mammals have the same character,
+keeping the marsupial bones completely distinct
+from each other at their free extremities. The
+only existing animals in which an approximation
+is found to the prepubic bones in Pterodactyles
+are Crocodiles, in bones which most writers term the
+pubic bones. This resemblance, without showing
+any strong affinity with the Crocodilia, indicates
+that Crocodiles have more in common with the
+fossil flying animals than any other group of existing
+reptiles; for other reptiles all want prepubic bones,
+or bones in front of the pubic region.</p>
+
+
+<h4>THE HIND LIMB</h4>
+
+<p>The hind limb is exceptionally long in proportion
+to the back. This is conspicuous in the skeletons of
+the short-tailed Pterodactyles, and is also seen in
+Dimorphodon. In Rhamphorhynchus the hind limb
+is relatively much shorter, so that the animal, when
+on all fours, may have had an appearance not unlike
+a Bat in similar position. The limb is exceptionally
+short in the little <i>Ptenodracon brevirostris</i>. The
+bones of the hind limb are exceptionally interesting.
+One remarkable feature common to all the specimens
+is the great elongation of the shin bones relatively to
+the thigh bones. The femur is sometimes little more
+than half the length of the tibia, and always shorter
+than that bone. The proportions are those of
+mammals and birds. Some mammals have the leg
+shorter than the thigh, but mammals and birds
+alone, among existing animals, have the proportions
+<span class='pagenum'><a name="Page_100" id="Page_100">[Pg 100]</a></span>
+which characterise Pterodactyles. The foot appears
+to have been applied to the ground not always as in
+a bird, but more often in the manner of reptiles, or
+mammals in which the digits terminate in claws.</p>
+
+
+<h4>THE FEMUR</h4>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_33" id="Fig_33"></a>
+<span class="caption">FIG. 33. &nbsp;  THE FEMUR</span>
+<img src="images/i_117.jpg" width="640" height="345" alt="FIG. 33." title="FIG. 33." />
+<p class="center">On the right is a front view of femur of a bear. In the middle are front and
+side views of the femur of Ornithocheirus. On the left is the femur
+of Echidna. These comparisons illustrate the mammalian
+characters of the Pterodactyle thigh bone</p>
+</div>
+
+
+<p>The thigh bone, on account of the small size of
+many of the specimens, is not always quite clear
+evidence as an indication of technical resemblance to
+other animals. The bone is always a little curved,
+has always a rounded, articular head, and rounded
+distal condyles. Its most remarkable features are
+shown in the large, well-preserved specimens from
+the Cambridge Greensand. The rounded, articular
+head is associated with a constricted neck to the
+bone, followed by a comparatively straight shaft with
+distal condyles, less thickened than in mammals. No
+bird is known, much less any reptile, with a femur
+like Ornithocheirus. Only among Mammals is a
+similar bone known with a distinct neck; and only
+a few mammals have the exceptional characters of
+<span class='pagenum'><a name="Page_101" id="Page_101">[Pg 101]</a></span>
+the rounded head and constricted neck at all
+similar to the Cretaceous Pterodactyles. A few
+types, such as the higher apes, the Hyrax, and
+animals especially active in the hind limb, have a
+femur at all resembling the Pterodactyle in the pit
+for the obturator externus muscle, behind the trochanter
+major, such as is seen in a small femur from
+Ashwell. The femur varies in different genera, so as
+to suggest a number of mammalia rather than any
+particular animal for comparison. These approximations
+may be consequences of the ways in which
+the bones are used. When functional modifications
+of the skeleton are developed, so as to produce
+similar forms of bones, the muscles to which they
+give attachment, which act upon the bones, and
+determine their growth, are substantially the same.
+In the <i>Pterodactylus longirostris</i> the femur corresponds
+in length to about eleven dorsal vertebr&aelig;.
+The end next the shin bone is less expanded than
+is usual among Mammals, and rather suggests an
+approach to the condition in Crocodiles, in the moderate
+thickness and breadth of the articular end, and
+the slight development of the terminal pulley-joint.
+One striking feature of the femur is the circumstance
+that the articular head, as compared with the distal
+end, is directed forward and very slightly inward and
+upward. So that allowing for the outward divergence
+of the pelvic bones, as they extend forward, there
+must have been a tendency to a knock-kneed approximation
+of the lower ends of the thigh bones,
+as in Mammals and Birds, rather than the outward
+divergence seen in Reptiles.</p>
+
+<p>Apparently the swing of the leg and foot, as it
+hung on the distal end of the femur, must have
+<span class='pagenum'><a name="Page_102" id="Page_102">[Pg 102]</a></span>
+tended rather to an inward than to an outward
+direction, so that the feet might be put down upon
+the same straight line; this arrangement suggests
+rapid movement.</p>
+
+
+<h4>TIBIA AND FIBULA</h4>
+
+<div class="figcenter" style="width: 512px;">
+<a name="Fig_34" id="Fig_34"></a>
+<span class="caption">FIG. 34. &nbsp;  COMPARISON OF THE TIBIA AND FIBULA
+IN ORNITHOSAUR AND VULTURE</span>
+<img src="images/i_119.jpg" width="512" height="480" alt="FIG. 34." title="FIG. 34." />
+</div>
+
+
+<p>In <i>Pterodactylus longirostris</i> the tibia is slender,
+more than a fifth longer than the femur. A crest is
+never developed at the proximal end, like that seen
+in the Guillemot and Diver and other water birds.
+The bone is of comparatively uniform thickness down
+the shaft in most of the Solenhofen specimens, as in
+most birds. At the distal end the shin bone commonly
+has a rounded, articular termination, like that
+seen in birds. This is conspicuous in the <i>Pterodactylus
+grandis</i>. In other specimens the tarsal bones,
+which form this pulley, remain distinct from the tibia;
+and the upper row of these bones appears to consist
+<span class='pagenum'><a name="Page_103" id="Page_103">[Pg 103]</a></span>
+of two bones, like those which in many Dinosaurs
+combine to form the pulley-like end of the tibia
+which represents the bird's drum-stick bone. They
+correspond with the ankle bones in man named
+astragalus and os calcis.</p>
+
+<p>Complete English specimens of tibia and fibula are
+found in the genus Dimorphodon from the Lias, in
+which the terminal pulley of the distal end has some
+expansion, and is placed forward towards the front of
+the tibia, as in some birds. The rounded surface of
+the pulley is rather better marked than in birds.
+The proximal end of the shaft is relatively stout, and
+is modified by the well-developed fibula, which is a
+short external splint bone limited to the upper half
+of the tibia, as in birds; but contributing with it to
+form the articular surface for the support of the
+lower end of the femur, taking a larger share in that
+work than in birds. Frequently there is no trace of
+the fibula visible in Solenhofen specimens as preserved;
+or it is extremely slender and bird-like, as in
+<i>Pterodactylus longirostris</i>. In Rhamphorhynchus it
+appears to extend the entire length of the tibia, as in
+Dinosaurs. In the specimens from the Cambridge
+Greensand there is indication of a small proximal crest
+to the tibia with a slight ridge, but no evidence that
+this is due to a separate ossification. The patella, or
+knee-cap, is not recognised in any fossil of the group.
+There is no indication of a fibula in the specimens
+thus far known from the Chalk rocks either of Kansas
+in America, or in England.</p>
+
+<p>The region of the tarsus varies from the circumstance
+that in many specimens the tibia terminates
+downward in a rounded pulley, like the drum-stick of
+a bird; while in other specimens this union of the
+<span class='pagenum'><a name="Page_104" id="Page_104">[Pg 104]</a></span>
+proximal row of the tarsal bones with the tibia does
+not take place, and then there are two rows of
+separate tarsal bones, usually with two bones in each
+row. When the upper row is united with the tibia
+the lower row remains distinct from the metatarsus,
+though no one has examined these separate tarsal
+bones so as to define them.</p>
+
+
+<h4>THE FOOT</h4>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_35" id="Fig_35"></a>
+<span class="caption">FIG. 35. &nbsp;  METATARSUS AND DIGITS IN THREE TYPES
+OF ORNITHOSAURS</span>
+<img src="images/i_121.jpg" width="640" height="393" alt="FIG. 35." title="FIG. 35." />
+</div>
+
+<p>The foot sometimes has four toes, and sometimes
+five. There are four somewhat elongated, slender
+metatarsal bones, which are separate from each other
+and never blended together, as in birds. There has
+been a suspicion that the metatarsal bones were
+separate in the young Arch&aelig;opteryx. In the young
+of many birds the row of tarsal bones at the proximal
+end of the metatarsus comes away, and there is a
+partial division between the metatarsal bones, though
+they remain united in the middle. And among Penguins,
+in which the foot bones are applied to the
+ground instead of being carried in the erect position
+of ordinary birds, there is always a partial separation
+<span class='pagenum'><a name="Page_105" id="Page_105">[Pg 105]</a></span>
+between the metatarsal bones, though they become
+blended together. The Pterodactyle is therefore
+different from birds in preserving the bones distinct
+through life, and this character is more like Reptiles
+than Mammals. The individual bones are not
+like those of Dinosaurs, and diverge in Rhamphorhynchus
+as though the animals were web-footed.
+There is commonly a rudimentary fifth metatarsal.
+It is sometimes only a claw-shaped appendage, like
+that seen in the Crocodile. It is sometimes a short
+bone, completely formed, and carrying two phalanges
+in Solenhofen specimens: though no trace of these
+phalanges is seen in the large toothless Pterodactyles
+from the Cretaceous rocks of North America. In the
+<i>Pterodactylus longirostris</i> the number of foot bones
+on the ordinary digits is two, three, four, five, as in
+lizards; but the short fifth metatarsal has only two
+toe bones. In Dimorphodon the fifth digit was bent
+upward, and supported a membrane for flight. There
+are slight variations in the number of foot bones.
+In the species <i>Pterodactylus scolopaciceps</i> the number
+of bones in the toes follows the formula two, three,
+three, four. In <i>Pterodactylus micronyx</i> the number is
+two, three, three, three. The terminal claws are much
+less developed than is usual with Birds; and there is
+a difference from Bats in the unequal length of the
+digits. Taken as a whole, the foot is perhaps more
+reptilian than avian, and in some genera is crocodilian.</p>
+
+<p>The foot is the light foot of an active animal. Von
+Meyer thought that the hind legs were too slender
+to enable the animal to walk on land; and Professor
+Williston, of the University of Kansas, remarks that
+the rudimentary claws and weak toes indicate that
+<span class='pagenum'><a name="Page_106" id="Page_106">[Pg 106]</a></span>
+the animal could not have used the feet effectively
+for grasping, while the exceedingly free movement
+of the femur indicates great freedom of movement of
+the hind legs; and he concludes that the function
+of the legs was chiefly for guidance in flight through
+their control over the movements, and expresses his
+belief that the animal could not have stood upon the
+ground with its feet. There may be evidence to
+sustain other views. If the limb bones are reconstructed,
+they form limbs not wanting in elegance
+or length. If it is true, as Professor Williston suggests,
+that the weight of his largest animals with the
+head three feet long, and a stretch of wing of eighteen
+or nineteen feet, did not exceed twenty pounds, there
+can be no objection to regarding these animals as
+quadrupeds, or even as bipeds, on the ground of the
+limbs lacking the strength necessary to support the
+body. The slender toes of many birds, and even the
+two toes of the ostrich, may be thought to give less
+adequate support for those animals than the metatarsals
+and digits of Pterodactyles.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_107" id="Page_107">[Pg 107]</a></span></p>
+<h2><a name="CHAPTER_XI" id="CHAPTER_XI"></a><small>CHAPTER XI</small><br /><br />
+
+SHOULDER-GIRDLE AND
+FORE LIMB</h2>
+
+
+<h4>STERNUM</h4>
+
+<p>The sternum is always a distinguishing part of
+the bony structure of the breast. In Crocodiles
+it is a cartilage to which the sternal ribs unite; and
+upon its front portion a flat knife-like bone called
+the interclavicle is placed. In lizards like the Chameleon,
+it is a lozenge-shaped structure of thin bony
+texture, also bearing a long interclavicle, which supports
+the clavicular bones, named collar bones in
+man, which extend outward to the shoulder blades.
+Among mammals the sternum is usually narrow and
+flat, and often consists of many successive pieces in
+the middle line, on the under side of the body.
+Among Bats the anterior part is somewhat widened
+from side to side, to give attachment to the collar
+bones, but the sternum still remains a narrow bone,
+much narrower than in Dolphins, and not differing
+in character from many other Mammals, notwithstanding
+the Bat's power of flight. The bone develops
+a median keel for the attachment of the
+muscles of the breast, but something similar is seen
+in burrowing Insectivorous mammals like the Moles.
+<span class='pagenum'><a name="Page_108" id="Page_108">[Pg 108]</a></span>
+So that, as Von Meyer remarked, the presence of a
+keel on the sternum is not in itself sufficient evidence
+to prove flight.</p>
+
+<p>Among birds the sternum is greatly developed.
+Broad and short in the Ostrich tribe, it is devoid of
+a keel; and therefore the keel, if present in a bird,
+is suggestive of flight. The keel is differently developed
+according to the mode of attachment of the
+several pectoral muscles which cover a bird's breast.
+In several water birds the keel is strongly developed
+in front, and dies away towards the hinder part of
+the sternum, as in the Cormorant and its allies. The
+sternum in German Pterodactyles is most nearly
+comparable to these birds.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_36" id="Fig_36"></a>
+<span class="caption">FIG. 36. &nbsp; COMPARISON OF THE STERNUM</span>
+<img src="images/i_125.jpg" width="640" height="376" alt="FIG. 36." title="FIG. 36." />
+</div>
+
+<p>In the Solenhofen Slate the sternum is fairly well
+preserved in many Ornithosaurs. It is relatively
+shorter than in birds, and is broader than long; but
+not very like the sternum of reptile or mammal in
+form. The keel is limited to the anterior part of the
+shield of the sternum, as in Merganser and the Cormorant,
+and is prolonged forward for some distance in
+advance of it. Von Meyer noticed the resemblance of
+this anterior process to the interclavicle of the Croco<span class='pagenum'><a name="Page_109" id="Page_109">[Pg 109]</a></span>dile
+in position; but it is more like the keel of a bird's
+sternum, and is not a separate bone as in Reptiles.
+In Pterodactyles from the Cretaceous rocks, the side
+bones, called coracoids, are articulated to saddle-shaped
+surfaces at the hinder part of the base of
+this keel, which are parallel in Ornithocheirus, as in
+most birds, but overlap in Ornithodesmus, as in
+Herons and wading birds.</p>
+
+<div class="figcenter" style="width: 484px;">
+<a name="Fig_37" id="Fig_37"></a>
+<span class="caption">FIG. 37. &nbsp;  STERNUM IN ORNITHOCHEIRUS FROM THE
+CAMBRIDGE GREENSAND</span>
+<img src="images/i_126.jpg" width="484" height="480" alt="FIG. 37." title="FIG. 37." />
+<p class="center">Showing the strong keel and the facets for the coracoid bones on its hinder
+border above the lateral constrictions</p>
+</div>
+
+<p>The keel was pneumatic, and when broken is seen
+to be hollow, and appears to have been exceptionally
+high in Rhamphorhynchus, a genus in which the
+wing bones are greatly elongated. Von Meyer found
+<span class='pagenum'><a name="Page_110" id="Page_110">[Pg 110]</a></span>
+in Rhamphorhynchus on each side of the sternum a
+separate lateral plate with six pairs of sternal ribs,
+which unite the sternum with the dorsal ribs, as in
+the young of some birds. The hinder surface of the
+sternum is imperfectly preserved in the toothless
+Pterodactyles of Kansas. Professor Williston states
+that the bone is extremely thin and pentagonal in
+outline, projecting in front of the coracoids, in a
+stout, blunt, keel-like process, similar to that seen in
+the Pterodactyles of the Cambridge Greensand.
+American specimens have not the same notch behind
+the articulation for the coracoid to separate it
+from the transverse lateral expansion of the sternal
+shield. The lateral margin in the Cambridge Greensand
+specimens figured by Professor Owen and myself
+is broken; but Professor Williston had the good
+fortune to find on the margin of the sternum the
+articular surfaces which gave attachment to the sternal
+ribs. The margin of the sternal bone thickens at these
+facets, four of which are preserved. The sternum in
+Ornithostoma was about four and a half inches long
+by less than five and a half inches wide. The median
+keel extends forward for rather less than two inches,
+while in the smaller Cambridge species of Ornithocheirus
+it extends forward for less than an inch and
+a half.</p>
+
+<p>A sternum of this kind is unlike that of any other
+animal, but has most in common with a bird; and
+may be regarded as indicating considerable power
+of flight. The bone cannot be entirely attributed to
+the effect of flight, since there is no such expanded
+sternal shield in Bats. The small number of sternal
+ribs is even more characteristic of birds than mammals
+or reptiles.</p>
+<p><span class='pagenum'><a name="Page_111" id="Page_111">[Pg 111]</a></span></p>
+
+<h4>THE SHOULDER-GIRDLE</h4>
+
+<p>The bones which support the fore limb are one
+of the distinctive regions of the skeleton defining
+the animal's place in nature. Among most of the
+lower vertebrata, such as Amphibians and Reptiles,
+the girdle is a double arch&mdash;the arch of the
+collar bone or clavicles in front, and the arch of the
+shoulder-blade or scapula behind. The clavicular
+arch, when it exists, is formed of three or five parts&mdash;a
+medium bar named the interclavicle, external to
+which is a pair of bones called clavicles, reaching to
+the front of the scapul&aelig; when they are present; and
+occasionally there is a second pair of bones called
+supraclavicles, extending from the clavicles up the
+front margins of the scapul&aelig;. Thus the clavicular
+arch is placed in front of the scapular arch. The
+supraclavicles are absent from all living Reptiles, and
+the clavicles are absent from Crocodiles. The interclavicle
+is absent from all mammals except Echidna
+and Ornithorhynchus. Clavicles also may be absent
+in some orders of mammals. Hence the clavicular
+arch may be lost, though the collar bones are retained
+in man.</p>
+
+<p>The scapular arch also is more complicated and
+more important in the lower than in the higher
+vertebrata. It may include three bones on each side
+named coracoid, precoracoid, and scapula. But in
+most vertebrates the coracoid and precoracoid appear
+never to have been segmented so as to be separated
+from each other; and it is only among extinct types
+of reptiles, which appear to approximate to the Monotreme
+mammals, that separate precoracoid bones are
+found; though among most mammals, probably,
+<span class='pagenum'><a name="Page_112" id="Page_112">[Pg 112]</a></span>
+there are stages of early development in which precoracoids
+are represented by small cartilages, though
+few mammals except Edentata like the Sloths and
+Ant-eaters, retain even the coracoids as distinct bones.
+Therefore, excepting the Edentata and the Monotremes,
+the distinctive feature of the mammalian
+shoulder-girdle appears to be that the limbs are supported
+by the shoulder-blades, termed the scapul&aelig;.</p>
+
+<p>Among reptiles there are several distinct types
+of shoulder-girdle. Chelonians possess a pair of
+bones termed coracoids which have no connexion
+with a sternum; and their scapul&aelig; are formed of two
+widely divergent bars, divided by a deeper notch than
+is found in any fossil reptiles. Among Lizards both
+scapula and coracoid are widely expanded, and the
+coracoid is always attached to the sternum. Chameleons
+have the blade of the scapula long and slender,
+but the coracoid is always as broad as it is long.
+Crocodiles have the bone more elongated, so that it
+has somewhat the aspect of a very strong first sternal
+rib when seen on the ventral face of the animal. The
+bone is perforated by a foramen, which would probably
+lie in the line of separation from the precoracoid
+if any such separation had ever taken place. The
+scapula, or shoulder-blade, of Crocodiles is a similar
+flat bone, very much shorter than the scapula of a
+Chameleon, and more like that of the New Zealand
+Hatteria. Thus there is very little in common between
+the several reptilian types of shoulder-girdle.</p>
+
+<p>In birds the apparatus for the support of the wings
+has a far-off resemblance to the Crocodilian type.
+The coracoid bones, instead of being directed laterally
+outward and upward from the sternum, as among
+Crocodiles, are directed forward, so as to prolong the
+<span class='pagenum'><a name="Page_113" id="Page_113">[Pg 113]</a></span>
+line of the breast bone, named the sternum. The
+bird's coracoid is sometimes flattened towards the
+breast bone among Swans and other birds; yet as a
+rule the coracoid is a slender bar, which combines
+with the still more slender and delicate blade of the
+scapula, which rests on the ribs, to make the articulation
+for the upper arm bone. Among reptiles the
+scapula and coracoid are more or less in the same
+straight line, as in the Ostrich, but in birds of flight
+they meet at an angle which is less than a right angle,
+and where they come in contact the external surface
+is thickened and excavated to make the articulation
+for the head of the humerus. There is nothing like
+this shoulder-girdle outside the class of birds, until it
+is compared with the corresponding structure in these
+<span class='pagenum'><a name="Page_114" id="Page_114">[Pg 114]</a></span>
+extinct animals called Pterodactyles. The resemblance
+between the two is surprising. It is not
+merely the identity of form in the coracoid bone and
+the scapula, but the similar angle at which they meet
+and the similar position of the articulation for the
+humerus. Everything in the Pterodactyle's shoulder-girdle
+is bird-like, except the absence of the representative
+of the clavicles, that forked <b>V</b>-shaped bone
+of the bird which in scientific language is known as
+the furculum, and is popularly termed the "merry-thought."
+This kind of shoulder-girdle is found in
+the genera from the Lias and the Oolitic rocks, both
+of this country and Germany.</p>
+
+
+<div class="figcenter" style="width: 553px;">
+<a name="Fig_38" id="Fig_38"></a>
+<span class="caption">FIG. 38. &nbsp; COMPARISON OF SCAPULA AND CORACOID IN
+THREE PTERODACTYLES AND A BIRD</span>
+<img src="images/i_130.jpg" width="553" height="480" alt="FIG. 38." title="FIG. 38." />
+</div>
+
+
+
+
+<p>In the Cretaceous rocks the scapula presents, in
+most cases, a different appearance. The coracoid is
+an elongated, somewhat triangular bone, compressed
+on the outer margin as in birds, but differing alike
+from birds and other Pterodactyles in not being
+prolonged forward beyond the articulation for the
+humerus. In these Cretaceous genera, toothed and
+toothless alike, the articulation for the upper arm
+bone truncates the extremity of the coracoid, so that
+the bone is less like that of a bird in this feature.
+Perhaps it shows a modification towards the crocodilian
+direction. The scapula, which unites with the
+coracoid at about a right angle, is similarly truncated
+by the articular surface for the humerus; but the
+bone is somewhat expanded immediately beyond the
+articulation, and compressed; and instead of being
+directed backward, it is directed inward over the ribs
+to articulate with the neural arches of the early
+dorsal vertebr&aelig; in the genera found in strata associated
+with the Chalk. As the bone approaches
+this articulation, it thickens and widens a little,
+<span class='pagenum'><a name="Page_115" id="Page_115">[Pg 115]</a></span>
+becoming suddenly truncated by an ovate facet,
+which exactly corresponds to the transversely ovate
+impression, concave from front to back, which is seen
+in the neural arches of the dorsal vertebr&aelig; on which
+it fits. This condition is not present in all Cretaceous
+Pterodactyles. It does not occur in the Kansas fossil,
+named by Professor Marsh, Nyctodactylus. And it
+<span class='pagenum'><a name="Page_116" id="Page_116">[Pg 116]</a></span>
+appears to be absent from the Pterodactyles of the
+English Weald, named Ornithodesmus.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_39" id="Fig_39"></a>
+<span class="caption">FIG. 39. &nbsp; THE NOTARIUM</span>
+<img src="images/i_132a.jpg" width="640" height="252" alt="FIG. 39. THE NOTARIUM" title="FIG. 39." />
+<p class="center">An ossification which gives attachment to the scapul&aelig; seen in
+the early dorsal vertebra of Ornithocheirus<br />
+(From the Cambridge Greensand)</p>
+</div>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_40" id="Fig_40"></a>
+<span class="caption">FIG. 40. &nbsp;  RESTORATION OF THE SHOULDER-GIRDLE IN THE
+CRETACEOUS ORNITHOCHEIRUS</span>
+<img src="images/i_132b.jpg" width="640" height="466" alt="FIG. 40." title="FIG. 40." />
+<p class="center">Showing how the scapul&aelig; articulate with a vertebra and the articulation
+of the coracoids with the sternum. The humeral articulation with
+the coracoid is unlike the condition shown in other Ornithosaurs</p>
+</div>
+
+
+<p>There is no approach to this transverse position of
+the scapul&aelig; among birds. And while the form of
+the bones in the older genera of Ornithosaurs is
+singularly bird-like, the angular arrangement in this
+Cretaceous genus is obtained by closely approximating
+the articulations on the sternum, so that the
+coracoids extend outward as in reptiles, instead of
+forward as in birds; and the extremities of the
+scapul&aelig; similarly approximate towards each other.
+This rather recalls the relative positions of scapula
+and coracoid among crocodiles. If crocodile and
+bird had been primitive types of animals instead of
+surviving types, it might almost seem as though
+there had been a cunning and harmonious blending
+of one with the other in evolving this form of
+shoulder-girdle.</p>
+
+
+<h4>THE FORE LIMB</h4>
+
+<p>The bones of the fore limb, generally, correspond
+in length with the similar parts of the hind limb.
+The upper arm bone corresponds with the upper leg
+bone, and the fore-arm bone is as long as the fore-leg
+bone; then differences begin. The bones which
+correspond to the back of the hand in man, termed
+the metacarpus, are variable in length in Pterodactyles&mdash;sometimes
+very long and sometimes short. The
+wing metacarpal bone is always stout, and the others
+are slender. The extremity of the metacarpus was
+applied to the ground. Three small digits of the
+hand are developed from the three small metacarpal
+bones, and terminate in large claws.</p>
+
+<p>The great wing finger was bent backward, and only
+<span class='pagenum'><a name="Page_117" id="Page_117">[Pg 117]</a></span>
+touched the ground where it fitted upon the wing
+metacarpal bone. It appears sometimes to have
+been as long as the entire vertebral column.</p>
+
+<p>Owing to the circumstance that the joint in the
+arm in Pterodactyles was not at the wrist as among
+birds, but between the metacarpus and the phalanges,
+it follows that the fore limb was longer than the hind
+limb when the metacarpus was long; but the difference
+would not interfere with the movements of the
+animal, either upon four feet or on two feet, for in bats
+and birds the disproportion in length is greater.</p>
+
+
+<h4>HUMERUS OR UPPER ARM BONE</h4>
+
+<p>The first bone in the fore-arm, the humerus, is
+remarkable chiefly for the compressed crescent form
+of its upper articular end, which is never rounded
+like the head of the upper arm bone in man, and
+secondly for the great development of the external
+process of bone near that end, termed the radial
+crest. Sir Richard Owen compared the bone to the
+humerus of both birds and crocodiles, but in its upper
+articular end the crocodile bone may be said to be
+more like a bird than it is like the Pterodactyle. In
+flying reptiles the articular surface next to the shoulder-girdle
+is somewhat saddle-shaped, being concave from
+side to side above and convex vertically, while most
+animals with which it can be compared have the
+articular head of the bone convex in both directions.
+A remarkable exception to this general rule is found
+in some fossil animals from South Africa, which, from
+resemblance to mammals in their teeth, have been
+termed Theriodonts. They sometimes have the head
+of the bone concave from side to side and convex in
+the vertical direction. To this condition Ornithorhynchus
+<span class='pagenum'><a name="Page_118" id="Page_118">[Pg 118]</a></span>
+makes a slight approximation. The singular
+expansion of the structure called the radial crest
+finds no close parallel in reptiles, though Crocodiles
+have a moderate crest on the humerus in the same
+position; and in Theriodonts the radial crest extends
+much further down the shaft of the humerus. No
+bird has a radial crest of a similar kind, though it
+is prolonged some way down the shaft in Arch&aelig;opteryx.
+In Pterodactyles it sometimes terminates
+outward in a smooth, rounded surface, which might
+have been articular if any structure could have articulated
+with it. There is also a moderate expansion of
+the bone on the ulnar side in some Pterodactyles, so
+that the proximal end often incloses nearly three-fourths
+of an ovate outline. The termination of the
+radial crest is at the opposite end of this oval to the
+wider articular part of the head of the bone, in
+some specimens from the Cambridge Greensand. The
+radial crest is more extended in Rhamphorhynchus.
+All specimens of the humerus show a twist in the
+length of the bone, so that the end towards the fore-arm,
+which is wider than the shaft, makes a right
+angle with the radial crest on the proximal end,
+which is not seen in birds. The shaft of the humerus
+is always stouter than that of the femur, though
+different genera differ in this respect.</p>
+
+<p>The humerus in genera from rocks associated with
+the Chalk presents two modifications, chiefly seen in
+the characters of the distal end of the bone. One of
+these is a stout bone with a curiously truncated end
+where it joins the two bones of the fore-arm; and
+the other is more or less remarkable for the rounded
+form of the distal condyles. Both types show distinct
+articular surfaces. The inner one is somewhat oblique
+<span class='pagenum'><a name="Page_119" id="Page_119">[Pg 119]</a></span>
+and concave, the outer one rounded; the two being
+separated by a concave channel, so that the ulna
+makes an oblique articulation with the bone as in
+birds, and the radius articulates by a more or less
+truncated or concave surface.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_41" id="Fig_41"></a>
+<span class="caption">FIG. 41. &nbsp;  COMPARISON OF THE HUMERUS IN
+PTERODACTYLE AND BIRD</span>
+<img src="images/i_136.jpg" width="640" height="434" alt="FIG. 41." title="FIG. 41." />
+</div>
+
+
+
+
+<h4>ULNA AND RADIUS</h4>
+
+<p>The bones of the fore-arm are similar to each other
+in size, and if there be any difference between them
+the ulna is slightly the larger. There is some evidence
+that in Rhamphorhynchus the upper end of the ulna
+was placed behind the radius, probably in consequence
+of the mode of attachment of those bones to the
+humerus. The ulna abutted towards the inner and
+lower border, while the radius was towards the upper
+border, consequent upon the twist in the humerus.
+This condition corresponds substantially with the
+arrangement in birds, but differs from birds in the
+relatively more important part taken by the radius
+in making the articulation. The bones are compared
+in Dimorphodon with the Golden Eagle drawn of the
+same size (<a href="#Fig_42">Fig. 42</a>). In birds the ulna supports the great
+feathers of the wing, and this may account for the
+<span class='pagenum'><a name="Page_120" id="Page_120">[Pg 120]</a></span>
+size of the bone. The ulna is best seen at its proximal
+end in the specimens from the Cambridge
+Greensand, where there is a terminal olecranon ossification
+forming an oblique articulation, which frequently
+comes away and is lost. It is sometimes
+well preserved, and indicated by a suture. The
+examples of ulna from the Lias show a slight expansion
+of the bone at both ends, and at the distal
+end toward the wrist the articulation is well defined,
+where the bone joins the carpus. The larger specimens
+of the bone are broken. The distal articular
+surface is only connected with the proximal end of
+the bone in small specimens: it always shows on
+the one margin a concavity, followed by a prominent
+boss, and an oblique articulation beyond the boss.
+On the side towards the radius, on the lower end of
+the shaft there is an angular ridge, which marks the
+<span class='pagenum'><a name="Page_121" id="Page_121">[Pg 121]</a></span>
+line along which the ulna overlaps the radius. The
+lower end of the radius has a simple, slightly convex
+articulation, somewhat bean-shaped. No rotation
+of these bones on each other was possible as in
+man. There is a third bone in the fore-arm. This
+bone, named the pteroid, is commonly seen in skeletons
+from Solenhofen. It was regarded by Von
+Meyer as having supported the wing membrane in
+flight. Some writers have interpreted it as an essential
+part of the Pterodactyle skeleton, and Von
+Meyer thought that it might possibly indicate a fifth
+digit in the hand. The only existing structure at all
+like it is seen in the South African insectivorous
+mammal named <i>Chrysochloris capensis</i>, the golden
+mole, which also has three bones in the fore-arm,
+the third bone extending half-way up towards the
+humerus. In that animal the third bone appears to
+be behind the others and adjacent to the ulna. In
+the German fossils the pteroid articulated with a
+separate carpal or metacarpal bone, placed on the side
+of the arm adjacent to the radius, and the radius
+is always more inward than the ulna. If the view
+suggested by Von Meyer is adopted, this bone would
+be a first digit extending outward and backward
+towards the humerus. That view was adopted by
+Professor Marsh. It involves the interpretation of
+what has been termed the lateral carpal as the first
+metacarpal bone, which would be as short as that
+of a bird, but turned in the opposite direction backward.
+The first digit would then only carry one
+phalange, and would not terminate in a claw, but lie
+in the line of the tendon which supports the anterior
+wing membrane of a bird.</p>
+
+<div class="figcenter" style="width: 552px;">
+<a name="Fig_42" id="Fig_42"></a>
+<span class="caption">FIG. 42. &nbsp;  COMPARISON OF THE BONES OF THE FORE-ARM
+IN BIRD AND ORNITHOSAUR</span>
+<img src="images/i_137.jpg" width="552" height="480" alt="FIG. 42." title="FIG. 42." />
+</div>
+
+
+<p>The third bone in the fore-arm of Chrysochloris
+<span class='pagenum'><a name="Page_122" id="Page_122">[Pg 122]</a></span>
+does not appear to correspond to a digit. The bone
+is on the opposite side of the arm to the similar
+bone of a Pterodactyle, and therefore cannot be the
+same structure in the Golden Mole. The interpretation
+which makes the pteroid bone the first digit
+has the merit of accounting for the fifth digit of the
+hand. All the structures of the hand are consistent
+with this view. The circumstance that the bone is
+rarely found in contact with the radius, but diverging
+from it, shows that it plays the same part in stretching
+the membrane in advance of the arm, that the fifth
+digit holds in supporting the larger wing membrane
+behind the arm.</p>
+
+<p>According to Professor Williston, the American
+toothless Pterodactyle Ornithostoma has but a single
+phalange on the corresponding first toe of the hind
+foot, and that bone he describes as long, cylindrical,
+gently curved, and bluntly pointed. There is some
+support for this interpretation; but I have not seen
+any English or German Pterodactyles with only one
+phalange in the first toe.</p>
+
+<p>The wing in Pterodactyles would thus be stretched
+between two fingers which are bent backward, the
+three intermediate digits terminating in claws.</p>
+
+
+<h4>THE CARPUS</h4>
+
+<p>The wrist bones in the reptilia usually consist of
+two rows. In Crocodiles, in the upper row there is
+a large inner and a small outer bone, behind which
+is a lunate bone, the remainder of the carpus being
+cartilaginous. Only one carpal is converted into
+bone in the lower row. It is placed immediately
+under the smaller upper carpal. In Chelonians, the
+turtle and tortoise group, the characters of the carpus
+<span class='pagenum'><a name="Page_123" id="Page_123">[Pg 123]</a></span>
+vary with the family. In the upper row there are
+usually two short carpals, which may be blended,
+under the ulna; while the two under the radius are
+commonly united. The lower row is made up of
+several small bones. Lizards, too, usually have three
+bones in the proximal row and five smaller bones
+in the distal row.</p>
+
+<p>The correspondence of the distal carpals with
+the several metacarpal bones of the middle hand
+is a well-known feature of the structure of the
+wrist.</p>
+
+<p>Von Meyer remarks that the carpus is made up of
+two rows of small bones in the Solenhofen Pterodactyles;
+while in birds there is one row consisting
+of two bones. The structure of the carpus is not
+distinct in all German specimens; but in the short-tailed
+Solenhofen genera the bones in the two rows
+retain their individuality.</p>
+
+<p>In all the Cretaceous genera the carpal bones of
+each row are blended into a single bone, so that two
+bones are superimposed, which may be termed the
+proximal and distal carpals. One specimen shows
+by an indication of sutures the original division of
+the distal carpal into three bones; and the separated
+constituent bones are very rarely met with. Two
+bones of the three confluent elements contribute to the
+support of the wing metacarpal, and the third gives
+an articular attachment to the bone which extends
+laterally at the inner side of the carpus, which I
+now think may be the first metacarpal bone turned
+backward towards the humerus. The three component
+bones meet in the circular pneumatic foramen
+in the middle of the under side of the distal
+carpal. There is no indication of division of the
+<span class='pagenum'><a name="Page_124" id="Page_124">[Pg 124]</a></span>
+proximal carpal in these genera into constituent
+bones.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_43" id="Fig_43"></a>
+<span class="caption">FIG. 43. &nbsp;  CARPUS FROM ORNITHOCHEIRUS</span>
+<p class="center">(Cambridge Greensand)</p>
+<img src="images/i_141.jpg" width="640" height="254" alt="FIG. 43." title="FIG. 43." />
+</div>
+
+
+
+<p>This condition is somewhat different from birds.
+In 1873 Dr. Rosenberg, of Dorpat, showed that
+there is in the bird a proximal carpal formed of two
+elements, and a distal carpal also formed of two
+elements. Therefore the two constituents of the
+distal carpal in the bird which blends in the mature
+animal with the metacarpus, forming the rounded
+pulley joint, may correspond with two of the three
+bones in the Cretaceous Pterodactyle <i>Ornithocheirus.</i></p>
+
+<p>The width of a proximal carpal rarely exceeds two
+inches, and that of a distal carpal is about an inch
+and three-quarters. Two such bones when in contact
+would not measure more than one inch in depth.
+The lower surface shows that the wing had some
+rotary movement upon the carpus outward and
+backward.</p>
+
+
+<h4>METACARPUS</h4>
+
+<p>The metacarpus consists of bones which correspond
+to the back of the hand. The first digit of
+the hand in clawed animals has the metacarpal bone
+short, or shorter than the others. Among mammals
+metacarpal bones are sometimes greatly elongated;
+and a similar condition is found in Pterodactyles, in
+which the metacarpal bone may be much longer
+<span class='pagenum'><a name="Page_125" id="Page_125">[Pg 125]</a></span>
+than the phalange which is attached to it. Two
+metacarpal bones appear to be singularly stouter
+than the others. The first bone of the first digit, if
+rightly determined, is much shorter than the others,
+and is, in fact, no longer than the carpus (<a href="#Fig_43">Fig. 43</a>). It
+is a flat oblong bone, attached to the inner side of
+the lower carpal, and instead of being prolonged
+distally in the same direction as the other metacarpal
+bones, is turned round and directed upward,
+so that its upper edge is flush with the base of the
+radius, and gives attachment to a bone which resembles
+a terminal phalange of the wing finger.
+According to this interpretation it is the first and
+only phalange in the first digit. The bone is often
+about half as long as the fore-arm, terminates upward
+in a point, is sometimes curved, and frequently
+diverges outward from the bones of the fore-arm,
+as preserved in the associated skeleton, being
+stretched towards the radial crest of the humerus.
+This mode of attachment of the supposed first metacarpal,
+which is true for all Cretaceous pterodactyles,
+has not been shown to be the same for all those
+from the Solenhofen Slate. There is no greater
+anomaly in this metacarpal and phalange on the
+<span class='pagenum'><a name="Page_126" id="Page_126">[Pg 126]</a></span>
+inner side being bent backward, than there is in the
+wing finger being bent backward on the outer side.
+The three slender intervening digits extend forward
+between them, as though they were applied to the
+ground for walking.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_44" id="Fig_44"></a>
+<span class="caption">FIG. 44. &nbsp;  METACARPUS IN TWO ORNITHOSAURS</span>
+<img src="images/i_142.jpg" width="640" height="336" alt="FIG. 44." title="FIG. 44." />
+</div>
+
+
+<p>The bone which is usually known as the wing
+metacarpal is frequently stouter at the proximal end
+towards the carpus than towards the phalange. At
+the carpal end it is oblong and truncated, with a short
+middle process, which may have extended into the
+pit in the base of the carpal bone; while the distal
+terminal end is rounded exactly like a pulley. There
+is great difference in the length of the metacarpus.
+In the American genus Ornithostoma it is much
+longer than the fore-arm. In Rhamphorhynchus it
+is remarkably short, though perhaps scarcely so
+short as in Dimorphodon or in Scaphognathus. The
+largest Cretaceous examples are about two inches
+wide where they join the carpus. The bone is sometimes
+a little curved.</p>
+
+<p>Between the first and fifth or wing metacarpal are
+the three slender metacarpal bones which give attachment
+to the clawed digits. They bear much the
+same relation to the wing metacarpal that the large
+metatarsal of a Kangaroo has to the slender bones
+of the instep which are parallel to it.</p>
+
+<p>The facet for the wing metacarpal on the carpus is
+clearly recognised, but as a rule there is no surface
+with which the small metacarpals can be separately
+articulated. One or two exceptional specimens from
+the Cambridge Greensand appear to have not only
+surfaces for the wing metacarpal, but two much
+smaller articular surfaces, giving attachment to
+smaller metacarpals; while in one case there appears
+<span class='pagenum'><a name="Page_127" id="Page_127">[Pg 127]</a></span>
+to be only one of these additional impressions. It
+is certain that all the animals from the Lias and
+Oolites have three clawed digits, but at present I
+have seen no evidence that there were three in the
+Cretaceous genera, though Professor Williston's statements
+and restoration appear to show that the
+toothless Pterodactyles have three. Another difference
+from the Oolitic types, according to Professor
+Williston, is in the length of the slender metacarpals
+of the clawed phalanges being about one-third that
+of the wing metacarpal, but this is probably due to
+imperfect ossification at the proximal end; for at the
+distal end the bones all terminated on the same level,
+showing that the four outer digits were applied to
+the ground to support the weight of the body. The
+corresponding bone in the Horse and Oxen is carried
+erect, so as to be in a vertical line with the bones of
+the fore-arm; and the same position prevails usually,
+though not invariably, with the corresponding bone
+in the hind limb, while in many clawed mammals the
+metacarpus and metatarsus are both applied upon the
+ground. In Pterodactyles the metatarsal bones are
+preserved in the rock in the same straight line with
+the smaller bones of the foot, or make an angle with
+the shin bone, leading to the conviction that the bones
+of the foot were applied to the ground as in Man,
+and sometimes as in the Dog, and were thus modified
+for leaping. Just as the human metacarpus is extended
+in the same line with the bones of the fore-arm,
+and the movement of jointing occurs where the
+fingers join the metacarpus, so Pterodactyles also
+had these bones differently modified in the fore and
+hind limbs for the functions of life. The result is to
+lengthen the fore limb as compared with the hind
+<span class='pagenum'><a name="Page_128" id="Page_128">[Pg 128]</a></span>
+limb by introducing into it an elevation above the
+ground which corresponds to the length of the metacarpus,
+always supposing that the animal commonly
+assumed the position of a quadruped when upon the
+earth's surface.</p>
+
+<p>This position of the metacarpus is a remarkable
+difference from Birds, because when the bird's wing
+is at rest it is folded into three portions. The upper
+arm bone extends backward, the bones of the fore-arm
+are bent upon it so as to extend forward, and
+then at the wrist the third portion, which includes
+the metacarpus and finger bones, is bent backward.
+So that the metacarpus in the Pterodactyle differs from
+birds in being in the same line as the bones of the
+fore-arm, whereas in birds it is in the same line with
+the digit bones of the hand. It is worthy of remark
+that in Bats, which are so suggestive of Pterodactyles
+in some features of the hand, the metacarpals and
+phalanges are in the same straight line; so that in
+this respect the bat is more like the bird. But Pterodactyles
+in the relation of these bones to flight are
+quite unlike any other animal, and have nothing in
+common with the existing animals named Reptiles.</p>
+
+
+<h4>THE HAND</h4>
+
+<p>From what has just been said it follows that the
+construction of the hand is unique. It may be contrasted
+with the foot of a bird. The bone which
+is called, in the language of anatomists, the tarso-metatarsus,
+and is usually free from feathers and
+covered with skin, is commonly carried erect in birds,
+so that the whole body is supported upon it; and
+from it the toes diverge outward. It is formed in
+birds of three separate bones blended together. In
+<span class='pagenum'><a name="Page_129" id="Page_129">[Pg 129]</a></span>
+the fore limb of the Pterodactyle the metacarpus
+has the same relation to the bones of the fore-arm
+that the metatarsus has to the corresponding bones
+of the leg in a bird. But the three metacarpal bones
+in the Pterodactyle remain distinct from each other,
+perhaps because the main work of that region of the
+skeleton has devolved upon the digit called the wing
+finger, which is not recognised in the bird. In the
+Pterodactyles from the Solenhofen Slate there is
+a progressive number of phalanges in the three small
+digits of the hand, which were applied to the ground.
+This number in the great majority of species follows
+the formula of two bones in the first, three bones in
+second, and four in the third; so that in the innermost
+of the clawed digits only one bone intervenes between
+the metacarpal and the claw. The fingers slightly
+increase in length with increase in number of bones
+which form them.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_45" id="Fig_45"></a>
+<span class="caption">FIG. 45. &nbsp;  CLAW PHALANGE FROM THE HAND IN ORNITHOCHEIRUS.<br />
+(Half natural size)</span>
+<img src="images/i_146.jpg" width="640" height="208" alt="FIG. 45." title="FIG. 45." />
+</div>
+
+
+<p>The terminal claw bones are unlike the claws of
+Birds or Reptiles. They are compressed from side to
+side, and extremely deep and strong, with evidence of
+powerful attachment for ligaments, so that they rather
+resemble in their form and large size the claws of
+some of the carnivorous fossil reptiles, often grouped
+as Dinosauria, such as have been termed Aristosuchus
+and Megalosaurus. In the hand of the
+Ostrich the first and second digits terminate in
+claws, while the third is without a claw. But these
+<span class='pagenum'><a name="Page_130" id="Page_130">[Pg 130]</a></span>
+claws of the Ostrich and other birds are slender,
+curved, and rather feeble organs. In the Arch&aelig;opteryx,
+a fossil bird which agrees with the Pterodactyles
+in retaining the separate condition of the metacarpal
+bones and in having the same number of phalanges
+in two of the fingers of the fore limb, the terminal
+claws are rather more compressed from side to side,
+and stronger than in the Ostrich, but not nearly so
+strong as in the Pterodactyle. The Arch&aelig;opteryx
+differs from the Pterodactyle in having no trace of a
+wing finger. The first metacarpal bone is short,
+as in all birds; and the first phalange scarcely
+lengthens that segment of the first digit of the Bird's
+hand to the same length as the other metacarpal
+bones. It therefore was not bent backward like the
+first digit in Pterodactyles. The wing finger, from
+which the genius of Cuvier selected the scientific
+name&mdash;Pterodactyle&mdash;for these fossils, yields their
+<span class='pagenum'><a name="Page_131" id="Page_131">[Pg 131]</a></span>
+most distinctive character. It is a feature which could
+only be partly paralleled in the Bat, by making
+changes of structure which would remove every
+support to the wing but the outermost digit of that
+animal's hand. In the Bat's hand the membrane for
+flight is extended chiefly by four diverging metacarpal
+bones. There are only two or three phalanges in each
+digit in its four wing fingers. In Pterodactyles the
+metacarpal bones are, as we have seen, arranged in
+close contact, and take no part in stretching the wing.</p>
+
+
+<div class="figcenter" style="width: 599px;">
+<a name="Fig_46" id="Fig_46"></a>
+<span class="caption">FIG. 46. &nbsp;  METACARPUS AND DIGITS OF THE HAND
+IN BIRDS WITH CLAWS</span>
+<img src="images/i_147.jpg" width="599" height="480" alt="FIG. 46." title="FIG. 46." />
+</div>
+
+
+
+<h4>THE WING FINGER</h4>
+
+<p>In Birds there is nothing whatever to represent the
+wing finger of the Pterodactyle, for it is an organ
+external to the finger bones of the bird, and contains
+four phalanges. The first phalange is quite different
+from the others. Its length is astonishing when compared
+with the small phalanges of the clawed fingers.
+The articular surface, which joins on to the wing
+metacarpal bone, is a concave articulation, which fits
+the pulley in which that bone ends. The pulley
+articulation admits of an extension movement in
+one direction only. Many specimens show the wing
+finger to be folded up so as to extend backward.
+The whole finger is preserved in other specimens
+straightened out so as to be in line with the metacarpus.
+This condition is well seen in Professor
+Marsh's specimen of Rhamphorhynchus, which has
+the wing membrane preserved, in which all bones
+of the fore-arm metacarpus and wing finger are
+extended in a continuous curve. The outer surface
+of the end of the first bone of the wing finger
+overlaps the wing metacarpal, so that a maximum
+of strength and resistance is provided in the bony
+<span class='pagenum'><a name="Page_132" id="Page_132">[Pg 132]</a></span>
+structures by which the wing is supported. There
+is, therefore, in flight only one angular bend in the
+limb, and that is between the upper arm bone and
+the fore-arm.</p>
+
+<p>An immense pneumatic foramen is situate in a
+groove on the under side of the upper end of the
+first phalange in Ornithocheirus, but is absent in
+specimens from the Kimeridge clay. This bone is
+long and stout. It terminates at the lower end in
+an obliquely truncated articular surface. Specimens
+occur in the Cambridge Greensand which are 2 inches
+broad at the upper end and nearly 1&frac12; inch wide at
+the lower end. An imperfect bone from the Chalk
+is 14&frac12; inches long. The bones are all flattened.
+Specimens from the Chalk of Kansas at Munich are
+28 inches long. The second phalange is concave at
+the upper articular end and convex in the longer
+direction at the lower end. The articular points of
+union between the several phalanges form prominences
+on the under side of the finger in consequence
+of the adjacent bones being a little widened at their
+junction. It should be mentioned that there is a
+proximal epiphysis or separate bone to the first
+phalange, adjacent to the pulley joint of the metacarpal
+bone, which is like the separate olecranon process
+of the ulna of the fore-arm. It sometimes comes
+away in specimens from the Chalk and Cambridge
+Greensand, leaving a large circular pit with a depressed
+narrow border. On the outer side of this
+process is a rounded boss, which may possibly have
+supported the bone, if it were applied to the ground
+with the wing folded up, like the wing of a Bat directed
+upward and backward at the animal's side.</p>
+
+<p>The four bones of the wing finger usually decrease
+<span class='pagenum'><a name="Page_133" id="Page_133">[Pg 133]</a></span>
+progressively in length, so that in Rhamphorhynchus,
+in which the length of the animal's head only slightly
+exceeds 3&frac12; inches, the first phalange is nearly as long,
+the second phalange is about 3&frac14; inches, the third 2&frac34;
+inches, and the fourth a little over 2 inches. Thus
+the entire length of the four phalanges slightly exceeds
+11 inches, or rather more than three times the
+length of the head. But the fore-arm and metacarpus
+in this type only measure 3 inches. Therefore the
+entire spread of wings could not have been more
+than 2 feet 9 inches.</p>
+
+<p>The largest Ornithosaur in which accurate measurements
+have been made is the toothless Pterodactyle
+Ornithostoma, also named Pteranodon, from North
+America. In that type the head appears to have
+been about 3 or 4 feet long, and the wing finger
+exceeded 5 feet; while the length of the fore-arm
+and metacarpus exceeded 3 feet. The width of the
+body would not have been more than 1 foot. The
+length of the short humerus, which was about
+11 inches, did not add greatly to the stretch of the
+wing; so that the spread of the wings as stretched
+in flight may be given as probably not exceeding
+17 or 18 feet. A fine example of the wing bones of
+this animal quite as large has been obtained by the
+(British Museum Natural History). Many years ago,
+on very fragmentary materials, I estimated the wings
+in the English Cretaceous Ornithocheirus as probably
+having a stretch of 20 feet in the largest specimens,
+basing the calculation partly upon the extent of the
+longest wings in existing birds relatively to their
+bones, and partly upon the size of the largest associated
+bones which were then known.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_134" id="Page_134">[Pg 134]</a></span></p>
+<h2><a name="CHAPTER_XII" id="CHAPTER_XII"></a><small>CHAPTER XII</small><br /><br />
+
+EVIDENCES OF THE ANIMAL'S
+HABITS FROM ITS REMAINS</h2>
+
+
+<p>Such are the more remarkable characters of the
+bones in a type of animal life which was more
+anomalous than any other which peopled the earth
+in the Secondary Epoch of geological time. Its
+skeleton in different parts resembles Reptiles, Birds,
+and Mammals; with modifications and combinations
+so singular that they might have been deemed impossible
+if Nature's power of varying the skeleton
+could be limited. Since Ornithosaurs were provided
+with wings, we may believe the animals to some extent
+to have resembled birds in habit. Their modes of
+progression were more varied, for the structures indicate
+an equal capacity for movement on land as a
+biped, or as a quadruped, with movement in the air.
+There is little evidence to support the idea that they
+were usually aquatic animals. The majority of birds
+which frequent the water have their bodies stored
+with fat and the bones of their extremities filled with
+marrow. And a bird's marrow bones are stouter and
+stronger than those which are filled with air. There
+are few, if any, bones of Pterodactyles so thick as to
+suggest the conclusion that they contained marrow,<span class='pagenum'><a name="Page_135" id="Page_135">[Pg 135]</a></span>
+and the bones of the extremities appear to have been
+constructed on the lightest type found among terrestrial
+birds. Their thinness, except in a few specimens
+from the Wealden rocks, is marvellous; and all the
+later Pterodactyles show the arrangement, as in birds,
+by which air from the lungs is conveyed to the
+principal bones. No Pterodactyle has shown any
+trace of the web-footed condition seen in birds which
+swim on the water, unless the diverging bones of the
+hind foot in Rhamphorhynchus supports that inference.
+The bones of the hind foot are relatively
+small, and if it were not that a bird stands easily
+upon one foot, might be considered scarcely adequate
+to support the animal in the position which terrestrial
+birds usually occupy. Yet, as compared with the
+length and breadth of the foot in an Ostrich, the toes
+of an Ornithosaur are seen to be ample for support.
+These facts appear to discourage the idea that the
+animals were equally at home on land and water, and
+in air.</p>
+
+<p>Some light may be thrown upon the animal's habits
+by the geological circumstances under which the
+remains are found. The Pterodactyle named Dimorphodon,
+from the Lias of the south of England, is
+associated with evidences of terrestrial land animals,
+the best known of which is Scelidosaurus, an armoured
+Dinosaur adapted by its limbs for progression
+on land. And the Pterodactyle Campylognathus,
+from the Lias of Whitby, is associated with trunks
+of coniferous trees and remains of Insects. So that
+the occurrence of Pterodactyles in a marine stratum
+is not inconsistent with their having been transported
+by streams from off the old land surface of the Lias,
+on which coniferous trees grew and Dinosaurs lived.<span class='pagenum'><a name="Page_136" id="Page_136">[Pg 136]</a></span></p>
+
+<p>Similar considerations apply to the occurrence of
+the Rhamphocephalus in the Stonesfield Slate of
+England. The deposit is not only formed in shallow
+water, but contains terrestrial Insects, a variety of
+land plants, and many Reptiles and other animals
+which lived upon land. The specimens from the
+Purbeck beds, again, are in strata which yield a
+multitude of the spoils of a nearly adjacent land
+surface; while the numerous remains found in the
+marine Solenhofen Slate in Germany are similarly
+associated with abundant evidences of varied types
+of terrestrial life. The evidence grows in force from
+its cumulative character. The Wealden beds, which
+yield many terrestrial reptiles and so much evidence
+of terrestrial vegetation, and shallow-water conditions
+of disposition, have afforded important Pterodactyle
+remains from the Isle of Wight and Sussex.</p>
+
+<p>The chief English deposit in which these fossils
+are found, the Upper Greensand, has afforded
+thousands of bones, battered and broken on a
+shore, where they have lain in little associated
+groups of remains, often becoming overgrown with
+small marine shells. Side by side with them are
+found bones of true terrestrial Lizards and Crocodiles
+of the type of the Gavial of the Indian rivers, many
+terrestrial Dinosaurs, and other evidences of land
+life, including fossil resins, such as are met with in
+the form of amber or copal at the present day.</p>
+
+<p>The great bones of Pterodactyles found in the
+Chalk of Kent, near Rochester, became entombed,
+beyond question, far from a land surface. There is
+nothing to show whether the animals died on land
+and were drifted out to sea like the timber which is
+found water-logged and sunken after being drilled by<span class='pagenum'><a name="Page_137" id="Page_137">[Pg 137]</a></span>
+the ship-worm (Teredo) of that epoch. Seeing the
+power of flight which the animal possessed, storms
+may have struck down travellers from time to time,
+when far from land.</p>
+
+<p>Evidence of habit of another kind may be found
+in their teeth. They are brightly enamelled, sharp,
+formidable; and are frequently long, overlapping the
+sides of the jaws. They are organs which are often
+better adapted for grasping than for tearing, as may
+be seen in the inclined teeth of Rhamphocephalus of
+the Stonesfield Slate; and better adapted for killing
+than tearing, from their piercing forms and cutting
+edges, in genera like Ornithocheirus of the Greensand.
+The manner in which the teeth were implanted and
+carried is better paralleled by the fish-eating crocodile
+of Indian rivers than by the flesh-eating crocodiles, or
+Muggers, which live indifferently in rivers and the
+sea. As the Kingfisher finds its food (see <a href="#Fig_20">Fig. 20</a>)
+from the surface of the water without being in the
+common sense of the term a water bird, so some
+Pterodactyles may have fed on fish, for which their
+teeth are well adapted, both in the stream and by the
+shore.</p>
+
+<p>A Pterodactyle's teeth vary a good deal in appearance.
+The few large teeth in the front of the jaw
+in Dimorphodon, associated with the many small
+vertical teeth placed further backward, suggest that
+the taking of food may have been a process requiring
+leisure, since the hinder teeth adapted to
+mincing the animal's meat are extremely small. The
+way in which the teeth are shaped and arranged
+differs with the genera. In Pterodactylus they are
+short and broad and few, placed for the most part
+towards the front of the jaws. Their lancet-shaped<span class='pagenum'><a name="Page_138" id="Page_138">[Pg 138]</a></span>
+form indicates a shear-like action adapted to dividing
+flesh. In the associated genus Rhamphorhynchus
+the teeth are absent from the extremity of the jaw,
+are slender, pointed, spaced far apart, and extend far
+backward. When the jaws of the Rhamphorhynchus
+are brought together there is always a gap between
+them in front, which has led to belief that the teeth
+were replaced by some kind of horny armature which
+has perished. In the long-nosed English type of
+Ornithocheirus the jaws are compressed together, so
+that the teeth of the opposite sides are parallel to
+each other, with the margins well filled with teeth,
+which are never in close contact, though occasionally
+closer and larger in front, in some of the forms with
+thick truncated snouts.</p>
+
+<p>It is not the least interesting circumstance of the
+dentition of Pterodactyles that, associated in the
+same deposits with these most recent genera with
+teeth powerfully developed, there is a genus named
+Ornithostoma from the resemblance of its mouth to
+that of a bird in being entirely devoid of teeth. It
+is scarcely possible to distinguish the remains of the
+toothed and toothless skeletons except in the dentary
+character of the jaws. There is no evidence that
+the toothless types ever possessed a tooth of any
+sort. They were first found in fragments in England
+in the Cambridge Greensand, but were afterwards
+met with in great abundance in the Chalk of Kansas,
+where the same animals were named Pteranodon.
+A jaw so entirely bird-like suggests that the digestive
+organs of Pterodactyles may in such toothless forms
+at least have been characterised by a gizzard, which
+is so distinctive of Birds. The absence of teeth in
+the Great Ant-eater and some other allied Mammals<span class='pagenum'><a name="Page_139" id="Page_139">[Pg 139]</a></span>
+has transferred the function which teeth usually perform
+to the stomach, one part of which becomes
+greatly thickened and muscular, adapting itself to
+the work which it has to perform. It is probable
+that the gizzard may be developed in relation to the
+necessities which food creates, since even Trout, feeding
+on the shell-fish in some Irish lochs, acquire such
+a thickened muscular stomach, and a like modification
+is recorded in other fishes as produced by
+food.</p>
+
+<p>Closely connected with an animal's habits is the
+protection to the body which is afforded by the skin.
+In Pterodactyles the evidence of the condition of
+the skin is scanty, and mostly negative. Sometimes
+the dense, smooth texture of the jaw bones indicates
+a covering like the skin of a Lizard or the hinder part
+of the jaw of a Bird. Some jaws from the Cambridge
+Greensand have the bone channeled over its
+surface by minute blood vessels which have impressed
+themselves into the bone more easily than
+into its covering. Thus in the species of Ornithocheirus
+distinguished as <i>microdon</i> the palate is
+absolutely smooth, while in the species named
+<i>mach&aelig;rorhynchus</i> it is marked by parallel impressed
+vascular grooves which diverge from the median
+line. This condition clearly indicates a difference in
+the covering of the bone, and that in the latter
+species the covering had fewer blood vessels and
+more horny protection than in the other. The tissue
+may not have been of firmer consistence than in the
+palate of Mammals. The extremity of the beak is
+often as full of blood vessels as the jaw of a Turtle
+or Crocodile.</p>
+<p><span class='pagenum'><a name="Page_140" id="Page_140">[Pg 140]</a></span></p>
+
+<h4>COVERING OF THE BODY</h4>
+
+<p>There is no trace even in specimens from the
+Solenhofen or Stonesfield Slate of any covering to
+the body. There are no specimens preserved like
+mummies, and although the substance of the wings
+is found there is no trace of fur or feathers, bones,
+or scales on the skin. The only example in which
+there is even an appearance suggesting feathers is in
+the beautiful Scaphognathus at Bonn, and upon portions
+of the wing membrane of that specimen are
+preserved a very few small short and apparently
+tubular bodies, which have a suggestive resemblance
+to the quills of small undeveloped feathers. Such
+evidences have been diligently sought for. Professor
+Marsh, after examining the wing membranes of his
+specimen of Rhamphorhynchus from Solenhofen,
+stated that the wings were partially folded and
+naturally contracted into folds, and that the surface
+of the tissue is marked by delicate stri&aelig;, which
+might easily be taken at first sight for a thin coating
+of hair. Closer investigation proved the markings
+to be minute wrinkles on the under surface of the
+wing membrane. This negative evidence has considerable
+value, because the Solenhofen Slate has
+preserved in the two known examples of the bird
+Arch&aelig;opteryx beautiful details of the structure of
+the larger feathers concerned in flight. It has preserved
+many structures far more delicate. There is,
+therefore, reason for believing that if the skin had
+possessed any covering like one of those found in
+existing vertebrate animals, it could scarcely have
+escaped detection in the numerous undisturbed skeletons
+of Pterodactyles which have been examined.<span class='pagenum'><a name="Page_141" id="Page_141">[Pg 141]</a></span></p>
+
+<p>The absence of a recognisable covering to the skin
+in a fossil state cannot be accepted as conclusive
+evidence of the temperature, habits, or affinities of
+the animal. Although Mammalia are almost entirely
+clothed with dense hair, which has never been
+found in a recognisable condition in a fossil state in
+any specimen of Tertiary age, one entire order, the
+Cetacea, show in the smooth hairless skins of Whales
+and Porpoises that the class may part with the
+typical characteristic covering without loss of temperature
+and without intelligible cause. That the absence
+of hair is not due to the aquatic conditions of rivers
+or sea is proved by other marine Mammals, like Seals,
+having the skin clothed with a dense growth of hair,
+which is not surpassed in any other order. The fineness
+of the growth of hair in Man gives a superficial
+appearance of the skin being imperfectly clothed,
+and a similar skin in a fossil state might give the
+impression that it was devoid of hair. There are
+many Mammals in which the skin is scantily clothed
+with hair as the animal grows old. Neither the
+Elephant nor the Armadillo in a fossil state would be
+likely to have the hair preserved, for the growth is
+thin on the bony shields of the living Armadilloes.
+Yet the difficulty need be no more inherent in the
+nature of hair than in that of feathers, since the hair
+of the Mammoth and Rhinoceros has been completely
+preserved upon their skins in the tundras of
+Siberia, densely clothing the body. This may go
+to show that the Pterodactyle possessed a thin
+covering of hair, or, more probably, that hair
+was absent. Since Reptiles are equally variable in
+the clothing of the skin with bony or horny plates,
+and in sometimes having no such protection, it may<span class='pagenum'><a name="Page_142" id="Page_142">[Pg 142]</a></span>
+not appear singular that the skin in Ornithosaurs has
+hitherto given no evidence of a covering. From
+analogy a covering might have been expected;
+feathers of Birds and hair of Mammals are non-conducting
+coverings suited to arrest the loss of heat.</p>
+
+<p>With the evidence, such as it is, of resemblance of
+Ornithosaurs to Birds in some features of respiration
+and flight, a covering to the skin might have been
+expected. Yet the covering may not be necessary
+to a high temperature of the blood. Since Dr. John
+Davy made his observations it has been known that
+the temperature of the Tunny, above 90&deg; Fahrenheit,
+is as warm as the African scaly ant-eater named the
+Pangolin, which has the body more amply protected
+by its covering. This illustration also shows that
+hot blood may be produced without a four-celled
+heart, with which it is usually associated, and that
+even if the skin in Pterodactyles was absolutely
+naked an active life and an abundant supply of blood
+could have given the animal a high temperature.</p>
+
+<p>The circumstance that in several individuals the
+substance of the wing membrane is preserved would
+appear to indicate either that it was exceptionally
+stout when there would have been small chance of
+resisting decomposition, or that its preservation is
+due to a covering which once existed of fur or down
+or other clothing substance, which has proved more
+durable than the skin itself.</p>
+
+<div class="figcenter" style="width: 556px;">
+<a name="Fig_48" id="Fig_48"></a>
+<span class="caption">FIG. 48. &nbsp;  REMAINS OF DIMORPHODON FROM THE LIAS OF LYME REGIS<br /><br />
+SHOWING THE SKULL, NECK, BACK AND SOME OF THE LONGER BONES OF THE SKELETON</span>
+<img src="images/i_161.jpg" width="556" height="1024" alt="FIG. 48." title="" />
+<p class="center"><i>From a slab in the British Museum (Natural History)</i></p>
+</div>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_143" id="Page_143">[Pg 143]</a></span></p>
+<h2><a name="CHAPTER_XIII" id="CHAPTER_XIII"></a><small>CHAPTER XIII</small><br /><br />
+
+ANCIENT ORNITHOSAURS FROM THE LIAS</h2>
+
+
+<p>Cuvier's discourse on the revolutions of the
+Earth made the Pterodactyle known to English
+readers early in the nineteenth century. Dr. Buckland,
+the distinguished professor of Geology at
+Oxford, discovered in 1829 a far larger specimen in
+the Lias of Lyme Regis, and it became known by a
+figure published by the Geological Society, and by the
+description in his famous Bridgewater Treatise, p. 164.
+This animal was tantalising in imperfect preservation.
+The bones were scattered in the clay, so as to give no
+idea of the animal's aspect. Knowledge of its limbs
+and body has been gradually acquired; and now, for
+some years, the tail and most parts of the skeleton
+have been well known in this oldest and most
+interesting British Pterodactyle.</p>
+
+<p>Sir Richard Owen after some time separated the
+fossil as a distinct genus, named Dimorphodon; for
+it was in many ways unlike the Pterodactyles described
+from Bavaria. The name Dimorphodon indicated
+the two distinct kinds of teeth in the jaws,
+a character which is still unparalleled among Pterodactyles
+of newer age. There are a few large pointed,
+<span class='pagenum'><a name="Page_144" id="Page_144">[Pg 144]</a></span>
+piercing and tearing teeth in the front of the jaws,
+with smaller teeth further back, placed among the
+tearing teeth in the upper jaw; while in the lower
+jaw the small teeth are continuous, close-set, and
+form a fine cutting edge like a saw.</p>
+
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_49" id="Fig_49"></a>
+<span class="caption">FIG. 49. &nbsp; LEFT SIDE OF DIMORPHODON (RESTORED) AT REST</span>
+<img src="images/i_163.jpg" width="1024" height="470" alt="FIG. 49." title="FIG. 49." />
+</div>
+
+<p>The Dimorphodon has a short beak, a deep head,
+and deep lower jaw, which is overlapped by the cheek
+bones. The side of the head is occupied by four
+vacuities, separated by narrow bars of bone. First, in
+front, is the immense opening for the nostril, triangular
+in form, with the long upper side following the rounded
+curve of the face. A large triangular opening intervenes
+between the nose hole and the eye hole, scarcely
+smaller than the former, but much larger than the
+orbit of the eye. The eye hole is shaped like a kite
+or inverted pear. Further back still is a narrower vertical
+opening known as the lateral or inferior temporal
+vacuity. The back of the head is badly preserved.
+The two principal skulls differ in depth, probably
+from the strains under which they were pressed flat
+in the clay. A singular detail of structure is found
+in the extremity of the lower jaw, which is turned
+slightly downward, and terminates in a short toothless
+<span class='pagenum'><a name="Page_145" id="Page_145">[Pg 145]</a></span>
+point. The head of Dimorphodon is about eight inches
+long.</p>
+
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_50" id="Fig_50"></a>
+<span class="caption">FIG. 50. &nbsp; DIMORPHODON MACRONYX<br /><br />
+RESTORED FORM OF THE ANIMAL</span>
+<img src="images/i_165.jpg" width="1024" height="523" alt="FIG. 50." title="FIG. 50." />
+</div>
+
+<p>The neck bones are of suitable stoutness and width
+to support the head. The bones are yoked together
+by strong processes. The neck was about 6 inches
+long, did not include more than seven bones, and
+appeared short owing only to the depth and size of
+the head. The length of the backbone which supported
+the ribs was also about 6 inches. Its joints
+are remarkably short when compared with those of
+the neck. The tail is about 20 inches long.</p>
+
+<p>The extreme length of the animal from the tip
+of the nose to the end of the tail may have been
+3 feet 4 inches, supposing it to have walked on all
+fours in the manner of a Reptile or Mammal. This
+may have been a common position, but Dimorphodon
+may probably also have been a biped. Before
+1875, when the first restoration appeared in the
+<i>Illustrated London News</i>, the legs had been regarded
+as too short to have supported the animal, standing
+upon its hind limbs. They are here seen to be well
+adapted for such a purpose. The upper leg bone is
+3&frac14; inches long, the lower leg bone is 4&frac12; inches
+long, and the singularly strong instep bones are
+firmly packed together side by side as in a leaping
+or jumping Mammal, and measure 1&frac12; inches
+in length. Dimorphodon differs from several other
+Pterodactyles in having the hind limb provided
+with a fifth outermost short instep bone, to which
+two toe bones are attached. These bones are elongated
+in a way that may be compared, on a small
+scale, with the elongation of the wing finger in the
+fore limb. The digit was manifestly used in the same
+way as the wing finger, in partial support of a flying
+<span class='pagenum'><a name="Page_146" id="Page_146">[Pg 146]</a></span>
+membrane, though its direction may have been upward
+and outward, rather than inward. There is no
+evidence of a pulley joint between the metatarsal
+and the adjacent phalange.</p>
+
+<p>The height of the Dimorphodon, standing on its
+hind legs in the position of a Bird, with the wings
+folded upon the body in the manner of a Bird, was
+about 20 inches. An ungainly, ill-balanced animal
+in aspect, but not more so than many big-headed
+birds, and probably capable of resting upon the instep
+bones as many birds do. The chief point of variation
+from the Pterodactyle wing is in the relative
+length of the metacarpus in Dimorphodon. It is
+shorter than the other bones in the wing, never
+exceeding 1&frac12; inches. The total length of all
+the arm bones down to the point where the metacarpus
+might have touched the ground, or where
+the wing finger is bent upon it, is about 9 inches,
+which gives a length of less than 6 inches below
+the upper arm bone. The four bones of the wing
+finger measure, from the point where the first bone
+bends upon the metacarpus, less than 18 inches.
+So that the wings could only have been carried
+in the manner of the wings of a Bat, folded at the
+side and directed obliquely over the back when the
+animal moved on all fours. Its body would appear
+to have been raised high above the ground, in a
+manner almost unparalleled in Reptiles, and comparable
+to Birds and Mammals. Dimorphodon is to
+be imagined in full flight, with the body extended
+like that of a Bird, when the wings would have
+had a spread from side to side of about 4 feet 4
+inches. As in other animals of this group, the three
+claws on the front feet are larger than the similar
+four claws on the hind feet; as though the fingers
+might have functions in grasping prey, which were
+not shared by the toes.</p>
+
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_51" id="Fig_51"></a>
+<span class="caption">FIG. 51. &nbsp; DIMORPHODON MACRONYX WALKING AS A QUADRUPED<br /><br />
+RESTORATION OF THE SKELETON</span>
+<img src="images/i_168.jpg" width="1024" height="538" alt="FIG. 51." title="FIG. 51." />
+</div>
+
+<p><span class='pagenum'><a name="Page_147" id="Page_147">[Pg 147]</a></span>The
+restorations give faithful pictures of the skeleton,
+and the form of the body is built upon the indications
+of muscular structure seen in the bones.</p>
+
+
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_52" id="Fig_52"></a>
+<span class="caption">FIG. 52. &nbsp;  DIMORPHODON MACRONYX WALKING AS A BIPED</span>
+<p class="center"><i>Based chiefly on remains in the British Museum</i></p>
+<img src="images/i_172.jpg" width="1024" height="650" alt="FIG. 52." title="FIG. 52." />
+</div>
+
+<p>A second English Pterodactyle is found in the
+Upper Lias of Whitby. It is only known from
+an imperfect skull, published in 1888. It has the
+great advantage of preserving the bones in their
+natural relations to each other, and with a length of
+head probably similar to Dimorphodon shows that
+the depth at the back of the eye was much less; and
+the skull wants the arched contour of face seen in
+Dimorphodon. The head has the same four lateral
+vacuities, but the nostril is relatively small and elongated,
+extending partly above the oval antorbital
+opening, which was larger. There is thus a difference
+of proportion, but it is precisely such as might result
+from the species having the skull flatter. The head
+is easily distinguished by the small nostril, which
+is smaller than the orbit of the eye. The animal
+is referred to another genus. The quadrate bones
+which give attachment to the lower jaw send a process
+inward to meet the bones of the palate, which differ
+somewhat from the usual condition. Two bony rods
+extend from the quadrate bones backward and upward
+to the sphenoid, and two more slender bones
+extend from the quadrate bones forward, and converge
+in a <b>V</b>-shape, to define the division between
+the openings of the nostrils on the palate. The
+<b>V</b>-shaped bone in front is called the vomer, while
+the hinder part is called pterygoid. The bones that
+extend backward to the sphenoid are not easily identified.
+<span class='pagenum'><a name="Page_148" id="Page_148">[Pg 148]</a></span>
+This animal is one of the most interesting
+of Pterodactyles from the very reptilian character
+exhibited in the back of the head, which appears to
+be different from other specimens, which are more
+like a bird in that region. Yet underneath this
+reptilian aspect, with the bony bar at the side of the
+temporal region of the head formed by the squamosal
+and quadrate bones, defining the two temporal vacuities
+as in Reptiles, a mould is preserved of the
+cavity once occupied by the brain, showing the chief
+details of structure of that organ, and proving that
+in so far as it departs from the brain of a Bird it
+appears to resemble the brain of a Mammal, and is
+unlike the brain of a Reptile.</p>
+
+<p>The Pterodactyles from the Lias of Germany are
+similar to the English types, in so far as they can be
+compared. In 1878 I had the opportunity of studying
+those which were preserved in the Castle at Banz,
+which Professor Andreas Wagner, in 1860, referred to
+the new genus Dorygnathus. The skull is unknown,
+but the lower jaw, 6&frac12; inches long, is less than 2&frac12; inches
+wide at the articulation with the quadrate bone in the
+skull. The depth of the lower jaw does not exceed
+&frac14; inch, so that it is in marked contrast to Buckland's
+Dimorphodon. The symphysis, which completely
+blends the rami of the jaw, is short. As far as it
+extends it contains large tearing teeth, followed by
+smaller teeth behind, like those of Dimorphodon.
+But this German fossil appears to differ from the
+English type in having the front of the lower jaw, for
+about &frac34; inch, compressed from side to side into a
+sharp blade or spear, more marked than in any
+other Pterodactyle, and directed <i>upward</i> instead of
+downward as in Dimorphodon.  Nearly all the
+<span class='pagenum'><a name="Page_149" id="Page_149">[Pg 149]</a></span>
+measurements in the skeleton are practically identical
+with those of the English Dimorphodon, and
+extend to the jaw, humerus, ulna and radius, wing
+metacarpal, first phalange of the wing finger. The
+principal bones of the hind limb appear to be a little
+shorter; but the scapula and coracoid are slightly
+larger. All these bones are so similar in form to
+Dimorphodon that they could not be separated from
+the Lyme Regis species, if they were found in the
+same locality.</p>
+
+
+<div class="figcenter" style="width: 558px;">
+<a name="Fig_53" id="Fig_53"></a>
+<span class="caption">FIG. 53. &nbsp; LOWER JAW OF DORYGNATHUS SEEN FROM BELOW</span>
+<p class="center">From the Lower Lias of Germany, showing the spear in front
+of the tooth sockets</p>
+<img src="images/i_174.jpg" width="558" height="480" alt="FIG. 53." title="FIG. 53." />
+</div>
+
+<p>Just as the Upper Lias in England has yielded a
+second Pterodactyle, so the Upper Lias in Germany
+has yielded a skeleton, to which Felix Plieninger, in
+1894, gave the name Campylognathus. It is an instructive
+skeleton, with the head much smaller than
+in Dimorphodon, being less than 6 inches long, but,
+unfortunately, broken and disturbed. A lower jaw
+<span class='pagenum'><a name="Page_150" id="Page_150">[Pg 150]</a></span>
+gives the length 4&frac12; inches. Like the other Pterodactyles
+from the Lias, it has the extremity of the
+beak toothless, with larger teeth in the region of the
+symphysis in front and smaller teeth behind. The jaw
+is deeper than in the Banz specimen from the Lower
+Lias, but not so deep as in Dimorphodon. The teeth
+of the upper jaw vary in size, and there appears to
+be an exceptionally large tooth in the position of
+the Mammalian canine at the junction of the bones
+named maxillary and intermaxillary.</p>
+
+<p>The nasal opening is small and elongated, as in the
+English specimen from Whitby. As in that type
+there is little or no indication of the convex contour
+of the face seen in Dimorphodon.</p>
+
+<p>The neck does not appear to be preserved. In the
+back the vertebr&aelig; are about <sup>3</sup>/<sub>10</sub> inch long, so that
+twelve, which is the usual number, would only occupy
+a length of a little more than 3&frac12; inches. The tail is
+elongated like that of Dimorphodon, and bordered
+in the same way by ossified ligaments. There are
+thirty-five tail vertebr&aelig;. Those which immediately
+follow the pelvis are short, like the vertebr&aelig; of the
+back. But they soon elongate, and reach a maximum
+length of nearly 1&frac12; inches at the eighth, and
+then gradually diminish till the last scarcely exceeds
+<sup>1</sup>/<sub>8</sub> inch in length. The length of the tail is
+about 22 inches; this appears to be an inch or
+two longer than in Dimorphodon. The longest rib
+measures 2&frac12; inches, and the shortest 2 inches. These
+ribs probably were connected with the sternum, which
+is imperfectly preserved.</p>
+
+
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_54" id="Fig_54"></a>
+<span class="caption">FIG. 54. &nbsp;  DIMORPHODON MACRONYX<br /><br />
+SHOWING THE MAXIMUM SPREAD OF THE WING MEMBRANES</span>
+<img src="images/i_176.jpg" width="1024" height="588" alt="FIG. 54." title="FIG. 54." />
+</div>
+
+<p>The bones of the limbs have about the same length
+as those of Dimorphodon, so far as they can be compared,
+except that the ulna and radius are shorter.
+<span class='pagenum'><a name="Page_151" id="Page_151">[Pg 151]</a></span>
+The wing metacarpal is of about the same length,
+but the first phalange of the wing finger measures
+6&frac14; inches, the second is about 8&frac14; inches, the third
+6&frac12; inches, and the fourth 4&frac34; inches; so that the total
+length of the wing finger was about half an inch short
+of 2 feet. One character especially deserves attention
+in the apparent successive elongation of the first three
+phalanges in the wing finger in Dimorphodon. The
+third phalange is the longest in the only specimen in
+which the finger bones are all preserved. Usually the
+first phalange is much longer than the second, so that
+it is a further point of interest to find that this German
+type shares with Dimorphodon a character of
+the wing finger which distinguishes both from some
+members of the group by its short first phalange.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_55" id="Fig_55"></a>
+<span class="caption">FIG. 55. &nbsp; THE LEFT SIDE OF THE PELVIS OF DIMORPHODON
+SHOWING THE TWO PREPUBIC BONES</span>
+<img src="images/i_178.jpg" width="640" height="398" alt="FIG. 55." title="FIG. 55." />
+</div>
+
+<p>The pelvis is exceptionally strong in Campylognathus,
+and although it is crushed the bones manifestly
+met at the base of the ischium, while the pubic
+bones were separated from each other in front. The
+bones of the hind limb are altogether shorter in the
+German fossil than in Dimorphodon, especially in
+<span class='pagenum'><a name="Page_152" id="Page_152">[Pg 152]</a></span>
+the tibia; but the structure of the metatarsus is just
+the same, even to the short fifth metatarsal with its
+two digits, only those bones are extremely short, instead
+of being elongated as in Dimorphodon. It is
+therefore convenient, from the different proportions
+of the body, that Campylognathus may be separated
+from Dimorphodon; but so much as is preserved of
+the English specimen from the Upper Lias of Whitby
+rather favours the belief that our species should also
+be referred to Campylognathus, which had not been
+figured when the Whitby skull was referred to Scaphognathus
+by Mr. Newton. It may be doubtful whether
+there is sufficient evidence to establish the distinctness
+of the other German genus Dorygnathus, though
+it may be retained pending further knowledge.</p>
+
+<p>In these characters are grounds for placing the
+Lias Pterodactyles in a distinct family, the Dimorphodontid&aelig;,
+as was suggested in 1870. This evidence
+is found in the five metatarsal bones, of which four
+are in close contact, the middle two being slightly
+the longest, so as to present the general aspect of the
+corresponding bones in a Mammal rather than a Bird.
+Secondly, the very slender fibula, prolonged down the
+length of the shin bone, which ends in a rounded
+pulley like the corresponding bone of a Bird. Thirdly,
+the great elongation of the third wing phalange.
+Fourthly, the prolongation of the coracoid bone beyond
+the articulation for the humerus, as in a Bird.
+And the toothless, spear-shaped beak, and jaw with
+large teeth in front and small teeth behind, are also
+distinctive characters.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_153" id="Page_153">[Pg 153]</a></span></p>
+<h2><a name="CHAPTER_XIV" id="CHAPTER_XIV"></a><small>CHAPTER XIV</small><br /><br />
+
+ORNITHOSAURS FROM THE
+MIDDLE SECONDARY ROCKS</h2>
+
+
+<h4>RHAMPHOCEPHALUS</h4>
+
+<p>The Stonesfield Slate in England, which corresponds
+in age with the lower part of the Great
+or Bath Oolite, yields many evidences of terrestrial
+life&mdash;land plants, insects, and mammals&mdash;preserved in
+a marine deposit. A number of isolated bones have
+been found of Pterodactyles, some of them indicating
+animals of considerable size and strength. The
+nature of the limestone was unfavourable to the preservation
+of soft wing membranes, or even to the bones
+remaining in natural association. Very little is known
+of the head of Rhamphocephalus. One imperfect specimen
+shows a long temporal region which is wide, and
+a very narrow interspace between the orbits; with a
+long face, indicated by the extension of narrow
+nasal bones. The lower jaw has an edentulous beak
+or spear in front, which is compressed from side to
+side in the manner of the Liassic forms, but turned
+upward slightly, as in Dorygnathus or Campylognathus.
+Behind this extremity are sharp, tall teeth,
+few in number, which somewhat diminish in size as
+they extend backward, and do not suddenly change
+<span class='pagenum'><a name="Page_154" id="Page_154">[Pg 154]</a></span>
+to smaller series, as in the Lias genera. A few small
+vertebr&aelig; have been found, indicating the neck and
+back. The sacrum consists of five vertebr&aelig;. One
+small example has a length of only an inch. It is
+a little narrower behind than in front, and would be
+consistent with the animal having had a long tail,
+which I believe to have been present, although I
+have not seen any caudal vertebr&aelig;. The early ribs
+are like the early ribs of a Crocodile or Bird in the
+well-marked double articulation. The later ribs
+appear to have but one head. <b>V</b>-shaped abdominal
+ribs are preserved. Much of the animal is unknown.
+The coracoid seems to have been directed forward,
+and, as in a bird, it is 2&frac12; inches long. The humerus
+is 3&frac12; inches long, and the fore-arm measured 6
+inches, so that it was relatively longer than in Dimorphodon.
+The metacarpus is 1&frac34; inches long. The
+wing finger was exceptionally long and strong. Professor
+Huxley gave its length at 29 inches. My own
+studies lead to the conclusion that the first finger
+bone of the wing was the shorter, and that although
+they did not differ greatly in length, the second was
+probably the longest, as in Campylognathus.</p>
+
+<p>Professor Huxley makes the second and third
+phalanges 7&frac34; inches long, and the first only about
+<sup>3</sup>/<sub>8</sub> inch shorter, while the fourth phalange is 6&frac12; inches.
+These measurements are based upon some specimens
+in the Oxford University Museum. There is only
+one first phalange which has a length of 7&frac34; inches.
+The others are between 5 and 6 inches, or but little
+exceed 4 inches; so that as all the fourth phalanges
+which are known have a length of 6&frac12; inches, it is
+possible that the normal length of the first phalange
+in the larger species was 5&frac12; inches. The largest
+<span class='pagenum'><a name="Page_155" id="Page_155">[Pg 155]</a></span>
+of the phalanges which may be classed as second or
+third is 8&frac12; inches, and that, I suppose, may have been
+associated with the 7&frac34; inches first phalange. But
+the other bones which could have had this position
+all measure 5&frac12; and 7&frac34; inches. The three species
+indicated by finger bones may have had the measurements:&mdash;</p>
+
+<div class='center'>
+<table border="0" cellpadding="2" cellspacing="0" summary="">
+<tr><th align='center' colspan='4'>Phalanges of the wing finger</th></tr>
+<tr><td align='center'>I.</td><td align='center'>II.</td><td align='center'>III.</td><td align='center'>IV.</td></tr>
+<tr><td align='center'>7&frac34;</td><td align='center'>8&frac12;</td><td align='center'>[7?]</td><td align='center'>6&frac12;</td><td align='center' rowspan='3'><span class="ft30">}</span> length of each bone in inches.</td></tr>
+<tr><td align='center'>5&frac12;</td><td align='center'>7&frac34;</td><td align='center'>5&frac12;</td><td align='center'>[4&frac12;?]</td></tr>
+<tr><td align='center'>4&frac12;</td><td align='center'>&mdash;&mdash;</td><td align='center'>&mdash;&mdash;</td><td align='center'>&mdash;&mdash;</td></tr>
+</table></div>
+
+<p>The femur is represented by many examples&mdash;one
+3&frac34; inches long, and others less than 3 inches long
+(2<sup>9</sup>/<sub>10</sub>). In Campylognathus, which has so much in
+common with the jaw and the wing bones in size,
+the upper leg bone is 2<sup>8</sup>/<sub>10</sub> inches. Therefore if we
+assign the larger femur to the larger wing, the femur
+will be relatively longer in all species of Rhamphocephalus
+than in Campylognathus. Only one example
+of a tibia is preserved. It is 3&frac12; inches long,
+or only <sup>1</sup>/<sub>10</sub> inch shorter than the bone in Campylognathus,
+which has the femur 2<sup>8</sup>/<sub>10</sub> inches, so that I
+refer the tibia of Rhamphocephalus to the species
+which has the intermediate length of wing. These
+coincidences with Campylognathus establish a close
+affinity, and may raise the question whether the
+Upper Lias species may not be included in the
+Stonesfield Slate genus Rhamphocephalus.</p>
+
+<p>The late Professor Phillips, in his <i>Geology of Oxford</i>,
+attempted a restoration of the Stonesfield Ornithosaur,
+and produced a picturesque effect (<a href="#Page_164">p. 164</a>); but
+no restoration is possible without such attention to
+the proportions of the bones as we have indicated.</p>
+<p><span class='pagenum'><a name="Page_156" id="Page_156">[Pg 156]</a></span></p>
+
+<h4>OXFORD CLAY</h4>
+
+<p>A few bones of flying reptiles have been found in
+the Lower Oxford Clay near Peterborough, and others
+in the Upper Oxford Clay at St. Ives, in Huntingdonshire.
+A single tail vertebra from the Middle Oxford
+Clay, near Oxford, long since came under my own
+notice, and shows that these animals belong to a
+long-tailed type like Campylognathus. The cervical
+vertebr&aelig; are remarkable for being scarcely longer than
+the dorsal vertebr&aelig;; and the dorsal are at least half
+as long again as is usual, having rather the proportion
+of bones in the back of a crocodile.</p>
+
+
+<h4>LITHOGRAPHIC SLATE</h4>
+
+<p>Long-tailed Pterodactyles are beautifully preserved
+in the Lithographic Limestone of the south of Bavaria,
+at Solenhofen, and the quarries in its neighbourhood,
+often with the skeleton or a large part of it flattened
+out in the plane of bedding of the rock. Fine skeletons
+are preserved in the superb museum at Munich,
+at Heidelberg, Bonn, Haarlem, and London, and are
+all referred to the genus Rhamphorhynchus or to
+Scaphognathus. It is a type with powerfully developed
+wings and a long, stiff tail, very similar to
+that of Dimorphodon, so that some naturalists refer
+both to the same family. There is some resemblance.</p>
+
+<p>The type which is most like Dimorphodon is the
+celebrated fossil at Bonn, sometimes called <i>Pterodactylus
+crassirostris</i>, which in a restored form, with a
+short tail, has been reproduced in many text-books.
+No tail is preserved in the slab, and I ventured to
+give the animal a tail for the first time in a restoration
+(<a href="#Page_163">p. 163</a>) published by the <i>Illustrated London News</i>
+in 1875, which accompanied a report of a Royal
+<span class='pagenum'><a name="Page_157" id="Page_157">[Pg 157]</a></span>
+Institution lecture. Afterwards, in 1882, Professor
+Zittel, of Munich, published the same conclusion.
+The reason for restoring the tail was that the animal
+had the head constructed in the same way as
+Pterodactyles with a long tail, and showed differences
+from types in which the tail is short; and there
+is no known short-tailed Pterodactyle, with wrist
+and hand bones, such as characterise this animal.
+The side of the face has a general resemblance to
+the Pterodactyles from the Lias, for although the
+framework is firmer, the four apertures in the head
+are similarly placed. The nostril is rather small and
+elongated, and ascends over the larger antorbital
+vacuity. The orbit for the eye is the largest opening
+in the head, so that these three apertures successively
+increase in size, and are followed by the vertically
+elongated post-orbital vacuity. The teeth are widely
+spaced apart, and those in the skull extend some
+distance backward to the end of the maxillary bone.
+There are few teeth in the lower jaw, and they correspond
+to the large anterior teeth of Dimorphodon,
+there being no teeth behind the nasal opening. The
+lower jaw is straight, and the extremities of the
+jaws met when the mouth was closed. The breast
+bone does not show the keel which is so remarkable
+in Rhamphorhynchus, which may be attributed to
+its under side being exposed, so as to exhibit the
+pneumatic foramina.</p>
+
+<p>The ribs have double heads, more like those of a
+Crocodile in the region of the back than is the case
+with the bird-like ribs from Stonesfield. The second
+joint in the wing finger may be longer than the first&mdash;a
+character which would tend to the association of
+this Pterodactyle with species from the Lias; a relation
+<span class='pagenum'><a name="Page_158" id="Page_158">[Pg 158]</a></span>
+to which attention was first drawn by Mr. E. T. Newton,
+who described the Whitby skull.</p>
+
+<p>The Pterodactyles from the Solenhofen Slate which
+possess long tails have a series of characters which show
+affinity with the other long-tailed types. The jaws are
+much more slender. The orbit of the eye in Rhamphorhynchus
+is enormously large, and placed vertically
+above the articulation for the lower jaw. Immediately
+in front of the eye are two small and elongated openings,
+the hinder of which, known as the antorbital
+vacuity, is often slightly smaller than the nostril, which
+is placed in the middle length of the head, or a little
+further back, giving a long dagger-shaped jaw, which
+terminates in a toothless spear. The lower jaw has
+a corresponding sharp extremity. The teeth are
+directed forward in a way that is quite exceptional.
+Notwithstanding the massiveness and elongation of
+the neck vertebr&aelig;, which are nearly twice as long as
+those of the back, the neck is sometimes only about
+half the length of the skull.</p>
+
+<p>All these long-tailed species from the Lithographic
+Stone agree in having the sternum broad, with a long
+strong keel, extending far forward. The coracoid
+bones extend outward like those of a Crocodile, so
+as to widen the chest cavity instead of being carried
+forward as the bones are in Birds. These bones in this
+animal were attached to the anterior extremity of the
+sternum, so that the keel extended in advance of the
+articulation as in other Pterodactyles. The breadth
+of the sternum shows that, as in Mammals, the fore
+part of the body must have been fully twice the
+width of the region of the hip-girdle, where the
+slenderer hind limbs were attached. The length
+of the fore limb was enormous, for although the head
+<span class='pagenum'><a name="Page_159" id="Page_159">[Pg 159]</a></span>
+suggests an immense length relatively to the body,
+nearly equal to neck and back together, the head is
+not more than a third of the length of the wing
+bones. The wing bones are remarkable for the short
+powerful humerus with an expanded radial crest,
+which is fully equal in width to half the length of the
+bone. Another character is the extreme shortness
+of the metacarpus, usually associated with immense
+strength of the wing metacarpal bone.</p>
+
+<p>The hind limbs are relatively small and relatively
+short. The femur is usually shorter than the humerus,
+and the tibia is much shorter than the ulna. The
+bones of the instep, instead of being held together
+firmly as in the Lias genera, diverge from each other,
+widening out, though it often happens that four of
+the five metatarsals differ but little in length. The
+fifth digit is always shorter.</p>
+
+<p>The hip-girdle of bones differs chiefly from other
+types in the way in which those bones, which have
+sometimes been likened to the marsupial bones, are
+conditioned. They may be a pair of triangular bones
+which meet in the middle line, so that there is an
+outer angle like the arm of a capital Y. Sometimes
+these triangular bones are blended into a curved,
+bow-shaped arch, which in several specimens appears
+to extend forward from near the place of articulation
+of the femur. This is seen in fossil skeletons at
+Heidelberg and Munich. It is possible that this
+position is an accident of preservation, and that the
+prepubic bones are really attached to the lower
+border of the pubic bones.</p>
+
+<p>Immense as the length of the tail appears to be,
+exceeding the skull and remainder of the vertebral
+column, it falls far short of the combined length of the
+<span class='pagenum'><a name="Page_160" id="Page_160">[Pg 160]</a></span>
+phalanges of the wing finger. The power of flight
+was manifestly greater in Rhamphorhynchus than in
+other members of the group, and all the modifications
+of the skeleton tend towards adaptation of the
+animals for flying. The most remarkable modification
+of structure at the extremity of the tail was made
+known by Professor Marsh in a vertical, leaf-like
+expansion in this genus, which had not previously
+been observed (<a href="#Page_161">p. 161</a>). The vertebr&aelig; go on steadily
+diminishing in length in the usual way, and then
+the ossified structures which bordered the tail bones
+and run parallel with the vertebr&aelig; in all the Rhamphorhynchus
+family, suddenly diverge downward and
+upward at right angles to the vertebr&aelig;, forming a
+vertical crest above and a corresponding keel below;
+and between these structures, which are identified
+with the neural spines and chevron bones of ordinary
+vertebr&aelig;, the membrane extends, giving the extremity
+of the tail a rudder-like feature, which, from knowledge
+of the construction of the tail of a child's kite,
+may well be thought to have had influence in directing
+and steadying the animal's movements. There
+are many minor features in the shoulder-girdle, which
+show that the coracoid, for example, was becoming
+unlike that bone in the Lias, though it still continues
+<span class='pagenum'><a name="Page_161" id="Page_161">[Pg 161]</a></span>
+to have a bony union with the elongated shoulder-blade
+of the back.</p>
+
+
+<p><span class='pagenum'><a name="Page_162" id="Page_162">[Pg 162]</a></span></p>
+
+<div class="figcenter" style="width: 1024px;">
+<a name="Fig_56" id="Fig_56"></a>
+<span class="caption">FIG. 56. &nbsp;  RESTORATION OF THE SKELETON OF <i>RHAMPHORHYNCHUS PHYLLURUS</i></span>
+<p class="center">From the Solenhofen Slate, partly based upon the skeleton with the wing membranes preserved</p>
+<img src="images/i_188.jpg" width="1024" height="630" alt="FIG. 56." title="FIG. 56." />
+</div>
+
+
+
+<p><span class='pagenum'><a name="Page_163" id="Page_163">[Pg 163]</a></span></p>
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_57" id="Fig_57"></a>
+<span class="caption">FIG. 57. &nbsp;   RESTORATION OF THE SKELETON OF
+<i>SCAPHOGNATHUS CRASSIROSTRIS</i></span>
+<p class="center">Published in the <i>Illustrated London News</i> in 1875. In which a tail is
+shown on the evidence of the structure of the head and hand</p>
+<img src="images/i_190.jpg" width="640" height="408" alt="FIG. 57." title="FIG. 57." />
+</div>
+
+
+
+
+<p>The great German delineator of these animals, Von
+Meyer, admitted six different species. Mr. Newton
+and Mr. Lydekker diminish the number to four. It is
+not easy to determine these differences, or to say how
+far the differences observed in the bones characterise
+species or genera. It is certain that there is one
+remarkable difference from other and older Pterodactyles,
+in that the last or fourth bone in the wing
+finger is usually slightly longer than the third bone,
+which precedes it. There is a certain variability in
+the specimens which makes discussion of their
+characters difficult, and has led to some forms being
+regarded as varieties, while others, of which less
+material is available, are classed as species. I am
+disposed to say that some of the confusion may
+have resulted from specimens being wrongly named.
+Thus, there is a Rhamphorhynchus called curtimanus,
+or the form with the short hand. It is
+represented by two types. One of these appears to
+have the humerus short, the ulna and radius long,
+and the finger bones long; the other has the humerus
+longer, the ulna much shorter, and the finger bones
+shorter. They are clearly different species, but the
+second variety agrees in almost every detail with
+a species named hirundinaceus, the swallow-like
+Rhamphorhynchus. This identification shows, not
+<span class='pagenum'><a name="Page_164" id="Page_164">[Pg 164]</a></span>
+that the latter is a bad species, but that curtimanus
+is a distinct species which had sometimes been confounded
+with the other. While most of these
+specimens show a small but steady decrease in the
+length of the several wing finger bones, the species
+called Gemmingi has the first three bones absolutely
+equal and shorter than in the species curtimanus,
+longimanus, or hirundinaceus. In the same way,
+on the evidence of facts, I find myself unable to join
+in discarding Professor Marsh's species phyllurus,
+on account of the different proportions of its limb
+bones. The humerus, metacarpus, and third phalange
+<span class='pagenum'><a name="Page_165" id="Page_165">[Pg 165]</a></span>
+of the wing finger in <i>Rhamphorhynchus phyllurus</i>
+are exceptionally short as compared with other
+species. Everyone agrees that the species called
+longicaudus is a distinct one, so that it is chiefly in
+slight differences in the proportions of constituent
+parts of the skeleton that the types of the Rhamphorhynchus
+are distinguished from each other.
+I cannot quite concur with either Professor Zittel
+(<a href="#Fig_58">Fig. 58, 3</a>) or Professor Marsh (<a href="#Fig_58">Fig. 58, 2</a>) in the
+expansion which they give to the wing membrane
+in their restorations; for although Professor Zittel
+represents the tail as free from the hind legs, while
+Professor Marsh connects them together, they both
+concur in carrying the wing membrane from the
+tip of the wing finger down to the extremity of the
+ankle joint. I should have preferred to carry it no
+further down the body than the lower part of the
+back, there being no fossil evidence in favour of this
+extension so far as specimens have been described.
+Neither the membranous wings figured by Zittel nor
+by Marsh would warrant so much body membrane as
+the Rhamphorhynchus has been credited with. I
+have based my restoration (<a href="#Page_161">p. 161</a>) of the skeleton
+chiefly on <i>Rhamphorhynchus phyllurus.</i></p>
+
+
+<div class="figcenter" style="width: 600px;">
+<a name="Fig_58" id="Fig_58"></a>
+<span class="caption">FIG. 58. &nbsp; SIX RESTORATIONS</span>
+<img src="images/i_191.jpg" width="600" height="620" alt="FIG. 58." title="FIG. 58." />
+<p class="noidt">
+1. Ramphocephalus. Stonesfield Slate. John Phillips, 1871<br />
+2. Rhamphorhynchus. O. C. Marsh, 1882<br />
+3. Rhamphorhynchus. V. Zittel, 1882<br />
+4. Ornithostoma. Williston, 1897<br />
+5. Dimorphodon. Buckland, 1836. Tail then unknown<br />
+6. Ornithocheirus. H. G. Seeley, 1865<br />
+</p>
+</div>
+
+
+
+<h4>THE SHORT-TAILED TYPES</h4>
+
+<p>The Pterodactylia are less variable; and the variation
+among the species is chiefly confined to relative
+length of the head, length of the neck, and the
+height of the body above the ground. The tail is
+always so short as to be inappreciable. Many of the
+specimens are fragmentary, and the characters of the
+group are not easily determined without careful
+comparisons and measurements. The bones of the
+<span class='pagenum'><a name="Page_166" id="Page_166">[Pg 166]</a></span>
+fore limb and wing finger are less stout than in
+the Rhamphorhynchus type, while the femur is
+generally a little longer than the humerus, and the
+wing finger is short in comparison with its condition
+in Rhamphorhynchus. These short-tailed Pterodactyles
+give the impression of being active little
+animals, having very much the aspect of birds, upon
+four legs or two. The neck is about as long as the
+lower jaw, the antorbital vacuity in the head is imperfectly
+separated from the much larger nasal opening,
+the orbit of the eye is large and far back, the
+teeth are entirely in front of the nasal aperture, and
+the post-orbital vacuity is minute and inconspicuous.
+The sternum is much wider than long, and no specimens
+give evidence of a manubrium. The finger
+bones progressively decrease in length. The prepubic
+bones have a partially expanded fan-like form,
+and never show the triradiate shape, and are never
+anchylosed. About fifteen different kinds of Pterodactyles
+have been described from the Solenhofen
+Slate, mostly referred to the genus Pterodactylus,
+which comprises forms with a large head and long
+snout. Some have been placed in a genus (Ornithocephalus,
+or Ptenodracon) in which the head
+is relatively short. The majority of the species
+are relatively small. The skull in <i>Ornithocephalus
+brevirostris</i> is only 1 inch long, and the animal
+could not have stood more than 1&frac12; inches to its back
+standing on all fours, and but little over 2&frac12; inches
+standing as a biped, on the hind limbs.</p>
+
+<p>A restoration of the species called <i>Pterodactylus
+scolopaciceps</i>, published in 1875 in the <i>Illustrated
+London News</i> in the position of a quadruped, shows
+an animal a little larger, with a body 2&frac12; inches high
+<span class='pagenum'><a name="Page_167" id="Page_167">[Pg 167]</a></span>
+and 6 to 7 inches long, with the wing finger 4&frac12; inches
+long. Larger animals occur in the same deposit, and
+in one named <i>Pterodactylus grandis</i> the leg bones
+are a foot long; and such an animal may have been
+nearly a foot in height to its back, standing as a
+quadruped, though most of these animals had the
+neck flexible and capable of being raised like the
+neck of a Goose or a Deer (<a href="#Page_30">p. 30</a>), and bent down
+like a Duck's when feeding.</p>
+
+<div class="figcenter" style="width: 877px;">
+<a name="Fig_59" id="Fig_59"></a>
+<span class="caption">FIG. 59. &nbsp;  RESTORATION OF THE SKELETON OF
+<i>PTENODRACON BREVIROSTRIS</i></span>
+<p  class="center">From the Solenhofen Slate. The fourth joint of the wing finger appears to
+be lost and has not been restored in the figure. (Natural size)</p>
+<img src="images/i_194.jpg" width="877" height="768" alt="FIG. 59." title="FIG. 59." />
+</div>
+
+
+<p>The type of the genus Pterodactylus is the form
+originally described by Cuvier as<i> Pterodactylus longirostris</i>
+(<a href="#Page_28">p. 28</a>). It is also known as <i>P. antiquus</i>, that
+name having been given by a German naturalist after
+Cuvier had invented the genus, and before he had
+<span class='pagenum'><a name="Page_168" id="Page_168">[Pg 168]</a></span>
+named the species. There are some remarkable
+features in which Cuvier's animal is distinct from
+others which have been referred to the same
+genus. Thus the head is 4&frac12; inches long, while
+the entire length of the backbone to the extremity
+of the tail is only 6&frac12; inches, and one
+vertebra in the neck is at least as long as six in
+the back, so that the animal has the greater part
+of its length in the head and neck, although the
+neck includes so few vertebr&aelig;. Nearly all the teeth&mdash;which
+are few in number, short and broad, not
+exceeding a dozen in either jaw&mdash;are limited to the
+front part of the beak, and do not extend anywhere
+near the nasal vacuity. This is not the case with all.</p>
+
+<p>In the species named <i>P. Kochi</i>, which I have regarded
+as the type of a distinct genus, there are
+large teeth in the front of the jaw corresponding to
+those of Pterodactylus, and behind these a smaller
+series of teeth extending back under the nostril,
+which approaches close to the orbit of the eye,
+without any indication of a separate antorbital
+vacuity. On those characters the genus Diopecephalus
+was defined. It is closely allied to Pterodactylus;
+both agree in having the ilium prolonged
+forward more than twice as far as it is carried backward,
+the anterior process covering about half a
+dozen vertebr&aelig;, as in <i>Pterodactylus longirostris</i>. A
+great many different types have been referred to
+<i>Pterodactylus Kochi</i>, and it is probable that they
+may eventually be distinguished from each other.
+The species in which the upper borders of the orbits
+approximate could be separated from those in which
+the frontal interspace is wider.</p>
+
+
+<div class="figcenter" style="width: 854px;">
+<a name="Fig_60" id="Fig_60"></a>
+<span class="caption">FIG. 60. &nbsp;  CYCNORHAMPHUS SUEVICUS FROM THE SOLENHOFEN SLATE
+SHOWING THE SCATTERED POSITION OF THE BONES</span>
+<p  class="center"><i>Original in the Museum at T&uuml;bingen</i></p>
+<img src="images/i_196.jpg" width="854" height="768" alt="FIG. 60." title="FIG. 60." />
+</div>
+
+
+<p><span class='pagenum'><a name="Page_169" id="Page_169">[Pg 169]</a></span></p>
+<div class="figcenter" style="width: 957px;">
+<a name="Fig_61" id="Fig_61"></a>
+<span class="caption">FIG. 61. &nbsp;  CYCNORHAMPHUS SUEVICUS<br /><br />
+RESTORATION SHOWING THE FORM OF THE BODY AND THE WING MEMBRANES</span>
+<img src="images/i_198.jpg" width="957" height="768" alt="FIG. 61." title="FIG. 61." />
+</div>
+
+
+<p>It is a remarkable feature in these animals that
+the middle bones of the foot, termed instep bones
+or metatarsals, are usually close together, so that
+the toes diverge from a narrow breadth, as in <i>P.
+longirostris</i>, <i>P. Kochi</i>, and other forms; but there
+also appear to be splay-footed groups of Pterodactyles
+like the species which have been named
+<i>P. elegans</i> and <i>P. micronyx</i>, in which the metatarsus
+widens out so that the bones of the toes do not
+diverge, and that condition characterises the Ptenodracon
+(<i>Pterodactylus brevirostris</i>), to which genus
+these species may possibly be referred. Nearly all
+who have studied these animals regard the singularly
+short-nosed species <i>P. brevirostris</i> as forming a
+separate genus. For that genus S&ouml;mmerring's descriptive
+name Ornithocephalus, which he used for
+Pterodactyles generally, might perhaps have been
+retained. But the name Ptenodracon, suggested by
+Mr. Lydekker, has been used for these types.</p>
+
+
+<p>Some of the largest specimens preserved at Stuttgart
+and T&uuml;bingen have been named <i>Pterodactylus
+suevicus</i> and <i>P. Fraasii</i>. They do not approach the
+species <i>P. grandis</i> in size, so far as can be judged
+from the fragmentary remains figured by Von Meyer;
+for what appears to be the third phalange of the
+wing finger is 7&frac12; inches long, while in these species
+it is less than half that length, indicating an enormous
+development of wing, relatively to the length
+of the hind limb, which would probably refer the
+species to another genus. <i>Pterodactylus suevicus</i>
+differs from the typical Pterodactyles in having a
+rounded, flattened under surface to the lower jaw,
+instead of the common condition of a sharp keel
+in the region of the symphysis. The beak also seems
+flattened and swan-like, and the teeth are limited to
+<span class='pagenum'><a name="Page_170" id="Page_170">[Pg 170]</a></span>
+the front of the jaw. There appear to be some
+indications of small nostrils, which look upward like
+the nostrils of Rhamphorhynchus, but this may be
+a deceptive appearance, and the nostrils are large
+lateral vacuities, which are in the position of antorbital
+vacuities, so that there would appear to be
+only two vacuities in the side of the head in these
+animals. The distinctive character of the skeleton in
+this genus is found in the extraordinary length
+of the metacarpus and in the complete ossification
+of the smaller metacarpal bones throughout their
+length. The metacarpal bones are much longer than
+the bones of the fore-arm, and about twice the length
+of the humerus. The first wing phalange is much
+longer than the others, which successively and rapidly
+diminish in length, so that the third is half the length
+of the first. There are differences in the pelvis; for
+the anterior process of the ilium is very short, in comparison
+with its length in the genus Pterodactylus.
+And the long stalk of the prepubic bone with its great
+hammer-headed expansion transversely in front gives
+those bones a character unlike other genera, so that
+Cycnorhamphus ranks as a good genus, easily distinguished
+from Cuvier's type, in which the four bones
+of the wing are more equal in length, and the last is
+more than half the length of the first; while the
+metacarpus in that genus is only a little longer than
+the humerus, and much shorter than the ulna. The
+<i>Pterodactylus suevicus</i> has the neck vertebr&aelig; flat on
+the under side, and relatively short as compared
+with the more slender and narrower vertebr&aelig; of
+<i>P. Fraasii</i>.</p>
+
+<div class="figcenter" style="width: 599px;">
+<a name="Fig_62" id="Fig_62"></a>
+<span class="caption">FIG. 62. &nbsp;  <i>CYCNORHAMPHUS SUEVICUS</i></span>
+<p class="center">Skeleton restored from the bones in Fig. 60</p>
+<img src="images/i_201.jpg" width="599" height="480" alt="FIG. 62." title="FIG. 62." />
+</div>
+
+<div class="figcenter" style="width: 768px;">
+<a name="Fig_63" id="Fig_63"></a>
+<span class="caption">FIG. 63. &nbsp; RESTORATION OF SKELETON CYCNORHAMPHUS FRAASI<br /><br />
+SHOWING THE LIMBS ON THE RIGHT SIDE</span>
+<p class="center"><i>From a specimen in the Museum at Stuttgart</i></p>
+<img src="images/i_202.jpg" width="768" height="911" alt="FIG. 63." title="FIG. 63." />
+</div>
+
+
+
+<p><span class='pagenum'><a name="Page_171" id="Page_171">[Pg 171]</a></span></p>
+<div class="figcenter" style="width: 768px;">
+<a name="Fig_64" id="Fig_64"></a>
+<span class="caption">FIG. 64. &nbsp; CYCNORHAMPHUS FRAASI<br /><br />
+RESTORATION OF THE FORM OF THE BODY</span>
+<img src="images/i_204.jpg" width="768" height="894" alt="FIG. 64." title="FIG. 64." />
+</div>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_172" id="Page_172">[Pg 172]</a></span></p>
+<h2><a name="CHAPTER_XV" id="CHAPTER_XV"></a><small>CHAPTER XV</small><br /><br />
+
+ORNITHOSAURS FROM THE UPPER
+SECONDARY ROCKS</h2>
+
+
+<p>When staying at Swanage, in Dorsetshire, many
+years ago, I had the rare good fortune to obtain
+from the Purbeck Beds the jaw of a Pterodactyle,
+which had much in common in plan with the <i>Cycnorhamphus
+Fraasii</i> from the Lithographic Slate, which
+is preserved at Stuttgart. The tooth-bearing part of
+this lower jaw is 8 inches long as preserved, extending
+back 3 inches beyond the symphysis portion in which
+the two sides are blended together. It is different
+from Professor Fraas's specimen in having the teeth
+carried much further back, and in the animal being
+nearly twice as large. This fragment of the jaw is
+little more than 1 foot long, which is probably less
+than half its original length. A vertebra nearly
+5 inches long, which is more than twice the length
+of the longest neck bones in the Stuttgart fossil, is
+the only indication of the vertebral column. Professor
+Owen described a wing finger bone from these
+Purbeck Beds, which is nearly 1 foot long. He terms
+it the second of the finger. It may be the third, and
+on the hypothesis that the animal had the proportions
+of the Solenhofen fossil just referred to, the first wing
+<span class='pagenum'><a name="Page_173" id="Page_173">[Pg 173]</a></span>
+finger bone of the English Purbeck Pterodactyle
+would have exceeded 2 feet in length, and would
+give a length for the wing finger of about 5 feet
+3 inches. For this animal the name Doratorhynchus
+was suggested, but at present I am unable to distinguish
+it satisfactorily from Cycnorhamphus, which
+it resembles in the forms both of the neck bones and
+of the jaw. Very small Pterodactyles are also found
+in the English Purbeck strata, but the remains are
+few, and scattered, like these larger bones.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_65" id="Fig_65"></a>
+<span class="caption">FIG. 65. &nbsp; THE LONGEST KNOWN NECK VERTEBRA</span>
+<p class="center">From the Purbeck Beds of Swanage. (Half natural size)</p>
+<img src="images/i_208a.jpg" width="640" height="174" alt="FIG. 65." title="FIG. 65." />
+</div>
+
+
+
+
+<h4>ORNITHODESMUS LATIDENS</h4>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_66" id="Fig_66"></a>
+<span class="caption">FIG. 66. &nbsp;  CERVICAL VERTEBRA OF ORNITHODESMUS</span>
+<p class="center">From the Wealden Beds of the Isle of Wight</p>
+<img src="images/i_208b.jpg" width="640" height="418" alt="FIG. 66." title="FIG. 66." />
+</div>
+
+
+
+<p>The Wealden strata being shallow, fresh-water
+deposits might have been expected to supply better
+knowledge of Pterodactyles than has hitherto been
+<span class='pagenum'><a name="Page_174" id="Page_174">[Pg 174]</a></span>
+available. Jaws of Ornithocheirus sagittirostris have
+been found in the beds at Hastings, and in other
+parts of Sussex. Some fragments are as large as
+anything known. The best-preserved remains have
+come from the Isle of Wight, and were rewards to
+the enthusiastic search of the Rev. W. Fox, of Brixton.
+In the principal specimen the teeth were short and
+wide, the head large and deep with large vacuities,
+but the small brain case of that skull is bird-like.
+The neck bones are 2&frac12; inches long. In the upper
+part of the back the bones are united together by
+anchylosis, so that they form a structure in the back
+like a sacrum, which does not give attachment to the
+scapula, as in some Pterodactyles from the Chalk, but
+the bones are simply blended, as in the frigate-bird,
+allied to Pelicans and Cormorants. And then after a
+few free vertebr&aelig; in the lower part of the back, succeeds
+the long sacrum, formed in the usual way, of many
+vertebr&aelig;. I described a sacrum of this type from the
+Wealden Beds, under the name <i>Ornithodesmus</i>, referable
+to another species, which in many respects was
+so like the sacrum of a Bird that I could not at the
+time separate it from the bird type. This genus has
+a sternum with a strong deep keel, and the articulation
+for the coracoid bones placed at the back of the
+keel in the usual way, but with a relation to each
+other seen in no genus hitherto known, for the
+articular surfaces are wedge-shaped instead of being
+ovate; and instead of being side by side, they obliquely
+overlap, practically as in wading birds like the
+Heron. I have never seen any Pterodactyle teeth so
+flattened and shaped like the end of a lancet; and
+from this character the form was known between
+Mr. Fox and his friends as "latidens." The name<span class='pagenum'><a name="Page_175" id="Page_175">[Pg 175]</a></span>
+Ornithodesmus is as descriptive of the sternum as of
+the vertebral column. The wing bones, as far as
+they are preserved, have the relatively great strength
+in the fore limb which is found in many of the Pterodactyles
+of the Cretaceous period, and are quite as
+large as the largest from the Cambridge Greensand.
+In the Sussex species named <i>P. sagittirostris</i> the
+lower jaw articulation was inches wide.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_67" id="Fig_67"></a>
+<span class="caption">FIG. 67. &nbsp;  STERNUM OF <i>ORNITHODESMUS</i></span>
+<p class="center">Showing the overlapping facets for the coracoid bones (shaded)
+behind the median keel</p>
+<img src="images/i_210a.jpg" width="640" height="377" alt="FIG. 67." title="FIG. 67." />
+</div>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_68" id="Fig_68"></a>
+<span class="caption">FIG. 68. &nbsp; FRONT OF THE KEEL OF THE STERNUM OF
+<i>ORNITHODESMUS LATIDENS</i></span>
+<p class="center">Showing also the articulation for the coracoid bone</p>
+<img src="images/i_210b.jpg" width="640" height="416" alt="FIG. 68." title="FIG. 68." />
+</div>
+
+<p>A few Pterodactyles' bones have been discovered
+<span class='pagenum'><a name="Page_176" id="Page_176">[Pg 176]</a></span>
+in the Neocomian sands of England and Germany,
+and other larger bones occur in the Gault of Folkestone
+and the north of France; but never in such
+association as to throw light on the aspect of the
+skeleton.</p>
+
+
+<h4>ORNITHOCHEIRUS</h4>
+
+<p>Within my own memory Pterodactyle remains
+were equally rare from the Cambridge Greensand.
+The late Professor Owen in one of his public lectures
+produced the first few fragments received from
+Cambridge, and with a knowledge which in its
+scientific method seemed to border on the power of
+creation, produced again the missing parts, so that
+the bones told their story, which the work of waves
+and mineral changes in the rock had partly obliterated.
+Subsequently good fortune gave me the
+opportunity during ten years to help my University
+in the acquisition and arrangement of the finest
+collection of remains of these animals in Europe.
+Out of an area of a few acres, during a year or two,
+came the thousand bones of Ornithosaurs, mostly
+associated sets of remains, each a part of a separate
+skeleton, described in my published catalogues, as
+well as the best of those at York and in the British
+Museum and other collections in London.</p>
+
+<p>The deposit which yields them, named Cambridge
+Greensand, may or may not represent a long period
+of time in its single foot of thickness; but the abundance
+of fossils, obtained whenever the workmen were
+adequately remunerated for preserving them, would
+suggest that the Pterodactyles might have lived
+like sea-birds or in colonies like the Penguins, if
+it were not that the number of examples of each
+species found is always small, and the many variations<span class='pagenum'><a name="Page_177" id="Page_177">[Pg 177]</a></span>
+of structure suggested rather that the individuals
+represent the life of many lands. The collections of
+remains are mostly from villages in the immediate
+vicinity of Cambridge, such as Chesterton, Huntingdon
+Road, Coldham Common, Haslingfield, Barton,
+Shillington, Ditton, Granchester, Harston, Barrington,
+stretching south to Ashwell in Bedfordshire on
+the one hand, as well as further north by Horningsea
+into the fens. Each appears to be the associated
+bones of a single individual. The remains mostly
+belong to comparatively large animals. Some were
+small, though none have been found so diminutive
+as the smallest from the Solenhofen Slate. The
+largest specimens with long jaws appear to have
+had the head measuring not more than eighteen
+inches in length, which is less than half the size of
+the great toothless Pterodactyles from Kansas.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_69" id="Fig_69"></a>
+<span class="caption">FIG. 69. &nbsp; RESTORATION OF THE SKULL OF ORNITHOCHEIRUS</span>
+<img src="images/i_212.jpg" width="640" height="221" alt="FIG. 69." title="FIG. 69." />
+<p class="center">The parts left white are in the Geological Museum at Cambridge. The shaded
+parts have not been found. The two holes are the eye and the nostril<br />
+(From the Cambridge Greensand)</p>
+</div>
+
+<p>The Cambridge specimens manifestly belong to at
+least three genera. Something may be said of the
+characters of the large animals which are included in
+the genus Ornithocheirus. These fossils have many
+points of structure in common with the great
+American toothless forms which are of similar geological
+age. The skull is remarkable for having the<span class='pagenum'><a name="Page_178" id="Page_178">[Pg 178]</a></span>
+back of the head prolonged in a compressed median
+crest, which rose above the brain case, and extended
+upward and over the neck vertebr&aelig;, so as to indicate
+a muscular power not otherwise shown in the group.
+For about three inches behind the brain this wedge
+of bone rested on the vertebr&aelig;, and probably overlapped
+the first three neural arches in the neck.</p>
+
+<p>Another feature of some interest is the expansion
+of the bone which comes below the eye. In Birds
+this malar or cheek bone is a slender rod, but in
+these Pterodactyles it is a vertical plate, which is
+blended with the bone named the quadrate bone,
+which makes the articulation with the lower jaw in
+all oviparous animals.</p>
+
+<p>The beak varies greatly in length and in form,
+though it is never quite so pointed as in the American
+genus, for there is always a little truncation in front,
+when teeth are seen projecting forward from a position
+somewhat above the palate; the snout is often
+massive and sometimes club-shaped. Except for these
+variations of shape in the compressed snout, which is
+characterised by a ridge in the middle of the palate,
+and a corresponding groove in the lower jaw, and
+the teeth, there is little to distinguish what is known
+of the skull in its largest English Greensand fossils
+from the skull remains which abound in the Chalk
+of Kansas.</p>
+
+<p>This English genus Ornithocheirus, represented by
+a great number of species, had the neural arch of
+the neck bones expanded transversely over the body
+of the vertebra in a way that characterises many
+birds with powerful necks, and is seen in a few
+Pterodactyles from Solenhofen.</p>
+
+<p>It is difficult to resist the conclusion that the neck<span class='pagenum'><a name="Page_179" id="Page_179">[Pg 179]</a></span>
+vertebr&aelig; were not usually more than twice to three
+times as long as those of the back, and it would
+appear that the caudal vertebr&aelig; in the English
+Cretaceous types were comparatively large, and
+about twice as long as the dorsal vertebr&aelig;. Unless
+there has been a singular succession of accidents in
+the association of these vertebr&aelig; with the other remains,
+Ornithocheirus had a tail of moderate length,
+formed of a few vertebr&aelig; as long as those of the
+neck, though more slender, quite unlike the tail in
+either the long-tailed or short-tailed groups of Solenhofen
+Pterodactyles, and longer than in the toothless
+Pterodactyles of America.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_70" id="Fig_70"></a>
+<span class="caption">FIG. 70. &nbsp; CERVICAL VERTEBRA, ORNITHOCHEIRUS</span>
+<p class="center">Under side, half natural size. (Cambridge Greensand)</p>
+<img src="images/i_214.jpg" width="640" height="370" alt="FIG. 70." title="FIG. 70." />
+</div>
+
+<p>The singular articulation for the humerus at the
+truncated extremity of the coracoid bone is a
+character of this group, as is the articulation of the
+scapul&aelig; with the neural arches of the dorsal vertebr&aelig;,
+at right angles to them (<a href="#Page_115">p. 115</a>), instead of running
+over the ribs as in Birds and as in other Pterodactyles.</p>
+
+<p>The smaller Pterodactyles have their jaws less compressed
+from side to side. The upper arm bone, the
+humerus, instead of being truncated at its lower end
+as in Ornithocheirus, is divided into two or three<span class='pagenum'><a name="Page_180" id="Page_180">[Pg 180]</a></span>
+rounded articular surfaces. That for the radius, the
+bone which carries the wrist, is a distinct and oblique
+rounded facet, while the ulna has a rounded and
+pulley-like articulation on which the hand may rotate.
+These differences are probably associated with an
+absence of the remarkable mode of union of the
+scapul&aelig; with the dorsal vertebr&aelig;. But I have
+hesitated to give different names to these smaller
+genera because no example of scapula has come
+under my notice which is not truncated at the free
+end. I do not think this European type can be
+the Nyctodactylus of Professor Marsh, in which
+sutures appear to be persistent between the bodies
+of the vertebr&aelig; and their arches, because no examples
+have been found at Cambridge with the neural arches
+separated, although the scapula is frequently separated
+from the coracoid in large animals.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_71" id="Fig_71"></a>
+<span class="caption">FIG. 71. &nbsp;  UPPER AND LOWER JAWS OF AN ENGLISH PTERODACTYLE
+FROM THE CHALK, AS PRESERVED</span>
+<img src="images/i_215.jpg" width="640" height="301" alt="FIG. 71." title="FIG. 71." />
+</div>
+
+
+<div class="figcenter" style="width: 618px;">
+<a name="Fig_72" id="Fig_72"></a>
+<span class="caption">FIG. 72. &nbsp;  THE PALATE OF THE ENGLISH TOOTHLESS
+PTERODACTYLE, ORNITHOSTOMA</span>
+<img src="images/i_216.jpg" width="618" height="480" alt="FIG. 72." title="FIG. 72." />
+</div>
+
+
+<div class="figcenter" style="width: 480px;">
+<a name="Fig_73" id="Fig_73"></a>
+<span class="caption">FIG. 73. &nbsp;  TYPES OF THE AMERICAN TOOTHLESS
+PTERODACTYLE, ORNITHOSTOMA</span>
+<p class="center">Named by Marsh, Pteranodon</p>
+<img src="images/i_217.jpg" width="480" height="489" alt="FIG. 73." title="FIG. 73." />
+</div>
+
+
+
+
+<h4>ORNITHOSTOMA</h4>
+
+<p>The most interesting of all the English Pterodactyle
+remains is the small fragment of jaw figured by
+Sir Richard Owen in 1859, which is a little more than
+<span class='pagenum'><a name="Page_181" id="Page_181">[Pg 181]</a></span>
+two inches long and an inch wide, distinguished by a
+concave palate with smooth rounded margins to the
+jaws and a rounded ridge to the beak. It is the only
+satisfactory fragment of the animal which has been
+figured, and indicates a genus of toothless Pterodactyles,
+for which the name Ornithostoma was first used
+in 1871. After some years Professor Marsh found
+toothless Pterodactyles in Kansas, and indicated
+several species. There are remains to the number of
+six hundred specimens of these American animals in
+the Yale Museum alone; but very little was known of
+them till Professor Williston, of Lawrence, in Kansas,
+described the specimens from the Kansas University
+Museum, when it became evident that the bones of
+the skeleton are mostly formed on the same plan
+as those of the Cambridge Greensand genus, Ornithocheirus.
+They are not quite identical. Professor
+Williston adopts for them the name Ornithostoma,
+in preference to Pteranodon which Marsh had
+<span class='pagenum'><a name="Page_182" id="Page_182">[Pg 182]</a></span>
+suggested. Both animals have the dagger-shaped form
+of jaw, with corresponding height and breadth of the
+palate. The same flattened sides to the snout, converging
+upwards to a rounded ridge, the same compressed
+rounded margin to the jaw, which represents
+the border in which teeth are usually implanted, and
+in both the palate has the same smooth character
+forming a single wide concave channel. Years previously
+I had the pleasure of showing to Professor
+Marsh the remarkable characters of the jaw, shoulder-girdle
+bones, and scapul&aelig; in the Greensand Pterodactyles
+while the American fossils were still undiscovered.
+I subsequently made the restoration of the
+shoulder-girdle (<a href="#Page_115">p. 115</a>). Professor Williston states to
+<span class='pagenum'><a name="Page_183" id="Page_183">[Pg 183]</a></span>
+me that the shoulder-girdle bones in American examples
+of Ornithostoma have a close resemblance to
+those of Ornithocheirus figured in 1891, as is evident
+from remains now shown in the British Museum. It
+appears that the Kansas bones are almost invariably
+crushed flat, so that their articular ends are distorted.
+The neck vertebr&aelig; are relatively stout as in Ornithocheirus.
+The hip-girdle of the American Ornithostoma
+can be closely paralleled in some English
+specimens of Ornithocheirus, though each prepubic
+bone is triangular in the American fossils as in
+<i>P. rhamphastinus</i>. They are united into a transverse
+bar as in Rhamphorhynchus, unknown in the English
+fossils. The femur has the same shape as in Ornithocheirus;
+and the long tibia terminates in a pulley.
+There is no fibula. The sternum in both has a
+manubrium, or thick keel mass, prolonged in front
+of its articular facets for the coracoid bones, which
+are well separated from each other. Four ribs
+articulate with its straight sides. The animal has
+four toes and the fifth is rudimentary; there are no
+claws to the first and second.</p>
+
+<div class="figcenter" style="width: 800px;">
+<a name="Fig_74" id="Fig_74"></a>
+<span class="caption">FIG. 74. &nbsp;  RESTORATION OF THE SKELETON OF
+<i>ORNITHOSTOMA INGENS</i> (<span class="smcap">Marsh</span>)</span>
+<img src="images/i_218.jpg" width="800" height="311" alt="FIG. 74." title="FIG. 74." />
+<p class="center">From the Niobrara Cretaceous of Western Kansas. Made by Professor Williston.
+The original has a spread of wing of about 19 feet 4 inches. Fragments of
+larger individuals are preserved at Munich</p>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_184" id="Page_184">[Pg 184]</a></span>In
+the restoration which Professor Williston has
+made the wing metacarpal is long, and in the shortest
+specimen measures 1 foot 7 inches, and in the longest
+1 foot 8 inches. This is exactly equal to the length
+of the first phalange of the wing finger. The second
+wing finger bone is 3 inches shorter, the third is little
+more than half the length of the first, while the fourth
+is only 6&frac34; inches long, showing a rapid shortening of
+the bones, a condition which may have characterised
+all the Cretaceous Pterodactyles. The short
+humerus, about 1 foot long, and the fore-arm, which
+is scarcely longer, are also characteristic proportions
+of Ornithostoma or Pteranodon, as known from the
+American specimens. Professor Williston gives no
+details of the remarkable tail, beyond saying that the
+tail is small and short, and that the vertebr&aelig; are flat
+at the ends, without transverse processes. In the restoration
+the tail is shorter than in the short-tailed
+species from the Lithographic Slate, and unlike the
+tail in Ornithocheirus.</p>
+
+<p>&nbsp;</p>
+
+<p>This is the succession of Pterodactyles in geological
+time. Their history is like that of the human
+race. In the most ancient nations man's life comes
+upon us already fully organised. The Pterodactyles
+begin, so far as isolated bones are concerned, in the
+Rh&aelig;tic strata; perhaps in the Muschelkalk or middle
+division of the Trias. And from the beginning
+of the Secondary time they live on with but little
+diversity in important and characteristic structures,
+and so far as habit goes, the great Pterodactyles
+of the Upper Chalk of England cannot be said to
+be more highly organised than the earlier stiff-tailed
+genera of the Lias or the Oolites. There is nothing<span class='pagenum'><a name="Page_185" id="Page_185">[Pg 185]</a></span>
+like evolution. No modification such as that which
+derives the one-toed horse or the two-toed ox from
+ancestors with a larger number of digits. On the
+other hand, there is little, if any, evidence of degeneration.
+The later Pterodactyles do not appear
+to have lost much, although the tail in some of the
+Solenhofen genera may be degenerate when compared
+with the long tail of Dimorphodon; but the
+short-tailed types are found side by side with the
+long-tailed Rhamphorhynchus. The absence of teeth
+may be regarded as degeneration, for they have
+presumably become lost, in the same way that Birds
+now existing have lost the teeth which characterised
+the fossil birds&mdash;Ichthyornis of the American Greensand,
+and Arch&aelig;opteryx of the Upper Oolites of
+Bavaria. But just as some of the earlier Pterodactyles
+have no teeth at the extremity of the jaw, such
+as Dorygnathus and Rhamphorhynchus, so the loss
+of teeth may have extended backward till the jaws
+became toothless. The specimens hitherto known
+give no evidence of such a change being in progress.
+But just as the division of Mammals termed Edentata
+usually wants only the teeth which characterise the
+front of the jaw, yet others, like the Great Ant-eater
+of South America named Myrmecophaga, have the
+jaws as free from teeth as the toothless Pterodactyles
+or living Birds, and show that in that order the teeth
+have no value in separating these animals into subordinate
+groups any more than they have among the
+Monotremata, where one type has teeth and the other
+is toothless.<span class='pagenum'><a name="Page_186" id="Page_186">[Pg 186]</a></span></p>
+
+<p>The following table gives a summary of the Geological
+History and succession in the Secondary
+Rocks of the principal genera of Flying Reptiles.</p>
+
+
+<div class='center'>
+<table border="1" cellpadding="4" cellspacing="0" summary="">
+<tr><th rowspan='2'>GEOLOGICAL FORMATIONS.</th><th colspan='2'>NAMES OF THE GENERA.</th></tr>
+<tr><th>British and European.</th><th>North American.</th></tr>
+<tr>
+  <td align='left'>Upper Chalk<br /><br />Lower Chalk<br />Upper Greensand<br />Gault</td>
+  <td align='left'><br /><br />} Ornithocheirus<br />}  &nbsp; &nbsp; &nbsp; &nbsp; Ornithostoma</td>
+  <td align='left'>} Ornithostoma<br />} &nbsp; &nbsp; &nbsp; &nbsp;(<i>Pteranodon</i>)<br />} Nyctodactylus<br /><br />&nbsp;</td>
+</tr>
+<tr>
+  <td align='left'>Lower Greensand<br />Wealden<br />Purbeck</td>
+  <td align='left'>Ornithodesmus<br />Doratorhynchus</td>
+  <td align='left'></td>
+</tr>
+<tr>
+  <td align='left'>Portland<br />Kimeridge Clay and Solenhofen Slate<br />Coralline Oolite<br />Oxford Clay</td>
+  <td align='left'>{ Pterodactylus<br />{ Ptenodracon<br />{ Cycnorhamphus<br />{ Diopecephalus<br />{ Rhamphorhynchus<br />{ Scaphognathus</td>
+  <td>&nbsp;</td>
+</tr>
+<tr>
+  <td align='left'>Great Oolite and Stonesfield Slate<br />Inferior Oolite</td>
+  <td align='left'>Rhamphocephalus</td>
+  <td>&nbsp;</td>
+</tr>
+<tr>
+  <td align='left'>Upper Lias<br /><br />Lower Lias</td>
+  <td align='left'>{ Campylognathus<br />{ Dorygnathus<br />Dimorphodon</td>
+  <td align='left'>&nbsp;</td>
+</tr>
+<tr>
+  <td align='left'>Rh&aelig;tic<br /><br />Muschelkalk</td>
+  <td align='left'>bones<br /><br />? bones</td>
+  <td align='left'>&nbsp;</td>
+</tr>
+</table></div>
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_187" id="Page_187">[Pg 187]</a></span></p>
+<h2><a name="CHAPTER_XVI" id="CHAPTER_XVI"></a><small>CHAPTER XVI</small><br /><br />
+
+CLASSIFICATION OF THE
+ORNITHOSAURIA</h2>
+
+
+<p>When an attempt is made to determine the
+place in nature of an extinct group of animals
+and the relation to each other of the different types
+included within its limits, so as to express those facts
+in a classification, attention is directed in the first
+place to characters which are constant, and persist
+through the whole of its constituent genera. We
+endeavour to find the structural parts of the skeleton
+which are not affected by variation in the dentition,
+or the proportions of the extremities, or length of
+the tail, which may define families or genera, or
+species.</p>
+
+<p>It has already been shown that while in many
+ways the Ornithosaurian animals are like Birds, they
+have also important resemblances to Reptiles. They
+are often named Pterosauria. The wing finger gives
+a distinctive character which is found in neither one
+class of existing animals nor the other, and is common
+to all the Pterodactyles at present known. They have
+been named Ornithosauria as a distinct minor division
+of back-boned animals, which may be regarded as
+neither Reptiles nor Birds in the sense in which those<span class='pagenum'><a name="Page_188" id="Page_188">[Pg 188]</a></span>
+terms are used to define a Lizard or Ostrich among
+animals which still exist. It is not so much that they
+mark a transition from Reptile to Bird, as that they
+are a group which is parallel to Birds, and more
+manifestly holds an intermediate place than Birds do
+between Reptiles and Mammals. In plan of structure
+Bird and Reptile have more in common than was
+at one time suspected. The late Professor Huxley
+went so far as to generalise on those coincidences
+in parts of the skeleton, and united Birds and Reptiles
+into one group, which he named Sauropsida, to express
+the coincidences of structure between the Lizard
+and the Bird tribes. The idea is of more value than
+the term in which it is expressed, because Reptiles
+are not, as we have seen, a group of animals which
+can be defined by any set of characters as comprehensive
+as those which express the distinctive features
+of Birds. From the anatomist's point of view Birds
+are a smaller group, and while some Reptiles have
+affinity with them, it is rather the extinct than the
+living groups which indicate that relation. Other
+Reptiles have affinities of a more marked kind with
+Mammals, and there are points in the Ornithosaurian
+skeleton which are distinctly Mammalian. So that
+when the Monotreme Mammals are united with
+South African reptiles known as Theriodontia, which
+resemble them, in a group termed Theropsida to
+express their mammalian resemblances, it is evident
+that there is no one continuous chain of life or gradation
+in complexity of structure of animals.</p>
+
+<p>We have to determine whether the Ornithosauria incline
+towards the Sauropsidan or Bird-Reptile alliance,
+or to the Mammal-Reptile or Theropsidan alliance.
+There can be no doubt that the predominant ten<span class='pagenum'><a name="Page_189" id="Page_189">[Pg 189]</a></span>dency
+is to the former, with a minor affinity towards
+the latter.</p>
+
+<p>The Ornithosauria are one of a series of groups
+of animals, living and extinct, which have been
+combined in an alliance named the Ornithomorpha.
+That group includes at least five great divisions
+of animals, which circle about birds, known as
+Ornithosauria, Crocodilia, Saurischia, Aves, Ornithischia,
+and Aristosuchia. Their relations to each other
+are not evident in an enumeration, but may be shown
+in some degree in a diagram (see <a href="#Page_190">p. 190</a>).</p>
+
+
+<h4>THE ORNITHOMORPHA</h4>
+
+<p>The Ornithomorpha arranged in this way show
+that the three middle groups&mdash;carnivorous Saurischia,
+Aristosuchia, herbivorous Ornithischia&mdash;which are
+usually united as Dinosauria, intervene between
+Birds and Ornithosaurs; and that the Crocodilia
+and Ornithosauria are parallel groups which are connected
+with Birds, by the group of Dinosaurs, which
+resembles Birds most closely.</p>
+
+<p>The Ornithomorpha is only one of a series of large
+natural groups of animals into which living and
+extinct terrestrial vertebrata may be arranged. And
+the succeeding diagram may contribute to make
+evident the relations of Ornithosauria to the other
+terrestrial vertebrata (see <a href="#Page_191">p. 191</a>).</p>
+
+<p>Herein it is seen that while the Ornithomorpha
+approach towards Mammalia through the Ornithosauria,
+and less distinctly through the Crocodilia,
+they approach more directly to the Sauromorpha,
+through the Plesiosaurs and Hatteria; while
+that group also approaches more directly to the
+Mammals through the Plesiosaurs and Anomodonts.</p>
+<p><span class='pagenum'><a name="Page_190" id="Page_190">[Pg 190]</a></span></p>
+
+<h3><span class="smcap">Diagram of the Affinities of the Orders of Animals
+comprised in the Ornithomorpha.</span></h3>
+
+<div class="figcenter" style="width: 600px;">
+<img src="images/i_225.jpg" width="600" height="644" alt="" title="" />
+<span class="caption">After a diagram in the <i>Philosophical Transactions of the
+Royal Society</i>, 1892.</span>
+</div>
+
+<p>The Aristosuchia is imperfectly known, and therefore
+to some extent a provisional group. It is a
+small group of animals.</p>
+<p><span class='pagenum'><a name="Page_191" id="Page_191">[Pg 191]</a></span></p>
+
+<h3><span class="smcap">Diagram showing the Relations of the Ornithomorpha
+to the chief large groups of Terrestrial Vertebrata,<br />
+and their affinities with each other.</span></h3>
+
+<div class="figcenter" style="width: 499px;">
+<img src="images/i_226.jpg" width="499" height="480" alt="" title="" />
+<span class="caption">After a diagram in the <i>Philosophical Transactions of the
+Royal Society</i>, 1892.</span>
+</div>
+
+
+
+<p>Cordylomorpha are Ichthyosaurs and the Labyrinthodont
+group. Herpetomorpha include Lacertilia,
+Hom&#339;osauria, Dolichosauria, Chameleonoidea,
+Ophidia, Pythonomorpha.</p>
+
+<p><span class='pagenum'><a name="Page_192" id="Page_192">[Pg 192]</a></span></p>
+<p>The Sauromorpha comprises the groups of extinct
+and living Reptiles named Chelonia, Rhynchocephala,
+Sauropterygia, Anomodontia, Nothosauria, and Protorosauria.
+These details may help to explain the
+place which has been given to the Ornithosauria in
+the classification of animals.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_75" id="Fig_75"></a>
+<span class="caption">FIG. 75. &nbsp;  COMPARISON OF SIX GENERA</span>
+<p class="center">The skulls are seen on the left side in the order of the names below them</p>
+<img src="images/i_227.jpg" width="640" height="458" alt="FIG. 75." title="FIG. 75." />
+</div>
+
+
+
+<p>Turning to the Pterodactyles themselves, Von
+Meyer divided them naturally into short-tailed and
+long-tailed. The short-tailed indicated by the name
+Pterodactylus he further divided into long-nosed and
+short-nosed. The short-nosed genus has since been
+named Ptenodracon (<a href="#Fig_59">Fig. 59, p. 167</a>). The long-tailed
+group was divided into two types&mdash;the Rhamphorhynchus
+of the Solenhofen Slate (<a href="#Fig_56">Fig. 56, p. 161</a>)
+and the English form now known as Dimorphodon
+(<a href="#Fig_52">Fig. 52, p. 150</a>), which had been described from the
+Lias.</p>
+
+<p>The Cretaceous Pterodactyles form a distinct<span class='pagenum'><a name="Page_193" id="Page_193">[Pg 193]</a></span>
+family. So that, believing the tail to have been short
+in that group (<a href="#Fig_58">Fig. 58</a>), there are two long-tailed as
+well as two short-tailed families, which were defined
+from their typical genera Pterodactylus, Ornithocheirus,
+Rhamphorhynchus, and Dimorphodon.</p>
+
+<p>The differences in structure which these animals
+present are, first: the big-headed forms from the Lias
+like Dimorphodon, agree with the Rhamphorhynchus
+type from Solenhofen in having a vacuity in the skull
+defined by bone, placed between the orbit of the eye
+and the nostril. With those characters are correlated
+the comparatively short bones which correspond to
+the back of the hand termed metacarpals, and the
+tail is long, and stiffened down its length with ossified
+tendons. These characters separate Ornithosaurs
+with long tails from those with short tails.</p>
+
+<p>The short-tailed types represented by Pterodactylus
+and Ornithocheirus have no distinct antorbital vacuity
+in the skull defined by bone. The metacarpal bones
+of the middle hand are exceptionally elongated, and
+the tail, which was flexible in both, appears to have
+been short. These differences in the skeleton warrant
+a primary division of flying reptiles into two principal
+groups.</p>
+
+<p>The short-tailed group, which was recognised by
+De Blainville as intermediate between Birds and
+Reptiles, may take the name Pterodactylia, which
+he suggested as a convenient, distinctive name. It
+may probably be inconvenient to enlarge its significance
+to comprise not only the true Pterodactyles
+originally defined as Pterosauria, but the newer
+Ornithostoma and Ornithocheirus which have been
+grouped as Ornithocheiroidea.</p>
+
+<p>The second order, in which the wing membrane<span class='pagenum'><a name="Page_194" id="Page_194">[Pg 194]</a></span>
+appears to have had a much greater extent, in being
+carried down the hind limbs, where the outermost
+digit and metatarsal are modified for its support, has
+been named Pterodermata, to include the types
+which are arranged around Rhamphorhynchus and
+Dimorphodon.</p>
+
+<p>Both these principal groups admit of subdivision
+by many characters in the skeleton, the most remarkable
+of which is afforded by the pair of bones carried
+in front of the pubes, and termed prepubic bones.
+In the Pterodactyle family the bones in front of the
+pubes are always separate from each other, always
+directed forward, and have a peculiar fan-shaped
+form with concave sides like the bone which holds a
+similar position in a Crocodile. In the Ornithocheirus
+family the prepubic bones appear to have been originally
+triangular, but were afterwards united so as
+to form a strong continuous bar which extends transversely
+across the abdomen in advance of the pubic
+bones. This at least is the distinctive character in the
+genus Ornithostoma according to Professor Williston,
+which in many ways closely resembles Ornithocheirus.</p>
+
+<p>The two families in the long-tailed order named
+Pterodermata are separated from each other by a
+similar difference in their prepubic bones. In Dimorphodon
+those bones are separate from each other,
+and remain distinct through life, meeting in the
+middle line of the body in a wide plate. On the
+other hand, in Rhamphorhynchus the prepubic bones,
+which are at first triangular and always slender,
+become blended together into a slight transverse bar,
+which only differs from that attributed to Ornithostoma
+in its more slender bow-shaped form.</p>
+
+
+
+<p>Thus if other characters of the skeleton are
+<span class='pagenum'><a name="Page_195" id="Page_195">[Pg 195]</a></span>
+ignored and a classification based upon the structure of
+the pelvis and prepubic bones, there would be some
+ground for associating the long-tailed Rhamphorhynchus
+from the Upper Oolites which is losing the
+teeth in the front of its jaw with the Cretaceous Ornithostoma,
+which has the teeth completely wanting;
+while the long-tailed Dimorphodon would come into
+closer association with the short-tailed Pterodactylus.
+The drum-stick bone or tibia in Dimorphodon, with
+its slender fibula, like that of a Bird, also resembles
+a Bird in the rounded and pulley-shaped terminal
+end which makes the joint corresponding to the
+middle of the ankle bones in man. The same condition
+of a terminal pulley joint is found in the
+Cretaceous Pterodactyles. But in the true Pterodactyles
+and in Rhamphorhynchus there usually is
+no pulley-shaped termination to the lower end of
+the drum-stick, for the tarsal bones remain separate
+from each other, and form two rows of ossifications,
+showing the same differences as separate Dinosaurs
+into the divisions which have been referred to, from
+their Bird-like pelvis and tibio-tarsus, as Ornithischia
+in the one case, and Saurischia in the other from
+their bones being more like those of living Lizards.</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_76" id="Fig_76"></a>
+<span class="caption">FIG. 76. &nbsp;  LEFT SIDE OF PELVIS OF ORNITHOSTOMA</span>
+<p class="center">(After Williston)</p>
+<img src="images/i_230.jpg" width="640" height="296" alt="FIG. 76." title="FIG. 76." />
+</div>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_196" id="Page_196">[Pg 196]</a></span></p>
+<h2><a name="CHAPTER_XVII" id="CHAPTER_XVII"></a><small>CHAPTER XVII</small><br /><br />
+
+FAMILY RELATIONS OF PTERODACTYLES
+TO ANIMALS WHICH
+LIVED WITH THEM</h2>
+
+
+<p>Enough has been said of the general structure
+of Pterodactyles and the chief forms which
+they assumed while the Secondary rocks were accumulating,
+to convey a clear idea of their relations
+to the types of vertebrate animals which still survive
+on the earth. We may be unable to explain the
+reasons for their existence, and for their departure
+from the plan of organisation of Reptiles and Birds.
+But the evidence has not been exhausted which may
+elucidate their existence. Sometimes, in problems of
+this kind, which involve comparison of the details of
+the skeleton in different animals, it is convenient to
+imagine the possibility of changes and transitions
+which are not yet supported by the discovery of
+fossil remains. If, for example, the Pterodactyle be
+conceived of as divested of the wing finger, which is
+its most distinctive character, or that finger is supposed
+to be replaced by an ordinary digit, like the three-clawed
+digits of the hand which we have regarded
+as applied to the ground, where, it may be asked,
+would the animal type be found which approximates<span class='pagenum'><a name="Page_197" id="Page_197">[Pg 197]</a></span>
+most closely to a Pterodactyle which had been thus
+modified? There are two possible replies to such a
+question, suggested by the form of the foot. For
+the old Bird Arch&aelig;opteryx has three such clawed
+digits, but no wing finger. And some Dinosaurs also
+have the hand with three digits terminating in claws,
+which are quite comparable to the clawed digits of
+Pterodactyles.</p>
+
+<p>The truth expressed in the saying that no man by
+taking thought can add a cubit to his stature is of
+universal application in the animal world, in relation
+to the result upon the skeleton of the exercise of a
+function by the individual. Yet such is the relation
+in proportions of the different parts of the animal to
+the work which it performs, so marked is the evidence
+that growth has extended in direct relation to use of
+organs and active life, and that structures have become
+dwarfed from overwork, or have wasted away from
+disuse&mdash;seen throughout all vertebrate animals, that
+we may fairly attribute to the wing finger some correlated
+influence upon the proportions of the animal,
+as a consequence of the dependence of the entire
+economy upon each of its parts. Therefore if an
+allied animal did not possess a wing finger, and did
+not fly, it might not have developed the lightness of
+bone, or the length of limb which Pterodactyles
+possess.</p>
+
+<p>The mere expansion of the parachute membrane
+seen in so-called flying animals, both Mammals and
+Reptiles, which are devoid of wings, is absolutely
+without effect in modifying the skeleton. But when
+in the Bat a wing structure is met with which may
+be compared to a gigantic extension of the web foot
+of the so-called Flying Frog, the bones of the fingers<span class='pagenum'><a name="Page_198" id="Page_198">[Pg 198]</a></span>
+and the back of the hand elongate and extend under
+the stimulus of the function of flight in the same
+way as the legs elongate in the more active hoofed
+animals, with the function of running. Therefore it
+is not improbable that the limbs shared to some
+extent in growth under stimulus of exercise which
+developed the wing finger. And if an animal can be
+found among fossils so far allied as to indicate a
+possible representative of the race from which these
+Flying Dragons arose, it might be expected to be at
+least shorter legged, and possibly more distinctly
+Reptilian in the bones of the shoulder-girdle which
+support the muscles used in flight. It may readily
+be understood that the kinds of life which were most
+nearly allied to Pterodactyles are likely to have
+existed upon the earth with them, and that flight was
+only one of the modes of progression which became
+developed in relation to their conditions of existence.
+The principal assemblage of terrestrial animals
+available for such comparison is the Dinosauria. They
+may differ from Pterodactyles as widely as the Insectivora
+among Mammals differ from Bats, but not
+in a more marked way. Comparisons will show that
+there are resemblances between the two extinct groups
+which appeal to both reason and imagination.</p>
+
+<p>Dinosaurs are conveniently divided by characters
+of the pelvis first into the order Saurischia, which
+includes the carnivorous Megalosaurus and the Cetiosaurus,
+with the pelvis on the Reptile plan; and
+secondly the order Ornithischia, represented by Iguanodon,
+with the pelvis on the Bird plan. It may be
+only a coincidence, but nevertheless an interesting
+one, that the characters of those two great groups of
+reptiles, which also extend throughout the Secondary<span class='pagenum'><a name="Page_199" id="Page_199">[Pg 199]</a></span>
+rocks, are to some extent paralleled in parts of the
+skeleton of the two divisions of Pterodactyles. This
+may be illustrated by reference to the skull, pelvis,
+hind limb, and the pneumatic condition of the bones.</p>
+
+<div class="figcenter" style="width: 524px;">
+<a name="Fig_77" id="Fig_77"></a>
+<span class="caption">FIG. 77. &nbsp;  COMPARISON OF THE SKULL OF THE
+DINOSAUR ANCHISAURUS WITH THE ORNITHOSAUR DIMORPHODON</span>
+<img src="images/i_234.jpg" width="524" height="480" alt="FIG. 77." title="FIG. 77." />
+</div>
+
+
+<p>The Saurischian Dinosauria have an antorbital
+vacuity in the side of the skull between the nasal
+opening and the eye, as in the long-tailed Ornithosaurs
+named Pterodermata. In some of the older
+genera of these carnivorous Dinosaurs of the Trias,
+the lateral vacuities of the head are as large as in
+Dimorphodon. But in some at least of the Iguanodont,
+or Ornithischian Dinosaurs, there is no antorbital
+vacuity, and the side of the face in that
+respect resembles the short-tailed Pterodactylia.
+The skull of a carnivorous Dinosaur possesses teeth
+which, though easily distinguished from those of
+Pterodactyles, can be best compared with them. The<span class='pagenum'><a name="Page_200" id="Page_200">[Pg 200]</a></span>
+most striking difference is in the fact that in the
+Dinosaur the nostrils are nearly terminal, while in
+the Pterodactyle they are removed some distance
+backward. This result is brought about by growth
+taking place, in the one case at the front margin of
+the maxillary bone so as to carry the nostril forward,
+and in the other case at the back margin of the premaxillary
+bone. Thus an elongated part of the jaw
+is extended in front of the nostril. Hence there is
+a different proportion between the premaxillary and
+maxillary bones in the two groups of animals, which
+corresponds to the presence of a beak in a bird, and
+its absence in living reptiles. It is not known whether
+the extremity of the Pterodactyle's beak is a single
+bone, the intermaxillary bone, such as forms the
+corresponding toothless part of the jaw in the South
+African reptile Dicynodon, or whether it is made
+by the pair of bones called premaxillaries which
+form the extremity of the jaw in most Dinosaurs.
+Too much importance may perhaps be attached
+to such differences which are partly hypothetical,
+because the extinct Ichthyosaurus, which has an exceptionally
+long snout, has the two premaxillary
+bones elongated so as to extend backward to the
+nostrils. A similar elongation of those bones is seen
+in Porpoises, which also have a long snout; and the
+bones are carried back from the front of the head to
+the nostrils, which are sometimes known as blowholes.
+But the Porpoise has those premaxillary
+bones not so much in advance of the bones which
+carry teeth named maxillary, as placed in the interspace
+between them. The nostrils, however, are not
+limited to the extremity of the head in all Dinosaurs.
+If this region of the beak in Dimorphodon be compared
+<span class='pagenum'><a name="Page_201" id="Page_201">[Pg 201]</a></span>
+with the corresponding part of a Dinosaur
+from the Permian rocks, or Trias, the relation of the
+nostril to the bones forming the beak may be better
+understood.</p>
+
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_78" id="Fig_78"></a>
+<span class="caption">FIG. 78. &nbsp;  COMPARISON OF THE SKULL OF THE
+DINOSAUR ORNITHOSUCHUS WITH THE ORNITHOSAUR DIMORPHODON</span>
+<img src="images/i_236.jpg" width="640" height="470" alt="FIG. 78." title="FIG. 78." />
+</div>
+
+<p>In the sandstone of Elgin, usually named Trias, a
+small Dinosaur is found, which has been named Ornithosuchus,
+from the resemblance of its head to that
+of a Bird. Seen from above, the head has a remarkable
+resemblance to the condition in Rhamphorhynchus,
+in the sharp-pointed beak and positions
+of the orbits and other openings. In side view the
+orbits have the triangular form seen in Dimorphodon,
+and the preorbital vacuities are large, as in that genus,
+while the lateral nostrils, which are smaller, are further
+forward in the Dinosaur. The differences from Dimorphodon
+are in the articulation for the jaw being
+carried a little backward, instead of being vertical as
+in the Pterodactyle, and the bone in front of the
+nose is smaller. Notwithstanding probable differences<span class='pagenum'><a name="Page_202" id="Page_202">[Pg 202]</a></span>
+in the palate, the approximation, which extends to
+the Crocodile-like vacuity in the lower jaw, is such
+that by slight modification in the skull the differences
+would be substantially obliterated by which the skull
+of such an Ornithosaur is technically distinguished
+from such a Dinosaur.</p>
+
+<p>The back of the skull is clearly seen in the Whitby
+Pterodactyle, and its structure is similar to the corresponding
+part of such Dinosaurs as Anchisaurus or
+Atlantosaurus, without the resemblance quite amounting
+to identity, but still far closer than is the resemblance
+between the same region in the heads of
+Crocodiles, Lizards, Serpents, Chelonians. Few of
+these fossil Dinosaur skulls are available for comparison,
+and those differ among themselves. The
+coincidences rather suggest a close collateral relation
+than prove the elaboration of one type from the
+other. They may have had a common ancestor.</p>
+
+<p>The Trias rocks near Stuttgart have yielded Dinosaurs
+as unlike Pterodactyles as could be imagined,
+resembling heavily armoured Crocodiles, in such types
+as the genus Belodon. Its jaws are compressed from
+side to side, as in many Pterodactyles, and the nostrils
+are at least as far backward as in Rhamphorhynchus.
+Belodon has preorbital vacuities and postorbital vacuities,
+but the orbit of the eye is never large, as in
+Pterodactyles. It might not be worth while dwelling
+on such points in the skull if it were not that the
+pelvis in Belodon is a basin formed by the blending
+of the expanded plates of the ischium and the pubis,
+into a sheet of bone which more nearly resembles
+the same region in Pterodactyles than does the
+ischio-pubic region in other Dinosaurian animals
+like Cetiosaurus.<span class='pagenum'><a name="Page_203" id="Page_203">[Pg 203]</a></span></p>
+
+<p>The backbone in a few Dinosaurs is suggestive of
+Pterodactyles. In such genera as have been named
+C&#339;lurus and Calamospondylus, in which the skeleton
+is only partially known, the neck vertebr&aelig; become
+elongated, so as to compare with the long-necked
+Pterodactyles. The cervical rib is often very similar
+to that type, and blended with the vertebra, as in
+Pterodactyles and Birds. The early dorsal vertebr&aelig;
+of Pterodactyles might almost be mistaken for those
+of Dinosaurs. The tail vertebr&aelig; of a Pterodactyle
+are usually longer than in long-tailed Dinosauria.</p>
+
+<p>In the limbs and the bony girdles which support
+them there is more resemblance between Pterodactyles
+and Dinosaurs than might have been anticipated,
+considering their manifest differences in
+habit. Thus all Dinosaurs have the hip bone named
+ilium prolonged in front of the articulation for the
+femur as well as behind it, almost exactly as in
+Pterodactyles and Birds (see <a href="#Page_95">p. 95</a>). There is some
+difference in the pubis and ischium which is more
+conspicuous in form than in direction of the bones.
+There is a Pterodactyle imperfectly preserved, named
+<i>Pterodactylus dubius</i>, in which the ischium is directed
+backward and the pubis downward, and the bones
+unite below the acetabular cavity for the head of the
+femur to work in, but do not appear to be otherwise
+connected. In Rhamphorhynchus the connexion
+between these two thickened bars is made by a thin
+plate of bone. In such a Dinosaur as the American
+carnivorous Ceratosaurus the two bars of the pubis
+and ischium remain separate and diverging, and
+there is no film of bone extending over the interspace
+between them. The development of such a
+bony condition would make a close approximation
+<span class='pagenum'><a name="Page_204" id="Page_204">[Pg 204]</a></span>
+between the Ornithosaurian pelvis and that of those
+Dinosaurs which closely resemble Pterodactyles in
+skull and teeth.</p>
+
+
+<div class="figcenter" style="width: 492px;">
+<a name="Fig_79" id="Fig_79"></a>
+<span class="caption">FIG. 79. &nbsp; LEFT SIDE OF PELVIS</span>
+<img src="images/i_239.jpg" width="492" height="480" alt="FIG. 79." title="FIG. 79." />
+<p class="center">A Pterodactyle is shown between a carnivorous Dinosaur above and
+a herbivorous Dinosaur below</p>
+</div>
+
+
+<p>Another pelvic character of some interest is the
+blending of the pubis and ischium of the right and
+left sides in the middle line of the body. There are
+some genera of Dinosaurs like the English Aristosuchus
+from the Weald, and the American genera
+C&#339;lurus, Ceratosaurus, and others, in which the
+pubic bones, instead of uniting at their extremities,
+are pinched together from side to side, and unite
+down the lower part of their length, terminating
+in an expanded end like a shoe, which is seen to be
+a separate ossification, and probably formed by a pair
+<span class='pagenum'><a name="Page_205" id="Page_205">[Pg 205]</a></span>
+of ossifications joined in the median line. This small
+bone, which is below the pubes, and in these animals
+becomes blended with them, we may regard as a pair
+of prepubic bones like those of Pterodactyles and
+Crocodiles, except that they have lost the stalk-like
+portions, which in those animals are developed to
+compensate for the diminished length of the pubic
+bones. The prepubic bones may also be developed
+in Iguanodon, in which a pair of bones of similar
+form remains throughout life in advance of the
+pubes, as in Pterodactyles. In those Dinosauria
+with the Bird-like type of pelvis the pubic bone
+is exceptionally developed, sending one process
+backward and another process forward, so that
+there is a great gap between these diverging limbs
+to the bone. In the region behind the sternum to
+which the ribs were attached, and in front of the
+pelvis, is a pair of bones in Iguanodon shaped like
+the prepubic bones of Dimorphodon. They have
+sometimes been interpreted as a hinder part of the
+sternum, but may more probably be regarded as a
+pair of prepubic bones articulating each with the
+anterior process of the pubis (see <a href="#Fig_80">Fig. 80</a>). The small
+bones found at the extremities of the pubes in such
+carnivorous Dinosaurs as Aristosuchus are blended
+by bony union with the pubes. The bones in Iguanodon
+are placed behind the sternal region without
+any attachment for sternal ribs, and the expanded
+processes converge forwards from the stalk and unite
+exactly like the prepubic bones of Ornithosaurs.
+While this character, on the one hand, may link
+Pterodactyles with the Dinosaurs, on the other hand
+it may be a link between both those groups and the
+Crocodiles, in which the front pair of bones of the
+<span class='pagenum'><a name="Page_206" id="Page_206">[Pg 206]</a></span>
+pelvis has also appeared to be representative of the
+prepubic bones of Flying Reptiles (see <a href="#Fig_32">Fig. 32, p. 98</a>).</p>
+
+<div class="figcenter" style="width: 640px;">
+<a name="Fig_80" id="Fig_80"></a>
+<span class="caption">FIG. 80. &nbsp; DIAGRAM OF THE PELVIS SEEN FROM BELOW IN
+AN ORNITHOSAUR AND A DINOSAUR</span>
+<img src="images/i_241.jpg" width="640" height="441" alt="FIG. 80." title="FIG. 80." />
+</div>
+
+<p>The resemblances between Pterodactyles and Dinosaurs
+in the hind limb are not of less interest, though
+it is rather in the older Pterodactyles such as Dimorphodon,
+Pterodactylus, and Rhamphorhynchus that
+the resemblance is closest with the slender carnivorous
+Dinosaurs. They never have the head of
+the thigh bone, femur, separated from its shaft by a
+constricted neck, as in the Pterodactyles from the
+Chalk. In many ways the thigh bone of Dinosaurs
+tends towards being Avian; while that of Pterodactyles
+inclines towards being Mammalian, but with a
+tendency to be Bird-like in the older types, and to be
+Mammal-like in the most recent representatives of
+the group in the Chalk.</p>
+
+<p>The bones of the leg in Ornithosaurs, known as
+tibia and fibula, are remarkable for the circumstance
+first that they resemble Birds in the fibula being slender
+<span class='pagenum'><a name="Page_207" id="Page_207">[Pg 207]</a></span>
+and only developed in its upper part towards the
+femur, and secondly that in a genus like Dimorphodon
+this drum-stick bone has the two upper bones of
+the ankle blended with the tibia, so as to form a
+rounded pulley joint which is indistinguishable from
+that of a Bird (see <a href="#Page_102">p. 102</a>). There is a large number
+of Dinosaurs in which this remarkable distinctive
+character of Birds is also found. Only, Dinosaurs
+like Iguanodon, for instance, have the slender fibula
+as long as the tibia, and contributing to unite with the
+separate ankle bones of the similarly rounded pulley
+at the lower end. There are no Birds in which the
+tarsal bones remain separated and distinct throughout
+life. But in Pterodactylus from Solenhofen, as
+in a number of Dinosaurs, especially the carnivorous
+genera, the bones of the tarsus remain distinct throughout
+life, and never acquired such forms as would have
+enabled the ankle bone, termed astragalus, to embrace
+the extremity of the tibia, as it does in Iguanodon.
+Thus the resemblance of the Ornithosaur drum-stick
+is almost as close to Dinosaurs as to Birds.</p>
+
+<p>There is great similarity between Dinosaurs and
+Pterodactyles seen in the region of the instep, known
+as the metatarsus. These bones are usually four in
+number, parallel to each other, and similar in form.
+They are commonly longer than in Dinosaurs; but
+among some of the carnivorous Dinosaurs their
+length approximates to that seen in Pterodactyles.
+In neither group are the bones blended together by
+bony union, while they are always united in Birds, as
+in Oxen and similar even-hoofed mammals. Dinosaurs
+agree with Pterodactyles in maintaining the metatarsal
+bones separate, but they differ from them and agree
+with Birds frequently, in having the number of meta<span class='pagenum'><a name="Page_208" id="Page_208">[Pg 208]</a></span>tarsal
+bones reduced to three, as in Iguanodon, though
+Dinosaurs often have as many as five digits developed.</p>
+
+<p>The toe bones, the phalanges of these digits of the
+hind limb, are usually longer in Pterodactyles than in
+Dinosaurs, but they resemble carnivorous Dinosaurs
+in the forms of their sharp terminal bones for the claws,
+which are similarly compressed from side to side.</p>
+
+<p>So diverse are the functions of the fore limb in
+Dinosaurs and Pterodactyles, and so remarkably does
+the length of the metacarpal region of the back of the
+hand vary in the long-tailed and short-tailed Ornithosaurs,
+that there is necessarily a less close correspondence
+in that region of the skeleton between these two
+groups of animals; for the Pterodactyle fore limb is
+modified in relation to a function which can only be
+paralleled among Birds and Bats; and yet neither
+of those groups of animals approximates closely in
+this region of the skeleton to the Flying Reptile.
+Under all the modifications of structure which may
+be attributed to differences of function, some resemblance
+to Dinosaurs may be detected, which is
+best evident in the upper arm bone, humerus; is
+slight in the fore-arm bones, ulna and radius; and
+becomes lost towards the extremity of the limb.</p>
+
+<p>If the tendency of the thigh bone to resemble a
+Mammalian type of femur (<a href="#Page_100">p. 100</a>) is a fundamental,
+deep-seated character of the skeleton, it might be anticipated
+that a trace of Mammalian character would
+also be found in the humerus. For what the character
+is worth, the head of the humerus does show a closer
+approximation to a Monotreme Mammal than is seen
+in Birds, and is to some extent paralleled in those
+South African reptiles which approximate to Mammals
+most closely. Not the least remarkable of the many<span class='pagenum'><a name="Page_209" id="Page_209">[Pg 209]</a></span>
+astonishing resemblances of these light aerial creatures
+to the more heavy bodied Dinosaurs is the circumstance
+that the humerus in both groups makes a not
+dissimilar approach to that of certain Mammals.</p>
+
+<p>These illustrations may be accepted as demonstrating
+a relationship between the Ornithosaurs and
+Dinosaurs now compared, which can only be explained
+as results of influence of a common parentage
+upon the forms of the bones. But more interesting
+than resemblances of that kind is the similarity that
+may be traced in the way in which air is introduced
+into cavities in the bones in both groups. In some
+of the imperfectly known Dinosaurs, like Aristosuchus,
+C&#339;lurus, and Thecospondylus, the bone texture is as
+thin as in Pterodactyles, and the vertebr&aelig; are excavated
+by pneumatic cavities, which are amazing in
+size when compared with the corresponding structures
+in birds, for the vertebra is often hollowed out so that
+nothing remains but a thin external film like paper
+for its thickness. In the Dinosaurian genus C&#339;lurus
+this condition is as well marked in the tail and back
+as it is in the neck. The essential difference from
+Birds appears to be that in the larger carnivorous
+Dinosaurs the pneumatic condition of the bones is
+confined to the vertebral column; while Birds and
+Pterodactyles have the pneumatic condition more
+conspicuously developed in the limb bones. The
+pneumatic skeleton, however, appears to be absent
+from the herbivorous types like Iguanodon and all
+Dinosaurs which have the Bird-like form of pelvis,
+and are most Bird-like in the forms of bones of the
+hind limb. It is possible that some of the carnivorous
+Dinosaurs also possessed limb bones with pneumatic
+cavities. Many of those bones are hollow with very<span class='pagenum'><a name="Page_210" id="Page_210">[Pg 210]</a></span>
+thin walls. If their cavities were connected with the
+lungs the foramina are inconspicuous and unlike the
+immense holes seen in the sides of the vertebr&aelig;.</p>
+
+<p>According to the late Professor Marsh, the limbs
+of C&#339;lurus and its allies, which at present are imperfectly
+known, are in some cases pneumatic. Therefore
+there is a closer fundamental resemblance between
+some carnivorous Dinosaurs and Pterodactyles
+than might have been anticipated. But the skull of
+C&#339;lurus is unknown, and the fragments of the
+skeleton hitherto published are insufficient to do
+more than show that the two types were near in
+kindred, though distinct in habit. Each has elaborated
+a skeleton which owes much to the common
+stock which transmitted the vital organs, and the tendency
+of the bones to take special forms; but which
+also owes more than can be accurately measured to
+the action of muscles in shaping the bones and the
+influence of the mechanical conditions of daily life
+upon the growth of the bones in both of these orders
+of animals. Enough is known to prove that all Dinosaurs
+cannot be regarded as Ornithosaurs which have
+not acquired the power of flight; though the evidence
+would lead us to believe that the primitive Ornithosaur
+was a four-footed animal, before the wing finger
+became developed in the fore limb as a means of
+extending a patagial membrane, like the membrane
+which in the hind limb of Dimorphodon has bent the
+outermost digit of the foot upward and outward to
+support the corresponding organ of flight extending
+down the hind legs.</p>
+
+<p>It may thus be seen that the characters of Ornithosaurs
+which have already been spoken of as Reptilian,
+as distinguished from the resemblances to Birds, may<span class='pagenum'><a name="Page_211" id="Page_211">[Pg 211]</a></span>
+now with more accuracy be regarded as Dinosaurian.
+The Dinosaurs, like Pterodactyles, must be regarded
+as intermediate in some respects between
+Reptiles and Birds. The resemblances enumerated
+would alone constitute a partial transition from the
+Reptile to the Bird, although no Dinosaurs have
+organs of flight; many are heavily armoured with
+plates of bone, and few, if any, approximate in the
+technical parts of the skeleton to the Bird class,
+except in the hind limbs. Yet Dinosaurs have
+sometimes been regarded as standing to Birds in
+the relation of ancestors, or as parallel to an
+ancestral stock.</p>
+
+<p>Before an attempt can be made to estimate the
+mutual relation of the Flying Reptiles to Dinosaurs
+on the one hand, and to Birds on the other, it may
+be well to remember that the resemblance of such
+a Dinosaur as Iguanodon to a Bird in its pelvis and
+hind limb is not more remarkable than that of
+Pterodactyles to Birds in the shoulder-girdle and
+bones of the fore limb. The keeled sternum, the
+long, slender coracoid bones and scapul&aelig;, are absolutely
+Bird-like in most Ornithosaurs; and that region
+of the skeleton only differs from Birds in the absence
+of a furculum which represents the clavicles, and is
+commonly named the "merry-thought." The elongated
+bones of the fore-arm and the hand, terminating
+in three sharp claws, are characters in which the
+fossil bird Arch&aelig;opteryx resembles the Pterodactyle
+Rhamphorhynchus, a resemblance which extends to
+a similar elongation of the tail. It is remarkable
+that the resemblance should be so close, since Arch&aelig;opteryx
+affords the only bird's skeleton known to be
+contemporary which can be compared with the Solen<span class='pagenum'><a name="Page_212" id="Page_212">[Pg 212]</a></span>hofen
+Flying Reptiles. The resemblance may possibly
+be closer than has been imagined. The back of the
+head of Arch&aelig;opteryx is imperfectly preserved in
+the region of the quadrate bone, malar arch, and
+temporal vacuity. And till these are better known
+it cannot be affirmed that the back of the head is
+more Reptilian in Pterodactyles than in the oldest
+Birds. The side of the head in Arch&aelig;opteryx is
+distinguished by the nostril being far forward, the
+vacuity in front of the orbit being as large as in
+the Pterodactyle Scaphognathus from Solenhofen
+and other long-tailed Pterodactyles.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_213" id="Page_213">[Pg 213]</a></span></p>
+<h2><a name="CHAPTER_XVIII" id="CHAPTER_XVIII"></a><small>CHAPTER XVIII</small><br /><br />
+
+HOW PTERODACTYLES MAY
+HAVE ORIGINATED</h2>
+
+
+<p>Ornithosauria have many characters inseparably
+blended together which are otherwise
+distinctive of Reptiles, Birds, and Mammals, and associated
+with peculiar structures which are absent
+from all other animals. They are not quite alone in
+this incongruous combination of different types of
+animals in the same skeleton. Dinosaurs, which were
+contemporary with Ornithosaurs, approximate to them
+in blending characters of Birds with the structure of
+a Reptile and something of a Mammal in one animal.
+If an Ornithosaur is Reptilian in its backbone, in the
+articular ends of each vertebra having the cup in
+front and ball behind in the manner of Crocodiles,
+Serpents, and many Lizards, a Dinosaur like Iguanodon,
+which had the reversed condition of ball in
+front and cup behind in its early vertebr&aelig;, may be
+more Mammalian than Avian in a corresponding
+resemblance of the bones to the neck in hoofed
+Mammals. But while Pterodactyles are sometimes
+Mammalian in having the head of the thigh bone
+moulded as in carnivorous Mammals and Man, the
+corresponding bone in a Dinosaur is more like that<span class='pagenum'><a name="Page_214" id="Page_214">[Pg 214]</a></span>
+of a Bird. And while the Pterodactyle shoulder-girdle
+is often absolutely Bird-like, that region in
+Dinosaurs can only be paralleled among Reptiles.</p>
+
+<p>Such combinations of diverse characters are not
+limited to animals which are extinct. There were
+not wanting scientific men who regarded the Platypus
+of Australia, when first sent to Europe, as an
+ingenious example of Eastern skill, in which an
+animal had been compounded artificially by blending
+the beak of a Bird with the body of a Mammal.
+Fuller knowledge of that remarkable animal has
+continuously intensified wonder at its combination
+of Mammal, Bird, and Reptile in a single animal.
+It has broken down the theoretical divisions between
+the higher Vertebrata, demonstrating that a
+Mammal may lay eggs like a Reptile or Bird, that
+the skull may include the reptilian characters of the
+malar arch and pre-frontal and post-frontal bones,
+otherwise unknown in Mammals and Birds. The
+groups of Mammals, Birds, and Reptiles now surviving
+on the earth prove to be less sharply defined
+from each other when the living and extinct types
+are considered together. But in Pterodactyles,
+Mammal Bird and Reptile lose their identity, as three
+colours would do when unequally mixed together.</p>
+
+<p>This mingling of characteristics of different animals
+is not to be attributed to interbreeding, but is the
+converse of the combination of characters found in
+hybrid animals. It is no exaggeration to say that
+there is a sense in which Mammal, Bird, Reptile, and
+the distinctive structures of the Ornithosaur, have
+simultaneously developed from one egg, in the body
+of one animal.</p>
+
+<p>The differences between those vertebrate types of<span class='pagenum'><a name="Page_215" id="Page_215">[Pg 215]</a></span>
+animals consist chiefly in the way in which their
+organisation is modified, by one strain of characters
+being eliminated so that another becomes predominant,
+while a distinctive set of structures is elaborated
+in each class of animals. The earlier geological history
+of the higher Vertebrata is very imperfectly
+known, but the evidence tends to the inference that
+the older representatives of the several classes approximate
+to each other more closely than do their
+surviving representatives, so that in still earlier ages
+of time the distinction between them had not become
+recognisable. The relation of the great groups of
+animals to each other, among Vertebrata, is essentially
+a parallel relation, like the colours of the solar spectrum,
+or the parallel digits of the hand. It was
+natural, when only the surviving life on the earth was
+known, to imagine that animals were connected in a
+continuous chain by successive descent, but Mammals
+have given no evidence of approximation to Birds;
+and Birds discover no evidence that their ancestors
+were Reptiles, in the sense in which that word is used
+to define animals which now exist on the earth.
+When the variation which animals attain in their
+maturity and exhibit in development from the egg
+was first realised, it was imagined that Nature, by
+slow summing up and accumulation of differences
+which were observed, would so modify one animal
+type that it would pass into another. There is little
+evidence to support belief that the changes between
+the types of life have been wrought in that way.
+The history of fossil animals has not shown transitions
+of this kind from the lower to higher Vertebrata,
+but only intermediate, parallel groups of animals,
+analogous to those which survive, and distinct from<span class='pagenum'><a name="Page_216" id="Page_216">[Pg 216]</a></span>
+them in the same way as surviving groups are distinct
+from each other. The circumstance that Mammals,
+Birds, and Reptiles are all known low down in the
+Secondary epoch of geological time, is favourable to
+the idea of their history being parallel rather than
+successive. Such a conception is supported by the
+theory of elimination of characters from groups of
+animals as the basis of their differentiation. This loss
+appears always to be accompanied by a corresponding
+gain of characters, which is more remarkable in
+the soft, vital organs than in the skeleton. The gain
+in higher Vertebrates in the bones is chiefly in the
+perfection of joints at their extremities; but the gain
+in brain, lungs, heart, and other soft parts is an
+elaboration of those structures and an increase in
+amount of tissue.</p>
+
+<p>The resemblances of Ornithosaurs to Mammals are
+the least conspicuous of their characters. Those seen
+in the upper arm bone and thigh bone are manifestly
+not derived from Mammals. They cannot be explained
+as adaptations of the bones to conditions of
+existence, because there is no community of habit to
+be inferred between Pterodactyles and Mammals, in
+which the bones are in any way comparable.</p>
+
+<p>Other fossil animals show that a fundamentally
+Reptilian structure is capable of developing in the
+Mammalian direction in the skull, backbone, shoulder-girdle,
+hip-girdle, and limbs, so as to be uniformly
+Mammalian in its tendencies. This is proved by
+tracing the North American Texas fossils named
+Labyrinthodonts, through the South African Theriodonts,
+towards the Monotremata and other Mammalia.
+Just as those animals have obliterated all traces of
+the Bird from their skeletons, Birds have obliterated<span class='pagenum'><a name="Page_217" id="Page_217">[Pg 217]</a></span>
+the distinctive characters of Mammals. The Ornithosaur
+has partially obliterated both. With a skull and
+backbone marked by typical characters of the Reptile,
+it combines the shoulder-girdle and hip-girdle of a
+Bird, with characters in the limbs which suggest both
+those types in combination with Mammals.</p>
+
+<p>The bones have been compared in the skeleton of
+each order of existing Reptiles, and found to show
+side by side with their peculiar characters not only
+resemblances to the other Reptilia, but an appreciable
+number of Mammalian and Avian characters in their
+skeletons. The term "crocodile," for example, indicates
+an animal in which the skeleton is dominated
+by one set of peculiar characters. Crocodiles retain
+enough of the characteristics of several other orders
+of reptiles to show that an animal sprung from the
+old Crocodile stock might diverge widely from existing
+Crocodiles by intensifying what might be termed
+its dormant characters in the Crocodile skeleton.
+Comparing animals together bone by bone it is
+possible to value the modifications of form which
+they put on, and the resemblances between them,
+so as to separate the inherited wealth of an animal's
+affinities with ancestors or collateral groups, from
+the peculiar characters which have been acquired
+as an increase based upon its typical bony possessions
+or osteological capital. There is no part of the Pterodactyle
+skeleton which is more distinctly modified
+than the head of the upper arm bone, which fits
+into the socket between the coracoid bone and the
+shoulder-blade. The head of the humerus, as the
+articular part is named, is somewhat crescent-shaped,
+convex on its inner border, and a little concave on
+its outer border, and therefore unlike the ball-shaped<span class='pagenum'><a name="Page_218" id="Page_218">[Pg 218]</a></span>
+head of the upper arm bone in Man and the higher
+Mammals. It is much more nearly paralleled in the
+little group of Monotremata allied to the living
+Ornithorhynchus. In that sense the head of the
+humerus in a Pterodactyle has some affinity with the
+lowest Mammalia, which approach nearest to Reptiles.
+The character might pass unregarded if it were not
+found in more striking development in fossil Reptiles
+from Cape Colony, which from having teeth like
+Mammals are named Theriodontia. In several of
+those South African reptiles the upper arm bone
+approaches closer to the humerus in Ornithosaurs
+than to Ornithorhynchus. Such coincidences of
+structure are sometimes dismissed from consideration
+and placed beyond investigation by being termed
+adaptive modifications; but there can be no hope
+of finding community of habit between the burrowing
+Monotreme, the short-limbed Theriodont, and
+the flying Pterodactyle which might have caused
+this articular part of the upper arm bone to acquire
+a form so similar in animals constructed so differently.
+If the resemblance in the humerus to Monotremes
+in this respect is not to be attributed to
+burrowing, neither can the crescent form of its upper
+articulation be attributed to flight; for in Birds the
+head of the bone is compressed, but always convex,
+and Bats fly without any approach to the Pterodactyle
+form in the head of the humerus. This
+apparently trivial character may from such comparisons
+be inferred to be something which the way
+of life of the animal does not sufficiently account for.
+These deepest-seated parts of the limbs are slow to
+adapt themselves to changing circumstances of existence,
+and retain their characters with moderate<span class='pagenum'><a name="Page_219" id="Page_219">[Pg 219]</a></span>
+variation of the bones in each of the orders or classes
+of animals. It therefore is safer to regard Mammalian
+characters, as well as the resemblances which
+Pterodactyles show to other kinds of animals, as due
+to inheritance from a time when there was a common
+stock from which none of these animals which have
+been considered had been distinctly elaborated.</p>
+
+<p>A few characters of Ornithosaurs are regarded as
+having been acquired, because they are not found
+in any other animals, or have been developed only
+in a portion of the group. The most obvious of
+these is the elongated wing finger; but in some
+genera, like Dimorphodon, there is also a less elongation
+of the fifth digit of the foot, and perhaps in
+all genera there is a backward development of the
+first digit of the hand, which is without a claw, and
+therefore unlike the clawed digit of a Bat. An
+acquired character of another kind, which is limited
+to the Cretaceous genera, is seen in the shoulder-blade
+being directed transversely outward, so that
+its truncated end articulates by a true joint with the
+early vertebr&aelig; of the back, and defended the cavity
+inclosed by the ribs by a strong bony external arch.
+And finally, as the animals later in time acquire short
+tails, and relatively longer limbs, the bones of the
+back of the hand, termed metacarpals, acquire
+greater and distinctive length, which is not seen in
+the long-tailed types like Rhamphorhynchus.</p>
+
+<p>These and such-like acquired characters distinguish
+the class of animals from all groups with
+which it may be compared, and mark the possible
+limits of variation of the skeleton within the
+boundary of the order. But no further variation of
+these parts of the skeleton could make a transition<span class='pagenum'><a name="Page_220" id="Page_220">[Pg 220]</a></span>
+to another order of animals, or explain how the
+Pterodactyles came into existence, because the characters
+which separate orders and classes of animals
+from each other differ in kind from those which
+separate smaller groups, named genera and species,
+of which the order is made up. The accumulation
+of the characters of genera will not sum up into the
+characters of an order or class.</p>
+
+<p>In making the division of Vertebrate animals into
+classes the skeleton is often almost ignored. Its
+value is entirely empirical and based upon the
+observed association of the various forms of bones
+with the more important characters of the brain and
+other vital organs. What is understood as a Mammalian
+or Avian character in the skeleton is the form
+of bone which is found in association with the soft
+vital organs which constitute an animal a Mammal
+or a Bird.</p>
+
+<p>The characters which theoretically define a Mammal
+appear to be the enormous overgrowth of the cerebral
+hemispheres of the brain by which the cerebrum
+comes into contact with the cerebellum, as among
+Birds. This character distinguishes both groups of
+animals from all Reptiles, recent and fossil. But in
+examining the mould of the interior of the brain
+case it is rare to have the bones fitting so closely
+to the brain as to prove that the lateral expansion
+below the cerebrum and cerebellum is formed by
+the optic lobes of the brain. Otherwise the brain
+of a Pterodactyle might be as like to the brain of
+Ornithorhynchus as it is like that of a Bird (<a href="#Fig_19">Fig. 19</a>).
+But it is precisely in this condition of arrangement
+of the parts of the brain that the specimens appear
+to be most clear. The lateral mass of brain in<span class='pagenum'><a name="Page_221" id="Page_221">[Pg 221]</a></span>
+specimens of Ornithosaurs from the Lower Secondary
+rocks appears to be transversely divided into back
+and front parts, which may be thought to correspond
+to the structures in a Mammal brain named
+<i>corpora quadrigemina</i>, but to be placed as the optic
+lobes are placed in Birds, and to have relatively
+greater dimensions than in Mammals. No evidence
+has been observed of this transverse division of the
+optic lobes of the brain in Pterodactyles from the
+Chalk and Cretaceous rocks, and so far as the evidence
+goes this part of the brain was shaped as in birds,
+but rather smaller.</p>
+
+<p>The brain is the only soft organ in which a Mammalian
+character could be evidenced. The uniformity
+in character of the brain throughout the group in
+Mammals is remarkable, in reference to the circumstance
+that the reproduction varies in type; the lowest,
+or Monotreme division, being oviparous. If there is
+no necessary connexion between the Mammalian
+brain and the prevalent condition under which the
+young are produced alive, it may be affirmed also
+that there is no necessary connexion between the
+form of the brain and the form of the bones, since
+the brain cavity in Theriodont reptiles shows no
+resemblance to that of a Mammal, while the bones
+are in so many respects only paralleled among
+Monotremata and Mammalia. The variety of forms
+which the existing Mammalian orders of animals
+assume, shows the astonishing range of structure of
+the skeleton which may coexist with the Mammalian
+brain. And therefore we are led to the conclusion
+that any other fundamental modification of brain&mdash;such
+as distinguishes the class of Birds&mdash;might also
+be associated with forms and structures of the skele<span class='pagenum'><a name="Page_222" id="Page_222">[Pg 222]</a></span>ton
+which would vary in similar ways. In other
+words, if for convenience we define a Mammal by
+its form of brain, structure of the heart and lungs,
+and provision for nutrition of the young, without
+regard to the covering of the skin, which varies
+between the scales of a pangolin and the practically
+naked skin of the whale&mdash;a bird might be also
+defined by its peculiar conditions of brain and lungs,
+without reference to the feathered condition of the
+skin, though the feathered condition extends backward
+in time to the Upper Secondary rocks, as seen
+in the Arch&aelig;opteryx.</p>
+
+<p>The Avian characters of Pterodactyles are the predominant
+parts of their organisation, for the conditions
+of the brain and lungs shown by the moulds
+of the brain case and the thin hollow bones with
+conspicuous pneumatic foramina, give evidence of
+a community of vital structures with Birds, which
+is supported by characters of the skeleton. If any
+classificational value can be associated with the distribution
+of the pneumatic foramina as tending to
+establish membership of the same class for animals
+fashioned on the same plan of soft organs, the
+evidence is not weakened when a community of
+structures is found to extend among the bones to
+such distinctive parts of the skeleton as the sternum,
+shoulder-girdle, bones of the fore-arm and fore-leg;
+for in all these regions the Pterodactyle bones are
+practically indistinguishable from those of Birds.
+This is the more remarkable because other parts of
+the skeleton, such as the humerus and pelvis, show
+a partial resemblance to Birds, while the parts which
+are least Avian, like the neck bones, have no tendency
+to vary the number of the vertebr&aelig;, in the<span class='pagenum'><a name="Page_223" id="Page_223">[Pg 223]</a></span>
+way which is common among Birds, following more
+closely the formula of the seven cervical vertebr&aelig; of
+Mammals.</p>
+
+<p>It would therefore appear from the vital community
+of structures with Birds, that Pterodactyles
+and Birds are two parallel groups, which may be
+regarded as ancient divergent forks of the same
+branch of animal life, which became distinguished
+from each other by acquiring the different condition
+of the skin, and the structures which were developed
+in consequence of the bony skeleton ministering to
+flight in different ways; and with different habit of
+terrestrial progression, this extinct group of animals
+acquired some modifications of the skeleton which
+Birds have not shown. There is nothing to suggest
+that Pterodactyles are a branch from Birds, but their
+relation to Birds is much closer, so far as the skeleton
+goes, than is their relation with the flightless Dinosaurs,
+with which Birds and Pterodactyles have many
+characters in common.</p>
+
+<p>On the theory of elimination of character which
+I have used to account for the disappearance of some
+Mammalian characters from the Pterodactyle, that
+loss is seen chiefly in the removal of the parts which
+have left a Reptilian articulation of the lower jaw
+with the skull, and the articulation of the vertebr&aelig;
+throughout the vertebral column by a modified cup-and-ball
+form of joint. The furculum of the Bird is
+always absent from the Pterodactyle. No specimen
+has shown recognisable clavicles or collar-bones.
+Judged by the standard of existing life, Pterodactyles
+belong to the same group as Birds, on the
+evidence of brain and lungs, but they belong to
+a different group on account of the dissimilar<span class='pagenum'><a name="Page_224" id="Page_224">[Pg 224]</a></span>
+modifications of the skeleton and apparent absence
+of feathers from the skin.</p>
+
+<p>The most impressive facts in the Pterodactyle
+skeleton, in view of these affinities, are the structures
+which it has in common with Reptiles. Some structures
+are fundamental, like the cup-and-ball articulation
+of the vertebr&aelig;, which is never found in birds
+or mammals. Although not quite identical with the
+condition in any Reptile, this structure is approximately
+Lizard-like or Crocodile-like in the cup-and-ball
+character. It shows that the deepest-seated part
+of the skeleton is Reptile-like, though it may not be
+more Reptilian than is the vertebral column of a
+Mammal, if comparison is made between Mammals
+and extinct groups of animals known as Reptiles,
+such as Dinosaurs and Theriodontia.</p>
+
+<p>The orders of animals which have been included
+under the name Reptilia comprise such different
+structural conditions of the parts of the skeleton
+which may be termed reptilian in Ornithosaurs, that
+there is good reason for regarding the cup-and-ball
+articulation as quite a distinctive Reptilian specialisation,
+in the same sense that the saddle-shaped articulation
+between the bodies of adjacent vertebr&aelig; in
+a bird is an Avian specialisation. From the theoretical
+point of view the Ornithosaur acquired its Reptilian
+characters simultaneously with its Avian and Mammalian
+characters.</p>
+
+<p>There is nothing in the structure of the skeleton
+of the Dinosauria, to which Ornithosaurs approximate
+in several parts of the body, which would help to
+explain the cup-and-ball articulation of the backbone,
+if the Flying Reptile were supposed to be an offshoot
+from the carnivorous Dinosaurs.<span class='pagenum'><a name="Page_225" id="Page_225">[Pg 225]</a></span></p>
+
+<p>The elimination of Reptile characters from so much
+of the skeleton, and the substitution for them of the
+characters of Birds and Mammals, would be of exceptional
+interest if there had been any ground for
+regarding the flying animal as more nearly related to
+a Reptile than to a Bird. But if the evidence from
+the form of the brain and nature of the pneumatic
+organs seen in the limb bones accounts for the Avian
+features of the skeleton, the Reptilian condition of the
+vertebral column helps to show a capacity for variation,
+and that the fixity of type and structure, which
+the skeleton of the modern Bird has attained, is not
+necessarily limited to or associated with the vital
+organs of Birds.</p>
+
+<p>The variation of the cup-and-ball articulation in
+the neck of a Chelonian, which makes the third
+vertebra cupped behind, the fourth bi-convex, the
+fifth cupped in front, and the sixth flattened behind,
+shows that too much importance may be attached
+to the mode of union of these bones in Serpents,
+Crocodiles, and those Lizards which have the cup in
+front; for while in Lizards the anterior cup, oblique and
+depressed, is found in most of its groups, the Geckos
+show no trace of the cup-and-ball structure, and in
+that respect resemble the Hatteria of New Zealand.</p>
+
+<p>If, therefore, the cup-and-ball articulation of vertebr&aelig;
+in Ornithosauria has any significance as a mark
+of affinity to Reptiles, it could only be in approximation
+to those living Reptiles which possess the same
+character, and would have it on the hypothesis that
+both have preserved the structure by descent from an
+earlier type of animal. This hypothesis is negatived
+by the fact that the cup-and-ball articulation is unknown
+in the older fossil Reptiles.<span class='pagenum'><a name="Page_226" id="Page_226">[Pg 226]</a></span></p>
+
+<p>Although the articulation for the lower jaw with
+the skull in Ornithosaurs is only to be paralleled
+among Reptiles, the structure is adapted to a brain
+case which is practically indistinguishable from that
+of a Bird, except for the postorbital arch.</p>
+
+<p>The hypothesis of descent, therefore, becomes impossible,
+in any intelligible form, in explanation
+of distinctive character of the skeleton. The hypothesis
+of elimination may also seem to be insufficient,
+unless the potential capacity for new development be
+recognised as concurrent, and as capable of modifying
+each region of the skeleton, or hard parts of the
+animal, in the same way that the soft organs may be
+modified. From which we infer that all structures,
+which distinguish the several grades of organisation
+in modern classifications, soft parts and hard parts
+alike, may come into existence together, in so far
+as they are compatible with each other, in any class
+or ordinal division of animals.</p>
+
+<p>Although the young Mammal passes through a
+stage of growth in which the brain may be said to be
+Reptilian, there is no good ground for inferring that
+Mammal or Bird type of skeleton was developed later
+in time than that of Reptiles. The various types of
+Fishes have the brains in general so similar to those
+of Reptiles that it is more intelligible for all the
+vertebrate forms of brain to have differentiated at
+the same time, under the law of elimination of characters,
+than that there should be any other bond of
+union between the classes of animals.</p>
+
+<p>If we ask what started the Ornithosauria into
+existence, and created the plan of construction of
+that animal type, I think science is justified in boldly
+affirming that the initial cause can only be sought<span class='pagenum'><a name="Page_227" id="Page_227">[Pg 227]</a></span>
+under the development of patagial membranes, such
+as have been seen in various animals ministering to
+flight. Such membranes, in an animal which was
+potentially a Bird in its vital organs, have owed development
+to the absence of quill feathers. Thus
+the wing membrane may be the cause for the chief
+differences of the skeleton by which Ornithosaurs
+are separated from Birds, for the stretch of wing in
+one case is made by the skin attached to the bones,
+and in the other case by feathers on the skin so
+attached as to necessitate that the wing bones have
+different proportions from Ornithosaurs.</p>
+
+<p>It is a well-known observation that each great
+epoch of geological time has had its dominant forms
+of animal life, which, so far as the earth's history is
+known now, came into existence, lived their time,
+and were seen no more. In the same way the
+smaller groups of species and genera included in an
+ordinal group of animals or class have abounded,
+giving a tone to the life of each geological formation,
+until the vitality of the animal is exhausted, and the
+species becomes extinct or ceases to preponderate.
+This process is seen to be still modifying the life on
+the earth, when some kinds of animals and plants
+are introduced to new conditions. Plants appear to
+wage successful war more easily than animals. The introduction
+of the Cactus in some parts of Cape Colony
+has locally modified both the fauna and flora, just
+as the Anacharis introduced into England spread
+from Cambridge over the whole country, and became
+for many years the predominant form of plant life
+in the streams. The Rabbit in Australia is a historic
+pest. Something similar to this physical fertility
+and increase appears to take place under new cir<span class='pagenum'><a name="Page_228" id="Page_228">[Pg 228]</a></span>cumstances
+in certain organs within the bodies of
+animals, by the development of structures previously
+unknown. A familiar example is seen in the internal
+anatomy of the Trout introduced into New Zealand,
+where the number of pyloric appendages about the
+stomach has become rapidly augmented, while the
+size and the form of the animal have changed. The
+rapidity with which some of these changes have been
+brought about would appear to show that Nature is
+capable of transforming animals more rapidly than
+might have been inferred from their uniform life
+under ordinary circumstances. Growth of the vital
+organs in this way may modify the distinctive form
+of any vital organ, brain or lungs, and thus as a consequence
+of modification of the internal structures due
+to changes of food and habit, bring a new group of
+animals into existence. And just as the group of
+animals ceases to predominate after a time, so there
+comes a limit to the continued internal development
+of vital structures as their energy fails, for each organ
+behaves to some extent like an independent organism.</p>
+
+<p>Under such explanations of the mutual relations of
+the parts of animals, and groups of animals, time
+ceases to be a factor of primary importance in their
+construction or elaboration. The supposed necessity
+for practically unlimited time to produce changes in
+the vital organs which separate animals into great
+orders or classes is a nightmare, born of hypothesis,
+and may be profitably dismissed. The geological
+evidence is too imperfect for dogmatism on speculative
+questions; but the nature of the affinities of
+Ornithosaurs to other animals has been established
+on a basis of comparison which has no need of
+theory to justify the facts. It is not improbable that<span class='pagenum'><a name="Page_229" id="Page_229">[Pg 229]</a></span>
+the primary epoch of time, even as known at present,
+may be sufficiently long to contain the parent races
+from which Ornithosaurs and all their allies have
+arisen.</p>
+
+<p>In thus stating the relation of Ornithosaurs to
+other animals the Flying Reptile has been traced
+home to kindred, though not to its actual parents or
+birthplace. There is no geological history of the
+rapid or gradual development of the wing finger, and
+although the wing membrane may be accepted as
+its cause of existence, the wing finger is powerfully
+developed in the oldest known Pterodactyles as in
+their latest representatives.</p>
+
+<p>Pterodactyles show singularly little variation in
+structure in their geological history. We chronicle
+the loss of the tail and loss of teeth. There is also
+the loss of the outermost wing digit from the hind
+foot as a supporter of the wing membrane. But the
+other variations are in the length of the metacarpus,
+or of the neck, or head. One of the fundamental
+laws of life necessitates that when an animal type
+ceases to adapt its organisation and modify its
+structures to suit the altered circumstances forced
+upon it by revolutions of the earth's surface its life's
+history becomes broken. It must bend or break.</p>
+
+<p>The final disappearance of these animals from the
+earth's history in the Chalk may yet be modified
+by future discoveries, but the Flying Reptiles have
+vanished, in the same way as so many other groups
+of animals which were contemporary with them in
+the Secondary period of time. Such extinctions
+have been attributed to catastrophes, like the submergence
+of land, so that the habitations of animals
+became an area gradually decreasing in size, which<span class='pagenum'><a name="Page_230" id="Page_230">[Pg 230]</a></span>
+at last disappeared. It appears also to be a law of
+life, illustrated by many extinct groups of animals,
+that they endure for geological ages, and having
+fought their battle in life's history, grow old and unable
+to continue the fight, and then disappear from
+the earth, giving place to more vigorous types adapted
+to live under new conditions.</p>
+
+<p>The extinct Pterodactyles hold a relation to Birds
+in the scheme of life not unlike that which Monotremata
+hold to other Mammals. Both are remarkable
+for the variety of their affinities and resemblances
+to Reptiles. The Ornithosauria have long passed
+away; the Monotremes are nearing extinction. Both
+appear to be supplanted by parallel groups which
+were their contemporaries. Birds now fill the earth
+in a way that Flying Reptiles never surpassed; but
+their flight is made in a different manner, and the
+wing is extended to support the animal in the air,
+chiefly by appendages to the skin.</p>
+
+<p>If these fossils have taught that Ornithosaurs have
+a community of soft vital organs with Dinosaurs and
+Birds, they have also gone some way towards proving
+that causes similar to those which determined the
+structural peculiarities of their bony framework,
+originated the special forms of respiratory organs
+and brain which lifted them out of association with
+existing Reptiles.</p>
+
+<p>&nbsp;</p>
+
+<p>These old flying animals sleep through geological
+ages, not without honour, for the study of their story
+has illuminated the mode of origin of animals which
+survive them, and in cleaving the rocks to display
+their bones we have opened a new page of the book
+of life.</p>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_231" id="Page_231">[Pg 231]</a></span></p>
+<h2><a name="APPENDIX" id="APPENDIX"></a>APPENDIX</h2>
+
+
+<p>The best public collections of Ornithosaurian remains in
+England are in the British Museum (Natural History);
+Museum of Practical Geology, Royal College of Surgeons;
+the University Museum, Oxford; Geological Museum,
+Cambridge; and the Museum of the Philosophical Society
+at York.</p>
+
+<p>Detailed descriptions and original figures of the principal
+specimens mentioned or referred to may be found in
+the following writings:&mdash;</p>
+
+<div class="blockquot"><p class="noidt">
+H. v. Meyer, <i>Reptilien aus dem Lithograph</i>. <i>Schiefer</i>. 1859. Folio.<br />
+v. Quenstedt, <i>Pterodactylus suevicus</i>. 1855. 4to.<br />
+Goldfuss, <i>Nova Acta Leopold</i>. XV.<br />
+v. Munster, <i>Nova Acta Leopold</i>. XV.<br />
+A. Wagner, <i>Abhandl. Bayerischen Akad.</i>, vi., viii.<br />
+Cuvier, <i>Annales du Museum</i>, xiii. 1809.<br />
+<span style="margin-left: 1em;">"&nbsp; &nbsp; &nbsp;  <i>Ossemens fossiles</i>, v. 1824.</span><br />
+Buckland, <i>Geol. Trans.</i>, ser. 2, iii.<br />
+R. Owen, <i>Pal&aelig;ontographical Society</i>. 1851, 1859, 1860, 1870, 1874.<br />
+K. v. Zittel, <i>Pal&aelig;ontographica</i>, xxix. 1882.<br />
+T. C. Winkler, <i>Mus. Teyler Archives</i>. 1874, 1883.<br />
+Oscar Fraas, <i>Pal&aelig;ontographica</i>, xxv. 1878.<br />
+Anton Fritsch, <i>B&ouml;hm. Gesell. Sitzber</i>. 1881.<br />
+R. Lydekker, <i>Catalogue of Fossil Reptilia in British Museum</i>, I. 1888.<br />
+O. C. Marsh, <i>Amer. Jour. Science</i>. 1882, 1884.<br />
+S. W. Williston, <i>Kansas University Quarterly</i>. 1893, 1896.<br />
+<span class='pagenum'><a name="Page_232" id="Page_232">[Pg 232]</a></span>E. T. Newton, <i>Phil. Trans. Royal Soc.</i> 1888, 1894.<br />
+H. G. Seeley, <i>Ornithosauria</i>. 8vo. 1870.<br />
+<span style="margin-left: 2em;">"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;  <i>Annals and Mag. Natural Hist.</i> 1870, 1871, 1890, 1891.</span><br />
+<span style="margin-left: 2em;">"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;  <i>Linn. Society</i>. 1874, 1875.</span><br />
+<span style="margin-left: 2em;">"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;  <i>Geol. Mag.</i> 1881.</span><br />
+Felix Pleininger, <i>Pal&aelig;ontographica</i>. 1894, 1901.<br />
+</p></div>
+
+
+
+<hr style="width: 65%;" />
+<p><span class='pagenum'><a name="Page_233" id="Page_233">[Pg 233]</a></span></p>
+<h2><a name="INDEX" id="INDEX"></a>INDEX</h2>
+
+
+<div class="blockquot"><p class="noidt">
+<b>A</b><br />
+<br />
+Abdominal ribs, <a href="#Page_85">85</a>, <a href="#Page_154">154</a><br />
+<br />
+Accumulation of characters, <a href="#Page_220">220</a><br />
+<br />
+Acetabulum, <a href="#Page_95">95</a><br />
+<br />
+Acquired characters, <a href="#Page_219">219</a><br />
+<br />
+Adjacent land, <a href="#Page_136">136</a><br />
+<br />
+Air cells, <a href="#Page_10">10</a>, <a href="#Page_48">48</a><br />
+<br />
+Albatross, <a href="#Page_23">23</a>, <a href="#Page_36">36</a>, <a href="#Page_176">176</a><br />
+<br />
+Alligator, brain, <a href="#Page_53">53</a>;<br />
+<span style="margin-left: 1em;">pelvis, <a href="#Page_98">98</a></span><br />
+<br />
+American Greensand, <a href="#Page_185">185</a><br />
+<br />
+&mdash; ornithosaurs, <a href="#Page_87">87</a>, <a href="#Page_126">126</a><br />
+<br />
+Amphibia, <a href="#Page_4">4</a>, <a href="#Page_191">191</a><br />
+<br />
+Anabas, <a href="#Page_17">17</a><br />
+<br />
+Anacharis, <a href="#Page_227">227</a><br />
+<br />
+Anchisaurus, <a href="#Page_199">199</a><br />
+<br />
+Angle of lower jaw, <a href="#Page_75">75</a><br />
+<br />
+Ankle bones, <a href="#Page_103">103</a>, <a href="#Page_195">195</a>, <a href="#Page_207">207</a><br />
+<br />
+Anomodonts, <a href="#Page_192">192</a><br />
+<br />
+Ant-eater of Africa, <a href="#Page_142">142</a>;<br />
+<span style="margin-left: 1em;">India, <a href="#Page_40">40</a>;</span><br />
+<span style="margin-left: 1em;">South America, <a href="#Page_40">40</a>, <a href="#Page_185">185</a></span><br />
+<br />
+Apteryx, lungs, <a href="#Page_48">48</a>;<br />
+<span style="margin-left: 1em;">pelvis, <a href="#Page_95">95</a></span><br />
+<br />
+Aquatic mammals, <a href="#Page_141">141</a><br />
+<br />
+Aramis, scapular arch, <a href="#Page_113">113</a><br />
+<br />
+Arch&aelig;opteryx, <a href="#Page_58">58</a>, <a href="#Page_76">76</a>, <a href="#Page_104">104</a>, <a href="#Page_130">130</a>, <a href="#Page_197">197</a>, <a href="#Page_211">211</a><br />
+<br />
+Aristosuchus, <a href="#Page_129">129</a>, <a href="#Page_190">190</a>, <a href="#Page_205">205</a>, <a href="#Page_209">209</a><br />
+<br />
+Armadillo, <a href="#Page_40">40</a>, <a href="#Page_141">141</a><br />
+<br />
+Articulation of the jaw, <a href="#Page_12">12</a>, <a href="#Page_75">75</a><br />
+<br />
+Ashwell, <a href="#Page_177">177</a><br />
+<br />
+Atlantosaurus, <a href="#Page_202">202</a><br />
+<br />
+Atlas and axis, <a href="#Page_80">80</a>, <a href="#Page_81">81</a><br />
+<br />
+Aves, <a href="#Page_190">190</a><br />
+<br />
+Avian characters, <a href="#Page_220">220</a>, <a href="#Page_222">222</a><br />
+<br />
+<br />
+<b>B</b><br />
+<br />
+Backbone, <a href="#Page_78">78</a>, <a href="#Page_84">84</a><br />
+<br />
+Banz, <a href="#Page_148">148</a><br />
+<br />
+Barbastelle, <a href="#Page_25">25</a><br />
+<br />
+Barrington, <a href="#Page_177">177</a><br />
+<br />
+Barton, <a href="#Page_177">177</a><br />
+<br />
+Bat, <a href="#Page_38">38</a>, <a href="#Page_110">110</a>, <a href="#Page_197">197</a>;<br />
+<span style="margin-left: 1em;">sternum of, <a href="#Page_107">107</a>;</span><br />
+<span style="margin-left: 1em;">metacarpus, <a href="#Page_128">128</a></span><br />
+<br />
+Bavaria, <a href="#Page_156">156</a>, <a href="#Page_185">185</a><br />
+<br />
+Beak, horny, <a href="#Page_74">74</a>, <a href="#Page_178">178</a><br />
+<br />
+Bear, skull of, <a href="#Page_12">12</a>;<br />
+<span style="margin-left: 1em;">femur, <a href="#Page_100">100</a></span><br />
+<br />
+Bel and the Dragon, <a href="#Page_15">15</a><br />
+<br />
+Belodon, <a href="#Page_202">202</a><br />
+<br />
+Bird, <a href="#Page_80">80</a>, <a href="#Page_110">110</a>, <a href="#Page_120">120</a><br />
+<br />
+&mdash; resemblances, <a href="#Page_63">63</a>, <a href="#Page_65">65</a>, <a href="#Page_71">71</a>, <a href="#Page_95">95</a>, <a href="#Page_102">102</a>, <a href="#Page_108">108</a>, <a href="#Page_113">113</a>, <a href="#Page_119">119</a>, <a href="#Page_120">120</a>, <a href="#Page_211">211</a><br />
+<br />
+Bird-reptile, <a href="#Page_188">188</a><br />
+<br />
+Bird wing, <a href="#Page_128">128</a>, <a href="#Page_130">130</a><br />
+<br />
+Birds in flight, <a href="#Page_22">22</a>;<br />
+<span style="margin-left: 1em;">with teeth, <a href="#Page_76">76</a></span><br />
+<br />
+Black-headed bunting, <a href="#Page_47">47</a><br />
+<br />
+Blainville, D. de, <a href="#Page_30">30</a>, <a href="#Page_193">193</a><br />
+<br />
+Blood, temperature of, <a href="#Page_56">56</a><br />
+<br />
+Bohemia, <a href="#Page_34">34</a><br />
+<br />
+Bonaparte, Prince Charles, <a href="#Page_30">30</a><br />
+<br />
+Bones of birds, variation in, <a href="#Page_41">41</a><br />
+<br />
+&mdash; of reptiles, variation in, <a href="#Page_42">42</a><br />
+<br />
+&mdash; about the brain, <a href="#Page_69">69</a><br />
+<br />
+&mdash; in the back, <a href="#Page_84">84</a><br />
+<br />
+Bone texture, <a href="#Page_59">59</a>, <a href="#Page_209">209</a><br />
+<br />
+Bonn Museum, <a href="#Page_32">32</a>, <a href="#Page_85">85</a>, <a href="#Page_156">156</a><br />
+<br />
+Brain and breathing organs, <a href="#Page_55">55</a><br />
+<br />
+Brain cavity, in birds and reptiles, <a href="#Page_52">52</a>;<br />
+<span style="margin-left: 1em;">in mammals, <a href="#Page_221">221</a>, <a href="#Page_226">226</a>;</span><br />
+<span style="margin-left: 1em;">in Solenhofen pterodactyles, <a href="#Page_54">54</a>, <a href="#Page_220">220</a></span><br />
+<br />
+Brazil, <a href="#Page_34">34</a><br />
+<br />
+Breathing organs, <a href="#Page_8">8</a><br />
+<br />
+Bridgewater Treatise, <a href="#Page_143">143</a><br />
+<br />
+British Museum, <a href="#Page_133">133</a>, <a href="#Page_183">183</a><br />
+<br />
+Brixton, Isle of Wight, <a href="#Page_55">55</a>, <a href="#Page_174">174</a><br />
+<br />
+Buckland, Dean, <a href="#Page_143">143</a>, <a href="#Page_148">148</a>, <a href="#Page_231">231</a><br />
+<br />
+Burrowing limb, <a href="#Page_38">38</a><br />
+<span class='pagenum'><a name="Page_234" id="Page_234">[Pg 234]</a></span><br />
+<br />
+<b>C</b><br />
+<br />
+Cactus, <a href="#Page_227">227</a><br />
+<br />
+Calamospondylus, <a href="#Page_203">203</a><br />
+<br />
+Cambridge Greensand, <a href="#Page_33">33</a>, <a href="#Page_89">89</a>, <a href="#Page_176">176</a><br />
+<br />
+&mdash; Museum, <a href="#Page_177">177</a><br />
+<br />
+Camel, <a href="#Page_83">83</a><br />
+<br />
+Campylognathus, <a href="#Page_68">68</a>, <a href="#Page_71">71</a>, <a href="#Page_135">135</a>;<br />
+<span style="margin-left: 1em;">size of, <a href="#Page_149">149</a></span><br />
+<br />
+Canary, <a href="#Page_47">47</a><br />
+<br />
+Carnivorous dinosaurs, <a href="#Page_129">129</a><br />
+<br />
+Carpus, <a href="#Page_122">122</a><br />
+<br />
+Caudal fin, <a href="#Page_91">91</a>, <a href="#Page_161">161</a><br />
+<br />
+&mdash; vertebr&aelig;, <a href="#Page_89">89</a>, <a href="#Page_92">92</a>, <a href="#Page_203">203</a><br />
+<br />
+Ceratodus, <a href="#Page_4">4</a>, <a href="#Page_5">5</a>, <a href="#Page_9">9</a>, <a href="#Page_17">17</a><br />
+<br />
+Ceratosaurus, <a href="#Page_203">203</a>, <a href="#Page_204">204</a><br />
+<br />
+Cervical rib, <a href="#Page_81">81</a><br />
+<br />
+Cetacea, <a href="#Page_40">40</a><br />
+<br />
+Cetiosaurus, <a href="#Page_198">198</a>, <a href="#Page_203">203</a><br />
+<br />
+Chalinolobus, <a href="#Page_25">25</a><br />
+<br />
+Chalk, pterodactyles in, <a href="#Page_136">136</a>;<br />
+<span style="margin-left: 1em;">of Kansas, <a href="#Page_103">103</a>, <a href="#Page_132">132</a></span><br />
+<br />
+Chameleon, <a href="#Page_17">17</a>, <a href="#Page_51">51</a>, <a href="#Page_70">70</a>;<br />
+<span style="margin-left: 1em;">scapula, <a href="#Page_112">112</a>;</span><br />
+<span style="margin-left: 1em;">sternum, <a href="#Page_107">107</a></span><br />
+<br />
+Chameleonoidea, <a href="#Page_191">191</a><br />
+<br />
+Cheek bones, <a href="#Page_178">178</a><br />
+<br />
+Chelonia, <a href="#Page_86">86</a>, <a href="#Page_112">112</a>, <a href="#Page_193">193</a><br />
+<br />
+Chesterton, <a href="#Page_177">177</a><br />
+<br />
+Chlamydosaurus, <a href="#Page_21">21</a><br />
+<br />
+<i>Chrysochloris capensis</i>, <a href="#Page_121">121</a><br />
+<br />
+Classification, <a href="#Page_192">192</a>;<br />
+<span style="margin-left: 1em;">on pelvis characters, <a href="#Page_195">195</a>;</span><br />
+<span style="margin-left: 1em;">of dinosaurs, <a href="#Page_198">198</a></span><br />
+<br />
+Clavicles, <a href="#Page_111">111</a>, <a href="#Page_112">112</a><br />
+<br />
+Claw, <a href="#Page_105">105</a>, <a href="#Page_116">116</a>, <a href="#Page_183">183</a>, <a href="#Page_208">208</a><br />
+<br />
+C&#339;lurus, <a href="#Page_203">203</a>, <a href="#Page_209">209</a><br />
+<br />
+Coldham Common, <a href="#Page_177">177</a><br />
+<br />
+Collar bone, <a href="#Page_111">111</a><br />
+<br />
+Collini, <a href="#Page_27">27</a><br />
+<br />
+Comparison with dinosaurs, <a href="#Page_198">198</a>;<br />
+<span style="margin-left: 1em;">of pelvis, <a href="#Page_204">204</a>, <a href="#Page_206">206</a>;</span><br />
+<span style="margin-left: 1em;">of skulls, <a href="#Page_192">192</a>, <a href="#Page_199">199</a>, <a href="#Page_201">201</a></span><br />
+<br />
+Cope, Professor, <a href="#Page_31">31</a>, <a href="#Page_34">34</a><br />
+<br />
+Coracoid, <a href="#Page_109">109</a>, <a href="#Page_112">112</a>, <a href="#Page_113">113</a><br />
+<br />
+Cordylomorpha, <a href="#Page_191">191</a><br />
+<br />
+Cormorant, <a href="#Page_70">70</a>, <a href="#Page_174">174</a>;<br />
+<span style="margin-left: 1em;">sternum, <a href="#Page_108">108</a></span><br />
+<br />
+Corpora quadrigemina, <a href="#Page_221">221</a><br />
+<br />
+Crisp, Dr., on pneumatic skeleton, <a href="#Page_47">47</a><br />
+<br />
+Crocodile, characters of, <a href="#Page_217">217</a>;<br />
+<span style="margin-left: 1em;">heart, <a href="#Page_56">56</a>;</span><br />
+<span style="margin-left: 1em;">lung, <a href="#Page_9">9</a>;</span><br />
+<span style="margin-left: 1em;">shoulder-girdle, <a href="#Page_111">111</a>;</span><br />
+<span style="margin-left: 1em;">skull, <a href="#Page_46">46</a>;</span><br />
+<span style="margin-left: 1em;">vertebr&aelig;, <a href="#Page_79">79</a></span><br />
+<br />
+Crocodilia, <a href="#Page_190">190</a><br />
+<br />
+Curlew, <a href="#Page_68">68</a><br />
+<br />
+Cuvier, <a href="#Page_1">1</a>, <a href="#Page_27">27</a>, <a href="#Page_28">28</a>, <a href="#Page_54">54</a>, <a href="#Page_76">76</a>, <a href="#Page_77">77</a>, <a href="#Page_130">130</a>, <a href="#Page_231">231</a><br />
+<br />
+Cycnorhamphus, <a href="#Page_70">70</a>, <a href="#Page_94">94</a>, <a href="#Page_171">171</a>, <a href="#Page_173">173</a>, <a href="#Page_204">204</a><br />
+<br />
+<i>Cycnorhamphus Fraasii</i>, <a href="#Page_80">80</a>, <a href="#Page_96">96</a>, <a href="#Page_169">169</a><br />
+<br />
+&mdash; <i>suevicus</i>, <a href="#Page_169">169</a>, <a href="#Page_170">170</a><br />
+<br />
+Cypselus, <a href="#Page_42">42</a><br />
+<br />
+<br />
+<b>D</b><br />
+<br />
+<i>Dacelo gigantea</i>, <a href="#Page_63">63</a><br />
+<br />
+Darwin, <a href="#Page_3">3</a><br />
+<br />
+Davy, Dr. John, <a href="#Page_142">142</a><br />
+<br />
+Deuterosaurus, <a href="#Page_97">97</a><br />
+<br />
+Dicynodon, <a href="#Page_200">200</a><br />
+<br />
+<i>Dicynodon lacerticeps</i>, <a href="#Page_71">71</a><br />
+<br />
+Digits, of ostrich, <a href="#Page_23">23</a>;<br />
+<span style="margin-left: 1em;">of pterodactyle, <a href="#Page_128">128</a></span><br />
+<br />
+Digits with claws, <a href="#Page_130">130</a>;<br />
+<span style="margin-left: 1em;">foot bones in, <a href="#Page_105">105</a></span><br />
+<br />
+Dimorphodon, <a href="#Page_63">63</a>, <a href="#Page_64">64</a>, <a href="#Page_66">66</a>, <a href="#Page_67">67</a>, <a href="#Page_73">73</a>, <a href="#Page_74">74</a>, <a href="#Page_83">83</a>, <a href="#Page_90">90</a>, <a href="#Page_102">102</a>, <a href="#Page_113">113</a>, <a href="#Page_143">143</a>, <a href="#Page_192">192</a>, <a href="#Page_194">194</a>, <a href="#Page_199">199</a>, <a href="#Page_201">201</a>, <a href="#Page_206">206</a><br />
+<br />
+Dinosauria, <a href="#Page_6">6</a>, <a href="#Page_77">77</a>, <a href="#Page_84">84</a>, <a href="#Page_87">87</a>, <a href="#Page_95">95</a>, <a href="#Page_129">129</a>, <a href="#Page_144">144</a>, <a href="#Page_198">198</a>, <a href="#Page_209">209</a><br />
+<br />
+Dinosaurs from Lias, <a href="#Page_135">135</a>, <a href="#Page_192">192</a>;<br />
+<span style="margin-left: 1em;">from Elgin, <a href="#Page_201">201</a>, <a href="#Page_207">207</a>;</span><br />
+<span style="margin-left: 1em;">Stuttgart, <a href="#Page_202">202</a>;</span><br />
+<span style="margin-left: 1em;">Trias dinosaurs, <a href="#Page_199">199</a>, <a href="#Page_200">200</a></span><br />
+<br />
+Diopecephalus, <a href="#Page_168">168</a><br />
+<br />
+Diving birds, <a href="#Page_23">23</a>, <a href="#Page_83">83</a>, <a href="#Page_102">102</a><br />
+<br />
+Dolichosauria, <a href="#Page_191">191</a><br />
+<br />
+Dolphin, <a href="#Page_107">107</a><br />
+<br />
+Doratorhynchus, <a href="#Page_173">173</a><br />
+<br />
+Dorygnathus, <a href="#Page_74">74</a>, <a href="#Page_148">148</a><br />
+<br />
+Dragons, <a href="#Page_3">3</a>, <a href="#Page_15">15</a>, <a href="#Page_17">17</a><br />
+<br />
+Drumstick bone, <a href="#Page_103">103</a>, <a href="#Page_195">195</a><br />
+<br />
+Duck, <a href="#Page_22">22</a>, <a href="#Page_83">83</a><br />
+<br />
+<br />
+<b>E</b><br />
+<br />
+Echidna, <a href="#Page_75">75</a>, <a href="#Page_76">76</a>, <a href="#Page_95">95</a>, <a href="#Page_100">100</a><br />
+<br />
+Edentata, <a href="#Page_185">185</a><br />
+<br />
+Edentulous beak, <a href="#Page_153">153</a><br />
+<br />
+Eichst&auml;dt, <a href="#Page_32">32</a><br />
+<br />
+Elephant, head of, <a href="#Page_46">46</a><br />
+<br />
+Enumeration of characters, <a href="#Page_223">223</a>, <a href="#Page_225">225</a><br />
+<br />
+Ephesus, winged figure, <a href="#Page_16">16</a><br />
+<br />
+Epiphysis to first phalange, <a href="#Page_123">123</a><br />
+<br />
+Exoc&#339;tus, <a href="#Page_18">18</a><br />
+<span class='pagenum'><a name="Page_235" id="Page_235">[Pg 235]</a></span><br />
+Extinctions, <a href="#Page_129">129</a><br />
+<br />
+Eye hole, <a href="#Page_144">144</a>;<br />
+<span style="margin-left: 1em;">sclerotic bones in, <a href="#Page_65">65</a></span><br />
+<br />
+<br />
+<b>F</b><br />
+<br />
+Farren, William, <a href="#Page_34">34</a><br />
+<br />
+Femur, <a href="#Page_100">100</a><br />
+<br />
+Fibula, <a href="#Page_102">102</a>, <a href="#Page_183">183</a>, <a href="#Page_206">206</a><br />
+<br />
+Fifth outer digit, <a href="#Page_132">132</a>;<br />
+<span style="margin-left: 1em;">in foot, <a href="#Page_145">145</a></span><br />
+<br />
+Figure from temple at Ephesus, <a href="#Page_16">16</a><br />
+<br />
+First phalange, <a href="#Page_151">151</a><br />
+<br />
+Fish-eating crocodile, <a href="#Page_137">137</a><br />
+<br />
+Flight, organs of, <a href="#Page_17">17</a>;<br />
+<span style="margin-left: 1em;">in bats, <a href="#Page_25">25</a></span><br />
+<br />
+Flying limb, <a href="#Page_38">38</a><br />
+<br />
+Flying fishes, <a href="#Page_18">18</a>, <a href="#Page_57">57</a>;<br />
+<span style="margin-left: 1em;">foxes, <a href="#Page_26">26</a>;</span><br />
+<span style="margin-left: 1em;">frogs, <a href="#Page_19">19</a>, <a href="#Page_197">197</a>;</span><br />
+<span style="margin-left: 1em;">gecko, <a href="#Page_21">21</a>, <a href="#Page_24">24</a>;</span><br />
+<span style="margin-left: 1em;">lizards, <a href="#Page_20">20</a>;</span><br />
+<span style="margin-left: 1em;">reptiles, <a href="#Page_37">37</a>, <a href="#Page_46">46</a>;</span><br />
+<span style="margin-left: 1em;">squirrel, <a href="#Page_24">24</a></span><br />
+<br />
+Foot, <a href="#Page_104">104</a>;<br />
+<span style="margin-left: 1em;">digits in, <a href="#Page_105">105</a>, <a href="#Page_146">146</a></span><br />
+<br />
+Fore leg, <a href="#Page_102">102</a>, <a href="#Page_206">206</a><br />
+<br />
+&mdash; limb, <a href="#Page_38">38</a>, <a href="#Page_107">107</a>, <a href="#Page_116">116</a>, <a href="#Page_120">120</a><br />
+<br />
+Four claws, <a href="#Page_147">147</a><br />
+<br />
+Fox, Rev. W., <a href="#Page_55">55</a>, <a href="#Page_174">174</a><br />
+<br />
+Fraas, Professor Oscar, <a href="#Page_172">172</a>, <a href="#Page_231">231</a><br />
+<br />
+Frigate bird, vertebr&aelig; of, <a href="#Page_86">86</a>, <a href="#Page_174">174</a><br />
+<br />
+Frog, lungs of, <a href="#Page_8">8</a><br />
+<br />
+Furculum, <a href="#Page_114">114</a><br />
+<br />
+<br />
+<b>G</b><br />
+<br />
+Gaudry, Professor A., <a href="#Page_31">31</a><br />
+<br />
+Gavial, <a href="#Page_136">136</a><br />
+<br />
+Gecko, <a href="#Page_21">21</a>, <a href="#Page_23">23</a><br />
+<br />
+Genera, comparison of, <a href="#Page_192">192</a><br />
+<br />
+Geological distribution, <a href="#Page_186">186</a><br />
+<br />
+Gills, <a href="#Page_4">4</a><br />
+<br />
+Giraffe, <a href="#Page_38">38</a>, <a href="#Page_39">39</a><br />
+<br />
+Glossy starling, <a href="#Page_47">47</a><br />
+<br />
+Golden eagle, <a href="#Page_120">120</a><br />
+<br />
+&mdash; mole, <a href="#Page_121">121</a><br />
+<br />
+Goldfuss, <a href="#Page_30">30</a>, <a href="#Page_231">231</a><br />
+<br />
+Granchester, <a href="#Page_177">177</a><br />
+<br />
+Great ant-eater, <a href="#Page_40">40</a>, <a href="#Page_185">185</a><br />
+<br />
+Guillemot, <a href="#Page_102">102</a><br />
+<br />
+Gull, <a href="#Page_22">22</a><br />
+<br />
+<br />
+<b>H</b><br />
+<br />
+Haarlem, Teyler Museum at, <a href="#Page_32">32</a><br />
+<br />
+Habits, probable, <a href="#Page_134">134</a>, <a href="#Page_176">176</a>, <a href="#Page_198">198</a><br />
+<br />
+Hairless skins, <a href="#Page_141">141</a><br />
+<br />
+Hand in mammals, <a href="#Page_38">38</a><br />
+<br />
+Harston, <a href="#Page_177">177</a><br />
+<br />
+Haslingfield, <a href="#Page_177">177</a><br />
+<br />
+Hastings, <a href="#Page_174">174</a><br />
+<br />
+Hatteria lung, <a href="#Page_9">9</a>, <a href="#Page_27">27</a>;<br />
+<span style="margin-left: 1em;">brain, <a href="#Page_53">53</a>;</span><br />
+<span style="margin-left: 1em;">skull, <a href="#Page_70">70</a>, <a href="#Page_77">77</a>;</span><br />
+<span style="margin-left: 1em;">ribs, <a href="#Page_86">86</a>;</span><br />
+<span style="margin-left: 1em;">a reptile type, <a href="#Page_13">13</a></span><br />
+<br />
+Head, characters of, <a href="#Page_76">76</a><br />
+<br />
+Heidelberg Museum, <a href="#Page_32">32</a>, <a href="#Page_54">54</a>, <a href="#Page_159">159</a><br />
+<br />
+Herpetomorpha, <a href="#Page_191">191</a><br />
+<br />
+Heron, <a href="#Page_65">65</a>, <a href="#Page_174">174</a><br />
+<br />
+Hesperornis, <a href="#Page_76">76</a><br />
+<br />
+Hind foot, <a href="#Page_104">104</a>, <a href="#Page_135">135</a><br />
+<br />
+&mdash; limb, <a href="#Page_93">93</a>, <a href="#Page_99">99</a>, <a href="#Page_159">159</a>, <a href="#Page_206">206</a><br />
+<br />
+Hip-girdle in whale tribe, <a href="#Page_39">39</a>, <a href="#Page_159">159</a><br />
+<br />
+Hom&#339;osauria, <a href="#Page_191">191</a><br />
+<br />
+Horningsea, <a href="#Page_177">177</a><br />
+<br />
+Horse, metacarpus of, <a href="#Page_127">127</a>;<br />
+<span style="margin-left: 1em;">vertebr&aelig; of, <a href="#Page_79">79</a></span><br />
+<br />
+Humerus, <a href="#Page_46">46</a>, <a href="#Page_117">117</a>, <a href="#Page_217">217</a><br />
+<br />
+Huxley, Professor, <a href="#Page_31">31</a>, <a href="#Page_89">89</a>, <a href="#Page_154">154</a>, <a href="#Page_188">188</a><br />
+<br />
+Hyo-mandibular arch, <a href="#Page_13">13</a><br />
+<br />
+Hypothesis of descent, <a href="#Page_226">226</a><br />
+<br />
+Hyrax, <a href="#Page_101">101</a><br />
+<br />
+<br />
+<b>I</b><br />
+<br />
+Ichthyornis, <a href="#Page_76">76</a><br />
+<br />
+Ichthyosaurus, <a href="#Page_6">6</a>, <a href="#Page_191">191</a><br />
+<br />
+Iguanodon, <a href="#Page_209">209</a>;<br />
+<span style="margin-left: 1em;">pelvis, <a href="#Page_206">206</a></span><br />
+<br />
+Ilium, <a href="#Page_93">93</a>, <a href="#Page_95">95</a>, <a href="#Page_96">96</a>, <a href="#Page_98">98</a>, <a href="#Page_204">204</a><br />
+<br />
+Instep, <a href="#Page_105">105</a>, <a href="#Page_207">207</a><br />
+<br />
+Inherited characters, <a href="#Page_217">217</a><br />
+<br />
+Interclavicle, <a href="#Page_111">111</a><br />
+<br />
+Ischium, <a href="#Page_93">93</a>, <a href="#Page_96">96</a>, <a href="#Page_203">203</a>, <a href="#Page_204">204</a><br />
+<br />
+Isle of Wight, <a href="#Page_174">174</a><br />
+<br />
+<br />
+<b>J</b><br />
+<br />
+Jaw, in birds, <a href="#Page_12">12</a>;<br />
+<span style="margin-left: 1em;">in fishes, <a href="#Page_13">13</a>;</span><br />
+<span style="margin-left: 1em;">in mammals, <a href="#Page_12">12</a>;</span><br />
+<span style="margin-left: 1em;">in reptiles, <a href="#Page_13">13</a>;</span><br />
+<span style="margin-left: 1em;">in pterodactyles, <a href="#Page_63">63</a>;</span><br />
+<span style="margin-left: 1em;">suspension of, <a href="#Page_11">11</a>, <a href="#Page_74">74</a>, <a href="#Page_76">76</a></span><br />
+<br />
+&mdash; lower, <a href="#Page_75">75</a><br />
+<br />
+<br />
+<b>K</b><br />
+<br />
+Kansas, Chalk of, <a href="#Page_72">72</a>, <a href="#Page_103">103</a>, <a href="#Page_115">115</a>;<br />
+<span style="margin-left: 1em;">University Museum of, <a href="#Page_181">181</a></span><br />
+<br />
+Kelheim, <a href="#Page_32">32</a><br />
+<br />
+Keuper, <a href="#Page_33">33</a><br />
+<br />
+Kimeridge Clay, <a href="#Page_132">132</a><br />
+<br />
+Kingfisher, <a href="#Page_63">63</a><br />
+<br />
+Kiwi, <a href="#Page_23">23</a><br />
+<span class='pagenum'><a name="Page_236" id="Page_236">[Pg 236]</a></span><br />
+<br />
+<b>L</b><br />
+<br />
+Labyrinthodontia, <a href="#Page_191">191</a><br />
+<br />
+Lachrymal bones, <a href="#Page_67">67</a><br />
+<br />
+Laramie rocks, <a href="#Page_34">34</a><br />
+<br />
+Largest ornithosaur, <a href="#Page_133">133</a><br />
+<br />
+Lateral vacuities in skull, <a href="#Page_147">147</a><br />
+<br />
+Lawrence in Kansas, <a href="#Page_181">181</a><br />
+<br />
+Lengths of bones, <a href="#Page_146">146</a><br />
+<br />
+Lepidosiren, <a href="#Page_17">17</a><br />
+<br />
+Lias, <a href="#Page_33">33</a><br />
+<br />
+Lithographic Slate, <a href="#Page_35">35</a>, <a href="#Page_156">156</a><br />
+<br />
+Lizards, <a href="#Page_20">20</a>, <a href="#Page_21">21</a>, <a href="#Page_27">27</a>, <a href="#Page_123">123</a><br />
+<br />
+Llama, neck of, <a href="#Page_79">79</a>, <a href="#Page_83">83</a><br />
+<br />
+Loach, swim bladder of, <a href="#Page_52">52</a><br />
+<br />
+Lower jaw, <a href="#Page_12">12</a>, <a href="#Page_74">74</a>, <a href="#Page_76">76</a>, <a href="#Page_149">149</a><br />
+<br />
+Lumbar vertebr&aelig;, <a href="#Page_89">89</a><br />
+<br />
+Lungs, <a href="#Page_47">47</a>;<br />
+<span style="margin-left: 1em;">in apteryx, <a href="#Page_48">48</a>;</span><br />
+<span style="margin-left: 1em;">in chameleon, <a href="#Page_51">51</a>;</span><br />
+<span style="margin-left: 1em;">in ostrich, <a href="#Page_49">49</a>;</span><br />
+<span style="margin-left: 1em;">in reptiles, <a href="#Page_8">8</a>, <a href="#Page_9">9</a>, <a href="#Page_51">51</a></span><br />
+<br />
+Lydekker, R., <a href="#Page_160">160</a>, <a href="#Page_169">169</a>, <a href="#Page_231">231</a><br />
+<br />
+Lyme Regis, <a href="#Page_33">33</a><br />
+<br />
+<br />
+<b>M</b><br />
+<br />
+Macrocercus, palate of, <a href="#Page_71">71</a><br />
+<br />
+Malar bone, <a href="#Page_67">67</a><br />
+<br />
+Mallard, <a href="#Page_22">22</a><br />
+<br />
+Mammal, <a href="#Page_8">8</a>, <a href="#Page_12">12</a>, <a href="#Page_24">24</a>, <a href="#Page_79">79</a>, <a href="#Page_53">53</a>, <a href="#Page_95">95</a><br />
+<br />
+Mammalia, <a href="#Page_38">38</a>, <a href="#Page_141">141</a><br />
+<br />
+Mammalian characters, <a href="#Page_12">12</a>, <a href="#Page_220">220</a><br />
+<br />
+Mammoth, <a href="#Page_141">141</a><br />
+<br />
+Manis, <a href="#Page_40">40</a>, <a href="#Page_57">57</a>, <a href="#Page_142">142</a><br />
+<br />
+Manubrium of sternum, <a href="#Page_108">108</a>, <a href="#Page_109">109</a>, <a href="#Page_183">183</a><br />
+<br />
+Marrow bones in a bird, <a href="#Page_134">134</a><br />
+<br />
+Marsh, Professor O. C., <a href="#Page_31">31</a>, <a href="#Page_72">72</a>, <a href="#Page_90">90</a>, <a href="#Page_115">115</a>, <a href="#Page_121">121</a>, <a href="#Page_131">131</a>, <a href="#Page_140">140</a>, <a href="#Page_160">160</a>, <a href="#Page_165">165</a>, <a href="#Page_180">180</a>, <a href="#Page_181">181</a>, <a href="#Page_210">210</a>, <a href="#Page_231">231</a><br />
+<br />
+Marsupial, <a href="#Page_70">70</a>, <a href="#Page_94">94</a>, <a href="#Page_99">99</a><br />
+<br />
+Megalosaurus, <a href="#Page_129">129</a>, <a href="#Page_198">198</a><br />
+<br />
+Merganser, <a href="#Page_108">108</a><br />
+<br />
+Merry-thought, <a href="#Page_114">114</a><br />
+<br />
+Metacarpus, <a href="#Page_116">116</a>, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>, <a href="#Page_128">128</a>, <a href="#Page_130">130</a><br />
+<br />
+Metatarsal bones, <a href="#Page_104">104</a>, <a href="#Page_207">207</a>, <a href="#Page_208">208</a><br />
+<br />
+Meyer, Hermann von, <a href="#Page_31">31</a>, <a href="#Page_45">45</a>, <a href="#Page_46">46</a>, <a href="#Page_85">85</a>, <a href="#Page_105">105</a>, <a href="#Page_108">108</a>, <a href="#Page_121">121</a>, <a href="#Page_160">160</a>, <a href="#Page_192">192</a>, <a href="#Page_231">231</a><br />
+<br />
+Moa of New Zealand, <a href="#Page_35">35</a><br />
+<br />
+Mole, humerus, <a href="#Page_38">38</a>;<br />
+<span style="margin-left: 1em;">sternum, <a href="#Page_107">107</a></span><br />
+<br />
+Monotremes, <a href="#Page_70">70</a>, <a href="#Page_94">94</a>, <a href="#Page_111">111</a>, <a href="#Page_121">121</a>, <a href="#Page_185">185</a>, <a href="#Page_218">218</a><br />
+<br />
+Mososaurus, <a href="#Page_77">77</a><br />
+<br />
+Movement of the leg, <a href="#Page_101">101</a><br />
+<br />
+Mugger, <a href="#Page_137">137</a><br />
+<br />
+Munich Museum, <a href="#Page_32">32</a>, <a href="#Page_159">159</a><br />
+<br />
+Munster, von, <a href="#Page_231">231</a><br />
+<br />
+Muschelkalk, <a href="#Page_184">184</a><br />
+<br />
+Museum, <a href="#Page_32">32</a>, <a href="#Page_156">156</a>, <a href="#Page_231">231</a>, <a href="#Page_159">159</a>;<br />
+<span style="margin-left: 1em;">Natural History, <a href="#Page_133">133</a>, <a href="#Page_231">231</a></span><br />
+<br />
+Myrmecophaga, <a href="#Page_185">185</a><br />
+<br />
+<br />
+<b>N</b><br />
+<br />
+Names of genera, <a href="#Page_183">183</a><br />
+<br />
+Natural History Museum, <a href="#Page_38">38</a>, <a href="#Page_231">231</a><br />
+<br />
+Neck, <a href="#Page_79">79</a>;<br />
+<span style="margin-left: 1em;">in Dimorphodon, <a href="#Page_145">145</a>;</span><br />
+<span style="margin-left: 1em;">in Giraffe, <a href="#Page_39">39</a>;</span><br />
+<span style="margin-left: 1em;">in Llama, <a href="#Page_79">79</a>;</span><br />
+<span style="margin-left: 1em;">in Pterodactyles, <a href="#Page_80">80</a>;</span><br />
+<span style="margin-left: 1em;">in Whales, <a href="#Page_39">39</a></span><br />
+<br />
+Newton, E. T., <a href="#Page_55">55</a>, <a href="#Page_70">70</a>, <a href="#Page_158">158</a>, <a href="#Page_160">160</a>, <a href="#Page_201">201</a>, <a href="#Page_232">232</a><br />
+<br />
+New Zealand Bat, <a href="#Page_25">25</a><br />
+<br />
+&mdash; &mdash; Hatteria, <a href="#Page_68">68</a><br />
+<br />
+Niobrara rock, <a href="#Page_183">183</a><br />
+<br />
+Nostril, bones round the, <a href="#Page_62">62</a>;<br />
+<span style="margin-left: 1em;">small, <a href="#Page_147">147</a></span><br />
+<br />
+Notarium, <a href="#Page_87">87</a>, <a href="#Page_115">115</a><br />
+<br />
+Nothosauria, <a href="#Page_192">192</a><br />
+<br />
+Nusplingen, <a href="#Page_32">32</a><br />
+<br />
+Nyctodactylus, <a href="#Page_115">115</a>, <a href="#Page_180">180</a><br />
+<br />
+<br />
+<b>O</b><br />
+<br />
+Obliteration of characters, <a href="#Page_216">216</a><br />
+<br />
+Opercular bones, <a href="#Page_13">13</a><br />
+<br />
+Ophidia, <a href="#Page_52">52</a>, <a href="#Page_191">191</a><br />
+<br />
+Optic lobes, <a href="#Page_53">53</a>, <a href="#Page_221">221</a><br />
+<br />
+Organs of flight, <a href="#Page_17">17</a><br />
+<br />
+Ornithischia, <a href="#Page_190">190</a>, <a href="#Page_198">198</a><br />
+<br />
+Ornithocephalus, <a href="#Page_166">166</a><br />
+<br />
+Ornithocheirus, atlas and axis, <a href="#Page_81">81</a>;<br />
+<span style="margin-left: 1em;">brain, <a href="#Page_55">55</a>, <a href="#Page_69">69</a>;</span><br />
+<span style="margin-left: 1em;">carpus, <a href="#Page_124">124</a>;</span><br />
+<span style="margin-left: 1em;">cervical vertebra, <a href="#Page_83">83</a>, <a href="#Page_179">179</a>;</span><br />
+<span style="margin-left: 1em;">claw phalange, <a href="#Page_129">129</a>;</span><br />
+<span style="margin-left: 1em;">coracoid, <a href="#Page_109">109</a>;</span><br />
+<span style="margin-left: 1em;">femur, <a href="#Page_100">100</a>;</span><br />
+<span style="margin-left: 1em;">pelvis, <a href="#Page_98">98</a>;</span><br />
+<span style="margin-left: 1em;">pubic bones, <a href="#Page_194">194</a>;</span><br />
+<span style="margin-left: 1em;">sternum, <a href="#Page_109">109</a>;</span><br />
+<span style="margin-left: 1em;">shoulder-girdle, <a href="#Page_115">115</a>;</span><br />
+<span style="margin-left: 1em;">remains, <a href="#Page_176">176</a>;</span><br />
+<span style="margin-left: 1em;">teeth, <a href="#Page_74">74</a>, <a href="#Page_76">76</a>;</span><br />
+<span style="margin-left: 1em;">absence of teeth, <a href="#Page_138">138</a></span><br />
+<br />
+<i>Ornithocheirus mach&aelig;rorhynchus</i>, <a href="#Page_139">139</a>;<br />
+<span style="margin-left: 1em;"><i>microdon</i>, <a href="#Page_139">139</a></span><br />
+<span class='pagenum'><a name="Page_237" id="Page_237">[Pg 237]</a></span><br />
+Ornithocheiroidea, <a href="#Page_193">193</a><br />
+<br />
+Ornithodesmus, neck bones, <a href="#Page_173">173</a>, <a href="#Page_175">175</a>;<br />
+<span style="margin-left: 1em;">coracoid, <a href="#Page_109">109</a>, <a href="#Page_116">116</a>;</span><br />
+<span style="margin-left: 1em;">dorsal vertebr&aelig;, <a href="#Page_86">86</a>;</span><br />
+<span style="margin-left: 1em;">remains of <i>O. latidens</i>, <a href="#Page_173">173</a>;</span><br />
+<span style="margin-left: 1em;"><i>O. sagittirostris</i>, <a href="#Page_175">175</a></span><br />
+<br />
+Ornithomorpha, <a href="#Page_189">189</a><br />
+<br />
+Ornithorhynchus, <a href="#Page_40">40</a>, <a href="#Page_53">53</a>, <a href="#Page_95">95</a>, <a href="#Page_117">117</a><br />
+<br />
+Ornithosauria, <a href="#Page_30">30</a>, <a href="#Page_31">31</a>, <a href="#Page_50">50</a>, <a href="#Page_52">52</a>, <a href="#Page_58">58</a>, <a href="#Page_72">72</a>, <a href="#Page_89">89</a>, <a href="#Page_95">95</a>, <a href="#Page_104">104</a>, <a href="#Page_108">108</a>, <a href="#Page_125">125</a>, <a href="#Page_132">132</a>, <a href="#Page_133">133</a>, <a href="#Page_143">143</a>, <a href="#Page_187">187</a>, <a href="#Page_190">190</a>, <a href="#Page_192">192</a>, <a href="#Page_216">216</a><br />
+<br />
+Ornithostoma, <a href="#Page_66">66</a>, <a href="#Page_69">69</a>, <a href="#Page_72">72</a>, <a href="#Page_180">180</a>;<br />
+<span style="margin-left: 1em;">lower jaw, <a href="#Page_75">75</a>, <a href="#Page_76">76</a>;</span><br />
+<span style="margin-left: 1em;">pelvis, <a href="#Page_98">98</a>;</span><br />
+<span style="margin-left: 1em;">sternum, <a href="#Page_110">110</a>;</span><br />
+<span style="margin-left: 1em;">phalange, <a href="#Page_122">122</a>;</span><br />
+<span style="margin-left: 1em;">size, <a href="#Page_133">133</a>;</span><br />
+<span style="margin-left: 1em;">skull, <a href="#Page_181">181</a>, <a href="#Page_182">182</a></span><br />
+<br />
+Ornithosuchus, <a href="#Page_201">201</a><br />
+<br />
+Orycteropus, <a href="#Page_96">96</a><br />
+<br />
+<i>Ossa innominata</i>, <a href="#Page_93">93</a><br />
+<br />
+Ossified ligaments, <a href="#Page_150">150</a><br />
+<br />
+Ostrich, <a href="#Page_23">23</a>, <a href="#Page_45">45</a>, <a href="#Page_49">49</a>, <a href="#Page_113">113</a>, <a href="#Page_129">129</a><br />
+<br />
+Owen, Sir R., <a href="#Page_31">31</a>, <a href="#Page_36">36</a>, <a href="#Page_46">46</a>, <a href="#Page_48">48</a>, <a href="#Page_110">110</a>, <a href="#Page_117">117</a>, <a href="#Page_143">143</a>, <a href="#Page_172">172</a>, <a href="#Page_176">176</a>, <a href="#Page_180">180</a>, <a href="#Page_231">231</a><br />
+<br />
+Owl, <a href="#Page_46">46</a>, <a href="#Page_53">53</a><br />
+<br />
+Oxford Clay, <a href="#Page_33">33</a>, <a href="#Page_156">156</a><br />
+<br />
+&mdash; University Museum, <a href="#Page_154">154</a><br />
+<br />
+Ox, vertebra of, <a href="#Page_79">79</a>;<br />
+<span style="margin-left: 1em;">metacarpus, <a href="#Page_127">127</a></span><br />
+<br />
+<br />
+<b>P</b><br />
+<br />
+Palate, bones of, <a href="#Page_71">71</a><br />
+<br />
+Pangolin, <a href="#Page_142">142</a><br />
+<br />
+Pappenheim, <a href="#Page_32">32</a><br />
+<br />
+Parallel groups, <a href="#Page_215">215</a><br />
+<br />
+Parrot, <a href="#Page_71">71</a><br />
+<br />
+Patagial membranes, <a href="#Page_227">227</a><br />
+<br />
+Pelican, <a href="#Page_174">174</a><br />
+<br />
+Pelvis, <a href="#Page_88">88</a>, <a href="#Page_94">94-98</a>, <a href="#Page_151">151</a>, <a href="#Page_195">195</a>, <a href="#Page_202">202</a>, <a href="#Page_204">204</a>, <a href="#Page_206">206</a><br />
+<br />
+Penguin, <a href="#Page_41">41</a>, <a href="#Page_42">42</a>, <a href="#Page_104">104</a>, <a href="#Page_176">176</a><br />
+<br />
+Periophthalmus, <a href="#Page_17">17</a><br />
+<br />
+Peterborough, bones from, <a href="#Page_113">113</a>, <a href="#Page_156">156</a><br />
+<br />
+Phalanges, <a href="#Page_129">129</a>, <a href="#Page_132">132</a>;<br />
+<span style="margin-left: 1em;">wing finger, <a href="#Page_155">155</a></span><br />
+<br />
+Phillips, Professor John, <a href="#Page_155">155</a><br />
+<br />
+Pigeon, <a href="#Page_119">119</a><br />
+<br />
+Platydactylus, <a href="#Page_21">21</a><br />
+<br />
+Platypus, <a href="#Page_214">214</a><br />
+<br />
+Plesiosaurus, <a href="#Page_6">6</a>, <a href="#Page_73">73</a>, <a href="#Page_75">75</a>, <a href="#Page_93">93</a>, <a href="#Page_189">189</a><br />
+<br />
+Pleininger, <a href="#Page_149">149</a>, <a href="#Page_232">232</a><br />
+<br />
+Pneumatic foramina, <a href="#Page_45">45</a>, <a href="#Page_83">83</a>, <a href="#Page_88">88</a>, <a href="#Page_132">132</a>, <a href="#Page_209">209</a><br />
+<br />
+Pond, Mr., <a href="#Page_34">34</a><br />
+<br />
+Porcupine, <a href="#Page_40">40</a><br />
+<br />
+Porpoise, <a href="#Page_38">38</a>, <a href="#Page_73">73</a>, <a href="#Page_141">141</a>, <a href="#Page_200">200</a><br />
+<br />
+Premaxillary bones, <a href="#Page_77">77</a>, <a href="#Page_200">200</a>, <a href="#Page_205">205</a><br />
+<br />
+Prepubic bones, <a href="#Page_94">94</a>, <a href="#Page_96">96-98</a>, <a href="#Page_194">194</a>, <a href="#Page_204">204</a>, <a href="#Page_205">205</a><br />
+<br />
+Protorosauria, <a href="#Page_192">192</a><br />
+<br />
+<i>Ptenodracon brevirostris</i>, <a href="#Page_64">64</a>, <a href="#Page_99">99</a>, <a href="#Page_167">167</a>, <a href="#Page_169">169</a>, <a href="#Page_192">192</a><br />
+<br />
+Pterodactyle aspects, <a href="#Page_35">35</a>;<br />
+<span style="margin-left: 1em;">avian characters, <a href="#Page_222">222</a>;</span><br />
+<span style="margin-left: 1em;">beak, <a href="#Page_200">200</a>;</span><br />
+<span style="margin-left: 1em;">brain, <a href="#Page_53">53</a>;</span><br />
+<span style="margin-left: 1em;">coracoid, <a href="#Page_113">113</a>;</span><br />
+<span style="margin-left: 1em;">discovery, <a href="#Page_27">27</a>, <a href="#Page_33">33</a>;</span><br />
+<span style="margin-left: 1em;">foot, <a href="#Page_104">104</a>;</span><br />
+<span style="margin-left: 1em;">fore limb, <a href="#Page_117">117</a>;</span><br />
+<span style="margin-left: 1em;">history in Germany, <a href="#Page_31">31</a>, <a href="#Page_148">148</a>;</span><br />
+<span style="margin-left: 1em;">hand, <a href="#Page_130">130</a>;</span><br />
+<span style="margin-left: 1em;">hind limb, <a href="#Page_100">100</a>;</span><br />
+<span style="margin-left: 1em;">long tails, <a href="#Page_156">156</a>;</span><br />
+<span style="margin-left: 1em;">palate, <a href="#Page_71">71</a>;</span><br />
+<span style="margin-left: 1em;">sacrum, <a href="#Page_89">89</a>;</span><br />
+<span style="margin-left: 1em;">short tails, <a href="#Page_165">165</a>;</span><br />
+<span style="margin-left: 1em;">size, <a href="#Page_35">35</a>, <a href="#Page_133">133</a>;</span><br />
+<span style="margin-left: 1em;">sacrum, <a href="#Page_89">89</a>;</span><br />
+<span style="margin-left: 1em;">skull, <a href="#Page_192">192</a>;</span><br />
+<span style="margin-left: 1em;">teeth, <a href="#Page_73">73</a>;</span><br />
+<span style="margin-left: 1em;">vertebr&aelig;, <a href="#Page_80">80</a></span><br />
+<br />
+Pterodactyles from Kansas Chalk, <a href="#Page_177">177</a>, <a href="#Page_181">181</a><br />
+<br />
+&mdash; from Lias Clay, <a href="#Page_135">135</a>, <a href="#Page_147">147</a>, <a href="#Page_152">152</a><br />
+<br />
+&mdash; from Neocomian Sand, <a href="#Page_176">176</a><br />
+<br />
+&mdash; from Oxford Clay, <a href="#Page_155">155</a><br />
+<br />
+&mdash; from Purbeck beds, <a href="#Page_173">173</a><br />
+<br />
+&mdash; from Solenhofen Slate, <a href="#Page_156">156</a>, <a href="#Page_158">158</a><br />
+<br />
+&mdash; from Stonesfield Slate, <a href="#Page_153">153</a>, <a href="#Page_158">158</a><br />
+<br />
+Pterodactylia, <a href="#Page_30">30</a>, <a href="#Page_165">165</a>, <a href="#Page_193">193</a>, <a href="#Page_199">199</a><br />
+<br />
+<i>Pterodactylus antiquus</i>, <a href="#Page_167">167</a>;<br />
+<span style="margin-left: 1em;"><i>brevirostris</i>, <a href="#Page_99">99</a>, <a href="#Page_167">167</a>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>crassirostris</i>, <a href="#Page_156">156</a>;</span><br />
+<span style="margin-left: 1em;"><i>dubius</i>, <a href="#Page_87">87</a>, <a href="#Page_96">96</a>, <a href="#Page_97">97</a>, <a href="#Page_203">203</a>;</span><br />
+<span style="margin-left: 1em;"><i>elegans</i>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>Fraasii</i>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>grandipelvis</i>, <a href="#Page_87">87</a>, <a href="#Page_90">90</a>;</span><br />
+<span style="margin-left: 1em;"><i>grandis</i>, <a href="#Page_102">102</a>, <a href="#Page_167">167</a>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>Kochi</i>, <a href="#Page_12">12</a>, <a href="#Page_61">61</a>, <a href="#Page_87">87</a>, <a href="#Page_90">90</a>, <a href="#Page_168">168</a>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>longirostris</i>, <a href="#Page_28">28</a>, <a href="#Page_90">90</a>, <a href="#Page_96">96</a>, <a href="#Page_101">101</a>, <a href="#Page_103">103</a>, <a href="#Page_105">105</a>, <a href="#Page_167">167</a>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>micronyx</i>, <a href="#Page_105">105</a>, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;"><i>rhamphastinus</i>, <a href="#Page_183">183</a>;</span><br />
+<span style="margin-left: 1em;"><i>scolopaciceps</i>, <a href="#Page_105">105</a>, <a href="#Page_166">166</a>;</span><br />
+<span style="margin-left: 1em;"><i>spectabilis</i>, <a href="#Page_83">83</a>;</span><br />
+<span style="margin-left: 1em;"><i>suevicus</i>, <a href="#Page_169">169</a></span><br />
+<br />
+Pterodermata, <a href="#Page_194">194</a>, <a href="#Page_199">199</a><br />
+<br />
+Pteroid bone of first digit, <a href="#Page_121">121</a><br />
+<br />
+Pteromys, <a href="#Page_24">24</a><br />
+<br />
+Pterosauria, <a href="#Page_187">187</a>, <a href="#Page_193">193</a><br />
+<br />
+Pterygoid bones, <a href="#Page_72">72</a>, <a href="#Page_147">147</a><br />
+<br />
+Pythonomorpha, <a href="#Page_191">191</a><br />
+<br />
+<br />
+<b>Q</b><br />
+<br />
+Quadrate bone, <a href="#Page_12">12</a>, <a href="#Page_68">68</a>, <a href="#Page_77">77</a><br />
+<br />
+Quenstedt, <a href="#Page_231">231</a><br />
+<span class='pagenum'><a name="Page_238" id="Page_238">[Pg 238]</a></span><br />
+<br />
+<b>R</b><br />
+<br />
+Rabbit, <a href="#Page_227">227</a><br />
+<br />
+Radius, <a href="#Page_119">119</a>, <a href="#Page_120">120</a><br />
+<br />
+Redshanks, <a href="#Page_22">22</a><br />
+<br />
+Relation between head and tail, <a href="#Page_157">157</a>, <a href="#Page_193">193</a><br />
+<br />
+Reptile, <a href="#Page_6">6</a>, <a href="#Page_79">79</a>, <a href="#Page_80">80</a><br />
+<br />
+Resin, <a href="#Page_136">136</a><br />
+<br />
+Restorations&mdash;<br />
+<span style="margin-left: 1em;">Campylognathus, palate of, <a href="#Page_71">71</a></span><br />
+<span style="margin-left: 1em;">Dimorphodon, <a href="#Page_143">143</a>, <a href="#Page_147">147</a>, <a href="#Page_164">164</a></span><br />
+<span style="margin-left: 1em;">Ornithocheirus, <a href="#Page_164">164</a></span><br />
+<span style="margin-left: 1em;">Ornithostoma, <a href="#Page_164">164</a>, <a href="#Page_183">183</a></span><br />
+<span style="margin-left: 1em;">Ptenodracon, <a href="#Page_167">167</a></span><br />
+<span style="margin-left: 1em;">Pterodactylus, <a href="#Page_29">29</a>, <a href="#Page_30">30</a></span><br />
+<span style="margin-left: 1em;">Rhamphocephalus, <a href="#Page_164">164</a></span><br />
+<span style="margin-left: 1em;">Rhamphorhynchus, <a href="#Page_161">161</a>, <a href="#Page_164">164</a></span><br />
+<span style="margin-left: 1em;">Scaphognathus, <a href="#Page_163">163</a></span><br />
+<br />
+Rhacophorus, <a href="#Page_19">19</a><br />
+<br />
+Rh&aelig;tic beds, <a href="#Page_184">184</a><br />
+<br />
+Rhamphocephalus, <a href="#Page_113">113</a>, <a href="#Page_136">136</a>, <a href="#Page_153">153</a><br />
+<br />
+Rhamphorhynchus, <a href="#Page_118">118</a>, <a href="#Page_192">192</a>;<br />
+<span style="margin-left: 1em;">foot, <a href="#Page_104">104</a>;</span><br />
+<span style="margin-left: 1em;">hind limb, <a href="#Page_99">99</a>;</span><br />
+<span style="margin-left: 1em;">pelvis, <a href="#Page_95">95</a>;</span><br />
+<span style="margin-left: 1em;">sacrum, <a href="#Page_88">88</a>;</span><br />
+<span style="margin-left: 1em;">skull, <a href="#Page_54">54</a>, <a href="#Page_63">63-6</a>, <a href="#Page_69">69</a>;</span><br />
+<span style="margin-left: 1em;">sternum, <a href="#Page_108">108</a>;</span><br />
+<span style="margin-left: 1em;">tail, <a href="#Page_91">91</a>;</span><br />
+<span style="margin-left: 1em;">teeth, <a href="#Page_73">73</a>;</span><br />
+<span style="margin-left: 1em;">tibia and fibula, <a href="#Page_103">103</a>;</span><br />
+<span style="margin-left: 1em;">web-footed, <a href="#Page_105">105</a></span><br />
+<br />
+<i>Rhamphorhynchus curtimanus</i>, <a href="#Page_163">163</a>;<br />
+<span style="margin-left: 1em;"><i>hirundinaceus</i>, <a href="#Page_163">163</a>;</span><br />
+<span style="margin-left: 1em;"><i>longimanus</i>, <a href="#Page_164">164</a>;</span><br />
+<span style="margin-left: 1em;"><i>phyllurus</i>, <a href="#Page_91">91</a>, <a href="#Page_165">165</a></span><br />
+<br />
+Rhinoceros, <a href="#Page_40">40</a>, <a href="#Page_141">141</a><br />
+<br />
+Rhopoladon, <a href="#Page_97">97</a><br />
+<br />
+Rhynchocephala, <a href="#Page_192">192</a><br />
+<br />
+Roc, <a href="#Page_36">36</a><br />
+<br />
+Rochester, <a href="#Page_136">136</a><br />
+<br />
+Running limb, <a href="#Page_38">38</a><br />
+<br />
+Ryle, Bishop, <a href="#Page_17">17</a><br />
+<br />
+<br />
+<b>S</b><br />
+<br />
+Sacrum, <a href="#Page_87">87</a>, <a href="#Page_88">88</a><br />
+<br />
+St. George, <a href="#Page_15">15</a><br />
+<br />
+St. Ives, <a href="#Page_156">156</a><br />
+<br />
+Sarcorhamphus, <a href="#Page_102">102</a><br />
+<br />
+Saurians, <a href="#Page_27">27</a><br />
+<br />
+Saurischia, <a href="#Page_190">190</a>, <a href="#Page_195">195</a>, <a href="#Page_198">198</a>, <a href="#Page_199">199</a><br />
+<br />
+Sauromorpha, <a href="#Page_191">191</a>, <a href="#Page_192">192</a><br />
+<br />
+Sauropsida, <a href="#Page_188">188</a><br />
+<br />
+Sauropterygia, <a href="#Page_192">192</a><br />
+<br />
+Scaphognathus, <a href="#Page_64">64</a>, <a href="#Page_85">85</a>, <a href="#Page_140">140</a>, <a href="#Page_152">152</a>, <a href="#Page_192">192</a>, <a href="#Page_212">212</a><br />
+<br />
+<i>Scaphognathus crassirostris</i>, <a href="#Page_73">73-5</a>, <a href="#Page_83">83</a><br />
+<br />
+Scapular arch, <a href="#Page_111">111</a>, <a href="#Page_113">113</a><br />
+<br />
+Scelidosaurus, <a href="#Page_135">135</a><br />
+<br />
+Sclerotic circle, <a href="#Page_65">65</a><br />
+<br />
+Seals, <a href="#Page_41">41</a><br />
+<br />
+Sedgwick, Professor Adam, v, <a href="#Page_46">46</a><br />
+<br />
+Shillington, <a href="#Page_77">77</a><br />
+<br />
+Shoebill, <a href="#Page_67">67</a><br />
+<br />
+Shoe-shaped prepubic bones, <a href="#Page_204">204</a>, <a href="#Page_205">205</a><br />
+<br />
+Short-tailed pterodactyles, <a href="#Page_165">165</a>, <a href="#Page_193">193</a><br />
+<br />
+Shoulder-girdle, <a href="#Page_107">107</a>, <a href="#Page_111">111</a>, <a href="#Page_114">114</a>, <a href="#Page_115">115</a>, <a href="#Page_183">183</a><br />
+<br />
+Siberia, <a href="#Page_141">141</a><br />
+<br />
+Simultaneous origin of characters, <a href="#Page_214">214</a>, <a href="#Page_224">224</a><br />
+<br />
+Skin covering, <a href="#Page_40">40</a>, <a href="#Page_41">41</a>, <a href="#Page_58">58</a>, <a href="#Page_139">139</a>, <a href="#Page_140">140</a><br />
+<br />
+Skulls, <a href="#Page_68">68</a><br />
+<br />
+Sloth, <a href="#Page_112">112</a><br />
+<br />
+Snipe, <a href="#Page_47">47</a>, <a href="#Page_68">68</a><br />
+<br />
+Solenhofen Slate, <a href="#Page_28">28</a>, <a href="#Page_32">32</a>, <a href="#Page_88">88</a>, <a href="#Page_153">153</a>, <a href="#Page_156">156</a><br />
+<br />
+S&ouml;mmerring, <a href="#Page_29">29</a><br />
+<br />
+South African reptiles, <a href="#Page_188">188</a>, <a href="#Page_208">208</a>, <a href="#Page_216">216</a><br />
+<br />
+Spotted fly-catcher, <a href="#Page_47">47</a><br />
+<br />
+Squamosal bone, <a href="#Page_12">12</a>, <a href="#Page_13">13</a><br />
+<br />
+Sternal ribs, <a href="#Page_110">110</a><br />
+<br />
+Sternum, <a href="#Page_107">107</a>, <a href="#Page_158">158</a><br />
+<br />
+Stonesfield Slate, <a href="#Page_33">33</a>, <a href="#Page_88">88</a>, <a href="#Page_153">153</a><br />
+<br />
+Structures common to reptiles, <a href="#Page_224">224</a><br />
+<br />
+Stuttgart Museum, <a href="#Page_32">32</a>, <a href="#Page_172">172</a>, <a href="#Page_203">203</a><br />
+<br />
+Swanage, <a href="#Page_172">172</a><br />
+<br />
+Swan, neck of, <a href="#Page_80">80</a>, <a href="#Page_113">113</a><br />
+<br />
+Swift, <a href="#Page_50">50</a><br />
+<br />
+Swimming limb, <a href="#Page_38">38</a><br />
+<br />
+Synotus, <a href="#Page_25">25</a><br />
+<br />
+Syrinx, <a href="#Page_48">48</a><br />
+<br />
+<br />
+<b>T</b><br />
+<br />
+Tail, description of, <a href="#Page_90">90</a>;<br />
+<span style="margin-left: 1em;">in Cretaceous Pterodactyles, <a href="#Page_193">193</a></span><br />
+<span style="margin-left: 1em;">&mdash; long, <a href="#Page_156">156</a>;</span><br />
+<span style="margin-left: 1em;">short, <a href="#Page_166">166</a>;</span><br />
+<span style="margin-left: 1em;">in Dimorphodon, <a href="#Page_145">145</a>;</span><br />
+<span style="margin-left: 1em;">in Ornithocheirus, <a href="#Page_179">179</a></span><br />
+<br />
+Tanystroph&#339;us, long vertebr&aelig; in, <a href="#Page_79">79</a><br />
+<br />
+Tarsal bones, <a href="#Page_102">102</a>, <a href="#Page_207">207</a><br />
+<br />
+Tarso-metatarsus, <a href="#Page_128">128</a><br />
+<span class='pagenum'><a name="Page_239" id="Page_239">[Pg 239]</a></span><br />
+Teeth, <a href="#Page_73">73</a>, <a href="#Page_137">137</a>, <a href="#Page_138">138</a>;<br />
+<span style="margin-left: 1em;">in porpoise, <a href="#Page_40">40</a></span><br />
+<br />
+Temperature of blood, <a href="#Page_56">56</a><br />
+<br />
+Temporal arches, <a href="#Page_68">68</a><br />
+<br />
+&mdash; bone, <a href="#Page_12">12</a><br />
+<br />
+&mdash; fossa, <a href="#Page_67">67</a><br />
+<br />
+Teredo, <a href="#Page_137">137</a><br />
+<br />
+Texas fossils, <a href="#Page_216">216</a><br />
+<br />
+Thecospondylus, <a href="#Page_209">209</a><br />
+<br />
+Theriodont pelvis, <a href="#Page_97">97</a><br />
+<br />
+&mdash; reptiles, <a href="#Page_75">75</a>;<br />
+<span style="margin-left: 1em;">of Russia, <a href="#Page_96">96</a>, <a href="#Page_97">97</a>;</span><br />
+<span style="margin-left: 1em;">of South Africa, <a href="#Page_96">96</a>, <a href="#Page_117">117</a></span><br />
+<br />
+Theropsida, <a href="#Page_188">188</a><br />
+<br />
+Thigh bone, <a href="#Page_100">100</a>, <a href="#Page_206">206</a>, <a href="#Page_211">211</a><br />
+<br />
+Three claws, <a href="#Page_146">146</a>, <a href="#Page_197">197</a><br />
+<br />
+Tibia, <a href="#Page_102">102</a>, <a href="#Page_195">195</a>;<br />
+<span style="margin-left: 1em;">in Iguanodon, <a href="#Page_207">207</a></span><br />
+<br />
+Toothless mammals, <a href="#Page_40">40</a><br />
+<br />
+&mdash; pterodactyles, <a href="#Page_138">138</a>, <a href="#Page_181">181</a>;<br />
+<span style="margin-left: 1em;">beak of pterodactyles, <a href="#Page_150">150</a></span><br />
+<br />
+Transition from reptiles to birds, <a href="#Page_211">211</a><br />
+<br />
+Tree frogs, <a href="#Page_21">21</a><br />
+<br />
+Trias dinosaurs, <a href="#Page_199">199</a><br />
+<br />
+Triceratops, pelvis of, <a href="#Page_204">204</a><br />
+<br />
+Trout, <a href="#Page_139">139</a>;<br />
+<span style="margin-left: 1em;">of New Zealand, <a href="#Page_228">228</a></span><br />
+<br />
+Tuatera, <a href="#Page_13">13</a><br />
+<br />
+T&uuml;bingen Museum, <a href="#Page_32">32</a><br />
+<br />
+Tundras, <a href="#Page_141">141</a><br />
+<br />
+Tunny, <a href="#Page_57">57</a><br />
+<br />
+Turtles, neck bones, <a href="#Page_79">79</a><br />
+<br />
+<br />
+<b>U</b><br />
+<br />
+Ulna, description of, <a href="#Page_119">119</a><br />
+<br />
+Uncinate process of ribs, <a href="#Page_85">85</a><br />
+<br />
+Unlimited time, <a href="#Page_228">228</a><br />
+<br />
+Upper arm bone, <a href="#Page_117">117</a><br />
+<br />
+&mdash; Greensand, remains in, <a href="#Page_136">136</a><br />
+<br />
+&mdash; Lias of Whitby, <a href="#Page_147">147</a><br />
+<br />
+&mdash; Oolites, <a href="#Page_185">185</a>, <a href="#Page_195">195</a><br />
+<br />
+<br />
+<b>V</b><br />
+<br />
+Variation of bones in mammals, <a href="#Page_38">38</a><br />
+<br />
+&mdash; in Pterodactyles, <a href="#Page_229">229</a><br />
+<br />
+Variation of bones in vertebr&aelig;, <a href="#Page_225">225</a><br />
+<br />
+Vertebr&aelig;, caudal, <a href="#Page_89">89</a>, <a href="#Page_92">92</a>, <a href="#Page_203">203</a><br />
+<br />
+&mdash; cervical, <a href="#Page_173">173</a>, <a href="#Page_179">179</a>, <a href="#Page_203">203</a><br />
+<br />
+&mdash; dorsal, <a href="#Page_86">86</a><br />
+<br />
+Vertebral articulation, <a href="#Page_82">82</a>, <a href="#Page_224">224</a><br />
+<br />
+&mdash; column, <a href="#Page_78">78</a><br />
+<br />
+Vulture, neck vertebr&aelig; of, <a href="#Page_80">80</a>;<br />
+<span style="margin-left: 1em;">tibia and fibula of, <a href="#Page_102">102</a></span><br />
+<br />
+Vomer, <a href="#Page_147">147</a><br />
+<br />
+Vomerine bones, <a href="#Page_72">72</a><br />
+<br />
+<br />
+<b>W</b><br />
+<br />
+Wagler, <a href="#Page_29">29</a><br />
+<br />
+Wagner, Andreas, <a href="#Page_30">30</a>, <a href="#Page_148">148</a>, <a href="#Page_231">231</a><br />
+<br />
+Walker, J. F., <a href="#Page_54">54</a><br />
+<br />
+Wealden beds, Pterodactyles in, <a href="#Page_55">55</a>, <a href="#Page_84">84</a>;<br />
+<span style="margin-left: 1em;">bones in, <a href="#Page_135">135</a>, <a href="#Page_136">136</a>, <a href="#Page_173">173</a></span><br />
+<br />
+Weight of Pterodactyle, <a href="#Page_106">106</a><br />
+<br />
+Whinchat, <a href="#Page_47">47</a><br />
+<br />
+Whitby, <a href="#Page_33">33</a>, <a href="#Page_135">135</a><br />
+<br />
+Williston, Professor W. S., <a href="#Page_75">75</a>, <a href="#Page_82">82</a>, <a href="#Page_92">92</a>, <a href="#Page_98">98</a>, <a href="#Page_105">105</a>, <a href="#Page_110">110</a><br />
+<br />
+Willow-wren, <a href="#Page_47">47</a><br />
+<br />
+Wing finger, <a href="#Page_116">116</a>, <a href="#Page_130">130</a>, <a href="#Page_133">133</a>, <a href="#Page_151">151</a>, <a href="#Page_178">178</a>, <a href="#Page_197">197</a><br />
+<br />
+&mdash; membrane, <a href="#Page_32">32</a>, <a href="#Page_121">121</a>, <a href="#Page_140">140</a>, and <a href="#Fig_47">frontispiece</a><br />
+<br />
+&mdash; metacarpal, <a href="#Page_123">123</a>;<br />
+<span style="margin-left: 1em;">in Dimorphodon, <a href="#Page_151">151</a>;</span><br />
+<span style="margin-left: 1em;">in Ornithostoma, <a href="#Page_184">184</a>;</span><br />
+<span style="margin-left: 1em;">in bats, <a href="#Page_131">131</a></span><br />
+<br />
+Wings of Dragons, <a href="#Page_16">16</a><br />
+<br />
+Winkler, T. C., <a href="#Page_231">231</a><br />
+<br />
+Woodwardian Museum, <a href="#Page_34">34</a><br />
+<br />
+Wood-wren, <a href="#Page_47">47</a><br />
+<br />
+Wrist bones, <a href="#Page_122">122</a><br />
+<br />
+W&uuml;rtemberg, <a href="#Page_33">33</a><br />
+<br />
+<br />
+<b>Y</b><br />
+<br />
+Yale College Museum, <a href="#Page_32">32</a><br />
+<br />
+York Museum, <a href="#Page_34">34</a>, <a href="#Page_176">176</a><br />
+<br />
+<br />
+<b>Z</b><br />
+<br />
+Zittel, Karl von, <a href="#Page_31">31</a>, <a href="#Page_157">157</a>, <a href="#Page_165">165</a>, <a href="#Page_231">231</a><br />
+<br />
+Zygomatic arch, <a href="#Page_67">67</a><br />
+</p></div>
+
+<p><span class='pagenum'><a name="Page_240" id="Page_240">[Pg 240]</a></span></p>
+
+<h5>
+PRINTED BY<br />
+<br />
+WILLIAM BRENDON AND SON<br />
+<br />
+PLYMOUTH<br />
+</h5>
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley
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+The Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Dragons of the Air
+       An Account of Extinct Flying Reptiles
+
+Author: H. G. Seeley
+
+Release Date: February 18, 2011 [EBook #35316]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK DRAGONS OF THE AIR ***
+
+
+
+
+Produced by Chris Curnow and the Online Distributed
+Proofreading Team at http://www.pgdp.net (This file was
+produced from images generously made available by The
+Internet Archive)
+
+
+
+
+
+
+
+
+
+                          DRAGONS OF THE AIR
+
+
+
+
+    [Illustration: FIG. 47.  RHAMPHORHYNCHUS PHYLLUNUS
+
+    SHOWING THE PRESERVATION OF THE WING MEMBRANES
+
+    _From the Lithographic slate of Eichstaedt, Bavaria_
+
+                                                     _Frontispiece_]
+
+
+
+
+                          DRAGONS OF THE AIR
+
+                             AN ACCOUNT OF
+                        EXTINCT FLYING REPTILES
+
+                                  BY
+
+                         H. G. SEELEY, F.R.S.
+
+  PROFESSOR OF GEOLOGY IN KING'S COLLEGE, LONDON; LECTURER ON GEOLOGY
+        AND MINERALOGY IN THE ROYAL INDIAN ENGINEERING COLLEGE
+
+                       WITH EIGHTY ILLUSTRATIONS
+
+                      "I AM A BROTHER OF DRAGONS"
+                                                  _Job_ xxx. 29
+
+
+                      NEW YORK: D. APPLETON & CO.
+                        LONDON: METHUEN & CO.
+
+                                 1901
+
+
+
+
+PREFACE
+
+
+I was a student of law at a time when Sir Richard Owen was lecturing on
+Extinct Fossil Reptiles. The skill of the great master, who built bones
+together as a child builds with a box of bricks, taught me that the laws
+which determine the forms of animals were less understood at that time
+than the laws which govern the relations of men in their country. The
+laws of Nature promised a better return of new knowledge for reasonable
+study. A lecture on Flying Reptiles determined me to attempt to fathom
+the mysteries which gave new types of life to the Earth and afterwards
+took them away.
+
+Thus I became the very humble servant of the Dragons of the Air. Knowing
+but little about them I went to Cambridge, and for ten years worked with
+the Professor of Geology, the late Rev. Adam Sedgwick, LL.D., F.R.S., in
+gathering their bones from the so-called Cambridge Coprolite bed, the
+Cambridge Greensand. The bones came in thousands, battered and broken,
+but instructive as better materials might not have been. My rooms
+became filled with remains of existing birds, lizards, and mammals,
+which threw light on the astonishing collection of old bones which I
+assisted in bringing together for the University.
+
+In time I had something to say about Flying Animals which was new. The
+story was told in the theatre of the Royal Institution, in a series of
+lectures. Some of them were repeated in several English towns. There was
+still much to learn of foreign forms of flying animals; but at last,
+with the aid of the Government grant administered by the Royal Society,
+and the chiefs of the great Continental museums, I saw all the specimens
+in Europe.
+
+So I have again written out my lectures, with the aid of the latest
+discoveries, and the story of animal structure has lost nothing in
+interest as a twice-told tale. It still presents in epitome the story of
+life on the Earth. He who understands whence the Flying Reptiles came,
+how they endured, and disappeared from the Earth, has solved some of the
+greatest mysteries of life. I have only contributed something towards
+solving the problems.
+
+In telling my story, chiefly of facts in Nature, an attempt is made to
+show how a naturalist does his work, in the hope that perhaps a few
+readers will find happiness in following the workings of the laws of
+life. Such an illumination has proved to many worth seeking, a solid
+return for labour, which is not to be marketed on the Exchange, but may
+be taken freely without exhausting the treasury of Nature's truths. Such
+outlines of knowledge as here are offered to a larger public, may also,
+I believe, be acceptable to students of science and scientific men.
+
+The drawings given in illustration of the text have been made for me by
+Miss E. B. Seeley.
+
+                                                              H. G. S.
+  KENSINGTON, _May, 1901_
+
+
+
+
+CONTENTS
+
+
+                                                                    PAGE
+  CHAPTER I.
+  FLYING REPTILES                                                      1
+
+  CHAPTER II.
+  HOW A REPTILE IS KNOWN                                               4
+
+  CHAPTER III.
+  A REPTILE IS KNOWN BY ITS BONES                                     11
+
+  CHAPTER IV.
+  ANIMALS WHICH FLY                                                   15
+
+  CHAPTER V.
+  DISCOVERY OF THE PTERODACTYLE                                       27
+
+  CHAPTER VI.
+  HOW ANIMALS ARE INTERPRETED BY THEIR BONES                          37
+
+  CHAPTER VII.
+  INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS                 45
+
+  CHAPTER VIII.
+  THE PLAN OF THE SKELETON                                            58
+
+  CHAPTER IX.
+  THE BACKBONE, OR VERTEBRAL COLUMN                                   78
+
+  CHAPTER X.
+  THE HIP-GIRDLE AND HIND LIMB                                        93
+
+  CHAPTER XI.
+  SHOULDER-GIRDLE AND FORE LIMB                                      107
+
+  CHAPTER XII.
+  EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS                  134
+
+  CHAPTER XIII.
+  ANCIENT ORNITHOSAURS FROM THE LIAS                                 143
+
+  CHAPTER XIV.
+  ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS                       153
+
+  CHAPTER XV.
+  ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS                        172
+
+  CHAPTER XVI.
+  CLASSIFICATION OF THE ORNITHOSAURIA                                187
+
+  CHAPTER XVII.
+  FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM 196
+
+  CHAPTER XVIII.
+  HOW PTERODACTYLES MAY HAVE ORIGINATED                              213
+
+  APPENDIX                                                           231
+
+  INDEX                                                              233
+
+
+
+
+LIST OF ILLUSTRATIONS
+
+ FIG.                                                               PAGE
+  47. Wings of Rhamphorhynchus                            _Frontispiece_
+   1. Lung of the lung-fish Ceratodus                                  5
+   2. Attachment of the lower jaw in a Mammal and in a Pterodactyle   12
+   3. Chaldaean Dragon                                                 15
+   4. Winged human figure from the Temple of Ephesus                  16
+   5. Flying fish Exocoetus                                           18
+   6. Flying Frog                                                     19
+   7. Flying Lizard (Draco)                                           20
+   8. Birds in flight                                                 22
+   9. Flying Squirrel (Pteromys)                                      24
+  10. Bats, flying and walking                                        25
+  11. Skeleton of _Pterodactylus longirostris_                        28
+  12. The skeleton restored                                           29
+  13. The animal form restored                                        30
+  14. Fore limbs in four types of mammals                             38
+  15. Pneumatic foramen in Pterodactyle bone                          46
+  16. Lungs of the bird Apteryx                                       48
+  17. Air cells in the body of an Ostrich                             49
+  18. Lung of a Chameleon                                             51
+  19. Brain in Pterodactyle, Mammal, Bird, and Reptiles               53
+  20. Skull of Kingfisher and Rhamphorhynchus                         63
+  21. Skull of Heron and Rhamphorhynchus                              65
+  22. Palate of Macrocercus and ? Campylognathus                      71
+  23. Lower jaw of Echidna and Ornithostoma                           76
+  24. First two neck vertebrae of Ornithocheirus                       81
+  25. Middle neck vertebrae of Ornithocheirus                          83
+  26. Back vertebra of Ornithocheirus and Crocodile                   86
+  27. Sacrum, with hip bones, of Rhamphorhynchus                      88
+  28. Extremity of tail of _Rhamphorhynchus phyllurus_                91
+  29. Hip-girdle bones in Apteryx and Rhamphorhynchus                 95
+  30. Pelvis with prepubic bone in Pterodactylus                      96
+  31. Pelvis with prepubic bones in Rhamphorhynchus                   97
+  32. Pelvis of an Alligator seen from below                          98
+  33. Femora: Echidna, Ornithocheirus, Ursus                         100
+  34. Tibia and fibula: Dimorphodon and Vulture                      102
+  35. Metatarsus and digits in three Pterodactyles                   104
+  36. Sternum in Cormorant and Rhamphorhynchus                       108
+  37. Sternum in Ornithocheirus                                      109
+  38. Shoulder-girdle bones in a bird and three Pterodactyles        113
+  39. The Notarium from the back of Ornithocheirus                   115
+  40. The shoulder-girdle of Ornithocheirus                          115
+  41. Humerus of Pigeon and Ornithocheirus                           119
+  42. Fore-arm of Golden Eagle and Dimorphodon                       120
+  43. Wrist bones of Ornithocheirus                                  124
+  44. Clawed digits of the hand in two Pterodactyles                 125
+  45. Claw from the hand of Ornithocheirus                           129
+  46. The hand in Archaeopteryx and the Ostrich                       130
+  48. Slab of Lias with bones of Dimorphodon          _To face page_ 143
+  49. Dimorphodon (restored form) at rest                            144
+  50. Dimorphodon (restored form of the animal)       _To face page_ 145
+  51. Dimorphodon skeleton, walking as a quadruped          "   "    146
+  52. Dimorphodon skeleton as a biped                       "   "    147
+  53. Lower jaw of Dorygnathus                                       149
+  54. Dimorphodon (wing membranes spread for flight)  _To face page_ 150
+  55. Pelvis of Dimorphodon                                          151
+  56. Rhamphorhynchus skeleton (restored)                            161
+  57. Scaphognathus (restoration of 1875)                            163
+  58. Six restorations of Ornithosaurs                               164
+  59. Ptenodracon skeleton (restored)                                167
+  60. _Cycnorhamphus suevicus_ slab with bones        _To face page_ 168
+  61. _Cycnorhamphus suevicus_ (form of the animal)   _To face page_ 169
+  62. _Cycnorhamphus suevicus_ skeleton (restored)                   170
+  63. _Cycnorhamphus Fraasi_ (restored skeleton form
+          of the animal)                              _To face page_ 170
+  64. _Cycnorhamphus Fraasi_ (restoration of the form
+          of the body)                                _To face page_ 171
+  65. Neck vertebra of Doratorhynchus from the Purbeck               173
+  66. Neck bone of Ornithodesmus from the Wealden                    173
+  67. Sternum of Ornithodesmus, seen from the front                  175
+  68. Sternum of Ornithodesmus, side view, showing the keel          175
+  69. Diagram of known parts of skull of Ornithocheirus              177
+  70. Neck bone of Ornithocheirus                                    179
+  71. Jaws of Ornithocheirus from the Chalk                          180
+  72. Palate of the English Toothless Pterodactyle                   181
+  73. Two views of the skull of Ornithostoma (Pteranodon)            182
+  74. Skeleton of Ornithostoma                                       183
+  75. Comparison of six skulls of Ornithosaurs                       192
+  76. Pelvis of Ornithostoma                                         195
+  77. Skull of Anchisaurus and Dimorphodon                           199
+  78. Skull of Ornithosuchus and Dimorphodon                         201
+  79. The pelvis in Ornithosaur and Dinosaur                         204
+  80. The prepubic bones in Dimorphodon and Iguanodon                206
+
+    These figures are greatly reduced in size, and when two or more
+    bones are shown in the same figure all are brought to the same size
+    to facilitate the comparison.
+
+
+
+
+DRAGONS OF THE AIR
+
+
+
+
+CHAPTER I
+
+FLYING REPTILES
+
+
+The history of life on the earth during the epochs of geological time
+unfolds no more wonderful discovery among types of animals which have
+become extinct than the family of fossils known as flying reptiles. Its
+coming into existence, its structure, and passing away from the living
+world are among the great mysteries of Nature.
+
+The animals are astonishing in their plan of construction. In aspect
+they are unlike birds and beasts which, in this age, hover over land and
+sea. They gather into themselves in the body of a single individual,
+structures which, at the present day, are among the most distinctive
+characters of certain mammals, birds, and reptiles.
+
+The name "flying reptile" expresses this anomaly. Its invention is due
+to the genius of the great French naturalist Cuvier, who was the first
+to realise that this extinct animal, entombed in slabs of stone, is one
+of the wonders of the world.
+
+The word "reptile" has impressed the imagination with unpleasant sound,
+even when the habits of the animals it indicates are unknown. It is
+familiarly associated with life which is reputed venomous, and is
+creeping and cold. Its common type, the serpent, in many parts of the
+world takes a yearly toll of victims from man and beast, and has become
+the representative of silent, active strength, dreaded craft, and
+danger.
+
+Science uses the word "reptile" in a more exact way, to define the
+assemblage of cold-blooded animals which in familiar description are
+separately named serpents, lizards, turtles, hatteria, and crocodiles.
+
+Turtles and the rest of them survive from great geological antiquity.
+They present from age to age diversity of aspect and habit, and in
+unexpected differences of outward proportion of the body show how the
+laws of life have preserved each animal type. For the vital organs which
+constitute each animal a reptile, and the distinctive bony structures
+with which they are associated, remain unaffected, or but little
+modified, by the animal's external change in appearance.
+
+The creeping reptile is commonly imagined as the antithesis of the bird.
+For the bird overcomes the forces that hold even man to the earth, and
+enjoys exalted aerial conditions of life. Therefore the marvel is shared
+equally by learned and unlearned, that the power of flight should have
+been an endowment of animals sprung from the breed of serpents, or
+crocodiles, enabling them to move through the air as though they too
+were of a heaven-born race. The wonder would not be lessened if the
+animal were a degraded representative of a nobler type, or if it should
+be demonstrated that even beasts have advanced in the battle of life.
+The winged reptile, when compared with a bird, is not less astounding
+than the poetic conceptions in Milton's _Paradise Lost_ of degradation
+which overtakes life that once was amongst the highest. And on the other
+hand, from the point of view of the teaching of Darwin in the theories
+of modern science, we are led to ask whether a flying reptile may not be
+evidence of the physical exaltation which raises animals in the scale of
+organisation. The dominance upon the earth of flying reptiles during the
+great middle period of geological history will long engage the interest
+of those who can realise the complexity of its structure, or care to
+unravel the meaning of the procession of animal forms in successive
+geological ages which preceded the coming of man.
+
+The outer vesture of an animal counts for little in estimating the value
+of ties which bind orders of animals together, which are included in the
+larger classes of life. The kindred relationship which makes the snake
+of the same class as the tortoise is determined by the soft vital
+organs--brain, heart, lungs--which are the essentials of an animal's
+existence and control its way of life. The wonder which science weaves
+into the meaning of the word "reptile," "bird," or "mammal," is partly
+in exhibiting minor changes of character in those organs and other soft
+parts, but far more in showing that while they endure unchanged, the
+hard parts of the skeleton are modified in many ways. For the bones of
+the reptile orders stretch their affinities in one direction towards the
+skeletons of salamanders and fishes; and extend them also at the same
+time in other directions, towards birds and mammals. This mystery we may
+hope to partly unravel.
+
+
+
+
+CHAPTER II
+
+HOW A REPTILE IS KNOWN
+
+
+DEFINITION OF REPTILES BY THEIR VITAL ORGANS
+
+The relations of reptiles to other animals may be stated so as to make
+evident the characters and affinities which bind them together. Early in
+the nineteenth century naturalists included with the Reptilia the tribe
+of salamanders and frogs which are named Amphibia. The two groups have
+been separated from each other because the young of Amphibia pass
+through a tadpole stage of development. They then breathe by gills, like
+fishes, taking oxygen from the air which is suspended in water, before
+lungs are acquired which afterwards enable the animals to take oxygen
+directly from the air. The amphibian sometimes sheds the gills, and
+leaves the water to live on land. Sometimes gills and lungs are retained
+through life in the same individual. This amphibian condition of lung
+and gill being present at the same time is paralleled by a few fishes
+which still exist, like the Australian _Ceratodus_, the lung-fish, an
+ancient type of fish which belongs to early days in geological time.
+
+This metamorphosis has been held to separate the amphibian type from
+the reptile because no existing reptile develops gills or undergoes a
+metamorphosis. Yet the character may not be more important as a ground
+for classification than the community of gills and lungs in the fish and
+amphibian is ground for putting them together in one natural group. For
+although no gills are found in reptiles, birds, or mammals, the embryo
+of each in an early stage of development appears to possess gill-arches,
+and gill-clefts between them, through which gills might have been
+developed, even in the higher vertebrates, if the conditions of life had
+been favourable to such modification of structure. In their bones
+Reptiles and Amphibia have much in common. Nearly all true reptiles lay
+eggs, which are defined like those of birds by comparatively large size,
+and are contained in shells. This condition is not usual in amphibians
+or fishes. When hatched the young reptile is completely formed, the
+image of its parent, and has no need to grow a covering to its skin like
+some birds, or shed its tail like some tadpoles. The reptile is like the
+bird in freedom from important changes of form after the egg is hatched;
+and the only structure shed by both is the little horn upon the nose,
+with which the embryo breaks the shell and emerges a reptile or a bird,
+growing to maturity with small subsequent variations in the proportions
+of the body.
+
+  [Illustration: FIG. 1  LUNG OF THE FISH CERATODUS
+
+  Partly laid open to show its chambered structure (After Guenther)]
+
+
+THE REPTILE SKIN
+
+Between one class of animals and another the differences in the
+condition of the skin are more or less distinctive. In a few amphibians
+there are some bones in the skin on the under side of the body, though
+the skin is usually naked, and in frogs is said to transmit air to the
+blood, so as to exercise a respiratory function of a minor kind. This
+naked condition, so unlike the armoured skin of the true Reptilia,
+appears to have been paralleled by a number of extinct groups of fossils
+of the Secondary rocks, such as Ichthyosaurs and Plesiosaurs, which were
+aquatic, and probably also by some Dinosauria, which were terrestrial.
+
+Living reptiles are usually defended with some kind of protection to the
+skin. Among snakes and lizards the skin has commonly a covering of
+overlapping scales, usually of horny or bony texture. The tortoise and
+turtle tribe shut up the animal in a true box of bone, which is cased
+with an armour of horny plates. Crocodiles have a thick skin embedding a
+less continuous coat of mail. Thus the skin of a reptile does not at
+first suggest anything which might become an organ of flight; and its
+dermal appendages, or scales, may seem further removed from the feathers
+which ensure flying powers to the bird than from the naked skin of a
+frog.
+
+
+THE REPTILE BRAIN
+
+Although the mode of development of the young and the covering of the
+skin are conspicuous among important characters by which animals are
+classified, the brain is an organ of some importance, although of
+greater weight in the higher Vertebrata than in its lower groups.
+Reptiles have links in the mode of arrangement of the parts of their
+brains with fishes and amphibians. The regions of that organ are
+commonly arranged in pairs of nervous masses, known as (1) the olfactory
+lobes, (2) the cerebrum, behind which is the minute pineal body,
+followed by (3) the pair of optic lobes, and hindermost of all (4) the
+single mass termed the cerebellum. These parts of the brain are extended
+in longitudinal order, one behind the other in all three groups. The
+olfactory lobes of the brain in Fishes may be as large as the cerebrum;
+but among Reptiles and Amphibians they are relatively smaller, and they
+assume more of the condition found in mammals like the Hare or Mole,
+being altogether subordinate in size. And the cerebral masses begin to
+be wider and higher than the other parts of the brain, though they do
+not extend forward above the olfactory lobes, as is often seen in
+Mammals. In Crocodiles the cerebral hemispheres have a tendency to a
+broad circular form. Among Chelonian reptiles that region of the brain
+is more remarkable for height. Lizards and Ophidians both have this part
+of the brain somewhat pear-shaped, pointed in front, and elongated. The
+amphibian brain only differs from the lizard type in degree; and
+differences between lizards' and amphibian brains are less noticeable
+than between the other orders of reptiles. The reptilian brain is easily
+distinguished from that of all other animals by the position and
+proportions of its regions (see Fig. 19, p. 53).
+
+Birds have the parts of the brain formed and arranged in a way that is
+equally distinctive. The cerebral lobes are relatively large and convex,
+and deserve the descriptive name "hemispheres." They are always smooth,
+as among the lower Mammals, and extend backward so as to abut against
+the hind brain, termed the cerebellum. This junction is brought about in
+a peculiar way. The cerebral hemispheres in a bird do not extend
+backward to override the optic lobes, and hide them, as occurs among
+adult mammals, but they extend back between the optic lobes, so as to
+force them apart and push them aside, downward and backward, till they
+extend laterally beyond the junction of the cerebrum with the
+cerebellum. The brain of a Bird is never reptilian; but in the young
+Mammal the brain has a very reptilian aspect, because both have their
+parts primarily arranged in a line. Therefore the brain appears to
+determine the boundary between bird and reptile exactly.
+
+
+REPTILIAN BREATHING ORGANS
+
+The breathing organs of Birds and Reptiles which are associated with
+these different types of brain are not quite the same. The Frog has a
+cellular lung which, in the details of the minute sacs which branch and
+cluster at the terminations of the tubes, is not unlike the condition in
+a Mammal. In a mammal respiration is aided by the bellows-like action of
+the muscles connected with the ribs, which encase the cavity where the
+lungs are placed, and this structure is absent in the Frog and its
+allies. The Frog, on the other hand, has to swallow air in much the same
+way as man swallows water. The air is similarly grasped by the muscles,
+and conveyed by them downward to the lungs. Therefore a Frog keeps its
+mouth shut, and the animal dies from want of air if its mouth is open
+for a few minutes.
+
+Crocodiles commonly lie in the sun with their mouths widely open. The
+lungs in both Crocodiles and Turtles are moderately dense, traversed by
+great bronchial tubes, but do not differ essentially in plan from those
+of a Frog, though the great branches of the bronchial tubes are
+stronger, and the air chambers into which the lung is divided are
+somewhat smaller. The New Zealand Hatteria has the lungs of this
+cellular type, though rather resembling the amphibian than the
+Crocodile. The lungs during life in all these animals attain
+considerable size, the maximum dimensions being found in the terrestrial
+tortoises, which owe much of their elevated bulk to the dimensions of
+the air cells which form the lungs.
+
+The lungs of Serpents and Lizards are formed on a different plan. In
+both those groups of reptiles the dense cellular tissue is limited to
+the part of the lung which is nearest to the throat. This network of
+blood vessels and air cells extends about the principal bronchial tube
+much as in other animals, but as it extends backward the blood vessels
+become few until the _tubular_ lung appears in its hinder part, as it
+extends down the body, almost as simple in structure as the air bladder
+of a fish. Among Serpents only one of these tubular lungs is commonly
+present, and the structure has a less efficient appearance as a
+breathing organ than the single lung of the fish _Ceratodus_ (Fig. 1).
+The Chameleons are a group of lizards which differ in many ways from
+most of their nearest kindred, and the lungs, while conforming in
+general plan to the lizard type in being dense at the throat, and a
+tubular bladder in the body, give off on both sides a number of short
+lateral branches like the fingers of a glove (Fig. 18, p. 51).
+
+Thus the breathing organs of reptiles present two or three distinct
+types which have caused Serpents and Lizards to be associated in one
+group by most naturalists who have studied their anatomy; while
+Crocodiles and Chelonians represent a type of lung which is quite
+different, and in those groups has much in common. These characters of
+the breathing organs contribute to separate the cold-blooded armoured
+reptiles from the warm-blooded birds clothed with feathers, as well as
+from the warm-blooded mammals which suckle their young; for both these
+higher groups have denser and more elastic spongy lung tissue.
+
+It will be seen hereafter that many birds in the most active development
+of their breathing organs substantially revert to the condition of the
+Serpent or Chameleon in a somewhat modified way. Because, instead of
+having one great bronchial tube expanded to form a vast reservoir of air
+which can be discharged from the lung in which the reptile has
+accumulated it, the bird has the lateral branches of the bronchial tubes
+prolonged so as to pierce the walls of the lung, when its covering
+membrane expands to form many air cells, which fill much of the cavity
+of the bird's body (see Fig. 16). Thus the bird appears to combine the
+characters of such a lung as that of a Crocodile, with a condition which
+has some analogy with the lung of a Chameleon. It is this link of
+structure of the breathing organs between reptiles and birds that
+constitutes one of the chief interests of flying reptiles, for they
+prove to have possessed air cells prolonged from the lungs, which
+extended into the bones.
+
+
+
+
+CHAPTER III
+
+A REPTILE IS KNOWN BY ITS BONES
+
+
+Such are a few illustrations of ways in which reptiles resemble other
+animals, and differ from them, in the organs by means of which the
+classification of animals is made. But such an idea is incomplete
+without noticing that the bony framework of the body associated with
+such vital organs also shows in its chief parts that reptiles are easily
+recognised by their bones. I will therefore briefly state how reptiles
+are defined in some regions of the skeleton, for in tracing the history
+of reptile life the bones are the principal remains of animals preserved
+in the rocks; and the soft organs which have perished can only be
+inferred to have been present from the persistence of durable
+characteristic parts of the skeleton, which are associated with those
+soft organs in animals which exist at the present day, and are unknown
+in other animals in which the skeleton is different.
+
+
+THE HANG OF THE LOWER JAW
+
+The manner in which the lower jaw is connected with the skull yields one
+of the most easily recognised differences between the great groups of
+vertebrate animals.
+
+_In Mammals._--In every mammal--such as the Dog or Sheep--the lower jaw,
+which is formed of one bone on each side, joins directly on to the head
+of the animal, and moves upon a bone of the skull which is named the
+temporal bone. This character is sufficient to prove, by the law of
+association of soft and hard parts of the body, that such an animal had
+warm blood and suckled its young.
+
+  [Illustration: FIG. 2   _PTERODACTYLUS KOCHI_   SKULL OF BEAR
+
+  Comparison to show the articulation with the lower jaw in a mammal
+  and _Pterodactylus Kochi_. The quadrate bone is lettered Q in this
+  Pterodactyle, and comes between the skull and the lower jaw like the
+  quadrate bone in a bird and in lizards.]
+
+_In Birds._--In birds a great difference is found in this region of the
+head. The temporal bone, which it will be more convenient to name the
+squamosal bone, from its squamous or scale-like form, is still a part of
+the brain case, and assists in covering the brain itself, exactly as
+among mammals. But the lower jaw is now made up of five or six bones.
+And between the hindermost and the squamosal there is an intervening bar
+of bone, unknown among mammalia, which moves upon the skull by a joint,
+just as the lower jaw moves upon it. This movable bone unites with parts
+of the palate and the face, and is known as the quadrate bone. Its
+presence proves that the animal possessing it laid eggs, and if the
+face bones join its outer border just above the lower jaw, it proves
+that the animal possessed hot blood.
+
+_In Reptiles._--All reptiles are also regarded as possessing the
+quadrate bone. But the squamosal bone with which it always unites is in
+less close union with the brain case, and never covers the brain itself.
+Serpents show an extreme divergence in this condition from birds, for
+the squamosal bone appears to be a loose external plate of bone which
+rests upon the compact brain case and gives attachment to the quadrate
+bone which is as free as in a bird. Among Lizards the quadrate bone is
+usually almost as free. In the other division of existing Reptilia,
+including Crocodiles, the New Zealand lizard-like reptile Hatteria,
+called Tuatera, and Turtles, the squamosal and quadrate bones are firmly
+united with the bones of the brain case, face, and palate, so that the
+quadrate bone has no movement; and the same condition appears in
+amphibians, such as Toads and Frogs. With these conditions of the
+quadrate bone are associated cold blood, terrestrial life, and young
+developed from eggs.
+
+_In Fishes._--Bony fishes, and all others in which separate bones build
+up the skull, differ from Reptiles and Birds much as those animals
+differ from Mammals. The union of the lower jaw with the skull becomes
+complicated by the presence of additional bones. The quadrate bone still
+forms a pulley articulation upon which the lower jaw works, but between
+it and the squamosal bone is the characteristic bone of the fish known
+as the hyomandibular, commonly connected with opercular bones and
+metapterygoid which intervene, and help to unite the quadrate with the
+brain case. In the Cartilaginous fishes there is only one bone
+connecting the jaws with the skull on each side. This appears to prove
+that just as the structure of the arch of bones suspending the jaw may
+be complicated by the mysterious process called segmentation, which
+separates a bone into portions, so simplification and variation may
+result because the primitive divisions of the material cease to be made
+which exists before bones are formed.
+
+The principal regions of the skull and skeleton all vary in the chief
+groups of animals with backbones; so that the Reptile may be recognised
+among fossils, even in extinct groups of animals and occasionally
+restored from a fragment, to the aspect which characterised it while it
+lived.
+
+
+
+
+CHAPTER IV
+
+ANIMALS WHICH FLY
+
+
+The nature of a reptile is now sufficiently intelligible for something
+to be said concerning flight, and structures by means of which some
+animals lift themselves in the air. It is not without interest to
+remember that, from the earliest periods in human records,
+representations have been made of animals which were furnished with
+wings, yet walked upon four feet, and in their typical aspect have the
+head shaped like that of a bird. They are commonly named Dragons.
+
+
+FLYING DRAGONS
+
+  [Illustration: FIG. 3  From _The Battle between Bel and the Dragon_]
+
+The effigy of the dragon survives to the present day in the figure over
+which St. George triumphs, on the reverse of the British sovereign. In
+the luxuriant imaginations of ancient Eastern peoples, dating back to
+prehistoric ages, perhaps 5000 B.C., the dragons present an astonishing
+constancy of form. In after-times they underwent a curious evolution, as
+the conception of Babylon and Egypt is traced through Assyria to Greece.
+The Wings, which had been associated at first with the fore limb of the
+typical dragon, become characteristic of the Lion, and of the poet's
+winged Horse, and finally of the Human figure itself, carved on the
+great columns of the Greek temples of Ephesus. These flying animals are
+historically descendants of the same common stock with the dragons of
+China and Japan, which still preserve the aspect of reptiles. Their
+interest is chiefly in evidence of a latent spirit of evolution in days
+too remote for its meaning to be now understood, which has carried the
+winged forms higher and ever higher in grade of organisation, till their
+wings ceased to be associated with feelings of terror. The Hebrew
+cherubim are regarded by H. E. Ryle, Bishop of Exeter, as probably
+Dragons, and the figure of the conventional angel is the human form of
+the Dragon.
+
+  [Illustration: FIG. 4.  FIGURE FROM THE TEMPLE OF EPHESUS]
+
+
+ORGANS OF FLIGHT
+
+Turning from this reference to the realm of mythology to existing
+nature, the power of flight is popularly associated with all the chief
+types of vertebrate animals--fishes, frogs, lizards, birds, and mammals.
+Many of the animals ill deserve the name of flyers, and most are
+exceptions to different conditions of existence which control their
+kindred, but it is convenient to examine for a little the nature of the
+structures by which this movement in the air, which is not always
+flight, is made possible. Certain fishes, like the lung-fish Ceratodus,
+of Queensland, and the mud-fish Lepidosiren, are capable of leaving the
+water and living on land, and for a time breathe air. But neither these
+fishes nor Periophthalmus, which runs with rapid movement of its fins
+and carries the body more or less out of water, or the climbing perch,
+Anabas, carried out of water over the country by Indian jugglers, ever
+put on the slightest approach to wings.
+
+
+FLYING FISHES
+
+  [Illustration: FIG. 5.  THE FLYING FISH EXOCOETUS
+
+  With the fins extended moving through the air]
+
+The flight of fishes is a kind of parachute support not unlike that by
+which a folded paper is made to travel in the air. It is chiefly seen in
+the numerous species of a genus Exocoetus, allied to the gar-pike
+(Belone), which is common in tropical seas, and usually from a foot to
+eighteen inches long. They emerge from the water, and for a time support
+themselves in the air by means of the greatly developed breast fins,
+which sometimes extend backward to the tail fin. Although these fins
+appear to correspond to the fore limbs of other animals, they may not be
+moved at the will of the fish like the wing of a bird. When the flying
+fishes are seen in shoals in the vicinity of ships, those fins remain
+extended, so that the fish is said sometimes to travel 200 yards at a
+speed of fifteen miles an hour, rising twenty feet or more above the
+surface of the sea, travelling in a straight line, though sometimes
+influenced by the wind. Here the organ, which is at once a fin and a
+wing, consists of a number of thin long rods, or rays, which are
+connected by membrane, and vary in length to form an outline not unlike
+the wing of a bird which tapers to a point. The interest of these
+animals is chiefly in the fact that flight is separated from the
+condition of having lungs with which it is associated in birds, for
+although the flying fish has an air bladder, there is no duct to connect
+it with the throat.
+
+
+FLYING FROGS
+
+  [Illustration: FIG. 6.  THE FLYING FROG (RHACOPHORUS)
+
+  The membranes of the foot and hand extend between the metatarsal and
+  metacarpal bones, as well as the bones of the digits.]
+
+Among amphibians the organs of flight are also of a parachute kind, but
+of a different nature. They are seen in certain frogs which frequent
+trees, and are limited to membranes which extend between the diverging
+digits of the hand and foot, forming webs as fully developed as in the
+foot of a swimming bird. As these frogs leap, the membranes are expanded
+and help to support the weight of the body, so that the animal descends
+more easily as it moves from branch to branch. There is no evidence that
+the bones of the digits ever became elongated like the fin rays of the
+flying fish or the wing bones of a Bat; but the web suggests the basis
+of such a wing, and the possibilities under which wings may first
+originate, by elongation of the bones of a webbed hand like that of a
+Flying Frog.
+
+
+FLYING LIZARDS
+
+  [Illustration: FIG. 7.  THE FLYING DRAGON, DRACO
+
+  Forming a parachute by means of the extended ribs]
+
+The Reptilia in their several orders are remarkable for absence of any
+modification of the arms which might suggest a capacity for acquiring
+wings, as being latent in their organisation. Crocodiles, Tortoises, and
+Serpents are alike of the earth, and not of the air. But among Lizards
+there are small groups of animals in which a limited capacity for
+movement through the air is developed. It is best known in the family of
+small lizards named Dragons, represented typically by the species _Draco
+volans_ found in the Oriental region of the East Indies and Malay
+Archipelago.
+
+The organ of flight is produced in an unexpected way, by means of the
+ribs instead of the limbs. The ribs extend outward as far as the arms
+can stretch, and the first five or six are prolonged beyond the body so
+as to spread a fold of skin on each side between the arm and the leg.
+The membrane admits of some movement with the ribs. This arrangement
+forms a parachute, which enables the animal to move rapidly among
+branches of trees, extending the structure at will, so that it is used
+with rapidity too quick to be followed by the eye, as it leaps through
+considerable distances.
+
+A less singular aid to movement in the air is found in some of the
+lizards termed Geckos. The so-called Flying Gecko (_Platydactylus
+homalocephalus_) has a fringe unconnected with ribs, which extends
+laterally on the sides of the body and tail, as well as at the back and
+front of the fore and hind limbs, and between the digits, where the web
+is sometimes almost as well developed as among Tree Frogs. This is
+essentially a lateral horizontal frill, extending round the body. Its
+chief interest is in the circumstance that it includes a membrane which
+extends between the wrist bones and the shoulder on the front of the
+arm. That is the only part of the fringe which represents the wing
+membrane of a bird. The fossil flying reptiles have not only that
+membrane, but the lateral membranes at the sides of the body and behind
+the arms.
+
+Other lizards have the skin developed in the direction of the
+circumference of the body. In the Australian Chlamydosaurus it forms an
+immense frill round the neck like a mediaeval collar. But though such an
+adornment might break a fall, it could not be regarded as an organ of
+flight.
+
+
+FLYING BIRDS
+
+  [Illustration: FIG. 8.  POSITION OF BIRDS IN FLIGHT]
+
+The wings of birds, when they are developed so as to minister to flight,
+are all made upon one plan; but as examples of the variation which the
+organs contributing to make the fore limb manifest, I may instance the
+short swimming limb of the Penguin, the practically useless rudiment of
+a wing found in the Ostrich or Kiwi, and the fully developed wing of the
+Pigeon. The wings of birds obtain an extensive surface to support the
+animal by muscular movements of three modifications of structure. First,
+the bones of the fore limb are so shaped that they cannot, in existing
+birds, be applied to the ground for support and be used like the limbs
+of quadrupeds, and are therefore folded up at the sides of the body,
+and carried in an unused or useless state so long as the animal hops on
+the ground or walks, balancing its weight on the hind legs. Secondly,
+there are two small folds of skin, less conspicuous than those on the
+arms of Geckos; one is between the wrist bones and the shoulder, and the
+smaller hinder membrane is between the upper arm and the body. These
+membranous expansions are insignificant, and would in themselves be
+inadequate to support the body or materially assist its movements.
+Thirdly, the bird develops appendages to the skin which are familiarly
+known as feathers, and the large feathers which make the wing are
+attached to the skin covering the lower arm bone named the ulna, and the
+other bones which represent the wrist and hand. The area and form of the
+bird's wing are due to individual appendages to the skin, which are
+unknown in any other group of animals. Between the extended wing of the
+Albatross, measuring eleven feet in spread, and the condition in the
+Kiwi of New Zealand, in which the wing is vanishing, there is every
+possible variation in size and form. As a rule, the larger the animal
+the smaller is the wing area. The problem of the origin of the bird's
+wing is not to be explained by study of existing animals; for the rowing
+organ of the Penguin, which in itself would never suggest flight,
+becomes an organ of flight in other birds by the growth upon it of
+suitable feathers. Anyone who has seen the birds named Divers feeding
+under water, swimming rapidly with their wings, might never suspect that
+they were also organs of aerial flight. The Ostrich is even more
+interesting, for it has not developed flight, and still retains at the
+extremities of two of the digits the slender claws of a limb which was
+originally no wing at all, but the support of a four-footed animal (Fig.
+46, p. 130).
+
+
+FLYING MAMMALS
+
+Flight is also developed among mammals. The Insectivora include several
+interesting examples of animals which are capable of a certain motion
+through the air. In the tropical forests of the Malay Archipelago are
+animals known as Flying Squirrels, Flying Opossums, Flying Lemurs,
+Flying Foxes, in which the skin extends outward laterally from the sides
+of the body so as to connect the fore limbs with the hind limbs, and is
+also prolonged backward from the hind limbs to the tail. The four digits
+are never elongated; the bones of the fore limb are neither longer nor
+larger than those of the hind limb, and the foot terminates in five
+little claws as in other four-footed animals. This condition is adapted
+for the arboreal life which those animals live, leaping from branch to
+branch, feeding on fruits and leaves, and in some cases upon insects.
+These mammals may be compared with the Flying Geckos among reptiles in
+their parachute-like support by extension of the skin, which gives them
+one of the conditions of support which contribute to constitute flight.
+
+  [Illustration: FIG. 9.  FLYING SQUIRREL (PTEROMYS)]
+
+_Bats._--One entire order of mammals--the Bats--not only possess true
+wings, but are capable of flight which is sustained, and in some cases
+powerful. The wings are clothed with short hair like the rest of the
+body, and thus the instrument of flight is unlike that of a bird. The
+flight of a Bat differs from that of all other animals in being
+dependent upon a modification of the bones of the fore limb, which,
+without interfering with the animal's movements as a quadruped, secures
+an extension of the wing which is not inferior in area to that which the
+bird obtains by elongation of the bones of the arm and fore-arm and its
+feathers. The distinctive peculiarity of the Bat's wing is in the
+circumstance that four of the digits of the hand have their bones
+prolonged to a length which is often equal to the combined length of the
+arm and fore-arm. The bones of the digits diverge like the ribs of an
+umbrella, and between them is the wing membrane, which extends from the
+sides of the body outward, unites the fore limb with the hind limb, and
+is prolonged down the tail as in the Flying Foxes. Bats have a small
+membrane in front of the bones of the arm and fore-arm stretching
+between the shoulder and the wrist, which corresponds with the wing
+membrane of a bird; but the remainder of the membranes in Bats' wings
+are absent in birds, because their function is performed by feathers
+which give the wing its area. The elongated digits of the Bat's wing are
+folded together and carried at the sides of the body as though they were
+a few quill pens attached to its wrist, where the one digit, which is
+applied to the ground in walking, terminates in a claw.
+
+  [Illustration: FIG. 10  NEW ZEALAND BAT FLYING. BARBASTELLE WALKING]
+
+The organs which support animals in the air are thus seen to be more or
+less dissimilar in each of the great groups of animals. They fall into
+three chief types: first, the parachute; secondly, the wing due to the
+feathers appended to the skin; and thirdly, the wing formed of membrane,
+supported by enormous elongation of the small bones of the back of the
+hand and fingers. The two types of true wings are limited to birds and
+bats; and no living reptile approximates to developing such an organ of
+flight as a wing. Judged, therefore, by the method of comparing the
+anatomical structures of one animal with another, which is termed
+"comparative anatomy," the existence of flying reptiles might be
+pronounced impossible. But in the light which the revelations of geology
+afford, our convictions become tempered with modesty; and we learn that
+with Nature nothing is impossible in development of animal structure.
+
+
+
+
+CHAPTER V
+
+DISCOVERY OF THE PTERODACTYLE
+
+
+Late in the eighteenth century, in 1784, a small fossil animal with
+wings began to be known through the writings of Collini, as found in the
+white lithographic limestone of Solenhofen in Bavaria, and was regarded
+by him as a former inhabitant of the sea. The foremost naturalist of the
+time, the citizen Cuvier--for it was in the days of the French
+Republic--in 1801, in lucid language, interpreted the animal as a genus
+of Saurians. That word, so familiar at the present day, was used in the
+first half of the century to include Lizards and Crocodiles; and
+described animals akin to reptiles which were manifestly related neither
+to Serpents nor Turtles. But the term saurian is no longer in favour,
+and has faded from science, and is interesting only in ancient history
+of progress. The lizards soon became classed in close alliance with
+snakes. And the crocodiles, with the Hatteria, were united with
+chelonians. Most modern naturalists who use the term saurian still make
+it an equivalent of lizard, or an animal of the lizard kind.
+
+
+CUVIER
+
+  [Illustration: FIG. 11.  _PTERODACTYLUS LONGIROSTRIS_ (Cuvier)
+
+  The remains are preserved with the neck arched over the back, and the
+  jaws opened upward]
+
+Cuvier defined this fossil from Solenhofen as distinguished by the
+extreme elongation of the fourth digit of the hand, and from that
+character invented for the animal the name Pterodactyle. He tells us
+that its flight was not due to prolongation of the ribs, as among the
+living lizards named Dragons; or to a wing formed without the digits
+being distinguishable from each other, as among Birds; nor with only one
+digit free from the wing, as among Bats; but by having the wing
+supported mainly by a single greatly elongated digit, while all the
+others are short and terminate in claws. Cuvier described the amazing
+animal in detail, part by part; and such has been the influence of his
+clear words and fame as a great anatomist that nearly every writer in
+after-years, in French and in English, repeated Cuvier's conclusion,
+maintained to the end, that the animal is a saurian.
+
+  [Illustration: FIG. 12.  THE SKELETON OF _PTERODACTYLUS LONGIROSTRIS_
+
+  Reconstructed from the scattered bones in Fig. 14, showing the limbs
+  on the left side]
+
+Long before fashion determined, as an article of educated belief, that
+fossil animals exist chiefly to bridge over the gaps between those which
+still survive, the scientific men of Germany were inclined to see in the
+Pterodactyle such an intermediate type of life. At first Soemmerring and
+Wagler would have placed the Pterodactyle between mammals and birds.
+
+
+GOLDFUSS
+
+  [Illustration: FIG. 13.  THE _PTERODACTYLUS LONGIROSTRIS_ RESTORED
+  FROM THE REMAINS IN FIG. 11
+
+  Showing positions of the wing membranes with the animal at rest]
+
+But the accomplished naturalist Goldfuss, who described another fine
+skeleton of a Pterodactyle in 1831, saw in this flying animal an
+indication of the course taken by Nature in changing the reptilian
+organisation to that of birds and mammals. It is the first flash of
+light on a dark problem, and its brilliance of inference has never been
+equalled. Its effects were seen when Prince Charles Bonaparte, the
+eminent ornithologist, in Italy, suggested for the group the name
+Ornithosauria; when the profound anatomist de Blainville, in France,
+placed the short-tailed animal in a class between Reptiles and Birds
+named Pterodactylia; and Andreas Wagner, of Munich, who had more
+Pterodactyles to judge from than his predecessors, saw in the fossil
+animal a saurian in transition to a bird.
+
+
+VON MEYER
+
+But the German interpretation is not uniform, and Hermann von Meyer, the
+banker-naturalist of Frankfurt a./M., who made himself conversant with
+all that his predecessors knew, and enlarged knowledge of the
+Pterodactyles on the most critical facts of structure, continued to
+regard them as true reptiles, but flying reptiles. Such is the influence
+of von Meyer that all parts of the world have shown a disposition to
+reflect his opinions, especially as they practically coincide with the
+earlier teaching of Cuvier. Owen and Huxley in England, Cope and Marsh
+in America, Gaudry in France, and Zittel in Germany have all placed the
+Pterodactyles as flying reptiles. Their judgment is emphatic. But there
+is weight of competent opinion to endorse the evolutionary teaching of
+Goldfuss that they rise above reptiles. To form an independent opinion
+the modern student must examine the animals, weigh their characters bone
+by bone, familiarise himself, if possible, with some of the rocks in
+which they are found; to comprehend the conditions under which the
+fossils are preserved, which have added not a little to the interest in
+Pterodactyles, and to the difficulty of interpretation.
+
+
+GEOLOGICAL HISTORY OF PTERODACTYLES IN GERMANY
+
+We may briefly recapitulate the geological history. Those remains of
+Ornithosaurs which have been mentioned, with a multitude of others which
+are the glory of the museums of Munich, Stuttgart, Tuebingen,
+Heidelberg, Bonn, Haarlem, and London, have all been found in working
+the lithographic stone of Bavaria. The whitish yellow limestone forms
+low, flat-topped hills, now isolated from each other by natural
+denudation, which has removed the intervening rock. The stone is found
+at some distance north of the Danube, in a line due north of Augsburg,
+in the country about Pappenheim, and especially at the villages of
+Solenhofen, Eichstaedt, Kelheim, and Nusplingen. These beds belong to the
+rocks which are named White Jura limestone in Germany, which is of about
+the same geological age as the Kimeridge clay in England. Much of it
+divides into very thin layers, and in these planes of separation the
+fossils are found. They include the _Ammonites lithographicus_ and a
+multitude of marine shells, king crabs and other Crustacea, sea-urchins,
+and other fossils, showing that the deposit was formed in the sea. The
+preservation of jelly-fish, which so soon disappear when left dry on the
+beach, shows that the ancient calcareous mud had unusual power of
+preserving fossils. Into this sea, with its fishes great and small, came
+land plants from off the land, dragonflies and other insects, tortoises
+and lizards, Pterodactyles with their flying organs, and birds still
+clothed with feathers. Sometimes the wing membranes of the flying
+reptiles are found fully stretched by the wing finger, as in examples to
+be seen at Munich and in the Yale Museum in Newhaven, in America. At
+Haarlem there is an example in which the wing membrane appears to be
+folded much as in the wing of a Bat, when the animal hangs suspended,
+with the flying membrane bent into a few wide undulations.
+
+The Solenhofen Slate belongs to about the middle period of the history
+of flying reptiles, for they range through the Secondary epochs of
+geological time. Remains are recorded in Germany from the Keuper beds at
+the top of the Trias, which is the bottom division of the Secondary
+strata; and I believe I have seen fragments of their bones from the
+somewhat older Muschelkalk of Germany.
+
+
+THEIR HISTORY IN ENGLAND
+
+In England the remains are found for the first time in the Lower Lias of
+Lyme Regis, in Dorset, and the Upper Lias of Whitby, in Yorkshire. In
+Wuertemberg they occur on the same horizons. They reappear in England, in
+every subsequent age, when the conditions of the strata and their
+fossils give evidence of near proximity to land. In the Stonesfield
+Slate of Stonesfield, in Oxfordshire, the bones are found isolated, but
+indicate animals of some size, though not so large as the rare bones of
+reputed true birds which appear to have left their remains in the same
+deposit.
+
+At least two Pterodactyles are found in the Oxford clay, known from more
+or less fragmentary remains or isolated bones; just as they occur in the
+Kimeridge Clay, Purbeck Limestone, Wealden sandstones, and especially in
+newer Secondary rocks, named Gault, Upper Greensand, and Chalk, in the
+south-east of England.
+
+Owing to exceptional facilities for collecting, in consequence of the
+Cambridge Greensand being excavated for the valuable mineral phosphate
+of lime it contains, more than a thousand bones are preserved, more or
+less broken and battered, in the Woodwardian Museum of the University
+of Cambridge alone. To give some idea of their abundance, it may be
+stated that they were mostly gathered during two or three years, as a
+matter of business, by an intelligent foreman of washers of the nodules
+of phosphate of lime, which, in commerce, are named coprolites. He soon
+learned to distinguish Pterodactyle bones from other fossils by their
+texture, and learned the anatomical names of bones from specimens in the
+University Museum. This workman, Mr. Pond, employed by Mr. William
+Farren, brought together not only the best of the remains at Cambridge,
+but most of those in the museums at York and in London, and the
+thousands of less perfect specimens in public and private collections
+which passed through the present writer's hands in endeavours to secure
+for the University useful illustrations of the animal's structure. These
+fragments, among which there are few entire bones, are valuable, for
+they have afforded opportunities of examining the articular ends of
+bones in every aspect, which is not possible when similar organic
+remains are embedded in rock in their natural connexions.
+
+In England Flying Reptiles disappear with the Chalk. In that period they
+were widely distributed, being found in Bohemia, in Brazil, and Kansas
+in the United States, as well as in Kent and other parts of England.
+They attained their largest dimensions in this period of geological
+time. One imperfect fragment of a bone from the Laramie rocks of Canada
+was described, I believe, by Cope, though not identified by him as
+Ornithosaurian, and is probably newer than other remains.
+
+
+ASPECT OF PTERODACTYLES
+
+If this series of animals could all be brought together they would vary
+greatly in aspect and stature, as well as in structure. Some have the
+head enormously long, in others it is large and deep, characters which
+are shared by extinct reptiles which do not fly, and to which some birds
+may approximate; while in a few the head is small and compact, no more
+conspicuous, relatively, than the head of a Sparrow. The neck may be
+slender like that of a Heron, or strong like that of an Eagle; the back
+is always short, and the tail may be inconspicuous, or as long as the
+back and neck together. These flying reptiles frequently have the
+proportions of the limbs similar to those of a Bat, with fore legs
+strong and hind legs relatively small; while in some the limbs are as
+long, proportionately, and graceful as those of a Deer. With these
+differences in proportions of the body are associated great differences
+in the relative length of the wing and spread of the wing membranes.
+
+
+DIMENSIONS OF THE ANIMALS
+
+The dimensions of the animals have probably varied in all periods of
+geological time. The smallest, in the Lithographic Slate, are smaller
+than Sparrows, while associated with them are others in which the
+drumstick bone of the leg is eight inches long. In the Cambridge
+Greensand and Chalk imperfect specimens occur, showing that the upper
+arm bones are larger than those of an Ox. The shaft is one and a half
+inches in diameter and the ends three inches wide. Such remains may
+indicate Pterodactyles not inferior in size to the extinct Moas of New
+Zealand, but with immensely larger heads, animals far larger than birds
+of flight.
+
+The late Sir Richard Owen, on first seeing these fragmentary remains,
+said "the flying reptile with outstretched pinions must have appeared
+like the soaring Roc of Arabian romance, but with the features of
+leathern wings with crooked claws superinduced, and gaping mouth with
+threatening teeth." Eventually we shall obtain more exact ideas of their
+aspect, when the structures of the several regions of the body have been
+examined. The great dimensions of the stretch of wing, often computed at
+twenty feet in the larger examples, might lead to expectations of great
+weight of body, if it were not known that an albatross, with wings
+spreading eleven feet, only weighs about seventeen pounds.
+
+
+
+
+CHAPTER VI
+
+HOW ANIMALS ARE INTERPRETED BY THEIR BONES
+
+
+There is only one safe path which the naturalist may follow who would
+tell the story of the meaning and nature of an extinct type of animal
+life, and that is to compare it as fully as possible in its several
+bones, and as a whole, with other animals, especially with those which
+survive. It is easy to fix the place in nature of living animals and
+determine their mutual relations to each other, because all the
+organs--vital as well as locomotive--are available for comparison. On
+such evidence they are grouped together into the large divisions of
+Beasts, Birds, and Reptiles; as well as placed in smaller divisions
+termed Orders, which are based upon less important modifications of
+fundamental structures. All these characteristic organs have usually
+disappeared in the fossil. Hence a new method of study of the hard parts
+of the skeleton, which alone are preserved, is used in the endeavour to
+discover how the Flying Reptile or other extinct animal is to be
+classified, and how it acquired its characters or came into existence.
+
+
+VARIATIONS OF BONES AMONG MAMMALIA
+
+  [Illustration: FIG. 14.  THE FORE LIMB IN FOUR TYPES OF MAMMALS
+
+  Comparison of the fore limb in mammals, showing variation of form
+  of the bones with function]
+
+Resemblances and differences in the bones are easily over-estimated in
+importance as evidence of pedigree relationship. The Mammalia show, by
+means of such skeletons as are exhibited in any Natural History Museum,
+how small is the importance to be attached to even the existence of any
+group of bones in determining its grade of organisation. The whole Whale
+tribe suckle their young and conform to the distinctive characters in
+brain and lungs which mark them as being mammals. But if there is one
+part of the skeleton more than another which distinguishes the Mammalia,
+it is the girdle of bones at the hips which supports the hind limbs. It
+is characterised by the bone named the ilium being uniformly directed
+forward. Yet in the Whale tribe the hip-girdle and the hind limb which
+it usually supports are so faintly indicated as to be practically lost;
+while the fore limb becomes a paddle without distinction of digits, and
+is therefore devoid of hoofs or claws, which are usual terminations of
+the extremities in mammals. Yet this swimming paddle, with its
+ill-defined bones--sometimes astonishing in number, as well as in
+fewness of the finger bones--is represented by the burrowing fore limb
+of the Mole, which lives underground; by the elongated hoofed legs of
+the Giraffe, which lives on plains; and the extended arm and finger
+bones of the Bat, which are equally mammals with the Whale. From such
+comparison it is seen that no proportion, or form, or length, or use of
+the bones of the limbs, or even the presence of limbs, is necessarily
+characteristic of a mammal. No limitation can be placed upon the
+possible diversity of form or development of bones in unknown animals,
+when they are considered in the light of such experience of varied
+structural conditions in living members of a single class.
+
+What is true for the limbs and the bony arches which support them is
+true for the backbone also, for the ribs, and to some extent for the
+skull. The neck in the Whale is shortened almost beyond recognition. In
+the Giraffe the same seven vertebrae are elongated into a marvellous
+neck; so that in the technical definition of a mammal both are said to
+have seven neck vertebrae. Yet exceptions show a capacity for variation.
+One of the Sloths reduces the number to six, while another has nine
+vertebrae in the neck; proving that there is no necessary difference
+between a mammal and a reptile when judged by a character which is
+typically so distinctive of mammals as the number of the neck bones.
+
+The skull varies too, though to a less extent. The Great Ant-eater of
+South America is a mammal absolutely without teeth. The Porpoises have a
+simple unvarying row of conical teeth with single roots extending along
+the jaw. And the dental armature of the jaws, and relative dimensions of
+the skull bones, exhibit such diversity, in evidence of what may be
+parted with or acquired, that recognition of the many reptilian
+structures and bones in the skull of Ornithorhynchus, the Australian
+Duckbill, demonstrates that the difficulties in recognising an animal by
+its bones are real, unless we can discover the Animal Type to which the
+bones belong; and that there is very little in osteology which may not
+be lost without affecting an animal's grade of organisation.
+
+
+VARIATION IN SKIN COVERING OF MAMMALS
+
+Even the covering of the body varies in the same class, or even order of
+animals, so that the familiar growth on the skin is never its only
+possible covering. The Indian ant-eater, named Manis, which looks like a
+gigantic fir-cone, the Armadillo, which sheathes the body in rings of
+bone, bearing only a scanty development of hair, are examples of
+mammalian hair, as singular as the quills of a Porcupine, the horn of a
+Rhinoceros, or the growth of hair of varying length and stoutness on
+different parts of the body in various animals, or the imperfect
+development of hair in the marine Cetacea. Among living animals it is
+enough for practical purposes to say that a mammal is clothed with hair,
+but in a fossil state the hair must usually be lost beyond recognition
+from its fineness and shortness of growth.
+
+
+VARIATION IN SKIN COVERING OF BIRDS
+
+No Class of living animals is more homogeneous than Birds; and
+well-preserved remains prove that, at least as far back in time as the
+Upper Oolites, birds were clothed with feathers of essentially the same
+mode of growth and appearance as the feathers of living birds. There
+may, therefore, be no ground for assuming that the covering was ever
+different, though some regions of the skin are free from feathers. Yet
+the variations from fine under-down to the scale-like feathers on the
+wings of a Penguin, or the great feathers in the wings of birds of
+flight, or the double quill of the Ostrich group, are calculated to
+yield dissimilar impressions in a fossil state, even if the fine down
+would be preserved in any stratum.
+
+
+VARIATION IN THE BONES OF BIRDS
+
+Osteologically there is less variety in the skeleton of birds than in
+other great groups of animals. The existing representatives do not
+exhaust its capability for modification. The few specimens of birds
+hitherto found in the Secondary strata have rudely removed many
+differences in the bones which separated living birds from reptiles; so
+that if only the older fossil birds were known, and the Tertiary and
+living birds had not existed, a bird might have been defined as an
+animal having its jaw armed with teeth, instead of devoid of teeth; with
+vertebrae cupped at both ends, instead of with a saddle-shaped
+articulation which in front is concave from side from side, and convex
+from above downwards; in which the bones of the hand are separate, so
+that three digits terminating in claws can be applied to the ground,
+instead of the metacarpal bones being united in a solid mass with
+clawless digits; and in which the tail is elongated like the tail of a
+lizard. Yet the limits to variation are not to be formulated till Nature
+has exhausted all her resources in efforts to preserve organic types by
+adapting them to changed circumstances. Birds may be regarded
+theoretically as equally capable with mammals of parting with almost
+every distinctive structure in the skeleton by which it is best known.
+Even the living frigate bird blends the early joints of the backbone
+into a compact mass like a sacrum. The Penguin has a cup-and-ball
+articulation in the early dorsal vertebrae, with the ball in front. And
+the genus Cypselus has the upper arm bone almost as broad as long,
+unlike the bird type. Such examples prove that we are apt to accept the
+predominant structures in an animal type as though they were universal,
+and forget that inferences based, like those of early investigators, on
+limited materials may be re-examined with advantage.
+
+
+VARIATION IN THE BONES OF REPTILES
+
+The true Reptilia, notwithstanding some strong resemblances to Birds in
+technical characters of the skeleton, display among their surviving
+representatives an astonishing diversity in the bony framework of the
+body, exceeding that of the mammalia. This unlooked-for capacity for
+varying the plan of construction of the skeleton is in harmony with the
+diversity of structure in groups of extinct animals to which the name
+reptiles has also been given. The interval in form is so vast between
+Serpent and Tortoise, and so considerable in structure of the skeleton
+between these and the several groups of Lizards, Crocodiles, and
+Hatteria, that any other diversity could not be more surprising. And the
+inference is reasonable that just as mammals live in the air, in the
+sea, on the earth, and burrow under the earth, similar modes of
+existence might be expected for birds and reptiles, though no bird is
+yet known to have put on the aspect of a fish, and no reptiles have been
+discovered which roamed in herds like antelopes, or lived in the air
+like birds or bats, unless these fossil flying animals prove on
+examination to justify the name by which they are known.
+
+Comparative study of structure in this way demolishes the prejudice,
+born of experience of the life which now remains on earth, that the
+ideas of Reptile and of Flight are incongruous, and not to be combined
+in one animal. The comparative study of the parts of animals does not
+leave the student in a chaos of possibilities, but teaches us that
+organic structures, which mark the grades of life, have only a limited
+scope of change; while Nature flings away every part of the skeleton
+which is not vital, or changes its form with altering circumstances of
+existence, enforced by revolutions of the Earth's surface in geological
+time, in her efforts to save organisms from extinction and pass the
+grade of life onward to a later age.
+
+The bones are only of value to the naturalist as symbols, inherited or
+acquired, and vary in value as evidence of the nature and association of
+those vital organs which differentiate the great groups of the
+vertebrata.
+
+These distinctive structures, which separate Mammals, Birds, and
+Reptiles, are sometimes demonstrated by the impress of their existence
+left on the bones; or sometimes they may be inferred from the characters
+of the skeleton as a whole.
+
+
+
+
+CHAPTER VII
+
+INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS
+
+
+THE ORGANS WHICH FIX AN ANIMAL'S PLACE IN NATURE
+
+We shall endeavour to ascertain what marks of its grade of organisation
+the Pterodactyle has to show. The organs which are capable of modifying
+the bones are probably limited to the kidneys, the brain, and the organs
+of respiration. It may be sufficient to examine the latter two.
+
+
+PNEUMATIC FORAMINA IN PTERODACTYLES
+
+  [Illustration: FIG. 15.  HEAD OF THE HUMERUS OF THE PTERODACTYLE
+  ORNITHOCHEIRUS
+
+  Showing position of the pneumatic foramen on the ulnar side of the
+  bone as in a bird]
+
+Hermann von Meyer, the historian of the Ornithosaurs of the Lithographic
+Slate, as early as 1837 described some Pterodactyle bones from the Lias
+of Franconia, which showed that air was admitted into the interior of
+the bones by apertures near their extremities, which, from this
+circumstance, are known as pneumatic foramina. He drew the inference,
+naturally enough, that such a structure is absolute proof that the
+Pterodactyle was a flying animal. It was not quite the right form in
+which the conclusion should have been stated, because the Ostrich and
+other birds which do not fly have the principal bones pneumatic.
+Afterwards, in 1859, the larger bones which Professor Sedgwick, of
+Cambridge, transmitted to Sir Richard Owen established this condition as
+characteristic of the Flying Reptiles of the Cambridge Greensand. It was
+thus found as a distinctive structure of the bones both at the beginning
+and the close of the geological history of these animals. Von Meyer
+remarks that the supposition readily follows that in the respiratory
+process there was some similarity between Pterodactyles and Birds. This
+cautious statement may perhaps be due to the circumstance that in many
+animals air cavities are developed in the skull without being connected
+with organs of respiration. It is well known that the bulk of the
+Elephant's head is due to the brain cavity being protected with an
+envelope formed of large air cells. Small air cells are seen in the
+skulls of oxen, pigs, and many other mammals, as well as in the human
+forehead. The head of a bird like the Owl owes something of its imposing
+appearance to the way in which its mass is enlarged by the dense
+covering of air cells in the bones above the brain, like that seen in
+some Cretaceous Pterodactyles. Nor are the skulls of Crocodiles or
+Tortoises exceptions to the general rule that an animal's head bones may
+be pneumatic without implying a pneumatic prolongation of air from the
+lungs. The mere presence of air cells without specification of the
+region of the skeleton in which they occur is not remarkable. The holes
+by which air enters the bones are usually much larger in Pterodactyles
+than in Birds, but the entrance to the air cell prolonged into the bones
+is the same in form and position in both groups. So far as can be judged
+by this character, there is no difference between them. The importance
+of the comparison can only be appreciated by examining the bones side by
+side. In the upper arm bone of a bird, on what is known as the ulnar
+border, near to the shoulder joint, and on the side nearest to it, is
+the entrance to the air cell in the humerus. In the Pterodactyle the
+corresponding foramen has the same position, form, and size, and is not
+one large hole, but a reticulation of small perforations, one beyond
+another, exactly such as are seen in the entrance to the air cell in the
+bone of a bird, in which the pneumatic character is found. For it is not
+every bird of flight which has this pneumatic condition of the bones;
+and Dr. Crisp stated that quite a number of birds--the Swallow, Martin,
+Snipe, Canary, Wood-wren and Willow-wren, Whinchat, Glossy-starling,
+Spotted-fly-catcher, and Black-headed Bunting--have no air in their
+bones. And it is well known that in many birds, especially water birds,
+it is only the upper bones of the limbs which are pneumatic, while the
+smaller bones retain the marrow.
+
+
+LUNGS AND AIR CELLS
+
+  [Illustration: FIG. 16.  LUNGS OF THE BIRD APTERYX PARTLY OPENED ON
+  THE RIGHT-HAND SIDE
+
+  The circles are openings of the bronchial tubes on the surface of the
+  lung. The notches on the inner edges of the lungs are impressions of
+  the ribs (After R. Owen)]
+
+  [Illustration: FIG. 17.  THE BODY OF AN OSTRICH LAID OPEN TO SHOW THE
+  AIR CELLS WHICH EXTEND THROUGH ITS LENGTH (After Georges Roche)]
+
+It may be well to remember that the lungs of a bird are differently
+conditioned from those of any other animal. Instead of hanging freely
+suspended in the cone-shaped chamber of the thorax formed by the ribs
+and sternum, they are firmly fixed on each side, so that the ribs deeply
+indent them and hold them in place. The lungs have the usual internal
+structure, being made up of branching cells. The chief peculiarity
+consists in the way in which the air passes not only into them, but
+through them. The air tube of the throat of a bird, unlike that of a
+man, has the organ of voice, not at the upper end in the form of a
+larynx, but at the lower end, forming what is termed a syrinx. There is
+no evidence of this in a fossil state, although in a few birds the rings
+of the trachaea become ossified, and are preserved. But below the syrinx
+the trachaea divides into two bronchi, tubes which carry the ringed
+character into the lungs for some distance, and these give off branches
+termed bronchial tubes, the finer subdivisions from which, in their
+clustered minute branching sacs, make up the substance of the lung.
+There is nothing exceptional in that. But towards the outer or middle
+part of the ventral or under surface of the lungs, four or five rounded
+openings are seen on each side. Each of these openings resembles the
+entrance of the air cell into a bone, since it displays several smaller
+openings which lead to it. Each opening from the lung leads to an air
+cell. Those cells may be regarded as the blowing out of the membrane
+which covers the lungs into a film which holds air like a mass of soap
+bubbles, until the whole cavity of the body of a bird from neck to tail
+is occupied by sacculated air cells, commonly ten in number, five on
+each side, though two frequently blend at the base of the neck in the
+region of the #V#-shaped bone named the clavicle or furculum, popularly
+known as the merry-thought. Most people have seen some at least of
+these semi-transparent bladder-like air cells beneath the skin in the
+abdominal region of a fowl. The cells have names from their positions,
+and on each side one is abdominal, two are thoracic, one clavicular, and
+one cervical, which last is at the base of the neck. The clavicular and
+abdominal air cells are perhaps the most interesting. The air cell
+termed clavicular sends a process outward towards the arm, along with
+the blood vessels which supply the arm. Thus this air cell, entering the
+region of the axilla or arm-pit, enters the upper arm bone usually on
+its under side, close to the articular head of the humerus, and in the
+same way the air may pass from bone to bone through every bone in the
+fore limb. The hind limbs similarly receive air from the abdominal air
+cell, which supplies the femur and other bones of the leg, the sacrum,
+and the tail. But the joints of the backbone in front of the sacrum
+receive their air from the cervical air sac. The air cells are not
+limited to the bones, but ramify through the body, and in some cases
+extend among the muscles. A bird may be said to breathe not only with
+its lungs, but with its whole body. And it is even affirmed that
+respiration has been carried on through a broken arm bone when the
+throat was closed, and the bird under water.
+
+Birds differ greatly in the extent to which the aircell system prolonged
+from the lungs is developed, some having the air absent from every bone,
+while others, like the Swift, are reputed to have air in every bone of
+the body.
+
+Comparison shows that in so far as the bones are the same in Bird and
+Ornithosaur, the evidence of the air cells entering them extends to
+resemblance, if not coincidence, in every detail. No living group of
+animals except birds has pneumatic limb bones, in relation to the lungs;
+so that it is reasonable to conclude that the identical structures in
+the bones were due to the same cause in both the living and extinct
+groups of animals. It is impossible to say that the lungs were identical
+in Birds and Pterodactyles, but so far as evidence goes, there is no
+ground for supposing them to have been different.
+
+
+THE LUNGS OF REPTILES
+
+  [Illustration: FIG. 18.  THE SIDE OF THE BODY OF A CHAMELEON
+
+  Ribs removed to show the sacculate branched form of the lung]
+
+There is nothing comparable to birds, either in the lungs of living
+reptiles or in their relation to the bones. The Chameleon is remarkable
+in that the lung is not a simple bladder prolonged through the whole
+length of the body cavity, as in a serpent, but it develops a number of
+large lateral branches visible when the body is laid open. Except near
+the trachaea, where the tissue has the usual density of a lizard lung,
+the air cell is scarcely more complicated than the air bladder of a
+fish, and does not enter into any bone of the skeleton. And although
+many fishes like the Loach have the swim bladder surrounded by bone
+connected with the head, it offers no analogy to the pneumatic condition
+of the bones in the Pterodactyle.
+
+
+THE FORM OF THE BRAIN CAVITY
+
+  [Illustration: FIG. 19.  THE FORM OF THE BRAIN]
+
+But the identity of the pneumatic foramina in Birds and Flying Reptiles
+is not a character which stands by itself as evidence of organisation,
+for a mould of the form of the brain case contributes evidence of
+another structural condition which throws some light on the nature of
+Ornithosaurs. Among many of the lower animals, such as turtles, the
+brain does not fill the chamber in the dry skull, in which the same
+bones are found as are moulded upon the brain in higher animals. For the
+brain case in such reptiles is commonly an envelope of cartilage, as
+among certain fishes; and except among serpents, the Ophidia, the bones
+do not completely close the reptilian brain case in front. The brain
+fills the brain case completely among birds. A mould from its interior
+is almost as definite in displaying the several parts of which it is
+formed as the actual brain would be. And the chief regions of the brain
+in a bird--cerebrum, optic lobes, cerebellum--show singularly little
+variation in proportion or position. The essential fact in a bird's
+brain, which separates it absolutely from all other animals, is that the
+pair of nerve masses known as the optic lobes are thrust out at the
+sides, so that the large cerebral hemispheres extend partly over them as
+they extend between them to abut against the cerebellum. This remarkable
+condition has no parallel among other vertebrate animals. In Fishes,
+Amphibians, Reptiles, and Mammals the linear succession of the several
+parts of the brain is never departed from; and any appearance of
+variation from it among mammals is more apparent than real, for the
+linear succession may be seen in the young calf till the cerebral
+hemispheres grow upward and lop backward, so as to hide the relatively
+small brain masses which correspond to the optic lobes of reptiles,
+extending over these corpora-quadrigemina, as they are named, so as to
+cover more or less of the mass of the cerebellum. From these conditions
+of the brain and skull, it would not be possible to mistake a mould
+from the brain case of a bird for that of a reptile, though in some
+conditions of preservation it is conceivable that the mould of the brain
+of a bird might be distinguished with difficulty from that of the brain
+in the lowest mammals. Taken by itself, the avian form of brain in an
+animal would be as good evidence that its grade of organisation was that
+of a bird as could be offered.
+
+
+THE BRAIN IN SOLENHOFEN PTERODACTYLES
+
+It happens that moulds of the brain of Pterodactyles, more or less
+complete, are met with of all geological ages--Liassic, Oolitic, and
+Cretaceous. The Solenhofen Slate is the only deposit in Europe in which
+Pterodactyle skulls can be said to be fairly numerous. They commonly
+have the bones so thin as to show the form of the upper surface of the
+mould of the brain, or the bones have scaled off the mould, or remain in
+the counterpart slab of stone, so as to lay bare the shape of the brain
+mass.
+
+In the Museum at Heidelberg a skull of this kind is seen in the
+long-tailed genus of Pterodactyles named Rhamphorhynchus. It shows the
+large rounded cerebral hemispheres, which extend in front of cerebral
+masses of smaller size a little below them in position, which perhaps
+are as like the brain of a monotreme mammal as a bird.
+
+The short-tailed Pterodactylus described by Cuvier has the cerebral
+hemispheres very similar to those of a bird, but the relations of the
+hinder parts of the brain to each other are less clear.
+
+The first specimen to show the back of the brain was found by Mr. John
+Francis Walker, M.A., in the Cambridge Greensand. I was able to remove
+the thick covering of cellular bone which originally extended above it,
+and thus expose evidence that in the mutual relations of the fore and
+hind parts of the brain bird and ornithosaur were practically identical.
+Another Cambridge Greensand skull showed that in the genus
+Ornithocheirus the optic lobes of the brain are developed laterally, as
+in birds. That skull was isolated and imperfect. But about the same time
+the late Rev. W. Fox, of Brixton, in the Isle of Wight, obtained from
+Wealden beds another skull, with jaws, teeth, and the principal bones of
+the skeleton, which showed that the Wealden Pterodactyle Ornithodesmus
+had a similar and bird-like brain. In 1888 Mr. E. T. Newton, F.R.S.,
+obtained a skull from the Upper Lias, uncrushed and free from
+distortion. This made known the natural mould of the brain, which shows
+the cerebral hemispheres, optic lobes, and cerebellum more distinctly
+than in the specimens previously known. In some respects it recalls the
+Heidelberg brain of Rhamphorhynchus in the apparently transverse
+subdivision of the optic lobes, but it is unmistakably bird-like, and
+quite unlike any reptile.
+
+
+IMPORTANCE OF THE BRAIN AND BREATHING ORGANS
+
+So far as the evidence goes, it appears that these fossil flying animals
+show no substantial differences from birds, either in the mould of the
+brain or the impress of the breathing organs upon the bones. These
+approximations to birds of the nervous and respiratory systems, which
+are beyond question two of the most important of the vital organs of an
+animal, and distinctive beyond all others of birds, place the
+naturalist in a singular dilemma. He must elect whether he will trust
+his interpretation to the soft organs, which among existing animals
+never vary their type in the great classes of vertebrate animals, and on
+which the animal is defined as something distinct from its envelope the
+skeleton and its appendages the limbs, or whether he will ignore them.
+The answer must choose substantially between belief that the existing
+order of Nature gives warrant for believing that these vital
+characteristics which have been discussed might equally coexist with the
+skeleton of a mammal or a reptile, as with that of a bird, for which
+there is no particle of evidence in existing life. Or, as an
+alternative, the fact must be accepted that birds only have such vital
+organs as are here found, and therefore the skeleton, that may be
+associated with them, cannot affect the reference of the type to the
+same division of the animal kingdom as birds. The decision need not be
+made without further consideration. But brain and breathing organs of
+the avian type are structures of a different order of stability in most
+animals from the bones, which vary to a remarkable extent in almost
+every ordinal group of animals.
+
+
+TEMPERATURE OF THE BLOOD
+
+The organs of circulation and digestion are necessarily unknown. There
+are reasons why the blood may have been hot, such as the evidences from
+the wings of exceptional activity; though the temperature depends more
+upon the amount of blood in the body than upon the apparatus by which it
+is distributed. We speak of a Crocodile as cold-blooded, yet it is an
+animal with a four-chambered heart not incomparable with that of a
+bird. On the other hand, the Tunny, a sort of giant Mackerel, is a fish
+with a three-chambered heart, only breathing the air dissolved in water,
+which has blood as warm as a mammal, its temperature being compared to
+that of a pig. Several fishes have blood as warm as that of Manis, the
+scaly ant-eater; and many birds have hotter blood than mammals. The term
+"hot-blooded," as distinct from "cold-blooded," applied to animals, is
+relative to the arbitrary human standard of experience, and expresses no
+more than the circumstance that mammals and birds are warmer animals
+than reptiles and fishes.
+
+The exceptional temperature of the Flying Fish has led to a vague
+impression that physical activity and its effect upon the amount of
+blood which vigour of movement circulates, are more important in raising
+an animal's temperature than possession of the circulatory organs
+commonly associated with hot blood, which drive the blood in distinct
+courses through the body and breathing organs. Yet the kind of heart
+which is always associated with vital structures such as Pterodactyles
+are inferred to have possessed from the brain mould and the pneumatic
+foramina in the bones, is the four-chambered heart of the bird and the
+mammal. Considering these organs alone--of which the fossil bones yield
+evidence--we might anticipate, by the law of known association of
+structures, that nothing distinctly reptilian existed in the other soft
+part of the vital organisation, because there is no evidence in favour
+of or against such a possibility.
+
+
+
+
+CHAPTER VIII
+
+THE PLAN OF THE SKELETON
+
+
+While these animals are incontestably nearer to birds than to any other
+animals in their plan of organisation, thus far no proof has been found
+that they are birds, or can be included in the same division of
+vertebrate life with feathered animals. It is one of the oldest and
+soundest teachings of Linnaeus that a bird is known by its feathers; and
+the record is a blank as to any covering to the skin in Pterodactyles.
+There is the strongest probability against feathers having existed such
+as are known in the Archaeopteryx, because every Solenhofen Ornithosaur
+appears to have the body devoid of visible or preservable covering,
+while the two birds known from the Solenhofen Slate deposit are well
+clothed with feathers in perfect preservation. We turn from the skin to
+the skeleton.
+
+The plan on which the skeleton is constructed remains as evidence of the
+animal's place in nature, which is capable of affording demonstration on
+which absolute reliance would have been placed, if the brain and
+pneumatic foramina had remained undiscovered. With the entire skeleton
+before us, it is inconceivable that anatomical science should fail to
+discover the true nature of the animal to which it belonged, by the
+method of comparing one animal with another. There is no lack of this
+kind of evidence of Pterodactyles in the three or four scores of
+skeletons, and thousands of isolated or associated bones, preserved in
+the public museums of Europe and America.
+
+I may recall the circumstance that the discovery of skeletons of fossil
+animals has occasionally followed upon the interpretation of a single
+fragment, from which the animal has been well defined, and sometimes
+accurately drawn, before it was ever seen. So I propose, before drawing
+any conclusions from the skeletons in the entirety of their
+construction, to examine them bone by bone, and region by region, for
+evidence that will manifest the nature of this brood of Dragons. Their
+living kindred, and perhaps their extinct allies, assembled as a jury,
+may be able to determine whether resemblances exist between them, and
+whether such similarity between the bones as exists is a common
+inheritance, or is a common acquisition due to similar ways of life, and
+no evidence of the grade of the organism among vertebrate animals.
+
+The bones of these Ornithosaurs, when found isolated, first have to be
+separated from the organisms with which they are associated and mixed in
+the geological strata. This discrimination is accomplished in the first
+instance by means of the texture of the surface. The density and polish
+of the bones is even more marked than in the bones of birds, and is
+usually associated with a peculiar thinness of substance of the bone,
+which is comparable to the condition in a bird, though usually a little
+stouter, so that the bones resist crushing better. Pterodactyle bones
+in many instances are recognised by their straightness and comparatively
+uniform dimensions, due to the exceptional number of long bones which
+enter into the structure of the wing as compared with birds. When the
+bones are unerringly determined as Ornithosaurian, they are placed side
+by side with all the bones which are most like them, till, judged by the
+standard of the structures of living animals, the fossil is found to
+show a composite construction as though it were not one animal but many,
+while its individual bones often show equally composite characters, as
+though parts of the corresponding bone in several animals had been
+cunningly fitted together and moulded into shape.
+
+
+THE PLAN OF THE HEAD IN ORNITHOSAURS
+
+The head is always the most instructive part of an animal. It is less
+than an inch long in the small Solenhofen skeleton named _Pterodactylus
+brevirostris_, and is said to be three feet nine inches long in the
+toothless Pterodactyle Ornithostoma from the Chalk of Kansas. Most of
+these animals have a long, slender, conical form of head, tapering to
+the point like the beak of a Heron, forming a long triangle when seen
+from above or from the side. Sometimes the head is depressed in front,
+with the beak flattened or rounded as in a Duck or Goose, and
+occasionally in some Wealden and Greensand species the jaws are
+truncated in front in a massive snout quite unlike any bird. The back of
+the head is sometimes rounded as among birds, showing a smooth
+pear-shaped posterior convexity in the region of the brain. Sometimes
+the back of the head is square and vertical or oblique. Occasionally a
+great crest of cellular tissue is extended backward from above the
+brain case over the spines of the neck bones.
+
+There are always from two to four lateral openings in the skull. First,
+the nostril is nearest to the extremity of the beak. Secondly, the
+orbits of the eyes are placed far backward. These two openings are
+always present. The nostril may incline upward. The orbits of the eyes
+are usually lateral, though their upper borders sometimes closely
+approximate, as in the woodpecker-like types from the Solenhofen Slate
+named _Pterodactylus Kochi_, now separated as another genus. In most
+genera there is an opening in the side of the head, between the eye hole
+and the nostril, known as the antorbital vacuity; and another opening,
+which is variable in size and known as the temporal vacuity, is placed
+behind the eye. The former is common in the skulls of birds, the latter
+is absent from all birds and found in many reptiles.
+
+The palate is usually imperfectly seen, but English and American
+specimens have shown that it has much in common with the palate in
+birds, though it varies greatly in form of the bones in representatives
+from the Lias, Oolites, and Cretaceous rocks.
+
+From the scientific aspect the relative size of the head, its form, and
+the positions and dimensions of its apertures and processes, are of
+little importance in comparison with its plan of construction, as
+evidenced by the positions and relations to each other of the bones of
+which it is formed. There usually is some difficulty in stating the
+limits of the bones of the skull, because in Pterodactyles, as among
+birds, they usually blend together, so that in the adult animal the
+sutures between the bones are commonly obliterated.
+
+Bones have relations to each other and places in the head which can only
+change as the organs with which they are associated change their
+positions. No matter what the position of a nostril may be--at the
+extremity of a long snout, as in an ant-eater, or far back at the top of
+the head in a porpoise, or at the side of the head in a bird--it is
+always bordered by substantially the same bones, which vary in length
+and size with the changing place of the nostril and the form of the
+head. Every region of the head is defined by this method of
+construction; so that eye holes and nose holes, brain case and jaw
+bones, palate and teeth, beak, and back of the skull are all instructive
+to those who seek out the life-history of these animals. We may briefly
+examine the head of an Ornithosaurian.
+
+
+BONES ABOUT THE NOSTRIL
+
+No matter what its form may be, the head of an Ornithosaur always
+terminates in front in a single bone called the intermaxillary. It sends
+a bar of bone backward above the visible nostrils, between them; and a
+bar on each side forms the margin of the jaw in which teeth are
+implanted. The bone varies in depth, length, sharpness, bluntness,
+slenderness, and massiveness. As the bone becomes long the jaw is
+compressed from side to side, and the openings of the nostrils are
+removed backward to an increasing distance from the extremity of the
+beak.
+
+The outer and hinder border of the nostril is made by another bone named
+the maxillary bone, which is usually much shorter than the premaxillary.
+It contains the hindermost teeth, which rarely differ from those in
+front, except in sometimes being smaller.
+
+The nasal bones, which always make the upper and hinder border of the
+nostrils, meet each other above them, in the middle line of the beak.
+
+  [Illustration: FIG. 20
+
+  Showing that the extremity of the jaws in Rhamphorhynchus was
+  sheathed in horn as in the giant Kingfisher, since the jaws
+  similarly gape in front.
+
+  The hyoid bones are below the lower jaw in the Pterodactyle.]
+
+The nostrils are unusually large in the Lias genus named Dimorphodon,
+and small in species of the genus Rhamphorhynchus from Solenhofen. Such
+differences result from the relative dimensions and proportions of these
+three bones which margin the nasal vacuity, and by varying growth of
+their front margins or of their hinder margins govern the form of the
+snout.
+
+The jaws are most massive in the genera known from the Wealden beds to
+the Chalk. The palatal surface is commonly flat or convex, and often
+marked by an elevated median ridge which corresponds to a groove in the
+lower jaw, though the median ridge sometimes divides the palate into two
+parallel concave channels. The jaw is margined with teeth which are
+rarely fewer than ten or more than twenty on each side. They are sharp,
+compressed from side to side, curved inward, and never have a saw-like
+edge on the back and front margins. No teeth occur upon the bones of the
+palate.
+
+In most birds there is a large vacuity in the side of the head between
+the nostril and the orbit of the eye, partly separated from it by the
+bone which carries the duct for tears named the lachrymal bone. The same
+preorbital vacuity is present in all long-tailed Pterodactyles, though
+it is either less completely defined or absent in the group with short
+tails. It affords excellent distinctive characters for defining the
+genera. In the long-tailed genus Scaphognathus from Solenhofen this
+preorbital opening is much larger than the nostril, while in Dimorphodon
+these vacuities are of about equal size. Rhamphorhynchus is
+distinguished by the small size of the antorbital vacuity, which is
+placed lower than the nostril on the side of the face. The aperture is
+always imperfectly defined in Pterodactylus, and is a relatively small
+vacuity compared with the long nostril. In Ptenodracon the antorbital
+vacuity appears to have no existence separate from the nostril which
+adjoins the eye hole. And so far as is known at present there is no
+lateral opening in advance of the eye in the skull in any Ornithosaur
+from Cretaceous rocks, though the toothless Ornithostoma is the only
+genus with the skull complete. When a separate antorbital vacuity
+exists, it is bordered by the maxillary bone in front, and by the malar
+bone behind. The prefrontal bone is at its upper angle. That bone is
+known in a separate state in reptiles and, I think, in monotreme
+mammals. Its identity is soon lost in the mammal, and its function in
+the skull is different from the corresponding bone in Pterodactyles.
+
+
+BONES ABOUT THE EYES
+
+  [Illustration: FIG. 21.  UPPER SURFACE OF SKULL OF THE HERON
+
+  Compared with the same aspect of the skull of Rhamphorhynchus]
+
+The third opening in the side of the head, counting from before
+backward, is the orbit of the eye. In this vacuity is often seen the
+sclerotic circle of overlapping bones formed in the external membrane of
+the eye, like those in nocturnal birds and some reptiles. The eye hole
+varies in form from an inverted pear-shape to an oblique or transverse
+oval, or a nearly circular outline. It is margined by the frontal bone
+above; the tear bone or lachrymal, and the malar or cheek bone in front;
+while the bones behind appear to be the quadrato-jugal and post-frontal
+bones, though the bones about the eye are somewhat differently arranged
+in different genera.
+
+The eyes were frequently, if not always, in contact with the anterior
+walls of the brain case, as in many birds, and are always far back in
+the side of the head. In Dimorphodon they are in front of the
+articulation of the lower jaw; in Rhamphorhynchus, above that
+articulation; while in Ornithostoma they are behind the articulation for
+the jaw. This change is governed by the position of the quadrate bone,
+which is vertical in the Lias genus, inclined obliquely forward in the
+fossils from the Oolites, and so much inclined in the Chalk fossil that
+the small orbit is thrown relatively further back.
+
+Thus far the chief difference in the Pterodactyle skull from that of a
+bird is in the way in which the malar arch is prolonged backward on each
+side. It is a slender bar of bone in birds, without contributing
+ascending processes to border vacuities in the side of the face, while
+in these fossil animals the lateral openings are partly separated by the
+ascending processes of these bones. This divergence from birds, in the
+malar bone entering the orbit of the eye is approximated to among
+reptiles and mammals, though the conditions, and perhaps the presence of
+a bone like the post-orbital bone, are paralleled only among Reptiles.
+The Pterodactyles differ among themselves enough for the head to make a
+near approach to Reptiles in Dimorphodon, and to Birds in
+Pterodactylus. In the Ground Hornbill and the Shoebill the lachrymal
+bones in front of the orbits of the eyes grow down to meet the malar
+bars without uniting with them. The post-frontal region also is
+prolonged downward almost as far as the malar bar, as though to show
+that a bird might have its orbital circle formed in the same way and by
+the same bones as in Pterodactylus. Cretaceous Ornithosaurs sometimes
+differ from birds apparently in admitting the quadrato-jugal bone into
+the orbit. It then becomes an expanded plate, instead of a slender bar
+as in all birds.
+
+
+THE TEMPORAL FOSSA
+
+A fourth vacuity is known as the temporal fossa. When the skull of such
+a mammal as a Rabbit, or Sheep, is seen from above, there is a vacuity
+behind the orbits for the eyes, which in life is occupied by the muscles
+which work the lower jaw. It is made by the malar bone extending from
+the back of the orbit and the process of bone, called the zygomatic
+process, extending forward from the articulation of the jaw, which
+arches out to meet the malar bone.
+
+In birds there is no conspicuous temporal fossa, because the malar bar
+is a slender rod of bone in a line with the lower end of the quadrate
+bone.
+
+Reptile skulls have sometimes one temporal vacuity on each side, as
+among tortoises, formed by a single lateral bar. These vacuities, which
+correspond to those of mammals in position, are seen from the top of the
+head, as lateral vacuities behind the orbits of the eyes, and are termed
+superior temporal vacuities. In addition to these there is often in
+other reptiles a lateral opening behind the eye, termed the inferior
+temporal vacuity, seen in Crocodiles, in Hatteria, and in Lizards; and
+in such skulls there are two temporal bars seen in side view,
+distinguished as superior and inferior. The superior arch always
+includes the squamosal bone, which is at the back of the single bar in
+mammals. The lower arch includes the malar bone, which is in front in
+the single arch of mammals. The circumstance that both these arches are
+connected with the quadrate bone makes the double temporal arch
+eminently reptilian.
+
+In Ornithosaurs the lateral temporal vacuity varies from a typically
+reptilian condition to one which, without becoming avian, approaches the
+bird type. In skulls from the Lias, Dimorphodon and Campylognathus,
+there is a close parallel to the living New Zealand reptile Hatteria, in
+the vertical position of the quadrate bone and in the large size of the
+vacuity behind and below the eye, which extends nearly the height of the
+skull. In the species of the genus Pterodactylus, the forward
+inclination of the quadrate bone recalls the Curlew, Snipe, and other
+birds. The back of the head is rounded, and the squamosal bone, which
+appears to enter into the wall of the brain case as in birds and
+mammals, is produced more outward than in birds, but less than in
+mammals, so as to contribute a little to the arch which is in the
+position of the post-frontal bone of reptiles. It is triangular, and
+stretches from the outer angle of the frontal bone at the back of the
+orbit to the squamosal behind, where it also meets the quadrate bone.
+Its third lower branch meets the quadratojugal, which rests upon the
+front of the quadrate bone, as in Iguanodon, and is unlike Dimorphodon
+in its connexions. In that genus the supra-temporal bone, or
+post-orbital bone, appears to rest upon the post-frontal and connect it
+with the quadrato-jugal. In Dimorphodon the malar bone is entirely
+removed from the quadrate, but in Pterodactylus it meets its articular
+end. Between the post-frontal bone above and the quadrato-jugal bone
+below is a small lunate opening, which represents the lateral temporal
+vacuity; and so far, this is a reptilian character. But if the thin
+post-frontal bone were absorbed, Pterodactylus would resemble birds.
+There is no evidence that the quadrate bone is free in any Ornithosaurs,
+as it is in all birds, while in Dimorphodon it unites by suture with the
+squamosal bone. In Ornithostoma the lateral temporal vacuity is little
+more than a slit between the quadrate bone below, the quadrato-jugal in
+front, and what may be the post-frontal bone behind (see Fig. 2, p. 12).
+
+
+BONES ABOUT THE BRAIN
+
+The bones containing the brain appear to be the same as form the brain
+case in birds. The form of the back of the skull varies in two ways.
+First it may be flat above and flat at the back, when the back of the
+head appears to be square. This condition is seen in all the long-tailed
+genera, such as Campylognathus from the Lias and Rhamphorhynchus, and is
+associated with a high position for the upper temporal bar. Secondly,
+the back of the head may be rounded convexly, both above and behind.
+That condition is seen in the short-tailed genera, such as
+Pterodactylus. But in the large Cretaceous types, such as Ornithocheirus
+and Ornithostoma, the superior longitudinal ridge which runs back in
+the middle line of the face becomes elevated and compressed from side to
+side at the back of the head as a narrow deep crest, prolonged backward
+over the neck vertebrae for some inches of length. All these three types
+are paralleled more or less in birds which have the back of the head
+square like the Heron, or rounded like the Woodpecker; or crested,
+though the crest of the Cormorant is not quite identical with
+Ornithocheirus, being a distinct bone at the back of the head in the
+bird which never blends with the skull. In so far as the crest is
+reptilian it suggests the remarkable crest of the Chameleon. In the
+structure of the back of the skull the bones are a modification of the
+reptilian type of Hatteria in the Lias genus Campylognathus, but the
+reptilian characters appear to be lost in the less perfectly preserved
+skulls of Cretaceous genera.
+
+The palate is well known in the chief groups of Ornithosaurs, such as
+Campylognathus, Scaphognathus, and Cycnorhamphus.
+
+Mr. E. T. Newton, F.R.S., has shown that in the English skull from the
+Lias of Whitby, the forms of the bones are similar to the palate in
+birds and unlike the conditions in reptiles. There is one feature,
+however, which may indicate a resemblance to Dicynodon and other fossil
+reptiles from South Africa. A slender bone extends from the base of the
+brain case, named the basi-sphenoid bone, outward and forward to the
+inner margin of the quadrate bone (Fig. 22). A bone is found thus placed
+in those South African Reptiles, which show many resemblances to the
+Monotreme and Marsupial Mammals. It is not an ordinary element of the
+skeleton and is unknown in living animals of any kind in that position.
+It has been thought possible that it may represent one of the bones
+which among mammals are diminutive and are included in the internal ear.
+The resemblance may have some interest hereafter, as helping to show
+that certain affinities of the Ornithosaurs may lie outside the groups
+of existing reptiles. Instead of being directed transversely outward, as
+in the palatal region of _Dicynodon lacerticeps_, they diverge outward
+and forward to the inner border of the articulation for the lower jaw
+which is upon the quadrate bone.
+
+  [Illustration: FIG. 22]
+
+
+BONES OF THE PALATE
+
+There is a pair of bones which extend forward from these inner articular
+borders of the quadrate bones, and converge in a long #V#-shape till
+they merge in the hard palate formed by the bones of the front of the
+beak, named intermaxillary and maxillary bones. The limits of the bones
+of the palate are not distinct, but there can be no doubt that the
+front of the #V# is the bone named vomer, that the palatine bones are at
+its sides, and that its hinder parts are the pterygoid bones as in
+birds. There is a long, wide, four-sided, open space in the middle of
+the palate, between the vomer and the basi-sphenoid bone, unlike
+anything in birds or other animals.
+
+Professor Marsh, in a figure of the palate in the great skull of the
+toothless Pterodactyle named Ornithostoma (Pteranodon), from the Chalk
+of Kansas, found a large oval vacuity in this region of the palate. In
+that genus the pterygoid bones meet each other between the quadrate
+bones as in Dicynodon (Fig. 73, p. 182). Hence the great palatal vacuity
+here seen in the Ornithosaur is paralleled by the small vacuity in the
+South African reptile, which is sometimes distinct and sometimes partly
+separated from the anterior part of the vacuity which forms the openings
+of the nostrils on the palate.
+
+The Solenhofen skulls which give any evidence of the palate are exposed
+in side view only, and the bones, imperfectly seen through the lateral
+vacuities, are displaced by crushing. They include long strips like the
+vomerine bones in the Lias fossil, and they diverge in the same way as
+they extend back to the quadrate bones. The oblique division into vomer
+in front and pterygoid bone behind is shown by Goldfuss in his original
+figure of Scaphognathus. Thus there is some reason for believing that
+all Ornithosaurs have the palate formed upon the same general plan,
+which is on the whole peculiar to the group, especially in not having
+the palatal openings of the nares divided in the middle line. It would
+appear probable that the short-tailed animals have the pterygoid bones
+meeting in the middle line and triangular; and that they are slender
+rods entirely separate from each other in the long-tailed genera.
+
+
+THE TEETH
+
+The teeth are all of pointed, elongated shape, without distinction into
+the kinds seen in most mammals and named incisors, canines, and
+grinders. They are organs for grasping, like the teeth of the
+fish-eating Crocodile of India, and are not unlike the simple teeth of
+some Porpoises. They are often implanted in oblique oval sockets with
+raised borders, usually at some distance apart from each other, and have
+the crown pointed, flattened more on the outer side than on the inner
+side, usually directed forward and curved inward. As in many extinct
+animals allied to existing reptiles, the teeth are reproduced by germs,
+which originate on the inner side of the root and grow till they
+gradually absorb the substance of the old tooth, forming a new one in
+its place. Frequently in Solenhofen genera, like Scaphognathus and
+Pterodactylus, the successional tooth is seen in the jaw on the hinder
+border of the tooth in use. There is some variation in the character of
+bluntness or sharpness of the crowns in the different genera, and in
+their size.
+
+The name Dimorphodon, given to the animal from the Lias of Lyme Regis,
+expresses the fact that the teeth are of two kinds. In the front of the
+jaw three or four large long teeth are found in the intermaxillary bone
+on each side, as in some Plesiosaurs, while the teeth found further back
+in the maxillary bone are smaller, and directed more vertically
+downward. This difference is more marked in the lower jaw than in the
+upper jaw. In Rhamphorhynchus the teeth are all relatively long and
+large, and directed obliquely forward, but absent from the extremities
+of the beak, as in the German genus from the Lias named Dorygnathus, in
+which the bone of the lower jaw (which alone is known) terminates in a
+compressed spear. In Scaphognathus the teeth are few, more vertical, and
+do not extend backward so far as in Rhamphorhynchus, but are carried
+forward to the extremity of the blunt, deep jaw.
+
+In the short-tailed Pterodactyles the teeth are smaller, shorter, wider
+at the base of the crown, closer together, and do not extend so far
+backward in the jaw. In Ornithocheirus two teeth always project forward
+from the front of the jaw. Ornithostoma is toothless.
+
+
+SUPPOSED HORNY BEAK
+
+Sometimes a horny covering has been suggested for the beak, like that
+seen in birds or turtles, but no such structure has been preserved, even
+in the Solenhofen Slate, in which such a structure would seem as likely
+to be preserved as a wing membrane, though there is one doubtful
+exception. There are marks of fine blood vessels on some of the jaws,
+indicating a tough covering to the bone. In Rhamphorhynchus the jaws
+appear to gape towards their extremities as though the interspace had
+originally been occupied by organic substance like a horny beak.
+
+
+LOWER JAW
+
+The lower jaw varies in relative length with the vertical or horizontal
+position of the quadrate bone in the skull. In Dimorphodon the jaw is as
+long as the skull; but in the genera from the Oolitic rocks the
+mandible is somewhat shorter, and in Ornithostoma the discrepancy
+reaches its maximum. The hinder part of the jaw is never prolonged
+backward much beyond the articulation, differing in this respect from
+Crocodiles and Plesiosaurs.
+
+The depth of the jaw varies. It is slender in Pterodactylus, and is
+probably stronger relatively to the skull in Scaphognathus than in any
+other form. It fits between the teeth and bones of the alveolar border
+in the skull, in all the genera. In Dimorphodon its hinder border is
+partly covered by the descending edge of the malar process which these
+animals develop in common with some Dinosaurs, and some Anomodont
+reptiles, and many of the lower mammals. In this hinder region the lower
+jaw is sometimes perforated, in the same way as in Crocodiles. That
+condition is observed in Dimorphodon, but is not found in Pterodactylus.
+The lower jaw is always composite, being formed by several bones, as
+among reptiles and birds. The teeth are in the dentary bone or bones,
+and these bones are almost always blended as in most birds and Turtles,
+and not separate from each other as among Crocodiles, Lizards, and
+Serpents.
+
+An interesting contour for the lower border of the jaw is seen in
+Ornithostoma, as made known in figures of American examples by
+Professors Marsh and Williston. It deepens as it extends backwards for
+two-thirds its length, stops at an angle, and then the depth diminishes
+to the articulation with the skull. This angle of the lower jaw is a
+characteristic feature of the jaws of Mammals. It is seen in the
+monotreme Echidna, and is characteristic of some Theriodont Reptiles
+from South Africa, which in many ways resemble Mammals. The character
+is not seen in the jaws of specimens from the Oolitic rocks, but is
+developed in the toothed Ornithocheirus from the Cambridge Greensand,
+and is absent from the jaws of existing reptiles and birds.
+
+  [Illustration: FIG. 23  COMPARISON OF THE LOWER JAW IN ECHIDNA AND
+  ORNITHOSTOMA]
+
+
+SUMMARY OF CHARACTERS OF THE HEAD
+
+Taken as a whole, the head differs from other types of animals in a
+blending of characters which at the present day are found among Birds
+and Reptiles, with some structures which occur in extinct groups of
+animals with similar affinities, and perhaps a slight indication of
+features common to the lowest mammals. It is chiefly upon the head that
+the diverse views of earlier writers have been based. Cuvier was
+impressed with the reptilian aspect of the teeth; but in later times
+discoveries were made of Birds with teeth--Archaeopteryx, Ichthyornis,
+Hesperornis. The teeth are quite reptilian, being not unlike miniature
+teeth of Mosasaurus. If those birds had been found prior to the
+discovery of Pterodactyles, the teeth might have been regarded as a link
+with the more ancient birds, rather than a crucial difference between
+birds and reptiles.
+
+All the specimens show a lateral temporal hole in the bones behind the
+eye, and this is found in no bird or mammal, and is typical of such
+reptiles as Hatteria. The quadrate bone may not be so decisive as Cuvier
+thought it to be, for its form is not unlike the quadrate of a bird, and
+different, so far as I have seen, from that of living reptiles. This
+region of the head is reptilian, and if it occurred in a bird the
+character would be as astonishing as was the discovery of teeth in
+extinct birds. These characters of the head are also found in fossil
+animals named Dinosaurs, in association with many resemblances to birds
+in their bones.
+
+The palate might conceivably be derived from that of Hatteria by
+enlarging the small opening in the middle line in that reptile till it
+extended forward between the vomera; but it is more easily compared with
+a bird, which the animal resembles in its beak, and in the position of
+the nares. Excepting certain Lizards, all true existing Reptiles have
+the nostrils far forward and bordered by two premaxillary bones instead
+of one intermaxillary, as in Birds and Ornithosaurs. If nothing were
+known of the animal but its head bones, it would be placed between
+Reptiles and Birds.
+
+
+
+
+CHAPTER IX
+
+THE BACKBONE, OR VERTEBRAL COLUMN
+
+
+The backbone is a more deep-seated part of the skeleton than the head.
+It is more protected by its position, and has less varied functions to
+perform. Therefore it varies less in distinctive character within the
+limits of each of the classes of vertebrate animals than either the head
+or limbs. It is divided into neck bones, the cervical vertebrae; back
+bones, the dorsal vertebrae; loin bones, the lumbar vertebrae; the sacrum,
+or sacral vertebrae, which support the hind limbs; and the tail. Of these
+parts the tail is the least important, though it reaches a length in
+existing reptiles which sometimes exceeds the whole of the remainder of
+the body, and includes hundreds of vertebrae. It attains its maximum
+among serpents and lizards. In frogs it is practically absent. In some
+of the higher mammals it is a rudiment, which does not extend beyond the
+soft parts of the body.
+
+
+THE NECK
+
+The neck is more liable to vary than the back, with the habit of life of
+the animal. And although mammals almost always preserve the same number
+of seven bones in the neck, the bones vary in length between the short
+condition of the porpoise, in which the neck is almost lost, and the
+long bones which form the neck of the Llama, though even these may be
+exceeded by some fossil reptiles like Tanystrophoeus. In many mammals
+the neck bones do not differ in length or size from those of the back.
+In others, like the Horse and Ox, they are much broader and larger.
+
+There is the same sort of variation in the bones of the neck among
+birds, some being slender like the Heron, others broad like the Swan.
+But there is also a singular variation in number of vertebral bones in a
+bird's neck. At fewest there are nine, which equals the exceptionally
+large number found among mammals in the neck of one of the Sloths.
+Usually birds have ten to fifteen cervical vertebrae, and in the Swan
+there are twenty-three. Most of the neck bones of birds are relatively
+long, and the length of the neck is often greater than the remainder of
+the vertebral column.
+
+Reptiles usually have short necks. The common Turtle has eight bones in
+the neck, ten in the back. The two regions are sharply defined by the
+dorsal shield. Their articular ends are sometimes cupped in front, in
+the neck, sometimes cupped behind, or convex at both ends, or even
+flattened, or the articulation may be made exceptionally by the neural
+arch alone. Nine is the largest number of neck bones in existing
+Lizards, and there are usually nine in Crocodiles; so that reptiles
+closely approach mammals in number of the neck bones. It is remarkable
+that the maximum number in a mammal and in living reptiles should
+coincide with the minimum number in birds. Therefore the number of
+cervical vertebrae as an attribute of Mammal, Bird, or Reptile, can only
+be important from its constancy.
+
+German naturalists affirm on clear evidence that the Solenhofen
+Pterodactyles have seven cervical vertebrae. In many specimens there can
+be no doubt about the number, because the neck bones are easily
+distinguished from those of the back by their size; but the number is
+not always easy to count.
+
+As in Birds, the first vertebra, or atlas, in Pterodactyles is extremely
+short, and is generally--if not always--blended with the much longer
+second vertebra, named the axis. The front of the atlas forms a small
+rounded cup to articulate with the rounded ball of the basioccipital
+bone at the back of the skull. The third and fourth vertebrae are longer,
+but the length visibly shortens in the sixth and seventh.
+
+Sometimes the vertebrae are slender and devoid of strong spinous
+processes. This is the condition in the little _Pterodactylus
+longirostris_ and in the comparatively large _Cycnorhamphus Fraasii_, in
+which there is a slight median ridge along the upper surface of the arch
+of the vertebra. This condition is paralleled in birds with long necks,
+especially wading birds such as the Heron. Other Ornithosaurs, such as
+Ornithocheirus from the Cretaceous rocks, have the neck much more
+massive. The vertebrae are flattened on the under side. The arch above
+the nervous matter of the spinal cord has a more or less considerable
+transverse expansion, and may even be as wide as long. These vertebrae
+have proportions and form such as may be seen in Vultures or in the
+Swan. In either case the form of the neck bones is more or less
+bird-like, and the neural spine may be elevated, especially in
+Pterodactyles with long tails.
+
+One of the most distinctive features of the neck bones of a bird is the
+way in which the cervical ribs are blended with the vertebrae. They are
+small, and each is often prolonged in a needle-like rod at the side of
+the neck bone.
+
+In Ornithocheirus the cervical rib similarly blends with the vertebra by
+two articulations, as in mammals, so that it might escape notice but for
+the channel of a blood vessel which is thus inclosed. In several of the
+older Pterodactyles from Solenhofen the ribs of the neck vertebrae remain
+separated, as in a Crocodile, though still bird-like in their form,
+anterior position, and mode of attachment. In Terrapins and Tortoises
+the long neck vertebrae have no cervical ribs.
+
+  [Illustration: FIG. 24  UNITED ATLAS AND AXIS OF ORNITHOCHEIRUS
+  (Cambridge Greensand)]
+
+The articular surfaces between the bodies of the vertebrae, in the neck,
+are transversely oval. The middle part of this articular joint is made
+by the body of the vertebra; its outer parts are in the neural arch. In
+front this surface is a hollow channel, often more depressed than in any
+other animals. The corresponding surface behind is convex, with a
+process on each side at its lower outer angles (Fig. 25). It is a
+modification of the cup-and-ball form of vertebral articulation, which
+at the present day is eminently reptilian. Serpents and Crocodiles have
+the articulations similarly vertical, but in both the form of the
+articulation is a circle. In Lizards the articular cup is usually rather
+wider than deep, when the cup and ball are developed in the vertebrae; it
+differs from the vertical condition in pterodactyles in being oblique
+and much narrower from side to side. Only among Crocodiles and Hatteria
+is there a double articulation for the cervical rib, though in neither
+order have rib or vertebra in the neck the bird-like proportions which
+are usual in these animals. Pterodactyles show no resemblance to birds
+in this vertebral articulation. A Bird has the corresponding surface
+concave from side to side in front, but it is also convex from above
+downward, producing what is known as the saddle-shaped form which is
+peculiarly avian, being found in existing birds except in part of the
+back in Penguins. It is faintly approximated to in one or two neck
+vertebrae in man. Professor Williston remarks that in the toothless
+Pterodactyles of Kansas the hinder ball of the vertebral articulation is
+continued downward and outward as a concave articulation upon the
+processes at its outer corners. There are no mammals with a cup-and-ball
+articulation between the vertebrae, so that for what it is worth the
+character now described in Ornithosaurs is reptilian, when judged by
+comparison with existing animals.
+
+  [Illustration: FIG. 25.  CERVICAL VERTEBRA OF ORNITHOCHEIRUS
+  From the Cambridge Greensand]
+
+Low down on each side of the vertebra, at the junction of its body with
+the neural arch, is a large ovate foramen, transversely elongated, and
+often a little impressed at the border, which is the entrance of the
+air cell into the bone. These foramina are often one-third of the length
+of the neck vertebrae in specimens from the Cambridge Greensand, where
+the neck bones vary from three-quarters of an inch to about two and a
+half inches in length, and in extreme forms are as wide as long. The
+width of the interspace between the foramina is one-half the width of
+the vertebrae, though this character varies with different genera and
+species. Several species from the Solenhofen Slate have the neck long
+and slender, on the type of the Flamingo. In others the neck is thick
+and short--in the _Scaphognathus crassirostris_ and _Pterodactylus
+spectabilis_. Some genera with slender necks have the bones preserved
+with a curved contour, such as might suggest a neck carried like that of
+a Llama or a Camel. The neck is occasionally preserved in a curve like a
+capital #S#, as though about to be darted forward like that of a bird in
+the act of striking its prey. The genera of Pterodactyles with short
+necks may have had as great mobility of neck as is found among birds
+named Ducks and Divers; but those Pterodactyles with stout necks, such
+as Dimorphodon and Ornithocheirus, in which the vertebrae are large,
+appear to have been built more for strength than activity, and the neck
+bones have been chiefly concerned in the muscular effort to use the
+fighting power of the jaws in the best way.
+
+
+THE BACK
+
+The region of the back in a Pterodactyle is short as compared with the
+neck, and relatively is never longer than the corresponding region in a
+bird. The shortness results partly from the short length of the
+vertebrae, each of which is about as long as wide. There is also a
+moderate number of bones in the back. In most skeletons from Solenhofen
+these vertebrae between the neck and girdle of hip bones number from
+twelve to sixteen. They have a general resemblance in form to the dorsal
+vertebrae in birds. The greatest number of such vertebrae in birds is
+eleven. The number is small because some of the later vertebrae in birds
+are overlapped by the bones of the hip girdle, which extend forward and
+cover them at the sides, so that they become blended with the sacrum.
+This region of the skeleton in the Dimorphodon from the Lias is
+remarkable for the length of the median process, named the neural spine,
+which is prolonged upward like the spines of the early dorsal vertebrae
+of Horses, Deer, and other mammals. In this character they differ from
+living reptiles, and parallel some Dinosaurs from the Weald. The bones
+of the back in Ornithocheirus from the Cambridge Greensand show the
+under side to be well rounded, so that the articular surfaces between
+the vertebrae, though still rather wider than deep, are much less
+depressed than in the region of the neck. The neural canal for the
+spinal cord has become larger and higher, and the sides of the bone are
+somewhat compressed. Strong transverse processes for the support of the
+ribs are elevated above the level of the neural canal, at the sides of
+vertebrae compressed on the under sides, and directed outward. Between
+these lateral horizontal platforms is the compressed median neural
+spine, which varies in vertical height. The articulation of the ribs is
+not seen clearly. Isolated ribs from the Stonesfield Slate have
+double-headed dorsal ribs, like those of birds. In some specimens from
+the Solenhofen Slate like the Scaphognathus, in the University Museum at
+Bonn, dorsal ribs appear to be attached by a notch in the transverse
+process of the dorsal vertebra, which resembles the condition in
+Crocodiles. Variations in the mode of attachment of ribs among mammals
+may show that character to be of subordinate importance. Von Meyer has
+described the first pair of ribs as frequently larger than the others,
+and there appear in Rhamphorhynchus to be examples preserved of the
+sternal ribs, which connect the dorsal ribs with the sternum. Six pairs
+have been counted. A more interesting feature in the ribs consists in
+the presence behind the sternum, which is shorter than the corresponding
+bone in most birds, of median sternal ribs. They are slender #V#-shaped
+bones in the middle line of the abdomen, which overlapped the ends of
+the dorsal ribs like the similar sternal bones of reptiles. Such
+structures are unknown among Birds and Mammals. There is no trace in the
+dorsal ribs of the claw-like process, which extends laterally from rib
+to rib as a marked feature in many birds. Its presence or absence may
+not be important, because it is represented by fibro-cartilage in the
+ribs of crocodiles, and may be a small cartilage near the head of the
+rib in serpents, and is only ossified in some ribs of the New Zealand
+reptile Hatteria. So that it might have been present in a fossil animal
+without being ossified and preserved. Although the structure is
+associated with birds, it is possibly also represented by the great bony
+plates which cover the ribs in Chelonians, and combine to form the
+shield which covers the turtle's back. The structure is as
+characteristic of reptiles as of birds, but is not necessarily
+associated with either.
+
+  [Illustration: FIG. 26
+
+  The upper figures show the side and back of a dorsal vertebra of
+  Ornithocheirus compared with corresponding views of the side and
+  back of a dorsal vertebra of a Crocodile]
+
+There are two remarkable modifications of the early dorsal vertebrae in
+some of the Cretaceous Pterodactyles. First, in the genus Ornithodesmus
+from the Weald the early dorsal vertebrae are blended together into a
+continuous mass, like that which is found in the corresponding region of
+the living Frigate-bird, only more consolidated, and similar to that
+consolidated structure found behind the dorsal vertebrae, known as the
+sacrum, made by the blending of the vertebrae into a solid mass which
+supports the hip bones. Secondly, in some of the Cretaceous genera of
+Pterodactyles of Europe and America the vertebrae in the front part of
+the back are similarly blended, but their union is less complete; and in
+genera Ornithocheirus and Ornithostoma--the former chiefly English, the
+latter chiefly American--the sides of the neural spines are flattened to
+form an oval articular surface on each side, which gives attachment to
+the flattened ends of their shoulder-blade bones named the scapulae. This
+condition is found in no other animals. Three vertebrae appear to have
+their neural arches thus united together. The structure so formed may be
+named the notarium to distinguish it from the sacrum.
+
+
+SACRUM
+
+For some mysterious reason the part of the backbone which lies between
+the bones of the hips and supports them is termed the sacrum. Among
+living reptiles the number of vertebrae in this region is usually two, as
+in lizards and crocodiles. There are other groups of fossil reptiles in
+which the number of sacral vertebrae is in some cases less and in other
+cases more. There is, perhaps, no group in which the sacrum makes a
+nearer approach to that of birds than is found among these
+Pterodactyles, although there are more sacral vertebrae in some
+Dinosaurs. In birds the sacral vertebrae number from five to twenty-two.
+In bats the number is from five to six. In some Solenhofen species, such
+as _Pterodactylus dubius_ and _P. Kochi_ and _P. grandipelvis_, the
+number is usually five or six. The vertebrae are completely blended. The
+pneumatic foramina in the sacrum, so far as they have been observed, are
+on the under sides of the transverse processes; while in the
+corresponding notarial structure in the shoulder girdle the foramina are
+in front of the transverse processes. Almost any placental mammal in
+which the vertebrae of the sacral region are anchylosed together has a
+similar sacrum, which differs from that of birds in the more complete
+individuality of the constituent bones remaining evident. The transverse
+processes in front of the sacrum are wider than in its hinder part; so
+that the pelvic bones which are attached to it converge as they extend
+backward, as among mammals. The bodies of the vertebrae forming the
+sacrum are similar in length to those of the back. Each transverse
+process is given off opposite the body of its own vertebra, but from a
+lower lateral position than in the region of the back, in which the
+vertebrae are free.
+
+  [Illustration: FIG. 27.  SACRUM OF RHAMPHORHYNCHUS
+
+  Showing the complete blending of the vertebrae and ribs as in a bird,
+  with the well-defined Iliac bones, produced chiefly in front of the
+  acetabulum for the head of the femur.]
+
+The hip bones are closely united with the sacrum by bony union, and
+rarely appear to come away from the sacral vertebrae, as among mammals
+and reptiles, though this happens with the Lias Pterodactyles. In the
+Stonesfield Slate and Solenhofen Slate the slender transverse processes
+from the vertebrae blend with the ilium of the hip girdle, and form a
+series of transverse foramina on each side of the bodies of the
+vertebrae. In the Cambridge Greensand genera the part of the ilium above
+the acetabulum for the articular head of the femur appears to be always
+broken away, so that the relation of the sacrum to the pelvis has not
+been observed. This character is no mark of affinity, but only shows
+that ossification obliterated sutures among these animals in the same
+way as among birds.
+
+The great difference between the sacrum of a Pterodactyle and that of a
+bird has been rendered intelligible by the excellent discussion of the
+sacral region in birds made by Professor Huxley. He showed that it is
+only the middle part of the sacrum of a chicken which corresponds to the
+true sacrum of a reptile, and comprises the five shortest of the
+vertebrae; while the four in front correspond to those of the lower part
+of the back, which either bear no ribs or very short ribs, and are known
+as the lumbar region in mammals, so that the lower part of the back
+becomes blended with the sacrum, and thus reduces the number of dorsal
+vertebrae. Similarly the five vertebrae which follow the true sacral
+vertebrae are originally part of the tail, and have been blended with the
+other vertebrae in front, in consequence of the extension along them of
+the bird's hip bones. This interpretation helps to account for the great
+length of the sacrum in many birds, and also explains in part the
+singular shortness of the tail in existing birds. The Ornithosaur sacrum
+has neither the lumbar nor the caudal portions of the sacrum of a bird.
+
+
+
+THE TAIL
+
+The tail is perhaps the least important part of the skeleton, since it
+varies in character and length in different genera. The short tails seen
+in typical pterodactyles include as few as ten vertebrae in
+_Pterodactylus grandipelvis_ and _P. Kochi_, and as many as fifteen
+vertebrae in _Pterodactylus longirostris_. The tails are more like those
+of mammals than existing birds, in which there are usually from six to
+ten vertebrae terminating in the ploughshare bone. But just as some
+fossil birds, like the Archaeopteryx, have about twenty long and slender
+vertebrae in the tail, so in the pterodactyle Rhamphorhynchus this region
+becomes greatly extended, and includes from thirty-eight to forty
+vertebrae. In Dimorphodon the tail vertebrae are slightly fewer. The
+earliest are very short, and then they become elongated to two or three
+times the length of the early tail vertebrae, and finally shorten again
+towards the extremity of the tail, where the bones are very slender. In
+all long-tailed Ornithosaurians the vertebrae are supported and bordered
+by slender ossified ligaments, which extend like threads down the tail,
+just as they do in Rats and many other mammals and in some lizards.
+
+Professor Marsh was able to show that the extremity of the tail in
+Rhamphorhynchus sometimes expands into a strong terminal caudal membrane
+of four-sided somewhat rhomboidal shape. He regards this membrane as
+having been placed vertically. It is supported by delicate processes
+which represent the neural spines of the vertebrae prolonged upward. They
+are about fifteen in number. A corresponding series of spines on the
+lower border, termed chevron bones, equally long, were given off from
+the junctions of the vertebrae on their under sides, and produced
+downward. This vertical appendage is of some interest because its
+expansion is like the tail of a fish. It suggests the possibility of
+having been used in a similar way to the caudal fin as an organ for
+locomotion in water, though it is possible that it may have also formed
+an organ used in flight for steering in the air.
+
+  [Illustration: FIG. 28.  EXTREMITY OF THE TAIL OF _RHAMPHORHYNCHUS
+  PHYLLURUS_ (MARSH)
+
+  Showing the processes on the upper and under sides of the vertebrae
+  which make the terminal leaf-like expansion]
+
+The tail vertebrae from the Cambridge Greensand are mostly found isolated
+or with not more than four joints in association. They are very like the
+slender type of neck vertebrae seen in long-necked pterodactyles, but are
+depressed, and though somewhat wider are not unlike the tail vertebrae of
+the Rhamphorhynchus. The pneumatic foramen in them is a mere puncture.
+They have no transverse processes or neural spines, nor indications of
+ribs, or chevron bones.
+
+The hindermost specimens of tail vertebrae observed have the neural arch
+preserved to the end, as among reptiles; whereas in mammals this arch
+becomes lost towards the end of the tail. The processes by which the
+vertebrae are yoked together are small. There is nothing to suggest that
+the tail was long, except the circumstance that the slender caudal
+vertebrae are almost as long as the stout cervical vertebrae in the same
+animal. No small caudal vertebrae have ever been found in the Cambridge
+Greensand. The tail is very short, according to Professor Williston, in
+the toothless Ornithostoma in the Chalk of Kansas.
+
+
+
+
+CHAPTER X
+
+THE HIP-GIRDLE AND HIND LIMB
+
+
+The bones of the hip-girdle form a basin which incloses and protects the
+abdominal vital organs. It consists on each side of a composite bone,
+the unnamed bones--_ossa innominata_ of the older anatomists--which are
+each attached to the sacrum on their inner side, and on the outer side
+give attachment to the hind limbs. As a rule three bones enter into the
+borders of this cup, termed the acetabulum, in which the head of the
+thigh bone, named the Femur, moves with a more or less rotary motion.
+
+There are a few exceptions in this division of the cup between three
+bones, chiefly among Salamanders and certain Frogs. In Crocodiles the
+bone below the acetabular cup is not divided into two parts. And in
+certain Plesiosaurs from the Oxford Clay--Muraenosaurus--the actual
+articulation appears to be made by two bones--the ilium and ischium. The
+three bones which form each side of the pelvis are known as the ilium,
+or hip bone, sometimes termed the aitch bone; secondly, the ischium, or
+sitz bone, being the bone by which the body is supported in a sitting
+position; and thirdly the pubis, which is the bone in front of the
+acetabulum. The pubic bones meet in the middle line of the body on the
+under side of the pelvis in man, and on each side are partly separated
+from the ischia by a foramen, spoken of as the obturator foramen, which
+in Pterodactyles is minute and almost invisible, when it exists.
+
+There is often a fourth bony element in the pelvis. In some Salamanders
+a single cartilage is directed forward, and forked in front. According
+to Professor Huxley something of this kind is seen in the Dog. The pair
+of bones which extend forward in front of the pelvis in Crocodiles may
+be of the same kind, in which case they should be called prepubic bones.
+But among the lower mammals named marsupials a pouch is developed for
+the protection of the young and supported by two slender bones attached
+to the pubes, and these bones have long been known as marsupial bones.
+In a still lower group of mammalia named monotremata, which lay eggs,
+and in many ways approximate to reptiles and birds, stronger bones are
+developed on the front edge of the pubes, and termed prepubic bones.
+They do not support a marsupium.
+
+Naturalists have been uncertain as to the number of bones in the pelvis
+of Pterodactyles, because the bones blend together early in life, as in
+birds. Some follow the Amphibian nomenclature, and unite the ischium and
+pubis into one bone, which is then termed ischium, when the prepubis is
+termed the pubis, and regarded as removed from the acetabulum. There is
+no ground for this interpretation, for the sutures are clear between the
+three pelvic bones in the acetabulum in some specimens, like
+_Cycnorhamphus Fraasii_, from Solenhofen, and some examples of
+Ornithocheirus from the Cambridge Greensand. Pterodactyles all have
+prepubic bones, which are only known in Ornithorhynchus and Echidna
+among mammals, and are absent from the higher mammals and birds. They
+are unknown in any other existing animals, unless present in Crocodiles,
+in which ischium and pubis are always undivided. Therefore it is
+interesting to examine the characters of the Ornithosaurian pelvis.
+
+The acetabulum for the head of the femur is imperforate, being a simple
+oval basin, as in Chelonian reptiles and the higher Mammals. It never
+shows the mark of the ligamentous attachment to the head of the femur,
+which is seen in Mammals. In Birds the acetabulum is perforated, as in
+many of the fossils named Dinosaurs, and in Monotremata.
+
+  [Illustration: FIG. 29.  COMPARISON OF THE LEFT SIDE OF THE PELVIS IN
+  A BIRD AND A PTERODACTYLE]
+
+Secondly, the ilium is elongated, and extends quite as much in front of
+the acetabulum as behind it. The bone is not very deep in this front
+process. Among existing animals this relation of the bone is nearer to
+birds than to any other type, since birds alone have the ilium extended
+from the acetabulum in both directions. The form of the Pterodactyle
+ilium is usually that of the embryo bird, and its slender processes
+compare in relative length better with those of the unhatched fowl and
+Apteryx of New Zealand than with the plate-like form in adult birds.
+
+In mammals the ilium is directed forward, and even in the Cape ant-eater
+Orycteropus there is only an inappreciable production of the bone
+backward behind the acetabulum. Among reptiles the general position of
+the acetabulum is at the forward termination of the ilium, though the
+Crocodile has some extension of the bone in both directions, without
+forming distinct anterior and posterior processes. This anterior and
+posterior extension of the ilium is seen in the Theriodont reptiles of
+Russia and of South Africa, as well as in Dinosaurs.
+
+  [Illustration: FIG. 30.  LEFT PELVIC BONES WITH PREPUBIC BONE IN
+  _PTERODACTYLUS LONGIROSTRIS_]
+
+Thirdly, in all pterodactyles the ischium and pubis are more or less
+completely blended into a sheet of bone, unbroken by perforation, though
+there is usually a minute vascular foramen; or the lower border may be
+notched between the ischium and the pubis, as in some of the Solenhofen
+species, and the pubis does not reach the median line of the body. But
+in Dimorphodon the pelvic sheet of bone is unbroken by any notch or
+perforation. The notch between the ischium and pubis is well marked in
+_Pterodactylus longirostris_, and better marked in _Pterodactylus
+dubius_, _Cycnorhamphus Fraasii_, and Rhamphorhynchus. The fossil
+animals which appear to come nearest to the Pterodactyles in the
+structure of the pelvis are Theriodonts from the Permian rocks of
+Russia. The type known as Rhopalodon has the ilium less prolonged front
+and back, and is much deeper than in any Pterodactyle; but the
+acetabulum is imperforate, and the ischium and pubis are not always
+completely separated from each other by suture. In the pelvis referred
+to the Theriodont Deuterosaurus there is some approximation to the
+pelvis of Rhamphorhynchus and of _Pterodactylus dubius_ in the depth of
+the division between the pubis and ischium.
+
+  [Illustration: FIG. 31  PELVIS AND PREPUBIC BONES OF RHAMPHORHYNCHUS
+
+  On the left-hand side the two prepubic bones are separate. On the
+  right-hand they are united into a transverse bar which overlaps the
+  front of pelvis seen from the under side]
+
+There are three modifications of the Ornithosaurian pelvis. First, the
+type of Rhamphorhynchus, in which the pubis and ischium are inclined
+somewhat backward, and in which the two prepubic bones are triangular,
+and are often united together to form a transverse bow in front of the
+pubic region.
+
+Secondly, there is the ordinary form of pelvis in which the pubis and
+ischium usually unite with each other down their length, as in
+Dimorphodon, but sometimes, as in _Pterodactylus dubius_, divide
+immediately below the acetabulum. All these types possess the
+paddle-shaped prepubic bones, which are never united in the median line.
+
+Thirdly, there is the cretaceous form indicated by Ornithocheirus and
+Ornithostoma, in which the posterior half of the ilium is modified in a
+singular way, since it is more elevated towards the sacrum than the
+anterior half, suggesting the contour of the upper border of the ilium
+in a lizard. Without being reptilian--the anterior prolongation of the
+bone makes that impossible--it suggests the lizards. This type also
+possesses prepubic bones. They appear, according to Professor Williston,
+to be more like the paddle-shaped bones of Pterodactylus than like the
+angular bones in Rhamphorhynchus. The prepubic bones are united in the
+median line as in Rhamphorhynchus. But their median union in that genus
+favours the conclusion that the bones were united in the median line in
+all species, though they are only co-ossified in these two families.
+
+  [Illustration: FIG. 32.  THE PELVIC BONES OF AN ALLIGATOR SEEN FROM
+  BELOW
+
+  The bones in front are here regarded as prepubic, but are commonly
+  named pubic]
+
+This median union of the prepubic bones is a difference from those
+mammals like the Ornithorhynchus and Echidna, which approach nearest to
+the Reptilia. In them the prepubic bones have a long attachment to the
+front margin of the pubis, and extend their points forward without any
+tendency for the anterior extremities to approximate or unite. The
+marsupial mammals have the same character, keeping the marsupial bones
+completely distinct from each other at their free extremities. The only
+existing animals in which an approximation is found to the prepubic
+bones in Pterodactyles are Crocodiles, in bones which most writers term
+the pubic bones. This resemblance, without showing any strong affinity
+with the Crocodilia, indicates that Crocodiles have more in common with
+the fossil flying animals than any other group of existing reptiles; for
+other reptiles all want prepubic bones, or bones in front of the pubic
+region.
+
+
+THE HIND LIMB
+
+The hind limb is exceptionally long in proportion to the back. This is
+conspicuous in the skeletons of the short-tailed Pterodactyles, and is
+also seen in Dimorphodon. In Rhamphorhynchus the hind limb is relatively
+much shorter, so that the animal, when on all fours, may have had an
+appearance not unlike a Bat in similar position. The limb is
+exceptionally short in the little _Ptenodracon brevirostris_. The bones
+of the hind limb are exceptionally interesting. One remarkable feature
+common to all the specimens is the great elongation of the shin bones
+relatively to the thigh bones. The femur is sometimes little more than
+half the length of the tibia, and always shorter than that bone. The
+proportions are those of mammals and birds. Some mammals have the leg
+shorter than the thigh, but mammals and birds alone, among existing
+animals, have the proportions which characterise Pterodactyles. The
+foot appears to have been applied to the ground not always as in a bird,
+but more often in the manner of reptiles, or mammals in which the digits
+terminate in claws.
+
+
+THE FEMUR
+
+  [Illustration: FIG. 33.  THE FEMUR
+
+  On the right is a front view of femur of a bear. In the middle are
+  front and side views of the femur of Ornithocheirus. On the left is
+  the femur of Echidna. These comparisons illustrate the mammalian
+  characters of the Pterodactyle thigh bone]
+
+The thigh bone, on account of the small size of many of the specimens,
+is not always quite clear evidence as an indication of technical
+resemblance to other animals. The bone is always a little curved, has
+always a rounded, articular head, and rounded distal condyles. Its most
+remarkable features are shown in the large, well-preserved specimens
+from the Cambridge Greensand. The rounded, articular head is associated
+with a constricted neck to the bone, followed by a comparatively
+straight shaft with distal condyles, less thickened than in mammals. No
+bird is known, much less any reptile, with a femur like Ornithocheirus.
+Only among Mammals is a similar bone known with a distinct neck; and
+only a few mammals have the exceptional characters of the rounded head
+and constricted neck at all similar to the Cretaceous Pterodactyles. A
+few types, such as the higher apes, the Hyrax, and animals especially
+active in the hind limb, have a femur at all resembling the Pterodactyle
+in the pit for the obturator externus muscle, behind the trochanter
+major, such as is seen in a small femur from Ashwell. The femur varies
+in different genera, so as to suggest a number of mammalia rather than
+any particular animal for comparison. These approximations may be
+consequences of the ways in which the bones are used. When functional
+modifications of the skeleton are developed, so as to produce similar
+forms of bones, the muscles to which they give attachment, which act
+upon the bones, and determine their growth, are substantially the same.
+In the _Pterodactylus longirostris_ the femur corresponds in length to
+about eleven dorsal vertebrae. The end next the shin bone is less
+expanded than is usual among Mammals, and rather suggests an approach to
+the condition in Crocodiles, in the moderate thickness and breadth of
+the articular end, and the slight development of the terminal
+pulley-joint. One striking feature of the femur is the circumstance that
+the articular head, as compared with the distal end, is directed forward
+and very slightly inward and upward. So that allowing for the outward
+divergence of the pelvic bones, as they extend forward, there must have
+been a tendency to a knock-kneed approximation of the lower ends of the
+thigh bones, as in Mammals and Birds, rather than the outward divergence
+seen in Reptiles.
+
+Apparently the swing of the leg and foot, as it hung on the distal end
+of the femur, must have tended rather to an inward than to an outward
+direction, so that the feet might be put down upon the same straight
+line; this arrangement suggests rapid movement.
+
+  [Illustration: FIG. 34.  COMPARISON OF THE TIBIA AND FIBULA IN
+  ORNITHOSAUR AND VULTURE]
+
+
+TIBIA AND FIBULA
+
+In _Pterodactylus longirostris_ the tibia is slender, more than a fifth
+longer than the femur. A crest is never developed at the proximal end,
+like that seen in the Guillemot and Diver and other water birds. The
+bone is of comparatively uniform thickness down the shaft in most of the
+Solenhofen specimens, as in most birds. At the distal end the shin bone
+commonly has a rounded, articular termination, like that seen in birds.
+This is conspicuous in the _Pterodactylus grandis_. In other specimens
+the tarsal bones, which form this pulley, remain distinct from the
+tibia; and the upper row of these bones appears to consist of two
+bones, like those which in many Dinosaurs combine to form the
+pulley-like end of the tibia which represents the bird's drum-stick
+bone. They correspond with the ankle bones in man named astragalus and
+os calcis.
+
+Complete English specimens of tibia and fibula are found in the genus
+Dimorphodon from the Lias, in which the terminal pulley of the distal
+end has some expansion, and is placed forward towards the front of the
+tibia, as in some birds. The rounded surface of the pulley is rather
+better marked than in birds. The proximal end of the shaft is relatively
+stout, and is modified by the well-developed fibula, which is a short
+external splint bone limited to the upper half of the tibia, as in
+birds; but contributing with it to form the articular surface for the
+support of the lower end of the femur, taking a larger share in that
+work than in birds. Frequently there is no trace of the fibula visible
+in Solenhofen specimens as preserved; or it is extremely slender and
+bird-like, as in _Pterodactylus longirostris_. In Rhamphorhynchus it
+appears to extend the entire length of the tibia, as in Dinosaurs. In
+the specimens from the Cambridge Greensand there is indication of a
+small proximal crest to the tibia with a slight ridge, but no evidence
+that this is due to a separate ossification. The patella, or knee-cap,
+is not recognised in any fossil of the group. There is no indication of
+a fibula in the specimens thus far known from the Chalk rocks either of
+Kansas in America, or in England.
+
+The region of the tarsus varies from the circumstance that in many
+specimens the tibia terminates downward in a rounded pulley, like the
+drum-stick of a bird; while in other specimens this union of the
+proximal row of the tarsal bones with the tibia does not take place, and
+then there are two rows of separate tarsal bones, usually with two bones
+in each row. When the upper row is united with the tibia the lower row
+remains distinct from the metatarsus, though no one has examined these
+separate tarsal bones so as to define them.
+
+
+THE FOOT
+
+  [Illustration: FIG. 35.  METATARSUS AND DIGITS IN THREE TYPES OF
+  ORNITHOSAURS]
+
+The foot sometimes has four toes, and sometimes five. There are four
+somewhat elongated, slender metatarsal bones, which are separate from
+each other and never blended together, as in birds. There has been a
+suspicion that the metatarsal bones were separate in the young
+Archaeopteryx. In the young of many birds the row of tarsal bones at the
+proximal end of the metatarsus comes away, and there is a partial
+division between the metatarsal bones, though they remain united in the
+middle. And among Penguins, in which the foot bones are applied to the
+ground instead of being carried in the erect position of ordinary birds,
+there is always a partial separation between the metatarsal bones,
+though they become blended together. The Pterodactyle is therefore
+different from birds in preserving the bones distinct through life, and
+this character is more like Reptiles than Mammals. The individual bones
+are not like those of Dinosaurs, and diverge in Rhamphorhynchus as
+though the animals were web-footed. There is commonly a rudimentary
+fifth metatarsal. It is sometimes only a claw-shaped appendage, like
+that seen in the Crocodile. It is sometimes a short bone, completely
+formed, and carrying two phalanges in Solenhofen specimens: though no
+trace of these phalanges is seen in the large toothless Pterodactyles
+from the Cretaceous rocks of North America. In the _Pterodactylus
+longirostris_ the number of foot bones on the ordinary digits is two,
+three, four, five, as in lizards; but the short fifth metatarsal has
+only two toe bones. In Dimorphodon the fifth digit was bent upward, and
+supported a membrane for flight. There are slight variations in the
+number of foot bones. In the species _Pterodactylus scolopaciceps_ the
+number of bones in the toes follows the formula two, three, three, four.
+In _Pterodactylus micronyx_ the number is two, three, three, three. The
+terminal claws are much less developed than is usual with Birds; and
+there is a difference from Bats in the unequal length of the digits.
+Taken as a whole, the foot is perhaps more reptilian than avian, and in
+some genera is crocodilian.
+
+The foot is the light foot of an active animal. Von Meyer thought that
+the hind legs were too slender to enable the animal to walk on land; and
+Professor Williston, of the University of Kansas, remarks that the
+rudimentary claws and weak toes indicate that the animal could not have
+used the feet effectively for grasping, while the exceedingly free
+movement of the femur indicates great freedom of movement of the hind
+legs; and he concludes that the function of the legs was chiefly for
+guidance in flight through their control over the movements, and
+expresses his belief that the animal could not have stood upon the
+ground with its feet. There may be evidence to sustain other views. If
+the limb bones are reconstructed, they form limbs not wanting in
+elegance or length. If it is true, as Professor Williston suggests, that
+the weight of his largest animals with the head three feet long, and a
+stretch of wing of eighteen or nineteen feet, did not exceed twenty
+pounds, there can be no objection to regarding these animals as
+quadrupeds, or even as bipeds, on the ground of the limbs lacking the
+strength necessary to support the body. The slender toes of many birds,
+and even the two toes of the ostrich, may be thought to give less
+adequate support for those animals than the metatarsals and digits of
+Pterodactyles.
+
+
+
+
+CHAPTER XI
+
+SHOULDER-GIRDLE AND FORE LIMB
+
+
+STERNUM
+
+The sternum is always a distinguishing part of the bony structure of the
+breast. In Crocodiles it is a cartilage to which the sternal ribs unite;
+and upon its front portion a flat knife-like bone called the
+interclavicle is placed. In lizards like the Chameleon, it is a
+lozenge-shaped structure of thin bony texture, also bearing a long
+interclavicle, which supports the clavicular bones, named collar bones
+in man, which extend outward to the shoulder blades. Among mammals the
+sternum is usually narrow and flat, and often consists of many
+successive pieces in the middle line, on the under side of the body.
+Among Bats the anterior part is somewhat widened from side to side, to
+give attachment to the collar bones, but the sternum still remains a
+narrow bone, much narrower than in Dolphins, and not differing in
+character from many other Mammals, notwithstanding the Bat's power of
+flight. The bone develops a median keel for the attachment of the
+muscles of the breast, but something similar is seen in burrowing
+Insectivorous mammals like the Moles. So that, as Von Meyer remarked,
+the presence of a keel on the sternum is not in itself sufficient
+evidence to prove flight.
+
+Among birds the sternum is greatly developed. Broad and short in the
+Ostrich tribe, it is devoid of a keel; and therefore the keel, if
+present in a bird, is suggestive of flight. The keel is differently
+developed according to the mode of attachment of the several pectoral
+muscles which cover a bird's breast. In several water birds the keel is
+strongly developed in front, and dies away towards the hinder part of
+the sternum, as in the Cormorant and its allies. The sternum in German
+Pterodactyles is most nearly comparable to these birds.
+
+  [Illustration: FIG. 36.  COMPARISON OF THE STERNUM]
+
+In the Solenhofen Slate the sternum is fairly well preserved in many
+Ornithosaurs. It is relatively shorter than in birds, and is broader
+than long; but not very like the sternum of reptile or mammal in form.
+The keel is limited to the anterior part of the shield of the sternum,
+as in Merganser and the Cormorant, and is prolonged forward for some
+distance in advance of it. Von Meyer noticed the resemblance of this
+anterior process to the interclavicle of the Crocodile in position; but
+it is more like the keel of a bird's sternum, and is not a separate bone
+as in Reptiles. In Pterodactyles from the Cretaceous rocks, the side
+bones, called coracoids, are articulated to saddle-shaped surfaces at
+the hinder part of the base of this keel, which are parallel in
+Ornithocheirus, as in most birds, but overlap in Ornithodesmus, as in
+Herons and wading birds.
+
+  [Illustration: FIG. 37.  STERNUM IN ORNITHOCHEIRUS FROM THE CAMBRIDGE
+  GREENSAND
+
+  Showing the strong keel and the facets for the coracoid bones on its
+  hinder border above the lateral constrictions]
+
+The keel was pneumatic, and when broken is seen to be hollow, and
+appears to have been exceptionally high in Rhamphorhynchus, a genus in
+which the wing bones are greatly elongated. Von Meyer found in
+Rhamphorhynchus on each side of the sternum a separate lateral plate
+with six pairs of sternal ribs, which unite the sternum with the dorsal
+ribs, as in the young of some birds. The hinder surface of the sternum
+is imperfectly preserved in the toothless Pterodactyles of Kansas.
+Professor Williston states that the bone is extremely thin and
+pentagonal in outline, projecting in front of the coracoids, in a stout,
+blunt, keel-like process, similar to that seen in the Pterodactyles of
+the Cambridge Greensand. American specimens have not the same notch
+behind the articulation for the coracoid to separate it from the
+transverse lateral expansion of the sternal shield. The lateral margin
+in the Cambridge Greensand specimens figured by Professor Owen and
+myself is broken; but Professor Williston had the good fortune to find
+on the margin of the sternum the articular surfaces which gave
+attachment to the sternal ribs. The margin of the sternal bone thickens
+at these facets, four of which are preserved. The sternum in
+Ornithostoma was about four and a half inches long by less than five and
+a half inches wide. The median keel extends forward for rather less than
+two inches, while in the smaller Cambridge species of Ornithocheirus it
+extends forward for less than an inch and a half.
+
+A sternum of this kind is unlike that of any other animal, but has most
+in common with a bird; and may be regarded as indicating considerable
+power of flight. The bone cannot be entirely attributed to the effect of
+flight, since there is no such expanded sternal shield in Bats. The
+small number of sternal ribs is even more characteristic of birds than
+mammals or reptiles.
+
+
+THE SHOULDER-GIRDLE
+
+The bones which support the fore limb are one of the distinctive regions
+of the skeleton defining the animal's place in nature. Among most of the
+lower vertebrata, such as Amphibians and Reptiles, the girdle is a
+double arch--the arch of the collar bone or clavicles in front, and the
+arch of the shoulder-blade or scapula behind. The clavicular arch, when
+it exists, is formed of three or five parts--a medium bar named the
+interclavicle, external to which is a pair of bones called clavicles,
+reaching to the front of the scapulae when they are present; and
+occasionally there is a second pair of bones called supraclavicles,
+extending from the clavicles up the front margins of the scapulae. Thus
+the clavicular arch is placed in front of the scapular arch. The
+supraclavicles are absent from all living Reptiles, and the clavicles
+are absent from Crocodiles. The interclavicle is absent from all mammals
+except Echidna and Ornithorhynchus. Clavicles also may be absent in some
+orders of mammals. Hence the clavicular arch may be lost, though the
+collar bones are retained in man.
+
+The scapular arch also is more complicated and more important in the
+lower than in the higher vertebrata. It may include three bones on each
+side named coracoid, precoracoid, and scapula. But in most vertebrates
+the coracoid and precoracoid appear never to have been segmented so as
+to be separated from each other; and it is only among extinct types of
+reptiles, which appear to approximate to the Monotreme mammals, that
+separate precoracoid bones are found; though among most mammals,
+probably, there are stages of early development in which precoracoids
+are represented by small cartilages, though few mammals except Edentata
+like the Sloths and Ant-eaters, retain even the coracoids as distinct
+bones. Therefore, excepting the Edentata and the Monotremes, the
+distinctive feature of the mammalian shoulder-girdle appears to be that
+the limbs are supported by the shoulder-blades, termed the scapulae.
+
+Among reptiles there are several distinct types of shoulder-girdle.
+Chelonians possess a pair of bones termed coracoids which have no
+connexion with a sternum; and their scapulae are formed of two widely
+divergent bars, divided by a deeper notch than is found in any fossil
+reptiles. Among Lizards both scapula and coracoid are widely expanded,
+and the coracoid is always attached to the sternum. Chameleons have the
+blade of the scapula long and slender, but the coracoid is always as
+broad as it is long. Crocodiles have the bone more elongated, so that it
+has somewhat the aspect of a very strong first sternal rib when seen on
+the ventral face of the animal. The bone is perforated by a foramen,
+which would probably lie in the line of separation from the precoracoid
+if any such separation had ever taken place. The scapula, or
+shoulder-blade, of Crocodiles is a similar flat bone, very much shorter
+than the scapula of a Chameleon, and more like that of the New Zealand
+Hatteria. Thus there is very little in common between the several
+reptilian types of shoulder-girdle.
+
+  [Illustration: FIG. 38.  COMPARISON OF SCAPULA AND CORACOID IN THREE
+  PTERODACTYLES AND A BIRD]
+
+In birds the apparatus for the support of the wings has a far-off
+resemblance to the Crocodilian type. The coracoid bones, instead of
+being directed laterally outward and upward from the sternum, as among
+Crocodiles, are directed forward, so as to prolong the line of the
+breast bone, named the sternum. The bird's coracoid is sometimes
+flattened towards the breast bone among Swans and other birds; yet as a
+rule the coracoid is a slender bar, which combines with the still more
+slender and delicate blade of the scapula, which rests on the ribs, to
+make the articulation for the upper arm bone. Among reptiles the scapula
+and coracoid are more or less in the same straight line, as in the
+Ostrich, but in birds of flight they meet at an angle which is less than
+a right angle, and where they come in contact the external surface is
+thickened and excavated to make the articulation for the head of the
+humerus. There is nothing like this shoulder-girdle outside the class of
+birds, until it is compared with the corresponding structure in these
+extinct animals called Pterodactyles. The resemblance between the two is
+surprising. It is not merely the identity of form in the coracoid bone
+and the scapula, but the similar angle at which they meet and the
+similar position of the articulation for the humerus. Everything in the
+Pterodactyle's shoulder-girdle is bird-like, except the absence of the
+representative of the clavicles, that forked #V#-shaped bone of the bird
+which in scientific language is known as the furculum, and is popularly
+termed the "merry-thought." This kind of shoulder-girdle is found in the
+genera from the Lias and the Oolitic rocks, both of this country and
+Germany.
+
+In the Cretaceous rocks the scapula presents, in most cases, a different
+appearance. The coracoid is an elongated, somewhat triangular bone,
+compressed on the outer margin as in birds, but differing alike from
+birds and other Pterodactyles in not being prolonged forward beyond the
+articulation for the humerus. In these Cretaceous genera, toothed and
+toothless alike, the articulation for the upper arm bone truncates the
+extremity of the coracoid, so that the bone is less like that of a bird
+in this feature. Perhaps it shows a modification towards the crocodilian
+direction. The scapula, which unites with the coracoid at about a right
+angle, is similarly truncated by the articular surface for the humerus;
+but the bone is somewhat expanded immediately beyond the articulation,
+and compressed; and instead of being directed backward, it is directed
+inward over the ribs to articulate with the neural arches of the early
+dorsal vertebrae in the genera found in strata associated with the Chalk.
+As the bone approaches this articulation, it thickens and widens a
+little, becoming suddenly truncated by an ovate facet, which exactly
+corresponds to the transversely ovate impression, concave from front to
+back, which is seen in the neural arches of the dorsal vertebrae on which
+it fits. This condition is not present in all Cretaceous Pterodactyles.
+It does not occur in the Kansas fossil, named by Professor Marsh,
+Nyctodactylus. And it appears to be absent from the Pterodactyles of the
+English Weald, named Ornithodesmus.
+
+  [Illustration: FIG. 39.  THE NOTARIUM
+
+  An ossification which gives attachment to the scapulae seen in the
+  early dorsal vertebra of Ornithocheirus
+
+  (From the Cambridge Greensand)]
+
+  [Illustration: FIG. 40.  RESTORATION OF THE SHOULDER-GIRDLE IN THE
+  CRETACEOUS ORNITHOCHEIRUS
+
+  Showing how the scapulae articulate with a vertebra and the
+  articulation of the coracoids with the sternum. The humeral
+  articulation with the coracoid is unlike the condition shown
+  in other Ornithosaurs]
+
+There is no approach to this transverse position of the scapulae among
+birds. And while the form of the bones in the older genera of
+Ornithosaurs is singularly bird-like, the angular arrangement in this
+Cretaceous genus is obtained by closely approximating the articulations
+on the sternum, so that the coracoids extend outward as in reptiles,
+instead of forward as in birds; and the extremities of the scapulae
+similarly approximate towards each other. This rather recalls the
+relative positions of scapula and coracoid among crocodiles. If
+crocodile and bird had been primitive types of animals instead of
+surviving types, it might almost seem as though there had been a cunning
+and harmonious blending of one with the other in evolving this form of
+shoulder-girdle.
+
+
+THE FORE LIMB
+
+The bones of the fore limb, generally, correspond in length with the
+similar parts of the hind limb. The upper arm bone corresponds with the
+upper leg bone, and the fore-arm bone is as long as the fore-leg bone;
+then differences begin. The bones which correspond to the back of the
+hand in man, termed the metacarpus, are variable in length in
+Pterodactyles--sometimes very long and sometimes short. The wing
+metacarpal bone is always stout, and the others are slender. The
+extremity of the metacarpus was applied to the ground. Three small
+digits of the hand are developed from the three small metacarpal bones,
+and terminate in large claws.
+
+The great wing finger was bent backward, and only touched the ground
+where it fitted upon the wing metacarpal bone. It appears sometimes to
+have been as long as the entire vertebral column.
+
+Owing to the circumstance that the joint in the arm in Pterodactyles was
+not at the wrist as among birds, but between the metacarpus and the
+phalanges, it follows that the fore limb was longer than the hind limb
+when the metacarpus was long; but the difference would not interfere
+with the movements of the animal, either upon four feet or on two feet,
+for in bats and birds the disproportion in length is greater.
+
+
+HUMERUS OR UPPER ARM BONE
+
+The first bone in the fore-arm, the humerus, is remarkable chiefly for
+the compressed crescent form of its upper articular end, which is never
+rounded like the head of the upper arm bone in man, and secondly for the
+great development of the external process of bone near that end, termed
+the radial crest. Sir Richard Owen compared the bone to the humerus of
+both birds and crocodiles, but in its upper articular end the crocodile
+bone may be said to be more like a bird than it is like the
+Pterodactyle. In flying reptiles the articular surface next to the
+shoulder-girdle is somewhat saddle-shaped, being concave from side to
+side above and convex vertically, while most animals with which it can
+be compared have the articular head of the bone convex in both
+directions. A remarkable exception to this general rule is found in some
+fossil animals from South Africa, which, from resemblance to mammals in
+their teeth, have been termed Theriodonts. They sometimes have the head
+of the bone concave from side to side and convex in the vertical
+direction. To this condition Ornithorhynchus makes a slight
+approximation. The singular expansion of the structure called the radial
+crest finds no close parallel in reptiles, though Crocodiles have a
+moderate crest on the humerus in the same position; and in Theriodonts
+the radial crest extends much further down the shaft of the humerus. No
+bird has a radial crest of a similar kind, though it is prolonged some
+way down the shaft in Archaeopteryx. In Pterodactyles it sometimes
+terminates outward in a smooth, rounded surface, which might have been
+articular if any structure could have articulated with it. There is also
+a moderate expansion of the bone on the ulnar side in some
+Pterodactyles, so that the proximal end often incloses nearly
+three-fourths of an ovate outline. The termination of the radial crest
+is at the opposite end of this oval to the wider articular part of the
+head of the bone, in some specimens from the Cambridge Greensand. The
+radial crest is more extended in Rhamphorhynchus. All specimens of the
+humerus show a twist in the length of the bone, so that the end towards
+the fore-arm, which is wider than the shaft, makes a right angle with
+the radial crest on the proximal end, which is not seen in birds. The
+shaft of the humerus is always stouter than that of the femur, though
+different genera differ in this respect.
+
+The humerus in genera from rocks associated with the Chalk presents two
+modifications, chiefly seen in the characters of the distal end of the
+bone. One of these is a stout bone with a curiously truncated end where
+it joins the two bones of the fore-arm; and the other is more or less
+remarkable for the rounded form of the distal condyles. Both types show
+distinct articular surfaces. The inner one is somewhat oblique and
+concave, the outer one rounded; the two being separated by a concave
+channel, so that the ulna makes an oblique articulation with the bone as
+in birds, and the radius articulates by a more or less truncated or
+concave surface.
+
+  [Illustration: FIG. 41.  COMPARISON OF THE HUMERUS IN PTERODACTYLE AND
+  BIRD]
+
+
+ULNA AND RADIUS
+
+  [Illustration: FIG. 42.  COMPARISON OF THE BONES OF THE FORE-ARM IN
+  BIRD AND ORNITHOSAUR]
+
+The bones of the fore-arm are similar to each other in size, and if
+there be any difference between them the ulna is slightly the larger.
+There is some evidence that in Rhamphorhynchus the upper end of the ulna
+was placed behind the radius, probably in consequence of the mode of
+attachment of those bones to the humerus. The ulna abutted towards the
+inner and lower border, while the radius was towards the upper border,
+consequent upon the twist in the humerus. This condition corresponds
+substantially with the arrangement in birds, but differs from birds in
+the relatively more important part taken by the radius in making the
+articulation. The bones are compared in Dimorphodon with the Golden
+Eagle drawn of the same size (Fig. 42). In birds the ulna supports the
+great feathers of the wing, and this may account for the size of the
+bone. The ulna is best seen at its proximal end in the specimens from
+the Cambridge Greensand, where there is a terminal olecranon
+ossification forming an oblique articulation, which frequently comes
+away and is lost. It is sometimes well preserved, and indicated by a
+suture. The examples of ulna from the Lias show a slight expansion of
+the bone at both ends, and at the distal end toward the wrist the
+articulation is well defined, where the bone joins the carpus. The
+larger specimens of the bone are broken. The distal articular surface is
+only connected with the proximal end of the bone in small specimens: it
+always shows on the one margin a concavity, followed by a prominent
+boss, and an oblique articulation beyond the boss. On the side towards
+the radius, on the lower end of the shaft there is an angular ridge,
+which marks the line along which the ulna overlaps the radius. The
+lower end of the radius has a simple, slightly convex articulation,
+somewhat bean-shaped. No rotation of these bones on each other was
+possible as in man. There is a third bone in the fore-arm. This bone,
+named the pteroid, is commonly seen in skeletons from Solenhofen. It was
+regarded by Von Meyer as having supported the wing membrane in flight.
+Some writers have interpreted it as an essential part of the
+Pterodactyle skeleton, and Von Meyer thought that it might possibly
+indicate a fifth digit in the hand. The only existing structure at all
+like it is seen in the South African insectivorous mammal named
+_Chrysochloris capensis_, the golden mole, which also has three bones in
+the fore-arm, the third bone extending half-way up towards the humerus.
+In that animal the third bone appears to be behind the others and
+adjacent to the ulna. In the German fossils the pteroid articulated with
+a separate carpal or metacarpal bone, placed on the side of the arm
+adjacent to the radius, and the radius is always more inward than the
+ulna. If the view suggested by Von Meyer is adopted, this bone would be
+a first digit extending outward and backward towards the humerus. That
+view was adopted by Professor Marsh. It involves the interpretation of
+what has been termed the lateral carpal as the first metacarpal bone,
+which would be as short as that of a bird, but turned in the opposite
+direction backward. The first digit would then only carry one phalange,
+and would not terminate in a claw, but lie in the line of the tendon
+which supports the anterior wing membrane of a bird.
+
+The third bone in the fore-arm of Chrysochloris does not appear to
+correspond to a digit. The bone is on the opposite side of the arm to
+the similar bone of a Pterodactyle, and therefore cannot be the same
+structure in the Golden Mole. The interpretation which makes the pteroid
+bone the first digit has the merit of accounting for the fifth digit of
+the hand. All the structures of the hand are consistent with this view.
+The circumstance that the bone is rarely found in contact with the
+radius, but diverging from it, shows that it plays the same part in
+stretching the membrane in advance of the arm, that the fifth digit
+holds in supporting the larger wing membrane behind the arm.
+
+According to Professor Williston, the American toothless Pterodactyle
+Ornithostoma has but a single phalange on the corresponding first toe of
+the hind foot, and that bone he describes as long, cylindrical, gently
+curved, and bluntly pointed. There is some support for this
+interpretation; but I have not seen any English or German Pterodactyles
+with only one phalange in the first toe.
+
+The wing in Pterodactyles would thus be stretched between two fingers
+which are bent backward, the three intermediate digits terminating in
+claws.
+
+
+THE CARPUS
+
+The wrist bones in the reptilia usually consist of two rows. In
+Crocodiles, in the upper row there is a large inner and a small outer
+bone, behind which is a lunate bone, the remainder of the carpus being
+cartilaginous. Only one carpal is converted into bone in the lower row.
+It is placed immediately under the smaller upper carpal. In Chelonians,
+the turtle and tortoise group, the characters of the carpus vary with
+the family. In the upper row there are usually two short carpals, which
+may be blended, under the ulna; while the two under the radius are
+commonly united. The lower row is made up of several small bones.
+Lizards, too, usually have three bones in the proximal row and five
+smaller bones in the distal row.
+
+The correspondence of the distal carpals with the several metacarpal
+bones of the middle hand is a well-known feature of the structure of the
+wrist.
+
+Von Meyer remarks that the carpus is made up of two rows of small bones
+in the Solenhofen Pterodactyles; while in birds there is one row
+consisting of two bones. The structure of the carpus is not distinct in
+all German specimens; but in the short-tailed Solenhofen genera the
+bones in the two rows retain their individuality.
+
+In all the Cretaceous genera the carpal bones of each row are blended
+into a single bone, so that two bones are superimposed, which may be
+termed the proximal and distal carpals. One specimen shows by an
+indication of sutures the original division of the distal carpal into
+three bones; and the separated constituent bones are very rarely met
+with. Two bones of the three confluent elements contribute to the
+support of the wing metacarpal, and the third gives an articular
+attachment to the bone which extends laterally at the inner side of the
+carpus, which I now think may be the first metacarpal bone turned
+backward towards the humerus. The three component bones meet in the
+circular pneumatic foramen in the middle of the under side of the distal
+carpal. There is no indication of division of the proximal carpal in
+these genera into constituent bones.
+
+  [Illustration:  FIG. 43.  CARPUS FROM ORNITHOCHEIRUS
+  (Cambridge Greensand)]
+
+This condition is somewhat different from birds. In 1873 Dr. Rosenberg,
+of Dorpat, showed that there is in the bird a proximal carpal formed of
+two elements, and a distal carpal also formed of two elements. Therefore
+the two constituents of the distal carpal in the bird which blends in
+the mature animal with the metacarpus, forming the rounded pulley joint,
+may correspond with two of the three bones in the Cretaceous
+Pterodactyle _Ornithocheirus._
+
+The width of a proximal carpal rarely exceeds two inches, and that of a
+distal carpal is about an inch and three-quarters. Two such bones when
+in contact would not measure more than one inch in depth. The lower
+surface shows that the wing had some rotary movement upon the carpus
+outward and backward.
+
+
+METACARPUS
+
+  [Illustration: FIG. 44.  METACARPUS IN TWO ORNITHOSAURS]
+
+The metacarpus consists of bones which correspond to the back of the
+hand. The first digit of the hand in clawed animals has the metacarpal
+bone short, or shorter than the others. Among mammals metacarpal bones
+are sometimes greatly elongated; and a similar condition is found in
+Pterodactyles, in which the metacarpal bone may be much longer than the
+phalange which is attached to it. Two metacarpal bones appear to be
+singularly stouter than the others. The first bone of the first digit,
+if rightly determined, is much shorter than the others, and is, in fact,
+no longer than the carpus (Fig. 43). It is a flat oblong bone, attached
+to the inner side of the lower carpal, and instead of being prolonged
+distally in the same direction as the other metacarpal bones, is turned
+round and directed upward, so that its upper edge is flush with the base
+of the radius, and gives attachment to a bone which resembles a terminal
+phalange of the wing finger. According to this interpretation it is the
+first and only phalange in the first digit. The bone is often about half
+as long as the fore-arm, terminates upward in a point, is sometimes
+curved, and frequently diverges outward from the bones of the fore-arm,
+as preserved in the associated skeleton, being stretched towards the
+radial crest of the humerus. This mode of attachment of the supposed
+first metacarpal, which is true for all Cretaceous pterodactyles, has
+not been shown to be the same for all those from the Solenhofen Slate.
+There is no greater anomaly in this metacarpal and phalange on the
+inner side being bent backward, than there is in the wing finger being
+bent backward on the outer side. The three slender intervening digits
+extend forward between them, as though they were applied to the ground
+for walking.
+
+The bone which is usually known as the wing metacarpal is frequently
+stouter at the proximal end towards the carpus than towards the
+phalange. At the carpal end it is oblong and truncated, with a short
+middle process, which may have extended into the pit in the base of the
+carpal bone; while the distal terminal end is rounded exactly like a
+pulley. There is great difference in the length of the metacarpus. In
+the American genus Ornithostoma it is much longer than the fore-arm. In
+Rhamphorhynchus it is remarkably short, though perhaps scarcely so short
+as in Dimorphodon or in Scaphognathus. The largest Cretaceous examples
+are about two inches wide where they join the carpus. The bone is
+sometimes a little curved.
+
+Between the first and fifth or wing metacarpal are the three slender
+metacarpal bones which give attachment to the clawed digits. They bear
+much the same relation to the wing metacarpal that the large metatarsal
+of a Kangaroo has to the slender bones of the instep which are parallel
+to it.
+
+The facet for the wing metacarpal on the carpus is clearly recognised,
+but as a rule there is no surface with which the small metacarpals can
+be separately articulated. One or two exceptional specimens from the
+Cambridge Greensand appear to have not only surfaces for the wing
+metacarpal, but two much smaller articular surfaces, giving attachment
+to smaller metacarpals; while in one case there appears to be only one
+of these additional impressions. It is certain that all the animals from
+the Lias and Oolites have three clawed digits, but at present I have
+seen no evidence that there were three in the Cretaceous genera, though
+Professor Williston's statements and restoration appear to show that the
+toothless Pterodactyles have three. Another difference from the Oolitic
+types, according to Professor Williston, is in the length of the slender
+metacarpals of the clawed phalanges being about one-third that of the
+wing metacarpal, but this is probably due to imperfect ossification at
+the proximal end; for at the distal end the bones all terminated on the
+same level, showing that the four outer digits were applied to the
+ground to support the weight of the body. The corresponding bone in the
+Horse and Oxen is carried erect, so as to be in a vertical line with the
+bones of the fore-arm; and the same position prevails usually, though
+not invariably, with the corresponding bone in the hind limb, while in
+many clawed mammals the metacarpus and metatarsus are both applied upon
+the ground. In Pterodactyles the metatarsal bones are preserved in the
+rock in the same straight line with the smaller bones of the foot, or
+make an angle with the shin bone, leading to the conviction that the
+bones of the foot were applied to the ground as in Man, and sometimes as
+in the Dog, and were thus modified for leaping. Just as the human
+metacarpus is extended in the same line with the bones of the fore-arm,
+and the movement of jointing occurs where the fingers join the
+metacarpus, so Pterodactyles also had these bones differently modified
+in the fore and hind limbs for the functions of life. The result is to
+lengthen the fore limb as compared with the hind limb by introducing
+into it an elevation above the ground which corresponds to the length of
+the metacarpus, always supposing that the animal commonly assumed the
+position of a quadruped when upon the earth's surface.
+
+This position of the metacarpus is a remarkable difference from Birds,
+because when the bird's wing is at rest it is folded into three
+portions. The upper arm bone extends backward, the bones of the fore-arm
+are bent upon it so as to extend forward, and then at the wrist the
+third portion, which includes the metacarpus and finger bones, is bent
+backward. So that the metacarpus in the Pterodactyle differs from birds
+in being in the same line as the bones of the fore-arm, whereas in birds
+it is in the same line with the digit bones of the hand. It is worthy of
+remark that in Bats, which are so suggestive of Pterodactyles in some
+features of the hand, the metacarpals and phalanges are in the same
+straight line; so that in this respect the bat is more like the bird.
+But Pterodactyles in the relation of these bones to flight are quite
+unlike any other animal, and have nothing in common with the existing
+animals named Reptiles.
+
+
+THE HAND
+
+From what has just been said it follows that the construction of the
+hand is unique. It may be contrasted with the foot of a bird. The bone
+which is called, in the language of anatomists, the tarso-metatarsus,
+and is usually free from feathers and covered with skin, is commonly
+carried erect in birds, so that the whole body is supported upon it; and
+from it the toes diverge outward. It is formed in birds of three
+separate bones blended together. In the fore limb of the Pterodactyle
+the metacarpus has the same relation to the bones of the fore-arm that
+the metatarsus has to the corresponding bones of the leg in a bird. But
+the three metacarpal bones in the Pterodactyle remain distinct from each
+other, perhaps because the main work of that region of the skeleton has
+devolved upon the digit called the wing finger, which is not recognised
+in the bird. In the Pterodactyles from the Solenhofen Slate there is a
+progressive number of phalanges in the three small digits of the hand,
+which were applied to the ground. This number in the great majority of
+species follows the formula of two bones in the first, three bones in
+second, and four in the third; so that in the innermost of the clawed
+digits only one bone intervenes between the metacarpal and the claw. The
+fingers slightly increase in length with increase in number of bones
+which form them.
+
+  [Illustration: FIG. 45.  CLAW PHALANGE FROM THE HAND IN
+  ORNITHOCHEIRUS. (Half natural size)]
+
+  [Illustration: FIG. 46.  METACARPUS AND DIGITS OF THE HAND IN BIRDS
+  WITH CLAWS]
+
+The terminal claw bones are unlike the claws of Birds or Reptiles. They
+are compressed from side to side, and extremely deep and strong, with
+evidence of powerful attachment for ligaments, so that they rather
+resemble in their form and large size the claws of some of the
+carnivorous fossil reptiles, often grouped as Dinosauria, such as have
+been termed Aristosuchus and Megalosaurus. In the hand of the Ostrich
+the first and second digits terminate in claws, while the third is
+without a claw. But these claws of the Ostrich and other birds are
+slender, curved, and rather feeble organs. In the Archaeopteryx, a fossil
+bird which agrees with the Pterodactyles in retaining the separate
+condition of the metacarpal bones and in having the same number of
+phalanges in two of the fingers of the fore limb, the terminal claws are
+rather more compressed from side to side, and stronger than in the
+Ostrich, but not nearly so strong as in the Pterodactyle. The
+Archaeopteryx differs from the Pterodactyle in having no trace of a wing
+finger. The first metacarpal bone is short, as in all birds; and the
+first phalange scarcely lengthens that segment of the first digit of the
+Bird's hand to the same length as the other metacarpal bones. It
+therefore was not bent backward like the first digit in Pterodactyles.
+The wing finger, from which the genius of Cuvier selected the scientific
+name--Pterodactyle--for these fossils, yields their most distinctive
+character. It is a feature which could only be partly paralleled in the
+Bat, by making changes of structure which would remove every support to
+the wing but the outermost digit of that animal's hand. In the Bat's
+hand the membrane for flight is extended chiefly by four diverging
+metacarpal bones. There are only two or three phalanges in each digit in
+its four wing fingers. In Pterodactyles the metacarpal bones are, as we
+have seen, arranged in close contact, and take no part in stretching the
+wing.
+
+
+THE WING FINGER
+
+In Birds there is nothing whatever to represent the wing finger of the
+Pterodactyle, for it is an organ external to the finger bones of the
+bird, and contains four phalanges. The first phalange is quite different
+from the others. Its length is astonishing when compared with the small
+phalanges of the clawed fingers. The articular surface, which joins on
+to the wing metacarpal bone, is a concave articulation, which fits the
+pulley in which that bone ends. The pulley articulation admits of an
+extension movement in one direction only. Many specimens show the wing
+finger to be folded up so as to extend backward. The whole finger is
+preserved in other specimens straightened out so as to be in line with
+the metacarpus. This condition is well seen in Professor Marsh's
+specimen of Rhamphorhynchus, which has the wing membrane preserved, in
+which all bones of the fore-arm metacarpus and wing finger are extended
+in a continuous curve. The outer surface of the end of the first bone of
+the wing finger overlaps the wing metacarpal, so that a maximum of
+strength and resistance is provided in the bony structures by which the
+wing is supported. There is, therefore, in flight only one angular bend
+in the limb, and that is between the upper arm bone and the fore-arm.
+
+An immense pneumatic foramen is situate in a groove on the under side of
+the upper end of the first phalange in Ornithocheirus, but is absent in
+specimens from the Kimeridge clay. This bone is long and stout. It
+terminates at the lower end in an obliquely truncated articular surface.
+Specimens occur in the Cambridge Greensand which are 2 inches broad at
+the upper end and nearly 1-1/2 inch wide at the lower end. An imperfect
+bone from the Chalk is 14-1/2 inches long. The bones are all flattened.
+Specimens from the Chalk of Kansas at Munich are 28 inches long. The
+second phalange is concave at the upper articular end and convex in the
+longer direction at the lower end. The articular points of union between
+the several phalanges form prominences on the under side of the finger
+in consequence of the adjacent bones being a little widened at their
+junction. It should be mentioned that there is a proximal epiphysis or
+separate bone to the first phalange, adjacent to the pulley joint of the
+metacarpal bone, which is like the separate olecranon process of the
+ulna of the fore-arm. It sometimes comes away in specimens from the
+Chalk and Cambridge Greensand, leaving a large circular pit with a
+depressed narrow border. On the outer side of this process is a rounded
+boss, which may possibly have supported the bone, if it were applied to
+the ground with the wing folded up, like the wing of a Bat directed
+upward and backward at the animal's side.
+
+The four bones of the wing finger usually decrease progressively in
+length, so that in Rhamphorhynchus, in which the length of the animal's
+head only slightly exceeds 3-1/2 inches, the first phalange is nearly as
+long, the second phalange is about 3-1/4 inches, the third 2-3/4 inches,
+and the fourth a little over 2 inches. Thus the entire length of the
+four phalanges slightly exceeds 11 inches, or rather more than three
+times the length of the head. But the fore-arm and metacarpus in this
+type only measure 3 inches. Therefore the entire spread of wings could
+not have been more than 2 feet 9 inches.
+
+The largest Ornithosaur in which accurate measurements have been made is
+the toothless Pterodactyle Ornithostoma, also named Pteranodon, from
+North America. In that type the head appears to have been about 3 or 4
+feet long, and the wing finger exceeded 5 feet; while the length of the
+fore-arm and metacarpus exceeded 3 feet. The width of the body would not
+have been more than 1 foot. The length of the short humerus, which was
+about 11 inches, did not add greatly to the stretch of the wing; so that
+the spread of the wings as stretched in flight may be given as probably
+not exceeding 17 or 18 feet. A fine example of the wing bones of this
+animal quite as large has been obtained by the (British Museum Natural
+History). Many years ago, on very fragmentary materials, I estimated the
+wings in the English Cretaceous Ornithocheirus as probably having a
+stretch of 20 feet in the largest specimens, basing the calculation
+partly upon the extent of the longest wings in existing birds relatively
+to their bones, and partly upon the size of the largest associated bones
+which were then known.
+
+
+
+
+CHAPTER XII
+
+EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS
+
+
+Such are the more remarkable characters of the bones in a type of animal
+life which was more anomalous than any other which peopled the earth in
+the Secondary Epoch of geological time. Its skeleton in different parts
+resembles Reptiles, Birds, and Mammals; with modifications and
+combinations so singular that they might have been deemed impossible if
+Nature's power of varying the skeleton could be limited. Since
+Ornithosaurs were provided with wings, we may believe the animals to
+some extent to have resembled birds in habit. Their modes of progression
+were more varied, for the structures indicate an equal capacity for
+movement on land as a biped, or as a quadruped, with movement in the
+air. There is little evidence to support the idea that they were usually
+aquatic animals. The majority of birds which frequent the water have
+their bodies stored with fat and the bones of their extremities filled
+with marrow. And a bird's marrow bones are stouter and stronger than
+those which are filled with air. There are few, if any, bones of
+Pterodactyles so thick as to suggest the conclusion that they contained
+marrow, and the bones of the extremities appear to have been
+constructed on the lightest type found among terrestrial birds. Their
+thinness, except in a few specimens from the Wealden rocks, is
+marvellous; and all the later Pterodactyles show the arrangement, as in
+birds, by which air from the lungs is conveyed to the principal bones.
+No Pterodactyle has shown any trace of the web-footed condition seen in
+birds which swim on the water, unless the diverging bones of the hind
+foot in Rhamphorhynchus supports that inference. The bones of the hind
+foot are relatively small, and if it were not that a bird stands easily
+upon one foot, might be considered scarcely adequate to support the
+animal in the position which terrestrial birds usually occupy. Yet, as
+compared with the length and breadth of the foot in an Ostrich, the toes
+of an Ornithosaur are seen to be ample for support. These facts appear
+to discourage the idea that the animals were equally at home on land and
+water, and in air.
+
+Some light may be thrown upon the animal's habits by the geological
+circumstances under which the remains are found. The Pterodactyle named
+Dimorphodon, from the Lias of the south of England, is associated with
+evidences of terrestrial land animals, the best known of which is
+Scelidosaurus, an armoured Dinosaur adapted by its limbs for progression
+on land. And the Pterodactyle Campylognathus, from the Lias of Whitby,
+is associated with trunks of coniferous trees and remains of Insects. So
+that the occurrence of Pterodactyles in a marine stratum is not
+inconsistent with their having been transported by streams from off the
+old land surface of the Lias, on which coniferous trees grew and
+Dinosaurs lived.
+
+Similar considerations apply to the occurrence of the Rhamphocephalus in
+the Stonesfield Slate of England. The deposit is not only formed in
+shallow water, but contains terrestrial Insects, a variety of land
+plants, and many Reptiles and other animals which lived upon land. The
+specimens from the Purbeck beds, again, are in strata which yield a
+multitude of the spoils of a nearly adjacent land surface; while the
+numerous remains found in the marine Solenhofen Slate in Germany are
+similarly associated with abundant evidences of varied types of
+terrestrial life. The evidence grows in force from its cumulative
+character. The Wealden beds, which yield many terrestrial reptiles and
+so much evidence of terrestrial vegetation, and shallow-water conditions
+of disposition, have afforded important Pterodactyle remains from the
+Isle of Wight and Sussex.
+
+The chief English deposit in which these fossils are found, the Upper
+Greensand, has afforded thousands of bones, battered and broken on a
+shore, where they have lain in little associated groups of remains,
+often becoming overgrown with small marine shells. Side by side with
+them are found bones of true terrestrial Lizards and Crocodiles of the
+type of the Gavial of the Indian rivers, many terrestrial Dinosaurs, and
+other evidences of land life, including fossil resins, such as are met
+with in the form of amber or copal at the present day.
+
+The great bones of Pterodactyles found in the Chalk of Kent, near
+Rochester, became entombed, beyond question, far from a land surface.
+There is nothing to show whether the animals died on land and were
+drifted out to sea like the timber which is found water-logged and
+sunken after being drilled by the ship-worm (Teredo) of that epoch.
+Seeing the power of flight which the animal possessed, storms may have
+struck down travellers from time to time, when far from land.
+
+Evidence of habit of another kind may be found in their teeth. They are
+brightly enamelled, sharp, formidable; and are frequently long,
+overlapping the sides of the jaws. They are organs which are often
+better adapted for grasping than for tearing, as may be seen in the
+inclined teeth of Rhamphocephalus of the Stonesfield Slate; and better
+adapted for killing than tearing, from their piercing forms and cutting
+edges, in genera like Ornithocheirus of the Greensand. The manner in
+which the teeth were implanted and carried is better paralleled by the
+fish-eating crocodile of Indian rivers than by the flesh-eating
+crocodiles, or Muggers, which live indifferently in rivers and the sea.
+As the Kingfisher finds its food (see Fig. 20) from the surface of the
+water without being in the common sense of the term a water bird, so
+some Pterodactyles may have fed on fish, for which their teeth are well
+adapted, both in the stream and by the shore.
+
+A Pterodactyle's teeth vary a good deal in appearance. The few large
+teeth in the front of the jaw in Dimorphodon, associated with the many
+small vertical teeth placed further backward, suggest that the taking of
+food may have been a process requiring leisure, since the hinder teeth
+adapted to mincing the animal's meat are extremely small. The way in
+which the teeth are shaped and arranged differs with the genera. In
+Pterodactylus they are short and broad and few, placed for the most part
+towards the front of the jaws. Their lancet-shaped form indicates a
+shear-like action adapted to dividing flesh. In the associated genus
+Rhamphorhynchus the teeth are absent from the extremity of the jaw, are
+slender, pointed, spaced far apart, and extend far backward. When the
+jaws of the Rhamphorhynchus are brought together there is always a gap
+between them in front, which has led to belief that the teeth were
+replaced by some kind of horny armature which has perished. In the
+long-nosed English type of Ornithocheirus the jaws are compressed
+together, so that the teeth of the opposite sides are parallel to each
+other, with the margins well filled with teeth, which are never in close
+contact, though occasionally closer and larger in front, in some of the
+forms with thick truncated snouts.
+
+It is not the least interesting circumstance of the dentition of
+Pterodactyles that, associated in the same deposits with these most
+recent genera with teeth powerfully developed, there is a genus named
+Ornithostoma from the resemblance of its mouth to that of a bird in
+being entirely devoid of teeth. It is scarcely possible to distinguish
+the remains of the toothed and toothless skeletons except in the dentary
+character of the jaws. There is no evidence that the toothless types
+ever possessed a tooth of any sort. They were first found in fragments
+in England in the Cambridge Greensand, but were afterwards met with in
+great abundance in the Chalk of Kansas, where the same animals were
+named Pteranodon. A jaw so entirely bird-like suggests that the
+digestive organs of Pterodactyles may in such toothless forms at least
+have been characterised by a gizzard, which is so distinctive of Birds.
+The absence of teeth in the Great Ant-eater and some other allied
+Mammals has transferred the function which teeth usually perform to the
+stomach, one part of which becomes greatly thickened and muscular,
+adapting itself to the work which it has to perform. It is probable that
+the gizzard may be developed in relation to the necessities which food
+creates, since even Trout, feeding on the shell-fish in some Irish
+lochs, acquire such a thickened muscular stomach, and a like
+modification is recorded in other fishes as produced by food.
+
+Closely connected with an animal's habits is the protection to the body
+which is afforded by the skin. In Pterodactyles the evidence of the
+condition of the skin is scanty, and mostly negative. Sometimes the
+dense, smooth texture of the jaw bones indicates a covering like the
+skin of a Lizard or the hinder part of the jaw of a Bird. Some jaws from
+the Cambridge Greensand have the bone channeled over its surface by
+minute blood vessels which have impressed themselves into the bone more
+easily than into its covering. Thus in the species of Ornithocheirus
+distinguished as _microdon_ the palate is absolutely smooth, while in
+the species named _machaerorhynchus_ it is marked by parallel impressed
+vascular grooves which diverge from the median line. This condition
+clearly indicates a difference in the covering of the bone, and that in
+the latter species the covering had fewer blood vessels and more horny
+protection than in the other. The tissue may not have been of firmer
+consistence than in the palate of Mammals. The extremity of the beak is
+often as full of blood vessels as the jaw of a Turtle or Crocodile.
+
+
+COVERING OF THE BODY
+
+There is no trace even in specimens from the Solenhofen or Stonesfield
+Slate of any covering to the body. There are no specimens preserved like
+mummies, and although the substance of the wings is found there is no
+trace of fur or feathers, bones, or scales on the skin. The only example
+in which there is even an appearance suggesting feathers is in the
+beautiful Scaphognathus at Bonn, and upon portions of the wing membrane
+of that specimen are preserved a very few small short and apparently
+tubular bodies, which have a suggestive resemblance to the quills of
+small undeveloped feathers. Such evidences have been diligently sought
+for. Professor Marsh, after examining the wing membranes of his specimen
+of Rhamphorhynchus from Solenhofen, stated that the wings were partially
+folded and naturally contracted into folds, and that the surface of the
+tissue is marked by delicate striae, which might easily be taken at first
+sight for a thin coating of hair. Closer investigation proved the
+markings to be minute wrinkles on the under surface of the wing
+membrane. This negative evidence has considerable value, because the
+Solenhofen Slate has preserved in the two known examples of the bird
+Archaeopteryx beautiful details of the structure of the larger feathers
+concerned in flight. It has preserved many structures far more delicate.
+There is, therefore, reason for believing that if the skin had possessed
+any covering like one of those found in existing vertebrate animals, it
+could scarcely have escaped detection in the numerous undisturbed
+skeletons of Pterodactyles which have been examined.
+
+The absence of a recognisable covering to the skin in a fossil state
+cannot be accepted as conclusive evidence of the temperature, habits, or
+affinities of the animal. Although Mammalia are almost entirely clothed
+with dense hair, which has never been found in a recognisable condition
+in a fossil state in any specimen of Tertiary age, one entire order, the
+Cetacea, show in the smooth hairless skins of Whales and Porpoises that
+the class may part with the typical characteristic covering without loss
+of temperature and without intelligible cause. That the absence of hair
+is not due to the aquatic conditions of rivers or sea is proved by other
+marine Mammals, like Seals, having the skin clothed with a dense growth
+of hair, which is not surpassed in any other order. The fineness of the
+growth of hair in Man gives a superficial appearance of the skin being
+imperfectly clothed, and a similar skin in a fossil state might give the
+impression that it was devoid of hair. There are many Mammals in which
+the skin is scantily clothed with hair as the animal grows old. Neither
+the Elephant nor the Armadillo in a fossil state would be likely to have
+the hair preserved, for the growth is thin on the bony shields of the
+living Armadilloes. Yet the difficulty need be no more inherent in the
+nature of hair than in that of feathers, since the hair of the Mammoth
+and Rhinoceros has been completely preserved upon their skins in the
+tundras of Siberia, densely clothing the body. This may go to show that
+the Pterodactyle possessed a thin covering of hair, or, more probably,
+that hair was absent. Since Reptiles are equally variable in the
+clothing of the skin with bony or horny plates, and in sometimes having
+no such protection, it may not appear singular that the skin in
+Ornithosaurs has hitherto given no evidence of a covering. From analogy
+a covering might have been expected; feathers of Birds and hair of
+Mammals are non-conducting coverings suited to arrest the loss of heat.
+
+With the evidence, such as it is, of resemblance of Ornithosaurs to
+Birds in some features of respiration and flight, a covering to the skin
+might have been expected. Yet the covering may not be necessary to a
+high temperature of the blood. Since Dr. John Davy made his observations
+it has been known that the temperature of the Tunny, above 90 deg.
+Fahrenheit, is as warm as the African scaly ant-eater named the
+Pangolin, which has the body more amply protected by its covering. This
+illustration also shows that hot blood may be produced without a
+four-celled heart, with which it is usually associated, and that even if
+the skin in Pterodactyles was absolutely naked an active life and an
+abundant supply of blood could have given the animal a high temperature.
+
+The circumstance that in several individuals the substance of the wing
+membrane is preserved would appear to indicate either that it was
+exceptionally stout when there would have been small chance of resisting
+decomposition, or that its preservation is due to a covering which once
+existed of fur or down or other clothing substance, which has proved
+more durable than the skin itself.
+
+  [Illustration: FIG. 48.  REMAINS OF DIMORPHODON FROM THE LIAS OF LYME
+  REGIS
+
+  SHOWING THE SKULL, NECK, BACK AND SOME OF THE LONGER BONES OF THE
+  SKELETON
+
+  _From a slab in the British Museum (Natural History)_]
+
+
+
+
+CHAPTER XIII
+
+ANCIENT ORNITHOSAURS FROM THE LIAS
+
+
+Cuvier's discourse on the revolutions of the Earth made the Pterodactyle
+known to English readers early in the nineteenth century. Dr. Buckland,
+the distinguished professor of Geology at Oxford, discovered in 1829 a
+far larger specimen in the Lias of Lyme Regis, and it became known by a
+figure published by the Geological Society, and by the description in
+his famous Bridgewater Treatise, p. 164. This animal was tantalising in
+imperfect preservation. The bones were scattered in the clay, so as to
+give no idea of the animal's aspect. Knowledge of its limbs and body has
+been gradually acquired; and now, for some years, the tail and most
+parts of the skeleton have been well known in this oldest and most
+interesting British Pterodactyle.
+
+Sir Richard Owen after some time separated the fossil as a distinct
+genus, named Dimorphodon; for it was in many ways unlike the
+Pterodactyles described from Bavaria. The name Dimorphodon indicated the
+two distinct kinds of teeth in the jaws, a character which is still
+unparalleled among Pterodactyles of newer age. There are a few large
+pointed, piercing and tearing teeth in the front of the jaws, with
+smaller teeth further back, placed among the tearing teeth in the upper
+jaw; while in the lower jaw the small teeth are continuous, close-set,
+and form a fine cutting edge like a saw.
+
+  [Illustration: FIG. 49.  LEFT SIDE OF DIMORPHODON (RESTORED) AT REST]
+
+The Dimorphodon has a short beak, a deep head, and deep lower jaw, which
+is overlapped by the cheek bones. The side of the head is occupied by
+four vacuities, separated by narrow bars of bone. First, in front, is
+the immense opening for the nostril, triangular in form, with the long
+upper side following the rounded curve of the face. A large triangular
+opening intervenes between the nose hole and the eye hole, scarcely
+smaller than the former, but much larger than the orbit of the eye. The
+eye hole is shaped like a kite or inverted pear. Further back still is a
+narrower vertical opening known as the lateral or inferior temporal
+vacuity. The back of the head is badly preserved. The two principal
+skulls differ in depth, probably from the strains under which they were
+pressed flat in the clay. A singular detail of structure is found in the
+extremity of the lower jaw, which is turned slightly downward, and
+terminates in a short toothless point. The head of Dimorphodon is
+about eight inches long.
+
+  [Illustration: FIG. 50.  DIMORPHODON MACRONYX
+  RESTORED FORM OF THE ANIMAL]
+
+The neck bones are of suitable stoutness and width to support the head.
+The bones are yoked together by strong processes. The neck was about 6
+inches long, did not include more than seven bones, and appeared short
+owing only to the depth and size of the head. The length of the backbone
+which supported the ribs was also about 6 inches. Its joints are
+remarkably short when compared with those of the neck. The tail is about
+20 inches long.
+
+The extreme length of the animal from the tip of the nose to the end of
+the tail may have been 3 feet 4 inches, supposing it to have walked on
+all fours in the manner of a Reptile or Mammal. This may have been a
+common position, but Dimorphodon may probably also have been a biped.
+Before 1875, when the first restoration appeared in the _Illustrated
+London News_, the legs had been regarded as too short to have supported
+the animal, standing upon its hind limbs. They are here seen to be well
+adapted for such a purpose. The upper leg bone is 3-1/4 inches long, the
+lower leg bone is 4-1/2 inches long, and the singularly strong instep
+bones are firmly packed together side by side as in a leaping or jumping
+Mammal, and measure 1-1/2 inches in length. Dimorphodon differs from
+several other Pterodactyles in having the hind limb provided with a
+fifth outermost short instep bone, to which two toe bones are attached.
+These bones are elongated in a way that may be compared, on a small
+scale, with the elongation of the wing finger in the fore limb. The
+digit was manifestly used in the same way as the wing finger, in partial
+support of a flying membrane, though its direction may have been upward
+and outward, rather than inward. There is no evidence of a pulley joint
+between the metatarsal and the adjacent phalange.
+
+The height of the Dimorphodon, standing on its hind legs in the position
+of a Bird, with the wings folded upon the body in the manner of a Bird,
+was about 20 inches. An ungainly, ill-balanced animal in aspect, but not
+more so than many big-headed birds, and probably capable of resting upon
+the instep bones as many birds do. The chief point of variation from the
+Pterodactyle wing is in the relative length of the metacarpus in
+Dimorphodon. It is shorter than the other bones in the wing, never
+exceeding 1-1/2 inches. The total length of all the arm bones down to
+the point where the metacarpus might have touched the ground, or where
+the wing finger is bent upon it, is about 9 inches, which gives a length
+of less than 6 inches below the upper arm bone. The four bones of the
+wing finger measure, from the point where the first bone bends upon the
+metacarpus, less than 18 inches. So that the wings could only have been
+carried in the manner of the wings of a Bat, folded at the side and
+directed obliquely over the back when the animal moved on all fours. Its
+body would appear to have been raised high above the ground, in a manner
+almost unparalleled in Reptiles, and comparable to Birds and Mammals.
+Dimorphodon is to be imagined in full flight, with the body extended
+like that of a Bird, when the wings would have had a spread from side to
+side of about 4 feet 4 inches. As in other animals of this group, the
+three claws on the front feet are larger than the similar four claws on
+the hind feet; as though the fingers might have functions in grasping
+prey, which were not shared by the toes.
+
+  [Illustration: FIG. 51.  DIMORPHODON MACRONYX WALKING AS A QUADRUPED
+  RESTORATION OF THE SKELETON]
+
+The restorations give faithful pictures of the skeleton, and the form of
+the body is built upon the indications of muscular structure seen in the
+bones.
+
+A second English Pterodactyle is found in the Upper Lias of Whitby. It
+is only known from an imperfect skull, published in 1888. It has the
+great advantage of preserving the bones in their natural relations to
+each other, and with a length of head probably similar to Dimorphodon
+shows that the depth at the back of the eye was much less; and the skull
+wants the arched contour of face seen in Dimorphodon. The head has the
+same four lateral vacuities, but the nostril is relatively small and
+elongated, extending partly above the oval antorbital opening, which was
+larger. There is thus a difference of proportion, but it is precisely
+such as might result from the species having the skull flatter. The head
+is easily distinguished by the small nostril, which is smaller than the
+orbit of the eye. The animal is referred to another genus. The quadrate
+bones which give attachment to the lower jaw send a process inward to
+meet the bones of the palate, which differ somewhat from the usual
+condition. Two bony rods extend from the quadrate bones backward and
+upward to the sphenoid, and two more slender bones extend from the
+quadrate bones forward, and converge in a #V#-shape, to define the
+division between the openings of the nostrils on the palate. The
+#V#-shaped bone in front is called the vomer, while the hinder part is
+called pterygoid. The bones that extend backward to the sphenoid are not
+easily identified. This animal is one of the most interesting of
+Pterodactyles from the very reptilian character exhibited in the back of
+the head, which appears to be different from other specimens, which are
+more like a bird in that region. Yet underneath this reptilian aspect,
+with the bony bar at the side of the temporal region of the head formed
+by the squamosal and quadrate bones, defining the two temporal vacuities
+as in Reptiles, a mould is preserved of the cavity once occupied by the
+brain, showing the chief details of structure of that organ, and proving
+that in so far as it departs from the brain of a Bird it appears to
+resemble the brain of a Mammal, and is unlike the brain of a Reptile.
+
+The Pterodactyles from the Lias of Germany are similar to the English
+types, in so far as they can be compared. In 1878 I had the opportunity
+of studying those which were preserved in the Castle at Banz, which
+Professor Andreas Wagner, in 1860, referred to the new genus
+Dorygnathus. The skull is unknown, but the lower jaw, 6-1/2 inches long,
+is less than 2-1/2 inches wide at the articulation with the quadrate
+bone in the skull. The depth of the lower jaw does not exceed 1/4 inch,
+so that it is in marked contrast to Buckland's Dimorphodon. The
+symphysis, which completely blends the rami of the jaw, is short. As far
+as it extends it contains large tearing teeth, followed by smaller teeth
+behind, like those of Dimorphodon. But this German fossil appears to
+differ from the English type in having the front of the lower jaw, for
+about 3/4 inch, compressed from side to side into a sharp blade or
+spear, more marked than in any other Pterodactyle, and directed _upward_
+instead of downward as in Dimorphodon. Nearly all the measurements in
+the skeleton are practically identical with those of the English
+Dimorphodon, and extend to the jaw, humerus, ulna and radius, wing
+metacarpal, first phalange of the wing finger. The principal bones of
+the hind limb appear to be a little shorter; but the scapula and
+coracoid are slightly larger. All these bones are so similar in form to
+Dimorphodon that they could not be separated from the Lyme Regis
+species, if they were found in the same locality.
+
+  [Illustration: FIG. 52.  DIMORPHODON MACRONYX WALKING AS A BIPED
+  _Based chiefly on remains in the British Museum_]
+
+  [Illustration: FIG. 53.  LOWER JAW OF DORYGNATHUS SEEN FROM BELOW
+
+  From the Lower Lias of Germany, showing the spear in front of the
+  tooth sockets]
+
+Just as the Upper Lias in England has yielded a second Pterodactyle, so
+the Upper Lias in Germany has yielded a skeleton, to which Felix
+Plieninger, in 1894, gave the name Campylognathus. It is an instructive
+skeleton, with the head much smaller than in Dimorphodon, being less
+than 6 inches long, but, unfortunately, broken and disturbed. A lower
+jaw gives the length 4-1/2 inches. Like the other Pterodactyles from
+the Lias, it has the extremity of the beak toothless, with larger teeth
+in the region of the symphysis in front and smaller teeth behind. The
+jaw is deeper than in the Banz specimen from the Lower Lias, but not so
+deep as in Dimorphodon. The teeth of the upper jaw vary in size, and
+there appears to be an exceptionally large tooth in the position of the
+Mammalian canine at the junction of the bones named maxillary and
+intermaxillary.
+
+The nasal opening is small and elongated, as in the English specimen
+from Whitby. As in that type there is little or no indication of the
+convex contour of the face seen in Dimorphodon.
+
+The neck does not appear to be preserved. In the back the vertebrae are
+about 3/10 inch long, so that twelve, which is the usual number, would
+only occupy a length of a little more than 3-1/2 inches. The tail is
+elongated like that of Dimorphodon, and bordered in the same way by
+ossified ligaments. There are thirty-five tail vertebrae. Those which
+immediately follow the pelvis are short, like the vertebrae of the back.
+But they soon elongate, and reach a maximum length of nearly 1-1/2
+inches at the eighth, and then gradually diminish till the last scarcely
+exceeds 1/8 inch in length. The length of the tail is about 22 inches;
+this appears to be an inch or two longer than in Dimorphodon. The
+longest rib measures 2-1/2 inches, and the shortest 2 inches. These ribs
+probably were connected with the sternum, which is imperfectly
+preserved.
+
+  [Illustration: FIG. 54.  DIMORPHODON MACRONYX
+  SHOWING THE MAXIMUM SPREAD OF THE WING MEMBRANES]
+
+The bones of the limbs have about the same length as those of
+Dimorphodon, so far as they can be compared, except that the ulna and
+radius are shorter. The wing metacarpal is of about the same length, but
+the first phalange of the wing finger measures 6-1/4 inches, the second
+is about 8-1/4 inches, the third 6-1/2 inches, and the fourth 4-3/4
+inches; so that the total length of the wing finger was about half an
+inch short of 2 feet. One character especially deserves attention in the
+apparent successive elongation of the first three phalanges in the wing
+finger in Dimorphodon. The third phalange is the longest in the only
+specimen in which the finger bones are all preserved. Usually the first
+phalange is much longer than the second, so that it is a further point
+of interest to find that this German type shares with Dimorphodon a
+character of the wing finger which distinguishes both from some members
+of the group by its short first phalange.
+
+  [Illustration: FIG. 55.  THE LEFT SIDE OF THE PELVIS OF DIMORPHODON
+  SHOWING THE TWO PREPUBIC BONES]
+
+The pelvis is exceptionally strong in Campylognathus, and although it is
+crushed the bones manifestly met at the base of the ischium, while the
+pubic bones were separated from each other in front. The bones of the
+hind limb are altogether shorter in the German fossil than in
+Dimorphodon, especially in the tibia; but the structure of the
+metatarsus is just the same, even to the short fifth metatarsal with its
+two digits, only those bones are extremely short, instead of being
+elongated as in Dimorphodon. It is therefore convenient, from the
+different proportions of the body, that Campylognathus may be separated
+from Dimorphodon; but so much as is preserved of the English specimen
+from the Upper Lias of Whitby rather favours the belief that our species
+should also be referred to Campylognathus, which had not been figured
+when the Whitby skull was referred to Scaphognathus by Mr. Newton. It
+may be doubtful whether there is sufficient evidence to establish the
+distinctness of the other German genus Dorygnathus, though it may be
+retained pending further knowledge.
+
+In these characters are grounds for placing the Lias Pterodactyles in a
+distinct family, the Dimorphodontidae, as was suggested in 1870. This
+evidence is found in the five metatarsal bones, of which four are in
+close contact, the middle two being slightly the longest, so as to
+present the general aspect of the corresponding bones in a Mammal rather
+than a Bird. Secondly, the very slender fibula, prolonged down the
+length of the shin bone, which ends in a rounded pulley like the
+corresponding bone of a Bird. Thirdly, the great elongation of the third
+wing phalange. Fourthly, the prolongation of the coracoid bone beyond
+the articulation for the humerus, as in a Bird. And the toothless,
+spear-shaped beak, and jaw with large teeth in front and small teeth
+behind, are also distinctive characters.
+
+
+
+
+CHAPTER XIV
+
+ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS
+
+
+RHAMPHOCEPHALUS
+
+THE Stonesfield Slate in England, which corresponds in age with the
+lower part of the Great or Bath Oolite, yields many evidences of
+terrestrial life--land plants, insects, and mammals--preserved in a
+marine deposit. A number of isolated bones have been found of
+Pterodactyles, some of them indicating animals of considerable size and
+strength. The nature of the limestone was unfavourable to the
+preservation of soft wing membranes, or even to the bones remaining in
+natural association. Very little is known of the head of
+Rhamphocephalus. One imperfect specimen shows a long temporal region
+which is wide, and a very narrow interspace between the orbits; with a
+long face, indicated by the extension of narrow nasal bones. The lower
+jaw has an edentulous beak or spear in front, which is compressed from
+side to side in the manner of the Liassic forms, but turned upward
+slightly, as in Dorygnathus or Campylognathus. Behind this extremity are
+sharp, tall teeth, few in number, which somewhat diminish in size as
+they extend backward, and do not suddenly change to smaller series, as
+in the Lias genera. A few small vertebrae have been found, indicating the
+neck and back. The sacrum consists of five vertebrae. One small example
+has a length of only an inch. It is a little narrower behind than in
+front, and would be consistent with the animal having had a long tail,
+which I believe to have been present, although I have not seen any
+caudal vertebrae. The early ribs are like the early ribs of a Crocodile
+or Bird in the well-marked double articulation. The later ribs appear to
+have but one head. #V#-shaped abdominal ribs are preserved. Much of the
+animal is unknown. The coracoid seems to have been directed forward,
+and, as in a bird, it is 2-1/2 inches long. The humerus is 3-1/2 inches
+long, and the fore-arm measured 6 inches, so that it was relatively
+longer than in Dimorphodon. The metacarpus is 1-3/4 inches long. The
+wing finger was exceptionally long and strong. Professor Huxley gave its
+length at 29 inches. My own studies lead to the conclusion that the
+first finger bone of the wing was the shorter, and that although they
+did not differ greatly in length, the second was probably the longest,
+as in Campylognathus.
+
+Professor Huxley makes the second and third phalanges 7-3/4 inches long,
+and the first only about 3/8 inch shorter, while the fourth phalange is
+6-1/2 inches. These measurements are based upon some specimens in the
+Oxford University Museum. There is only one first phalange which has a
+length of 7-3/4 inches. The others are between 5 and 6 inches, or but
+little exceed 4 inches; so that as all the fourth phalanges which are
+known have a length of 6-1/2 inches, it is possible that the normal
+length of the first phalange in the larger species was 5-1/2 inches. The
+largest of the phalanges which may be classed as second or third is
+8-1/2 inches, and that, I suppose, may have been associated with the
+7-3/4 inches first phalange. But the other bones which could have had
+this position all measure 5-1/2 and 7-3/4 inches. The three species
+indicated by finger bones may have had the measurements:--
+
+     Phalanges of the wing finger
+   ________________/\________________
+  |                                  |
+    I.        II.      III.      IV.
+  7-3/4     8-1/2      [7?]      6-1/2        }  length of each bone
+  5-1/2     7-3/4     5-1/2     [4-1/2?]      }       in inches.
+  4-1/2     ----      ----       ----         }
+
+The femur is represented by many examples--one 3-3/4 inches long, and
+others less than 3 inches long (2-9/10). In Campylognathus, which has so
+much in common with the jaw and the wing bones in size, the upper leg
+bone is 2-8/10 inches. Therefore if we assign the larger femur to the
+larger wing, the femur will be relatively longer in all species of
+Rhamphocephalus than in Campylognathus. Only one example of a tibia is
+preserved. It is 3-1/2 inches long, or only 1/10 inch shorter than the
+bone in Campylognathus, which has the femur 2-8/10 inches, so that I
+refer the tibia of Rhamphocephalus to the species which has the
+intermediate length of wing. These coincidences with Campylognathus
+establish a close affinity, and may raise the question whether the Upper
+Lias species may not be included in the Stonesfield Slate genus
+Rhamphocephalus.
+
+The late Professor Phillips, in his _Geology of Oxford_, attempted a
+restoration of the Stonesfield Ornithosaur, and produced a picturesque
+effect (p. 164); but no restoration is possible without such attention
+to the proportions of the bones as we have indicated.
+
+
+OXFORD CLAY
+
+A few bones of flying reptiles have been found in the Lower Oxford Clay
+near Peterborough, and others in the Upper Oxford Clay at St. Ives, in
+Huntingdonshire. A single tail vertebra from the Middle Oxford Clay,
+near Oxford, long since came under my own notice, and shows that these
+animals belong to a long-tailed type like Campylognathus. The cervical
+vertebrae are remarkable for being scarcely longer than the dorsal
+vertebrae; and the dorsal are at least half as long again as is usual,
+having rather the proportion of bones in the back of a crocodile.
+
+
+LITHOGRAPHIC SLATE
+
+Long-tailed Pterodactyles are beautifully preserved in the Lithographic
+Limestone of the south of Bavaria, at Solenhofen, and the quarries in
+its neighbourhood, often with the skeleton or a large part of it
+flattened out in the plane of bedding of the rock. Fine skeletons are
+preserved in the superb museum at Munich, at Heidelberg, Bonn, Haarlem,
+and London, and are all referred to the genus Rhamphorhynchus or to
+Scaphognathus. It is a type with powerfully developed wings and a long,
+stiff tail, very similar to that of Dimorphodon, so that some
+naturalists refer both to the same family. There is some resemblance.
+
+The type which is most like Dimorphodon is the celebrated fossil at
+Bonn, sometimes called _Pterodactylus crassirostris_, which in a
+restored form, with a short tail, has been reproduced in many
+text-books. No tail is preserved in the slab, and I ventured to give the
+animal a tail for the first time in a restoration (p. 163) published by
+the _Illustrated London News_ in 1875, which accompanied a report of a
+Royal Institution lecture. Afterwards, in 1882, Professor Zittel, of
+Munich, published the same conclusion. The reason for restoring the tail
+was that the animal had the head constructed in the same way as
+Pterodactyles with a long tail, and showed differences from types in
+which the tail is short; and there is no known short-tailed
+Pterodactyle, with wrist and hand bones, such as characterise this
+animal. The side of the face has a general resemblance to the
+Pterodactyles from the Lias, for although the framework is firmer, the
+four apertures in the head are similarly placed. The nostril is rather
+small and elongated, and ascends over the larger antorbital vacuity. The
+orbit for the eye is the largest opening in the head, so that these
+three apertures successively increase in size, and are followed by the
+vertically elongated post-orbital vacuity. The teeth are widely spaced
+apart, and those in the skull extend some distance backward to the end
+of the maxillary bone. There are few teeth in the lower jaw, and they
+correspond to the large anterior teeth of Dimorphodon, there being no
+teeth behind the nasal opening. The lower jaw is straight, and the
+extremities of the jaws met when the mouth was closed. The breast bone
+does not show the keel which is so remarkable in Rhamphorhynchus, which
+may be attributed to its under side being exposed, so as to exhibit the
+pneumatic foramina.
+
+The ribs have double heads, more like those of a Crocodile in the region
+of the back than is the case with the bird-like ribs from Stonesfield.
+The second joint in the wing finger may be longer than the first--a
+character which would tend to the association of this Pterodactyle with
+species from the Lias; a relation to which attention was first drawn by
+Mr. E. T. Newton, who described the Whitby skull.
+
+The Pterodactyles from the Solenhofen Slate which possess long tails
+have a series of characters which show affinity with the other
+long-tailed types. The jaws are much more slender. The orbit of the eye
+in Rhamphorhynchus is enormously large, and placed vertically above the
+articulation for the lower jaw. Immediately in front of the eye are two
+small and elongated openings, the hinder of which, known as the
+antorbital vacuity, is often slightly smaller than the nostril, which is
+placed in the middle length of the head, or a little further back,
+giving a long dagger-shaped jaw, which terminates in a toothless spear.
+The lower jaw has a corresponding sharp extremity. The teeth are
+directed forward in a way that is quite exceptional. Notwithstanding the
+massiveness and elongation of the neck vertebrae, which are nearly twice
+as long as those of the back, the neck is sometimes only about half the
+length of the skull.
+
+All these long-tailed species from the Lithographic Stone agree in
+having the sternum broad, with a long strong keel, extending far
+forward. The coracoid bones extend outward like those of a Crocodile, so
+as to widen the chest cavity instead of being carried forward as the
+bones are in Birds. These bones in this animal were attached to the
+anterior extremity of the sternum, so that the keel extended in advance
+of the articulation as in other Pterodactyles. The breadth of the
+sternum shows that, as in Mammals, the fore part of the body must have
+been fully twice the width of the region of the hip-girdle, where the
+slenderer hind limbs were attached. The length of the fore limb was
+enormous, for although the head suggests an immense length relatively
+to the body, nearly equal to neck and back together, the head is not
+more than a third of the length of the wing bones. The wing bones are
+remarkable for the short powerful humerus with an expanded radial crest,
+which is fully equal in width to half the length of the bone. Another
+character is the extreme shortness of the metacarpus, usually associated
+with immense strength of the wing metacarpal bone.
+
+The hind limbs are relatively small and relatively short. The femur is
+usually shorter than the humerus, and the tibia is much shorter than the
+ulna. The bones of the instep, instead of being held together firmly as
+in the Lias genera, diverge from each other, widening out, though it
+often happens that four of the five metatarsals differ but little in
+length. The fifth digit is always shorter.
+
+The hip-girdle of bones differs chiefly from other types in the way in
+which those bones, which have sometimes been likened to the marsupial
+bones, are conditioned. They may be a pair of triangular bones which
+meet in the middle line, so that there is an outer angle like the arm of
+a capital Y. Sometimes these triangular bones are blended into a curved,
+bow-shaped arch, which in several specimens appears to extend forward
+from near the place of articulation of the femur. This is seen in fossil
+skeletons at Heidelberg and Munich. It is possible that this position is
+an accident of preservation, and that the prepubic bones are really
+attached to the lower border of the pubic bones.
+
+Immense as the length of the tail appears to be, exceeding the skull and
+remainder of the vertebral column, it falls far short of the combined
+length of the phalanges of the wing finger. The power of flight was
+manifestly greater in Rhamphorhynchus than in other members of the
+group, and all the modifications of the skeleton tend towards adaptation
+of the animals for flying. The most remarkable modification of structure
+at the extremity of the tail was made known by Professor Marsh in a
+vertical, leaf-like expansion in this genus, which had not previously
+been observed (p. 161). The vertebrae go on steadily diminishing in
+length in the usual way, and then the ossified structures which bordered
+the tail bones and run parallel with the vertebrae in all the
+Rhamphorhynchus family, suddenly diverge downward and upward at right
+angles to the vertebrae, forming a vertical crest above and a
+corresponding keel below; and between these structures, which are
+identified with the neural spines and chevron bones of ordinary
+vertebrae, the membrane extends, giving the extremity of the tail a
+rudder-like feature, which, from knowledge of the construction of the
+tail of a child's kite, may well be thought to have had influence in
+directing and steadying the animal's movements. There are many minor
+features in the shoulder-girdle, which show that the coracoid, for
+example, was becoming unlike that bone in the Lias, though it still
+continues to have a bony union with the elongated shoulder-blade of the
+back.
+
+  [Illustration: FIG. 56.  RESTORATION OF THE SKELETON OF
+  _RHAMPHORHYNCHUS PHYLLURUS_
+
+  From the Solenhofen Slate, partly based upon the skeleton
+  with the wing membranes preserved]
+
+  [Illustration: FIG. 57.  RESTORATION OF THE SKELETON OF _SCAPHOGNATHUS
+  CRASSIROSTRIS_
+
+  Published in the _Illustrated London News_ in 1875. In which a tail is
+  shown on the evidence of the structure of the head and hand]
+
+  [Illustration: FIG. 58.  SIX RESTORATIONS
+
+    1. Ramphocephalus. Stonesfield Slate. John Phillips, 1871
+    2. Rhamphorhynchus. O. C. Marsh, 1882
+    3. Rhamphorhynchus. V. Zittel, 1882
+    4. Ornithostoma. Williston, 1897
+    5. Dimorphodon. Buckland, 1836. Tail then unknown
+    6. Ornithocheirus. H. G. Seeley, 1865]
+
+The great German delineator of these animals, Von Meyer, admitted six
+different species. Mr. Newton and Mr. Lydekker diminish the number to
+four. It is not easy to determine these differences, or to say how far
+the differences observed in the bones characterise species or genera. It
+is certain that there is one remarkable difference from other and older
+Pterodactyles, in that the last or fourth bone in the wing finger is
+usually slightly longer than the third bone, which precedes it. There is
+a certain variability in the specimens which makes discussion of their
+characters difficult, and has led to some forms being regarded as
+varieties, while others, of which less material is available, are
+classed as species. I am disposed to say that some of the confusion may
+have resulted from specimens being wrongly named. Thus, there is a
+Rhamphorhynchus called curtimanus, or the form with the short hand. It
+is represented by two types. One of these appears to have the humerus
+short, the ulna and radius long, and the finger bones long; the other
+has the humerus longer, the ulna much shorter, and the finger bones
+shorter. They are clearly different species, but the second variety
+agrees in almost every detail with a species named hirundinaceus, the
+swallow-like Rhamphorhynchus. This identification shows, not that the
+latter is a bad species, but that curtimanus is a distinct species which
+had sometimes been confounded with the other. While most of these
+specimens show a small but steady decrease in the length of the several
+wing finger bones, the species called Gemmingi has the first three bones
+absolutely equal and shorter than in the species curtimanus, longimanus,
+or hirundinaceus. In the same way, on the evidence of facts, I find
+myself unable to join in discarding Professor Marsh's species phyllurus,
+on account of the different proportions of its limb bones. The humerus,
+metacarpus, and third phalange of the wing finger in _Rhamphorhynchus
+phyllurus_ are exceptionally short as compared with other species.
+Everyone agrees that the species called longicaudus is a distinct one,
+so that it is chiefly in slight differences in the proportions of
+constituent parts of the skeleton that the types of the Rhamphorhynchus
+are distinguished from each other. I cannot quite concur with either
+Professor Zittel (Fig. 58, 3) or Professor Marsh (Fig. 58, 2) in the
+expansion which they give to the wing membrane in their restorations;
+for although Professor Zittel represents the tail as free from the hind
+legs, while Professor Marsh connects them together, they both concur in
+carrying the wing membrane from the tip of the wing finger down to the
+extremity of the ankle joint. I should have preferred to carry it no
+further down the body than the lower part of the back, there being no
+fossil evidence in favour of this extension so far as specimens have
+been described. Neither the membranous wings figured by Zittel nor by
+Marsh would warrant so much body membrane as the Rhamphorhynchus has
+been credited with. I have based my restoration (p. 161) of the skeleton
+chiefly on _Rhamphorhynchus phyllurus._
+
+
+THE SHORT-TAILED TYPES
+
+The Pterodactylia are less variable; and the variation among the species
+is chiefly confined to relative length of the head, length of the neck,
+and the height of the body above the ground. The tail is always so short
+as to be inappreciable. Many of the specimens are fragmentary, and the
+characters of the group are not easily determined without careful
+comparisons and measurements. The bones of the fore limb and wing
+finger are less stout than in the Rhamphorhynchus type, while the femur
+is generally a little longer than the humerus, and the wing finger is
+short in comparison with its condition in Rhamphorhynchus. These
+short-tailed Pterodactyles give the impression of being active little
+animals, having very much the aspect of birds, upon four legs or two.
+The neck is about as long as the lower jaw, the antorbital vacuity in
+the head is imperfectly separated from the much larger nasal opening,
+the orbit of the eye is large and far back, the teeth are entirely in
+front of the nasal aperture, and the post-orbital vacuity is minute and
+inconspicuous. The sternum is much wider than long, and no specimens
+give evidence of a manubrium. The finger bones progressively decrease in
+length. The prepubic bones have a partially expanded fan-like form, and
+never show the triradiate shape, and are never anchylosed. About fifteen
+different kinds of Pterodactyles have been described from the Solenhofen
+Slate, mostly referred to the genus Pterodactylus, which comprises forms
+with a large head and long snout. Some have been placed in a genus
+(Ornithocephalus, or Ptenodracon) in which the head is relatively short.
+The majority of the species are relatively small. The skull in
+_Ornithocephalus brevirostris_ is only 1 inch long, and the animal could
+not have stood more than 1-1/2 inches to its back standing on all fours,
+and but little over 2-1/2 inches standing as a biped, on the hind limbs.
+
+A restoration of the species called _Pterodactylus scolopaciceps_,
+published in 1875 in the _Illustrated London News_ in the position of a
+quadruped, shows an animal a little larger, with a body 2-1/2 inches
+high and 6 to 7 inches long, with the wing finger 4-1/2 inches long.
+Larger animals occur in the same deposit, and in one named
+_Pterodactylus grandis_ the leg bones are a foot long; and such an
+animal may have been nearly a foot in height to its back, standing as a
+quadruped, though most of these animals had the neck flexible and
+capable of being raised like the neck of a Goose or a Deer (p. 30), and
+bent down like a Duck's when feeding.
+
+  [Illustration: FIG. 59.  RESTORATION OF THE SKELETON OF _PTENODRACON
+  BREVIROSTRIS_
+
+  From the Solenhofen Slate. The fourth joint of the wing finger appears
+  to be lost and has not been restored in the figure. (Natural size)]
+
+The type of the genus Pterodactylus is the form originally described by
+Cuvier as_ Pterodactylus longirostris_ (p. 28). It is also known as _P.
+antiquus_, that name having been given by a German naturalist after
+Cuvier had invented the genus, and before he had named the species.
+There are some remarkable features in which Cuvier's animal is distinct
+from others which have been referred to the same genus. Thus the head is
+4-1/2 inches long, while the entire length of the backbone to the
+extremity of the tail is only 6-1/2 inches, and one vertebra in the neck
+is at least as long as six in the back, so that the animal has the
+greater part of its length in the head and neck, although the neck
+includes so few vertebrae. Nearly all the teeth--which are few in number,
+short and broad, not exceeding a dozen in either jaw--are limited to the
+front part of the beak, and do not extend anywhere near the nasal
+vacuity. This is not the case with all.
+
+In the species named _P. Kochi_, which I have regarded as the type of a
+distinct genus, there are large teeth in the front of the jaw
+corresponding to those of Pterodactylus, and behind these a smaller
+series of teeth extending back under the nostril, which approaches close
+to the orbit of the eye, without any indication of a separate antorbital
+vacuity. On those characters the genus Diopecephalus was defined. It is
+closely allied to Pterodactylus; both agree in having the ilium
+prolonged forward more than twice as far as it is carried backward, the
+anterior process covering about half a dozen vertebrae, as in
+_Pterodactylus longirostris_. A great many different types have been
+referred to _Pterodactylus Kochi_, and it is probable that they may
+eventually be distinguished from each other. The species in which the
+upper borders of the orbits approximate could be separated from those in
+which the frontal interspace is wider.
+
+  [Illustration: FIG. 60.  CYCNORHAMPHUS SUEVICUS FROM THE SOLENHOFEN
+  SLATE SHOWING THE SCATTERED POSITION OF THE BONES
+
+  _Original in the Museum at Tuebingen_]
+
+  [Illustration: FIG. 61.  CYCNORHAMPHUS SUEVICUS
+  RESTORATION SHOWING THE FORM OF THE BODY AND THE WING MEMBRANES]
+
+It is a remarkable feature in these animals that the middle bones of the
+foot, termed instep bones or metatarsals, are usually close together, so
+that the toes diverge from a narrow breadth, as in _P. longirostris_,
+_P. Kochi_, and other forms; but there also appear to be splay-footed
+groups of Pterodactyles like the species which have been named _P.
+elegans_ and _P. micronyx_, in which the metatarsus widens out so that
+the bones of the toes do not diverge, and that condition characterises
+the Ptenodracon (_Pterodactylus brevirostris_), to which genus these
+species may possibly be referred. Nearly all who have studied these
+animals regard the singularly short-nosed species _P. brevirostris_ as
+forming a separate genus. For that genus Soemmerring's descriptive name
+Ornithocephalus, which he used for Pterodactyles generally, might
+perhaps have been retained. But the name Ptenodracon, suggested by Mr.
+Lydekker, has been used for these types.
+
+  [Illustration: FIG. 62.  _CYCNORHAMPHUS SUEVICUS_
+
+  Skeleton restored from the bones in Fig. 60]
+
+  [Illustration: FIG. 63.  RESTORATION OF SKELETON CYCNORHAMPHUS FRAASI
+  SHOWING THE LIMBS ON THE RIGHT SIDE
+
+  _From a specimen in the Museum at Stuttgart_]
+
+  [Illustration: FIG. 64.  CYCNORHAMPHUS FRAASI
+  RESTORATION OF THE FORM OF THE BODY]
+
+Some of the largest specimens preserved at Stuttgart and Tuebingen have
+been named _Pterodactylus suevicus_ and _P. Fraasii_. They do not
+approach the species _P. grandis_ in size, so far as can be judged from
+the fragmentary remains figured by Von Meyer; for what appears to be the
+third phalange of the wing finger is 7-1/2 inches long, while in these
+species it is less than half that length, indicating an enormous
+development of wing, relatively to the length of the hind limb, which
+would probably refer the species to another genus. _Pterodactylus
+suevicus_ differs from the typical Pterodactyles in having a rounded,
+flattened under surface to the lower jaw, instead of the common
+condition of a sharp keel in the region of the symphysis. The beak also
+seems flattened and swan-like, and the teeth are limited to the front of
+the jaw. There appear to be some indications of small nostrils, which
+look upward like the nostrils of Rhamphorhynchus, but this may be a
+deceptive appearance, and the nostrils are large lateral vacuities,
+which are in the position of antorbital vacuities, so that there would
+appear to be only two vacuities in the side of the head in these
+animals. The distinctive character of the skeleton in this genus is
+found in the extraordinary length of the metacarpus and in the complete
+ossification of the smaller metacarpal bones throughout their length.
+The metacarpal bones are much longer than the bones of the fore-arm, and
+about twice the length of the humerus. The first wing phalange is much
+longer than the others, which successively and rapidly diminish in
+length, so that the third is half the length of the first. There are
+differences in the pelvis; for the anterior process of the ilium is very
+short, in comparison with its length in the genus Pterodactylus. And the
+long stalk of the prepubic bone with its great hammer-headed expansion
+transversely in front gives those bones a character unlike other genera,
+so that Cycnorhamphus ranks as a good genus, easily distinguished from
+Cuvier's type, in which the four bones of the wing are more equal in
+length, and the last is more than half the length of the first; while
+the metacarpus in that genus is only a little longer than the humerus,
+and much shorter than the ulna. The _Pterodactylus suevicus_ has the
+neck vertebrae flat on the under side, and relatively short as compared
+with the more slender and narrower vertebrae of _P. Fraasii_.
+
+
+
+
+CHAPTER XV
+
+ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS
+
+
+When staying at Swanage, in Dorsetshire, many years ago, I had the rare
+good fortune to obtain from the Purbeck Beds the jaw of a Pterodactyle,
+which had much in common in plan with the _Cycnorhamphus Fraasii_ from
+the Lithographic Slate, which is preserved at Stuttgart. The
+tooth-bearing part of this lower jaw is 8 inches long as preserved,
+extending back 3 inches beyond the symphysis portion in which the two
+sides are blended together. It is different from Professor Fraas's
+specimen in having the teeth carried much further back, and in the
+animal being nearly twice as large. This fragment of the jaw is little
+more than 1 foot long, which is probably less than half its original
+length. A vertebra nearly 5 inches long, which is more than twice the
+length of the longest neck bones in the Stuttgart fossil, is the only
+indication of the vertebral column. Professor Owen described a wing
+finger bone from these Purbeck Beds, which is nearly 1 foot long. He
+terms it the second of the finger. It may be the third, and on the
+hypothesis that the animal had the proportions of the Solenhofen fossil
+just referred to, the first wing finger bone of the English Purbeck
+Pterodactyle would have exceeded 2 feet in length, and would give a
+length for the wing finger of about 5 feet 3 inches. For this animal the
+name Doratorhynchus was suggested, but at present I am unable to
+distinguish it satisfactorily from Cycnorhamphus, which it resembles in
+the forms both of the neck bones and of the jaw. Very small
+Pterodactyles are also found in the English Purbeck strata, but the
+remains are few, and scattered, like these larger bones.
+
+  [Illustration: FIG. 65.  THE LONGEST KNOWN NECK VERTEBRA
+
+  From the Purbeck Beds of Swanage. (Half natural size)]
+
+
+ORNITHODESMUS LATIDENS
+
+  [Illustration: FIG. 66.  CERVICAL VERTEBRA OF ORNITHODESMUS
+
+  From the Wealden Beds of the Isle of Wight]
+
+The Wealden strata being shallow, fresh-water deposits might have been
+expected to supply better knowledge of Pterodactyles than has hitherto
+been available. Jaws of Ornithocheirus sagittirostris have been found
+in the beds at Hastings, and in other parts of Sussex. Some fragments
+are as large as anything known. The best-preserved remains have come
+from the Isle of Wight, and were rewards to the enthusiastic search of
+the Rev. W. Fox, of Brixton. In the principal specimen the teeth were
+short and wide, the head large and deep with large vacuities, but the
+small brain case of that skull is bird-like. The neck bones are 2-1/2
+inches long. In the upper part of the back the bones are united together
+by anchylosis, so that they form a structure in the back like a sacrum,
+which does not give attachment to the scapula, as in some Pterodactyles
+from the Chalk, but the bones are simply blended, as in the
+frigate-bird, allied to Pelicans and Cormorants. And then after a few
+free vertebrae in the lower part of the back, succeeds the long sacrum,
+formed in the usual way, of many vertebrae. I described a sacrum of this
+type from the Wealden Beds, under the name _Ornithodesmus_, referable to
+another species, which in many respects was so like the sacrum of a Bird
+that I could not at the time separate it from the bird type. This genus
+has a sternum with a strong deep keel, and the articulation for the
+coracoid bones placed at the back of the keel in the usual way, but with
+a relation to each other seen in no genus hitherto known, for the
+articular surfaces are wedge-shaped instead of being ovate; and instead
+of being side by side, they obliquely overlap, practically as in wading
+birds like the Heron. I have never seen any Pterodactyle teeth so
+flattened and shaped like the end of a lancet; and from this character
+the form was known between Mr. Fox and his friends as "latidens." The
+name Ornithodesmus is as descriptive of the sternum as of the vertebral
+column. The wing bones, as far as they are preserved, have the
+relatively great strength in the fore limb which is found in many of the
+Pterodactyles of the Cretaceous period, and are quite as large as the
+largest from the Cambridge Greensand. In the Sussex species named _P.
+sagittirostris_ the lower jaw articulation was inches wide.
+
+
+  [Illustration: FIG. 67.  STERNUM OF _ORNITHODESMUS_
+
+  Showing the overlapping facets for the coracoid bones (shaded) behind
+  the median keel]
+
+  [Illustration: FIG. 68.  FRONT OF THE KEEL OF THE STERNUM OF
+  _ORNITHODESMUS LATIDENS_
+
+  Showing also the articulation for the coracoid bone]
+
+A few Pterodactyles' bones have been discovered in the Neocomian sands
+of England and Germany, and other larger bones occur in the Gault of
+Folkestone and the north of France; but never in such association as to
+throw light on the aspect of the skeleton.
+
+
+ORNITHOCHEIRUS
+
+Within my own memory Pterodactyle remains were equally rare from the
+Cambridge Greensand. The late Professor Owen in one of his public
+lectures produced the first few fragments received from Cambridge, and
+with a knowledge which in its scientific method seemed to border on the
+power of creation, produced again the missing parts, so that the bones
+told their story, which the work of waves and mineral changes in the
+rock had partly obliterated. Subsequently good fortune gave me the
+opportunity during ten years to help my University in the acquisition
+and arrangement of the finest collection of remains of these animals in
+Europe. Out of an area of a few acres, during a year or two, came the
+thousand bones of Ornithosaurs, mostly associated sets of remains, each
+a part of a separate skeleton, described in my published catalogues, as
+well as the best of those at York and in the British Museum and other
+collections in London.
+
+The deposit which yields them, named Cambridge Greensand, may or may not
+represent a long period of time in its single foot of thickness; but the
+abundance of fossils, obtained whenever the workmen were adequately
+remunerated for preserving them, would suggest that the Pterodactyles
+might have lived like sea-birds or in colonies like the Penguins, if it
+were not that the number of examples of each species found is always
+small, and the many variations of structure suggested rather that the
+individuals represent the life of many lands. The collections of remains
+are mostly from villages in the immediate vicinity of Cambridge, such as
+Chesterton, Huntingdon Road, Coldham Common, Haslingfield, Barton,
+Shillington, Ditton, Granchester, Harston, Barrington, stretching south
+to Ashwell in Bedfordshire on the one hand, as well as further north by
+Horningsea into the fens. Each appears to be the associated bones of a
+single individual. The remains mostly belong to comparatively large
+animals. Some were small, though none have been found so diminutive as
+the smallest from the Solenhofen Slate. The largest specimens with long
+jaws appear to have had the head measuring not more than eighteen inches
+in length, which is less than half the size of the great toothless
+Pterodactyles from Kansas.
+
+  [Illustration: FIG. 69.  RESTORATION OF THE SKULL OF ORNITHOCHEIRUS
+
+  The parts left white are in the Geological Museum at Cambridge. The
+  shaded parts have not been found. The two holes are the eye and the
+  nostril (From the Cambridge Greensand)]
+
+The Cambridge specimens manifestly belong to at least three genera.
+Something may be said of the characters of the large animals which are
+included in the genus Ornithocheirus. These fossils have many points of
+structure in common with the great American toothless forms which are of
+similar geological age. The skull is remarkable for having the back of
+the head prolonged in a compressed median crest, which rose above the
+brain case, and extended upward and over the neck vertebrae, so as to
+indicate a muscular power not otherwise shown in the group. For about
+three inches behind the brain this wedge of bone rested on the vertebrae,
+and probably overlapped the first three neural arches in the neck.
+
+Another feature of some interest is the expansion of the bone which
+comes below the eye. In Birds this malar or cheek bone is a slender rod,
+but in these Pterodactyles it is a vertical plate, which is blended with
+the bone named the quadrate bone, which makes the articulation with the
+lower jaw in all oviparous animals.
+
+The beak varies greatly in length and in form, though it is never quite
+so pointed as in the American genus, for there is always a little
+truncation in front, when teeth are seen projecting forward from a
+position somewhat above the palate; the snout is often massive and
+sometimes club-shaped. Except for these variations of shape in the
+compressed snout, which is characterised by a ridge in the middle of the
+palate, and a corresponding groove in the lower jaw, and the teeth,
+there is little to distinguish what is known of the skull in its largest
+English Greensand fossils from the skull remains which abound in the
+Chalk of Kansas.
+
+This English genus Ornithocheirus, represented by a great number of
+species, had the neural arch of the neck bones expanded transversely
+over the body of the vertebra in a way that characterises many birds
+with powerful necks, and is seen in a few Pterodactyles from Solenhofen.
+
+It is difficult to resist the conclusion that the neck vertebrae were
+not usually more than twice to three times as long as those of the back,
+and it would appear that the caudal vertebrae in the English Cretaceous
+types were comparatively large, and about twice as long as the dorsal
+vertebrae. Unless there has been a singular succession of accidents in
+the association of these vertebrae with the other remains, Ornithocheirus
+had a tail of moderate length, formed of a few vertebrae as long as those
+of the neck, though more slender, quite unlike the tail in either the
+long-tailed or short-tailed groups of Solenhofen Pterodactyles, and
+longer than in the toothless Pterodactyles of America.
+
+  [Illustration: FIG. 70.  CERVICAL VERTEBRA, ORNITHOCHEIRUS
+
+  Under side, half natural size. (Cambridge Greensand)]
+
+The singular articulation for the humerus at the truncated extremity of
+the coracoid bone is a character of this group, as is the articulation
+of the scapulae with the neural arches of the dorsal vertebrae, at right
+angles to them (p. 115), instead of running over the ribs as in Birds
+and as in other Pterodactyles.
+
+The smaller Pterodactyles have their jaws less compressed from side to
+side. The upper arm bone, the humerus, instead of being truncated at its
+lower end as in Ornithocheirus, is divided into two or three rounded
+articular surfaces. That for the radius, the bone which carries the
+wrist, is a distinct and oblique rounded facet, while the ulna has a
+rounded and pulley-like articulation on which the hand may rotate. These
+differences are probably associated with an absence of the remarkable
+mode of union of the scapulae with the dorsal vertebrae. But I have
+hesitated to give different names to these smaller genera because no
+example of scapula has come under my notice which is not truncated at
+the free end. I do not think this European type can be the Nyctodactylus
+of Professor Marsh, in which sutures appear to be persistent between the
+bodies of the vertebrae and their arches, because no examples have been
+found at Cambridge with the neural arches separated, although the
+scapula is frequently separated from the coracoid in large animals.
+
+  [Illustration: FIG. 71.  UPPER AND LOWER JAWS OF AN ENGLISH
+  PTERODACTYLE FROM THE CHALK, AS PRESERVED]
+
+
+ORNITHOSTOMA
+
+  [Illustration: FIG. 72.  THE PALATE OF THE ENGLISH TOOTHLESS
+  PTERODACTYLE, ORNITHOSTOMA]
+
+  [Illustration: FIG. 73.  TYPES OF THE AMERICAN TOOTHLESS PTERODACTYLE,
+  ORNITHOSTOMA
+
+  Named by Marsh, Pteranodon]
+
+The most interesting of all the English Pterodactyle remains is the
+small fragment of jaw figured by Sir Richard Owen in 1859, which is a
+little more than two inches long and an inch wide, distinguished by a
+concave palate with smooth rounded margins to the jaws and a rounded
+ridge to the beak. It is the only satisfactory fragment of the animal
+which has been figured, and indicates a genus of toothless
+Pterodactyles, for which the name Ornithostoma was first used in 1871.
+After some years Professor Marsh found toothless Pterodactyles in
+Kansas, and indicated several species. There are remains to the number
+of six hundred specimens of these American animals in the Yale Museum
+alone; but very little was known of them till Professor Williston, of
+Lawrence, in Kansas, described the specimens from the Kansas University
+Museum, when it became evident that the bones of the skeleton are mostly
+formed on the same plan as those of the Cambridge Greensand genus,
+Ornithocheirus. They are not quite identical. Professor Williston adopts
+for them the name Ornithostoma, in preference to Pteranodon which Marsh
+had suggested. Both animals have the dagger-shaped form of jaw, with
+corresponding height and breadth of the palate. The same flattened sides
+to the snout, converging upwards to a rounded ridge, the same compressed
+rounded margin to the jaw, which represents the border in which teeth
+are usually implanted, and in both the palate has the same smooth
+character forming a single wide concave channel. Years previously I had
+the pleasure of showing to Professor Marsh the remarkable characters of
+the jaw, shoulder-girdle bones, and scapulae in the Greensand
+Pterodactyles while the American fossils were still undiscovered. I
+subsequently made the restoration of the shoulder-girdle (p. 115).
+Professor Williston states to me that the shoulder-girdle bones in
+American examples of Ornithostoma have a close resemblance to those of
+Ornithocheirus figured in 1891, as is evident from remains now shown in
+the British Museum. It appears that the Kansas bones are almost
+invariably crushed flat, so that their articular ends are distorted. The
+neck vertebrae are relatively stout as in Ornithocheirus. The hip-girdle
+of the American Ornithostoma can be closely paralleled in some English
+specimens of Ornithocheirus, though each prepubic bone is triangular in
+the American fossils as in _P. rhamphastinus_. They are united into a
+transverse bar as in Rhamphorhynchus, unknown in the English fossils.
+The femur has the same shape as in Ornithocheirus; and the long tibia
+terminates in a pulley. There is no fibula. The sternum in both has a
+manubrium, or thick keel mass, prolonged in front of its articular
+facets for the coracoid bones, which are well separated from each other.
+Four ribs articulate with its straight sides. The animal has four toes
+and the fifth is rudimentary; there are no claws to the first and
+second.
+
+  [Illustration: FIG. 74.  RESTORATION OF THE SKELETON OF _ORNITHOSTOMA
+  INGENS_ (MARSH)
+
+  From the Niobrara Cretaceous of Western Kansas. Made by Professor
+  Williston. The original has a spread of wing of about 19 feet 4
+  inches. Fragments of larger individuals are preserved at Munich]
+
+In the restoration which Professor Williston has made the wing
+metacarpal is long, and in the shortest specimen measures 1 foot 7
+inches, and in the longest 1 foot 8 inches. This is exactly equal to the
+length of the first phalange of the wing finger. The second wing finger
+bone is 3 inches shorter, the third is little more than half the length
+of the first, while the fourth is only 6-3/4 inches long, showing a
+rapid shortening of the bones, a condition which may have characterised
+all the Cretaceous Pterodactyles. The short humerus, about 1 foot long,
+and the fore-arm, which is scarcely longer, are also characteristic
+proportions of Ornithostoma or Pteranodon, as known from the American
+specimens. Professor Williston gives no details of the remarkable tail,
+beyond saying that the tail is small and short, and that the vertebrae
+are flat at the ends, without transverse processes. In the restoration
+the tail is shorter than in the short-tailed species from the
+Lithographic Slate, and unlike the tail in Ornithocheirus.
+
+
+This is the succession of Pterodactyles in geological time. Their
+history is like that of the human race. In the most ancient nations
+man's life comes upon us already fully organised. The Pterodactyles
+begin, so far as isolated bones are concerned, in the Rhaetic strata;
+perhaps in the Muschelkalk or middle division of the Trias. And from the
+beginning of the Secondary time they live on with but little diversity
+in important and characteristic structures, and so far as habit goes,
+the great Pterodactyles of the Upper Chalk of England cannot be said to
+be more highly organised than the earlier stiff-tailed genera of the
+Lias or the Oolites. There is nothing like evolution. No modification
+such as that which derives the one-toed horse or the two-toed ox from
+ancestors with a larger number of digits. On the other hand, there is
+little, if any, evidence of degeneration. The later Pterodactyles do not
+appear to have lost much, although the tail in some of the Solenhofen
+genera may be degenerate when compared with the long tail of
+Dimorphodon; but the short-tailed types are found side by side with the
+long-tailed Rhamphorhynchus. The absence of teeth may be regarded as
+degeneration, for they have presumably become lost, in the same way that
+Birds now existing have lost the teeth which characterised the fossil
+birds--Ichthyornis of the American Greensand, and Archaeopteryx of the
+Upper Oolites of Bavaria. But just as some of the earlier Pterodactyles
+have no teeth at the extremity of the jaw, such as Dorygnathus and
+Rhamphorhynchus, so the loss of teeth may have extended backward till
+the jaws became toothless. The specimens hitherto known give no evidence
+of such a change being in progress. But just as the division of Mammals
+termed Edentata usually wants only the teeth which characterise the
+front of the jaw, yet others, like the Great Ant-eater of South America
+named Myrmecophaga, have the jaws as free from teeth as the toothless
+Pterodactyles or living Birds, and show that in that order the teeth
+have no value in separating these animals into subordinate groups any
+more than they have among the Monotremata, where one type has teeth and
+the other is toothless.
+
+The following table gives a summary of the Geological History and
+succession in the Secondary Rocks of the principal genera of Flying
+Reptiles.
+
+  -----------------------+----------------------------------------------
+                         |             NAMES OF THE GENERA.
+  GEOLOGICAL FORMATIONS. +-----------------------+----------------------
+                         | British and European. | North American.
+  -----------------------+-----------------------+----------------------
+  Upper Chalk            |                       |} Ornithostoma
+                         |                       |}     (_Pteranodon_)
+  Lower Chalk            |} Ornithocheirus       |} Nyctodactylus
+  Upper Greensand        |}   |  Ornithostoma    |
+  Gault                  |    |                  |
+  -----------------------+    |                  |
+  Lower Greensand        |    |                  |
+  Wealden                | Ornithodesmus         |
+  Purbeck                | Doratorhynchus        |
+  -----------------------+                       |
+  Portland               |{ Pterodactylus        |
+                         |{ Ptenodracon          |
+  Kimeridge Clay and     |{ Cycnorhamphus        |
+    Solenhofen Slate     |{ Diopecephalus        |
+                         |{ Rhamphorhynchus      |
+  Coralline Oolite       |{ Scaphognathus        |
+                         |                       |
+  Oxford Clay            |                       |
+  -----------------------+                       |
+  Great Oolite and       |                       |
+    Stonesfield Slate    | Rhamphocephalus       |
+                         |                       |
+  Inferior Oolite        |                       |
+  -----------------------+                       |
+  Upper Lias             |{ Campylognathus       |
+                         |{ Dorygnathus          |
+  Lower Lias             |  Dimorphodon          |
+  -----------------------+                       |
+  Rhaetic                 |  bones                |
+                         |                       |
+  Muschelkalk            |  ? bones              |
+  -----------------------+-----------------------+----------------------
+
+
+
+
+CHAPTER XVI
+
+CLASSIFICATION OF THE ORNITHOSAURIA
+
+
+When an attempt is made to determine the place in nature of an extinct
+group of animals and the relation to each other of the different types
+included within its limits, so as to express those facts in a
+classification, attention is directed in the first place to characters
+which are constant, and persist through the whole of its constituent
+genera. We endeavour to find the structural parts of the skeleton which
+are not affected by variation in the dentition, or the proportions of
+the extremities, or length of the tail, which may define families or
+genera, or species.
+
+It has already been shown that while in many ways the Ornithosaurian
+animals are like Birds, they have also important resemblances to
+Reptiles. They are often named Pterosauria. The wing finger gives a
+distinctive character which is found in neither one class of existing
+animals nor the other, and is common to all the Pterodactyles at present
+known. They have been named Ornithosauria as a distinct minor division
+of back-boned animals, which may be regarded as neither Reptiles nor
+Birds in the sense in which those terms are used to define a Lizard or
+Ostrich among animals which still exist. It is not so much that they
+mark a transition from Reptile to Bird, as that they are a group which
+is parallel to Birds, and more manifestly holds an intermediate place
+than Birds do between Reptiles and Mammals. In plan of structure Bird
+and Reptile have more in common than was at one time suspected. The late
+Professor Huxley went so far as to generalise on those coincidences in
+parts of the skeleton, and united Birds and Reptiles into one group,
+which he named Sauropsida, to express the coincidences of structure
+between the Lizard and the Bird tribes. The idea is of more value than
+the term in which it is expressed, because Reptiles are not, as we have
+seen, a group of animals which can be defined by any set of characters
+as comprehensive as those which express the distinctive features of
+Birds. From the anatomist's point of view Birds are a smaller group, and
+while some Reptiles have affinity with them, it is rather the extinct
+than the living groups which indicate that relation. Other Reptiles have
+affinities of a more marked kind with Mammals, and there are points in
+the Ornithosaurian skeleton which are distinctly Mammalian. So that when
+the Monotreme Mammals are united with South African reptiles known as
+Theriodontia, which resemble them, in a group termed Theropsida to
+express their mammalian resemblances, it is evident that there is no one
+continuous chain of life or gradation in complexity of structure of
+animals.
+
+We have to determine whether the Ornithosauria incline towards the
+Sauropsidan or Bird-Reptile alliance, or to the Mammal-Reptile or
+Theropsidan alliance. There can be no doubt that the predominant
+tendency is to the former, with a minor affinity towards the latter.
+
+The Ornithosauria are one of a series of groups of animals, living and
+extinct, which have been combined in an alliance named the
+Ornithomorpha. That group includes at least five great divisions of
+animals, which circle about birds, known as Ornithosauria, Crocodilia,
+Saurischia, Aves, Ornithischia, and Aristosuchia. Their relations to
+each other are not evident in an enumeration, but may be shown in some
+degree in a diagram (see p. 190).
+
+
+THE ORNITHOMORPHA
+
+The Ornithomorpha arranged in this way show that the three middle
+groups--carnivorous Saurischia, Aristosuchia, herbivorous
+Ornithischia--which are usually united as Dinosauria, intervene between
+Birds and Ornithosaurs; and that the Crocodilia and Ornithosauria are
+parallel groups which are connected with Birds, by the group of
+Dinosaurs, which resembles Birds most closely.
+
+The Ornithomorpha is only one of a series of large natural groups of
+animals into which living and extinct terrestrial vertebrata may be
+arranged. And the succeeding diagram may contribute to make evident the
+relations of Ornithosauria to the other terrestrial vertebrata (see p.
+191).
+
+Herein it is seen that while the Ornithomorpha approach towards Mammalia
+through the Ornithosauria, and less distinctly through the Crocodilia,
+they approach more directly to the Sauromorpha, through the Plesiosaurs
+and Hatteria; while that group also approaches more directly to the
+Mammals through the Plesiosaurs and Anomodonts.
+
+  [Illustration: DIAGRAM OF THE AFFINITIES OF THE ORDERS OF ANIMALS
+  COMPRISED IN THE ORNITHOMORPHA.
+
+  After a diagram in the _Philosophical Transactions of the Royal
+  Society_, 1892.]
+
+The Aristosuchia is imperfectly known, and therefore to some extent a
+provisional group. It is a small group of animals.
+
+  [Illustration: DIAGRAM SHOWING THE RELATIONS OF THE ORNITHOMORPHA
+  TO THE CHIEF LARGE GROUPS OF TERRESTRIAL VERTEBRATA, AND THEIR
+  AFFINITIES WITH EACH OTHER.
+
+  After a diagram in the _Philosophical Transactions of the Royal
+  Society_, 1892.]
+
+Cordylomorpha are Ichthyosaurs and the Labyrinthodont group.
+Herpetomorpha include Lacertilia, Homoeosauria, Dolichosauria,
+Chameleonoidea, Ophidia, Pythonomorpha.
+
+The Sauromorpha comprises the groups of extinct and living Reptiles
+named Chelonia, Rhynchocephala, Sauropterygia, Anomodontia, Nothosauria,
+and Protorosauria. These details may help to explain the place which has
+been given to the Ornithosauria in the classification of animals.
+
+  [Illustration: FIG. 75.  COMPARISON OF SIX GENERA
+
+  The skulls are seen on the left side in the order of the names below
+  them]
+
+Turning to the Pterodactyles themselves, Von Meyer divided them
+naturally into short-tailed and long-tailed. The short-tailed indicated
+by the name Pterodactylus he further divided into long-nosed and
+short-nosed. The short-nosed genus has since been named Ptenodracon
+(Fig. 59, p. 167). The long-tailed group was divided into two types--the
+Rhamphorhynchus of the Solenhofen Slate (Fig. 56, p. 161) and the
+English form now known as Dimorphodon (Fig. 52, p. 150), which had been
+described from the Lias.
+
+The Cretaceous Pterodactyles form a distinct family. So that, believing
+the tail to have been short in that group (Fig. 58), there are two
+long-tailed as well as two short-tailed families, which were defined
+from their typical genera Pterodactylus, Ornithocheirus,
+Rhamphorhynchus, and Dimorphodon.
+
+The differences in structure which these animals present are, first: the
+big-headed forms from the Lias like Dimorphodon, agree with the
+Rhamphorhynchus type from Solenhofen in having a vacuity in the skull
+defined by bone, placed between the orbit of the eye and the nostril.
+With those characters are correlated the comparatively short bones which
+correspond to the back of the hand termed metacarpals, and the tail is
+long, and stiffened down its length with ossified tendons. These
+characters separate Ornithosaurs with long tails from those with short
+tails.
+
+The short-tailed types represented by Pterodactylus and Ornithocheirus
+have no distinct antorbital vacuity in the skull defined by bone. The
+metacarpal bones of the middle hand are exceptionally elongated, and the
+tail, which was flexible in both, appears to have been short. These
+differences in the skeleton warrant a primary division of flying
+reptiles into two principal groups.
+
+The short-tailed group, which was recognised by De Blainville as
+intermediate between Birds and Reptiles, may take the name
+Pterodactylia, which he suggested as a convenient, distinctive name. It
+may probably be inconvenient to enlarge its significance to comprise not
+only the true Pterodactyles originally defined as Pterosauria, but the
+newer Ornithostoma and Ornithocheirus which have been grouped as
+Ornithocheiroidea.
+
+The second order, in which the wing membrane appears to have had a much
+greater extent, in being carried down the hind limbs, where the
+outermost digit and metatarsal are modified for its support, has been
+named Pterodermata, to include the types which are arranged around
+Rhamphorhynchus and Dimorphodon.
+
+Both these principal groups admit of subdivision by many characters in
+the skeleton, the most remarkable of which is afforded by the pair of
+bones carried in front of the pubes, and termed prepubic bones. In the
+Pterodactyle family the bones in front of the pubes are always separate
+from each other, always directed forward, and have a peculiar fan-shaped
+form with concave sides like the bone which holds a similar position in
+a Crocodile. In the Ornithocheirus family the prepubic bones appear to
+have been originally triangular, but were afterwards united so as to
+form a strong continuous bar which extends transversely across the
+abdomen in advance of the pubic bones. This at least is the distinctive
+character in the genus Ornithostoma according to Professor Williston,
+which in many ways closely resembles Ornithocheirus.
+
+The two families in the long-tailed order named Pterodermata are
+separated from each other by a similar difference in their prepubic
+bones. In Dimorphodon those bones are separate from each other, and
+remain distinct through life, meeting in the middle line of the body in
+a wide plate. On the other hand, in Rhamphorhynchus the prepubic bones,
+which are at first triangular and always slender, become blended
+together into a slight transverse bar, which only differs from that
+attributed to Ornithostoma in its more slender bow-shaped form.
+
+  [Illustration: FIG. 76.  LEFT SIDE OF PELVIS OF ORNITHOSTOMA
+  (After Williston)]
+
+Thus if other characters of the skeleton are ignored and a
+classification based upon the structure of the pelvis and prepubic
+bones, there would be some ground for associating the long-tailed
+Rhamphorhynchus from the Upper Oolites which is losing the teeth in the
+front of its jaw with the Cretaceous Ornithostoma, which has the teeth
+completely wanting; while the long-tailed Dimorphodon would come into
+closer association with the short-tailed Pterodactylus. The drum-stick
+bone or tibia in Dimorphodon, with its slender fibula, like that of a
+Bird, also resembles a Bird in the rounded and pulley-shaped terminal
+end which makes the joint corresponding to the middle of the ankle bones
+in man. The same condition of a terminal pulley joint is found in the
+Cretaceous Pterodactyles. But in the true Pterodactyles and in
+Rhamphorhynchus there usually is no pulley-shaped termination to the
+lower end of the drum-stick, for the tarsal bones remain separate from
+each other, and form two rows of ossifications, showing the same
+differences as separate Dinosaurs into the divisions which have been
+referred to, from their Bird-like pelvis and tibio-tarsus, as
+Ornithischia in the one case, and Saurischia in the other from their
+bones being more like those of living Lizards.
+
+
+
+
+CHAPTER XVII
+
+FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM
+
+
+Enough has been said of the general structure of Pterodactyles and the
+chief forms which they assumed while the Secondary rocks were
+accumulating, to convey a clear idea of their relations to the types of
+vertebrate animals which still survive on the earth. We may be unable to
+explain the reasons for their existence, and for their departure from
+the plan of organisation of Reptiles and Birds. But the evidence has not
+been exhausted which may elucidate their existence. Sometimes, in
+problems of this kind, which involve comparison of the details of the
+skeleton in different animals, it is convenient to imagine the
+possibility of changes and transitions which are not yet supported by
+the discovery of fossil remains. If, for example, the Pterodactyle be
+conceived of as divested of the wing finger, which is its most
+distinctive character, or that finger is supposed to be replaced by an
+ordinary digit, like the three-clawed digits of the hand which we have
+regarded as applied to the ground, where, it may be asked, would the
+animal type be found which approximates most closely to a Pterodactyle
+which had been thus modified? There are two possible replies to such a
+question, suggested by the form of the foot. For the old Bird
+Archaeopteryx has three such clawed digits, but no wing finger. And some
+Dinosaurs also have the hand with three digits terminating in claws,
+which are quite comparable to the clawed digits of Pterodactyles.
+
+The truth expressed in the saying that no man by taking thought can add
+a cubit to his stature is of universal application in the animal world,
+in relation to the result upon the skeleton of the exercise of a
+function by the individual. Yet such is the relation in proportions of
+the different parts of the animal to the work which it performs, so
+marked is the evidence that growth has extended in direct relation to
+use of organs and active life, and that structures have become dwarfed
+from overwork, or have wasted away from disuse--seen throughout all
+vertebrate animals, that we may fairly attribute to the wing finger some
+correlated influence upon the proportions of the animal, as a
+consequence of the dependence of the entire economy upon each of its
+parts. Therefore if an allied animal did not possess a wing finger, and
+did not fly, it might not have developed the lightness of bone, or the
+length of limb which Pterodactyles possess.
+
+The mere expansion of the parachute membrane seen in so-called flying
+animals, both Mammals and Reptiles, which are devoid of wings, is
+absolutely without effect in modifying the skeleton. But when in the Bat
+a wing structure is met with which may be compared to a gigantic
+extension of the web foot of the so-called Flying Frog, the bones of the
+fingers and the back of the hand elongate and extend under the stimulus
+of the function of flight in the same way as the legs elongate in the
+more active hoofed animals, with the function of running. Therefore it
+is not improbable that the limbs shared to some extent in growth under
+stimulus of exercise which developed the wing finger. And if an animal
+can be found among fossils so far allied as to indicate a possible
+representative of the race from which these Flying Dragons arose, it
+might be expected to be at least shorter legged, and possibly more
+distinctly Reptilian in the bones of the shoulder-girdle which support
+the muscles used in flight. It may readily be understood that the kinds
+of life which were most nearly allied to Pterodactyles are likely to
+have existed upon the earth with them, and that flight was only one of
+the modes of progression which became developed in relation to their
+conditions of existence. The principal assemblage of terrestrial animals
+available for such comparison is the Dinosauria. They may differ from
+Pterodactyles as widely as the Insectivora among Mammals differ from
+Bats, but not in a more marked way. Comparisons will show that there are
+resemblances between the two extinct groups which appeal to both reason
+and imagination.
+
+Dinosaurs are conveniently divided by characters of the pelvis first
+into the order Saurischia, which includes the carnivorous Megalosaurus
+and the Cetiosaurus, with the pelvis on the Reptile plan; and secondly
+the order Ornithischia, represented by Iguanodon, with the pelvis on the
+Bird plan. It may be only a coincidence, but nevertheless an interesting
+one, that the characters of those two great groups of reptiles, which
+also extend throughout the Secondary rocks, are to some extent
+paralleled in parts of the skeleton of the two divisions of
+Pterodactyles. This may be illustrated by reference to the skull,
+pelvis, hind limb, and the pneumatic condition of the bones.
+
+  [Illustration: FIG. 77.  COMPARISON OF THE SKULL OF THE DINOSAUR
+  ANCHISAURUS WITH THE ORNITHOSAUR DIMORPHODON]
+
+The Saurischian Dinosauria have an antorbital vacuity in the side of the
+skull between the nasal opening and the eye, as in the long-tailed
+Ornithosaurs named Pterodermata. In some of the older genera of these
+carnivorous Dinosaurs of the Trias, the lateral vacuities of the head
+are as large as in Dimorphodon. But in some at least of the Iguanodont,
+or Ornithischian Dinosaurs, there is no antorbital vacuity, and the side
+of the face in that respect resembles the short-tailed Pterodactylia.
+The skull of a carnivorous Dinosaur possesses teeth which, though easily
+distinguished from those of Pterodactyles, can be best compared with
+them. The most striking difference is in the fact that in the Dinosaur
+the nostrils are nearly terminal, while in the Pterodactyle they are
+removed some distance backward. This result is brought about by growth
+taking place, in the one case at the front margin of the maxillary bone
+so as to carry the nostril forward, and in the other case at the back
+margin of the premaxillary bone. Thus an elongated part of the jaw is
+extended in front of the nostril. Hence there is a different proportion
+between the premaxillary and maxillary bones in the two groups of
+animals, which corresponds to the presence of a beak in a bird, and its
+absence in living reptiles. It is not known whether the extremity of the
+Pterodactyle's beak is a single bone, the intermaxillary bone, such as
+forms the corresponding toothless part of the jaw in the South African
+reptile Dicynodon, or whether it is made by the pair of bones called
+premaxillaries which form the extremity of the jaw in most Dinosaurs.
+Too much importance may perhaps be attached to such differences which
+are partly hypothetical, because the extinct Ichthyosaurus, which has an
+exceptionally long snout, has the two premaxillary bones elongated so as
+to extend backward to the nostrils. A similar elongation of those bones
+is seen in Porpoises, which also have a long snout; and the bones are
+carried back from the front of the head to the nostrils, which are
+sometimes known as blowholes. But the Porpoise has those premaxillary
+bones not so much in advance of the bones which carry teeth named
+maxillary, as placed in the interspace between them. The nostrils,
+however, are not limited to the extremity of the head in all Dinosaurs.
+If this region of the beak in Dimorphodon be compared with the
+corresponding part of a Dinosaur from the Permian rocks, or Trias, the
+relation of the nostril to the bones forming the beak may be better
+understood.
+
+  [Illustration: FIG. 78.  COMPARISON OF THE SKULL OF THE DINOSAUR
+  ORNITHOSUCHUS WITH THE ORNITHOSAUR DIMORPHODON]
+
+In the sandstone of Elgin, usually named Trias, a small Dinosaur is
+found, which has been named Ornithosuchus, from the resemblance of its
+head to that of a Bird. Seen from above, the head has a remarkable
+resemblance to the condition in Rhamphorhynchus, in the sharp-pointed
+beak and positions of the orbits and other openings. In side view the
+orbits have the triangular form seen in Dimorphodon, and the preorbital
+vacuities are large, as in that genus, while the lateral nostrils, which
+are smaller, are further forward in the Dinosaur. The differences from
+Dimorphodon are in the articulation for the jaw being carried a little
+backward, instead of being vertical as in the Pterodactyle, and the bone
+in front of the nose is smaller. Notwithstanding probable differences
+in the palate, the approximation, which extends to the Crocodile-like
+vacuity in the lower jaw, is such that by slight modification in the
+skull the differences would be substantially obliterated by which the
+skull of such an Ornithosaur is technically distinguished from such a
+Dinosaur.
+
+The back of the skull is clearly seen in the Whitby Pterodactyle, and
+its structure is similar to the corresponding part of such Dinosaurs as
+Anchisaurus or Atlantosaurus, without the resemblance quite amounting to
+identity, but still far closer than is the resemblance between the same
+region in the heads of Crocodiles, Lizards, Serpents, Chelonians. Few of
+these fossil Dinosaur skulls are available for comparison, and those
+differ among themselves. The coincidences rather suggest a close
+collateral relation than prove the elaboration of one type from the
+other. They may have had a common ancestor.
+
+The Trias rocks near Stuttgart have yielded Dinosaurs as unlike
+Pterodactyles as could be imagined, resembling heavily armoured
+Crocodiles, in such types as the genus Belodon. Its jaws are compressed
+from side to side, as in many Pterodactyles, and the nostrils are at
+least as far backward as in Rhamphorhynchus. Belodon has preorbital
+vacuities and postorbital vacuities, but the orbit of the eye is never
+large, as in Pterodactyles. It might not be worth while dwelling on such
+points in the skull if it were not that the pelvis in Belodon is a basin
+formed by the blending of the expanded plates of the ischium and the
+pubis, into a sheet of bone which more nearly resembles the same region
+in Pterodactyles than does the ischio-pubic region in other Dinosaurian
+animals like Cetiosaurus.
+
+The backbone in a few Dinosaurs is suggestive of Pterodactyles. In such
+genera as have been named Coelurus and Calamospondylus, in which the
+skeleton is only partially known, the neck vertebrae become elongated, so
+as to compare with the long-necked Pterodactyles. The cervical rib is
+often very similar to that type, and blended with the vertebra, as in
+Pterodactyles and Birds. The early dorsal vertebrae of Pterodactyles
+might almost be mistaken for those of Dinosaurs. The tail vertebrae of a
+Pterodactyle are usually longer than in long-tailed Dinosauria.
+
+In the limbs and the bony girdles which support them there is more
+resemblance between Pterodactyles and Dinosaurs than might have been
+anticipated, considering their manifest differences in habit. Thus all
+Dinosaurs have the hip bone named ilium prolonged in front of the
+articulation for the femur as well as behind it, almost exactly as in
+Pterodactyles and Birds (see p. 95). There is some difference in the
+pubis and ischium which is more conspicuous in form than in direction of
+the bones. There is a Pterodactyle imperfectly preserved, named
+_Pterodactylus dubius_, in which the ischium is directed backward and
+the pubis downward, and the bones unite below the acetabular cavity for
+the head of the femur to work in, but do not appear to be otherwise
+connected. In Rhamphorhynchus the connexion between these two thickened
+bars is made by a thin plate of bone. In such a Dinosaur as the American
+carnivorous Ceratosaurus the two bars of the pubis and ischium remain
+separate and diverging, and there is no film of bone extending over the
+interspace between them. The development of such a bony condition would
+make a close approximation between the Ornithosaurian pelvis and that
+of those Dinosaurs which closely resemble Pterodactyles in skull and
+teeth.
+
+  [Illustration: FIG. 79.  LEFT SIDE OF PELVIS
+  A Pterodactyle is shown between a carnivorous Dinosaur above and a
+  herbivorous Dinosaur below]
+
+Another pelvic character of some interest is the blending of the pubis
+and ischium of the right and left sides in the middle line of the body.
+There are some genera of Dinosaurs like the English Aristosuchus from
+the Weald, and the American genera Coelurus, Ceratosaurus, and others,
+in which the pubic bones, instead of uniting at their extremities, are
+pinched together from side to side, and unite down the lower part of
+their length, terminating in an expanded end like a shoe, which is seen
+to be a separate ossification, and probably formed by a pair of
+ossifications joined in the median line. This small bone, which is below
+the pubes, and in these animals becomes blended with them, we may regard
+as a pair of prepubic bones like those of Pterodactyles and Crocodiles,
+except that they have lost the stalk-like portions, which in those
+animals are developed to compensate for the diminished length of the
+pubic bones. The prepubic bones may also be developed in Iguanodon, in
+which a pair of bones of similar form remains throughout life in advance
+of the pubes, as in Pterodactyles. In those Dinosauria with the
+Bird-like type of pelvis the pubic bone is exceptionally developed,
+sending one process backward and another process forward, so that there
+is a great gap between these diverging limbs to the bone. In the region
+behind the sternum to which the ribs were attached, and in front of the
+pelvis, is a pair of bones in Iguanodon shaped like the prepubic bones
+of Dimorphodon. They have sometimes been interpreted as a hinder part of
+the sternum, but may more probably be regarded as a pair of prepubic
+bones articulating each with the anterior process of the pubis (see Fig.
+80). The small bones found at the extremities of the pubes in such
+carnivorous Dinosaurs as Aristosuchus are blended by bony union with the
+pubes. The bones in Iguanodon are placed behind the sternal region
+without any attachment for sternal ribs, and the expanded processes
+converge forwards from the stalk and unite exactly like the prepubic
+bones of Ornithosaurs. While this character, on the one hand, may link
+Pterodactyles with the Dinosaurs, on the other hand it may be a link
+between both those groups and the Crocodiles, in which the front pair of
+bones of the pelvis has also appeared to be representative of the
+prepubic bones of Flying Reptiles (see Fig. 32, p. 98).
+
+  [Illustration: FIG. 80.  DIAGRAM OF THE PELVIS SEEN FROM BELOW IN AN
+  ORNITHOSAUR AND A DINOSAUR]
+
+The resemblances between Pterodactyles and Dinosaurs in the hind limb
+are not of less interest, though it is rather in the older Pterodactyles
+such as Dimorphodon, Pterodactylus, and Rhamphorhynchus that the
+resemblance is closest with the slender carnivorous Dinosaurs. They
+never have the head of the thigh bone, femur, separated from its shaft
+by a constricted neck, as in the Pterodactyles from the Chalk. In many
+ways the thigh bone of Dinosaurs tends towards being Avian; while that
+of Pterodactyles inclines towards being Mammalian, but with a tendency
+to be Bird-like in the older types, and to be Mammal-like in the most
+recent representatives of the group in the Chalk.
+
+The bones of the leg in Ornithosaurs, known as tibia and fibula, are
+remarkable for the circumstance first that they resemble Birds in the
+fibula being slender and only developed in its upper part towards the
+femur, and secondly that in a genus like Dimorphodon this drum-stick
+bone has the two upper bones of the ankle blended with the tibia, so as
+to form a rounded pulley joint which is indistinguishable from that of a
+Bird (see p. 102). There is a large number of Dinosaurs in which this
+remarkable distinctive character of Birds is also found. Only, Dinosaurs
+like Iguanodon, for instance, have the slender fibula as long as the
+tibia, and contributing to unite with the separate ankle bones of the
+similarly rounded pulley at the lower end. There are no Birds in which
+the tarsal bones remain separated and distinct throughout life. But in
+Pterodactylus from Solenhofen, as in a number of Dinosaurs, especially
+the carnivorous genera, the bones of the tarsus remain distinct
+throughout life, and never acquired such forms as would have enabled the
+ankle bone, termed astragalus, to embrace the extremity of the tibia, as
+it does in Iguanodon. Thus the resemblance of the Ornithosaur drum-stick
+is almost as close to Dinosaurs as to Birds.
+
+There is great similarity between Dinosaurs and Pterodactyles seen in
+the region of the instep, known as the metatarsus. These bones are
+usually four in number, parallel to each other, and similar in form.
+They are commonly longer than in Dinosaurs; but among some of the
+carnivorous Dinosaurs their length approximates to that seen in
+Pterodactyles. In neither group are the bones blended together by bony
+union, while they are always united in Birds, as in Oxen and similar
+even-hoofed mammals. Dinosaurs agree with Pterodactyles in maintaining
+the metatarsal bones separate, but they differ from them and agree with
+Birds frequently, in having the number of metatarsal bones reduced to
+three, as in Iguanodon, though Dinosaurs often have as many as five
+digits developed.
+
+The toe bones, the phalanges of these digits of the hind limb, are
+usually longer in Pterodactyles than in Dinosaurs, but they resemble
+carnivorous Dinosaurs in the forms of their sharp terminal bones for the
+claws, which are similarly compressed from side to side.
+
+So diverse are the functions of the fore limb in Dinosaurs and
+Pterodactyles, and so remarkably does the length of the metacarpal
+region of the back of the hand vary in the long-tailed and short-tailed
+Ornithosaurs, that there is necessarily a less close correspondence in
+that region of the skeleton between these two groups of animals; for the
+Pterodactyle fore limb is modified in relation to a function which can
+only be paralleled among Birds and Bats; and yet neither of those groups
+of animals approximates closely in this region of the skeleton to the
+Flying Reptile. Under all the modifications of structure which may be
+attributed to differences of function, some resemblance to Dinosaurs may
+be detected, which is best evident in the upper arm bone, humerus; is
+slight in the fore-arm bones, ulna and radius; and becomes lost towards
+the extremity of the limb.
+
+If the tendency of the thigh bone to resemble a Mammalian type of femur
+(p. 100) is a fundamental, deep-seated character of the skeleton, it
+might be anticipated that a trace of Mammalian character would also be
+found in the humerus. For what the character is worth, the head of the
+humerus does show a closer approximation to a Monotreme Mammal than is
+seen in Birds, and is to some extent paralleled in those South African
+reptiles which approximate to Mammals most closely. Not the least
+remarkable of the many astonishing resemblances of these light aerial
+creatures to the more heavy bodied Dinosaurs is the circumstance that
+the humerus in both groups makes a not dissimilar approach to that of
+certain Mammals.
+
+These illustrations may be accepted as demonstrating a relationship
+between the Ornithosaurs and Dinosaurs now compared, which can only be
+explained as results of influence of a common parentage upon the forms
+of the bones. But more interesting than resemblances of that kind is the
+similarity that may be traced in the way in which air is introduced into
+cavities in the bones in both groups. In some of the imperfectly known
+Dinosaurs, like Aristosuchus, Coelurus, and Thecospondylus, the bone
+texture is as thin as in Pterodactyles, and the vertebrae are excavated
+by pneumatic cavities, which are amazing in size when compared with the
+corresponding structures in birds, for the vertebra is often hollowed
+out so that nothing remains but a thin external film like paper for its
+thickness. In the Dinosaurian genus Coelurus this condition is as well
+marked in the tail and back as it is in the neck. The essential
+difference from Birds appears to be that in the larger carnivorous
+Dinosaurs the pneumatic condition of the bones is confined to the
+vertebral column; while Birds and Pterodactyles have the pneumatic
+condition more conspicuously developed in the limb bones. The pneumatic
+skeleton, however, appears to be absent from the herbivorous types like
+Iguanodon and all Dinosaurs which have the Bird-like form of pelvis, and
+are most Bird-like in the forms of bones of the hind limb. It is
+possible that some of the carnivorous Dinosaurs also possessed limb
+bones with pneumatic cavities. Many of those bones are hollow with very
+thin walls. If their cavities were connected with the lungs the foramina
+are inconspicuous and unlike the immense holes seen in the sides of the
+vertebrae.
+
+According to the late Professor Marsh, the limbs of Coelurus and its
+allies, which at present are imperfectly known, are in some cases
+pneumatic. Therefore there is a closer fundamental resemblance between
+some carnivorous Dinosaurs and Pterodactyles than might have been
+anticipated. But the skull of Coelurus is unknown, and the fragments of
+the skeleton hitherto published are insufficient to do more than show
+that the two types were near in kindred, though distinct in habit. Each
+has elaborated a skeleton which owes much to the common stock which
+transmitted the vital organs, and the tendency of the bones to take
+special forms; but which also owes more than can be accurately measured
+to the action of muscles in shaping the bones and the influence of the
+mechanical conditions of daily life upon the growth of the bones in both
+of these orders of animals. Enough is known to prove that all Dinosaurs
+cannot be regarded as Ornithosaurs which have not acquired the power of
+flight; though the evidence would lead us to believe that the primitive
+Ornithosaur was a four-footed animal, before the wing finger became
+developed in the fore limb as a means of extending a patagial membrane,
+like the membrane which in the hind limb of Dimorphodon has bent the
+outermost digit of the foot upward and outward to support the
+corresponding organ of flight extending down the hind legs.
+
+It may thus be seen that the characters of Ornithosaurs which have
+already been spoken of as Reptilian, as distinguished from the
+resemblances to Birds, may now with more accuracy be regarded as
+Dinosaurian. The Dinosaurs, like Pterodactyles, must be regarded as
+intermediate in some respects between Reptiles and Birds. The
+resemblances enumerated would alone constitute a partial transition from
+the Reptile to the Bird, although no Dinosaurs have organs of flight;
+many are heavily armoured with plates of bone, and few, if any,
+approximate in the technical parts of the skeleton to the Bird class,
+except in the hind limbs. Yet Dinosaurs have sometimes been regarded as
+standing to Birds in the relation of ancestors, or as parallel to an
+ancestral stock.
+
+Before an attempt can be made to estimate the mutual relation of the
+Flying Reptiles to Dinosaurs on the one hand, and to Birds on the other,
+it may be well to remember that the resemblance of such a Dinosaur as
+Iguanodon to a Bird in its pelvis and hind limb is not more remarkable
+than that of Pterodactyles to Birds in the shoulder-girdle and bones of
+the fore limb. The keeled sternum, the long, slender coracoid bones and
+scapulae, are absolutely Bird-like in most Ornithosaurs; and that region
+of the skeleton only differs from Birds in the absence of a furculum
+which represents the clavicles, and is commonly named the
+"merry-thought." The elongated bones of the fore-arm and the hand,
+terminating in three sharp claws, are characters in which the fossil
+bird Archaeopteryx resembles the Pterodactyle Rhamphorhynchus, a
+resemblance which extends to a similar elongation of the tail. It is
+remarkable that the resemblance should be so close, since Archaeopteryx
+affords the only bird's skeleton known to be contemporary which can be
+compared with the Solenhofen Flying Reptiles. The resemblance may
+possibly be closer than has been imagined. The back of the head of
+Archaeopteryx is imperfectly preserved in the region of the quadrate
+bone, malar arch, and temporal vacuity. And till these are better known
+it cannot be affirmed that the back of the head is more Reptilian in
+Pterodactyles than in the oldest Birds. The side of the head in
+Archaeopteryx is distinguished by the nostril being far forward, the
+vacuity in front of the orbit being as large as in the Pterodactyle
+Scaphognathus from Solenhofen and other long-tailed Pterodactyles.
+
+
+
+
+CHAPTER XVIII
+
+HOW PTERODACTYLES MAY HAVE ORIGINATED
+
+
+Ornithosauria have many characters inseparably blended together which
+are otherwise distinctive of Reptiles, Birds, and Mammals, and
+associated with peculiar structures which are absent from all other
+animals. They are not quite alone in this incongruous combination of
+different types of animals in the same skeleton. Dinosaurs, which were
+contemporary with Ornithosaurs, approximate to them in blending
+characters of Birds with the structure of a Reptile and something of a
+Mammal in one animal. If an Ornithosaur is Reptilian in its backbone, in
+the articular ends of each vertebra having the cup in front and ball
+behind in the manner of Crocodiles, Serpents, and many Lizards, a
+Dinosaur like Iguanodon, which had the reversed condition of ball in
+front and cup behind in its early vertebrae, may be more Mammalian than
+Avian in a corresponding resemblance of the bones to the neck in hoofed
+Mammals. But while Pterodactyles are sometimes Mammalian in having the
+head of the thigh bone moulded as in carnivorous Mammals and Man, the
+corresponding bone in a Dinosaur is more like that of a Bird. And while
+the Pterodactyle shoulder-girdle is often absolutely Bird-like, that
+region in Dinosaurs can only be paralleled among Reptiles.
+
+Such combinations of diverse characters are not limited to animals which
+are extinct. There were not wanting scientific men who regarded the
+Platypus of Australia, when first sent to Europe, as an ingenious
+example of Eastern skill, in which an animal had been compounded
+artificially by blending the beak of a Bird with the body of a Mammal.
+Fuller knowledge of that remarkable animal has continuously intensified
+wonder at its combination of Mammal, Bird, and Reptile in a single
+animal. It has broken down the theoretical divisions between the higher
+Vertebrata, demonstrating that a Mammal may lay eggs like a Reptile or
+Bird, that the skull may include the reptilian characters of the malar
+arch and pre-frontal and post-frontal bones, otherwise unknown in
+Mammals and Birds. The groups of Mammals, Birds, and Reptiles now
+surviving on the earth prove to be less sharply defined from each other
+when the living and extinct types are considered together. But in
+Pterodactyles, Mammal Bird and Reptile lose their identity, as three
+colours would do when unequally mixed together.
+
+This mingling of characteristics of different animals is not to be
+attributed to interbreeding, but is the converse of the combination of
+characters found in hybrid animals. It is no exaggeration to say that
+there is a sense in which Mammal, Bird, Reptile, and the distinctive
+structures of the Ornithosaur, have simultaneously developed from one
+egg, in the body of one animal.
+
+The differences between those vertebrate types of animals consist
+chiefly in the way in which their organisation is modified, by one
+strain of characters being eliminated so that another becomes
+predominant, while a distinctive set of structures is elaborated in each
+class of animals. The earlier geological history of the higher
+Vertebrata is very imperfectly known, but the evidence tends to the
+inference that the older representatives of the several classes
+approximate to each other more closely than do their surviving
+representatives, so that in still earlier ages of time the distinction
+between them had not become recognisable. The relation of the great
+groups of animals to each other, among Vertebrata, is essentially a
+parallel relation, like the colours of the solar spectrum, or the
+parallel digits of the hand. It was natural, when only the surviving
+life on the earth was known, to imagine that animals were connected in a
+continuous chain by successive descent, but Mammals have given no
+evidence of approximation to Birds; and Birds discover no evidence that
+their ancestors were Reptiles, in the sense in which that word is used
+to define animals which now exist on the earth. When the variation which
+animals attain in their maturity and exhibit in development from the egg
+was first realised, it was imagined that Nature, by slow summing up and
+accumulation of differences which were observed, would so modify one
+animal type that it would pass into another. There is little evidence to
+support belief that the changes between the types of life have been
+wrought in that way. The history of fossil animals has not shown
+transitions of this kind from the lower to higher Vertebrata, but only
+intermediate, parallel groups of animals, analogous to those which
+survive, and distinct from them in the same way as surviving groups are
+distinct from each other. The circumstance that Mammals, Birds, and
+Reptiles are all known low down in the Secondary epoch of geological
+time, is favourable to the idea of their history being parallel rather
+than successive. Such a conception is supported by the theory of
+elimination of characters from groups of animals as the basis of their
+differentiation. This loss appears always to be accompanied by a
+corresponding gain of characters, which is more remarkable in the soft,
+vital organs than in the skeleton. The gain in higher Vertebrates in the
+bones is chiefly in the perfection of joints at their extremities; but
+the gain in brain, lungs, heart, and other soft parts is an elaboration
+of those structures and an increase in amount of tissue.
+
+The resemblances of Ornithosaurs to Mammals are the least conspicuous of
+their characters. Those seen in the upper arm bone and thigh bone are
+manifestly not derived from Mammals. They cannot be explained as
+adaptations of the bones to conditions of existence, because there is no
+community of habit to be inferred between Pterodactyles and Mammals, in
+which the bones are in any way comparable.
+
+Other fossil animals show that a fundamentally Reptilian structure is
+capable of developing in the Mammalian direction in the skull, backbone,
+shoulder-girdle, hip-girdle, and limbs, so as to be uniformly Mammalian
+in its tendencies. This is proved by tracing the North American Texas
+fossils named Labyrinthodonts, through the South African Theriodonts,
+towards the Monotremata and other Mammalia. Just as those animals have
+obliterated all traces of the Bird from their skeletons, Birds have
+obliterated the distinctive characters of Mammals. The Ornithosaur has
+partially obliterated both. With a skull and backbone marked by typical
+characters of the Reptile, it combines the shoulder-girdle and
+hip-girdle of a Bird, with characters in the limbs which suggest both
+those types in combination with Mammals.
+
+The bones have been compared in the skeleton of each order of existing
+Reptiles, and found to show side by side with their peculiar characters
+not only resemblances to the other Reptilia, but an appreciable number
+of Mammalian and Avian characters in their skeletons. The term
+"crocodile," for example, indicates an animal in which the skeleton is
+dominated by one set of peculiar characters. Crocodiles retain enough of
+the characteristics of several other orders of reptiles to show that an
+animal sprung from the old Crocodile stock might diverge widely from
+existing Crocodiles by intensifying what might be termed its dormant
+characters in the Crocodile skeleton. Comparing animals together bone by
+bone it is possible to value the modifications of form which they put
+on, and the resemblances between them, so as to separate the inherited
+wealth of an animal's affinities with ancestors or collateral groups,
+from the peculiar characters which have been acquired as an increase
+based upon its typical bony possessions or osteological capital. There
+is no part of the Pterodactyle skeleton which is more distinctly
+modified than the head of the upper arm bone, which fits into the socket
+between the coracoid bone and the shoulder-blade. The head of the
+humerus, as the articular part is named, is somewhat crescent-shaped,
+convex on its inner border, and a little concave on its outer border,
+and therefore unlike the ball-shaped head of the upper arm bone in Man
+and the higher Mammals. It is much more nearly paralleled in the little
+group of Monotremata allied to the living Ornithorhynchus. In that sense
+the head of the humerus in a Pterodactyle has some affinity with the
+lowest Mammalia, which approach nearest to Reptiles. The character might
+pass unregarded if it were not found in more striking development in
+fossil Reptiles from Cape Colony, which from having teeth like Mammals
+are named Theriodontia. In several of those South African reptiles the
+upper arm bone approaches closer to the humerus in Ornithosaurs than to
+Ornithorhynchus. Such coincidences of structure are sometimes dismissed
+from consideration and placed beyond investigation by being termed
+adaptive modifications; but there can be no hope of finding community of
+habit between the burrowing Monotreme, the short-limbed Theriodont, and
+the flying Pterodactyle which might have caused this articular part of
+the upper arm bone to acquire a form so similar in animals constructed
+so differently. If the resemblance in the humerus to Monotremes in this
+respect is not to be attributed to burrowing, neither can the crescent
+form of its upper articulation be attributed to flight; for in Birds the
+head of the bone is compressed, but always convex, and Bats fly without
+any approach to the Pterodactyle form in the head of the humerus. This
+apparently trivial character may from such comparisons be inferred to be
+something which the way of life of the animal does not sufficiently
+account for. These deepest-seated parts of the limbs are slow to adapt
+themselves to changing circumstances of existence, and retain their
+characters with moderate variation of the bones in each of the orders
+or classes of animals. It therefore is safer to regard Mammalian
+characters, as well as the resemblances which Pterodactyles show to
+other kinds of animals, as due to inheritance from a time when there was
+a common stock from which none of these animals which have been
+considered had been distinctly elaborated.
+
+A few characters of Ornithosaurs are regarded as having been acquired,
+because they are not found in any other animals, or have been developed
+only in a portion of the group. The most obvious of these is the
+elongated wing finger; but in some genera, like Dimorphodon, there is
+also a less elongation of the fifth digit of the foot, and perhaps in
+all genera there is a backward development of the first digit of the
+hand, which is without a claw, and therefore unlike the clawed digit of
+a Bat. An acquired character of another kind, which is limited to the
+Cretaceous genera, is seen in the shoulder-blade being directed
+transversely outward, so that its truncated end articulates by a true
+joint with the early vertebrae of the back, and defended the cavity
+inclosed by the ribs by a strong bony external arch. And finally, as the
+animals later in time acquire short tails, and relatively longer limbs,
+the bones of the back of the hand, termed metacarpals, acquire greater
+and distinctive length, which is not seen in the long-tailed types like
+Rhamphorhynchus.
+
+These and such-like acquired characters distinguish the class of animals
+from all groups with which it may be compared, and mark the possible
+limits of variation of the skeleton within the boundary of the order.
+But no further variation of these parts of the skeleton could make a
+transition to another order of animals, or explain how the
+Pterodactyles came into existence, because the characters which separate
+orders and classes of animals from each other differ in kind from those
+which separate smaller groups, named genera and species, of which the
+order is made up. The accumulation of the characters of genera will not
+sum up into the characters of an order or class.
+
+In making the division of Vertebrate animals into classes the skeleton
+is often almost ignored. Its value is entirely empirical and based upon
+the observed association of the various forms of bones with the more
+important characters of the brain and other vital organs. What is
+understood as a Mammalian or Avian character in the skeleton is the form
+of bone which is found in association with the soft vital organs which
+constitute an animal a Mammal or a Bird.
+
+The characters which theoretically define a Mammal appear to be the
+enormous overgrowth of the cerebral hemispheres of the brain by which
+the cerebrum comes into contact with the cerebellum, as among Birds.
+This character distinguishes both groups of animals from all Reptiles,
+recent and fossil. But in examining the mould of the interior of the
+brain case it is rare to have the bones fitting so closely to the brain
+as to prove that the lateral expansion below the cerebrum and cerebellum
+is formed by the optic lobes of the brain. Otherwise the brain of a
+Pterodactyle might be as like to the brain of Ornithorhynchus as it is
+like that of a Bird (Fig. 19). But it is precisely in this condition of
+arrangement of the parts of the brain that the specimens appear to be
+most clear. The lateral mass of brain in specimens of Ornithosaurs from
+the Lower Secondary rocks appears to be transversely divided into back
+and front parts, which may be thought to correspond to the structures in
+a Mammal brain named _corpora quadrigemina_, but to be placed as the
+optic lobes are placed in Birds, and to have relatively greater
+dimensions than in Mammals. No evidence has been observed of this
+transverse division of the optic lobes of the brain in Pterodactyles
+from the Chalk and Cretaceous rocks, and so far as the evidence goes
+this part of the brain was shaped as in birds, but rather smaller.
+
+The brain is the only soft organ in which a Mammalian character could be
+evidenced. The uniformity in character of the brain throughout the group
+in Mammals is remarkable, in reference to the circumstance that the
+reproduction varies in type; the lowest, or Monotreme division, being
+oviparous. If there is no necessary connexion between the Mammalian
+brain and the prevalent condition under which the young are produced
+alive, it may be affirmed also that there is no necessary connexion
+between the form of the brain and the form of the bones, since the brain
+cavity in Theriodont reptiles shows no resemblance to that of a Mammal,
+while the bones are in so many respects only paralleled among
+Monotremata and Mammalia. The variety of forms which the existing
+Mammalian orders of animals assume, shows the astonishing range of
+structure of the skeleton which may coexist with the Mammalian brain.
+And therefore we are led to the conclusion that any other fundamental
+modification of brain--such as distinguishes the class of Birds--might
+also be associated with forms and structures of the skeleton which
+would vary in similar ways. In other words, if for convenience we define
+a Mammal by its form of brain, structure of the heart and lungs, and
+provision for nutrition of the young, without regard to the covering of
+the skin, which varies between the scales of a pangolin and the
+practically naked skin of the whale--a bird might be also defined by its
+peculiar conditions of brain and lungs, without reference to the
+feathered condition of the skin, though the feathered condition extends
+backward in time to the Upper Secondary rocks, as seen in the
+Archaeopteryx.
+
+The Avian characters of Pterodactyles are the predominant parts of their
+organisation, for the conditions of the brain and lungs shown by the
+moulds of the brain case and the thin hollow bones with conspicuous
+pneumatic foramina, give evidence of a community of vital structures
+with Birds, which is supported by characters of the skeleton. If any
+classificational value can be associated with the distribution of the
+pneumatic foramina as tending to establish membership of the same class
+for animals fashioned on the same plan of soft organs, the evidence is
+not weakened when a community of structures is found to extend among the
+bones to such distinctive parts of the skeleton as the sternum,
+shoulder-girdle, bones of the fore-arm and fore-leg; for in all these
+regions the Pterodactyle bones are practically indistinguishable from
+those of Birds. This is the more remarkable because other parts of the
+skeleton, such as the humerus and pelvis, show a partial resemblance to
+Birds, while the parts which are least Avian, like the neck bones, have
+no tendency to vary the number of the vertebrae, in the way which is
+common among Birds, following more closely the formula of the seven
+cervical vertebrae of Mammals.
+
+It would therefore appear from the vital community of structures with
+Birds, that Pterodactyles and Birds are two parallel groups, which may
+be regarded as ancient divergent forks of the same branch of animal
+life, which became distinguished from each other by acquiring the
+different condition of the skin, and the structures which were developed
+in consequence of the bony skeleton ministering to flight in different
+ways; and with different habit of terrestrial progression, this extinct
+group of animals acquired some modifications of the skeleton which Birds
+have not shown. There is nothing to suggest that Pterodactyles are a
+branch from Birds, but their relation to Birds is much closer, so far as
+the skeleton goes, than is their relation with the flightless Dinosaurs,
+with which Birds and Pterodactyles have many characters in common.
+
+On the theory of elimination of character which I have used to account
+for the disappearance of some Mammalian characters from the
+Pterodactyle, that loss is seen chiefly in the removal of the parts
+which have left a Reptilian articulation of the lower jaw with the
+skull, and the articulation of the vertebrae throughout the vertebral
+column by a modified cup-and-ball form of joint. The furculum of the
+Bird is always absent from the Pterodactyle. No specimen has shown
+recognisable clavicles or collar-bones. Judged by the standard of
+existing life, Pterodactyles belong to the same group as Birds, on the
+evidence of brain and lungs, but they belong to a different group on
+account of the dissimilar modifications of the skeleton and apparent
+absence of feathers from the skin.
+
+The most impressive facts in the Pterodactyle skeleton, in view of these
+affinities, are the structures which it has in common with Reptiles.
+Some structures are fundamental, like the cup-and-ball articulation of
+the vertebrae, which is never found in birds or mammals. Although not
+quite identical with the condition in any Reptile, this structure is
+approximately Lizard-like or Crocodile-like in the cup-and-ball
+character. It shows that the deepest-seated part of the skeleton is
+Reptile-like, though it may not be more Reptilian than is the vertebral
+column of a Mammal, if comparison is made between Mammals and extinct
+groups of animals known as Reptiles, such as Dinosaurs and Theriodontia.
+
+The orders of animals which have been included under the name Reptilia
+comprise such different structural conditions of the parts of the
+skeleton which may be termed reptilian in Ornithosaurs, that there is
+good reason for regarding the cup-and-ball articulation as quite a
+distinctive Reptilian specialisation, in the same sense that the
+saddle-shaped articulation between the bodies of adjacent vertebrae in a
+bird is an Avian specialisation. From the theoretical point of view the
+Ornithosaur acquired its Reptilian characters simultaneously with its
+Avian and Mammalian characters.
+
+There is nothing in the structure of the skeleton of the Dinosauria, to
+which Ornithosaurs approximate in several parts of the body, which would
+help to explain the cup-and-ball articulation of the backbone, if the
+Flying Reptile were supposed to be an offshoot from the carnivorous
+Dinosaurs.
+
+The elimination of Reptile characters from so much of the skeleton, and
+the substitution for them of the characters of Birds and Mammals, would
+be of exceptional interest if there had been any ground for regarding
+the flying animal as more nearly related to a Reptile than to a Bird.
+But if the evidence from the form of the brain and nature of the
+pneumatic organs seen in the limb bones accounts for the Avian features
+of the skeleton, the Reptilian condition of the vertebral column helps
+to show a capacity for variation, and that the fixity of type and
+structure, which the skeleton of the modern Bird has attained, is not
+necessarily limited to or associated with the vital organs of Birds.
+
+The variation of the cup-and-ball articulation in the neck of a
+Chelonian, which makes the third vertebra cupped behind, the fourth
+bi-convex, the fifth cupped in front, and the sixth flattened behind,
+shows that too much importance may be attached to the mode of union of
+these bones in Serpents, Crocodiles, and those Lizards which have the
+cup in front; for while in Lizards the anterior cup, oblique and
+depressed, is found in most of its groups, the Geckos show no trace of
+the cup-and-ball structure, and in that respect resemble the Hatteria of
+New Zealand.
+
+If, therefore, the cup-and-ball articulation of vertebrae in
+Ornithosauria has any significance as a mark of affinity to Reptiles, it
+could only be in approximation to those living Reptiles which possess
+the same character, and would have it on the hypothesis that both have
+preserved the structure by descent from an earlier type of animal. This
+hypothesis is negatived by the fact that the cup-and-ball articulation
+is unknown in the older fossil Reptiles.
+
+Although the articulation for the lower jaw with the skull in
+Ornithosaurs is only to be paralleled among Reptiles, the structure is
+adapted to a brain case which is practically indistinguishable from that
+of a Bird, except for the postorbital arch.
+
+The hypothesis of descent, therefore, becomes impossible, in any
+intelligible form, in explanation of distinctive character of the
+skeleton. The hypothesis of elimination may also seem to be
+insufficient, unless the potential capacity for new development be
+recognised as concurrent, and as capable of modifying each region of the
+skeleton, or hard parts of the animal, in the same way that the soft
+organs may be modified. From which we infer that all structures, which
+distinguish the several grades of organisation in modern
+classifications, soft parts and hard parts alike, may come into
+existence together, in so far as they are compatible with each other, in
+any class or ordinal division of animals.
+
+Although the young Mammal passes through a stage of growth in which the
+brain may be said to be Reptilian, there is no good ground for inferring
+that Mammal or Bird type of skeleton was developed later in time than
+that of Reptiles. The various types of Fishes have the brains in general
+so similar to those of Reptiles that it is more intelligible for all the
+vertebrate forms of brain to have differentiated at the same time, under
+the law of elimination of characters, than that there should be any
+other bond of union between the classes of animals.
+
+If we ask what started the Ornithosauria into existence, and created the
+plan of construction of that animal type, I think science is justified
+in boldly affirming that the initial cause can only be sought under the
+development of patagial membranes, such as have been seen in various
+animals ministering to flight. Such membranes, in an animal which was
+potentially a Bird in its vital organs, have owed development to the
+absence of quill feathers. Thus the wing membrane may be the cause for
+the chief differences of the skeleton by which Ornithosaurs are
+separated from Birds, for the stretch of wing in one case is made by the
+skin attached to the bones, and in the other case by feathers on the
+skin so attached as to necessitate that the wing bones have different
+proportions from Ornithosaurs.
+
+It is a well-known observation that each great epoch of geological time
+has had its dominant forms of animal life, which, so far as the earth's
+history is known now, came into existence, lived their time, and were
+seen no more. In the same way the smaller groups of species and genera
+included in an ordinal group of animals or class have abounded, giving a
+tone to the life of each geological formation, until the vitality of the
+animal is exhausted, and the species becomes extinct or ceases to
+preponderate. This process is seen to be still modifying the life on the
+earth, when some kinds of animals and plants are introduced to new
+conditions. Plants appear to wage successful war more easily than
+animals. The introduction of the Cactus in some parts of Cape Colony has
+locally modified both the fauna and flora, just as the Anacharis
+introduced into England spread from Cambridge over the whole country,
+and became for many years the predominant form of plant life in the
+streams. The Rabbit in Australia is a historic pest. Something similar
+to this physical fertility and increase appears to take place under new
+circumstances in certain organs within the bodies of animals, by the
+development of structures previously unknown. A familiar example is seen
+in the internal anatomy of the Trout introduced into New Zealand, where
+the number of pyloric appendages about the stomach has become rapidly
+augmented, while the size and the form of the animal have changed. The
+rapidity with which some of these changes have been brought about would
+appear to show that Nature is capable of transforming animals more
+rapidly than might have been inferred from their uniform life under
+ordinary circumstances. Growth of the vital organs in this way may
+modify the distinctive form of any vital organ, brain or lungs, and thus
+as a consequence of modification of the internal structures due to
+changes of food and habit, bring a new group of animals into existence.
+And just as the group of animals ceases to predominate after a time, so
+there comes a limit to the continued internal development of vital
+structures as their energy fails, for each organ behaves to some extent
+like an independent organism.
+
+Under such explanations of the mutual relations of the parts of animals,
+and groups of animals, time ceases to be a factor of primary importance
+in their construction or elaboration. The supposed necessity for
+practically unlimited time to produce changes in the vital organs which
+separate animals into great orders or classes is a nightmare, born of
+hypothesis, and may be profitably dismissed. The geological evidence is
+too imperfect for dogmatism on speculative questions; but the nature of
+the affinities of Ornithosaurs to other animals has been established on
+a basis of comparison which has no need of theory to justify the facts.
+It is not improbable that the primary epoch of time, even as known at
+present, may be sufficiently long to contain the parent races from which
+Ornithosaurs and all their allies have arisen.
+
+In thus stating the relation of Ornithosaurs to other animals the Flying
+Reptile has been traced home to kindred, though not to its actual
+parents or birthplace. There is no geological history of the rapid or
+gradual development of the wing finger, and although the wing membrane
+may be accepted as its cause of existence, the wing finger is powerfully
+developed in the oldest known Pterodactyles as in their latest
+representatives.
+
+Pterodactyles show singularly little variation in structure in their
+geological history. We chronicle the loss of the tail and loss of teeth.
+There is also the loss of the outermost wing digit from the hind foot as
+a supporter of the wing membrane. But the other variations are in the
+length of the metacarpus, or of the neck, or head. One of the
+fundamental laws of life necessitates that when an animal type ceases to
+adapt its organisation and modify its structures to suit the altered
+circumstances forced upon it by revolutions of the earth's surface its
+life's history becomes broken. It must bend or break.
+
+The final disappearance of these animals from the earth's history in the
+Chalk may yet be modified by future discoveries, but the Flying Reptiles
+have vanished, in the same way as so many other groups of animals which
+were contemporary with them in the Secondary period of time. Such
+extinctions have been attributed to catastrophes, like the submergence
+of land, so that the habitations of animals became an area gradually
+decreasing in size, which at last disappeared. It appears also to be a
+law of life, illustrated by many extinct groups of animals, that they
+endure for geological ages, and having fought their battle in life's
+history, grow old and unable to continue the fight, and then disappear
+from the earth, giving place to more vigorous types adapted to live
+under new conditions.
+
+The extinct Pterodactyles hold a relation to Birds in the scheme of life
+not unlike that which Monotremata hold to other Mammals. Both are
+remarkable for the variety of their affinities and resemblances to
+Reptiles. The Ornithosauria have long passed away; the Monotremes are
+nearing extinction. Both appear to be supplanted by parallel groups
+which were their contemporaries. Birds now fill the earth in a way that
+Flying Reptiles never surpassed; but their flight is made in a different
+manner, and the wing is extended to support the animal in the air,
+chiefly by appendages to the skin.
+
+If these fossils have taught that Ornithosaurs have a community of soft
+vital organs with Dinosaurs and Birds, they have also gone some way
+towards proving that causes similar to those which determined the
+structural peculiarities of their bony framework, originated the special
+forms of respiratory organs and brain which lifted them out of
+association with existing Reptiles.
+
+
+These old flying animals sleep through geological ages, not without
+honour, for the study of their story has illuminated the mode of origin
+of animals which survive them, and in cleaving the rocks to display
+their bones we have opened a new page of the book of life.
+
+
+
+
+APPENDIX
+
+
+The best public collections of Ornithosaurian remains in England are
+in the British Museum (Natural History); Museum of Practical Geology,
+Royal College of Surgeons; the University Museum, Oxford; Geological
+Museum, Cambridge; and the Museum of the Philosophical Society at
+York.
+
+Detailed descriptions and original figures of the principal specimens
+mentioned or referred to may be found in the following writings:--
+
+  H. v. Meyer, _Reptilien aus dem Lithograph_. _Schiefer_. 1859. Folio.
+  v. Quenstedt, _Pterodactylus suevicus_. 1855. 4to.
+  Goldfuss, _Nova Acta Leopold_. XV.
+  v. Munster, _Nova Acta Leopold_. XV.
+  A. Wagner, _Abhandl. Bayerischen Akad._, vi., viii.
+  Cuvier, _Annales du Museum_, xiii. 1809.
+    "     _Ossemens fossiles_, v. 1824.
+  Buckland, _Geol. Trans._, ser. 2, iii.
+  R. Owen, _Palaeontographical Society_. 1851, 1859, 1860, 1870, 1874.
+  K. v. Zittel, _Palaeontographica_, xxix. 1882.
+  T. C. Winkler, _Mus. Teyler Archives_. 1874, 1883.
+  Oscar Fraas, _Palaeontographica_, xxv. 1878.
+  Anton Fritsch, _Boehm. Gesell. Sitzber_. 1881.
+  R. Lydekker, _Catalogue of Fossil Reptilia in British Museum_ I. 1888.
+  O. C. Marsh, _Amer. Jour. Science_. 1882, 1884.
+  S. W. Williston, _Kansas University Quarterly_. 1893, 1896.
+  E. T. Newton, _Phil. Trans. Royal Soc._ 1888, 1894.
+  H. G. Seeley, _Ornithosauria_. 8vo. 1870.
+      "         _Annals and Mag. Natural Hist._ 1870, 1871, 1890, 1891.
+      "         _Linn. Society_. 1874, 1875.
+      "         _Geol. Mag._ 1881.
+  Felix Pleininger, _Palaeontographica_. 1894, 1901.
+
+
+
+
+INDEX
+
+
+A
+
+  Abdominal ribs, 85, 154
+
+  Accumulation of characters, 220
+
+  Acetabulum, 95
+
+  Acquired characters, 219
+
+  Adjacent land, 136
+
+  Air cells, 10, 48
+
+  Albatross, 23, 36, 176
+
+  Alligator, brain, 53;
+    pelvis, 98
+
+  American Greensand, 185
+
+  -- ornithosaurs, 87, 126
+
+  Amphibia, 4, 191
+
+  Anabas, 17
+
+  Anacharis, 227
+
+  Anchisaurus, 199
+
+  Angle of lower jaw, 75
+
+  Ankle bones, 103, 195, 207
+
+  Anomodonts, 192
+
+  Ant-eater of Africa, 142;
+    India, 40;
+    South America, 40, 185
+
+  Apteryx, lungs, 48;
+    pelvis, 95
+
+  Aquatic mammals, 141
+
+  Aramis, scapular arch, 113
+
+  Archaeopteryx, 58, 76, 104, 130, 197, 211
+
+  Aristosuchus, 129, 190, 205, 209
+
+  Armadillo, 40, 141
+
+  Articulation of the jaw, 12, 75
+
+  Ashwell, 177
+
+  Atlantosaurus, 202
+
+  Atlas and axis, 80, 81
+
+  Aves, 190
+
+  Avian characters, 220, 222
+
+
+B
+
+  Backbone, 78, 84
+
+  Banz, 148
+
+  Barbastelle, 25
+
+  Barrington, 177
+
+  Barton, 177
+
+  Bat, 38, 110, 197;
+    sternum of, 107;
+    metacarpus, 128
+
+  Bavaria, 156, 185
+
+  Beak, horny, 74, 178
+
+  Bear, skull of, 12;
+    femur, 100
+
+  Bel and the Dragon, 15
+
+  Belodon, 202
+
+  Bird, 80, 110, 120
+
+  -- resemblances, 63, 65, 71, 95, 102, 108, 113, 119, 120, 211
+
+  Bird-reptile, 188
+
+  Bird wing, 128, 130
+
+  Birds in flight, 22;
+    with teeth, 76
+
+  Black-headed bunting, 47
+
+  Blainville, D. de, 30, 193
+
+  Blood, temperature of, 56
+
+  Bohemia, 34
+
+  Bonaparte, Prince Charles, 30
+
+  Bones of birds, variation in, 41
+
+  -- of reptiles, variation in, 42
+
+  -- about the brain, 69
+
+  -- in the back, 84
+
+  Bone texture, 59, 209
+
+  Bonn Museum, 32, 85, 156
+
+  Brain and breathing organs, 55
+
+  Brain cavity, in birds and reptiles, 52;
+    in mammals, 221, 226;
+    in Solenhofen pterodactyles, 54, 220
+
+  Brazil, 34
+
+  Breathing organs, 8
+
+  Bridgewater Treatise, 143
+
+  British Museum, 133, 183
+
+  Brixton, Isle of Wight, 55, 174
+
+  Buckland, Dean, 143, 148, 231
+
+  Burrowing limb, 38
+
+
+C
+
+  Cactus, 227
+
+  Calamospondylus, 203
+
+  Cambridge Greensand, 33, 89, 176
+
+  -- Museum, 177
+
+  Camel, 83
+
+  Campylognathus, 68, 71, 135;
+    size of, 149
+
+  Canary, 47
+
+  Carnivorous dinosaurs, 129
+
+  Carpus, 122
+
+  Caudal fin, 91, 161
+
+  -- vertebrae, 89, 92, 203
+
+  Ceratodus, 4, 5, 9, 17
+
+  Ceratosaurus, 203, 204
+
+  Cervical rib, 81
+
+  Cetacea, 40
+
+  Cetiosaurus, 198, 203
+
+  Chalinolobus, 25
+
+  Chalk, pterodactyles in, 136;
+    of Kansas, 103, 132
+
+  Chameleon, 17, 51, 70;
+    scapula, 112;
+    sternum, 107
+
+  Chameleonoidea, 191
+
+  Cheek bones, 178
+
+  Chelonia, 86, 112, 193
+
+  Chesterton, 177
+
+  Chlamydosaurus, 21
+
+  _Chrysochloris capensis_, 121
+
+  Classification, 192;
+    on pelvis characters, 195;
+    of dinosaurs, 198
+
+  Clavicles, 111, 112
+
+  Claw, 105, 116, 183, 208
+
+  Coelurus, 203, 209
+
+  Coldham Common, 177
+
+  Collar bone, 111
+
+  Collini, 27
+
+  Comparison with dinosaurs, 198;
+    of pelvis, 204, 206;
+    of skulls, 192, 199, 201
+
+  Cope, Professor, 31, 34
+
+  Coracoid, 109, 112, 113
+
+  Cordylomorpha, 191
+
+  Cormorant, 70, 174;
+    sternum, 108
+
+  Corpora quadrigemina, 221
+
+  Crisp, Dr., on pneumatic skeleton, 47
+
+  Crocodile, characters of, 217;
+    heart, 56;
+    lung, 9;
+    shoulder-girdle, 111;
+    skull, 46;
+    vertebrae, 79
+
+  Crocodilia, 190
+
+  Curlew, 68
+
+  Cuvier, 1, 27, 28, 54, 76, 77, 130, 231
+
+  Cycnorhamphus, 70, 94, 171, 173, 204
+
+  _Cycnorhamphus Fraasii_, 80, 96, 169
+
+  -- _suevicus_, 169, 170
+
+  Cypselus, 42
+
+
+D
+
+  _Dacelo gigantea_, 63
+
+  Darwin, 3
+
+  Davy, Dr. John, 142
+
+  Deuterosaurus, 97
+
+  Dicynodon, 200
+
+  _Dicynodon lacerticeps_, 71
+
+  Digits, of ostrich, 23;
+    of pterodactyle, 128
+
+  Digits with claws, 130;
+    foot bones in, 105
+
+  Dimorphodon, 63, 64, 66, 67, 73, 74, 83, 90, 102, 113, 143, 192, 194,
+          199, 201, 206
+
+  Dinosauria, 6, 77, 84, 87, 95, 129, 144, 198, 209
+
+  Dinosaurs from Lias, 135, 192;
+    from Elgin, 201, 207;
+    Stuttgart, 202;
+    Trias dinosaurs, 199, 200
+
+  Diopecephalus, 168
+
+  Diving birds, 23, 83, 102
+
+  Dolichosauria, 191
+
+  Dolphin, 107
+
+  Doratorhynchus, 173
+
+  Dorygnathus, 74, 148
+
+  Dragons, 3, 15, 17
+
+  Drumstick bone, 103, 195
+
+  Duck, 22, 83
+
+
+E
+
+  Echidna, 75, 76, 95, 100
+
+  Edentata, 185
+
+  Edentulous beak, 153
+
+  Eichstaedt, 32
+
+  Elephant, head of, 46
+
+  Enumeration of characters, 223, 225
+
+  Ephesus, winged figure, 16
+
+  Epiphysis to first phalange, 123
+
+  Exocoetus, 18
+
+  Extinctions, 129
+
+  Eye hole, 144;
+    sclerotic bones in, 65
+
+
+F
+
+  Farren, William, 34
+
+  Femur, 100
+
+  Fibula, 102, 183, 206
+
+  Fifth outer digit, 132;
+    in foot, 145
+
+  Figure from temple at Ephesus, 16
+
+  First phalange, 151
+
+  Fish-eating crocodile, 137
+
+  Flight, organs of, 17;
+    in bats, 25
+
+  Flying limb, 38
+
+  Flying fishes, 18, 57;
+    foxes, 26;
+    frogs, 19, 197;
+    gecko, 21, 24;
+    lizards, 20;
+    reptiles, 37, 46;
+    squirrel, 24
+
+  Foot, 104;
+    digits in, 105, 146
+
+  Fore leg, 102, 206
+
+  -- limb, 38, 107, 116, 120
+
+  Four claws, 147
+
+  Fox, Rev. W., 55, 174
+
+  Fraas, Professor Oscar, 172, 231
+
+  Frigate bird, vertebrae of, 86, 174
+
+  Frog, lungs of, 8
+
+  Furculum, 114
+
+
+G
+
+  Gaudry, Professor A., 31
+
+  Gavial, 136
+
+  Gecko, 21, 23
+
+  Genera, comparison of, 192
+
+  Geological distribution, 186
+
+  Gills, 4
+
+  Giraffe, 38, 39
+
+  Glossy starling, 47
+
+  Golden eagle, 120
+
+  -- mole, 121
+
+  Goldfuss, 30, 231
+
+  Granchester, 177
+
+  Great ant-eater, 40, 185
+
+  Guillemot, 102
+
+  Gull, 22
+
+
+H
+
+  Haarlem, Teyler Museum at, 32
+
+  Habits, probable, 134, 176, 198
+
+  Hairless skins, 141
+
+  Hand in mammals, 38
+
+  Harston, 177
+
+  Haslingfield, 177
+
+  Hastings, 174
+
+  Hatteria lung, 9, 27;
+    brain, 53;
+    skull, 70, 77;
+    ribs, 86;
+    a reptile type, 13
+
+  Head, characters of, 76
+
+  Heidelberg Museum, 32, 54, 159
+
+  Herpetomorpha, 191
+
+  Heron, 65, 174
+
+  Hesperornis, 76
+
+  Hind foot, 104, 135
+
+  -- limb, 93, 99, 159, 206
+
+  Hip-girdle in whale tribe, 39, 159
+
+  Homoeosauria, 191
+
+  Horningsea, 177
+
+  Horse, metacarpus of, 127;
+    vertebrae of, 79
+
+  Humerus, 46, 117, 217
+
+  Huxley, Professor, 31, 89, 154, 188
+
+  Hyo-mandibular arch, 13
+
+  Hypothesis of descent, 226
+
+  Hyrax, 101
+
+
+I
+
+  Ichthyornis, 76
+
+  Ichthyosaurus, 6, 191
+
+  Iguanodon, 209;
+    pelvis, 206
+
+  Ilium, 93, 95, 96, 98, 204
+
+  Instep, 105, 207
+
+  Inherited characters, 217
+
+  Interclavicle, 111
+
+  Ischium, 93, 96, 203, 204
+
+  Isle of Wight, 174
+
+
+J
+
+  Jaw, in birds, 12;
+    in fishes, 13;
+    in mammals, 12;
+    in reptiles, 13;
+    in pterodactyles, 63;
+    suspension of, 11, 74, 76
+
+  -- lower, 75
+
+
+K
+
+  Kansas, Chalk of, 72, 103, 115;
+    University Museum of, 181
+
+  Kelheim, 32
+
+  Keuper, 33
+
+  Kimeridge Clay, 132
+
+  Kingfisher, 63
+
+  Kiwi, 23
+
+
+L
+
+  Labyrinthodontia, 191
+
+  Lachrymal bones, 67
+
+  Laramie rocks, 34
+
+  Largest ornithosaur, 133
+
+  Lateral vacuities in skull, 147
+
+  Lawrence in Kansas, 181
+
+  Lengths of bones, 146
+
+  Lepidosiren, 17
+
+  Lias, 33
+
+  Lithographic Slate, 35, 156
+
+  Lizards, 20, 21, 27, 123
+
+  Llama, neck of, 79, 83
+
+  Loach, swim bladder of, 52
+
+  Lower jaw, 12, 74, 76, 149
+
+  Lumbar vertebrae, 89
+
+  Lungs, 47;
+    in apteryx, 48;
+    in chameleon, 51;
+    in ostrich, 49;
+    in reptiles, 8, 9, 51
+
+  Lydekker, R., 160, 169, 231
+
+  Lyme Regis, 33
+
+
+M
+
+  Macrocercus, palate of, 71
+
+  Malar bone, 67
+
+  Mallard, 22
+
+  Mammal, 8, 12, 24, 79, 53, 95
+
+  Mammalia, 38, 141
+
+  Mammalian characters, 12, 220
+
+  Mammoth, 141
+
+  Manis, 40, 57, 142
+
+  Manubrium of sternum, 108, 109, 183
+
+  Marrow bones in a bird, 134
+
+  Marsh, Professor O. C., 31, 72, 90, 115, 121, 131, 140, 160, 165,
+          180, 181, 210, 231
+
+  Marsupial, 70, 94, 99
+
+  Megalosaurus, 129, 198
+
+  Merganser, 108
+
+  Merry-thought, 114
+
+  Metacarpus, 116, 124, 126, 128, 130
+
+  Metatarsal bones, 104, 207, 208
+
+  Meyer, Hermann von, 31, 45, 46, 85, 105, 108, 121, 160, 192, 231
+
+  Moa of New Zealand, 35
+
+  Mole, humerus, 38;
+    sternum, 107
+
+  Monotremes, 70, 94, 111, 121, 185, 218
+
+  Mososaurus, 77
+
+  Movement of the leg, 101
+
+  Mugger, 137
+
+  Munich Museum, 32, 159
+
+  Munster, von, 231
+
+  Muschelkalk, 184
+
+  Museum, 32, 156, 231, 159;
+    Natural History, 133, 231
+
+  Myrmecophaga, 185
+
+
+N
+
+  Names of genera, 183
+
+  Natural History Museum, 38, 231
+
+  Neck, 79;
+    in Dimorphodon, 145;
+    in Giraffe, 39;
+    in Llama, 79;
+    in Pterodactyles, 80;
+    in Whales, 39
+
+  Newton, E. T., 55, 70, 158, 160, 201, 232
+
+  New Zealand Bat, 25
+
+  -- -- Hatteria, 68
+
+  Niobrara rock, 183
+
+  Nostril, bones round the, 62;
+    small, 147
+
+  Notarium, 87, 115
+
+  Nothosauria, 192
+
+  Nusplingen, 32
+
+  Nyctodactylus, 115, 180
+
+
+O
+
+  Obliteration of characters, 216
+
+  Opercular bones, 13
+
+  Ophidia, 52, 191
+
+  Optic lobes, 53, 221
+
+  Organs of flight, 17
+
+  Ornithischia, 190, 198
+
+  Ornithocephalus, 166
+
+  Ornithocheirus, atlas and axis, 81;
+    brain, 55, 69;
+    carpus, 124;
+    cervical vertebra, 83, 179;
+    claw phalange, 129;
+    coracoid, 109;
+    femur, 100;
+    pelvis, 98;
+    pubic bones, 194;
+    sternum, 109;
+    shoulder-girdle, 115;
+    remains, 176;
+    teeth, 74, 76;
+    absence of teeth, 138
+
+  _Ornithocheirus machaerorhynchus_, 139;
+    _microdon_, 139
+
+  Ornithocheiroidea, 193
+
+  Ornithodesmus, neck bones, 173, 175;
+    coracoid, 109, 116;
+    dorsal vertebrae, 86;
+    remains of _O. latidens_, 173;
+    _O. sagittirostris_, 175
+
+  Ornithomorpha, 189
+
+  Ornithorhynchus, 40, 53, 95, 117
+
+  Ornithosauria, 30, 31, 50, 52, 58, 72, 89, 95, 104, 108, 125, 132,
+          133, 143, 187, 190, 192, 216
+
+  Ornithostoma, 66, 69, 72, 180;
+    lower jaw, 75, 76;
+    pelvis, 98;
+    sternum, 110;
+    phalange, 122;
+    size, 133;
+    skull, 181, 182
+
+  Ornithosuchus, 201
+
+  Orycteropus, 96
+
+  _Ossa innominata_, 93
+
+  Ossified ligaments, 150
+
+  Ostrich, 23, 45, 49, 113, 129
+
+  Owen, Sir R., 31, 36, 46, 48, 110, 117, 143, 172, 176, 180, 231
+
+  Owl, 46, 53
+
+  Oxford Clay, 33, 156
+
+  -- University Museum, 154
+
+  Ox, vertebra of, 79;
+    metacarpus, 127
+
+
+P
+
+  Palate, bones of, 71
+
+  Pangolin, 142
+
+  Pappenheim, 32
+
+  Parallel groups, 215
+
+  Parrot, 71
+
+  Patagial membranes, 227
+
+  Pelican, 174
+
+  Pelvis, 88, 94-98, 151, 195, 202, 204, 206
+
+  Penguin, 41, 42, 104, 176
+
+  Periophthalmus, 17
+
+  Peterborough, bones from, 113, 156
+
+  Phalanges, 129, 132;
+    wing finger, 155
+
+  Phillips, Professor John, 155
+
+  Pigeon, 119
+
+  Platydactylus, 21
+
+  Platypus, 214
+
+  Plesiosaurus, 6, 73, 75, 93, 189
+
+  Pleininger, 149, 232
+
+  Pneumatic foramina, 45, 83, 88, 132, 209
+
+  Pond, Mr., 34
+
+  Porcupine, 40
+
+  Porpoise, 38, 73, 141, 200
+
+  Premaxillary bones, 77, 200, 205
+
+  Prepubic bones, 94, 96-98, 194, 204, 205
+
+  Protorosauria, 192
+
+  _Ptenodracon brevirostris_, 64, 99, 167, 169, 192
+
+  Pterodactyle aspects, 35;
+    avian characters, 222;
+    beak, 200;
+    brain, 53;
+    coracoid, 113;
+    discovery, 27, 33;
+    foot, 104;
+    fore limb, 117;
+    history in Germany, 31, 148;
+    hand, 130;
+    hind limb, 100;
+    long tails, 156;
+    palate, 71;
+    sacrum, 89;
+    short tails, 165;
+    size, 35, 133;
+    sacrum, 89;
+    skull, 192;
+    teeth, 73;
+    vertebrae, 80
+
+  Pterodactyles from Kansas Chalk, 177, 181
+
+  -- from Lias Clay, 135, 147, 152
+
+  -- from Neocomian Sand, 176
+
+  -- from Oxford Clay, 155
+
+  -- from Purbeck beds, 173
+
+  -- from Solenhofen Slate, 156, 158
+
+  -- from Stonesfield Slate, 153, 158
+
+  Pterodactylia, 30, 165, 193, 199
+
+  _Pterodactylus antiquus_, 167;
+    _brevirostris_, 99, 167, 169;
+    _crassirostris_, 156;
+    _dubius_, 87, 96, 97, 203;
+    _elegans_, 169;
+    _Fraasii_, 169;
+    _grandipelvis_, 87, 90;
+    _grandis_, 102, 167, 169;
+    _Kochi_, 12, 61, 87, 90, 168, 169;
+    _longirostris_, 28, 90, 96, 101, 103, 105, 167, 169;
+    _micronyx_, 105, 169;
+    _rhamphastinus_, 183;
+    _scolopaciceps_, 105, 166;
+    _spectabilis_, 83;
+    _suevicus_, 169
+
+  Pterodermata, 194, 199
+
+  Pteroid bone of first digit, 121
+
+  Pteromys, 24
+
+  Pterosauria, 187, 193
+
+  Pterygoid bones, 72, 147
+
+  Pythonomorpha, 191
+
+
+Q
+
+  Quadrate bone, 12, 68, 77
+
+  Quenstedt, 231
+
+
+R
+
+  Rabbit, 227
+
+  Radius, 119, 120
+
+  Redshanks, 22
+
+  Relation between head and tail, 157, 193
+
+  Reptile, 6, 79, 80
+
+  Resin, 136
+
+  Restorations--
+    Campylognathus, palate of, 71
+    Dimorphodon, 143, 147, 164
+    Ornithocheirus, 164
+    Ornithostoma, 164, 183
+    Ptenodracon, 167
+    Pterodactylus, 29, 30
+    Rhamphocephalus, 164
+    Rhamphorhynchus, 161, 164
+    Scaphognathus, 163
+
+  Rhacophorus, 19
+
+  Rhaetic beds, 184
+
+  Rhamphocephalus, 113, 136, 153
+
+  Rhamphorhynchus, 118, 192;
+    foot, 104;
+    hind limb, 99;
+    pelvis, 95;
+    sacrum, 88;
+    skull, 54, 63-6, 69;
+    sternum, 108;
+    tail, 91;
+    teeth, 73;
+    tibia and fibula, 103;
+    web-footed, 105
+
+  _Rhamphorhynchus curtimanus_, 163;
+    _hirundinaceus_, 163;
+    _longimanus_, 164;
+    _phyllurus_, 91, 165
+
+  Rhinoceros, 40, 141
+
+  Rhopoladon, 97
+
+  Rhynchocephala, 192
+
+  Roc, 36
+
+  Rochester, 136
+
+  Running limb, 38
+
+  Ryle, Bishop, 17
+
+
+S
+
+  Sacrum, 87, 88
+
+  St. George, 15
+
+  St. Ives, 156
+
+  Sarcorhamphus, 102
+
+  Saurians, 27
+
+  Saurischia, 190, 195, 198, 199
+
+  Sauromorpha, 191, 192
+
+  Sauropsida, 188
+
+  Sauropterygia, 192
+
+  Scaphognathus, 64, 85, 140, 152, 192, 212
+
+  _Scaphognathus crassirostris_, 73-5, 83
+
+  Scapular arch, 111, 113
+
+  Scelidosaurus, 135
+
+  Sclerotic circle, 65
+
+  Seals, 41
+
+  Sedgwick, Professor Adam, v, 46
+
+  Shillington, 77
+
+  Shoebill, 67
+
+  Shoe-shaped prepubic bones, 204, 205
+
+  Short-tailed pterodactyles, 165, 193
+
+  Shoulder-girdle, 107, 111, 114, 115, 183
+
+  Siberia, 141
+
+  Simultaneous origin of characters, 214, 224
+
+  Skin covering, 40, 41, 58, 139, 140
+
+  Skulls, 68
+
+  Sloth, 112
+
+  Snipe, 47, 68
+
+  Solenhofen Slate, 28, 32, 88, 153, 156
+
+  Soemmerring, 29
+
+  South African reptiles, 188, 208, 216
+
+  Spotted fly-catcher, 47
+
+  Squamosal bone, 12, 13
+
+  Sternal ribs, 110
+
+  Sternum, 107, 158
+
+  Stonesfield Slate, 33, 88, 153
+
+  Structures common to reptiles, 224
+
+  Stuttgart Museum, 32, 172, 203
+
+  Swanage, 172
+
+  Swan, neck of, 80, 113
+
+  Swift, 50
+
+  Swimming limb, 38
+
+  Synotus, 25
+
+  Syrinx, 48
+
+
+T
+
+  Tail, description of, 90;
+    in Cretaceous Pterodactyles, 193
+    -- long, 156;
+    short, 166;
+    in Dimorphodon, 145;
+    in Ornithocheirus, 179
+
+  Tanystrophoeus, long vertebrae in, 79
+
+  Tarsal bones, 102, 207
+
+  Tarso-metatarsus, 128
+
+  Teeth, 73, 137, 138;
+    in porpoise, 40
+
+  Temperature of blood, 56
+
+  Temporal arches, 68
+
+  -- bone, 12
+
+  -- fossa, 67
+
+  Teredo, 137
+
+  Texas fossils, 216
+
+  Thecospondylus, 209
+
+  Theriodont pelvis, 97
+
+  -- reptiles, 75;
+    of Russia, 96, 97;
+    of South Africa, 96, 117
+
+  Theropsida, 188
+
+  Thigh bone, 100, 206, 211
+
+  Three claws, 146, 197
+
+  Tibia, 102, 195;
+    in Iguanodon, 207
+
+  Toothless mammals, 40
+
+  -- pterodactyles, 138, 181;
+    beak of pterodactyles, 150
+
+  Transition from reptiles to birds, 211
+
+  Tree frogs, 21
+
+  Trias dinosaurs, 199
+
+  Triceratops, pelvis of, 204
+
+  Trout, 139;
+    of New Zealand, 228
+
+  Tuatera, 13
+
+  Tuebingen Museum, 32
+
+  Tundras, 141
+
+  Tunny, 57
+
+  Turtles, neck bones, 79
+
+
+U
+
+  Ulna, description of, 119
+
+  Uncinate process of ribs, 85
+
+  Unlimited time, 228
+
+  Upper arm bone, 117
+
+  -- Greensand, remains in, 136
+
+  -- Lias of Whitby, 147
+
+  -- Oolites, 185, 195
+
+
+V
+
+  Variation of bones in mammals, 38
+
+  -- in Pterodactyles, 229
+
+  Variation of bones in vertebrae, 225
+
+  Vertebrae, caudal, 89, 92, 203
+
+  -- cervical, 173, 179, 203
+
+  -- dorsal, 86
+
+  Vertebral articulation, 82, 224
+
+  -- column, 78
+
+  Vulture, neck vertebrae of, 80;
+    tibia and fibula of, 102
+
+  Vomer, 147
+
+  Vomerine bones, 72
+
+
+W
+
+  Wagler, 29
+
+  Wagner, Andreas, 30, 148, 231
+
+  Walker, J. F., 54
+
+  Wealden beds, Pterodactyles in, 55, 84;
+    bones in, 135, 136, 173
+
+  Weight of Pterodactyle, 106
+
+  Whinchat, 47
+
+  Whitby, 33, 135
+
+  Williston, Professor W. S., 75, 82, 92, 98, 105, 110
+
+  Willow-wren, 47
+
+  Wing finger, 116, 130, 133, 151, 178, 197
+
+  -- membrane, 32, 121, 140, and frontispiece
+
+  -- metacarpal, 123;
+    in Dimorphodon, 151;
+    in Ornithostoma, 184;
+    in bats, 131
+
+  Wings of Dragons, 16
+
+  Winkler, T. C., 231
+
+  Woodwardian Museum, 34
+
+  Wood-wren, 47
+
+  Wrist bones, 122
+
+  Wuertemberg, 33
+
+
+Y
+
+  Yale College Museum, 32
+
+  York Museum, 34, 176
+
+
+Z
+
+  Zittel, Karl von, 31, 157, 165, 231
+
+  Zygomatic arch, 67
+
+
+
+
+  PRINTED BY
+  WILLIAM BRENDON AND SON
+  PLYMOUTH
+
+
+
+
+
+End of the Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley
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