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+<title>The Project Gutenberg eBook of The Ancient Life History of the Earth, by Henry Alleyne Nicholson</title>
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+<body>
+<div>*** START OF THE PROJECT GUTENBERG EBOOK 14279 ***</div>
+
+<h1>
+<span class="smaller">THE</span><br />
+ANCIENT&nbsp;LIFE-HISTORY<br />
+<span class="smaller">OF</span><br />
+THE&nbsp;EARTH
+</h1>
+
+<p class="center">
+A COMPREHENSIVE OUTLINE OF THE PRINCIPLES AND LEADING FACTS OF
+PALÆONTOLOGICAL SCIENCE
+</p>
+
+<p class="center"><strong>
+BY<br />
+H. ALLEYNE NICHOLSON
+</strong></p>
+
+<p class="center">
+M.D., D.SC., M.A., PH. D. (G&Ouml;TT), F.R.S.E, F.L.S.
+</p>
+
+<p class="center">
+PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF ST ANDREWS
+</p>
+
+<h2>
+<a name="page_v"><span class="page">Page v</span></a>
+PREFACE.</h2>
+
+<hr />
+
+<p class="indent">
+The study of Palæontology, or the science which is concerned
+with the living beings which flourished upon the globe during
+past periods of its history, may be pursued by two parallel but
+essentially distinct paths. By the one method of inquiry, we may
+study the anatomical characters and structure of the innumerable
+extinct forms of life which lie buried in the rocks simply as so
+many organisms, with but a slight and secondary reference to
+the <i>time</i> at which they lived. By the other method, fossil
+animals are regarded principally as so many landmarks in the
+ancient records of the world, and are studied <i>historically</i>
+and as regards their relations to the chronological succession
+of the strata in which they are entombed. In so doing, it is of
+course impossible to wholly ignore their structural characters,
+and their relationships with animals now living upon the earth;
+but these points are held to occupy a subordinate place, and to
+require nothing more than a comparatively general attention.
+</p>
+
+<p class="indent">
+In a former work, the Author has endeavoured to furnish a summary
+of the more important facts of
+<a name="page_vi"><span class="page">Page vi</span></a>
+Palæontology regarded in its
+strictly scientific aspect, as a mere department of the great
+science of Biology. The present work, on the other hand, is an
+attempt to treat Palæontology more especially from its
+historical side, and in its more intimate relations with Geology.
+In accordance with this object, the introductory portion of the
+work is devoted to a consideration of the general principles of
+Palæontology, and the bearings of this science upon various
+geological problems&mdash;such as the mode of formation of the
+sedimentary rocks, the reactions of living beings upon the crust
+of the earth, and the sequence in time of the fossiliferous
+formations. The second portion of the work deals exclusively with
+Historical Palæontology, each formation being considered
+separately, as regards its lithological nature and subdivisions,
+its relations to other formations, its geographical distribution,
+its mode of origin, and its characteristic life-forms.
+</p>
+
+<p class="indent">
+In the consideration of the characteristic fossils of each successive
+period, a general account is given of their more important zoological
+characters and their relations to living forms; but the technical
+language of Zoology has been avoided, and the aid of illustrations
+has been freely called into use. It may therefore be hoped that
+the work may be found to be available for the purposes of both the
+Geological and the Zoological student; since it is essentially an
+outline of Historical Palæontology, and the student of either
+of the above-mentioned sciences must perforce possess some knowledge
+of the last. Whilst primarily intended for students, it may be added
+that the method of treatment adopted has been so far untechnical as
+not to render the work useless to the general reader who may desire
+<a name="page_vii"><span class="page">Page vii</span></a>
+to acquire some knowledge of a subject of such vast and universal
+interest.
+</p>
+
+<p class="indent">
+In carrying out the object which he has held before him, the
+Author can hardly expect, from the nature of the materials with
+which he has had to deal, that he has kept himself absolutely
+clear of errors, both of omission and commission. The subject,
+however, is one to which he has devoted the labour of many years,
+both in studying the researches of others and in personal
+investigations of his own; and he can only trust that such errors
+as may exist will be found to belong chiefly to the former class,
+and to be neither serious nor numerous. It need only be added
+that the work is necessarily very limited in its scope, and that
+the necessity of not assuming a thorough previous acquaintance
+with Natural History in the reader has inexorably restricted its
+range still further. The Author does not, therefore, profess to
+have given more than a merely general outline of the subject; and
+those who desire to obtain a more minute and detailed knowledge
+of Palæontology, must have recourse to other and more elaborate
+treatises.
+</p>
+
+<p>
+UNITED COLLEGE, ST ANDREWS.<br/>
+&nbsp;&nbsp;&nbsp;&nbsp;<i>October</i> 2, 1876.
+</p>
+
+<h2>
+<a name="page_ix"><span class="page">Page ix</span></a>
+CONTENTS.</h2>
+
+<hr />
+
+<p class="center"><strong>
+PART I.
+</strong></p>
+
+<p class="center"><strong>
+PRINCIPLES OF PALÆONTOLOGY.
+</strong></p>
+
+<p class="center">
+<a href="#page_1">
+INTRODUCTION.</a>
+</p>
+
+<p class="contents">
+The general objects or geological science&mdash;The older theories
+of catastrophistic and intermittent action&mdash;The more modern
+doctrines of continuous and uniform action&mdash;Bearing of these
+doctrines respectively on the origin or the existing terrestrial
+order&mdash;Elements or truth in Catastrophism&mdash;General truth
+of the doctrine of Continuity&mdash;Geological time.
+</p>
+
+<p class="center">
+<a href="#page_10">
+CHAPTER I.</a>
+</p>
+
+<p class="contents">
+Definition of Palæontology&mdash;Nature of
+Fossils&mdash;Different processes of fossilisation.
+</p>
+
+<p class="center">
+<a href="#page_14">
+CHAPTER II.</a>
+</p>
+
+<p class="contents">
+Aqueous and igneous rocks&mdash;General characters of the
+sedimentary rocks&mdash;Mode or formation of the sedimentary
+rocks&mdash;Definition of the term "formation"&mdash;Chief divisions
+of the aqueous rocks&mdash;Mechanically-formed rocks, their
+characters and mode of origin&mdash;Chemically and organically
+formed rocks&mdash;Calcareous rocks&mdash;Chalk, its microscopic
+structure and mode of formation&mdash;Limestone, varieties,
+structure, and origin&mdash;Phosphate of
+lime&mdash;Concretions&mdash;Sulphate of lime&mdash;Silica and
+siliceous deposits of various kinds&mdash;Greensands&mdash;Red
+clays&mdash;Carbon and carbonaceous deposits.
+</p>
+
+<p class="center">
+<a href="#page_37">
+CHAPTER III.</a>
+</p>
+
+<p class="contents">
+Chronological succession of the fossiliferous rocks&mdash;Tests
+or age of strata&mdash;Value of Palæontological evidence
+in stratigraphical Geology&mdash;General sequence of the great
+formations.
+</p>
+
+<p class="center">
+<a name="page_x"><span class="page">Page x</span></a>
+<a href="#page_44">
+CHAPTER IV.</a>
+</p>
+
+<p class="contents">
+The breaks in the palæontological and geological
+record&mdash;Use of the term "contemporaneous" as applied to
+groups of strata&mdash;General sequence of strata and of
+life-forms interfered with by more or less extensive
+gaps&mdash;Unconformability&mdash;Phenomena implied by
+this&mdash;Causes of the imperfection of the
+palæontological record.
+</p>
+
+<p class="center">
+<a href="#page_52">
+CHAPTER V.</a>
+</p>
+
+<p class="contents">
+Conclusions to be drawn from fossils&mdash;Age of rocks&mdash;Mode
+of origin of any fossiliferous bed&mdash;Fluviatile, lacustrine,
+and marine deposits&mdash;Conclusions as to climate&mdash;Proofs
+of elevation and subsidence of portions of the earth's crust
+derived from fossils.
+</p>
+
+<p class="center">
+<a href="#page_57">
+CHAPTER VI.</a>
+</p>
+
+<p class="contents">
+The biological relations of fossils&mdash;Extinction of
+life-forms&mdash;Geological range of different
+species&mdash;Persistent types of life&mdash;Modern origin of
+existing animals and plants&mdash;Reference of fossil forms to
+the existing primary divisions of the animal
+kingdom&mdash;Departure of the older types of life from those
+now in existence&mdash;Resemblance of the fossils of a given
+formation to those of the formation next above and next
+below&mdash;Introduction of new life-forms.
+</p>
+
+<hr />
+
+<p class="center"><strong>
+PART II.
+</strong></p>
+
+<p class="center"><strong>
+HISTORICAL PALÆONTOLOGY.
+</strong></p>
+
+<p class="center">
+<a href="#page_65">
+CHAPTER VII.</a>
+</p>
+
+<p class="contents">
+The Laurentian and Huronian periods&mdash;General nature, divisions,
+and geographical distribution of the Laurentian deposits&mdash;Lower
+and Upper Laurentian&mdash;Reasons for believing that the Laurentian
+rocks are not azoic based upon their containing limestones, beds of
+oxide of iron, and graphite&mdash;The characters, chemical
+composition, and minute structure of <i>Eozoön
+Canadense</i>&mdash;Comparison of <i>Eozoön</i> with existing
+Foraminifera&mdash;<i>Archœosphœrinœ</i>&mdash;Huronian
+formation&mdash;Nature and distribution of Huronian
+deposits&mdash;Organic remains of the Huronian&mdash;Literature.
+</p>
+
+<p class="center">
+<a href="#page_77">
+CHAPTER VIII.</a>
+</p>
+
+<p class="contents">
+The Cambrian period&mdash;General succession of Cambrian deposits in
+Wales&mdash;Lower Cambrian and Upper Cambrian&mdash;Cambrian deposits of
+the continent of Europe and North American&mdash;Life of the Cambrian
+period &mdash; Fucoids &mdash; Eophyton &mdash; Oldhamia &mdash; Sponges
+&mdash; Echinoderms &mdash; Annelides &mdash; Crustaceans &mdash;
+Structure of Trilobites&mdash;Brachiopods&mdash;Pteropods, Gasteropods,
+and Bivalves&mdash;Cephalopods&mdash;Literature.
+</p>
+
+<p class="center">
+<a name="page_xi"><span class="page">Page xi</span></a>
+<a href="#page_90">
+CHAPTER IX.</a>
+</p>
+
+<p class="contents">
+The Lower Silurian period&mdash;The Silurian rocks generally&mdash;Limits
+of Lower and Upper Silurian&mdash;General succession, subdivisions, and
+characters of the Lower Silurian rocks of Wales&mdash;General succession,
+subdivisions, and characters of the Lower Silurian rocks of the
+North American continent&mdash;Life of the period &mdash; Fucoids &mdash;
+Protozoa &mdash; Graptolites &mdash; Structure of Graptolites &mdash;
+Corals &mdash; General structure of Corals &mdash; Crinoids &mdash;
+Cystideans &mdash; General characters of Cystideans &mdash; Annelides
+&mdash; Crustaceans &mdash; Polyzoa &mdash; Brachiopods &mdash; Bivalve
+and Univalve Molluscs&mdash;Chambered Cephalopods&mdash;General
+characters of the Cephalopoda&mdash;Conodonts.
+</p>
+
+<p class="center">
+<a href="#page_115">
+CHAPTER X.</a>
+</p>
+
+<p class="contents">
+The Upper Silurian period&mdash;General succession of the Upper Silurian
+deposits of Wales&mdash;Upper Silurian deposits of North
+America&mdash;Life of the Upper Silurian &mdash; Plants &mdash; Protozoa
+&mdash; Graptolites &mdash; Corals &mdash; Crinoids &mdash; General
+structure of Crinoids &mdash; Star-fishes &mdash; Annelides &mdash;
+Crustaceans &mdash; Eurypterids &mdash; Polyzoa &mdash; Brachiopods
+&mdash; Structure of Brachiopods &mdash; Bivalves and Univalves &mdash;
+Pteropods &mdash; Cephalopods &mdash; Fishes &mdash; Silurian literature.
+</p>
+
+<p class="center">
+<a href="#page_132">
+CHAPTER XI.</a>
+</p>
+
+<p class="contents">
+The Devonian period&mdash;Relations between the Old Red Sandstone
+and the marine Devonian deposits&mdash;The Old Red Sandstone of
+Scotland&mdash;The Devonian strata of Devonshire&mdash;Sequence and
+subdivisions of the Devonian deposits of North America&mdash;Life of
+the period &mdash; Plants &mdash; Protozoa &mdash; Corals &mdash;
+Crinoids &mdash; Pentremites &mdash; Annelides &mdash; Crustaceans
+&mdash; Insects &mdash; Polyzoa &mdash; Brachiopods &mdash; Bivalves
+&mdash; Univalves &mdash; Pteropods &mdash; Cephalopods &mdash;
+Fishes &mdash; General divisions of the
+Fishes&mdash;Palæontological evidence as to the
+independent existence of the Devonian system as a distinct
+formation&mdash;Literature.
+</p>
+
+<p class="center">
+<a href="#page_157">
+CHAPTER XII.</a>
+</p>
+
+<p class="contents">
+The Carboniferous period&mdash;Relations of Carboniferous rocks to
+Devonian&mdash;The Carboniferous Limestone or Sub-Carboniferous
+series&mdash;The Millstone-grit and the Coal-measures&mdash;Life of
+the period&mdash;Structure and mode of formation of Coal&mdash;Plants
+of the Coal.
+</p>
+
+<p class="center">
+<a href="#page_170">
+CHAPTER XIII.</a>
+</p>
+
+<p class="contents">
+Animal life of the Carboniferous period &mdash; Protozoa &mdash;
+Corals &mdash; Crinoids &mdash; Pentremites &mdash; Structure of
+Pentremites &mdash; Echinoids &mdash; Structure of Echinoidea
+&mdash; Annelides &mdash; Crustacea &mdash; Insects &mdash;
+Arachnids &mdash; Myriapods &mdash; Polyzoa &mdash; Brachiopods
+&mdash; Bivalves and Univalves &mdash; Cephalopods &mdash; Fishes
+&mdash; Labyrinthodont Amphibians&mdash;Literature.
+</p>
+
+<p class="center">
+<a name="page_xii"><span class="page">Page xii</span></a>
+<a href="#page_192">
+CHAPTER XIV.</a>
+</p>
+
+<p class="contents">
+The Permian period &mdash; General succession, characters, and
+mode of formation of the Permian deposits &mdash; Life of the
+period &mdash; Plants &mdash; Protozoa &mdash; Corals &mdash;
+Echinoderms &mdash; Annelides &mdash; Crustaceans &mdash;
+Polyzoa &mdash; Brachiopods &mdash; Bivalves &mdash; Univalves
+&mdash; Pteropods &mdash; Cephalopods &mdash; Fishes &mdash;
+Amphibians &mdash; Reptiles &mdash; Literature.
+</p>
+
+<p class="center">
+<a href="#page_203">
+CHAPTER XV.</a>
+</p>
+
+<p class="contents">
+The Triassic period-&mdash;General characters and subdivisions of
+the Trias of the Continent of Europe and Britain&mdash;Trias of
+North America&mdash;Life of the period &mdash; Plants &mdash;
+Echinoderms &mdash; Crustaceans &mdash; Polyzoa &mdash;
+Brachiopods &mdash; Bivalves &mdash; Univalves &mdash; Cephalopods
+&mdash; Intermixture of Palæozoic with Mesozoic types of
+Molluscs &mdash; Fishes &mdash; Amphibians &mdash; Reptiles &mdash;
+Supposed footprints of Birds &mdash; Mammals &mdash; Literature.
+</p>
+
+<p class="center">
+<a href="#page_226">
+CHAPTER XVI.</a>
+</p>
+
+<p class="contents">
+The Jurassic period&mdash;General sequence and subdivisions of the
+Jurassic deposits in Britain&mdash;Jurassic rocks of North
+America&mdash;Life of the period &mdash; Plants &mdash; Corals
+&mdash; Echinoderms &mdash; Crustaceans &mdash; Insects &mdash;
+Brachiopods &mdash; Bivalves &mdash; Univalves &mdash; Pteropods
+&mdash; Tetrabranchiate Cephalopods &mdash; Dibranchiate
+Cephalopods &mdash; Fishes &mdash; Reptiles &mdash; Birds &mdash;
+Mammals &mdash; Literature.
+</p>
+
+<p class="center">
+<a href="#page_256">
+CHAPTER XVII.</a>
+</p>
+
+<p class="contents">
+The Cretaceous period&mdash;General succession and subdivisions
+of the Cretaceous rocks in Britain&mdash;Cretaceous rocks of North
+America&mdash;Life of the period &mdash; Plants &mdash; Protozoa
+&mdash; Corals &mdash; Echinoderms &mdash; Crustaceans &mdash;
+Polyzoa &mdash; Brachiopods &mdash; Bivalves &mdash; Univalves
+&mdash; Tetrabranchiate and Dibranchiate Cephalopods &mdash; Fishes
+&mdash; Reptiles &mdash; Birds &mdash; Literature.
+</p>
+
+<p class="center">
+<a href="#page_284">
+CHAPTER XVIII.</a>
+</p>
+
+<p class="contents">
+The Eocene period&mdash;Relations between the Kainozoic and Mesozoic
+rocks in Europe and in North America&mdash;Classification of the
+Tertiary deposits&mdash;The sequence and subdivisions of the Eocene
+rocks of Britain and France&mdash;Eocene strata of the United
+States&mdash;Life of the period &mdash; Plants &mdash; Foraminifera
+&mdash; Corals &mdash; Echinoderms &mdash; Mollusca &mdash; Fishes
+&mdash; Reptiles &mdash; Birds &mdash; Mammals.
+</p>
+
+<p class="center">
+<a name="page_xiii"><span class="page">Page xiii</span></a>
+<a href="#page_305">
+CHAPTER XIX.</a>
+</p>
+
+<p class="contents">
+The Miocene period&mdash;Miocene strata of Britain&mdash;Of
+France&mdash;Of Belgium&mdash;Of Austria&mdash;Of Switzerland&mdash;Of
+Germany&mdash;Of Greece&mdash;Of India&mdash;Of North America&mdash;Of
+the Arctic regions&mdash;Life of the period&mdash;Vegetation of the
+Miocene period &mdash; Foraminifera &mdash; Corals &mdash; Echinoderms
+&mdash; Articulates &mdash; Mollusca &mdash; Fishes &mdash; Amphibians
+&mdash; Reptiles &mdash; Mammals.
+</p>
+
+<p class="center">
+<a href="#page_323">
+CHAPTER XX.</a>
+</p>
+
+<p class="contents">
+The Pliocene period&mdash;Pliocene deposits of Britain&mdash;Of
+Europe&mdash;Of North America&mdash;Life of the period&mdash;Climate
+of the period as indicated by the Invertebrate animals&mdash;The
+Pliocene Mammalia&mdash;Literature relating to the Tertiary deposits
+and their fossils.
+</p>
+
+<p class="center">
+<a href="#page_334">
+CHAPTER XXI.</a>
+</p>
+
+<p class="contents">
+The Post-Pliocene period&mdash;Division of the Quaternary deposits
+into Post-Pliocene and Recent&mdash;Relations of the Post-Pliocene
+deposits of the northern hemisphere to the "Glacial
+period"&mdash;Pre-Glacial deposits&mdash;Glacial
+deposits&mdash;Arctic Mollusca in Glacial beds&mdash;Post-Glacial
+deposits&mdash;Nature and mode of formation of high-level and
+low-level gravels&mdash;Nature and mode of formation of
+cavern-deposits&mdash;Kent's Cavern-Post&mdash;Pliocene deposits of
+the southern hemisphere.
+</p>
+
+<p class="center">
+<a href="#page_344">
+CHAPTER XXII.</a>
+</p>
+
+<p class="contents">
+Life of the Post-Pliocene period&mdash;Effect of the coming on and
+departure of the Glacial period upon the animals inhabiting the
+northern hemisphere&mdash;Birds of the Post-Pliocene&mdash;Mammalia
+of the Post-Pliocene&mdash;Climate of the Post-Glacial period as
+deduced from the Post-Glacial Mammals&mdash;Occurrence of the bones
+and implements of Man in Post-Pliocene deposits in association with
+the remains of extinct Mammalia&mdash;Literature relating to the
+Post-Pliocene period.
+</p>
+
+<p class="center">
+<a href="#page_367">
+CHAPTER XXIII.</a>
+</p>
+
+<p class="contents">
+The succession of life upon the globe&mdash;Gradual and successive
+introduction of life-forms&mdash;What is meant by "lower" and
+"higher" groups of animals and plants&mdash;Succession in time of
+the great groups of animals in the main corresponding with their
+zoological order&mdash;Identical phenomena in the vegetable
+kingdom&mdash;Persistent types of life&mdash;High organisation of
+many early forms&mdash;Bearings of Palæontology on the
+general doctrine of Evolution.
+</p>
+
+<p class="contents">
+<a href="#page_375">
+APPENDIX.</a>&mdash;Tabular view of the chief Divisions of the
+Animal Kingdom.
+</p>
+
+<p class="contents">
+<a href="#page_379">
+GLOSSARY.</a>
+</p>
+
+<p class="contents">
+<a href="#page_396">
+INDEX.</a>
+</p>
+
+<h2>
+<a name="page_xv"><span class="page">Page xv</span></a>
+LIST OF ILLUSTRATIONS.</h2>
+
+<hr />
+
+<table summary="" style="">
+<tr><td valign="top" class="right">FIG.</td><td>
+&nbsp;
+</td></tr>
+
+<tr><td valign="top" class="right">1.</td><td>
+Cast of <i>Trigonia longa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">2.</td><td>
+Microscopic section of the wood of a fossil Conifer.
+</td></tr>
+
+<tr><td valign="top" class="right">3.</td><td>
+Microscopic section of the wood of the Larch.
+</td></tr>
+
+<tr><td valign="top" class="right">4.</td><td>
+Section of Carboniferous strata, Kinghorn, Fife.
+</td></tr>
+
+<tr><td valign="top" class="right">5.</td><td>
+Diagram illustrating the formation of stratified deposits.
+</td></tr>
+
+<tr><td valign="top" class="right">6.</td><td>
+Microscopic section of a calcareous breccia.
+</td></tr>
+
+<tr><td valign="top" class="right">7.</td><td>
+Microscopic section of White Chalk.
+</td></tr>
+
+<tr><td valign="top" class="right">8.</td><td>
+Organisms in Atlantic Ooze.
+</td></tr>
+
+<tr><td valign="top" class="right">9.</td><td>
+Crinoidal marble.
+</td></tr>
+
+<tr><td valign="top" class="right">10.</td><td>
+Piece of Nummulitic limestone, Pyramids.
+</td></tr>
+
+<tr><td valign="top" class="right">11.</td><td>
+Microscopic section of Foraminiferal
+limestone&mdash;Carboniferous, America.
+</td></tr>
+
+<tr><td valign="top" class="right">12.</td><td>
+Microscopic section of Lower Silurian limestone.
+</td></tr>
+
+<tr><td valign="top" class="right">13.</td><td>
+Microscopic section of oolitic limestone, Jurassic.
+</td></tr>
+
+<tr><td valign="top" class="right">14.</td><td>
+Microscopic section of oolitic limestone, Carboniferous.
+</td></tr>
+
+<tr><td valign="top" class="right">15.</td><td>
+Organisms in Barbadoes earth.
+</td></tr>
+
+<tr><td valign="top" class="right">15.</td><td>
+Organisms in Barbadoes earth.
+</td></tr>
+
+<tr><td valign="top" class="right">16.</td><td>
+Organisms in Richmond earth.
+</td></tr>
+
+<tr><td valign="top" class="right">17.</td><td>
+Ideal section of the crust of the earth.
+</td></tr>
+
+<tr><td valign="top" class="right">18.</td><td>
+Unconformable junction of Chalk and Eocene rocks.
+</td></tr>
+
+<tr><td valign="top" class="right">19.</td><td>
+Erect trunk of a <i>Sigillaria</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">20.</td><td>
+Diagrammatic section of the Laurentian rocks
+</td></tr>
+
+<tr><td valign="top" class="right">21.</td><td>
+Microscopic section of Laurentian limestone.
+</td></tr>
+
+<tr><td valign="top" class="right">22.</td><td>
+Fragment of a mass of <i>Eozoön Canadense</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">23.</td><td>
+Diagram illustrating the structure of <i>Eozoön</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">24.</td><td>
+Microscopic section of <i>Eozoön Canadense</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">25.</td><td>
+<i>Nonionina</i> and <i>Gromia</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">26.</td><td>
+Group of shells of living <i>Foraminifera</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">27.</td><td>
+Diagrammatic section of Cambrian strata.
+</td></tr>
+
+<tr><td valign="top" class="right">28.</td><td>
+<i>Eophyton Linneanum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">29.</td><td>
+<i>Oldhamia antiqua</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">30.</td><td>
+<i>Scolithus Canadensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">31.</td><td>
+Group of Cambrian Trilobites.
+</td></tr>
+
+<tr><td valign="top" class="right">32.</td><td>
+Group of characteristic Cambrian fossils.
+</td></tr>
+
+<tr><td valign="top" class="right">33.</td><td>
+Fragment of <i>Dictyonema sociale</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">34.</td><td>
+Generalised section of the Lower Silurian rocks
+of Wales.
+</td></tr>
+
+<tr><td valign="top" class="right">35.</td><td>
+Generalised section of the Lower Silurian rocks
+of North America.
+</td></tr>
+
+<tr><td valign="top" class="right">36.</td><td>
+<i>Licrophycus Ottawaensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">37.</td><td>
+<i>Astylospongia prœmorsa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">38.</td><td>
+<i>Stromatopora rugosa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">39.</td><td>
+<i>Dichograptus octobrachiatus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">40.</td><td>
+<i>Didymograptus divaricatus</i>.
+<a name="page_xvi"><span class="page">Page xvi</span></a>
+</td></tr>
+
+<tr><td valign="top" class="right">41.</td><td>
+<i>Diplograptus pristis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">42.</td><td>
+<i>Phyllograptus typus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">43.</td><td>
+<i>Zaphrentis Stokesi</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">44.</td><td>
+<i>Strombodes pentagonus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">45.</td><td>
+<i>Columnaria alveolata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">46.</td><td>
+Group of Cystideans.
+</td></tr>
+
+<tr><td valign="top" class="right">47.</td><td>
+Group of Lower Silurian Crustaceans.
+</td></tr>
+
+<tr><td valign="top" class="right">48.</td><td>
+<i>Ptilodictya falciformis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">49.</td><td>
+<i>Ptilodictya Schafferi</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">50.</td><td>
+Group of Lower Silurian Brachiopods.
+</td></tr>
+
+<tr><td valign="top" class="right">51.</td><td>
+Group of Lower Silurian Brachiopods.
+</td></tr>
+
+<tr><td valign="top" class="right">52.</td><td>
+<i>Murchisonia gracilis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">53.</td><td>
+<i>Bellerophon argo</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">54.</td><td>
+<i>Maclurea crenulata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">55.</td><td>
+<i>Orthoceras crebriseptum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">56.</td><td>
+Restoration of <i>Orthoceras</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">57.</td><td>
+Generalised section of the Upper Silurian rocks.
+</td></tr>
+
+<tr><td valign="top" class="right">58.</td><td>
+<i>Monograptus priodon</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">59.</td><td>
+<i>Halysites catenularia</i> and <i>H. agglomerata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">60.</td><td>
+Group of Upper Silurian Star-fishes.
+</td></tr>
+
+<tr><td valign="top" class="right">61.</td><td>
+<i>Protaster Sedgwickii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">62.</td><td>
+Group of Upper Silurian Crinoids.
+</td></tr>
+
+<tr><td valign="top" class="right">63.</td><td>
+<i>Planolites vulgaris</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">64.</td><td>
+Group of Upper Silurian Trilobites.
+</td></tr>
+
+<tr><td valign="top" class="right">65.</td><td>
+<i>Pterygotus Anglicus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">66.</td><td>
+Group of Upper Silurian <i>Polyzoa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">67.</td><td>
+<i>Spirifera hysterica</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">68.</td><td>
+Group of Upper Silurian Brachiopods.
+</td></tr>
+
+<tr><td valign="top" class="right">69.</td><td>
+Group of Upper Silurian Brachiopods.
+</td></tr>
+
+<tr><td valign="top" class="right">70.</td><td>
+<i>Pentamerus Knightii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">71.</td><td>
+<i>Cardiola interrupta, C. fibrosa</i>, and
+<i>Pterinœa subfalcata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">72.</td><td>
+Group of Upper Silurian Univalves.
+</td></tr>
+
+<tr><td valign="top" class="right">73.</td><td>
+<i>Tentaculites ornatus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">74.</td><td>
+<i>Pteraspis Banksii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">75.</td><td>
+<i>Onchus tenuistriatus</i> and <i>Thelodus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">76.</td><td>
+Generalised section of the Devonian rocks of North America.
+</td></tr>
+
+<tr><td valign="top" class="right">77.</td><td>
+<i>Psilophyton princeps</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">78.</td><td>
+<i>Prototaxites Logani</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">79.</td><td>
+<i>Stromatopora tuberculata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">80.</td><td>
+<i>Cystiphyllum vesiculosum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">81.</td><td>
+<i>Zaphrentis cornicula</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">82.</td><td>
+<i>Heliophyllum exiguum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">83.</td><td>
+<i>Crepidophyllum Archiaci</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">84.</td><td>
+<i>Favosites Gothlandica</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">85.</td><td>
+<i>Favosites hemisphœrica</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">86.</td><td>
+<i>Spirorbis omphalodes</i> and <i>S. Arkonensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">87.</td><td>
+<i>Spirorbis laxus</i> and <i>S. Spinulifera</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">88.</td><td>
+Group of Devonian Trilobites.
+</td></tr>
+
+<tr><td valign="top" class="right">89.</td><td>
+Wing of <i>Platephemera antiqua</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">90.</td><td>
+<i>Clathropora intertexta</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">91.</td><td>
+<i>Ceriopora Hamiltonensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">92.</td><td>
+<i>Fenestella magnifica</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">93.</td><td>
+<i>Retepora Phillipsi</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">94.</td><td>
+<i>Fenestella cribrosa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">95.</td><td>
+<i>Spirifera sculptilis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">96.</td><td>
+<i>Spirifera mucronata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">97.</td><td>
+<i>Atrypa reticularis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">98.</td><td>
+<i>Strophomena rhomboidalis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">99.</td><td>
+<i>Platyceras dumosum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">100.</td><td>
+<i>Conularia ornata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">101.</td><td>
+<i>Clymenia Sedgwickii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">102.</td><td>
+Group of Fishes from the Devonian rocks of North America.
+</td></tr>
+
+<tr><td valign="top" class="right">103.</td><td>
+<i>Cephalaspis Lyellii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">104.</td><td>
+<i>Pterichthys cornutus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">105.</td><td>
+<i>Polypterus</i> and <i>Osteolepis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">106.</td><td>
+<i>Holoptychius nobilissimus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">107.</td><td>
+Generalised section of the Carboniferous rocks of the
+North of England.
+</td></tr>
+
+<tr><td valign="top" class="right">108.</td><td>
+<i>Odontopteris Schlotheimii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">109.</td><td>
+<i>Calamites cannœformis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">110.</td><td>
+<i>Lepidodendron Sternbergii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">111.</td><td>
+<i>Sigillaria Grœseri</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">112.</td><td>
+<i>Stigmaria ficoides</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">113.</td><td>
+<i>Trigonocarpum ovatum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">114.</td><td>
+Microscopic section of Foraminiferal
+limestone&mdash;Carboniferous, North America.
+</td></tr>
+
+<tr><td valign="top" class="right">115.</td><td>
+<i>Fusulina cylindrica</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">116.</td><td>
+Group of Carboniferous Corals.
+</td></tr>
+
+<tr><td valign="top" class="right">117.</td><td>
+<i>Platycrinus tricontadactylus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">118.</td><td>
+<i>Pentremites pyriformis</i> and <i>P. conoideus</i>.
+<a name="page_xvii"><span class="page">Page xvii</span></a>
+</td></tr>
+
+<tr><td valign="top" class="right">119.</td><td>
+<i>Archœocidaris ellipticus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">120.</td><td>
+<i>Spirorbis Carbonarius</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">121.</td><td>
+<i>Prestwichia rotundata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">122.</td><td>
+Group of Carboniferous Crustaceans.
+</td></tr>
+
+<tr><td valign="top" class="right">123.</td><td>
+<i>Cyclophthalmus senior</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">124.</td><td>
+<i>Xylobius Sigillariœ</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">125.</td><td>
+<i>Haplophlebium Barnesi</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">126.</td><td>
+Group of Carboniferous <i>Polyzoa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">127.</td><td>
+Group of Carboniferous <i>Brachiopoda</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">128.</td><td>
+<i>Pupa vetusta</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">129.</td><td>
+<i>Goniatites Fossœ</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">130.</td><td>
+<i>Amblypterus macropterus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">131.</td><td>
+<i>Cochliodus contortus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">132.</td><td>
+<i>Anthracosaurus Russelli</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">133.</td><td>
+Generalised section of the Permian rocks.
+</td></tr>
+
+<tr><td valign="top" class="right">134.</td><td>
+<i>Walchia piniformis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">135.</td><td>
+Group of Permian <i>Brachiopods</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">136.</td><td>
+<i>Arca antiqua</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">137.</td><td>
+<i>Platysomus gibbosus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">138.</td><td>
+<i>Protorosaurus Speneri</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">139.</td><td>
+Generalised section of the Triassic rocks.
+</td></tr>
+
+<tr><td valign="top" class="right">140.</td><td>
+<i>Zamia spiralis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">141.</td><td>
+Triassic Conifers and Cycads.
+</td></tr>
+
+<tr><td valign="top" class="right">142.</td><td>
+<i>Encrinus liliiformis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">143.</td><td>
+<i>Aspidura loricata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">144.</td><td>
+Group of Triassic Bivalves.
+</td></tr>
+
+<tr><td valign="top" class="right">145.</td><td>
+<i>Ceratites nodosus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">146.</td><td>
+Tooth of <i>Ceratodus serratus</i> and <i>C. Altus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">147.</td><td>
+<i>Ceratodus Fosteri</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">148.</td><td>
+Footprints of <i>Cheirotherium</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">149.</td><td>
+Section of tooth of <i>Labyrinthodont</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">150.</td><td>
+Skull of <i>Mastodonsaurus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">151.</td><td>
+Skull of <i>Rhynchosaurus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">152.</td><td>
+<i>Belodon</i>, <i>Nothosaurus</i>,
+<i>Palœosaurus</i>, &amp;c.
+</td></tr>
+
+<tr><td valign="top" class="right">153.</td><td>
+<i>Placodus gigas</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">154.</td><td>
+Skulls of <i>Dicynodon</i> and <i>Oudenodon</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">155.</td><td>
+Supposed footprint of Bird, from the Trias of Connecticut.
+</td></tr>
+
+<tr><td valign="top" class="right">156.</td><td>
+Lower jaw of <i>Dromatherium sylvestre</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">157.</td><td>
+Molar tooth of <i>Microlestes antiquus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">158.</td><td>
+<i>Myrmecobius fasciatus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">159.</td><td>
+Generalised section of the Jurassic rocks.
+</td></tr>
+
+<tr><td valign="top" class="right">160.</td><td>
+<i>Mantellia megalophylla</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">161.</td><td>
+<i>Thecosmilia annularis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">162.</td><td>
+<i>Pentacrinus fasciculosus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">163.</td><td>
+<i>Hemicidaris crenularis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">164.</td><td>
+<i>Eryon arctiformis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">165.</td><td>
+Group of Jurassic Brachiopods.
+</td></tr>
+
+<tr><td valign="top" class="right">166.</td><td>
+<i>Ostrea Marshii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">167.</td><td>
+<i>Gryphœa incurva</i>
+</td></tr>
+
+<tr><td valign="top" class="right">168.</td><td>
+<i>Diceras arietina</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">169.</td><td>
+<i>Nerinœa Goodhallii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">170.</td><td>
+<i>Ammonites Humphresianus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">171.</td><td>
+<i>Ammonites bifrons</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">172.</td><td>
+<i>Beloteuthis subcostata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">173.</td><td>
+Belemnite restored; diagram of Belemnite; <i>Belemnites
+canaliculata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">174.</td><td>
+<i>Tetragonolepis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">175.</td><td>
+<i>Acrodus nobilis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">176.</td><td>
+<i>Ichthyosaurus communis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">177.</td><td>
+<i>Plesiosaurus dolichodeirus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">178.</td><td>
+<i>Pterodactylus crassirostris</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">179.</td><td>
+<i>Ramphorhynchus Bucklandi</i>, restored.
+</td></tr>
+
+<tr><td valign="top" class="right">180.</td><td>
+Skull of <i>Megalosaurus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">181.</td><td>
+<i>Archœopteryx macrura</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">182.</td><td>
+<i>Archœopteryx, restored</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">183.</td><td>
+Jaw of <i>Amphitherium Prevostii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">184.</td><td>
+Jaws of Oolitic Mammals.
+</td></tr>
+
+<tr><td valign="top" class="right">185.</td><td>
+Generalised section of the Cretaceous rocks.
+</td></tr>
+
+<tr><td valign="top" class="right">186.</td><td>
+Cretaceous Angiosperms.
+</td></tr>
+
+<tr><td valign="top" class="right">187.</td><td>
+<i>Rotalia Boueana</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">188.</td><td>
+<i>Siphonia ficus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">189.</td><td>
+<i>Ventriculites simplex</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">190.</td><td>
+<i>Synhelia Sharpeana</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">191.</td><td>
+<i>Galerites albogalerus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">192.</td><td>
+<i>Discoidea cylindrica</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">193.</td><td>
+<i>Escharina Oceani</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">194.</td><td>
+<i>Terebratella Astieriana</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">195.</td><td>
+<i>Crania Ignabergensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">196.</td><td>
+<i>Ostrea Couloni</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">197.</td><td>
+<i>Spondylus spinosus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">198.</td><td>
+<i>Inoceramus sulcatus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">199.</td><td>
+<i>Hippurites Toucasiana</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">200.</td><td>
+<i>Voluta elongata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">201.</td><td>
+<i>Nautilus Danicus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">202.</td><td>
+<i>Ancyloceras Matheronianus</i>.
+<a name="page_xviii"><span class="page">Page xviii</span></a>
+</td></tr>
+
+<tr><td valign="top" class="right">203.</td><td>
+<i>Turrilites catenatus</i>
+</td></tr>
+
+<tr><td valign="top" class="right">204.</td><td>
+Forms of Cretaceous <i>Ammonitidœ</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">205.</td><td>
+<i>Belemnitella mucronata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">206.</td><td>
+Tooth of <i>Hybodus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">207.</td><td>
+Fin-spine of <i>Hybodus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">208.</td><td>
+<i>Beryx Lewesiensis</i> and <i>Osmeroides Mantelli</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">209.</td><td>
+Teeth of <i>Iguanodon</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">210.</td><td>
+Skull of <i>Mosasaurus Camperi</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">211.</td><td>
+<i>Chelone Benstedi</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">212.</td><td>
+Jaws and vertebræ of <i>Odontornithes</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">213.</td><td>
+Fruit of <i>Nipadites</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">214.</td><td>
+<i>Nummulina lœvigata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">215.</td><td>
+<i>Turbinolia sulcata</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">216.</td><td>
+<i>Cardita planicosta</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">217.</td><td>
+<i>Typhis tubifer</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">218.</td><td>
+<i>Cyprœa elegans</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">219.</td><td>
+<i>Cerithium hexagonum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">220.</td><td>
+<i>Limnœa pyramidalis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">221.</td><td>
+<i>Physa columnaris</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">222.</td><td>
+<i>Cyclostoma Arnoudii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">223.</td><td>
+<i>Rhombus minimus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">224.</td><td>
+<i>Otodus obliquus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">225.</td><td>
+<i>Myliobatis Edwardsii</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">226.</td><td>
+Upper jaw of Alligator.
+</td></tr>
+
+<tr><td valign="top" class="right">227.</td><td>
+Skull of <i>Odontopteryx toliapicus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">228.</td><td>
+<i>Zeuglodon cetoides</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">229.</td><td>
+<i>Palœotherium magnum</i>, restored.
+</td></tr>
+
+<tr><td valign="top" class="right">230.</td><td>
+Feet of <i>Equidœ</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">231.</td><td>
+<i>Anoplothelium commune</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">232.</td><td>
+Skull of <i>Dinoceras mirabilis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">233.</td><td>
+<i>Vespertilio Parisiensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">234.</td><td>
+Miocene Palms.
+</td></tr>
+
+<tr><td valign="top" class="right">235.</td><td>
+<i>Platanus aceroides</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">236.</td><td>
+<i>Cinnamomum polymorphum</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">237.</td><td>
+<i>Textularia Meyeriana</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">238.</td><td>
+<i>Scutella subrotunda</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">239.</td><td>
+<i>Hyalea Orbignyana</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">240.</td><td>
+Tooth of <i>Oxyrhina</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">241.</td><td>
+Tooth of <i>Carcharodon</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">242.</td><td>
+<i>Andrias Scheuchzeri</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">243.</td><td>
+Skull of <i>Brontotherium ingens</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">244.</td><td>
+<i>Hippopotamus Sivalensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">245.</td><td>
+Skull of <i>Sivatherium</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">246.</td><td>
+Skull of <i>Deinotherium</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">247.</td><td>
+Tooth of <i>Elephas planfrons</i> and of <i>Mastodon
+Sivalensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">248.</td><td>
+Jaw of <i>Pliopithecus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">249.</td><td>
+<i>Rhinoceros Etruscus</i> and <i>R. megarhinus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">250.</td><td>
+Molar tooth of <i>Mastodon Arvernensis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">251.</td><td>
+Molar tooth of <i>Etephas meridionalis</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">252.</td><td>
+Molar tooth of <i>Elephas antiquus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">253.</td><td>
+Skull and tooth of <i>Machairodus cultridens</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">254.</td><td>
+<i>Pecten Islandicus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">255.</td><td>
+Diagram of high-level and low-level gravels.
+</td></tr>
+
+<tr><td valign="top" class="right">256.</td><td>
+Diagrammatic section of Cave.
+</td></tr>
+
+<tr><td valign="top" class="right">257.</td><td>
+<i>Dinornis elephantopus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">258.</td><td>
+Skull of <i>Diprotodon</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">259.</td><td>
+Skull of <i>Thylacoleo</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">260.</td><td>
+Skeleton of <i>Megatherium</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">261.</td><td>
+Skeleton of <i>Mylodon</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">262.</td><td>
+<i>Glyptodon clavipes</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">263.</td><td>
+Skull of <i>Rhinoceros tichorhinus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">264.</td><td>
+Skeleton of <i>Cervus megaceros</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">265.</td><td>
+Skull of <i>Bos primigenius</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">266.</td><td>
+Skeleton of Mammoth.
+</td></tr>
+
+<tr><td valign="top" class="right">267.</td><td>
+Molar tooth of Mammoth.
+</td></tr>
+
+<tr><td valign="top" class="right">268.</td><td>
+Skull of <i>Ursus spelœus</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">269.</td><td>
+Skull of <i>Hyœna spelœa</i>.
+</td></tr>
+
+<tr><td valign="top" class="right">270.</td><td>
+Lower jaw of <i>Trogontherium Cuvieri</i>.
+</td></tr>
+
+</table>
+
+<h2>
+<a name="page_xix"><span class="page">Page xix</span></a>
+PART I.
+</h2>
+
+<hr />
+
+<p class="part">
+PRINCIPLES OF PALÆONTOLOGY.
+</p>
+
+<h2>
+<a name="page_1"><span class="page">Page 1</span></a>
+<span class="smaller">THE</span><br/>
+ANCIENT LIFE-HISTORY<br/>
+<span class="smaller">OF</span><br/>
+THE EARTH
+</h2>
+
+<hr />
+
+<h3>INTRODUCTION.</h3>
+
+<p class="subtitle">
+THE LAWS OF GEOLOGICAL ACTION.
+</p>
+
+<p class="indent">
+Under the general title of "Geology" are usually included at
+least two distinct branches of inquiry, allied to one another in
+the closest manner, and yet so distinct as to be largely capable
+of separate study. <i>Geology</i>,[1] in its strict sense, is
+the science which is concerned with the investigation of the
+materials which compose the earth, the methods in which those
+materials have been arranged, and the causes and modes of origin
+of these arrangements. In this limited aspect, Geology is nothing
+more than the Physical Geography of the past, just as Physical
+Geography is the Geology of to-day; and though it has to call in
+the aid of Physics, Astronomy, Mineralogy, Chemistry, and other
+allies more remote, it is in itself a perfectly distinct and
+individual study. One has, however, only to cross the threshold
+of Geology to discover that the field and scope of the science
+cannot be thus rigidly limited to purely physical problems. The
+study of the physical development of the earth throughout past
+ages brings us at once in contact with the forms of animal and
+vegetable life which peopled its surface in bygone epochs, and it
+is found impossible adequately to comprehend
+<a name="page_2"><span class="page">Page 2</span></a>
+the former, unless we possess some knowledge of the latter.
+However great its physical advances may be, Geology remains
+imperfect till it is wedded with Palæontology,[2] a study
+which essentially belongs to the vast complex of the Biological
+Sciences, but at the same time has its strictly geological side.
+Dealing, as it does, wholly with the consideration of such living
+beings as do not belong exclusively to the present order of
+things, Palæontology is, in reality, a branch of Natural
+History, and may be regarded as substantially the Zoology and
+Botany of the past. It is the ancient life-history of the earth,
+as revealed to us by the labours of palæontologists, with
+which we have mainly to do here; but before entering upon this,
+there are some general questions, affecting Geology and
+Palæontology alike, which may be very briefly discussed.
+</p>
+
+<p class="footnote">
+[Footnote 1: Gr. <i>ge</i>, the earth; <i>logos</i>, a discourse.]
+</p>
+
+<p class="footnote">
+[Footnote 2: Gr. <i>palaios</i>, ancient; <i>onta</i>, beings;
+<i>logos</i>, discourse.]
+</p>
+
+<p class="indent">
+The working geologist, dealing in the main with purely physical
+problems, has for his object to determine the material structure
+of the earth, and to investigate, as far as may be, the long chain
+of causes of which that structure is the ultimate result. No wider
+or more extended field of inquiry could be found; but philosophical
+geology is not content with this. At all the confines of his
+science, the transcendental geologist finds himself confronted
+with some of the most stupendous problems which have ever engaged
+the restless intellect of humanity. The origin and primæval
+constitution of the terrestrial globe, the laws of geologic action
+through long ages of vicissitude and development, the origin of
+life, the nature and source of the myriad complexities of living
+beings, the advent of man, possibly even the future history of
+the earth, are amongst the questions with which the geologist
+has to grapple in his higher capacity.
+</p>
+
+<p class="indent">
+These are problems which have occupied the attention of philosophers
+in every age of the world, and in periods long antecedent to
+the existence of a science of geology. The mere existence of
+cosmogonies in the religion of almost every nation, both ancient
+and modern, is a sufficient proof of the eager desire of the
+human mind to know something of the origin of the earth on which
+we tread. Every human being who has gazed on the vast panorama
+of the universe, though it may have been but with the eyes of
+a child, has felt the longing to solve, however imperfectly,
+"the riddle of the painful earth," and has, consciously or
+unconsciously, elaborated some sort of a theory as to the why and
+wherefore of what he sees. Apart from the profound and perhaps
+inscrutable problems which lie at the bottom of human existence,
+men have in all ages invented
+<a name="page_3"><span class="page">Page 3</span></a>
+theories to explain the common phenomena of the material universe;
+and most of these theories, however varied in their details, turn
+out on examination to have a common root, and to be based on the
+same elements. Modern geology has its own theories on the same
+subject, and it will be well to glance for a moment at the
+principles underlying the old and the new views.
+</p>
+
+<p class="indent">
+It has been maintained, as a metaphysical hypothesis, that there
+exists in the mind of man an inherent principle, in virtue of
+which he believes and expects that what has been, will be; and
+that the course of nature will be a continuous and uninterrupted
+one. So far, however, from any such belief existing as a necessary
+consequence of the constitution of the human mind, the real fact
+seems to be that the contrary belief has been almost universally
+prevalent. In all old religions, and in the philosophical systems
+of almost all ancient nations, the order of the universe has
+been regarded as distinctly unstable, mutable, and temporary.
+A beginning and an end have always been assumed, and the course
+of terrestrial events between these two indefinite points has
+been regarded as liable to constant interruption by revolutions
+and catastrophes of different kinds, in many cases emanating from
+supernatural sources. Few of the more ancient theological creeds,
+and still fewer of the ancient philosophies, attained body and
+shape without containing, in some form or another, the belief
+in the existence of periodical convulsions, and of alternating
+cycles of destruction and repair.
+</p>
+
+<p class="indent">
+That geology, in its early infancy, should have become imbued
+with the spirit of this belief, is no more than might have been
+expected; and hence arose the at one time powerful and
+generally-accepted doctrine of "Catastrophism." That the succession
+of phenomena upon the globe, whereby the earth's crust had assumed
+the configuration and composition which we find it to possess,
+had been a discontinuous and broken succession, was the almost
+inevitable conclusion of the older geologists. Everywhere in
+their study of the rocks they met with apparently impassable
+gaps, and breaches of continuity that could not be bridged over.
+Everywhere they found themselves conducted abruptly from one system
+of deposits to others totally different in mineral character or
+in stratigraphical position. Everywhere they discovered that
+well-marked and easily recognisable groups of animals and plants
+were succeeded, without the intermediation of any obvious lapse
+of time, by other assemblages of organic beings of a different
+character. Everywhere they found evidence that the earth's crust
+<a name="page_4"><span class="page">Page 4</span></a>
+had undergone changes of such magnitude as to
+render it seemingly irrational to suppose that they could have
+been produced by any process now in existence. If we add to the
+above the prevalent belief of the time as to the comparative
+brevity of the period which had elapsed since the birth of the
+globe, we can readily understand the general acceptance of some
+form of catastrophism amongst the earlier geologists.
+</p>
+
+<p class="indent">
+As regards its general sense and substance, the doctrine of
+catastrophism held that the history of the earth, since first
+it emerged from the primitive chaos, had been one of periods
+of repose, alternating with catastrophes and cataclysms of a
+more or less violent character. The periods of tranquillity were
+supposed to have been long and protracted; and during each of them
+it was thought that one of the great geological "formations" was
+deposited. In each of these periods, therefore, the condition of the
+earth was supposed to be much the same as it is now&mdash;sediment
+was quietly accumulated at the bottom of the sea, and animals and
+plants flourished uninterruptedly in successive generations.
+Each period of tranquillity, however, was believed to have been,
+sooner or later, put an end to by a sudden and awful convulsion
+of nature, ushering in a brief and paroxysmal period, in which
+the great physical forces were unchained and permitted to spring
+into a portentous activity. The forces of subterranean fire,
+with their concomitant phenomena of earthquake and volcano, were
+chiefly relied upon as the efficient causes of these periods of
+spasm and revolution. Enormous elevations of portions of the
+earth's crust were thus believed to be produced, accompanied by
+corresponding and equally gigantic depressions of other portions.
+In this way new ranges of mountains were produced, and previously
+existing ranges levelled with the ground, seas were converted into
+dry land, and continents buried beneath the ocean&mdash;catastrophe
+following catastrophe, till the earth was rendered uninhabitable,
+and its races of animals and plants were extinguished, never to
+reappear in the same form. Finally, it was believed that this
+feverish activity ultimately died out, and that the ancient peace
+once more came to reign upon the earth. As the abnormal throes
+and convulsions began to be relieved, the dry land and sea once
+more resumed their relations of stability, the conditions of
+life were once more established, and new races of animals and
+plants sprang into existence, to last until the supervention
+of another fever-fit.
+</p>
+
+<p class="indent">
+Such is the past history of the globe, as sketched for us, in
+alternating scenes of fruitful peace and revolutionary destruction,
+by the earlier geologists. As before said, we cannot
+<a name="page_5"><span class="page">Page 5</span></a>
+wonder at the former general acceptance of Catastrophistic
+doctrines. Even in the light of our present widely-increased
+knowledge, the series of geological monuments remains a broken
+and imperfect one; nor can we ever hope to fill up completely
+the numerous gaps with which the geological record is defaced.
+Catastrophism was the natural method of accounting for these gaps,
+and, as we shall see, it possesses a basis of truth. At present,
+however, catastrophism may be said to be nearly extinct, and its
+place is taken by the modern doctrine of "Continuity" or
+"Uniformity"&mdash;a doctrine with which the name of Lyell must
+ever remain imperishably associated.
+</p>
+
+<p class="indent">
+The fundamental thesis of the doctrine of Uniformity is, that,
+in spite of all apparent violations of continuity, the sequence
+of geological phenomena has in reality been a regular and
+uninterrupted one; and that the vast changes which can be shown
+to have passed over the earth in former periods have been the
+result of the slow and ceaseless working of the ordinary physical
+forces&mdash;acting with no greater intensity than they do now, but
+acting through enormously prolonged periods. The essential element
+in the theory of Continuity is to be found in the allotment of
+indefinite time for the accomplishment of the known series of
+geological changes. It is obviously the case, namely, that there
+are two possible explanations of all phenomena which lie so far
+concealed in "the dark backward and abysm of time," that we can
+have no direct knowledge of the manner in which they were produced.
+We may, on the one hand, suppose them to be the result of some
+very powerful cause, acting through a short period of time. That
+is Catastrophism. Or, we may suppose them to be caused by a much
+weaker force operating through a proportionately prolonged period.
+This is the view of the Uniformitarians. It is a question of
+<i>energy</i> versus <i>time</i> and it is <i>time</i> which is
+the true element of the case. An earthquake may remove a mountain
+in the course of a few seconds; but the dropping of the gentle rain
+will do the same, if we extend its operations over a millennium.
+And this is true of all agencies which are now at work, or ever
+have been at work, upon our planet. The Catastrophists, believing
+that the globe is but, as it were, the birth of yesterday, were
+driven of necessity to the conclusion that its history had been
+checkered by the intermittent action of paroxysmal and almost
+inconceivably potent forces. The Uniformitarians, on the other
+hand, maintaining the "adequacy of existing causes," and denying
+that the known physical forces ever acted in past time with greater
+intensity than they do at present, are, equally of necessity,
+driven to the conclusion that
+<a name="page_6"><span class="page">Page 6</span></a>
+the world is
+truly in its "hoary eld," and that its present state is really
+the result of the tranquil and regulated action of known forces
+through unnumbered and innumerable centuries.
+</p>
+
+<p class="indent">
+The most important point for us, in the present connection, is
+the bearing of these opposing doctrines upon the question, as
+to the origin of the existing terrestrial order. On any doctrine
+of uniformity that order has been evolved slowly, and, according
+to law, from a pre-existing order. Any doctrine of catastrophism,
+on the other hand, carries with it, by implication, the belief
+that the present order of things was brought about suddenly and
+irrespective of any pre-existent order; and it is important to
+hold clear ideas as to which of these beliefs is the true one. In
+the first place, we may postulate that the world had a beginning,
+and, equally, that the existing terrestrial order had a beginning.
+However far back we may go, geology does not, and cannot, reach the
+actual beginning of the world; and we are, therefore, left simply
+to our own speculations on this point. With regard, however, to
+the existing terrestrial order, a great deal can be discovered,
+and to do so is one of the principal tasks of geological science.
+The first steps in the production of that order lie buried in
+the profound and unsearchable depths of a past so prolonged as
+to present itself to our finite minds as almost in eternity.
+The last steps are in the prophetic future, and can be but dimly
+guessed at. Between the remote past and the distant future, we
+have, however, a long period which is fairly open to inspection;
+and in saying a "long" period, it is to be borne in mind that
+this term is used in its <i>geological</i> sense. Within this
+period, enormously long as it is when measured by human standards,
+we can trace with reasonable certainty the progressive march
+of events, and can determine the laws of geological action, by
+which the present order of things has been brought about.
+</p>
+
+<p class="indent">
+The natural belief on this subject doubtless is, that the world,
+such as we now see it, possessed its present form and configuration
+from the beginning. Nothing can be more natural than the belief
+that the present continents and oceans have always been where
+they are now; that we have always had the same mountains and
+plains; that our rivers have always had their present courses,
+and our lakes their present positions; that our climate has always
+been the same; and that our animals and plants have always been
+identical with those now familiar to us. Nothing could be more
+natural than such a belief, and nothing could be further removed
+from the actual truth. On the contrary, a very slight acquaintance
+with geology shows us, in the words of Sir John Herschel, that
+<a name="page_7"><span class="page">Page 7</span></a>
+"the actual configuration of our continents
+and islands, the coast-lines of our maps, the direction and
+elevation of our mountain-chains, the courses of our rivers, and
+the soundings of our oceans, are not things primordially arranged
+in the construction of our globe, but results of successive and
+complex actions on a former state of things; <i>that</i>, again,
+of similar actions on another still more remote; and so on, till
+the original and really permanent state is pushed altogether out
+of sight and beyond the reach even of imagination; while on the
+other hand, a similar, and, as far as we can see, interminable
+vista is opened out for the future, by which the habitability
+of our planet is secured amid the total abolition on it of the
+present theatres of terrestrial life."
+</p>
+
+<p class="indent">
+Geology, then, teaches us that the physical features which now
+distinguish the earth's surface have been produced as the ultimate
+result of an almost endless succession of precedent changes.
+Palæontology teaches us, though not yet in such assured
+accents, the same lesson. Our present animals and plants have not
+been produced, in their innumerable forms, each as we now know it,
+as the sudden, collective, and simultaneous birth of a renovated
+world. On the contrary, we have the clearest evidence that some
+of our existing animals and plants made their appearance upon the
+earth at a much earlier period than others. In the confederation
+of animated nature some races can boast of an immemorial antiquity,
+whilst others are comparative <i>parvenus</i>. We have also the
+clearest evidence that the animals and plants which now inhabit the
+globe have been preceded, over and over again, by other different
+assemblages of animals and plants, which have flourished in
+successive periods of the earth's history, have reached their
+culmination, and then have given way to a fresh series of living
+beings. We have, finally, the clearest evidence that these successive
+groups of animals and plants (faunæ and floræ) are to
+a greater or less extent directly connected with one another. Each
+group is, to a greater or less extent, the lineal descendant of
+the group which immediately preceded it in point of time, and is
+more or less fully concerned with giving origin to the group
+which immediately follows it. That this law of "evolution" has
+prevailed to a great extent is quite certain; but it does not
+meet all the exigencies of the case, and it is probable that
+its action has been supplemented by some still unknown law of
+a different character.
+</p>
+
+<p class="indent">
+We shall have to consider the question of geological "continuity"
+again. In the meanwhile, it is sufficient to state that this
+doctrine is now almost universally accepted as the basis
+<a name="page_8"><span class="page">Page 8</span></a>
+of all inquiries, both in the domain of geology and
+that of palæontology. The advocates of continuity possess
+one immense advantage over those who believe in violent and
+revolutionary convulsions, that they call into play only agencies
+of which we have actual knowledge. We <i>know</i> that certain
+forces are now at work, producing certain modifications in the
+present condition of the globe; and we <i>know</i> that these
+forces are capable of producing the vastest of the changes which
+geology brings under our consideration, provided we assign a time
+proportionately vast for their operation. On the other hand, the
+advocates of catastrophism, to make good their views, are
+compelled to invoke forces and actions, both destructive and
+restorative, of which we have, and can have, no direct knowledge.
+They endow the whirlwind and the earthquake, the central fire and
+the rain from heaven, with powers as mighty as ever imagined in
+fable, and they build up the fragments of a repeatedly shattered
+world by the intervention of an intermittently active creative
+power.
+</p>
+
+<p class="indent">
+It should not be forgotten, however, that from one point of view
+there is a truth in catastrophism which is sometimes overlooked
+by the advocates of continuity and uniformity. Catastrophism
+has, as its essential feature, the proposition that the known
+and existing forces of the earth at one time acted with much
+greater intensity and violence than they do at present, and they
+carry down the period of this excessive action to the commencement
+of the present terrestrial order. The Uniformitarians, in effect,
+deny this proposition, at any rate as regards any period of the
+earth's history of which we have actual cognisance. If, however,
+the "nebular hypothesis" of the origin of the universe be well
+founded&mdash;as is generally admitted&mdash;then, beyond question,
+the earth is a gradually cooling body, which has at one time been
+very much hotter than it is at present. There has been a time,
+therefore, in which the igneous forces of the earth, to which we
+owe the phenomena of earthquakes and volcanoes, must have been
+far more intensely active than we can conceive of from anything
+that we can see at the present day. By the same hypothesis, the
+sun is a cooling body, and must at one time have possessed a
+much higher temperature than it has at present. But increased
+heat of the sun would seriously alter the existing conditions
+affecting the evaporation and precipitation of moisture on our
+earth; and hence the aqueous forces may also have acted at one
+time more powerfully than they do now. The fundamental principle
+of catastrophism is, therefore, not wholly vicious; and we have
+reason to think that there must have been periods&mdash;very
+<a name="page_9"><span class="page">Page 9</span></a>
+remote, it is true, and perhaps unrecorded
+in the history of the earth&mdash;in which the known physical
+forces may have acted with an intensity much greater than direct
+observation would lead us to imagine. And this may be believed,
+altogether irrespective of those great secular changes by which
+hot or cold epochs are produced, and which can hardly be called
+"catastrophistic," as they are produced gradually, and are
+liable to recur at definite intervals.
+</p>
+
+<p class="indent">
+Admitting, then, that there <i>is</i> a truth at the bottom of
+the once current doctrines of catastrophism, still it remains
+certain that the history of the earth has been one of <i>law</i>
+in all past time, as it is now. Nor need we shrink back affrighted
+at the vastness of the conception&mdash;the vaster for its very
+vagueness&mdash;that we are thus compelled to form as to the
+duration of <i>geological time</i>. As we grope our way backward
+through the dark labyrinth of the ages, epoch succeeds to epoch,
+and period to period, each looming more gigantic in its outlines
+and more shadowy in its features, as it rises, dimly revealed, from
+the mist and vapour of an older and ever-older past. It is useless
+to add century to century or millennium to millennium. When we
+pass a certain boundary-line, which, after all, is reached very
+soon, figures cease to convey to our finite faculties any real
+notion of the periods with which we have to deal. The astronomer
+can employ material illustrations to give form and substance
+to our conceptions of celestial space; but such a resource is
+unavailable to the geologist. The few thousand years of which
+we have historical evidence sink into absolute insignificance
+beside the unnumbered æons which unroll themselves one by
+one as we penetrate the dim recesses of the past, and decipher
+with feeble vision the ponderous volumes in which the record of
+the earth is written. Vainly does the strained intellect seek to
+overtake an ever-receding commencement, and toil to gain some
+adequate grasp of an apparently endless succession. A beginning
+there must have been, though we can never hope to fix its point.
+Even speculation droops her wings in the attenuated atmosphere
+of a past so remote, and the light of imagination is quenched
+in the darkness of a history so ancient. In <i>time</i>, as in
+<i>space</i>, the confines of the universe must ever remain
+concealed from us, and of the end we know no more than of the
+beginning. Inconceivable as is to us the lapse of "geological
+time," it is no more than "a mere moment of the past, a mere
+infinitesimal portion of eternity." Well may "the human heart,
+that weeps and trembles," say, with Richter's pilgrim through
+celestial space, "I will go no farther; for the spirit of man
+acheth with
+<a name="page_10"><span class="page">Page 10</span></a>
+this infinity. Insufferable is the glory of God. Let me lie
+down in the grave, and hide me from the persecution of the
+Infinite, for end, I see, there is none."
+</p>
+
+<h3>CHAPTER I.</h3>
+
+<p class="subtitle">
+THE SCOPE AND MATERIALS OF PALÆONTOLOGY.
+</p>
+
+<p class="indent">
+The study of the rock-masses which constitute the crust of the
+earth, if carried out in the methodical and scientific manner of
+the geologist, at once brings us, as has been before remarked, in
+contact with the remains or traces of living beings which formerly
+dwelt upon the globe. Such remains are found, in greater or less
+abundance, in the great majority of rocks; and they are not only of
+great interest in themselves, but they have proved of the greatest
+importance as throwing light upon various difficult problems in
+geology, in natural history, in botany, and in philosophy. Their
+study constitutes the science of palæontology; and though it
+is possible to proceed to a certain length in geology and zoology
+without much palæontological knowledge, it is hardly possible
+to attain to a satisfactory general acquaintance with either of
+these subjects without having mastered the leading facts of the
+first. Similarly, it is not possible to study palæontology
+without some acquaintance with both geology and natural history.
+</p>
+
+<p class="indent">
+Palæontology, then, is the science which treats of the living
+beings, whether animal or vegetable, which have inhabited the earth
+during past periods of its history. Its object is to elucidate,
+as far as may be, the structure, mode of existence, and habits
+of all such ancient forms of life; to determine their position
+in the scale of organised beings; to lay down the geographical
+limits within which they flourished; and to fix the period of
+their advent and disappearance. It is the ancient life-history
+of the earth; and were its record complete, it would furnish
+us with a detailed knowledge of the form and relations of all
+the animals and plants which have at any period flourished upon
+the land-surfaces of the globe or inhabited its waters; it would
+enable us to determine precisely their succession in time; and
+it would place in our hands an unfailing key to the problems of
+evolution. Unfortunately, from causes which will be subsequently
+discussed, the palæontological record is extremely imperfect,
+and our knowledge is interrupted
+<a name="page_11"><span class="page">Page 11</span></a>
+by gaps, which not only bear a large proportion to our solid
+information, but which in many cases are of such a nature that
+we can never hope to fill them up.
+</p>
+
+<p class="indent">
+FOSSILS.&mdash;The remains of animals or vegetables which we now
+find entombed in the solid rock, and which constitute the working
+material of the palæontologist, are termed "fossils,"[3] or
+"petrifactions." In most cases, as can be readily understood,
+fossils are the actual hard parts of animals and plants which
+were in existence when the rock in which they are now found was
+being deposited. Most fossils, therefore, are of the nature of
+the shells of shell-fish, the skeletons of coral-zoophytes, the
+bones of vertebrate animals, or the wood, bark, or leaves of
+plants. All such bodies are more or less of a hard consistence
+to begin with, and are capable of resisting decay for a longer
+or shorter time&mdash;hence the frequency with which they occur
+in the fossil condition. Strictly speaking, however, by the term
+"fossil" must be understood "any body, <i>or the traces of the
+existence of any body</i>, whether animal or vegetable, which
+has been buried in the earth by natural causes" (Lyell). We shall
+find, in fact, that many of the objects which we have to study
+as "fossils" have never themselves actually formed parts of any
+animal or vegetable, though they are due to the former existence
+of such organisms, and indicate what was the nature of these.
+Thus the footprints left by birds, or reptiles, or quadrupeds
+upon sand or mud, are just as much proofs of the former existence
+of these animals as would be bones, feathers, or scales, though
+in themselves they are inorganic. Under the head of fossils,
+therefore, come the footprints of air-breathing vertebrate animals;
+the tracks, trails, and burrows of sea-worms, crustaceans, or
+molluscs; the impressions left on the sand by stranded jelly-fishes;
+the burrows in stone or wood of certain shell-fish; the "moulds"
+or "casts" of shells, corals, and other organic remains; and
+various other bodies of a more or less similar nature.
+</p>
+
+<p class="footnote">
+[Footnote 3: Lat. <i>fossus</i>, dug up.]
+</p>
+
+<p class="indent">
+FOSSILISATION.&mdash;The term "fossilisation" is applied to all those
+processes through which the remains of organised beings may pass
+in being converted into fossils. These processes are numerous
+and varied; but there are three principal modes of fossilisation
+which alone need be considered here. In the first instance, the
+fossil is to all intents and purposes an actual portion of the
+original organised being&mdash;such as a bone, a shell, or a piece
+of wood. In some rare instances, as in the case of the body of
+the Mammoth discovered embedded in ice at the mouth of the Lena
+in Siberia, the fossil may be preserved
+<a name="page_12"><span class="page">Page 12</span></a>
+almost precisely in its original condition, and even with its soft
+parts uninjured. More commonly, certain changes have taken place
+in the fossil, the principal being the more or less total removal
+of the organic matter originally present. Thus bones become light
+and porous by the removal of their gelatine, so as to cleave to
+the tongue on being applied to that organ; whilst shells become
+fragile, and lose their primitive colours. In other cases, though
+practically the real body it represents, all the cavities of the
+fossil, down to its minutest recesses, may have become infiltrated
+with mineral matter. It need hardly be added, that it is in the
+more modern rocks that we find the fossils, as a rule, least
+changed from their former condition; but the original structure
+is often more or less completely retained in some of the fossils
+from even the most ancient formations.
+</p>
+
+<p class="indent">
+In the second place, we very frequently meet with fossils in
+the state of "casts" or moulds of the original organic body.
+What occurs in this case will be readily understood if we imagine
+any common bivalve shell, as an Oyster, or Mussel, or Cockle,
+embedded in clay or mud. If the clay were sufficiently soft and
+fluid, the first thing would be that it would gain access to the
+interior of the shell, and would completely fill up the space
+between the valves. The pressure, also, of the surrounding matter
+would insure that the clay would everywhere adhere closely to
+the exterior of the shell. If now we suppose the clay to be in
+any way hardened so as to be converted into stone, and if we were
+to break up the stone, we should obviously have the following
+state of parts. The clay which filled the shell would form an
+accurate cast of the <i>interior</i> of the shell, and the clay
+outside would give us an exact impression or cast of
+the <i>exterior</i> of the shell (fig. 1). We should have, then,
+
+<span style="float: left; margin: 4px; width: 260px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig001.jpg" width="252" height="179" alt="Fig. 1" />
+<br />
+Fig. 1.&mdash;<i>Trigonia longa</i>, showing casts of the exterior
+and interior of the shell.&mdash;Cretaceous (Neocomian).
+</span>
+
+two casts, an interior and an exterior, and the two would be
+very different to one another, since the inside of a shell is
+very unlike the outside. In the case, in fact, of many univalve
+shells, the interior cast or "mould" is so unlike the exterior
+cast, or unlike the shell itself, that it may be difficult to
+determine the true origin of the former.
+</p>
+
+<p class="indent">
+It only remains to add that there is sometimes a further
+complication. If the rock be very porous and permeable by
+<a name="page_13"><span class="page">Page 13</span></a>
+water, it may happen that the original shell is
+entirely dissolved away, leaving the interior cast loose,
+like the kernel of a nut, within the case formed by the exterior
+cast. Or it may happen that subsequent to the attainment of this
+state of things, the space thus left vacant between the interior
+and exterior cast&mdash;the space, that is, formerly occupied by
+the shell itself&mdash;may be filled up by some foreign mineral
+deposited there by the infiltration of water. In this last case
+the splitting open of the rock would reveal an interior cast,
+an exterior cast, and finally a body which would have the exact
+form of the original shell, but which would be really a much
+later formation, and which would not exhibit under the microscope
+the minute structure of shell.
+</p>
+
+<p class="indent">
+In the third class of cases we have fossils which present with
+the greatest accuracy the external form, and even sometimes the
+internal minute structure, of the original organic body, but
+which, nevertheless, are not themselves truly organic, but have
+been formed by a "replacement" of the particles of the primitive
+organism by some mineral substance. The most elegant example of
+this is afforded by fossil wood which has been "silicified" or
+converted into flint (<i>silex</i>). In such cases we have fossil
+wood which presents the rings of growth and fibrous structure of
+recent wood, and which under the microscope exhibits the minutest
+vessels which characterise ligneous tissue, together with the even
+more minute markings of the vessels (fig. 2). The whole, however,
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 268px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig002.jpg" width="260" height="260" alt="Fig. 2" />
+<br />
+Fig. 2.&mdash;Microscopic section of the silicified
+wood of a Conifer (<i>Sequoia</i>) cut in the long direction
+of the fibres. Post-tertiary? Colorado. (Original.)
+</span>
+
+<span style="width: 271px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig003.jpg" width="263" height="260" alt="Fig. 3" />
+<br />
+Fig. 3.&mdash;Microscopic section of the wood of the
+common Larch (<i>Abies larix</i>), cut in the long direction
+of the fibres. In both the fresh and the fossil wood (fig. 2)
+are seen the discs characteristic of coniferous wood. (Original.)
+</span>
+
+</span>
+
+instead of being composed of the original carbonaceous matter of
+the wood, is now converted into flint. The only explanation that
+can be given
+<a name="page_14"><span class="page">Page 14</span></a>
+of this by no means rare phenomenon, is that the wood must have
+undergone a slow process of decay in water charged with silica or
+flint in solution. As each successive particle of wood was removed
+by decay, its place was taken by a particle of flint deposited
+from the surrounding water, till ultimately the entire wood was
+silicified. The process, therefore, resembles what would take
+place if we were to pull down a house built of brick by successive
+bricks, replacing each brick as removed by a piece of stone of
+precisely the same size and form. The result of this would be that
+the house would retain its primitive size, shape, and outline, but
+it would finally have been converted from a house of brick into a
+house of stone. Many other fossils besides wood&mdash;such as shells,
+corals, sponges, &amp;c.&mdash;are often found silicified; and this
+may be regarded as the commonest form of fossilisation by replacement.
+In other cases, however, though the principle of the process is the
+same, the replacing substance may be iron pyrites, oxide of iron,
+sulphur, malachite, magnesite, talc, &amp;c.; but it is rarely that
+the replacement with these minerals is so perfect as to preserve the
+more delicate details of internal structure.
+</p>
+
+<h3>CHAPTER II.</h3>
+
+<p class="subtitle">
+THE FOSSILIFEROUS ROCKS.
+</p>
+
+<p class="indent">
+Fossils are found in rocks, though not universally or promiscuously;
+and it is therefore necessary that the palæontologist should
+possess some acquaintance with, at any rate, those rocks which
+yield organic remains, and which are therefore said to be
+"<i>fossiliferous</i>." In geological language, all the materials
+which enter into the composition of the solid crust of the earth,
+be their texture what it may&mdash;from the most impalpable mud to
+the hardest granite&mdash;are termed "rocks;" and for our present
+purpose we may divide these into two great groups. In the first
+division are the <i>Igneous Rocks</i>&mdash;such as the lavas and
+ashes of volcanoes&mdash;which are formed within the body of the
+earth itself, and which owe their structure and origin to the
+action of heat. The Igneous Rocks are formed primarily below the
+surface of the earth, which they only reach as the result of
+volcanic action; they are generally destitute of distinct
+"stratification," or arrangement in successive layers; and they
+do not contain fossils, except in the comparatively
+<a name="page_15"><span class="page">Page 15</span></a>
+rare instances where volcanic ashes have enveloped
+animals or plants which were living in the sea or on the land in
+the immediate vicinity of the volcanic focus. The second great
+division of rocks is that of the <i>Fossiliferous, Aqueous</i>,
+or <i>Sedimentary</i> Rocks. These are formed at the surface of
+the earth, and, as implied by one of their names, are invariably
+deposited in water. They are produced by vital or chemical action,
+or are formed from the "sediment" produced by the disintegration
+and reconstruction of previously existing rocks, without previous
+solution; they mostly contain fossils; and they are arranged in
+distinct layers or "strata." The so-called "aerial" rocks which,
+like beds of blown sand, have been formed by the action of the
+atmosphere, may also contain fossils; but they are not of such
+importance as to require special notice here.
+</p>
+
+<p class="indent">
+For all practical purposes, we may consider that the Aqueous
+Rocks are the natural cemetery of the animals and plants of bygone
+ages; and it is therefore essential that the palæontological
+student should be acquainted with some of the principal facts as
+to their physical characters, their minute structure and mode of
+origin, their chief varieties, and their historical succession.
+</p>
+
+<p class="indent">
+The Sedimentary or Fossiliferous Rocks form the greater portion of
+that part of the earth's crust which is open to our examination, and
+are distinguished by the fact that they are regularly "stratified" or
+arranged in distinct and definite layers or "strata." These layers
+may consist of a single material, as in a block of sandstone, or
+they may consist of different materials. When examined on a large
+scale, they are always found to consist of alternations of layers
+of different mineral composition. We may examine any given area,
+and find in it nothing but one kind of rock&mdash;sandstone, perhaps,
+or limestone. In all cases, however, if we extend our examination
+sufficiently far, we shall ultimately come upon different rocks;
+and, as a general rule, the thickness of any particular set of
+beds is comparatively small, so that different kinds of rock
+alternate with one another in comparatively small spaces.
+</p>
+
+<p class="indent">
+As regards the origin of the Sedimentary Rocks, they are for
+the most part "derivative" rocks, being derived from the wear
+and tear of pre-existent rocks. Sometimes, however, they owe
+their origin to chemical or vital action, when they would more
+properly be spoken of simply as Aqueous Rocks. As to their mode
+of deposition, we are enabled to infer that the materials which
+compose them have formerly been spread out by the action of water,
+from what we see going on every day
+<a name="page_16"><span class="page">Page 16</span></a>
+at the mouths of our great
+rivers, and on a smaller scale wherever there is running water.
+Every stream, where it runs into a lake or into the sea, carries
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig004.jpg" width="571" height="429" alt="Fig. 4" />
+<br />
+Fig. 4.&mdash;Sketch of Carboniferous strata at Kinghorn, in Fife,
+showing stratified beds (limestone and shales) surmounted by an
+unstratified mass of trap. (Original.)
+</span>
+</span>
+
+with it a burden of mud, sand, and rounded pebbles, derived from
+the waste of the rocks which form its bed and banks. When these
+materials cease to be impelled by the force of the moving water,
+they sink to the bottom, the heaviest pebbles, of course, sinking
+first, the smaller pebbles and sand next, and the finest mud
+last. Ultimately, therefore, as might have been inferred upon
+theoretical grounds, and as is proved by practical experience,
+every lake becomes a receptacle for a series of stratified rocks
+produced by the streams flowing into it. These deposits may vary
+in different parts of the lake, according as one stream brought
+down one kind of material and another stream contributed another
+material; but in all cases the materials will bear ample evidence
+that they were produced, sorted, and deposited by running water.
+The finer beds of clay or sand will all be arranged in thicker or
+thinner layers or laminæ; and if there are any beds of pebbles
+these will all be rounded or smooth, just like the water-worn
+pebbles of any brook-course. In all probability, also, we should
+find in some of the beds the remains
+<a name="page_17"><span class="page">Page 17</span></a>
+of fresh-water shells or plants or other organisms which inhabited
+the lake at the time these beds were being deposited.
+</p>
+
+<p class="indent">
+In the same way large rivers&mdash;such as the Ganges or
+Mississippi&mdash;deposit all the materials which they bring down
+at their mouths, forming in this way their "deltas." Whenever
+such a delta is cut through, either by man or by some channel of
+the river altering its course, we find that it is composed of a
+succession of horizontal layers or strata of sand or mud, varying
+in mineral composition, in structure, or in grain, according to
+the nature of the materials brought down by the river at different
+periods. Such deltas, also, will contain the remains of animals
+which inhabit the river, with fragments of the plants which grew
+on its banks, or bones of the animals which lived in its basin.
+</p>
+
+<p class="indent">
+Nor is this action confined, of course, to large rivers only,
+though naturally most conspicuous in the greatest bodies of water.
+On the contrary, all streams, of whatever size, are engaged in
+the work of wearing down the dry land, and of transporting the
+materials thus derived from higher to lower levels, never resting
+in this work till they reach the sea.
+</p>
+
+<p class="indent">
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig005.jpg" width="571" height="385" alt="Fig. 5" />
+Fig. 5.&mdash;Diagram to illustrate the formation of sedimentary
+deposits at the point where a river debouches into the sea.
+</span>
+</span>
+Lastly, the sea itself&mdash;irrespective of the materials
+delivered into it by rivers&mdash;is constantly preparing fresh
+<a name="page_18"><span class="page">Page 18</span></a>
+by its own action.
+Upon every coast-line the sea is constantly eating back into
+the land and reducing its component rocks to form the shingle
+and sand which we see upon every shore. The materials thus
+produced are not, however, lost, but are ultimately deposited
+elsewhere in the form of new stratified accumulations, in which
+are buried the remains of animals inhabiting the sea at the time.
+</p>
+
+<p class="indent">
+Whenever, then, we find anywhere in the interior of the land
+any series of beds having these characters&mdash;composed, that is,
+of distinct layers, the particles of which, both large and small,
+show distinct traces of the wearing action of water&mdash;whenever
+and wherever we find such rocks, we are justified in assuming that
+they have been deposited by water in the manner above mentioned.
+Either they were laid down in some former lake by the combined
+action of the streams which flowed into it; or they were deposited
+at the mouth of some ancient river, forming its delta; or they
+were laid down at the bottom of the ocean. In the first two cases,
+any fossils which the beds might contain would be the remains
+of fresh-water or terrestrial organisms. In the last case, the
+majority, at any rate, of the fossils would be the remains of
+marine animals.
+</p>
+
+<p class="indent">
+The term "formation" is employed by geologists to express "any
+group of rocks which have some character in common, whether of
+origin, age, or composition" (Lyell); so that we may speak of
+stratified and unstratified formations, aqueous or igneous
+formations, fresh-water or marine formations, and so on.
+</p>
+
+<h4>CHIEF DIVISIONS OF THE AQUEOUS ROCKS.</h4>
+
+<p class="indent">
+The Aqueous Rocks may be divided into two great sections, the
+Mechanically-formed and the Chemically-formed, including under
+the last head all rocks which owe their origin to vital action,
+as well as those produced by ordinary chemical agencies.
+</p>
+
+<p class="indent">
+A. MECHANICALLY-FORMED ROCKS.&mdash;These are all those Aqueous
+Rocks of which we can obtain proofs that their particles have
+been mechanically transported to their present situation. Thus,
+if we examine a piece of <i>conglomerate</i> or puddingstone, we
+find it to be composed of a number of rounded pebbles embedded
+in an enveloping matrix or paste, which is usually of a sandy
+nature, but may be composed of carbonate of lime (when the rock
+is said to be a "calcareous conglomerate"). The pebbles in all
+conglomerates are worn and rounded by the action of water in motion,
+and thus show
+<a name="page_19"><span class="page">Page 19</span></a>
+that they have been subjected
+to much mechanical attrition, whilst they have been mechanically
+transported for a greater or less distance from the rock of which
+they originally formed part. The analogue of the old conglomerates
+at the present day is to be found in the great beds of shingle
+and gravel which are formed by the action of the sea on every
+coast-line, and which are composed of water-worn and well-rounded
+pebbles of different sizes. A <i>breccia</i> is a mechanically-formed
+rock, very similar to a conglomerate, and consisting of larger or
+smaller fragments of rock embedded in a common matrix. The fragments,
+however, are in this case all more or less angular, and are not
+worn or rounded. The fragments in breccias may be of large size,
+or they may be comparatively small (fig. 6); and the matrix may
+
+<span style="float: right; margin: 4px; width: 268px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig006.jpg" width="260" height="258" alt="Fig. 6" />
+<br />
+Fig. 6.&mdash;Microscopic section of a calcareous breccia in the
+Lower Silurian (Coniston Limestone) of Shap Wells, Westmoreland.
+The fragments are all of small size, and consist of angular
+pieces of transparent quartz, volcanic ashes, and limestone
+embedded in a matrix of crystalline limestone. (Original.)
+</span>
+
+be composed of sand (arenaceous) or of carbonate of lime
+(calcareous). In the case of an ordinary sandstone, again, we
+have a rock which may be regarded as simply a very fine-grained
+conglomerate or breccia, being composed of small grains of sand
+(silica), sometimes rounded, sometimes more or less angular,
+cemented together by some such substance as oxide of iron, silicate
+of iron, or carbonate of lime. A sandstone, therefore, like a
+conglomerate is a mechanically-formed rock, its component grams
+being equally the result of mechanical attrition and having equally
+been transported from a distance; and the same is true of the
+ordinary sand of the sea-shore, which is nothing more than an
+unconsolidated sandstone. Other so-called sands and sandstones,
+though equally mechanical in their origin, are truly calcareous in
+their nature, and are more or less entirely composed of carbonate
+of lime. Of this kind are the shell-sand so common on our coasts,
+and the coral-sand which is so largely formed in the neighbourhood
+of coral-reefs. In these cases the rock is composed of fragments
+of the skeletons of shellfish, and numerous other marine animals,
+together, in many instances, with the remains of certain sea-weeds
+(<i>Corallines</i>, <i>Nullipores</i>, &amp;c,) which are endowed
+with the power of secreting
+<a name="page_20"><span class="page">Page 20</span></a>
+carbonate of lime from the sea-water. Lastly, in certain rocks
+still finer in their texture than sandstones, such as the various
+mud-rocks and shales, we can still recognise a mechanical source
+and origin. If slices of any of these rocks sufficiently thin to
+be transparent are examined under the microscope, it will be found
+that they are composed of minute grains of different sizes, which
+are all more or less worn and rounded, and which clearly show,
+therefore, that they have been subjected to mechanical attrition.
+</p>
+
+<p class="indent">
+All the above-mentioned rocks, then, are <i>mechanically-formed</i>
+rocks; and they are often spoken of as "Derivative Rocks," in
+consequence of the fact that their particles can be shown to have
+been mechanically <i>derived</i> from other pre-existent rocks.
+It follows from this that every bed of any mechanically-formed
+rock is the measure and equivalent of a corresponding amount of
+destruction of some older rock. It is not necessary to enter
+here into a minute account of the subdivisions of these rocks, but
+it may be mentioned that they may be divided into two principal
+groups, according to their chemical composition. In the one group
+we have the so-called <i>Arenaceous</i> (Lat. <i>arena</i>, sand)
+or <i>Siliceous</i> Rocks, which are essentially composed of
+larger or smaller grains of flint or silica. In this group are
+comprised ordinary sand, the varieties of sandstone and grit, and
+most conglomerates and breccias. We shall, however, afterwards
+see that some siliceous rocks are of organic origin. In the second
+group are the so-called <i>Argillaceous</i> (Lat. <i>argilla</i>,
+clay) Rocks, which contain a larger or smaller amount of clay or
+hydrated silicate of alumina in their composition. Under this
+head come clays, shales, marls, marl-slate, clay-slates, and
+most flags and flagstones.
+</p>
+
+<p class="indent">
+B. CHEMICALLY-FORMED ROCKS.&mdash;In this section are comprised all
+those Aqueous or Sedimentary Rocks which have been formed by
+chemical agencies. As many of these chemical agencies, however,
+are exerted through the medium of living beings, whether animals
+or plants, we get into this section a number of what may be called
+"<i>organically-formed rocks</i>." These are of the greatest
+possible importance to the palæontologist, as being to a
+greater or less extent composed of the actual remains of animals or
+vegetables, and it will therefore be necessary to consider their
+character and structure in some detail.
+</p>
+
+<p class="indent">
+By far the most important of the chemically-formed rocks are
+the so-called <i>Calcareous Rocks</i> (Lat. <i>calx</i>, lime),
+comprising all those which contain a large proportion of carbonate
+<a name="page_21"><span class="page">Page 21</span></a>
+of lime, or are wholly composed of this substance.
+Carbonate of lime is soluble in water holding a certain amount
+of carbonic acid gas in solution; and it is, therefore, found in
+larger or smaller quantity dissolved in all natural waters, both
+fresh and salt, since these waters are always to some extent
+charged with the above-mentioned solvent gas. A great number of
+aquatic animals, however, together with some aquatic plants, are
+endowed with the power of separating the lime thus held in
+solution in the water, and of reducing it again to its solid
+condition. In this way shell-fish, crustaceans, sea-urchins,
+corals, and an immense number of other animals, are enabled to
+construct their skeletons; whilst some plants form hard structures
+within their tissues in a precisely similar manner. We do meet
+with some calcareous deposits, such as the "stalactites" and
+"stalagmites" of caves, the "calcareous tufa" and "travertine"
+of some hot springs, and the spongy calcareous deposits of
+so-called "petrifying springs," which are purely chemical in
+their origin, and owe nothing to the operation of living beings.
+Such deposits are formed simply by the precipitation of carbonate
+of lime from water, in consequence of the evaporation from the
+water of the carbonic acid gas which formerly held the lime in
+solution; but, though sometimes forming masses of considerable
+thickness and of geological importance, they do not concern us
+here. Almost all the limestones which occur in the series of the
+stratified rocks are, primarily at any rate, of <i>organic</i>
+origin, and have been, directly or indirectly, produced by the
+action of certain lime-making animals or plants, or both combined.
+The presumption as to all the calcareous rocks, which cannot be
+clearly shown to have been otherwise produced, is that they are
+thus organically formed; and in many cases this presumption can
+be readily reduced to a certainty. There are many varieties of
+the calcareous rocks, but the following are those which are of
+the greatest importance:&mdash;
+</p>
+
+<p class="indent">
+<i>Chalk</i> is a calcareous rock of a generally soft and
+pulverulent texture, and with an earthy fracture. It varies in
+its purity, being sometimes almost wholly composed of carbonate
+of lime, and at other times more or less intermixed with foreign
+matter. Though usually soft and readily reducible to powder,
+chalk is occasionally, as in the north of Ireland, tolerably
+hard and compact; but it never assumes the crystalline aspect
+and stony density of limestone, except it be in immediate contact
+with some mass of igneous rock. By means of the microscope, the
+true nature and mode of formation of chalk can be determined
+with the greatest ease. In the case of the harder varieties, the
+examination can be conducted by means of
+<a name="page_22"><span class="page">Page 22</span></a>
+slices ground down to a thinness sufficient to render them
+transparent; but in the softer kinds the rock must be disintegrated
+under water, and the <i>débris</i> examined microscopically.
+When investigated by either of these methods, chalk is found to be
+a genuine organic rock, being composed of the shells or hard parts
+of innumerable marine animals of different kinds, some entire,
+some fragmentary, cemented together by a matrix of very finely
+granular carbonate of lime. Foremost amongst the animal remains
+which so largely compose chalk are the shells of the minute
+creatures which will be subsequently spoken of under the name of
+<i>Foraminifera</i> (fig. 7), and which, in spite of their
+
+<span style="float: left; margin: 4px; width: 271px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig007.jpg" width="263" height="261" alt="Fig. 7" />
+<br />
+Fig. 7.&mdash;Section of Gravesend Chalk, examined by transmitted
+light and highly magnified. Besides the entire shells of
+<i>Globigerina</i>, <i>Rotalia</i>, and <i>Textularia</i>,
+numerous detached chambers of <i>Globigerina</i> are seen.
+(Original.)
+</span>
+
+microscopic dimensions, play a more important part in the process
+of lime-making than perhaps any other of the larger inhabitants of
+the ocean.
+</p>
+
+<p class="indent">
+As chalk is found in beds of hundreds of feet in thickness,
+and of great purity, there was long felt much difficulty in
+satisfactorily accounting for its mode of formation and origin.
+By the researches of Carpenter, Wyville Thomson, Huxley, Wallich,
+and others, it has, however, been shown that there is now forming,
+in the profound depths of our great oceans, a deposit which is
+in all essential respects identical with chalk, and which is
+generally known as the "Atlantic ooze," from its having been first
+discovered in that sea. This ooze is found at great depths (5000
+to over 15,000 feet) in both the Atlantic and Pacific, covering
+enormously large areas of the sea-bottom, and it presents itself
+as a whitish-brown, sticky, impalpable mud, very like greyish
+chalk when dried. Chemical examination shows that the ooze is
+composed almost wholly of carbonate of lime, and microscopical
+examination proves it to be of organic origin, and to be made up
+of the remains of living beings. The principal forms of these
+belong to the <i>Foraminifera</i>, and the commonest of these
+are the irregularly-chambered shells of <i>Globigerina</i>,
+absolutely indistinguishable from the <i>Globigerinœ</i>
+which are so largely present in the chalk (fig. 8). Along with
+these occur fragments of the skeletons of other larger creatures,
+<a name="page_23"><span class="page">Page 23</span></a>
+and a certain proportion of the flinty cases of minute animal
+and vegetable organisms (<i>Polycystina</i> and <i>Diatoms</i>).
+
+<span style="float: right; margin: 4px; width: 275px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig008.jpg" width="263" height="258" alt="Fig. 8" />
+<br />
+Fig. 8.&mdash;Organisms in the Atlantic Ooze, chiefly
+<i>Foraminifera</i> (<i>Globigerina</i> and <i>Textularia</i>),
+with <i>Polycystina</i> and sponge-spicules; highly magnified.
+(Original.)
+</span>
+
+Though many of the minute animals, the hard parts of which form
+the ooze, undoubtedly live at or near the surface of the sea,
+others, probably, really live near the bottom; and the ooze itself
+forms a congenial home for numerous sponges, sea-lilies, and
+other marine animals which flourish at great depths in the sea.
+There is thus established an intimate and most interesting
+parallelism between the chalk and the ooze of modern oceans.
+Both are formed essentially in the same way, and the latter only
+requires consolidation to become actually converted into chalk. Both
+are fundamentally organic deposits, apparently requiring a great
+depth of water for their accumulation, and mainly composed of the
+remains of <i>Foraminifera</i>, together with the entire or broken
+skeletons of other marine animals of greater dimensions. It is to be
+remembered, however, that the ooze, though strictly representative
+of the chalk, cannot be said in any proper sense to be actually
+<i>identical</i> with the formation so called by geologists. A
+great lapse of time separates the two, and though composed of
+the remains of representative classes or groups of animals, it
+is only in the case of the lowly-organised <i>Globigerinœ</i>,
+and of some other organisms of little higher grade, that we find
+absolutely the same kinds or species of animals in both.
+</p>
+
+<p class="indent">
+<i>Limestone</i>, like chalk, is composed of carbonate of lime,
+sometimes almost pure, but more commonly with a greater or less
+intermixture of some foreign material, such as alumina or silica.
+The varieties of limestone are almost innumerable, but the great
+majority can be clearly proved to agree with chalk in being
+essentially of organic origin, and in being more or less largely
+composed of the remains of living beings. In many instances the
+organic remains which compose limestone are so large as to be
+readily visible to the naked eye, and the rock is at once seen to
+be nothing more than an agglomeration of the skeletons, generally
+fragmentary, of certain marine animals, cemented together by a
+matrix of carbonate of lime.
+<a name="page_24"><span class="page">Page 24</span></a>
+This is the
+case, for example, with the so-called "Crinoidal Limestones" and
+"Encrinital Marbles" with which the geologist is so familiar,
+especially as occurring in great beds amongst the older formations
+of the earth's crust. These are seen, on weathered or broken
+surfaces, or still better in polished slabs (fig. 9), to be
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 493px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig009.jpg" width="485" height="360" alt="Fig. 9" />
+<br />
+Fig. 9.&mdash;Slab of Crinoidal marble, from the Carboniferous
+limestone of Dent, in Yorkshire, of the natural size. The polished
+surface intersects the columns of the Crinoids at different angles,
+and thus gives rise to varying appearances. (Original.)
+</span>
+</span>
+
+composed more or less exclusively of the
+broken stems and detached plates of sea-lilies (<i>Crinoids</i>).
+Similarly, other limestones are composed almost entirely of the
+skeletons of corals; and such old coralline limestones can readily
+be paralleled by formations which we can find in actual course of
+production at the present day. We only need to transport ourselves
+to the islands of the Pacific, to the West Indies, or to the Indian
+Ocean, to find great masses of lime formed similarly by living
+corals, and well known to everyone under the name of "coral-reefs."
+Such reefs are often of vast extent, both superficially and in
+vertical thickness, and they fully equal in this respect any of
+the coralline limestones of bygone ages. Again, we find other
+limestones&mdash;such as the celebrated "Nummulitic Limestone"
+(fig. 10), which sometimes attains a thickness of some thousands
+of feet&mdash;which are almost entirely made up of the shells of
+<i>Foraminifera</i>. In the case of the "Nummulitic Limestone,"
+just mentioned, these shells are of large size, varying from the
+up to that of a
+<a name="page_25"><span class="page">Page 25</span></a>
+florin. There are, however, as we shall see, many other limestones,
+which are likewise largely made up of <i>Foraminifera</i>, but in
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 414px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig010.jpg" width="406" height="319" alt="Fig. 10" />
+<br/>
+Fig. 10.&mdash;Piece of Nummulitic Limestone from the Great Pyramid.
+Of the natural size. (Original.)
+</span>
+</span>
+
+which the shells are very much more minute, and would hardly be
+seen at all without the microscope.
+</p>
+
+<p class="indent">
+We may, in fact, consider that the great agents in the production
+of limestones in past ages have been animals belonging to the
+<i>Crinoids</i>, the <i>Corals</i>, and the <i>Foraminifera</i>.
+At the present day, the Crinoids have been nearly extinguished,
+and the few known survivors seem to have retired to great depths
+in the ocean; but the two latter still actively carry on the
+work of lime-making, the former being very largely helped in
+their operations by certain lime-producing marine plants
+(<i>Nullipores</i> and <i>Corallines</i>). We have to remember,
+however, that though the limestones, both ancient and modern,
+that we have just spoken of, are truly organic, they are not
+necessarily formed out of the remains of animals which actually
+lived on the precise spot where we now find the limestone itself.
+We may find a crinoidal limestone, which we can show to have
+been actually formed by the successive growth of generations
+of sea-lilies <i>in place</i>; but we shall find many others in
+which the rock is made up of innumerable fragments of the skeletons
+of these creatures, which have been clearly worn and rubbed by
+the sea-waves, and which have been mechanically transported to
+their present site. In the same way, a limestone may be shown
+to have been an actual coral-reef, by the fact that we find in
+it great masses of coral, growing in their natural position, and
+<a name="page_26"><span class="page">Page 26</span></a>
+exhibiting plain proofs that they were
+simply quietly buried by the calcareous sediment as they grew; but
+other limestones may contain only numerous rolled and water-worn
+fragments of corals. This is precisely paralleled by what we can
+observe in our existing coral-reefs. Parts of the modern
+coral-islands and coral-reefs are really made up of corals, dead
+or alive, which actually grew on the spot where we now find them;
+but other parts are composed of a limestone-rock ("coral-rock"),
+or of a loose sand ("coral-sand"), which is organic in the sense
+that it is composed of lime formed by living beings, but which,
+in truth, is composed of fragments of the skeletons of these living
+beings, mechanically transported and heaped together by the sea. To
+take another example nearer home, we may find great accumulations
+of calcareous matter formed <i>in place</i>, by the growth of
+shell-fish, such as oysters or mussels; but we can also find
+equally great accumulations on many of our shores in the form of
+"shell-sand," which is equally composed of the shells of molluscs,
+but which is formed by the trituration of these shells by the
+mechanical power of the sea-waves. We thus see that though all
+these limestones are primarily organic, they not uncommonly become
+"mechanically-formed" rocks in a secondary sense, the materials
+of which they are composed being formed by living beings, but
+having been mechanically transported to the place where we now
+find them.
+</p>
+
+<p class="indent">
+Many limestones, as we have seen, are composed of large and
+conspicuous organic remains, such as strike the eye at once.
+Many others, however, which at first sight appear compact, more
+or less crystalline, and nearly devoid of traces of life, are
+found, when properly examined, to be also composed of the remains
+of various organisms. All the commoner limestones, in fact, from
+the Lower Silurian period onwards, can be easily proved to be thus
+<i>organic</i> rocks, if we investigate weathered or polished
+surfaces with a lens, or, still better, if we cut thin slices of
+the rock and grind these down till they are transparent. When
+thus examined, the rock is usually found to be composed of
+innumerable entire or fragmentary fossils, cemented together
+by a granular or crystalline matrix of carbonate of lime (figs.
+11 and 12). When the matrix is granular, the rock is precisely
+similar to chalk, except that it is harder and less earthy in
+texture, whilst the fossils are only occasionally referable to
+the <i>Foraminifera</i>. In other cases, the matrix is more or
+less crystalline, and when this crystallisation has been carried
+to a great extent, the original organic nature of the rock may
+be greatly or completely obscured
+<a name="page_27"><span class="page">Page 27</span></a>
+thereby. Thus, in limestones
+which have been greatly altered or "metamorphosed" by the combined
+action of heat and pressure, all traces of organic remains become
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 268px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig011.jpg" width="260" height="258" alt="Fig. 11" />
+<br />
+Fig. 11.&mdash;Section of Carboniferous Limestone from Spergen Hill,
+Indiana, U.S., showing numerous large-sized <i>Foraminifera</i>
+(<i>Endothyra</i>) and a few oolitic grains; magnified.
+(Original.)
+</span>
+
+<span style="width: 268px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig012.jpg" width="263" height="258" alt="Fig. 12" />
+<br />
+Fig 12.&mdash;Section of Coniston Limestone (Lower Silurian) from
+Keisler, Westmoreland; magnified. The matrix is very coarsely
+crystalline, and the included organic remains are chiefly stems
+of Crinoids. (Original.)
+</span>
+
+</span>
+
+annihilated, and the rock becomes completely crystalline throughout.
+This, for example, is the case with the ordinary white "statuary
+marble," slices of which exhibit under the microscope nothing but
+an aggregate of beautifully transparent crystals of carbonate
+of lime, without the smallest traces of fossils. There are also
+other cases, where the limestone is not necessarily highly
+crystalline, and where no metamorphic action in the strict sense
+has taken place, in which, nevertheless, the microscope fails
+to reveal any evidence that the rock is organic. Such cases are
+somewhat obscure, and doubtless depend on different causes in
+different instances; but they do not affect the important
+generalisation that limestones are fundamentally the product
+of the operation of living beings. This fact remains certain;
+and when we consider the vast superficial extent occupied by
+calcareous deposits, and the enormous collective thickness of
+these, the mind cannot fail to be impressed with the immensity of
+the period demanded for the formation of these by the agency of
+such humble and often microscopic creatures as Corals, Sea-lilies,
+Foraminifers, and Shell-fish.
+</p>
+
+<p class="indent">
+Amongst the numerous varieties of limestone, a few are of such
+interest as to deserve a brief notice. <i>Magnesian limestone</i>
+or <i>dolomite</i>, differs from ordinary limestone in containing
+a certain proportion of carbonate of magnesia along with the
+carbonate of lime. The typical dolomites contain a large proportion
+<a name="page_28"><span class="page">Page 28</span></a>
+of carbonate of magnesia, and are highly
+crystalline. The ordinary magnesian limestones (such as those of
+Durham in the Permian series, and the Guelph Limestones of North
+America in the Silurian series) are generally of a yellowish,
+buff, or brown colour, with a crystalline or pearly aspect,
+effervescing with acid much less freely than ordinary limestone,
+exhibiting numerous cavities from which fossils have been dissolved
+out, and often assuming the most varied and singular forms in
+consequence of what is called "concretionary action." Examination
+with the microscope shows that these limestones are composed of an
+aggregate of minute but perfectly distinct crystals, but that minute
+organisms of different kinds, or fragments of larger fossils, are
+often present as well. Other magnesian limestones, again, exhibit
+no striking external peculiarities by which the presence of magnesia
+would be readily recognised, and though the base of the rock is
+crystalline, they are replete with the remains of organised beings.
+Thus many of the magnesian limestones of the Carboniferous series
+of the North of England are very like ordinary limestone to look
+at, though effervescing less freely with acids, and the microscope
+proves them to be charged with the remains of <i>Foraminifera</i>
+and other minute organisms.
+</p>
+
+<p class="indent">
+<i>Marbles</i> are of various kinds, all limestones which are
+sufficiently hard and compact to take a high polish going by
+this name. Statuary marble, and most of the celebrated foreign
+marbles, are "metamorphic" rocks, of a highly crystalline nature,
+and having all traces of their primitive organic structure
+obliterated. Many other marbles, however, differ from ordinary
+limestone simply in the matter of density. Thus, many marbles
+(such as Derbyshire marble) are simply "crinoidal limestones"
+(fig. 9); whilst various other British marbles exhibit innumerable
+organic remains under the microscope. Black marbles owe their
+colour to the presence of very minute particles of carbonaceous
+matter, in some cases at any rate; and they may either be
+metamorphic, or they may be charged with minute fossils such as
+<i>Foraminifera</i> (<i>e.g.</i>, the black limestones of Ireland,
+and the black marble of Dent, in Yorkshire).
+</p>
+
+<p class="indent">
+"<i>Oolitic</i>" <i>limestones</i>, or "<i>oolites</i>," as they
+are often called, are of interest both to the palæontologist
+and geologist. The peculiar structure to which they owe their name
+is that the rock is more or less entirely composed of spheroidal
+or oval grains, which vary in size from the head of a small pin or
+less up to the size of a pea, and which may be in almost immediate
+contact with one another, or may be cemented together by a
+<a name="page_29"><span class="page">Page 29</span></a>
+more or less abundant calcareous matrix. When the
+grains are pretty nearly spherical and are in tolerably close
+contact, the rock looks very like the roe of a fish, and the name
+of "oolite" or "egg-stone" is in allusion to this. When the grains
+are of the size of peas or upwards, the rock is often called a
+"pisolite" (Lat. <i>pisum</i>, a pea). Limestones having this
+peculiar structure are especially abundant in the Jurassic formation,
+which is often called the "Oolitic series" for this reason; but
+essentially similar limestones occur not uncommonly in the Silurian,
+Devonian, and Carboniferous formations, and, indeed, in almost all
+rock-groups in which limestones are largely developed. Whatever may
+be the age of the formation in which they occur, and whatever may
+be the size of their component "eggs," the structure of oolitic
+limestones is fundamentally the same. All the ordinary oolitic
+limestones, namely, consist of little spherical or ovoid
+"concretions," as they are termed, cemented together by a larger
+or smaller amount of crystalline carbonate of lime, together, in
+many instances, with numerous organic remains of different kinds
+
+<span style="float: right; margin: 4px; width: 263px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig013.jpg" width="255" height="253" alt="Fig. 13" />
+<br />
+Fig. 13.&mdash;Slice of oolitic limestone from the Jurassic series
+(Coral Rag) of Weymouth; magnified. (Original.)
+</span>
+
+(fig. 13). When examined in polished slabs, or in thin sections
+prepared for the microscope, each of these little concretions is seen
+to consist of numerous concentric coats of carbonate of lime, which
+sometimes simply surround an imaginary centre, but which, more
+commonly, have been successively deposited round some foreign body,
+such as a little crystal of quartz, a cluster of sand-grains, or a
+minute shell. In other cases, as in some of the beds of the Carboniferous
+limestone in the North of England, where the limestone is highly
+"arenaceous," there is a modification of the oolitic structure.
+Microscopic sections of these sandy limestones (fig. 14) show
+numerous generally angular or oval grains of silica or flint, each
+of which is commonly surrounded by a thin coating of carbonate of
+lime, or sometimes by several such coats, the whole being cemented
+together along with the shells of <i>Foraminifera</i> and other
+minute fossils by a matrix of crystalline calcite. As compared
+with typical oolites, the concretions in these limestones are
+usually much more irregular in shape,
+<a name="page_30"><span class="page">Page 30</span></a>
+often lengthened out and
+almost cylindrical, at other times angular, the central nucleus
+
+<span style="float: left; margin: 4px; width: 254px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig014.jpg" width="252" height="248" alt="Fig. 14" />
+<br />
+Fig. 14.&mdash;Slice of arenaceous and oolitic limestone
+from the Carboniferous series of Shap, Westmoreland; magnified.
+The section also exhibit <i>Foraminifera</i> and other minute
+fossils. (Original.)
+</span>
+
+being of large size, and the surrounding envelope of lime being
+very thin, and often exhibiting no concentric structure. In both
+these and the ordinary oolites, the structure is fundamentally
+the same. Both have been formed in a sea, probably of no great
+depth, the waters of which were charged with carbonate of lime
+in solution, whilst the bottom was formed of sand intermixed with
+minute shells and fragments of the skeletons of larger marine
+animals. The excess of lime in the sea-water was precipitated
+round the sand-grams, or round the smaller shells, as so many
+nuclei, and this precipitation must often have taken place time
+after time, so as to give rise to the concentric structure so
+characteristic of oolitic concretions. Finally, the oolitic grains
+thus produced were cemented together by a further precipitation
+of crystalline carbonate of lime from the waters of the ocean.
+</p>
+
+<p class="indent">
+<i>Phosphate of Lime</i> is another lime-salt, which is of interest
+to the palæontologist. It does not occur largely in the
+stratified series, but it is found in considerable beds [4] in
+the Laurentian formation, and less abundantly in some later
+rock-groups, whilst it occurs abundantly in the form of nodules
+in parts of the Cretaceous (Upper Greensand) and Tertiary deposits.
+Phosphate of lime forms the larger proportion of the earthy matters
+of the bones of Vertebrate animals, and also occurs in less amount
+in the skeletons of certain of the Invertebrates (<i>e.g.</i>,
+<i>Crustacea</i>). It is, indeed, perhaps more distinctively than
+carbonate of lime, an organic compound; and though the formation
+of many known deposits of phosphate of
+<a name="page_31"><span class="page">Page 31</span></a>
+lime cannot be positively shown to be connected with the previous
+operation of living beings, there is room for doubt whether this
+salt is not in reality always primarily a product of vital action.
+The phosphatic nodules of the Upper Greensand are erroneously
+called "coprolites," from the belief originally entertained that
+they were the droppings or fossilised excrements of extinct
+animals; and though this is not the case, there can be little
+doubt but that the phosphate of lime which they contain is in
+this instance of organic origin.[5] It appears, in fact, that
+decaying animal matter has a singular power of determining the
+precipitation around it of mineral salts dissolved in water.
+Thus, when any animal bodies are undergoing decay at the bottom
+of the sea, they have a tendency to cause the precipitation
+from the surrounding water of any mineral matters which may be
+dissolved in it; and the organic body thus becomes a centre
+round which the mineral matters in question are deposited in
+the form of a "concretion" or "nodule." The phosphatic nodules
+in question were formed in a sea in which phosphate of lime,
+derived from the destruction of animal skeletons, was held largely
+in solution; and a precipitation of it took place round any body,
+such as a decaying animal substance, which happened to be lying on
+the sea-bottom, and which offered itself as a favourable nucleus.
+In the same way we may explain the formation of the calcareous
+nodules, known as "septaria" or "cement stones," which occur so
+commonly in the London Clay and Kimmeridge Clay, and in which the
+principal ingredient is carbonate of lime. A similar origin is to
+be ascribed to the nodules of clay iron-stone (impure carbonate of
+iron) which occur so abundantly in the shales of the Carboniferous
+series and in other argillaceous deposits; and a parallel modern
+example is to be found in the nodules of manganese, which were
+found by Sir Wyville Thomson, in the Challenger, to be so numerously
+scattered over the floor of the Pacific at great depths. In
+accordance with this mode of origin, it is exceedingly common
+to find in the centre of all these nodules, both old and new,
+some organic body, such as a bone, a shell, or a tooth, which
+acted as the original nucleus of precipitation, and
+<a name="page_32"><span class="page">Page 32</span></a>
+was thus preserved in a shroud of mineral matter.
+Many nodules, it is true, show no such nucleus; but it has been
+affirmed that all of them can be shown, by appropriate
+microscopical investigation, to have been formed round an original
+organic body to begin with (Hawkins Johnson).
+</p>
+
+<p class="footnote">
+[Footnote 4: Apart from the occurrence or phosphate of lime in
+actual beds in the stratified rocks, as in the Laurentian and
+Silurian series, this salt may also occur disseminated through
+the rock, when it can only be detected by chemical analysis. It
+is interesting to note that Dr Hicks has recently proved the
+occurrence of phosphate of lime in this disseminated form in
+rocks as old as the Cambrian, and that in quantity quite equal to
+what is generally found to be present in the later fossiliferous
+rocks. This affords a chemical proof that animal life flourished
+abundantly in the Cambrian seas.]
+</p>
+
+<p class="footnote">
+[Footnote 5: It has been maintained, indeed, that the phosphatic
+nodules so largely worked for agricultural purposes, are in
+themselves actual organic bodies or true fossils. In a few cases
+this admits of demonstration, as it can be shown that the nodule
+is simply an organism (such as a sponge) infiltrated with phosphate
+of lime (Sollas); but there are many other cases in which no actual
+structure has yet been shown to exist, and as to the true origin
+of which it would be hazardous to offer a positive opinion.]
+</p>
+
+<p class="indent">
+The last lime-salt which need be mentioned is <i>gypsum</i>,
+or <i>sulphate of lime</i>. This substance, apart from other
+modes of occurrence, is not uncommonly found interstratified
+with the ordinary sedimentary rocks, in the form of more or less
+irregular beds; and in these cases it has a palæontological
+importance, as occasionally yielding well-preserved fossils. Whilst
+its exact mode of origin is uncertain, it cannot be regarded as
+in itself an organic rock, though clearly the product of chemical
+action. To look at, it is usually a whitish or yellowish-white
+rock, as coarsely crystalline as loaf-sugar, or more so; and
+the microscope shows it to be composed entirely of crystals of
+sulphate of lime.
+</p>
+
+<p class="indent">
+We have seen that the <i>calcareous</i> or lime-containing rocks
+are the most important of the group of organic deposits; whilst
+the <i>siliceous</i> or flint-containing rocks may be regarded as
+the most important, most typical, and most generally distributed
+of the mechanically-formed rocks. We have, however, now briefly
+to consider certain deposits which are more or less completely
+formed of flint; but which, nevertheless, are essentially organic
+in their origin.
+</p>
+
+<p class="indent">
+Flint or silex, hard and intractable as it is, is nevertheless
+capable of solution in water to a certain extent, and even of
+assuming, under certain circumstances, a gelatinous or viscous
+condition. Hence, some hot-springs are impregnated with silica
+to a considerable extent; it is present in small quantity in
+sea-water; and there is reason to believe that a minute proportion
+must very generally be present in all bodies of fresh water as
+well. It is from this silica dissolved in the water that many
+animals and some plants are enabled to construct for themselves
+flinty skeletons; and we find that these animals and plants are and
+have been sufficiently numerous to give rise to very considerable
+deposits of siliceous matter by the mere accumulation of their
+skeletons. Amongst the animals which require special mention in
+this connection are the microscopic organisms which are known
+to the naturalist as <i>Polycystina</i>. These little creatures
+are of the lowest possible grade of organisation, very closely
+related to the animals which we have previously spoken of as
+<i>Foraminifera</i>, but differing in the fact that they secrete
+a shell or skeleton composed of flint instead of lime. The
+<i>Polycystina</i> occur abundantly in our present seas;
+<a name="page_33"><span class="page">Page 33</span></a>
+and their shells are present in some numbers
+in the ooze which is found at great depths in the Atlantic and
+Pacific oceans, being easily recognised by their exquisite
+shape, their glassy transparency, the general presence of longer
+or shorter spines, and the sieve-like perforations in the walls.
+Both in Barbadoes and in the Nicobar islands occur geological
+formations which are composed of the flinty skeletons of these
+microscopic animals; the deposit in the former locality
+attaining a great thickness, and having been long known to
+workers with the microscope under the name of "Barbadoes earth"
+(fig. 15).
+</p>
+
+<p class="indent">
+In addition to flint-producing animals, we have also the great
+group of fresh-water and marine microscopic plants known as
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 266px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig015.jpg" width="258" height="253" alt="Fig. 15" />
+<br />
+Fig. 15.&mdash;Shells of <i>Polycystina</i> from "Barbadoes
+earth;" greatly magnified. (Original.)
+</span>
+
+<span style="width: 266px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig016.jpg" width="258" height="252" alt="Fig. 16" />
+<br />
+Fig 16.&mdash;Cases of Diatoms in the Richmond "Infusorial
+earth;" highly magnified. (Original.)
+</span>
+
+</span>
+
+<i>Diatoms</i>, which likewise secrete a siliceous skeleton, often
+of great beauty. The skeletons of Diatoms are found abundantly at
+the present day in lake-deposits, guano, the silt of estuaries,
+and in the mud which covers many parts of the sea-bottom; they
+have been detected in strata of great age; and in spite of their
+microscopic dimensions, they have not uncommonly accumulated to
+form deposits of great thickness, and of considerable superficial
+extent. Thus the celebrated deposit of "tripoli" ("Polir-schiefer")
+of Bohemia, largely worked as polishing-powder, is composed wholly,
+or almost wholly, of the flinty cases of Diatoms, of which it
+is calculated that no less than forty-one thousand millions go
+to make up a single cubic inch of the stone. Another celebrated
+deposit is the so-called "Infusorial earth" of Richmond in Virginia,
+where there is a stratum in places thirty feet thick, composed
+almost entirely of the microscopic shells of Diatoms.
+</p>
+
+<p class="indent">
+Nodules or layers of <i>flint</i>, or the impure variety of flint
+<a name="page_34"><span class="page">Page 34</span></a>
+known as <i>chert</i>, are found in limestones
+of almost all ages from the Silurian upwards; but they are
+especially abundant in the chalk. When these flints are examined
+in thin and transparent slices under the microscope, or in polished
+sections, they are found to contain an abundance of minute organic
+bodies&mdash;such as <i>Foraminifera</i>, sponge-spicules,
+&amp;c.&mdash;embedded in a siliceous basis. In many instances the
+flint contains larger organisms&mdash;such as a Sponge or a
+Sea-urchin. As the flint has completely surrounded
+and infiltrated the fossils which it contains, it is obvious
+that it must have been deposited from sea-water in a gelatinous
+condition, and subsequently have hardened. That silica is capable
+of assuming this viscous and soluble condition is known; and
+the formation of flint may therefore be regarded as due to the
+separation of silica from the sea-water and its deposition round
+some organic body in a state of chemical change or decay, just as
+nodules of phosphate of lime or carbonate of iron are produced.
+The existence of numerous organic bodies in flint has long been
+known; but it should be added that a recent observer (Mr Hawkins
+Johnson) asserts that the existence of an organic structure can
+be demonstrated by suitable methods of treatment, even in the
+actual matrix or basis of the flint.[6]
+</p>
+
+<p class="footnote">
+[Footnote 6: It has been asserted that the flints of the chalk
+are merely fossil sponges. No explanation of the origin of flint,
+however, can be satisfactory, unless it embraces the origin of
+chert in almost all great limestones from the Silurian upwards,
+as well as the common phenomenon of the silicification of organic
+bodies (such as corals and shells) which are known with certainty
+to have been originally calcareous.]
+</p>
+
+<p class="indent">
+In addition to deposits formed of flint itself, there are other
+siliceous deposits formed by certain <i>silicates</i>, and also of
+organic origin. It has been shown, namely&mdash;by observations
+carried out in our present seas&mdash;that the shells of
+<i>Foraminifera</i> are liable to become completely infiltrated
+by silicates (such as "glauconite," or silicate of iron and
+potash). Should the actual calcareous shell become dissolved
+away subsequent to this infiltration&mdash;as is also liable
+to occur&mdash;then, in place of the shells of the
+<i>Foraminifera</i>, we get a corresponding number of green
+sandy grains of glauconite, each grain being the <i>cast</i>
+of a single shell. It has thus been shown that the green sand
+found covering the sea-bottom in certain localities (as found by
+the Challenger expedition along the line of the Agulhas current)
+is really organic, and is composed of casts of the shells of
+<i>Foraminifera</i>. Long before these observations had been
+made, it had been shown by Professor Ehrenberg that the green
+sands of various geological formations are composed mainly of
+the internal casts of the shells of <i>Foraminifera</i>, and
+<a name="page_35"><span class="page">Page 35</span></a>
+we have thus another and a very
+interesting example how rock-deposits of considerable extent
+and of geological importance can be built up by the operation
+of the minutest living beings.
+</p>
+
+<p class="indent">
+As regards <i>argillaceous</i> deposits, containing <i>alumina</i>
+or <i>clay</i> as their essential ingredient, it cannot be said that
+any of these have been actually shown to be of organic origin. A
+recent observation by Sir Wyville Thomson would, however, render it
+not improbable that some of the great argillaceous accumulations of
+past geological periods may be really organic. This distinguished
+observer, during the cruise of the Challenger, showed that the
+calcareous ooze which has been already spoken of as covering
+large areas of the floor of the Atlantic and Pacific at great
+depths, and which consists almost wholly of the shells of
+<i>Foraminifera</i>, gave place at still greater depths to a
+red ooze consisting of impalpable clayey mud, coloured by oxide
+of iron, and devoid of traces of organic bodies. As the existence
+of this widely-diffused red ooze, in mid-ocean, and at such great
+depths, cannot be explained on the supposition that it is a sediment
+brought down into the sea by rivers, Sir Wyville Thomson came to
+the conclusion that it was probably formed by the action of the
+sea-water upon the shells of <i>Foraminifera</i>. These shells,
+though mainly consisting of lime, also contain a certain proportion
+of alumina, the former being soluble in the carbonic acid dissolved
+in the sea-water, whilst the latter is insoluble. There would
+further appear to be grounds for believing that the solvent power
+of the sea-water over lime is considerably increased at great
+depths. If, therefore, we suppose the shells of <i>Foraminifera</i>
+to be in course of deposition over the floor of the Pacific, at
+certain depths they would remain unchanged, and would accumulate
+to form a calcareous ooze; but at greater depths they would be
+acted upon by the water, their lime would be dissolved out, their
+form would disappear, and we should simply have left the small
+amount of alumina which they previously contained. In process
+of time this alumina would accumulate to form a bed of clay; and
+as this clay had been directly derived from the decomposition
+of the shells of animals, it would be fairly entitled to be
+considered an organic deposit. Though not finally established,
+the hypothesis of Sir Wyville Thomson on this subject is of the
+greatest interest to the palæontologist, as possibly serving to
+explain the occurrence, especially in the older formations, of
+great deposits of argillaceous matter which are entirely destitute
+of traces of life.
+</p>
+
+<p class="indent">
+It only remains, in this connection, to shortly consider the
+rock-deposits in which <i>carbon</i> is found to be present in
+<a name="page_36"><span class="page">Page 36</span></a>
+greater or less quantity. In the great
+majority of cases where rocks are found to contain carbon or
+carbonaceous matter, it can be stated with certainty that this
+substance is of organic origin, though it is not necessarily
+derived from vegetables. Carbon derived from the decomposition
+of animal bodies is not uncommon; though it never occurs in
+such quantity from this source as it may do when it is derived
+from plants. Thus, many limestones are more or less highly
+bituminous; the celebrated siliceous flags or so-called
+"bituminous schists" of Caithness are impregnated with oily
+matter apparently derived from the decomposition of the
+numerous fishes embedded in them; Silurian shales containing
+Graptolites, but destitute of plants, are not uncommonly
+"anthracitic," and contain a small percentage of carbon derived
+from the decay of these zoophytes; whilst the petroleum so largely
+worked in North America has not improbably an animal origin.
+That the fatty compounds present in animal bodies should more or
+less extensively impregnate fossiliferous rock-masses, is only
+what might be expected; but the great bulk of the carbon which
+exists stored up in the earth's crust is derived from plants;
+and the form in which it principally presents itself is that of
+coal. We shall have to speak again, and at greater length, of
+coal, and it is sufficient to say here that all the true coals,
+anthracites, and lignites, are of organic origin, and consist
+principally of the remains of plants in a more or less altered
+condition. The bituminous shales which are found so commonly
+associated with beds of coal also derive their carbon primarily
+from plants; and the same is certainly, or probably, the case
+with similar shales which are known to occur in formations younger
+than the Carboniferous. Lastly, carbon may occur as a conspicuous
+constituent of rock-masses in the form of <i>graphite</i> or
+<i>black-lead</i>. In this form, it occurs in the shape of detached
+scales, of veins or strings, or sometimes of regular layers;[7]
+and there can be little doubt that in many instances it has an
+organic origin, though this is not capable of direct proof. When
+present, at any rate, in quantity, and in the form of layers
+associated with stratified rocks, as is often the case in the
+Laurentian formation, there can be little hesitation in regarding
+it as of vegetable origin, and as an altered coal.
+</p>
+
+<p class="footnote">
+[Footnote 7: In the Huronian formation at Steel River, on the
+north shore of Lake Superior, there exists a bed of carbonaceous
+matter which is regularly interstratified with the surrounding
+rocks, and has a thickness of from 30 to 40 feet. This bed is
+shown by chemical analysis to contain about 50 per cent of carbon,
+partly in the form of graphite, partly in the form of anthracite;
+and there can be little doubt but that it is really a stratum
+of "metamorphic" coal.]
+</p>
+
+<h3>
+<a name="page_37"><span class="page">Page 37</span></a>
+CHAPTER III.</h3>
+
+<p class="subtitle">
+CHRONOLOGICAL SUCCESSION OF THE FOSSILIFEROUS ROCKS.
+</p>
+
+<p class="indent">
+The physical geologist, who deals with rocks simply as rocks,
+and who does not necessarily trouble himself about what fossils
+they may contain, finds that the stratified deposits which form
+so large a portion of the visible part of the earth's crust are
+not promiscuously heaped together, but that they have a certain
+definite arrangement. In each country that he examines, he finds
+that certain groups of strata lie above certain other groups;
+and in comparing different countries with one another, he finds
+that, in the main, the same groups of rocks are always found in the
+same relative position to each other. It is possible, therefore,
+for the physical geologist to arrange the known stratified rocks
+into a successive series of groups, or "formations," having a
+certain definite order. The establishment of this physical order
+amongst the rocks introduces, however, at once the element of
+<i>time</i>, and the physical succession of the strata can be
+converted directly into a historical or <i>chronological</i>
+succession. This is obvious, when we reflect that any bed or
+set of beds of sedimentary origin is clearly and necessarily
+younger than all the strata upon which it rests, and older than
+all those by which it is surmounted.
+</p>
+
+<p class="indent">
+It is possible, then, by an appeal to the rocks alone, to determine
+in each country the general physical succession of the strata, and
+this "stratigraphical" arrangement, when once determined, gives us
+the <i>relative</i> ages of the successive groups. The task,
+however, of the physical geologist in this matter is immensely
+lightened when he calls in palæontology to his aid, and
+studies the evidence of the fossils embedded in the rocks. Not only
+is it thus much easier to determine the order of succession of the
+strata in any given region, but it becomes now for the first time
+possible to compare, with certainty and precision, the order of
+succession in one region with that which exists in other regions
+far distant. The value of fossils as tests of the relative ages
+of the sedimentary rocks depends on the fact that they are not
+indefinitely or promiscuously scattered through the crust of the
+earth,&mdash;as it is conceivable that they might be. On the
+contrary, the first and most firmly established law of
+Palæontology is, that <i>particular kinds of fossils are
+confined to particular rocks</i>, and <i>particular groups of
+fossils are confined to particular groups of rocks</i>.
+<a name="page_38"><span class="page">Page 38</span></a>
+Fossils, then, are distinctive
+of the rocks in which they are found&mdash;much more distinctive,
+in fact, than the mere mineral character of the rock can be, for
+<i>that</i> commonly changes as a formation is traced from one
+region to another, whilst the fossils remain unaltered. It would
+therefore be quite possible for the palæontologist, by an
+appeal to the fossils alone, to arrange the series of sedimentary
+deposits into a pile of strata having a certain definite order.
+Not only would this be possible, but it would be found&mdash;if
+sufficient knowledge had been brought to bear on both
+sides&mdash;that the palæontological arrangement of the
+strata would coincide in its details with the stratigraphical
+or physical arrangement.
+</p>
+
+<p class="indent">
+Happily for science, there is no such division between the
+palæontologist and the physical geologist as here supposed; but
+by the combined researches of the two, it has been found possible
+to divide the entire series of stratified deposits into a number
+of definite <i>rock-groups</i> or <i>formations</i>, which have a
+recognised order of succession, and each of which is characterised
+by possessing an assemblage of organic remains which do not occur
+in association in any other formation. Such an <i>assemblage of
+fossils</i>, characteristic of any given formation, represents
+the <i>life</i> of the particular <i>period</i> in which the
+formation was deposited. In this way the past history of the earth
+becomes divided into a series of successive <i>life-periods</i>,
+each of which corresponds with the deposition of a particular
+<i>formation</i> or group of strata.
+</p>
+
+<p class="indent">
+Whilst particular <i>assemblages</i> of organic forms characterise
+particular <i>groups</i> of rocks, it may be further said that,
+in a general way, each subdivision of each formation has its own
+peculiar fossils, by which it may be recognised by a skilled
+worker in Palæontology. Whenever, for instance, we meet with
+examples of the fossils which are known as <i>Graptolites</i>,
+we may be sure that we are dealing with <i>Silurian</i> rocks
+(leaving out of sight one or two forms doubtfully referred to
+this family). We may, however, go much farther than this with
+perfect safety. If the Graptolites belong to certain genera,
+we may be quite certain that we are dealing with <i>Lower</i>
+Silurian rocks. Furthermore, if certain special forms are present,
+we may be even able to say to what exact subdivision of the Lower
+Silurian series they belong.
+</p>
+
+<p class="indent">
+As regards particular fossils, however, or even particular classes
+of fossils, conclusions of this nature require to be accompanied
+by a tacit but well-understood reservation. So far as
+<a name="page_39"><span class="page">Page 39</span></a>
+our present observation goes, none of the undoubted
+Graptolites have ever been discovered in rocks later than those
+known upon other grounds to be Silurian; but it is possible that
+they might at any time be detected in younger deposits. Similarly,
+the species and genera which we now regard as characteristic of the
+Lower Silurian, may at some future time be found to have survived
+into the Upper Silurian period. We should not forget, therefore,
+in determining the age of strata by palæontological evidence,
+that we are always reasoning upon generalisations which are the
+result of experience alone, and which are liable to be vitiated
+by further and additional discoveries.
+</p>
+
+<p class="indent">
+When the palæontological evidence as to the age of any given
+set of strata is corroborated by the physical evidence, our
+conclusions may be regarded as almost certain; but there are
+certain limitations and fallacies in the palæontological method
+of inquiry which deserve a passing mention. In the first place,
+fossils are not always present in the stratified rocks; many
+aqueous rocks are unfossiliferous, through a thickness of hundreds
+or even thousands of feet of little-altered sediments; and even
+amongst beds which do contain fossils, we often meet with strata
+of many feet or yards in thickness which are wholly destitute
+of any traces of fossils. There are, therefore, to begin with,
+many cases in which there is no palæontological evidence extant
+or available as to the age of a given group of strata. In the
+second place, palæontological observers in different parts of
+the world are liable to give different names to the same fossil,
+and in all parts of the world they are occasionally liable to group
+together different fossils under the same title. Both these sources
+of fallacy require to be guarded against in reasoning as to the age
+of strata from their fossil remains. Thirdly, the mere fact of
+fossils being found in beds which are known by physical evidence
+to be of different ages, has commonly led palæontologists
+to describe them as different species. Thus, the same fossil,
+occurring in successive groups of strata, and with the merely
+trivial and varietal differences due to the gradual change in its
+environment, has been repeatedly described as a distinct species,
+with a distinct name, in every bed in which it was found. We know,
+however, that many fossils range vertically through many groups
+of strata, and there are some which even pass through several
+formations. The mere fact of a difference of physical position
+ought never to be taken into account at all in considering and
+determining the true affinities of a fossil. Fourthly, the results
+of experience, instead of being an assistance, are sometimes
+liable to operate as a source of error. When once,
+<a name="page_40"><span class="page">Page 40</span></a>
+namely, a generalisation has been established
+that certain fossils occur in strata of a certain age,
+palæontologists are apt to infer that <i>all</i> beds
+containing similar fossils must be of the same age. There is a
+presumption, of course, that this inference would be correct;
+but it is not a conclusion resting upon absolute necessity, and
+there might be physical evidence to disprove it. Fifthly, the
+physical geologist may lead the palæontologist astray by
+asserting that the physical evidence as to the age and position
+of a given group of beds is clear and unequivocal, when such
+evidence may be, in reality, very slight and doubtful. In this
+way, the observer may be readily led into wrong conclusions as
+to the nature of the organic remains&mdash;often obscure and
+fragmentary&mdash;which it is his business to examine, or he may
+be led erroneously to think that previous generalisations as to
+the age of certain kinds of fossils are premature and incorrect.
+Lastly, there are cases in which, owing to the limited exposure
+of the beds, to their being merely of local development, or to
+other causes, the physical evidence as to the age of a given
+group of strata may be entirely uncertain and unreliable, and
+in which, therefore, the observer has to rely wholly upon the
+fossils which he may meet with.
+</p>
+
+<p class="indent">
+In spite of the above limitations and fallacies, there can be
+no doubt as to the enormous value of palæontology in enabling
+us to work out the historical succession of the sedimentary rocks.
+It may even be said that in any case where there should appear
+to be a clear and decisive discordance between the physical and
+the palæontological evidence as to the age of a given series
+of beds, it is the former that is to be distrusted rather than
+the latter. The records of geological science contain not a few
+cases in which apparently clear physical evidence of superposition
+has been demonstrated to have been wrongly interpreted; but the
+evidence of palæontology, when in any way sufficient, has
+rarely been upset by subsequent investigations. Should we find
+strata containing plants of the Coal-measures apparently resting
+upon other strata with Ammonites and Belemnites, we may be sure
+that the physical evidence is delusive; and though the above is an
+extreme case, the presumption in all such instances is rather that
+the physical succession has been misunderstood or misconstrued,
+than that there has been a subversion of the recognised succession
+of life-forms.
+</p>
+
+<p class="indent">
+We have seen, then, that as the collective result of observations
+made upon the superposition of rocks in different localities, from
+their mineral characters, and from their included
+<a name="page_41"><span class="page">Page 41</span></a>
+fossils, geologists have been able to divide the entire
+stratified series into a number of different divisions or
+formations, each characterised by a <i>general</i> uniformity of
+mineral composition, and by a special and peculiar <i>assemblage</i>
+of organic forms. Each of these primary groups is in turn divided
+into a series of smaller divisions, characterised and distinguished
+in the same way. It is not pretended for a moment that all these
+primary rock-groups can anywhere be seen surmounting one another
+regularly.[8] There is no region upon the earth where all the
+stratified formations can be seen together; and, even when most
+of them occur in the same country, they can nowhere be seen all
+succeeding each other in their regular and uninterrupted succession.
+The reason of this is obvious. There are many places&mdash;to take
+a single example&mdash;where one may see the the Silurian rocks,
+the Devonian, and the Carboniferous rocks succeeding one another
+regularly, and in their proper order. This is because the
+particular region where this occurs was always submerged beneath
+the sea while these formations were being deposited. There are,
+however, many more localities in which one would find the
+Carboniferous rocks resting unconformably upon the Silurians
+without the intervention of any strata which could be referred
+to the Devonian period. This might arise from one of two causes:
+1. The Silurians might have been elevated above the sea
+immediately after their deposition, so as to form dry land
+during the whole of the Devonian period, in which case, of course,
+no strata of the latter age could possibly be deposited in that
+area. 2. The Devonian might have been deposited upon the Silurian,
+and then the whole might have been elevated above the sea, and
+subjected to an amount of denudation sufficient to remove the
+Devonian strata entirely. In this case, when the land was again
+submerged, the Carboniferous rocks, or any younger formation,
+might be deposited directly upon Silurian strata. From one or
+other of these causes, then, or from subsequent disturbances
+and denudations, it happens that we can
+<a name="page_42"><span class="page">Page 42</span></a>
+rarely find many of the primary formations following one another
+consecutively and in their regular order.
+</p>
+
+<p class="footnote">
+[Footnote 8: As we have every reason to believe that dry land
+and sea have existed, at any rate from the commencement of the
+Laurentian period to the present day, it is quite obvious that
+no one of the great formations can ever, under any circumstances,
+have extended over the entire globe. In other words, no one of
+the formations can ever have had a greater geographical extent
+than that of the seas of the period in which the formation was
+deposited. Nor is there any reason for thinking that the proportion
+of dry land to ocean has ever been materially different to what
+it is at present, however greatly the areas of sea and land may
+have changed as regards their place. It follows from the above,
+that there is no sufficient basis for the view that the crust of
+the earth is composed of a succession of concentric layers, like
+the coats of an onion, each layer representing one formation.]
+</p>
+
+<p class="indent">
+In no case, however, do we ever find the Devonian resting upon
+the Carboniferous, or the Silurian rocks reposing on the
+Devonian. We have therefore, by a comparison of many different
+areas, an established order of succession of the stratified
+formations, as shown in the subjoined ideal section of the crust
+of the earth (fig. 17).
+</p>
+
+<p class="indent">
+The main subdivisions of the stratified rocks are known by the
+following names:&mdash;
+</p>
+
+<div class="center">
+<table summary="" style="">
+ <tr><td class="right">1.</td>
+  <td colspan="2" class="left">Laurentian.</td></tr>
+ <tr><td class="right">2.</td>
+  <td colspan="2" class="left">Cambrian (with
+   Huronian?).</td></tr>
+ <tr><td class="right">3.</td>
+  <td colspan="2" class="left">Silurian.</td></tr>
+ <tr><td class="right">4.</td>
+  <td colspan="2" class="left">Devonian or Old Red
+   Sandstone.</td></tr>
+ <tr><td class="right">5.</td>
+  <td colspan="2" class="left">Carboniferous.</td></tr>
+ <tr><td class="right">6.</td>
+  <td class="left">Permian</td>
+  <td class="left" rowspan="2"><span class="big">}</span>
+   &nbsp;New&nbsp;Red&nbsp;Sandstone.</td></tr>
+ <tr><td class="right">7.</td>
+  <td colspan="2" class="left">Triassic</td></tr>
+ <tr><td class="right">8.</td>
+  <td colspan="2" class="left">Jurassic or Oolitic.</td></tr>
+ <tr><td class="right">9.</td>
+  <td colspan="2" class="left">Cretaceous.</td></tr>
+ <tr><td class="right">10.</td>
+  <td colspan="2" class="left">Eocene.</td></tr>
+ <tr><td class="right">11.</td>
+  <td colspan="2" class="left">Miocene.</td></tr>
+ <tr><td class="right">12.</td>
+  <td colspan="2" class="left">Pliocene.</td></tr>
+ <tr><td class="right">13.</td>
+  <td colspan="2" class="left">Post-tertiary.</td></tr>
+</table>
+</div>
+
+<p>&nbsp;</p>
+
+<div class="center">
+<table summary="" style="">
+<tr><td class="center"><span class="image">
+<a name="page_43"><span class="page">Page 43</span></a>
+IDEAL SECTION OF THE CRUST OF THE EARTH.
+</span></td></tr>
+<tr><td class="center"><span class="image">Fig. 17.
+</span></td></tr>
+<tr><td>
+<img src="images/fig017.jpg" width="518" height="848" alt="Fig. 17" />
+</td></tr>
+</table>
+</div>
+
+<p class="indent">
+<a name="page_44"><span class="page">Page 44</span></a>
+Of these primary rock divisions, the Laurentian, Cambrian, Silurian,
+Devonian, Carboniferous, and Permian are collectively grouped
+together under the name of the Primary or <i>Palœozoic</i>
+rocks (Gr. <i>palaios</i>, ancient; <i>zoe</i>, life). Not only do
+they constitute the oldest stratified accumulations, but from the
+extreme divergence between their animals and plants and those now
+in existence, they may appropriately be considered as belonging to
+an "Old-Life" period of the world's history. The Triassic, Jurassic,
+and Cretaceous systems are grouped together as the
+<i>Secondary</i> or <i>Mesozoic</i> formations (Gr. <i>mesos</i>,
+intermediate; <i>zoe</i>, life); the organic remains of this
+"Middle-Life" period being, on the whole, intermediate in their
+characters between those of the palæozoic epoch and those of
+more modern strata. Lastly, the Eocene, Miocene, and Pliocene
+formations are grouped together as the <i>Tertiary</i> or
+<i>Kainozoic</i> rocks (Gr. <i>kainos</i>, new; <i>zoe</i>, life);
+because they constitute a "New-Life" period, in which the organic
+remains approximate in character to those now existing upon the
+globe. The so-called <i>Post-Tertiary</i> deposits are placed
+with the Kainozoic, or may be considered as forming a separate
+<i>Quaternary</i> system.
+</p>
+
+<h3>CHAPTER IV.</h3>
+
+<p class="subtitle">
+THE BREAKS IN THE GEOLOGICAL AND PALÆONTOLOGICAL
+RECORD.
+</p>
+
+<p class="indent">
+The term "contemporaneous" is usually applied by geologists to
+groups of strata in different regions which contain the same
+fossils, or an assemblage of fossils in which many identical
+forms are present. That is to say, beds which contain identical,
+or nearly identical, fossils, however widely separated they may
+be from one another in point of actual distance, are ordinarily
+believed to have been deposited during the same period of the
+earth's history. This belief, indeed, constitutes the keystone
+of the entire system of determining the age of strata by their
+fossil contents; and if we take the word "contemporaneous" in a
+general and strictly geological sense, this belief can be accepted
+as proved beyond denial. We must, however, guard ourselves against
+too literal an interpretation of the word "contemporaneous," and
+we must bear in mind the enormously-prolonged periods of time with
+which the geologist has to deal. When we say that two groups of
+<a name="page_45"><span class="page">Page 45</span></a>
+strata in different regions are "contemporaneous," we simply mean
+that they were formed during the same geological period, and
+perhaps at different stages of that period, and we do not mean to
+imply that they were formed at precisely the same instant of time.
+</p>
+
+<p class="indent">
+A moment's consideration will show us that it is only in the
+former sense that we can properly speak of strata being
+"contemporaneous;" and that, in point of fact, beds containing
+the same fossils, if occurring in widely distant areas, can hardly
+be "contemporaneous" in any literal sense; but that the very
+identity of their fossils is proof that they were deposited one
+after the other. If we find strata containing identical fossils
+within the limits of a single geographical region&mdash;say in
+Europe&mdash;then there is a reasonable probability that these beds
+are strictly contemporaneous, in the sense that they were deposited
+at the same time. There is a reasonable probability of this,
+because there is no improbability involved in the idea of an
+ocean occupying the whole area of Europe, and peopled throughout
+by many of the same species of marine animals. At the present
+day, for example, many identical species of animals are found
+living on the western coasts of Britain and the eastern coasts
+of North America, and beds now in course of deposition off the
+shores of Ireland and the seaboard of the state of New York would
+necessarily contain many of the same fossils. Such beds would be
+both literally and geologically contemporaneous; but the case is
+different if the distance between the areas where the strata occur
+be greatly increased. We find, for example, beds containing identical
+fossils (the Quebec or Skiddaw beds) in Sweden, in the north of
+England, in Canada, and in Australia. Now, if all these beds were
+contemporaneous, in the literal sense of the term, we should have
+to suppose that the ocean at one time extended uninterruptedly
+between all these points, and was peopled throughout the vast area
+thus indicated by many of the same animals. Nothing, however,
+that we see at the present day would justify us in imagining an
+ocean of such enormous extent, and at the same time so uniform
+in its depth, temperature, and other conditions of marine life,
+as to allow the same animals to flourish in it from end to end;
+and the example chosen is only one of a long and ever-recurring
+series. It is therefore much more reasonable to explain this,
+and all similar cases, as owing to the <i>migration</i> of the
+fauna, in whole or in part, from one marine area to another.
+Thus, we may suppose an ocean to cover what is now the European
+area, and to be peopled by certain species of animals. Beds of
+sediment&mdash;clay, sands, and limestones&mdash;will be deposited
+over the sea-bottom, and
+<a name="page_46"><span class="page">Page 46</span></a>
+will entomb the
+remains of the animals as fossils. After this has lasted for a
+certain length of time, the European area may undergo elevation,
+or may become otherwise unsuitable for the perpetuation of its
+fauna; the result of which would be that some or all of the
+marine animals of the area would migrate to some more suitable
+region. Sediments would then be accumulated in the new area to
+which they had betaken themselves, and they would then appear,
+for the second time, as fossils in a set of beds widely
+separated from Europe. The second set of beds would, however,
+obviously not be strictly or literally contemporaneous with the
+first, but would be separated from them by the period of time
+required for the migration of the animals from the one area
+into the other. It is only in a wide and comprehensive sense
+that such strata can be said to be contemporaneous.
+</p>
+
+<p class="indent">
+It is impossible to enter further into this subject here; but it
+may be taken as certain that beds in widely remote geographical
+areas can only come to contain the same fossils by reason of a
+migration having taken place of the animals of the one area to
+the other. That such migrations can and do take place is quite
+certain, and this is a much more reasonable explanation of the
+observed facts than the hypothesis that in former periods the
+conditions of life were much more uniform than they are at present,
+and that, consequently, the same organisms were able to range over
+the entire globe at the same time. It need only be added, that
+taking the evidence of the present as explaining the phenomena
+of the past&mdash;the only safe method of reasoning in geological
+matters&mdash;we have abundant proof that deposits which <i>are</i>
+actually contemporaneous, in the strict sense of the term, <i>do
+not contain the same fossils, if far removed from one another in
+point of distance</i>. Thus, deposits of various kinds are now
+in process of formation in our existing seas, as, for example, in
+the Arctic Ocean, the Atlantic, and the Pacific, and many of these
+deposits are known to us by actual examination and observation
+with the sounding-lead and dredge. But it is hardly necessary to
+add that the animal remains contained in these deposits&mdash;the
+fossils of some future period&mdash;instead of being identical, are
+widely different from one another in their characters.
+</p>
+
+<p class="indent">
+We have seen, then, that the entire stratified series is capable of
+subdivision into a number of definite rock-groups or "formations,"
+each possessing a peculiar and characteristic assemblage of fossils,
+representing the "life" of the "period" in which the formation
+was deposited. We have still to inquire shortly how it came to
+pass that two successive formations <i>should</i>
+<a name="page_47"><span class="page">Page 47</span></a>
+thus be broadly distinguished by their life-forms, and why
+they should not rather possess at any rate a majority of identical
+fossils. It was originally supposed that this could be explained by
+the hypothesis that the close of each formation was accompanied by
+a general destruction of all the living beings of the period, and
+that the commencement of each new formation was signalised by the
+creation of a number of brand-new organisms, destined to figure
+as the characteristic fossils of the same. This theory, however,
+ignores the fact that each formation&mdash;as to which we have
+any sufficient evidence&mdash;contains a few, at least, of the
+life-forms which existed in the preceding period; and it invokes
+forces and processes of which we know nothing, and for the supposed
+action of which we cannot account. The problem is an undeniably
+difficult one, and it will not be possible here to give more than
+a mere outline of the modern views upon the subject. Without
+entering into the at present inscrutable question as to the manner
+in which new life-forms are introduced upon the earth, it may be
+stated that almost all modern geologists hold that the living beings
+of any given formation are in the main modified forms of others
+which have preceded them. It is not believed that any general or
+universal destruction of life took place at the termination of
+each geological period, or that a general introduction of new
+forms took place at the commencement of a new period. It is, on
+the contrary, believed that the animals and plants of any given
+period are for the most part (or exclusively) the lineal but
+modified descendants of the animals and plants of the immediately
+preceding period, and that some of them, at any rate, are
+continued into the next succeeding period, either unchanged, or
+so far altered as to appear as new species. To discuss these
+views in detail would lead us altogether too far, but there is
+one very obvious consideration which may advantageously receive
+some attention. It is obvious, namely, that the great
+discordance which is found to subsist between the animal life of
+any given formation and that of the next succeeding formation,
+and which no one denies, would be a fatal blow to the views just
+alluded to, unless admitting of some satisfactory explanation.
+Nor is this discordance one purely of life-forms, for there is
+often a physical break in the successions of strata as well.
+Let us therefore briefly consider how far these interruptions
+and breaks in the geological and palæontological record
+can be accounted for, and still allow us to believe in some
+theory of continuity as opposed to the doctrine of intermittent
+and occasional action.
+</p>
+
+<p class="indent">
+<a name="page_48"><span class="page">Page 48</span></a>
+In the first place, it is perfectly clear that if we admit the
+conception above mentioned of a continuity of life from the
+Laurentian period to the present day, we could never <i>prove</i>
+our view to be correct, unless we could produce in evidence
+fossil examples of <i>all</i> the kinds of animals and plants
+that have lived and died during that period. In order to do
+this, we should require, to begin with, to have access to an
+absolutely unbroken and perfect succession of all the deposits
+which have ever been laid down since the beginning. If, however,
+we ask the physical geologist if he is in possession of any such
+uninterrupted series, he will at once answer in the negative.
+So far from the geological series being a perfect one, it is
+interrupted by numerous gaps of unknown length, many of which we
+can never expect to fill up. Nor are the proofs of this far to
+seek. Apart from the facts that we have hitherto examined only
+a limited portion of the dry land, that nearly two-thirds of
+the entire area of the globe is inaccessible to geological
+investigation in consequence of its being covered by the sea,
+that many deposits can be shown to have been more or less
+completely destroyed subsequent to their deposition, and that
+there may be many areas in which living beings exist where no
+rock is in process of formation, we have the broad fact that
+rock-deposition only goes on to any extent in water, and that
+the earth must have always consisted partly of dry land and
+partly of water&mdash;at any rate, so far as any period of
+which we have geological knowledge is concerned. There
+<i>must</i>, therefore, always have existed, at some part or
+another of the earth's surface, areas where no deposition of
+rock was going on, and the proof of this is to be found in the
+well-known phenomenon of "<i>unconformability</i>." Whenever,
+namely, deposition of sediment is continuously going on within
+the limits of a single ocean, the beds which are laid down succeed
+one another in uninterrupted and regular sequence. Such beds are
+said to be "conformable," and there are many rock-groups known
+where one may pass through fifteen or twenty thousand feet of strata
+without a break&mdash;indicating that the beds had been deposited
+in an area which remained continuously covered by the sea. On
+the other hand, we commonly find that there is no such regular
+succession when we pass from one great formation to another, but
+that, on the contrary, the younger formation rests "unconformably,"
+as it is called, either upon the formation immediately preceding
+it in point of time, or upon some still older one. The essential
+physical feature of this unconformability is that the beds of the
+younger formation rest upon a worn and eroded surface formed by the
+<a name="page_49"><span class="page">Page 49</span></a>
+beds of the older series (fig. 18); and a moment's
+consideration will show us what this indicates. It indicates,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 528px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig018.jpg" width="520" height="253" alt="Fig. 18" />
+<br />
+Fig. 18.&mdash;Section showing strata of Tertiary age (<i>a</i>)
+resting upon a worn and eroded surface of White Chalk
+(<i>b</i>), the stratification of which is marked by lines of
+flint.
+</span>
+</span>
+
+beyond the possibility of misconception, that there was an interval
+between the deposition of the older series and that of the newer
+series of strata; and that during this interval the older beds
+were raised above the sea-level, so as to form dry land, and were
+subsequently depressed again beneath the waters, to receive upon
+their worn and wasted upper surface the sediments of the later
+group. During the interval thus indicated, the deposition of rock
+must of necessity have been proceeding more or less actively
+in other areas. Every unconformity, therefore, indicates that
+at the spot where it occurs, a more or less extensive series
+of beds must be actually missing; and though we may sometimes
+be able to point to these missing strata in other areas, there
+yet remains a number of unconformities for which we cannot at
+present supply the deficiency even in a partial manner.
+</p>
+
+<p class="indent">
+It follows from the above that the series of stratified deposits
+is to a greater or less extent irremediably imperfect; and in
+this imperfection we have one great cause why we can never obtain
+a perfect series of all the animals and plants that have lived
+upon the globe. Wherever one of these great physical gaps occurs,
+we find, as we might expect, a corresponding break in the series
+of life-forms. In other words, whenever we find two formations
+to be unconformable, we shall always find at the same time that
+there is a great difference in their fossils, and that many of
+the fossils of the older formation do not survive into the newer,
+whilst many of those in the newer are not known to occur in the
+older. The cause of this is, obviously,
+<a name="page_50"><span class="page">Page 50</span></a>
+that the lapse of time, indicated by the unconformability, has
+been sufficiently great to allow of the dying out or modification
+of many of the older forms of life, and the introduction of new
+ones by immigration.
+</p>
+
+<p class="indent">
+Apart, however, altogether, from these great physical breaks
+and their corresponding breaks in life, there are other reasons
+why we can never become more than partially acquainted with the
+former denizens of the globe. Foremost amongst these is the fact
+that an enormous number of animals possess no hard parts of the
+nature of a skeleton, and are therefore incapable, under any
+ordinary circumstances, of leaving behind them any traces of
+their existence. It is true that there are cases in which animals
+in themselves completely soft-bodied are nevertheless able to leave
+marks by which their former presence can be detected: Thus every
+geologist is familiar with the winding and twisting "trails" formed
+on the surface of the strata by sea-worms; and the impressions
+left by the stranded carcases of Jelly-fishes on the fine-grained
+lithographic slates of Solenhofen supply us with an example of how
+a creature which is little more than "organised sea-water" may
+still make an abiding mark upon the sands of time. As a general
+rule, however, animals which have no skeletons are incapable of
+being preserved as fossils, and hence there must always have
+been a vast number of different kinds of marine animals of which
+we have absolutely no record whatever. Again, almost all the
+fossiliferous rocks have been laid down in water; and it is a
+necessary result of this that the great majority of fossils are
+the remains of aquatic animals. The remains of air-breathing
+animals, whether of the inhabitants of the land or of the air
+itself, are comparatively rare as fossils, and the record of
+the past existence of these is much more imperfect than is the
+case with animals living in water. Moreover, the fossiliferous
+deposits are not only almost exclusively aqueous formations, but
+the great majority are marine, and only a comparatively small
+number have been formed by lakes and rivers. It follows from the
+foregoing that the palæontological record is fullest and most
+complete so far as sea-animals are concerned, though even here we
+find enormous gaps, owing to the absence of hard structures in
+many great groups; of animals inhabiting fresh waters our knowledge
+is rendered still further incomplete by the small proportion
+that fluviatile and lacustrine deposits bear to marine; whilst
+we have only a fragmentary acquaintance with the air-breathing
+animals which inhabited the earth during past ages.
+</p>
+
+<p class="indent">
+Lastly, the imperfection of the palæontological record, due
+<a name="page_51"><span class="page">Page 51</span></a>
+to the causes above enumerated, is greatly aggravated, especially
+as regards the earlier portion of the earth's history, by the fact
+that many rocks which contained fossils when deposited have since
+been rendered barren of organic remains. The principal cause of
+this common phenomenon is what is known as "metamorphism"&mdash;that
+is, the subjection of the rock to a sufficient amount of heat to
+cause a rearrangement of its particles. When at all of a pronounced
+character, the result of metamorphic action is invariably the
+obliteration of any fossils which might have been originally
+present in the rock. Metamorphism may affect rocks of any age,
+though naturally more prevalent in the older rocks, and to this
+cause must be set down an irreparable loss of much fossil evidence.
+The most striking example which is to be found of this is the great
+Laurentian series, which comprises some 30,000 feet of
+highly-metamorphosed sediments, but which, with one not wholly
+undisputed exception, has as yet yielded no remains of living
+beings, though there is strong evidence of the former existence
+in it of fossils.
+</p>
+
+<p class="indent">
+Upon the whole, then, we cannot doubt that the earth's crust, so
+far as yet deciphered by us, presents us with but a very imperfect
+record of the past. Whether the known and admitted imperfections
+of the geological and palæontological records are sufficiently
+serious to account satisfactorily for the deficiency of direct
+evidence recognisable in some modern hypotheses, may be a matter
+of individual opinion. There can, however, be little doubt that
+they are sufficiently extensive to throw the balance of evidence
+decisively in favour of some theory of <i>continuity</i>, as
+opposed to any theory of intermittent and occasional action. The
+apparent breaks which divide the great series of the stratified
+rocks into a number of isolated formations, are not marks of mighty
+and general convulsions of nature, but are simply indications of
+the imperfection of our knowledge. Never, in all probability,
+shall we be able to point to a complete series of deposits, or a
+complete succession of life linking one great geological period
+to another. Nevertheless, we may well feel sure that such deposits
+and such an unbroken succession must have existed at one time.
+We are compelled to believe that nowhere in the long series of
+the fossiliferous rocks has there been a total break, but that
+there must have been a complete continuity of life, and a more
+or less complete continuity of sedimentation, from the Laurentian
+period to the present day. One generation hands on the lamp of
+life to the next, and each system of rocks is the direct offspring
+of those which preceded it in time. Though there
+<a name="page_52"><span class="page">Page 52</span></a>
+has not been continuity in any given area, still the
+geological chain could never have been snapped at one point, and
+taken up again at a totally different one. Thus we arrive at the
+conviction that <i>continuity</i> is the fundamental law of
+geology, as it is of the other sciences, and that the lines of
+demarcation between the great formations are but gaps in our own
+knowledge.
+</p>
+
+<h3>CHAPTER V.</h3>
+
+<p class="subtitle">
+CONCLUSIONS TO BE DRAWN FROM FOSSILS.
+</p>
+
+<p class="indent">
+We have already seen that geologists have been led by the study
+of fossils to the all-important generalisation that the vast
+series of the Fossiliferous or Sedimentary Rocks may be divided
+into a number of definite groups or "formations," each of which is
+characterised by its organic remains. It may simply be repeated here
+that these formations are not properly and strictly characterised
+by the occurrence in them of any one particular fossil. It may be
+that a formation contains some particular fossil or fossils not
+occurring out of that formation, and that in this way an observer
+may identify a given group with tolerable certainty. It very
+often happens, indeed, that some particular stratum, or sub-group
+of a series, contains peculiar fossils, by which its existence
+may be determined in various localities. As before remarked,
+however, the great formations are characterised properly by the
+association of certain fossils, by the predominance of certain
+families or orders, or by an <i>assemblage</i> of fossil remains
+representing the "life" of the period in which the formation
+was deposited.
+</p>
+
+<p class="indent">
+Fossils, then, enable us to determine the <i>age</i> of the deposits
+in which they occur. Fossils further enable us to come to very
+important conclusions as to the mode in which the fossiliferous
+bed was deposited, and thus as to the condition of the particular
+district or region occupied by the fossiliferous bed at the time
+of the formation of the latter. If, in the first place, the bed
+contain the remains of animals such as now inhabit rivers, we
+know that it is "fluviatile" in its origin, and that it must at
+one time have either formed an actual riverbed, or been deposited
+by the overflowing of an ancient stream. Secondly, if the bed
+contain the remains of shellfish, minute crustaceans, or fish,
+such as now inhabit lakes,
+<a name="page_53"><span class="page">Page 53</span></a>
+we know that it is "lacustrine," and was deposited beneath the
+waters of a former lake. Thirdly, if the bed contain the remains
+of animals such as now people the ocean, we know that it is
+"marine" in its origin, and that it is a fragment of an old
+sea-bottom.
+</p>
+
+<p class="indent">
+We can, however, often determine the conditions under which a bed
+was deposited with greater accuracy than this. If, for example, the
+fossils are of kinds resembling the marine animals now inhabiting
+shallow waters, if they are accompanied by the detached relics
+of terrestrial organisms, or if they are partially rolled and
+broken, we may conclude that the fossiliferous deposit was laid
+down in a shallow sea, in the immediate vicinity of a coast-line,
+or as an actual shore-deposit. If, again, the remains are those
+of animals such as now live in the deeper parts of the ocean,
+and there is a very sparing intermixture of extraneous fossils
+(such as the bones of birds or quadrupeds, or the remains of
+plants), we may presume that the deposit is one of deep water.
+In other cases, we may find, scattered through the rock, and
+still in their natural position, the valves of shells such as
+we know at the present day as living buried in the sand or mud
+of the sea-shore or of estuaries. In other cases, the bed may
+obviously have been an ancient coral-reef, or an accumulation of
+social shells, like Oysters. Lastly, if we find the deposit to
+contain the remains of marine shells, but that these are dwarfed
+of their fair proportions and distorted in figure, we may conclude
+that it was laid down in a brackish sea, such as the Baltic, in
+which the proper saltness was wanting, owing to its receiving
+an excessive supply of fresh water.
+</p>
+
+<p class="indent">
+In the preceding, we have been dealing simply with the remains
+of aquatic animals, and we have seen that certain conclusions
+can be accurately reached by an examination of these. As regards
+the determination of the conditions of deposition from the remains
+of aerial and terrestrial animals, or from plants, there is not
+such an absolute certainty. The remains of land-animals would,
+of course, occur in "sub-aerial" deposits&mdash;that is, in beds,
+like blown sand, accumulated upon the land. Most of the remains
+of land-animals, however, are found in deposits which have been
+laid down in water, and they owe their present position to the
+fact that their former owners were drowned in rivers or lakes,
+or carried out to sea by streams. Birds, Flying Reptiles, and
+Flying Mammals might also similarly find their way into aqueous
+deposits; but it is to be remembered that many birds and mammals
+habitually spend a great part of their time in the water, and
+that these might therefore be naturally expected to present
+themselves as fossils in
+<a name="page_54"><span class="page">Page 54</span></a>
+Sedimentary Rocks. Plants, again, even when undoubtedly such as
+must have grown on land, do not prove that the bed in which they
+occur was formed on land. Many of the remains of plants known to
+us are extraneous to the bed in which they are now found, having
+reached their present site by falling into lakes or rivers, or
+being carried out to sea by floods or gales of wind. There are,
+however, many cases in which plants have undoubtedly grown on
+the very spot where we now find them. Thus it is now generally
+admitted that the great coal-fields of the Carboniferous age
+are the result of the growth <i>in situ</i>
+of the plants which compose coal, and that these grew on vast
+
+<span style="float: left; margin: 4px; width: 284px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig019.jpg" width="276" height="429" alt="Fig. 19" />
+<br />
+Fig. 19.&mdash;Erect Tree containing Reptilian remains.
+Coal-measures, Nova Scotia. (After Dawson.)
+</span>
+
+marshy or partially submerged tracts of level alluvial land. We
+have, however, distinct evidence of old land-surfaces, both in
+the Coal-measures and in other cases (as, for instance, in the
+well-known "dirt-bed" of the Purbeck series). When, for example,
+we find the erect stumps of trees standing at right angles to
+the surrounding strata, we know that the surface through which
+these send their roots was at one time the surface of the dry
+land, or, in other words, was an ancient soil (fig. 19).
+</p>
+
+<p class="indent">
+In many cases fossils enable us to come to important conclusions
+as to the climate of the period in which they lived but only a
+few instances of this can be here adduced. As fossils in the
+majority of instances are the remains of marine animals, it is
+mostly the temperature of the sea which can alone be determined
+in this way; and it is important to remember that, owing to the
+existence of heated currents, the marine climate of a given area
+does not necessarily imply a correspondingly warm climate in
+the neighbouring land. Land-climates can only be determined by
+the remains of land-animals or land-plants, and these are
+comparatively rare as fossils. It is also important to remember
+that all conclusions on this
+<a name="page_55"><span class="page">Page 55</span></a>
+head are really based upon the present distribution of animal
+and vegetable life on the globe, and are therefore liable to be
+vitiated by the following considerations:&mdash;
+</p>
+
+<p class="indent">
+<i>a</i>. Most fossils are extinct, and it is not certain that
+the habits and requirements of any extinct animal were exactly
+similar to those of its nearest living relative.
+</p>
+
+<p class="indent">
+<i>b</i>. When we get very far back in time, we meet with groups
+of organisms so unlike anything we know at the present day as to
+render all conjectures as to climate founded upon their supposed
+habits more or less uncertain and unsafe.
+</p>
+
+<p class="indent">
+<i>c</i>. In the case of marine animals, we are as yet very far
+from knowing the exact limits of distribution of many species within
+our present seas; so that conclusions drawn from living forms as
+to extinct species are apt to prove incorrect. For instance, it
+has recently been shown that many shells formerly believed to
+be confined to the Arctic Seas have, by reason of the extension
+of Polar currents, a wide range to the south; and this has thrown
+doubt upon the conclusions drawn from fossil shells as to the
+Arctic conditions under which certain beds were supposed to have
+been deposited.
+</p>
+
+<p class="indent">
+<i>d</i>. The distribution of animals at the present day is certainly
+dependent upon other conditions beside climate alone; and the causes
+which now limit the range of given animals are certainly such as
+belong to the existing order of things. But the establishment of
+the present order of things does not date back in many cases to
+the introduction of the present species of animals. Even in the
+case, therefore, of existing species of animals, it can often
+be shown that the past distribution of the species was different
+formerly to what it is now, not necessarily because the climate
+has changed, but because of the alteration of other conditions
+essential to the life of the species or conducing to its extension.
+</p>
+
+<p class="indent">
+Still, we are in many cases able to draw completely reliable
+conclusions as to the climate of a given geological period, by
+an examination of the fossils belonging to that period. Among
+the more striking examples of how the past climate of a region
+may be deduced from the study of the organic remains contained in
+its rocks, the following may be mentioned: It has been shown that
+in Eocene times, or at the commencement of the Tertiary period,
+the climate of what is now Western Europe was of a tropical or
+sub-tropical character. Thus the Eocene beds are found to contain
+the remains of shells such as now inhabit tropical seas, as, for
+example, Cowries and Volutes; and with these are the fruits of
+palms, and the remains of other tropical plants. It has been shown,
+<a name="page_56"><span class="page">Page 56</span></a>
+again, that in Miocene times, or
+about the middle of the Tertiary period, Central Europe was
+peopled with a luxuriant flora resembling that of the warmer
+parts of the United States, and leading to the conclusion that
+the mean annual temperature must have been at least 30&deg;
+hotter than it is at present. It has been shown that, at the
+same time, Greenland, now buried beneath a vast ice-shroud, was
+warm enough to support a large number of trees, shrubs, and other
+plants, such as inhabit temperate regions of the globe. Lastly,
+it has been shown upon physical as well as palæontological
+evidence, that the greater part of the North Temperate Zone, at
+a comparatively recent geological period, has been visited with
+all the rigours of an Arctic climate, resembling that of
+Greenland at the present day. This is indicated by the occurrence
+of Arctic shells in the superficial deposits of this period,
+whilst the Musk-ox and the Reindeer roamed far south of their
+present limits.
+</p>
+
+<p class="indent">
+Lastly, it was from the study of fossils that geologists learnt
+originally to comprehend a fact which may be regarded as of cardinal
+importance in all modern geological theories and
+speculations&mdash;namely, that the crust of the earth is liable
+to local elevations and subsidences. For long after the remains of
+shells and other marine animals were for the first time observed
+in the solid rocks forming the dry land, and at great heights
+above the sea-level, attempts were made to explain this almost
+unintelligible phenomenon upon the hypothesis that the fossils in
+question were not really the objects they represented, but were
+in truth mere <i>lusus naturœ</i>, due to some "plastic virtue
+latent in the earth." The common-sense of scientific men, however,
+soon rejected this idea, and it was agreed by universal consent
+that these bodies really were remains of animals which formerly
+lived in the sea. When once this was admitted, the further steps
+were comparatively easy, and at the present day no geological
+doctrine stands on a firmer basis than that which teaches us
+that our present continents and islands, fixed and immovable as
+they appear, have been repeatedly sunk beneath the ocean.
+</p>
+
+<h3>
+<a name="page_57"><span class="page">Page 57</span></a>
+CHAPTER VI.</h3>
+
+<p class="subtitle">
+THE BIOLOGICAL RELATIONS OF FOSSILS.
+</p>
+
+<p class="indent">
+Not only have fossils, as we have seen, a most important bearing
+upon the sciences of Geology and Physical Geography, but they
+have relations of the most complicated and weighty character with
+the numerous problems connected with the study of living beings,
+or in other words, with the science of Biology. To such an extent
+is this the case, that no adequate comprehension of Zoology and
+Botany, in their modern form, is so much as possible without
+some acquaintance with the types of animals and plants which have
+passed away. There are also numerous speculative questions in
+the domain of vital science, which, if soluble at all, can only
+hope to find their key in researches carried out on extinct
+organisms. To discuss fully the biological relations of fossils
+would, therefore, afford matter for a separate treatise; and all
+that can be done here is to indicate very cursorily the principal
+points to which the attention of the palæontological student
+ought to be directed.
+</p>
+
+<p class="indent">
+In the first place, the great majority of fossil animals and
+plants are "extinct"&mdash;that is to say, they belong to species
+which are no longer in existence at the present day. So far,
+however, from there being any truth in the old view that there
+were periodic destructions of all the living beings in existence
+upon the earth, followed by a corresponding number of new creations
+of animals and plants, the actual facts of the case show that
+the extinction of old forms and the introduction of new forms
+have been processes constantly going on throughout the whole
+of geological time. Every species seems to come into being at
+a certain definite point of time, and to finally disappear at
+another definite point; though there are few instances indeed,
+if there are any, in which our present knowledge would permit
+us safely to fix with precision the times of entrance and exit.
+There are, moreover, marked differences in the actual time during
+which different species remained in existence, and therefore
+corresponding differences in their "vertical range," or, in other
+words, in the actual amount and thickness of strata through which
+they present themselves as fossils. Some species are found to
+range through two or even three formations, and a few have an even
+more extended life. More commonly the species which begin in the
+<a name="page_58"><span class="page">Page 58</span></a>
+commencement of a great formation die
+out at or before its close, whilst those which are introduced for
+the first time near the middle or end of the formation may either
+become extinct, or may pass on into the next succeeding formation.
+As a general rule, it is the animals which have the lowest and
+simplest organisation that have the longest range in time, and
+the additional possession of microscopic or minute dimensions
+seems also to favour longevity. Thus some of the <i>Foraminifera</i>
+appear to have survived, with little or no perceptible alteration,
+from the Silurian period to the present day; whereas large and
+highly-organised animals, though long-lived as <i>individuals</i>,
+rarely seem to live long <i>specifically</i>, and have, therefore,
+usually a restricted vertical range. Exceptions to this, however,
+are occasionally to be found in some "persistent types," which
+extend through a succession of geological periods with very
+little modification. Thus the existing Lampshells of the genus
+<i>Lingula</i> are little changed from the <i>Lingulœ</i>
+which swarmed in the Lower Silurian seas; and the existing Pearly
+Nautilus is the last descendant of a clan nearly as ancient. On
+the other hand, some forms are singularly restricted in their
+limits, and seem to have enjoyed a comparatively brief lease
+of life. An example of this is to be found in many of the
+<i>Ammonites</i>&mdash;close allies of the Nautilus&mdash;which
+are often confined strictly to certain zones of strata, in some
+cases of very insignificant thickness.
+</p>
+
+<p class="indent">
+Of the <i>causes</i> of extinction amongst fossil animals and
+plants, we know little or nothing. All we can say is, that the
+attributes which constitute a <i>species</i> do not seem to be
+intrinsically endowed with permanence, any more than the attributes
+which constitute an <i>individual</i>, though the former may
+endure whilst many successive generations of the latter have
+disappeared. Each species appears to have its own life-period,
+its commencement, its culmination, and its gradual decay; and
+the life-periods of different species may be of very different
+duration.
+</p>
+
+<p class="indent">
+From what has been said above, it may be gathered that our existing
+species of animals and plants are, for the most part, quite of modern
+origin, using the term "modern" in its geological acceptation.
+Measured by human standards, the majority of existing animals
+(which are capable of being preserved as fossils) are known to
+have a high antiquity; and some of them can boast of a pedigree
+which even the geologist may regard with respect. Not a few of
+our shellfish are known to have commenced their existence at some
+point of the Tertiary period; one Lampshell
+<a name="page_59"><span class="page">Page 59</span></a>
+(<i>Terebratulina caput-serpentis</i>) is believed to have
+survived since the Chalk; and some of the <i>Foraminifera</i> date,
+at any rate, from the Carboniferous period. We learn from this
+the additional fact that our existing animals and plants do not
+constitute an assemblage of organic forms which were introduced
+into the world collectively and simultaneously, but that they
+commenced their existence at very different periods, some being
+extremely old, whilst others may be regarded as comparatively
+recent animals. And this introduction of the existing fauna and
+flora was a slow and <i>gradual</i> process, as shown admirably
+by the study of the fossil shells of the Tertiary period. Thus,
+in the earlier Tertiary period, we find about 95 per cent of the
+known fossil shells to be species that are no longer in existence,
+the remaining 5 per cent being forms which are known to live in
+our present seas. In the middle of the Tertiary period we find
+many more recent and still existing species of shells, and the
+extinct types are much fewer in number; and this gradual
+introduction of forms now living goes on steadily, till, at the
+close of the Tertiary period, the proportions with which we
+started may be reversed, as many as 90 or 95 per cent of the
+fossil shells being forms still alive, while not more than 5
+per cent may have disappeared.
+</p>
+
+<p class="indent">
+All known animals at the present day may be divided into some
+five or six primary divisions, which are known technically as
+"<i>sub-kingdoms</i>." Each of these sub-kingdoms [9] may be
+regarded as representing a certain type or plan of structure,
+and all the animals comprised in each are merely modified forms
+of this common type. Not only are all known living animals thus
+reducible to some five or six fundamental plans of structure,
+but amongst the vast series of fossil forms no one has yet been
+found&mdash;however unlike any existing animal&mdash;to possess
+peculiarities which would entitle it to be placed in a new
+sub-kingdom. All fossil animals, therefore, are capable of
+being referred to one or other of the primary divisions of the
+animal kingdom. Many fossil groups have no closely-related group
+now in existence; but in no case do we meet with any grand
+structural type which has not survived to the present day.
+</p>
+
+<p class="footnote">
+[Footnote 9: In the Appendix a brief definition is given of the
+sub-kingdoms, and the chief divisions of each are enumerated.]
+</p>
+
+<p class="indent">
+The old types of life differ in many respects from those now
+upon the earth; and the further back we pass in time, the more
+marked does this divergence become. Thus, if we were to compare
+the animals which lived in the Silurian seas with
+<a name="page_60"><span class="page">Page 60</span></a>
+those inhabiting our present oceans, we should in most
+instances find differences so great as almost to place us in
+another world. This divergence is the most marked in the
+Palæozoic forms of life, less so in those of the Mesozoic
+period, and less still in the Tertiary period. Each successive
+formation has therefore presented us with animals becoming
+gradually more and more like those now in existence; and though
+there is an immense and striking difference between the Silurian
+animals and those of to-day, this difference is greatly reduced
+if we compare the Silurian fauna with the Devonian; <i>that</i>
+again with the Carboniferous; and so on till we reach the present.
+</p>
+
+<p class="indent">
+It follows from the above that the animals of any given formation
+are more like those of the next formation below, and of the next
+formation above, than they are to any others; and this fact of
+itself is an almost inexplicable one, unless we believe that
+the animals of any given formation are, in part at any rate, the
+lineal descendants of the animals of the preceding formation,
+and the progenitors, also in part at least, of the animals of the
+succeeding formation. In fact, the palæontologist is so
+commonly confronted with the phenomenon of closely-allied forms of
+animal life succeeding one another in point of time, that he is
+compelled to believe that such forms have been developed from
+some common ancestral type by some process of "<i>evolution</i>."
+On the other hand, there are many phenomena, such as the apparently
+sudden introduction of new forms throughout all past time, and
+the common occurrence of wholly isolated types, which cannot
+be explained in this way. Whilst it seems certain, therefore,
+that many of the phenomena of the succession of animal life in
+past periods can only be explained by some law of evolution, it
+seems at the same time certain that there has always been some
+other deeper and higher law at work, on the nature of which it
+would be futile to speculate at present.
+</p>
+
+<p class="indent">
+Not only do we find that the animals of each successive formation
+become gradually more and more like those now existing upon the
+globe, as we pass from the older rocks into the newer, but we also
+find that there has been a gradual progression and development in
+the <i>types</i> of animal life which characterise the geological
+ages. If we take the earliest-known and oldest examples of any
+given group of animals, it can sometimes be shown that these
+primitive forms, though in themselves highly organised, possessed
+certain characters such as are now only seen in the <i>young</i>
+of their existing representatives. In technical language, the
+early forms of life in some
+<a name="page_61"><span class="page">Page 61</span></a>
+instances possess
+"<i>embryonic</i>" characters, though this does not prevent them
+often attaining a size much more gigantic than their nearest living
+relatives. Moreover, the ancient forms of life are often what is
+called "comprehensive types"&mdash;that is to say, they possess
+characters in combination such as we nowadays only find separately
+developed in different, groups of animals. Now, this permanent
+retention of embryonic characters and this "comprehensiveness" of
+structural type are signs of what a zoologist considers to be a
+comparatively low grade of organisation; and the prevalence of
+these features in the earlier forms of animals is a very striking
+phenomenon, though they are none the less perfectly organised so
+far as their own type is concerned. As we pass upwards in the
+geological scale, we find that these features gradually disappear,
+higher and ever higher forms are introduced, and "specialisation"
+of type takes the place of the former comprehensiveness. We shall
+have occasion to notice many of the facts on which these views are
+based at a later period, and in connection with actual examples.
+In the meanwhile, it is sufficient to state, as a widely-accepted
+generalisation of palæontology, that there has been in the past
+a general progression of organic types, and that the appearance
+of the lower forms of life has in the main preceded that of the
+higher forms in point of time.
+</p>
+
+<h2><a name="page_63"><span class="page">Page 63</span>
+PART II.</a></h2>
+
+<hr />
+
+<p class="part">
+HISTORICAL PALÆONTOLOGY.
+</p>
+
+<h3>
+<a name="page_65"><span class="page">Page 65</span></a>
+CHAPTER VII.</h3>
+
+<p class="subtitle">
+THE LAURENTIAN AND HURONIAN PERIODS.
+</p>
+
+<p class="indent">
+The <i>Laurentian Rocks</i> constitute the base of the entire
+stratified series, and are, therefore, the oldest sediments of
+which we have as yet any knowledge. They are more largely and more
+typically developed in North America, and especially in Canada,
+than in any known part of the world, and they derive their title
+from the range of hills which the old French geographers named
+the "Laurentides." These hills are composed of Laurentian Rocks,
+and form the watershed between the valley of the St Lawrence river
+on the one hand, and the great plains which stretch northwards
+to Hudson Bay on the other hand. The main area of these ancient
+deposits forms a great belt of rugged and undulating country,
+which extends from Labrador westwards to Lake Superior, and then
+bends northwards towards the Arctic Sea. Throughout this extensive
+area the Laurentian Rocks for the most part present themselves
+in the form of low, rounded, ice-worn hills, which, if generally
+wanting in actual sublimity, have a certain geological grandeur
+from the fact that they "have endured the battles and the storms
+of time longer than any other mountains" (Dawson). In some places,
+however, the Laurentian Rocks produce scenery of the most magnificent
+character, as in the great gorge cut through them by the river
+Saguenay, where they rise at times into vertical precipices 1500
+feet in height. In the famous group of the Adirondack mountains,
+also, in the state of New York, they form elevations no less than
+6000 feet above the level of the sea. As a general rule, the
+character of the Laurentian region is that of a rugged, rocky,
+rolling country, often
+<a name="page_66"><span class="page">Page 66</span></a>
+densely timbered, but rarely well fitted for agriculture, and
+chiefly attractive to the hunter and the miner.
+</p>
+
+<p class="indent">
+As regards its mineral characters, the Laurentian series is composed
+throughout of metamorphic and highly crystalline rocks, which are
+in a high degree crumpled, folded, and faulted. By the late Sir
+William Logan the entire series was divided into two great groups,
+the <i>Lower Laurentian</i> and the <i>Upper Laurentian</i>, of
+which the latter rests unconformably upon the truncated edges
+of the former, and is in turn unconformably overlaid by strata
+of Huronian and Cambrian age (fig. 20).
+</p>
+
+<p class="indent">
+The <i>Lower Laurentian</i> series attains the enormous thickness
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 597px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig020.jpg" width="589" height="79" alt="Fig. 20" />
+<br />
+Fig. 20.&mdash;Diagrammatic section of the Laurentian
+Rocks in Lower Canada. <i>a</i> Lower Laurentian; <i>b</i> Upper
+Laurentian, resting unconformably upon the lower series; <i>c</i>
+Cambrian strata (Potsdam Sandstone), resting unconformably on
+the Upper Laurentian.
+</span>
+</span>
+
+of over 20,000 feet, and is composed mainly of great beds of gneiss,
+altered sandstones (quartzites), mica-schist, hornblende-schist,
+magnetic iron-ore, and hæmatite, together with masses of
+limestone. The limestones are especially interesting, and have an
+extraordinary development&mdash;three principal beds being known, of
+which one is not less than 1500 feet thick; the collective
+thickness of the whole being about 3500 feet.
+</p>
+
+<p class="indent">
+The <i>Upper Laurentian</i> series, as before said, reposes
+unconformably upon the Lower Laurentian, and attains a thickness of
+at least 10,000 feet. Like the preceding, it is wholly metamorphic,
+and is composed partly of masses of gneiss and quartzite; but it
+is especially distinguished by the possession of great beds of
+felspathic rock, consisting principally of "Labrador felspar."
+</p>
+
+<p class="indent">
+Though typically developed in the great Canadian area already
+spoken of, the Laurentian Rocks occur in other localities, both
+in America and in the Old World. In Britain, the so-called
+"fundamental gneiss" of the Hebrides and of Sutherlandshire is
+probably of Lower Laurentian age, and the "hypersthene rocks"
+of the Isle of Skye may, with great probability, be regarded
+as referable to the Upper Laurentian. In other localities in
+Great Britain (as in St David's, South Wales; the Malvern Hills;
+and the North of Ireland) occur ancient metamorphic deposits
+which also are probably referable to the Laurentian series. The
+so-called "primitive gneiss" of Norway appears to belong to the
+Laurentian, and the
+<a name="page_67"><span class="page">Page 67</span></a>
+ancient metamorphic rocks of Bohemia and Bavaria may be regarded
+as being approximately of the same age.
+</p>
+
+<p class="indent">
+By some geological writers the ancient and highly metamorphosed
+sediments of the Laurentian and the succeeding Huronian series
+have been spoken of as the "Azoic rocks" (Gr. <i>a</i>, without;
+<i>zoe</i>, life); but even if we were wholly destitute of any
+evidence of life during these periods, this name would be
+objectionable upon theoretical grounds. If a general name be
+needed, that of "Eozoic" (Gr. <i>eos</i>, dawn; <i>zoe</i>, life),
+proposed by Principal Dawson, is the most appropriate. Owing
+to their metamorphic condition, geologists long despaired of
+ever detecting any traces of life in the vast pile of strata
+which constitute the Laurentian System. Even before any direct
+traces were discovered, it was, however, pointed out that there
+were good reasons for believing that the Laurentian seas had been
+tenanted by an abundance of living beings. These reasons are
+briefly as follows:&mdash;(1) Firstly, the Laurentian series consists,
+beyond question, of marine sediments which originally differed
+in no essential respect from those which were subsequently laid
+down in the Cambrian or Silurian periods. (2) In all formations
+later than the Laurentian, any limestones which are present can
+be shown, with few exceptions, to be <i>organic</i> rocks, and to
+be more or less largely made up of the comminuted debris of marine
+or fresh-water animals. The Laurentian limestones, in consequence
+of the metamorphism to which they have been subjected, are so
+highly crystalline (fig. 21) that the microscope fails to detect
+
+<span style="float: right; margin: 4px; width: 263px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig021.jpg" width="255" height="255" alt="Fig. 21" />
+<br />
+Fig. 21.&mdash;Section of Lower Laurentian Limestone from Hull,
+Ottawa; enlarged five diameters. The rock is very highly
+crystalline, and contains mica and other minerals. The irregular
+black masses in it are graphite. (Original.)
+</span>
+
+any organic structure in the rock, and no fossils beyond those
+which will be spoken of immediately have as yet been discovered in
+them. We know, however, of numerous cases in which limestones,
+of later age, and undoubtedly organic to begin with, have been
+rendered so intensely crystalline by metamorphic action that
+all traces of organic structure have been obliterated. We have
+therefore, by analogy, the strongest possible ground for believing
+that the vast beds of Laurentian limestone have been originally
+organic in their origin, and primitively composed, in the main,
+of the calcareous skeletons
+<a name="page_68"><span class="page">Page 68</span></a>
+of marine
+animals. It would, in fact, be a matter of great difficulty to
+account for the formation of these great calcareous masses on any
+other hypothesis. (3) The occurrence of phosphate of lime in the
+Laurentian Rocks in great abundance, and sometimes in the form of
+irregular beds, may very possibly be connected with the former
+existence in the strata of the remains of marine animals of whose
+skeleton this mineral is a constituent. (4) The Laurentian Rocks
+contain a vast amount of carbon in the form of black-lead or
+<i>graphite</i>. This mineral is especially abundant in the
+limestones, occurring in regular beds, in veins or strings, or
+disseminated through the body of the limestone in the shape of
+crystals, scales, or irregular masses. The amount of graphite in
+some parts of the Lower Laurentian is so great that it has been
+calculated as equal to the quantity of carbon present in an equal
+thickness of the Coal-measures. The general source of solid
+carbon in the crust of the earth is, however, plant-life; and it
+seems impossible to account for the Laurentian graphite, except
+upon the supposition that it is metamorphosed vegetable matter.
+(5) Lastly, the great beds of iron-ore (peroxide and magnetic
+oxide) which occur in the Laurentian series interstratified with
+the other rocks, point with great probability to the action of
+vegetable life; since similar deposits in later formations can
+commonly be shown to have been formed by the deoxidising power
+of vegetable matter in a state of decay.
+</p>
+
+<p class="indent">
+In the words of Principal Dawson, "anyone of these reasons might,
+in itself, be held insufficient to prove so great and, at first
+sight, unlikely a conclusion as that of the existence of abundant
+animal and vegetable life in the Laurentian; but the concurrence
+of the whole in a series of deposits unquestionably marine, forms
+a chain of evidence so powerful that it might command belief
+even if no fragment of any organic or living form or structure
+had ever been recognised in these ancient rocks." Of late years,
+however, there have been discovered in the Laurentian Rocks certain
+bodies which are believed to be truly the remains of animals, and
+of which by far the most important is the structure known under
+the now celebrated name of <i>Eozoön</i>. If truly organic,
+a very special and exceptional interest attaches itself to
+<i>Eozoön</i>, as being the most ancient fossil animal of which
+we have any knowledge; but there are some who regard it really
+a peculiar form of mineral structure, and a severe, protracted,
+and still unfinished controversy has been carried on as to its
+nature. Into this controversy it is wholly unnecessary to enter
+here; and it will be sufficient to briefly explain the structure
+of <i>Eozoön</i>, as elucidated by the elaborate and masterly
+investigations of Carpenter
+<a name="page_69"><span class="page">Page 69</span></a>
+and Dawson, from the standpoint that it is a genuine
+organism&mdash;the balance of evidence up to this moment inclining
+decisively to this view.
+</p>
+
+<p class="indent">
+The structure known as <i>Eozoön</i> is found in various
+localities in the Lower Laurentian limestones of Canada, in the form
+of isolated masses or spreading layers, which are composed of thin
+alternating laminæ, arranged more or less concentrically (fig.
+22). The laminæ of these masses are usually of different colours
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 488px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig022.jpg" width="480" height="255" alt="Fig. 22" />
+<br />
+Fig. 22.&mdash;Fragment of <i>Eozoön</i>, of the natural size,
+showing alternate laminæ of loganite and dolomite. (After
+Dawson.)
+</span>
+</span>
+
+and composition; one series being white, and composed of carbonate
+of lime&mdash;whilst the laminæ of the second series alternate
+with the preceding, are green in colour, and are found by chemical
+analysis to consist of some silicate, generally serpentine or the
+closely-related "loganite." In some instances, however, all the
+laminæ are calcareous, the concentric arrangement still remaining
+visible in consequence of the fact that the laminæ are composed
+alternately of lighter and darker coloured limestone.
+</p>
+
+<p class="indent">
+When first discovered, the masses of <i>Eozoön</i> were supposed
+to be of a mineral nature; but their striking general resemblance
+to the undoubted fossils which will be subsequently spoken of under
+the name of <i>Stromatopora</i> was recognised by Sir William
+Logan, and specimens were submitted for minute examination, first
+to Principal Dawson, and subsequently to Dr W. B. Carpenter.
+After a careful microscopic examination, these two distinguished
+observers came to the conclusion that <i>Eozoön</i> was truly
+organic, and in this opinion they were afterwards corroborated
+by other high authorities (Mr W. K. Parker, Professor Rupert
+Jones, Mr H. B. Brady, Professor G&uuml;mbel, &amp;c.) Stated briefly,
+the structure of <i>Eozoön</i>, as exhibited by the microscope,
+is as follows:&mdash;
+</p>
+
+<p class="indent">
+<a name="page_70"><span class="page">Page 70</span></a>
+The concentrically-laminated mass of <i>Eozoön</i> is composed
+of numerous calcareous layers, representing the original skeleton
+of the organism (fig. 23, <i>b</i>). These calcareous layers
+
+<span style="float: left; margin: 4px; width: 342px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig023.jpg" width="334" height="273" alt="Fig. 23" />
+<br />
+Fig. 23.&mdash;Diagram of a portion of <i>Eozoön</i>
+cut vertically. A, B, C, Three tiers of chambers communicating
+with one another by slightly constricted apertures: <i>a a</i>,
+The true shell-wall, perforated by numerous delicate tubes; <i>b
+b</i>. The main calcareous skeleton ("intermediate skeleton");
+<i>c</i>, Passage of communication ("stolon-passage") from one
+tier of chambers to another; <i>d</i>, Ramifying tubes in the
+calcareous skeleton. (After Carpenter.)
+</span>
+
+serve to separate and define a series of chambers arranged in
+successive tiers, one above the other (fig. 23, A, B, C); and
+they are perforated not only by passages (fig. 23, <i>c</i>),
+which serve to place successive tiers of chambers in communication,
+but also by a system of delicate branching canals (fig. 23,
+<i>d</i>). Moreover, the central and principal portion of each
+calcareous layer, with the ramified canal-system just spoken
+of, is bounded both above and below by a thin lamina which has
+a structure of its own, and which may be regarded as the proper
+shell-wall (fig. 23, <i>a a</i>). This proper wall forms the
+actual lining of the chambers, as well as the outer surface of
+the whole mass; and it is perforated with numerous fine vertical
+tubes (fig. 24, <i>a a</i>), opening into the chambers and on to
+the surface by corresponding fine pores. From the resemblance
+of this tubulated layer to similar structures in the shell of
+the Nummulite, it is often spoken of as the "Nummuline layer."
+The chambers are sometimes piled up one above the other in an
+irregular manner; but they are more commonly arranged in regular
+tiers, the separate chambers being marked off from one another
+by projections of the wall in the form of partitions, which are
+so far imperfect as to allow of a free communication between
+contiguous chambers. In the original condition of the organism,
+all these chambers, of course, must have been filled with
+living-matter; but they are found in the present state of the
+fossil to be generally filled with some silicate, such as serpentine,
+which not only fills the actual chambers, but has also penetrated
+the minute tubes of the proper wall and the branching canals of
+the intermediate skeleton. In some cases
+<a name="page_71"><span class="page">Page 71</span></a>
+the chambers are simply filled with crystalline carbonate of lime.
+When the originally porous fossil has been permeated by a silicate,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 396px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig024.jpg" width="388" height="355" alt="Fig. 24" />
+<br />
+Fig. 24.&mdash;The animal of <i>Nonionina</i>, one of the
+<i>Foraminifera</i>, after the shell has been removed by
+a weak acid; <i>b, Gromia</i>, a single-chambered Foraminifer
+(after Schultze), showing the shell surrounded by a network of
+filaments derived from the body substance.
+</span>
+</span>
+
+it is possible to dissolve away the whole of the calcareous skeleton
+by means of acids, leaving an accurate and beautiful cast of the
+chambers and the tubes connected with them in the insoluble silicate.
+</p>
+
+<p class="indent">
+The above are the actual appearances presented by <i>Eozoön</i>
+when examined microscopically, and it remains to see how far they
+enable us to decide upon its true position in the animal kingdom.
+Those who wish to study this interesting subject in detail must
+consult the admirable memoirs by Dr W. B. Carpenter and Principal
+Dawson: it will be enough here to indicate the results which
+have been arrived at. The only animals at the present day which
+possess a continuous calcareous skeleton, perforated by pores and
+penetrated by canals, are certain organisms belonging to the
+group of the <i>Foraminifera</i>. We have had occasion before
+to speak of these animals, and as they are not conspicuous or
+commonly-known forms of life, it may be well to say a few words as
+to the structure of the living representatives of the group. The
+<i>Foraminifera</i> are all inhabitants of the sea, and are mostly
+of small or even microscopic dimensions. Their bodies are composed
+<a name="page_72"><span class="page">Page 72</span></a>
+of an apparently structureless animal
+substance of an albuminous nature ("sarcode"), of a gelatinous
+consistence, transparent, and exhibiting numerous minute granules
+or rounded particles. The body-substance cannot be said in itself
+to possess any definite form, except in so far as it may be bounded
+by a shell; but it has the power, wherever it may be exposed, of
+emitting long thread-like filaments ("pseudopodia"), which interlace
+with one another to form a network (fig. 25, <i>b</i>). These
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 370px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig025.jpg" width="362" height="557" alt="Fig. 25" />
+<br />
+Fig. 25.&mdash;The animal of <i>Nonionina</i>, one of the
+<i>Foraminifera</i>, after the shell has been removed by
+a weak acid; <i>b, Gromia</i>, a single-chambered Foraminifer
+(after Schultze), showing the shell surrounded by a network of
+filaments derived from the body substance.
+</span>
+</span>
+
+filaments can be thrown out at will, and to considerable distances,
+and can be again retracted into the soft mass of the general
+body-substance, and they are the agents by which the animal obtains
+its food. The soft bodies of the <i>Foraminifera</i> are protected
+by a shell, which is usually calcareous, but may be composed of
+sand-grains cemented
+<a name="page_73"><span class="page">Page 73</span></a>
+together; and it may consist
+of a single chamber (fig. 26, <i>a</i>), or of many chambers arranged
+in different ways (fig. 26, <i>b-f</i>). Sometimes the shell has but
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 564px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig026.jpg" width="556" height="485" alt="Fig. 26" />
+<br />
+Fig. 26.&mdash;Shells of living <i>Foraminifera</i>.
+<i>a, Orbulina universa</i>, in its perfect condition, showing
+the tubular spines which radiate from the surface of the shell;
+<i>b, Globigerina bulloides</i>, in its ordinary condition, the
+thin hollow spines which are attached to the shell when perfect
+having been broken off; <i>c, Textularia variabilis; d, Peneroplis
+planatus; e, Rotalia concamerata; f, Cristellaria subarcuatula.</i>
+[Fig. <i>a</i> is after Wyville Thomson; the others are after
+Williamson. All the figures are greatly enlarged.
+</span>
+</span>
+
+one large opening into it&mdash;the mouth; and then it is from this
+aperture that the animal protrudes the delicate net of filaments
+with which it seeks its food. In other cases the entire shell
+is perforated with minute pores (fig. 26, <i>e</i>), through
+which the soft body-substance gains the exterior, covering the
+whole shell with a gelatinous film of animal matter, from which
+filaments can be emitted at any point. When the shell consists
+of many chambers, all of these are placed in direct communication
+with one another, and the actual substance of the shell is often
+traversed by minute canals filled with living matter (<i>e.g.</i>,
+in <i>Calcarina</i> and <i>Nummulina</i>). The shell, therefore,
+may be regarded, in such cases, as a more or less completely
+porous calcareous structure,
+<a name="page_74"><span class="page">Page 74</span></a>
+filled to its minutest internal recesses with the substance of the
+living animal, and covered externally with a layer of the same
+substance, giving off a network of interlacing filaments.
+</p>
+
+<p class="indent">
+Such, in brief, is the structure of the living <i>Foraminifera</i>;
+and it is believed that in <i>Eozoön</i> we have an extinct
+example of the same group, not only of special interest from its
+immemorial antiquity, but hardly less striking from its gigantic
+dimensions. In its original condition, the entire chamber-system
+of <i>Eozoön</i> is believed to have been filled with soft
+structureless living matter, which passed from chamber to chamber
+through the wide apertures connecting these cavities, and from
+tier to tier by means of the tubuli in the shell-wall and the
+branching canals in the intermediate skeleton. Through the
+perforated shell-wall covering the outer surface the soft
+body-substance flowed out, forming a gelatinous investment, from
+every point of which radiated an interlacing net of delicate
+filaments, providing nourishment for the entire colony. In its
+present state, as before said, all the cavities originally
+occupied by the body-substance have been filled with some mineral
+substance, generally with one of the silicates of magnesia; and
+it has been asserted that this fact militates strongly against
+the organic nature of <i>Eozoön</i>, if not absolutely
+disproving it. As a matter of fact, however&mdash;as previously
+noticed&mdash;it is by no means very uncommon at the present day
+to find the shells of living species of <i>Foraminifera</i> in
+which all the cavities primitively occupied by the body-substance,
+down to the minutest pores and canals, have been similarly
+injected by some analogous silicate, such as glauconite.
+</p>
+
+<p class="indent">
+Those, then, whose opinions on such a subject deservedly carry the
+greatest weight, are decisively of opinion that we are presented
+in the <i>Eozoön</i> of the Laurentian Rocks of Canada with an
+ancient, colossal, and in some respects abnormal type of the
+<i>Foraminifera</i>. In the words of Dr Carpenter, it is not
+pretended that "the doctrine of the Foraminiferal nature of
+<i>Eozoön</i> can be <i>proved</i> in the demonstrative sense;"
+but it may be affirmed "that the <i>convergence of a number of
+separate and independent probabilities</i>, all accordant with
+that hypothesis, while a separate explanation must be invented
+for each of them on any other hypothesis, gives it that <i>high
+probability</i> on which we rest in the ordinary affairs of life,
+in the verdicts of juries, and in the interpretation of geological
+phenomena generally."
+</p>
+
+<p class="indent">
+It only remains to be added, that whilst <i>Eozoön</i> is by far
+the most important organic body hitherto found in the Laurentian,
+and has been here treated at proportionate length, other
+<a name="page_75"><span class="page">Page 75</span></a>
+traces of life have been detected, which may subsequently prove of
+great interest and importance. Thus, Principal Dawson has recently
+described under the name of <i>Archœosphœrinœ</i>
+certain singular rounded bodies which he has discovered in the
+Laurentian limestones, and which he believes to be casts of the
+shells of <i>Foraminifera</i> possibly somewhat allied to the
+existing <i>Globigerinœ</i>. The same eminent
+palæontologist has also described undoubted worm-burrows
+from rocks probably of Laurentian age. Further and more extended
+researches, we may reasonably hope, will probably bring to light
+other actual remains of organisms in these ancient deposits.
+</p>
+
+<h4>THE HURONIAN PERIOD.</h4>
+
+<p class="indent">
+The so-called <i>Huronian Rocks</i>, like the Laurentian, have
+their typical development in Canada, and derive their name from
+the fact that they occupy an extensive area on the borders of
+Lake Huron. They are wholly metamorphic, and consist principally
+of altered sandstones or quartzites, siliceous, felspathic, or
+talcose slates, conglomerates, and limestones. They are largely
+developed on the north shore of Lake Superior, and give rise
+to a broken and hilly country, very like that occupied by the
+Laurentians, with an abundance of timber, but rarely with sufficient
+soil of good quality for agricultural purposes. They are, however,
+largely intersected by mineral veins, containing silver, gold,
+and other metals, and they will ultimately doubtless yield a rich
+harvest to the miner. The Huronian Rocks have been identified,
+with greater or less certainty, in other parts of North America,
+and also in the Old World.
+</p>
+
+<p class="indent">
+The total thickness of the Huronian Rocks in Canada is estimated
+as being not less than 18,000 feet, but there is considerable
+doubt as to their precise geological position. In their typical
+area they rest unconformably on the edges of strata of <i>Lower</i>
+Laurentian age; but they have never been seen in direct contact
+with the <i>Upper</i> Laurentian, and their exact relations to
+this series are therefore doubtful. It is thus open to question
+whether the Huronian Rocks constitute a distinct formation, to
+be intercalated in point of time between the Laurentian and the
+Cambrian groups; or whether, rather, they should not be considered
+as the metamorphosed representatives of the Lower Cambrian Rocks
+of other regions.
+</p>
+
+<p class="indent">
+As regards the fossils of the Huronian Rocks, little can be said.
+Some of the specimens of <i>Eozoön Canadense</i> which have
+<a name="page_76"><span class="page">Page 76</span></a>
+been discovered in Canada are thought to come
+from rocks which are probably of Huronian age. In Bavaria,
+Dr G&uuml;mbel has described a species of <i>Eozoön</i> under
+the name of <i>Eozoön Bavaricum</i>, from certain metamorphic
+limestones which he refers to the Huronian formation. Lastly, the
+late Mr Billings described, from rocks in Newfoundland apparently
+referable to the Huronian, certain problematical limpet-shaped
+fossils, to which he gave the name of <i>Aspidella</i>.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+Amongst the works and memoirs which the student may consult with
+regard to the Laurentian and Huronian deposits may be mentioned
+the following:[10]&mdash;
+</p>
+
+<table summary="" style="">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Report of Progress of the Geological Survey of Canada
+  from its Commencement to 1863,' pp. 38-49, and pp. 50-66.</td>
+</tr><tr><td class="right" valign="top">(2)</td>
+ <td>'Manual of Geology.' Dana. 2d Ed. 1875.</td>
+</tr><tr><td class="right" valign="top">(3)</td>
+ <td>'The Dawn of Life.' J. W, Dawson. 1876.</td>
+</tr><tr><td class="right" valign="top">(4)</td>
+ <td>"On the Occurrence of Organic Remains in the Laurentian
+  Rocks of Canada." Sir W. E. Logan. 'Quart. Journ. Geol.'
+  Soc.,' xxi. 45-50.'</td>
+</tr><tr><td class="right" valign="top">(5)</td>
+ <td>"On the Structure of Certain Organic Remains in the
+  Laurentian Limestones of Canada." J. W. Dawson. 'Quart.
+  Journ. Geol. Soc.,' xxi. 51-59.</td>
+</tr><tr><td class="right" valign="top">(6)</td>
+ <td>"Additional Note on the Structure and Affinities of
+  Eozoön Canadense." W. B, Carpenter. 'Quart. Journ.
+  Geol. Soc.,' xxi. 59-66.</td>
+</tr><tr><td class="right" valign="top">(7)</td>
+ <td>"Supplemental Notes on the Structure and Affinities of
+  Eozoön' Canadense," W. B. Carpenter, 'Quart. Journ.
+  Geol. Soc.,' xxii. 219-228.</td>
+</tr><tr><td class="right" valign="top">(8)</td>
+ <td>"On the So-Called Eozoönal Rocks." King &amp; Rowney.
+  'Quart. Journ. Geol. Soc.,' xxii. 185-218.</td>
+</tr><tr><td class="right" valign="top">(9)</td>
+ <td>'Chemical and Geological Essays.' Sterry Hunt.</td>
+</tr>
+</table>
+
+<p class="indent">
+The above list only includes some of the more important memoirs
+which may be consulted as to the geological and chemical features
+of the Laurentian and Huronian Rocks, and as to the true nature
+of <i>Eozoön</i>. Those who are desirous of studying the later
+phases of the controversy with regard to <i>Eozoön</i> must consult
+the papers of Carpenter, Carter, Dawson, King &amp; Rowney, Hahn,
+and others, in the 'Quart. Journ. of the Geological Society,'
+the 'Proceedings of the Royal Irish Academy,' the 'Annals of
+Natural History,' the 'Geological Magazine,' &amp;c. Dr Carpenter's
+'Introduction to the Study of the Foraminifera' should also be
+consulted.
+</p>
+
+<p class="footnote">
+[Footnote 10: In this and in all subsequently following
+bibliographical lists, not only is the selection of works and
+memoirs quoted necessarily extremely limited; but only such have,
+as a general rule, been chosen for mention as are easily accessible
+to students who are in the position of being able to refer to a good
+library. Exceptions, however, are occasionally made to this rule,
+in favour of memoirs or works of special historical interest. It
+is also unnecessary to add that it has not been thought requisite
+to insert in these lists the well-known handbooks of geological
+and palæontological science; except in such instances as where
+they contain special information on special points.]
+</p>
+
+<h3>
+<a name="page_77"><span class="page">Page 77</span></a>
+CHAPTER VIII.</h3>
+
+<p class="subtitle">
+THE CAMBRIAN PERIOD.
+</p>
+
+<p class="indent">
+The traces of life in the Laurentian period, as we have seen, are
+but scanty; but the <i>Cambrian Rocks</i>&mdash;so called from their
+occurrence in North Wales and its borders ("Cambria ")&mdash;have
+yielded numerous remains of animals and some dubious plants. The
+Cambrian deposits have thus a special interest as being the oldest
+rocks in which occur any number of well-preserved and unquestionable
+organisms. We have here the remains of the first <i>fauna</i>, or
+assemblage of animals, of which we have at present knowledge.
+As regards their geographical distribution, the Cambrian Rocks
+have been recognised in many parts of the world, but there is
+some question as to the precise limits of the formation, and
+we may consider that their most typical area is in South Wales,
+where they have been carefully worked out, chiefly by Dr Henry
+Hicks. In this region, in the neighbourhood of the promontory
+of St David's, the Cambrian Rocks are largely developed, resting
+upon an ancient ridge of Pre-Cambrian (Laurentian?) strata, and
+overlaid by the lowest beds of the Lower Silurian. The subjoined
+sketch-section (fig. 27) exhibits in a general manner the succession
+of strata in this locality.
+</p>
+
+<p class="indent">
+From this section it will be seen that the Cambrian Rocks in Wales
+are divided in the first place into a lower and an upper group.
+The <i>Lower Cambrian</i> is constituted at the base by a great
+series of grits, sandstones, conglomerates, and slates, which
+are known as the "Longmynd group," from their vast development in
+the Longmynd Hills in Shropshire, and which attain in North Wales
+a thickness of 8000 feet or more. The Longmynd beds are succeeded
+by the so-called "Menevian group," a series of sandstones, flags,
+and grits, about 600 feet in thickness, and containing a
+considerable number of fossils. The <i>Upper Cambrian</i> series
+consists in its lower portion of nearly 5000 feet of strata,
+principally shaly and slaty, which are known as the "Lingula
+Flags," from the great abundance in them of a shell referable
+to the genus <i>Lingula</i>. These are followed by 1000 feet
+of dark shales and flaggy sandstones, which are known as the
+"Tremadoc slates," from their occurrence near Tremadoc in North
+Wales; and these in turn are surmounted, apparently quite
+conformably, by the basement beds of the Lower Silurian.
+</p>
+
+<p class="indent">
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 551px;
+  font-size: smaller; text-align: center;">
+<a name="page_78"><span class="page">Page 78</span></a>
+GENERALIZED SECTION OF THE CAMBRIAN ROCKS IN WALES
+<br />
+Fig. 27.
+<br />
+<img src="images/fig027.jpg" width="543" height="700" alt="Fig. 27" />
+</span>
+</span>
+The above may be regarded as giving a typical series of the Cambrian
+Rocks in a typical locality; but strata of Cambrian age are known in
+many other regions, of which it is only possible here to allude to
+a few of the most important. In Scandinavia occurs a well-developed
+series of Cambrian deposits, representing both the lower and upper
+parts of the
+<a name="page_79"><span class="page">Page 79</span></a>
+formation. In Bohemia, the
+Upper Cambrian, in particular, is largely developed, and constitutes
+the so-called "Primordial zone" of Barrande. Lastly, in North
+America, whilst the Lower Cambrian is only imperfectly developed,
+or is represented by the Huronian, the Upper Cambrian formation has
+a wide extension, containing fossils similar in character to the
+analogous strata in Europe, and known as the "Potsdam Sandstone."
+The subjoined table shows the chief areas where Cambrian Rocks are
+developed, and their general equivalency:
+</p>
+
+<div class="center">
+<table border="1" cellspacing="0" width="90%">
+
+<tr>
+ <td colspan="4" class="center">TABULAR VIEW OF THE CAMBRIAN
+  FORMATION.</td>
+</tr>
+
+<tr>
+ <td>&nbsp;</td>
+ <td class="center"><i>Britain.</i></td>
+ <td class="center"><i>Europe.</i></td>
+ <td class="center"><i>America.</i></td>
+</tr>
+
+<tr>
+ <td rowspan="2" class="center">Upper Cambrian.</td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>a</i>.</td>
+       <td valign="top" class="left">Tremadoc Slates.</td></tr>
+  </table></td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>a</i>.</td>
+       <td valign="top" class="left">Primordial zone of
+        Bohemia.</td></tr>
+  </table></td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>a</i>.</td>
+       <td valign="top" class="left">Potsdam Sandstone.</td></tr>
+  </table></td>
+</tr>
+
+<tr>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>b</i>.</td>
+       <td valign="top" class="left">Lingula Flags.</td></tr>
+  </table></td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>b</i>.</td>
+       <td valign="top" class="left">Paradoxides Schists,
+        Olenus Schists, and Dictyonema schists of
+        Sweden.</td></tr>
+  </table></td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>b</i>.</td>
+       <td valign="top" class="left">Acadian group of
+        New Brunswick.</td></tr>
+  </table></td>
+</tr>
+
+<tr>
+ <td rowspan="6" class="center">Lower Cambrian.</td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>a</i>.</td>
+       <td valign="top" class="left">Longmynd Beds.</td></tr>
+  </table></td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>a</i>.</td>
+       <td valign="top" class="left">Fucoidal Sandstone of
+        Sweden.</td></tr>
+  </table></td>
+ <td valign="top" class="left">Huronian
+        Formation?</td>
+</tr>
+
+<tr>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>b</i>.</td>
+       <td valign="top" class="left">Llanberis Slates.</td></tr>
+  </table></td>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>b</i>.</td>
+       <td valign="top" class="left"><i>Eophyton</i> Sandstone
+        of Sweden.</td></tr>
+  </table></td>
+ <td>&nbsp;</td>
+</tr>
+
+<tr>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>c</i>.</td>
+       <td valign="top" class="left">Harlech Grits.</td></tr>
+  </table></td>
+ <td>&nbsp;</td>
+ <td>&nbsp;</td>
+</tr>
+
+<tr>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>d</i>.</td>
+       <td valign="top" class="left"><i>Oldhamia</i> Slates
+        of Ireland.</td></tr>
+  </table></td>
+ <td>&nbsp;</td>
+ <td>&nbsp;</td>
+</tr>
+
+<tr>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>e</i>.</td>
+       <td valign="top" class="left">Conglomerates and
+        Sandstones of Sutherlandshire?</td></tr>
+  </table></td>
+ <td>&nbsp;</td>
+ <td>&nbsp;</td>
+</tr>
+
+<tr>
+ <td valign="top" class="left">
+  <table border="0" cellspacing="0" cellpadding="1">
+   <tr><td valign="top" class="left"><i>f</i>.</td>
+       <td valign="top" class="left">Menevian
+         Beds.</td></tr>
+  </table></td>
+ <td>&nbsp;</td>
+ <td>&nbsp;</td>
+</tr>
+
+</table>
+</div>
+
+<p class="indent">
+Like all the older Palæozoic deposits, the Cambrian Rocks,
+though by no means necessarily what would be called actually
+"metamorphic," have been highly cleaved, and otherwise altered
+from their original condition. Owing partly to their indurated
+state, and partly to their great antiquity, they are usually
+found in the heart of mountainous districts, which have undergone
+great disturbance, and have been subjected to an enormous amount
+of denudation. In some cases, as in the Longmynd Hills in
+Shropshire, they form low rounded elevations, largely covered by
+pasture, and with few or no elements of sublimity. In other cases,
+however, they rise into bold and rugged mountains, girded by
+precipitous cliffs. Industrially, the Cambrian Rocks are of
+interest, if only for the reason that the celebrated Welsh slates
+of Llanberis are derived from highly-cleaved beds of this age.
+Taken as a whole, the Cambrian formation is essentially composed
+of arenaceous and
+<a name="page_80"><span class="page">Page 80</span></a>
+muddy sediments, the
+latter being sometimes red, but more commonly nearly black in
+colour. It has often been supposed that the Cambrians are a
+deep-sea deposit, and that we may thus account for the few
+fossils contained in them; but the paucity of fossils is to a
+large extent imaginary, and some of the Lower Cambrian beds
+of the Longmynd Hills would appear to have been laid down in
+shallow water; as they exhibit rain-prints, sun-cracks, and
+ripple-marks&mdash;incontrovertible evidence of their having been
+a shore-deposit. The occurrence, of innumerable worm-tracks and
+burrows in many Cambrian strata is also a proof of shallow-water
+conditions; and the general absence of limestones, coupled with
+the coarse mechanical nature of many of the sediments of the
+Lower Cambrian, maybe taken as pointing in the same direction.
+</p>
+
+<p class="indent">
+The <i>life</i> of the Cambrian, though not so rich as in the
+succeeding Silurian period, nevertheless consists of representatives
+of most of the great classes of invertebrate animals. The coarse
+sandy deposits of the formation, which abound more particularly
+towards its lower part, naturally are to a large extent barren
+of fossils; but the muddy sediments, when not too highly cleaved,
+and especially towards the summit of the group, are replete with
+organic remains. This is also the case, in many localities at any
+rate, with the finer beds of the Potsdam Sandstone in America.
+Limestones are known to occur in only a few areas (chiefly in
+America), and this may account for the apparent total absence
+of corals. It is, however, interesting to note that, with this
+exception, almost all the other leading groups of Invertebrates
+are known to have come into existence during the Cambrian period.
+</p>
+
+<p class="indent">
+Of the land-surfaces of the Cambrian period we know nothing;
+and there is, therefore, nothing surprising in the fact that
+our acquaintance with the Cambrian vegetation is confined to
+some marine plants or sea-weeds, often of a very obscure and
+problematical nature. The "Fucoidal Sandstone" of Sweden, and the
+"Potsdam Sandstone" of North America, have both yielded numerous
+remains which have been regarded as markings left by sea-weeds or
+"Fucoids;" but these are highly enigmatical in their characters,
+and would, in many instances, seem to be rather referable to the
+tracks and burrows of marine worms. The first-mentioned of these
+formations has also yielded the curious, furrowed and striated
+stems which have been described as a kind of land-plant under the
+name of <i>Eopkyton</i> (fig. 28). It cannot be said, however,
+that the vegetable origin of these singular bodies has been
+satisfactorily proved. Lastly, there are found in certain green
+<a name="page_81"><span class="page">Page 81</span></a>
+and purple beds of Lower Cambrian age at Bray Head, Wicklow,
+Ireland, some very remarkable fossils, which are well known under
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 436px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig028.jpg" width="428" height="536" alt="Fig. 28" />
+<br />
+Fig. 28.&mdash;Fragment of <i>Eophyton Linneanum</i>, a supposed
+land-plant. Lower Cambrian, Sweden, of the natural size.
+</span>
+</span>
+
+the name of <i>Oldhamia</i>, but the true nature of which is
+very doubtful. The commonest form of <i>Oldhamia</i> (fig. 29)
+consists of a thread-like stem or axis, from which spring at
+regular intervals bundles of short filamentous branches in a
+fan-like manner. In the locality where it occurs, the fronds
+of <i>Oldhamia</i> are very abundant, and are spread over the
+surfaces of the strata in tangled layers. That it is organic
+is certain, and that it is a calcareous sea-weed is probable;
+but it may possibly belong to the sea-mosses (<i>Polyzoa</i>),
+or to the sea-firs (<i>Sertularians</i>).
+</p>
+
+<p class="indent">
+Amongst the lower forms of animal life (<i>Protozoa</i>), we
+find the Sponges represented by the curious bodies, composed
+of netted fibres, to which the name of <i>Protospongia</i> has
+been given (fig. 32, <i>a</i>); and the comparatively gigantic,
+conical, or
+<a name="page_82"><span class="page">Page 82</span></a>
+cylindrical fossils termed <i>Archœocyathus</i> by Mr
+Billings are certainly referable either to the <i>Foraminifera</i>
+
+<span style="float: left; margin: 4px; width: 243px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig029.jpg" width="235" height="330" alt="Fig. 29" />
+<br />
+Fig. 29.&mdash;A portion of <i>Oldhamia antiqua</i>, Lower
+Cambrian, Wicklow, Ireland, of the natural size. (After Salter.)
+</span>
+
+or to the Sponges. The almost total absence of limestones in
+the formation may be regarded as a sufficient explanation of
+the fact that the <i>Foraminifera</i> are not more largely and
+unequivocally represented; though the existence of greensands
+in the Cambrian beds of Wisconsin and Tennessee may be taken as
+an indication that this class of animals was by no means wholly
+wanting. The same fact may explain the total absence of corals,
+so far as at present known.
+</p>
+
+<p class="indent">
+The group of the <i>Echinodermata</i> (Sea-lilies, Sea-urchins,
+and their allies) is represented by a few forms, which are
+principally of interest as being the earliest-known examples of
+the class. It is also worthy of note that these precursors of a
+group which subsequently attains such geological importance, are
+referable to no less than three distinct <i>orders</i>&mdash;the
+Crinoids or Sea-lilies, represented by a species of
+<i>Dendrocrinus</i>; the Cystideans by <i>Protocystites</i>; and
+the Star-fishes by <i>Palasterina</i> and some other forms. Only
+the last of these groups, however, appears to occur in the Lower
+Cambrian.
+</p>
+
+<p class="indent">
+The Ringed-worms (<i>Annelida</i>), if rightly credited with all
+the remains usually referred to them, appear to have swarmed in
+the Cambrian seas. Being soft-bodied, we do not find the actual
+worms themselves in the fossil condition, but we have, nevertheless,
+abundant traces of their existence. In some cases we find vertical
+burrows of greater or less depth, often expanded towards their
+apertures, in which the worm must have actually lived (fig. 30),
+as various species do at the present day. In these cases, the
+tube must have been rendered more or less permanent by receiving
+a coating of mucus, or perhaps a genuine membranous secretion,
+from the body of the animal; and it may be found quite empty, or
+occupied by a cast of sand or mud. Of this nature are the burrows
+which have been described under the names of <i>Scolithus</i> and
+<i>Scolecoderma</i>, and probably the <i>Histioderma</i> of the
+Lower Cambrian
+<a name="page_83"><span class="page">Page 83</span></a>
+of Ireland. In other cases, as in <i>Arenicolites</i>
+(fig. 32, <i>b</i>), the worm seems to have inhabited a double
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 380px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig030.jpg" width="372" height="306" alt="Fig. 30" />
+<br />
+Fig. 30.&mdash;Annelide-burrows (<i>Scolithus linearus</i>)
+from the Potsdam Sandstone of Canada, of the natural size. (After
+Billings.)
+</span>
+</span>
+
+burrow, shaped like the letter U, and having two openings placed
+close together on the surface of the stratum. Thousands of these
+twin-burrows occur in some of the strata of the Longmynd, and
+it is supposed that the worm used one opening to the burrow as
+an aperture of entrance, and the other as one of exit. In other
+cases, again, we find simply the meandering trails caused by the
+worm dragging its body over the surface of the mud. Markings of
+this kind are commoner in the Silurian Rocks, and it is generally
+more or less doubtful whether they may not have been caused by
+other marine animals, such as shellfish, whilst some of them
+have certainly nothing whatever to do with the worms. Lastly,
+the Cambrian beds often show twining cylindrical bodies, commonly
+more or less matted together, and not confined to the surfaces
+of the strata, but passing through them. These have often been
+regarded as the remains of sea-weeds, but it is more probable
+that they represent casts of the underground burrows of worms
+of similar habits to the common lob-worm (<i>Arenicola</i>) of
+the present day.
+</p>
+
+<p class="indent">
+The <i>Articulate</i> animals are numerously represented in the
+Cambrian deposits, but exclusively by the class of
+<i>Crustaceans</i>. Some of these are little double-shelled
+creatures, resembling our living water-fleas (<i>Ostracoda</i>). A
+few are larger forms, and belong to the same group as the existing
+brine-shrimps and fairy-shrimps (<i>Phyllopoda</i>). One of the
+most characteristic
+<a name="page_84"><span class="page">Page 84</span></a>
+of these is the
+<i>Hymenocaris vermicauda</i> of the Lingula Flags (fig.
+32, <i>d</i>). By far the larger number of the Cambrian
+<i>Crustacea</i> belong, however, to the remarkable and wholly
+extinct group of the <i>Trilobites</i>. These extraordinary
+animals must have literally swarmed in the seas of the later
+portion of this and the whole of the succeeding period; and they
+survived in greatly diminished numbers till the earlier portion
+of the Carboniferous period. They died out, however, wholly before
+the close of the Palæozoic epoch, and we have no Crustaceans
+at the present day which can be considered as their direct
+representatives. They have, however, relationships of a more or
+less intimate character with the existing groups of the Phyllopods,
+the King-crabs (<i>Limulus</i>), and the Isopods ("Slaters,"
+Wood-lice, &amp;c.) Indeed, one member of the last-mentioned
+order, namely, the <i>Serolis</i> of the coasts of Patagonia, has
+been regarded as the nearest living ally of the Trilobites. Be
+this as it may, the Trilobites possessed a skeleton which, though
+capable of undergoing almost endless variations, was wonderfully
+constant in its pattern of structure, and we may briefly describe
+here the chief features of this.
+</p>
+
+<p class="indent">
+The upper surface of the body of a Trilobite was defended by a
+strong shell or "crust," partly horny and partly calcareous in
+its composition. This shell (fig. 31) generally exhibits a very
+distinct "trilobation" or division into three longitudinal lobes,
+one central and two lateral. It also exhibits a more important and
+more fundamental division into three transverse portions, which
+are so loosely connected with one another as very commonly to be
+found separate. The first and most anterior of these divisions
+is a shield or buckler which covers the head; the second or middle
+portion is composed of movable rings covering the trunk ("thorax
+"); and the third is a shield which covers the tailor "abdomen."
+The head-shield (fig. 31, <i>e</i>) is generally more or less
+semicircular in shape; and its central portion, covering the
+stomach of the animal, is usually strongly elevated, and generally
+marked by lateral furrows. A little on each side of the head are
+placed the eyes, which are generally crescentic in shape, and
+resemble the eyes of insects and many existing Crustaceans in being
+"compound," or made up of numerous simple eyes aggregated together.
+So excellent is the state of preservation of many specimens of
+Trilobites, that the numerous individual lenses of the eyes have
+been uninjured, and as many as four hundred have been counted in
+each eye of some forms. The eyes may be supported upon prominences,
+but they are never carried on movable stalks (as they are in
+the existing lobsters and crabs); and
+<a name="page_85"><span class="page">Page 85</span></a>
+in some of the Cambrian
+Trilobites, such as the little <i>Agnosti</i> (fig. 31 <i>g</i>),
+the animal was blind. The lateral portions of the head-shield
+are usually separated from the central portion by a peculiar
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig031.jpg" width="569" height="444" alt="Fig. 31" />
+<br />
+Fig. 31.&mdash;Cambrian Trilobites: <i>a, Paradoxides
+Bohemicus</i>, reduced in size; <i>b, Ellipsocephalus Hoffi; c,
+Sao hirsuta; d, Conocorypke Sultzeri</i> (all the above, together
+with fig. <i>g</i>, are from the Upper Cambrian or "Primordial
+Zone" of Bohemia); <i>e</i>, Head-shield of <i>Dikellocephalus
+Celticus</i>, from the Lingula Flags of Wales; <i>f</i>, Head-shield
+of <i>Conocoryphe Matthewi</i>, from the Upper Cambrian (Acadian
+Group) of New Brunswick; <i>g, Agnostus rex</i>, Bohemia; <i>h</i>,
+Tail-shield of <i>Dikellocephalus Minnesotensis</i>, from the
+Upper Cambrian (Potsdam Sandstone) of Minnesota. (After Barrande,
+Dawson, Salter, and Dale Owen.)
+</span>
+</span>
+
+line of division (the so-called "facial suture") on each side;
+but this is also wanting in some of the Cambrian species. The
+backward angles of the head-shield, also, are often prolonged
+into spines, which sometimes reach a great length. Following
+the head-shield behind, we have a portion of the body which is
+composed of movable segments or "body-rings," and which is
+technically called the "thorax," Ordinarily, this region is
+strongly trilobed, and each ring consists of a central convex
+portion, and of two flatter side-lobes. The number of body-rings
+in the thorax is very variable (from two to twenty-six), but is
+fixed for the adult forms of each group of the Trilobites. The
+young forms have much fewer rings than the full-grown ones; and
+it is curious to find that the Cambrian
+<a name="page_86"><span class="page">Page 86</span></a>
+Trilobites very commonly have either a great many rings (as in
+<i>Paradoxides</i>, fig. 31, <i>a</i>), or else very few (as in
+<i>Agnostus</i>, fig. 31, <i>g</i>). In some instances, the
+body-rings do not seem to have been so constructed as to allow
+of much movement, but in other cases this region of the body is
+so flexible that the animal possessed the power of rolling itself
+up completely, like a hedgehog; and many individuals have been
+permanently preserved as fossils in this defensive condition.
+Finally, the body of the Trilobite was completed by a tail-shield
+(technically termed the "pygidium"), which varies much in size
+and form, and is composed of a greater or less number of rings,
+similar to those which form the thorax, but immovably
+amalgamated with one another (fig. 31, <i>h</i>).
+</p>
+
+<p class="indent">
+The under surface of the body in the Trilobites appears to have
+been more or less entirely destitute of hard structures, with the
+exception of a well-developed upper lip, in the form of a plate
+attached to the inferior side of the head-shield in front. There
+is no reason to doubt that the animal possessed legs; but these
+structures seem to have resembled those of many living Crustaceans
+in being quite soft and membranous. This, at any rate, seems to
+have been generally the case; though structures which have been
+regarded as legs have been detected on the under surface of one
+of the larger species of Trilobites. There is also, at present,
+no direct evidence that the Trilobites possessed the two pairs
+of jointed feelers ("antennæ") which are so characteristic
+of recent Crustaceans.
+</p>
+
+<p class="indent">
+The Trilobites vary much in size, and the Cambrian formation
+presents examples of both the largest and the smallest members
+of the order. Some of the young forms may be little bigger than
+a millet-seed, and some adult examples of the smaller species
+(such as <i>Agnostus</i>) may be only a few lines in length;
+whilst such giants of the order as <i>Paradoxides</i> and
+<i>Asaphus</i> may reach a length of from one to two feet. Judging
+from what we actually know as to the structure of the Trilobites,
+and also from analogous recent forms, it would seem that these
+ancient Crustaceans were mud-haunting creatures, denizens of
+shallow seas, and affecting the soft silt of the bottom rather
+than the clear water above. Whenever muddy sediments are found
+in the Cambrian and Silurian formations, there we are tolerably
+sure to find Trilobites, though they are by no means absolutely
+wanting in limestones. They appear to have crawled out upon the
+sea-bottom, or burrowed in the yielding mud, with the soft under
+surface directed downwards; and it is probable that they really
+derived their nutriment from the organic matter contained in the
+ooze amongst which they
+<a name="page_87"><span class="page">Page 87</span></a>
+lived. The vital
+organs seem to have occupied the central lobe of the skeleton,
+by which they were protected; and a series of delicate leaf-like
+paddles, which probably served as respiratory organs, would appear
+to have been carried on the under surface of the thorax. That
+they had their enemies may be regarded as certain; but we have no
+evidence that they were furnished with any offensive weapons, or,
+indeed, with any means of defence beyond their hard crust, and
+the power, possessed by so many of them, of rolling themselves
+into a ball. An additional proof of the fact that they for the
+most part crawled along the sea-bottom is found in the occurrence
+of tracks and markings of various kinds, which can hardly be
+ascribed to any other creatures with any show of probability.
+That this is the true nature of some of the markings in question
+cannot be doubted at all; and in other cases no explanation so
+probable has yet been suggested. If, however, the tracks which
+have been described from the Potsdam Sandstone of North America
+under the name of <i>Protichnites</i> are really due to the
+peregrinations of some Trilobite, they must have been produced
+by one of the largest examples of the order.
+</p>
+
+<p class="indent">
+As already said, the Cambrian Rocks are very rich in the remains
+of Trilobites. In the lowest beds of the series (Longmynd Rocks),
+representatives of some half-dozen genera have now been detected,
+including the dwarf <i>Agnostus</i> and the giant <i>Paradoxides</i>.
+In the higher beds, the number both of genera and species is
+largely increased; and from the great comparative abundance of
+individuals, the Trilobites have every right to be considered as
+the most characteristic fossils of the Cambrian period,&mdash;the
+more so as the Cambrian species belong to peculiar types, which,
+for the most part, died out before the commencement of the Silurian
+epoch.
+</p>
+
+<p class="indent">
+All the remaining Cambrian fossils which demand any notice here
+are members of one or other division of the great class of the
+<i>Mollusca</i>, or "Shell-fish" properly so called. In the Lower
+Cambrian Rocks the Lamp-shells (<i>Brachiopoda</i>) are the principal
+or sole representatives of the class, and appear chiefly in three
+interesting and important types&mdash;namely, <i>Lingulella,
+Discina,</i> and <i>Obolella</i>. Of these the last (fig. 32,
+<i>i</i>) is highly characteristic of these ancient deposits;
+whilst <i>Discina</i> is one of those remarkable persistent types
+which, commencing at this early period, has continued to be
+represented by varying forms through all the intervening geological
+formations up to the present day. <i>Lingulella</i> (fig. 32,
+<i>c</i>), again, is closely allied to the existing "Goose-bill"
+Lamp-shell (<i>Lingula anatina</i>), and thus presents us with
+another example of an extremely long-lived
+<a name="page_88"><span class="page">Page 88</span></a>
+type. The <i>Lingulellœ</i> and their successors; the
+<i>Lingulœ</i>, are singular in possessing a shell which
+is of a horny texture, and contains but a small proportion of
+calcareous matter. In the Upper Cambrian Rocks, the
+<i>Lingulellœ</i> become much more abundant, the broad
+satchel-shaped species known as <i>L. Davisii</i> (fig. 32, <i>e</i>)
+being so abundant that one of the great divisions of the Cambrian
+is termed the "Lingula Flags." Here, also, we meet for the first
+time with examples of the genus Orthis (fig. 32, <i>f, k, l</i>)
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 505px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig032.jpg" width="497" height="355" alt="Fig. 32" />
+<br />
+Fig. 32.&mdash;Cambrian Fossils: <i>a, Protospongia
+fenestrata</i>, Menevian Group; <i>b, Arenicolites didymus</i>,
+Longmynd Group; <i>c, Lingulella ferruginea</i>, Longmynd and
+Menevian, enlarged; <i>d, Hymenocaris vermicauda</i>, Lingula
+Flags; <i>e, Lingulella Davisii</i>, Lingula Flags; <i>f, Orthis
+lenticularis</i>, Lingula Flags; <i>g, Theca Davidii</i>, Tremadoc
+Slates; <i>h, Modiolopsis Solvensis</i>, Tremadoc Slates; <i>i,
+Obolela sagittalis</i>, interior of valve, Menevian; <i>j,</i>
+Exterior of the same; <i>k, Orthis Hicksii</i>, Menevian; <i>l</i>,
+Cast of the same; <i>m, Olenus micrurus</i>, Lingula Flags. (Alter
+Salter, Hicks, and Davidson.)
+</span>
+</span>
+
+a characteristic Palæozoic type of the Brachiopods, which is
+destined to undergo a vast extension in later ages.
+</p>
+
+<p class="indent">
+Of the higher groups of the <i>Mollusca</i> the record is as yet
+but scanty. In the Lower Cambrian, we have but the thin, fragile,
+dagger-shaped shells of the free-swimming oceanic Molluscs or
+"Winged-snails" (<i>Pteropoda</i>), of which the most characteristic
+is the genus <i>Theca</i> (fig. 32, <i>g</i>). In the Upper Cambrian,
+in addition to these, we have a few Univalves (<i>Gasteropoda</i>),
+and, thanks to the researches of Dr Hicks, quite a small assemblage
+of Bivalves (<i>Lamellibranchiata</i>), though these are mostly
+of no great dimensions (fig. 32, <i>h</i>). Of the chambered
+<i>Cephalopoda</i> (Cuttle-fishes and their allies), we have but
+<a name="page_89"><span class="page">Page 89</span></a>
+few traces; and these wholly confined to the higher beds of the
+formation. We meet, however, with examples of the wonderful genus
+
+<span style="float: right; margin: 4px; width: 128px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig033.jpg" width="120" height="240" alt="Fig. 33" />
+<br />
+Fig. 33.&mdash;Fragment of <i>Dictyonema sociale</i>,
+considerably enlarged, showing the horny branches, with their
+connecting cross-bars, and with a row of cells on each side.
+(Original.)
+</span>
+
+<i>Orthoceras</i>, with its straight, partitioned shell, which we
+shall find in an immense variety of forms in the Silurian rocks.
+Lastly, it is worthy of note that the lowest of all the groups of
+the <i>Mollusca</i>&mdash;namely, that of the Sea-mats, Sea-mosses,
+and Lace-corals (<i>Polyzoa</i>)&mdash;is only doubtfully known to
+have any representatives in the Cambrian, though undergoing a
+large and varied development in the Silurian deposits.
+</p>
+
+<p class="indent">
+An exception, however, may with much probability be made to this
+statement in favour of the singular genus <i>Dictyonema</i> (fig.
+33), which is highly characteristic of the highest Cambrian beds
+(Tremadoc Slates). This curious fossil occurs in the form of
+fan-like or funnel-shaped expansions, composed of slightly-diverging
+horny branches, which are united in a net-like manner by numerous
+delicate cross-bars, and exhibit a row of little cups or cells, in
+which the animals were contained, on each side. <i>Dictyonema</i>
+has generally been referred to the <i>Graptolites</i>; but it
+has a much greater affinity with the plant-like Sea-firs
+(<i>Sertularians</i>) or the Sea-mosses (<i>Polyzoa</i>), and
+the balance of evidence is perhaps in favour of placing it with
+the latter.
+</p>
+
+<h4 style="clear: right;">LITERATURE.</h4>
+
+<p class="indent">
+The following are the more important and accessible works and
+memoirs which may be consulted in studying the stratigraphical
+and palæontological relations of the Cambrian Rocks:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Siluria.' Sir Roderick Murchison. 5th ed., pp. 21-46.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Synopsis of the Classification of the British Palæozoic
+Rocks.' Sedgwick. Introduction to the 3d Fasciculus of the
+'Descriptions of British Palæozoic Fossils in the Woodwardian
+Museum,' by F. M'Coy, pp. i-xcviii, 1855.</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Catalogue of the Cambrian and Silurian Fossils in the Geological
+Museum of the University of Cambridge.' Salter. With a Preface
+by Prof. Sedgwick. 1873.</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>'Thesaurus Siluricus.' Bigsby. 1868.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>"History of the Names Cambrian and Silurian." Sterry
+Hunt.&mdash;'Geological Magazine.' 1873.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>'Système Silurien du Centre de la Bohême.' Barrande.
+  Vol. I.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>'Report of Progress of the Geological Survey of Canada, from
+its Commencement to 1863,' pp. 87-109.</td></tr>
+<tr><td class="right" valign="top">(8)
+<a name="page_90"><span class="page">Page 90</span></a></td>
+ <td>'Acadian Geology.' Dawson. Pp. 641-657.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>"Guide to the Geology of New York," Lincklaen; and "Contributions
+to the Palæontology of New York," James Hall.&mdash;'Fourteenth
+Report on the State Cabinet.' 1861.</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Palæozoic Fossils of Canada.' Billings. 1865.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'Manual of Geology.' Dana. Pp. 166-182. 2d ed. 1875.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>"Geology of North Wales," Ramsay; with Appendix on the
+Fossils, Salter.&mdash;'Memoirs of the Geological Survey of Great
+Britain,' vol. iii. 1866.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>"On the Ancient Rocks of the St David's Promontory, South
+Wales, and their Fossil Contents." Harkness and Hicks.&mdash;'Quart.
+Journ. Geol. Soc.,' xxvii. 384-402. 1871.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>"On the Tremadoc Rocks in the Neighbourhood of St David's,
+South Wales, and their Fossil Contents." Hicks.&mdash;'Quart.
+Journ. Geol. Soc.,' xxix. 39-52. 1873.</td></tr>
+</table>
+
+<p class="indent">
+In the above list, allusion has necessarily been omitted to numerous
+works and memoirs on the Cambrian deposits of Sweden and Norway,
+Central Europe, Russia, Spain, and various parts of North America,
+as well as to a number of important papers on the British Cambrian
+strata by various well-known observers. Amongst these latter
+may be mentioned memoirs by Prof. Phillips, and Messrs Salter,
+Hicks, Belt, Plant, Homfray, Ash, Holl, &amp;c.
+</p>
+
+<h3>CHAPTER IX.</h3>
+
+<p class="subtitle">
+THE LOWER SILURIAN PERIOD.
+</p>
+
+<p class="indent">
+The great system of deposits to which Sir Roderick Murchison
+applied the name of "Silurian Rocks" reposes directly upon the
+highest Cambrian beds, apparently without any marked unconformity,
+though with a considerable change in the nature of the fossils. The
+name "Silurian" was originally proposed by the eminent geologist
+just alluded to for a great series of strata lying below the Old
+Red Sandstone, and occupying districts in Wales and its borders
+which were at one time inhabited by the "Silures," a tribe of
+ancient Britons. Deposits of a corresponding age are now known
+to be largely developed in other parts of England, in Scotland,
+and in Ireland, in North America, in Australia, in India, in
+Bohemia, Saxony, Bavaria, Russia, Sweden and Norway, Spain, and
+in various other regions of less note. In some regions, as in
+the neighbourhood of St Petersburg, the Silurian strata are found
+not only to have preserved their original horizontality, but
+also to have retained almost unaltered their primitive soft and
+incoherent nature. In other regions, as in Scandinavia and many
+<a name="page_91"><span class="page">Page 91</span></a>
+parts of North America, similar strata, now
+consolidated into shales, sandstones, and limestones, may be
+found resting with a very slight inclination on still older
+sediments. In a great many regions, however, the Silurian
+deposits are found to have undergone more or less folding,
+crumpling, and dislocation, accompanied by induration and
+"cleavage" of the finer and softer sediments; whilst in some
+regions, as in the Highlands of Scotland, actual "metamorphism"
+has taken place. In consequence of the above, Silurian districts
+usually present the bold, rugged, and picturesque outlines which
+are characteristic of the older "Primitive" rocks of the earth's
+crust in general. In many instances, we find Silurian strata
+rising into mountain-chains of great grandeur and sublimity,
+exhibiting the utmost diversity of which rock-scenery is capable,
+and delighting the artist with endless changes of valley, lake,
+and cliff. Such districts are little suitable for agriculture,
+though this is often compensated for by the valuable mineral
+products contained in the rocks. On the other hand, when the
+rocks are tolerably soft and uniform in their nature, or when
+few disturbances of the crust of the earth have taken place, we
+may find Silurian areas to be covered with an abundant pasturage
+or to be heavily timbered.
+</p>
+
+<p class="indent">
+Under the head of "Silurian Rocks," Sir Roderick Murchison included
+all the strata between the summit of the "Longmynd." beds and
+the Old Red Sandstone, and he divided these into the two great
+groups of the <i>Lower</i> Silurian and <i>Upper</i> Silurian. It
+is, however, now generally admitted that a considerable portion
+of the basement beds of Murchison's Silurian series must be
+transferred&mdash;if only upon palæontological grounds&mdash;to
+the Upper Cambrian, as has here been done; and much controversy has
+been carried on as to the proper nomenclature of the Upper Silurian
+and of the remaining portion of Murchison's Lower Silurian. Thus,
+some would confine the name "Silurian" exclusively to the Upper
+Silurian, and would apply the name of "Cambro-Silurian" to the
+Lower Silurian, or would include all beds of the latter age in the
+"Cambrian" series of Sedgwick. It is not necessary to enter into
+the merits of these conflicting views. For our present purpose,
+it is sufficient to recognise that there exist two great groups
+of rocks between the highest Cambrian beds, as here defined, and
+the base of the Devonian or Old Red Sandstone. These two great
+groups are so closely allied to one another, both physically
+and palæontologically, that many authorities have established
+a third or intermediate group (the "Middle Silurian"), by which a
+<a name="page_92"><span class="page">Page 92</span></a>
+passage is made from one into the other. This
+method of procedure involves disadvantages which appear to outweigh
+its advantages; and the two groups in question are not only
+generally capable of very distinct stratigraphical separation,
+but at the same time exhibit, together with the alliances above
+spoken of, so many and such important palæontological
+differences, that it is best to consider them separately. We
+shall therefore follow this course in the present instance; and
+pending the final solution of the controversy as to Cambrian and
+Silurian nomenclature, we shall distinguish these two groups of
+strata as the "Lower Silurian" and the "Upper Silurian."
+</p>
+
+<p class="indent">
+The <i>Lower Silurian Rocks</i> are known already to be developed
+in various regions; and though their <i>general</i> succession
+in these areas is approximately the same, each area exhibits
+peculiarities of its own, whilst the subdivisions of each are
+known by special names. All, therefore, that can be attempted
+here, is to select two typical areas&mdash;such as Wales and
+North America and to briefly consider the grouping and divisions
+of the Lower Silurian in each.
+</p>
+
+<p class="indent">
+In Wales, the line between the Cambrian and Lower Silurian is
+somewhat ill-defined, and is certainly not marked by any strong
+unconformity. There are, however; grounds for accepting the line
+proposed, for palæontological reasons, by Dr Hicks, in accordance
+with which the Tremadoc Slates ("Lower Tremadoc" of Salter) become
+the highest of the Cambrian deposits of Britain. If we take this
+view, the Lower Silurian rocks of Wales and adjoining districts
+are found to have the following <i>general</i> succession from
+below upwards (fig. 34):&mdash;
+</p>
+
+<p class="indent">
+1. The <i>Arenig Group</i>.&mdash;This group derives its name from
+the Arenig mountains, where it is extensively developed. It consists
+of about 4000 feet of slates, shales, and flags, and is divisible
+into a lower, middle, and upper division, of which the former
+is often regarded as Cambrian under the name of "Upper Tremadoc
+Slates."
+</p>
+
+<p class="indent">
+2. The <i>Llandeilo Group</i>.&mdash;The thickness of this group
+varies from about 4000 to as much as 10,000 feet; but in this
+latter case a great amount of the thickness is made up of volcanic
+ashes and interbedded traps. The sedimentary beds of this group
+are principally slates and flags, the latter occasionally with
+calcareous bands; and the whole series can be divided into a
+lower, middle, and upper Llandeilo division, of which the last
+is the most important. The name of "Llandeilo" is derived from
+the town of the same name in Wales, where strata of this age
+were described by Murchison.
+</p>
+
+<p class="indent">
+<a name="page_93"><span class="page">Page 93</span></a>
+3. The <i>Caradoc</i> or <i>Bala Group</i>.&mdash;The alternative
+names of this group are also of local origin, and are derived,
+the one from Caer Caradoc in Shropshire, the other from Bala
+in Wales, strata of this age occurring in both localities. The
+series is divided into a lower and upper group, the latter chiefly
+composed of shales and flags, and the former of sandstones and
+shales, together with the important and interesting calcareous
+band known as the "Bala Limestone." The thickness of the entire
+series varies from 4000 to as much as 12,000 feet, according
+as it contains more or less of interstratified igneous rocks.
+</p>
+
+<p class="indent">
+4. The <i>Llandovery Group</i> (Lower Llandovery of
+Murchison).&mdash;This series, as developed near the town of
+Llandovery, in Caermarthenshire, consists of less than 1000 feet
+of conglomerates, sandstones, and shales. It is probable, however,
+that the little calcareous band known as the "Hirnant Limestone,"
+together with certain pale-coloured slates which lie above the
+Bala Limestone, though usually referred to the Caradoc series,
+should in reality be regarded as belonging to the Llandovery group.
+</p>
+
+<p class="indent">
+The general succession of the Lower Silurian strata of Wales
+and its borders, attaining a maximum thickness (along with
+contemporaneous igneous matter) of nearly 30,000 feet, is
+diagramatically represented in the annexed sketch-section (fig.
+34):&mdash;
+</p>
+
+<p class="indent">
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 549px;
+  font-size: smaller; text-align: center;">
+<a name="page_94"><span class="page">Page 94</span></a>
+GENERALIZED SECTION OF THE LOWER SILURIAN ROCKS OF WALES.
+<br />
+Fig. 34.
+<br />
+<img src="images/fig034.jpg" width="541" height="761" alt="Fig. 34" />
+</span>
+</span>
+In North America, both in the United States and in Canada, the
+Silurian rocks are very largely developed, and may be
+<a name="page_95"><span class="page">Page 95</span></a>
+regarded as constituting an exceedingly full and
+typical series of the deposits of this period. The chief groups
+of the Silurian rocks of North America are as follows, beginning,
+as before, with the lowest strata, and proceeding upwards (fig.
+35):&mdash;
+</p>
+
+<p class="indent">
+1. <i>Quebec Group</i>.&mdash;This group is typically developed in
+the vicinity of Quebec, where it consists of about 5000 feet of
+strata, chiefly variously-coloured shales, together with some
+sandstones and a few calcareous bands. It contains a number of
+peculiar Graptolites, by which it can be identified without
+question with the Arenig group of Wales and the corresponding
+Skiddaw Slates of the North of England. It is also to be noted
+that numerous Trilobites of a distinct Cambrian <i>facies</i>
+have been obtained in the limestones of the Quebec group, near
+Quebec. These fossils, however, have been exclusively obtained
+from the limestones of the group; and as these limestones are
+principally calcareous breccias or conglomerates, there is room
+for believing that these primordial fossils are really derived,
+in part at any rate, from fragments of an upper Cambrian
+limestone. In the State of New York, the Graptolitic shales of
+Quebec are wanting; and the base of the Silurian is constituted
+by the so-called "Calciferous Sand-rock" and "Chazy
+Limestone."[11] The first of these is essentially and typically
+calcareous, and the second is a genuine limestone.
+</p>
+
+<p class="footnote">
+[Footnote 11: The precise relations of the Quebec shales with
+Graptolites (Levis Formation) to the Calciferous and Chazy beds
+are still obscure, though there seems little doubt but that the
+Quebec Shales are superior to the Calciferous Sand-rock.]
+</p>
+
+<p class="indent">
+2. The <i>Trenton Group</i>.&mdash;This is an essentially calcareous
+group, the various limestones of which it is composed being known
+as the "Bird's-eye," "Black River," and "Trenton" Limestones, of
+which the last is the thickest and most important. The thickness
+of this group is variable, and the bands of limestone in it are
+often separated by beds of shale.
+</p>
+
+<p class="indent">
+3. The <i>Cincinnati Group</i> (Hudson River
+Formation[12]).&mdash;This group consists essentially of a lower
+series of shales, often black in colour and highly charged with
+bituminous matter (the "Utica Slates "), and of an upper series
+of shales, sandstones,
+<a name="page_96"><span class="page">Page 96</span></a>
+and limestones (the
+"Cincinnati" rocks proper). The exact parallelism of the
+Trenton and Cincinnati groups with the subdivisions of the Welsh
+Silurian series can hardly be stated positively. Probably no
+precise equivalency exists; but there can be no doubt but that
+the Trenton and Cincinnati groups correspond, as a whole, with
+the Llandeilo and Caradoc groups of Britain. The subjoined
+diagrammatic section (fig. 35) gives a general idea of the
+succession of the Lower Silurian rocks of North America:&mdash;
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+GENERALIZED SECTION OF THE LOWER SILURIAN ROCKS OF NORTH AMERICA.
+<br />
+Fig. 35.
+<br />
+<img src="images/fig035.jpg" width="549" height="661" alt="Fig. 35" />
+</span>
+</span>
+</p>
+
+<p class="footnote">
+[Footnote 12: There is some difficulty about the precise nomenclature
+of this group. It was originally called the "Hudson River Formation;"
+but this name is inappropriate, as rocks of this age hardly touch
+anywhere the actual Hudson River itself, the rocks so called
+formerly being now known to be of more ancient date. There is
+also some want of propriety in the name of "Cincinnati Group,"
+since the rocks which are known under this name in the vicinity of
+Cincinnati itself are the representatives of the Trenton Limestone,
+Utica Slates, and the old Hudson River group, inseparably united
+in what used to be called the "Blue Limestone Series."].
+</p>
+
+<p class="indent">
+<a name="page_97"><span class="page">Page 97</span></a>
+Of the <i>life</i> of the Lower Silurian period we have record
+in a vast number of fossils, showing that the seas of this period
+were abundantly furnished with living denizens. We have, however,
+in the meanwhile, no knowledge of the land-surfaces of the period.
+We have therefore no means of speculating as to the nature of
+the terrestrial animals of this ancient age, nor is anything
+known with certainty of any land-plants which may have existed.
+The only relics of vegetation upon which a positive opinion can
+be expressed belong to the obscure group of the "Fucoids," and
+are supposed to be the remains of sea-weeds. Some of the fossils
+usually placed under this head are probably not of a vegetable
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 412px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig036.jpg" width="406" height="539" alt="Fig. 36" />
+<br />
+Fig. 36.&mdash;<i>Licrophycus Ottawaensis</i> a "Fucoid," from the
+Trenton Limestone (Lower Silurian) of Canada. (After Billings.)
+</span>
+</span>
+
+nature at all, but others (fig. 36) appear to be unquestionable
+plants. The true affinities of these, however, are extremely
+dubious. All that can be said is, that remains which appear to
+be certainly vegetable,
+<a name="page_98"><span class="page">Page 98</span></a>
+and which are most
+probably due to marine plants, have been recognised nearly at
+the base of the Lower Silurian (Arenig), and that they are found
+throughout the series whenever suitable conditions recur.
+</p>
+
+<p class="indent">
+The Protozoans appear to have flourished extensively in the Lower
+Silurian seas, though to a large extent under forms which are
+still little understood. We have here for the first time the
+appearance of Foraminifera of the ordinary type&mdash;one of the
+most interesting observations in this collection being that made
+by Ehrenberg, who showed that the Lower Silurian sandstones of
+the neighbourhood of St Petersburg contained casts in glauconite
+of Foraminiferous shells, some of which are referable to the
+existing genera <i>Rotalia</i> and <i>Texularia</i>. True
+<i>Sponges</i>, belonging to that section of the group in which
+the skeleton is calcareous, are also not unknown, one of the
+
+<span style="float: left; margin: 4px; width: 263px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig037.jpg" width="255" height="253" alt="Fig. 37" />
+<br />
+Fig. 37.&mdash;<i>Astylospongia prœmorsa</i>, cut
+vertically so as to exhibit the canal-system in the interior.
+Lower Silurian, Tennessee. (After Ferdinand Rœmer.)
+</span>
+
+most characteristic genera being <i>Astylospongia</i> (fig. 37).
+In this genus are included more or less globular, often lobed
+sponges, which are believed not to have been attached to foreign
+bodies. In the form here figured there is a funnel-shaped cavity
+at the summit; and the entire mass of the sponge is perforated,
+as in living examples, by a system of canals which convey the
+sea-water to all parts of the organism. The canals by which the
+sea-water gains entrance open on the exterior of the sphere,
+and those by which it again escapes from the sponge open into
+the cup-shaped depression at the summit.
+</p>
+
+<p class="indent">
+The most abundant, and at the same time the least understood,
+of Lower Silurian Protozoans belong, however, to the genera
+<i>Stromatopora</i> and <i>Receptaculites</i>, the structure
+of which can merely be alluded to here. The specimens of
+<i>Stromatopora</i> (fig. 38) occur as hemispherical, pear-shaped,
+globular, or irregular masses, often of very considerable size,
+and sometimes demonstrably attached to foreign bodies. In their
+structure these masses consist of numerous thin calcareous
+laminæ, usually arranged concentrically, and separated by
+narrow interspaces. These interspaces are generally crossed by
+numerous vertical calcareous pillars, giving the
+<a name="page_99"><span class="page">Page 99</span></a>
+vertical section of the fossil a
+lattice-like appearance. There are also usually minute pores in the
+concentric laminæ, by which the successive interspaces are
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 454px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig038.jpg" width="446" height="408" alt="Fig. 38" />
+<br />
+Fig. 38.&mdash;A small and perfect specimen of <i>Stromatopora
+rugosa</i>, of the natural size, from the Trenton Limestone of
+Canada. (After Billings.)
+</span>
+</span>
+
+placed in communication; and sometimes the surface presents large
+rounded openings, which appear to correspond with the water-canals
+of the Sponges. Upon the whole, though presenting some curious
+affinities to the calcareous Sponges, <i>Stromatopora</i> is
+perhaps more properly regarded as a gigantic <i>Foraminifer</i>. If
+this view be correct, it is of special interest as being probably the
+nearest ally of <i>Eozoön</i>, the general appearance of the two
+being strikingly similar, though their minute structure is not at
+all the same. Lastly, in the fossils known as <i>Receptaculites</i>
+and <i>Ischadites</i> we are also presented with certain singular
+Lower Silurian Protozoans, which may with great probability be
+regarded as gigantic <i>Foraminifera</i>. Their structure is very
+complex; but fragments are easily recognised by the fact that the
+exterior is covered with numerous rhomboidal calcareous plates,
+closely fitting together, and arranged in peculiar intersecting
+curves, presenting very much the appearance of the engine-turned
+case of a watch.
+</p>
+
+<p class="indent">
+Passing next to the sub-kingdom of <i>Cœlenterate</i> animals
+(Zoophytes, Corals, &amp;c.), we find that this great group, almost
+or wholly absent in the Cambrian, is represented in Lower
+<a name="page_100"><span class="page">Page 100</span></a>
+Silurian deposits by a great number of forms belonging
+on the one hand to the true Corals, and en the other hand to the
+singular family of the <i>Graptolites</i>. If we except certain
+plant-like fossils which probably belong rather to the Sertularians
+or the Polyzoans (e.g., <i>Dictyonema, Dendrograptus</i>, &amp;c.),
+the family of the <i>Graptolites</i> may be regarded as exclusively
+Silurian in its distribution. Not only is this the case, but it
+attained its maximum development almost upon its first appearance,
+in the Arenig Rocks; and whilst represented by a great variety of
+types in the Lower Silurian; it only exists in the Upper Silurian
+in a much diminished form. The <i>Graptolites</i> (Gr. <i>grapho</i>,
+I write; <i>lithos</i>, stone) were so named by Linnæus, from
+the resemblance of some of them to written or pencilled marks upon
+the stone, though the great naturalist himself did not believe
+them to be true fossils at all. They occur as linear or leaf-like
+bodies, sometimes simple, sometimes compound and branched; and no
+doubt whatever can be entertained as to their being the skeletons
+of composite organisms, or colonies of semi-independent animals
+united together by a common fleshy trunk, similar to what is
+observed in the colonies of the existing Sea-firs (Sertularians).
+This fleshy trunk or common stem of the colony was protected
+by a delicate horny sheath, and it gave origin to the little
+flower-like "polypites," which constituted the active element of
+the whole assemblage. These semi-independent beings were, in turn,
+protected each by a little horny cup or cell, directly connected
+with the common sheath below, and terminating above in an opening
+through which the polypite could protrude its tentacled head or
+could again withdraw itself for safety. The entire skeleton,
+again, was usually, if not universally, supported by a delicate
+horny rod or "axis," which appears to have been hollow, and which
+often protrudes to a greater or less extent beyond one or both
+of the extremities of the actual colony.
+</p>
+
+<p class="indent">
+The above gives the elementary constitution of any <i>Graptolite</i>,
+but there are considerable differences as to the manner in which
+these elements are arranged and combined. In some forms the common
+stem of the colony gives origin to but a single row of cells
+on one side. If the common stem is a simple, straight, or
+slightly-curved linear body, then we have the simplest form of
+Graptolite known (the genus <i>Monograptus</i>); and it is worthy
+of note that these simple types do not come into existence till
+comparatively late (Llandeilo), and last nearly to the very close
+of the Upper Silurian. In other cases, whilst there is still but
+a single row of cells, the colony may consist of two of these
+simple stems springing from a
+<a name="page_101"><span class="page">Page 101</span></a>
+common point, as in the so-called
+"twin Graptolites" (<i>Didymograptus</i>, fig. 40). This type is
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 551px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig039.jpg" width="543" height="610" alt="Fig. 39" />
+<br />
+Fig. 39.&mdash;<i>Dichograptus octobrachiatus</i>, a branched,
+"unicellular" Graptolite from the Skiddaw and Quebec Groups
+(Arenig). (After Hall.)
+</span>
+</span>
+
+entirely confined to the earlier portion of the Lower Silurian period
+(Arenig and Llandeilo). In other cases, again, there may be four of
+such stems springing from a central point (<i>Tetragraptus</i>).
+Lastly, there are numerous complex forms (such as <i>Dichograptus,
+Loganograptus</i>, &amp;c.) in which there are eight or more of these
+simple branches, all arising from a common centre (fig. 39),
+which is sometimes furnished with a singular horny disc. These
+complicated branching forms, as well as the <i>Tetragrapti</i>,
+are characteristic of the horizon of the Arenig group. Similar
+forms, often specifically identical, are found at this horizon
+in Wales, in the great series of the Skiddaw Slates of the north
+of England, in the Quebec group in Canada, in equivalent beds in
+Sweden, and in certain gold-bearing slates of the same age in
+Victoria in Australia.
+</p>
+
+<p class="indent">
+In another great group of Graptolites (including the genera
+<i>Diplograptus, Dicranograptus, Climacograptus</i>, &amp;c.) the
+common stem of the colony gives origin, over part or the whole or
+its length, to <i>two</i> rows of cells, one on each side (fig. 41).
+These "double-celled" Graptolites are highly characteristic of the
+Lower Silurian deposits; and, with an exception more apparent than
+<a name="page_102"><span class="page">Page 102</span></a>
+real in Bohemia, they are exclusively confined to strata of Lower
+Silurian age, and are not known to occur in the Upper Silurian.
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 582px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig040.jpg" width="574" height="217" alt="Fig. 40" />
+<br />
+Fig. 40.&mdash;Central portion of the colony of <i>Didymegraptus
+divaricatus</i>, Upper Llandeilo, Dumfresshire. (Original.)
+</span>
+</span>
+
+Lastly, there is a group of Graptolites (<i>Phyllograptus</i>, fig.
+42) in which the colony is leaf-like in form, and is composed
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 235px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig041.jpg" width="227" height="460" alt="Fig. 41" />
+<br />
+Fig. 41.&mdash;Examples of <i>Diplograptus pristis</i>,
+showing variations in the appendages at the base. Upper Llandeilo,
+Dumfriesshire. (Original.)
+</span>
+
+<span style="width: 276px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig042.jpg" width="268" height="383" alt="Fig. 42" />
+<br />
+Fig. 42.&mdash;Group of individuals of <i>Phyllograptus
+typus</i>, from the Quebec group of Canada. (After Hall.) One
+of the four rows of cells is hidden on the under surface.
+</span>
+
+</span>
+
+of <i>four</i> rows of cells springing in a cross-like
+<a name="page_103"><span class="page">Page 103</span></a>
+manner from the common stem. These forms are highly
+characteristic of the Arenig group.
+</p>
+
+<p class="indent">
+The Graptolites are usually found in dark-coloured, often black
+shales, which sometimes contain so much carbon as to become
+"anthracitic." They may be simply carbonaceous; but they are
+more commonly converted into iron-pyrites, when they glitter
+with the brilliant lustre of silver as they lie scattered on the
+surface of the rock, fully deserving in their metallic tracery
+the name of "written stones." They constitute one of the most
+important groups of Silurian fossils, and are of the greatest
+value in determining the precise stratigraphical position of
+the beds in which they occur. They present, however, special
+difficulties in their study; and it is still a moot point as
+to their precise position in the zoological scale. The balance
+of evidence is in favour of regarding them as an ancient and
+peculiar group of the Sea-firs (Hydroid Zoophytes), but some
+regard them as belonging rather to the Sea-mosses (<i>Polyzoa</i>).
+Under any circumstances, they cannot be directly compared either
+with the ordinary Sea-firs or the ordinary Sea-mosses; for these
+two groups consist of fixed organisms, whereas the Graptolites
+were certainly free-floating creatures, living at large in the
+open sea. The only Hydroid Zoophytes or Polyzoans which have
+a similar free mode of existence, have either no skeleton at
+all, or have hard structures quite unlike the horny sheaths of
+the Graptolites.
+</p>
+
+<p class="indent">
+The second great group of Cœlenterate animals
+(<i>Actinozoa</i>) is represented in the Lower Silurian rocks
+by numerous Corals. These, for obvious reasons, are much more
+abundant in regions where the Lower Silurian series is largely
+calcareous (as in North America) than in districts like Wales,
+where limestones are very feebly developed. The Lower Silurian
+Corals, though the first of their class, and presenting certain
+peculiarities, may be regarded as essentially similar in nature
+to existing Corals. These, as is well known, are the calcareous
+skeletons of animals&mdash;the so-called
+"Coral-Zoophytes"&mdash;closely allied to the common Sea-anemones
+in structure and habit. A <i>simple</i> coral (fig. 43) consists
+of a calcareous cup embedded in the soft tissues of the
+flower-like polype, and having at its summit a more or less deep
+depression (the "calice") in which the digestive organs are
+contained. The space within the coral is divided into compartments
+by numerous vertical calcareous plates (the "septa"), which spring
+from the inside of the wall of the cup, and of which some generally
+reach the centre. <i>Compound</i> corals, again (fig. 44), consist
+of a greater or less number of structures similar in structure
+to the above,
+<a name="page_104"><span class="page">Page 104</span></a>
+but united together in different
+ways into a common mass. <i>Simple</i> corals, therefore, are the
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 294px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig043.jpg" width="286" height="332" alt="Fig. 43" />
+<br />
+Fig. 43.&mdash;<i>Zaphrentis Stokesi</i>, a simple "cup-coral,"
+Upper Silurian, Canada. (After Billings.)
+</span>
+
+<span style="width: 265px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig044.jpg" width="257" height="202" alt="Fig. 44" />
+<br />
+Fig. 44.&mdash;Upper surface of a mass of <i>Strombodes
+pentagonus</i>. Upper Silurian, Canada. (After Billings.)
+</span>
+
+</span>
+
+skeletons of <i>single</i> and independent polypes; whilst
+<i>compound</i> corals are the skeletons of assemblages or
+colonies of similar polypes, living united with one another
+another as an organic community.
+</p>
+
+<p class="indent">
+In the general details of their structure, the Lower Silurian
+Corals do not differ from the ordinary Corals of the present
+day. The latter, however, have the vertical calcareous plates of
+the coral ("septa") arranged in multiples of six or five; whereas
+the former have these structures arranged in multiples of four,
+and often showing a cross-like disposition. For this reason, the
+common Lower Silurian Corals are separated to form a distinct
+group under the name of <i>Rugose</i> Corals or <i>Rugosa</i>.
+They are further distinguished by the fact that the cavity of
+the coral ("visceral chamber") is usually subdivided by more
+or less numerous horizontal calcareous plates or partitions,
+which divide the coral into so many tiers or storeys, and which
+are known as the "tabulæ" (fig. 45).
+</p>
+
+<p class="indent">
+In addition to the Rugose Corals, the Lower Silurian rocks contain
+a number of curious compound corals, the tubes of which have either
+no septa at all or merely rudimentary ones, but which have the
+transverse partitions or "tabulæ" very highly developed. These
+are known as the <i>Tabulate Corals</i>; and recent researches on
+some of their existing allies (such as <i>Heliopora</i>) have shown
+that they are really allied to
+<a name="page_105"><span class="page">Page 105</span></a>
+the modern Sea-pens, Organ-pipe
+Corals, and Red Coral, rather than to the typical stony Corals.
+Amongst the characteristic Rugose Corals of the Lower Silurian
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 381px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig045.jpg" width="373" height="260" alt="Fig. 45" />
+<br />
+Fig. 45.&mdash;<i>Columnaria alveolata</i>, a Rugose compound
+coral, with imperfect septa, but having the corallites partitioned
+off into storeys by "tabulæ." Lower Silurian, Canada. (After
+Billings.)
+</span>
+</span>
+
+may be mentioned species belonging to the genera <i>Columnaria,
+Favistella, Streptelasma</i>, and <i>Zaphrentis</i>; whilst amongst
+the "Tabulate" Corals, the principal forms belong to the genera
+<i>Chœtetes, Halysites</i> (the Chain-coral), <i>Constellaria</i>,
+and <i>Heliolites</i>. These groups of the Corals, however, attain
+a greater development at a later period, and they will be noticed
+more particularly hereafter.
+</p>
+
+<p class="footnote">
+[Footnote 13: The genus <i>Caryocrinus</i> is sometimes regarded
+as properly belonging to the <i>Crinoids</i>, but there seem to
+be good reasons for rather considering it as an abnormal form
+of <i>Cystidean</i>.]
+</p>
+
+<p class="indent">
+Passing onto higher animals, we find that the class of the
+<i>Echinodermata</i> is represented by examples of the Star-fishes
+(<i>Asteroidea</i>), the Sea-lilies (<i>Crinoidea</i>), and the
+peculiar extinct group of the Cystideans (<i>Cystoidea</i>), with
+one or two of the Brittle-stars (<i>Ophiuroidea</i>)&mdash;the
+Sea-urchins (<i>Echinoidea</i>) being still wanting. The Crinoids,
+though in some places extremely numerous, have not the varied
+development that they possess in the Upper Silurian, in connection
+with which their structure will be more fully spoken of. In the
+meanwhile, it is sufficient to note that many of the calcareous
+deposits of the Lower Silurian are strictly entitled to the name
+of "Crinoidal limestones," being composed in great part of the
+detached joints, and plates, and broken stems, of these beautiful
+but fragile organisms (see fig. 12). Allied to the Crinoids are
+the singular creatures which are known as <i>Cystideans</i> (fig.
+46). These are generally composed of a globular or ovate body
+(the "calyx"), supported upon a short stalk (the "column"), by
+which the organism was usually attached to some foreign body. The
+body was enclosed by closely-fitting calcareous plates, accurately
+<a name="page_106"><span class="page">Page 106</span></a>
+jointed together; and the stem was made up of numerous distinct
+pieces or joints, flexibly united to each other by membrane. The
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 503px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig046.jpg" width="495" height="419" alt="Fig. 46" />
+<br />
+Fig. 46.&mdash;Group of Cystideans. A, <i>Caryocrinus
+ornatus</i>,[13] Upper Silurian, America; B, <i>Pleurocystites
+squamosus</i>, showing two short "arms," Lower Silurian, Canada;
+C, <i>Pseudocrinus bifasciatus</i>, Upper Silurian, England; D,
+<i>Lepadocrinus Gebhartii</i>, Upper Silurian, America. (After
+Hall, Billings, and Salter.)
+</span>
+</span>
+
+chief distinction which strikes one in comparing the Cystideans
+with the Crinoids is, that the latter are always furnished, as
+will be subsequently seen, with a beautiful crown of branched
+and feathery appendages, springing from the summit of the calyx,
+and which are composed of innumerable calcareous plates or joints,
+and are known as the "arms." In the Cystideans, on the other hand,
+there are either no "arms" at all, or merely short, unbranched,
+rudimentary arms. The Cystideans are principally, and indeed
+nearly exclusively, Silurian fossils; and though occurring in
+the Upper Silurian in no small numbers, they are pre-eminently
+characteristic of the Llandeilo-Caradoc period of Lower Silurian
+time. They commenced their existence, so far as known, in the
+Upper Cambrian; and though examples are not absolutely unknown
+<a name="page_107"><span class="page">Page 107</span></a>
+in later periods, they are pre-eminently characteristic of the
+earlier portion of the Palæozoic
+epoch.
+</p>
+
+<p class="indent">
+The Ringed Worms (<i>Annelides</i>) are abundantly represented
+in the Lower Silurian, but principally by tracks and burrows
+similar in essential respects to those which occur so commonly
+in the Cambrian formation, and calling for no special comment.
+Much more important are the <i>Articulate</i> animals, represented
+as heretofore, wholly by the remains of the aquatic group of the
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig047.jpg" width="551" height="585" alt="Fig. 47" />
+<br />
+Fig. 47.&mdash;Lower Silurian Crustaceans. <i>a, Asaphus
+tyrannus</i>, Upper Llandeilo; <i>b. Ogygia Buchii</i>, Upper
+Llandeilo; <i>c, Trinucleus concentricus</i>, Caradoc; <i>d,
+Caryocaris Wrightii</i>, Arenig (Skiddaw Slates); <i>e, Beyrichia
+complicata</i>, natural size and enlarged, Upper Llandeilo and
+Caradoc; <i>f, Primitia strangulata</i>, Caradoc: <i>g.</i>
+Head-shield of <i>Calymene Blumenbachii</i>, var.
+<i>brevicapitata</i>, Caradoc; <i>h</i>, Head-shield of <i>Triarthrus
+Becki</i> (Utica Slates), United States: <i>i</i>, Shield of
+<i>Leperditia Canadensis</i>, var. <i>Josephiana</i>, of the
+natural size, Trenton Limestone, Canada; <i>j</i>, The same,
+viewed from the front. (After Salter, M'Coy, Rupert Jones, and
+Dana.)
+</span>
+</span>
+
+<i>Crustaceans</i>. Amongst these are numerous little bivalved
+forms&mdash;such as species of <i>Primitia</i> (fig. 47, <i>f</i>),
+<a name="page_108"><span class="page">Page 108</span></a>
+<i>Beyrichia</i> (fig. 47, <i>e</i>), and
+<i>Leperditia</i> (fig. 47, <i>i</i> and <i>j</i>). Most of these
+are very small, varying from the size of a pin's head up to that
+of a hemp seed; but they are sometimes as large as a small bean
+(fig. 47, <i>i</i>), and they are commonly found in myriads
+together in the rock. As before said, they belong to the same
+great group as the living Water-fleas (<i>Ostracoda</i>). Besides
+these, we find the pod-shaped head-shields of the shrimp-like
+Phyllopods&mdash;such as <i>Caryocaris</i> (fig. 47, <i>d</i>)
+and <i>Ceratiocaris</i>. More important, however, than any of
+these are the <i>Trilobites</i>, which may be considered as
+attaining their maximum development in the Lower Silurian. The
+huge <i>Paradoxides</i> of the Cambrian have now disappeared,
+and with them almost all the principal and characteristic
+"primordial" genera, save <i>Olenus</i> and <i>Agnostus</i>. In
+their place we have a great number of new forms&mdash;some of them,
+like the great <i>Asaphus tyrannus</i> of the Upper Llandeilo
+(fig. 47, <i>a</i>), attaining a length of a foot or more, and
+thus hardly yielding in the matter of size to their ancient rivals.
+Almost every subdivision of the Lower Silurian series has its own
+special and characteristic species of Trilobites; and the study
+of these is therefore of great importance to the geologist. A
+few widely-dispersed and characteristic species have been here
+figured (fig. 47); and the following may be considered as the
+principal Lower Silurian genera&mdash;<i>Asaphus, Ogygia, Cheirurus,
+Ampyx, Caiymene, Trinucleus, Lichas, Illœnus, Æglina,
+Harpes, Remopleurides, Phacops, Acidaspis</i>, and
+<i>Homalonotus</i>, a few of them passing upwards under new forms
+into the Upper Silurian.
+</p>
+
+<p class="indent">
+Coming next to the <i>Mollusca</i>, we find the group of the
+Sea-mosses and Sea-mats (<i>Polyzoa</i>) represented now by quite a
+number of forms. Amongst these are examples of the true Lace-corals
+(<i>Retepora</i> and <i>Fenestella</i>), with their netted fan-like
+or funnel-shaped fronds; and along with these are numerous delicate
+encrusting forms, which grew parasitically attached to shells
+and corals (<i>Hippothoa, Alecto</i>, &amp;c.); but perhaps the most
+characteristic forms belong to the genus <i>Ptilodictya</i> (figs.
+48 and 49). In this group the frond is flattened, with thin striated
+edges, sometimes sword-like or scimitar-shaped, but often more or
+less branched; and it consists of two layers of cells, separated
+by a delicate membrane, and opening upon opposite sides. Each of
+these little chambers or "cells" was originally tenanted by a
+minute animal, and the whole thus constituted a compound organism
+or colony.
+</p>
+
+<p class="indent">
+The Lamp-shells or <i>Brachiopods</i> are so numerous, and present
+such varied types, both in this and the succeeding period of
+the Upper Silurian, that the name of "Age of Brachiopods"
+<a name="page_109"><span class="page">Page 109</span></a>
+has with justice been applied to the Silurian period as a whole.
+It would be impossible here to enter into details as to the many
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 268px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig048.jpg" width="230" height="232" alt="Fig. 48" />
+<br />
+Fig. 48.&mdash;<i>Ptilodictya falciformis</i>. <i>a</i>,
+Small specimen of the natural size; <i>b</i>, Cross-section,
+showing the shape of the frond; <i>c</i>, Portion of the surface,
+enlarged. Trenton Limestone and Cincinnati Group, America.
+(Original.)
+</span>
+
+<span style="width: 271px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig049.jpg" width="276" height="227" alt="Fig. 49" />
+<br />
+Fig. 49.&mdash;A, <i>Ptilodictya acuta</i>; B. <i>Ptilodictya
+Schafferi</i>. <i>a</i>, Fragment, of the natural size; <i>b</i>,
+Portion, enlarged to show the cells. Cincinnati Group of Ohio
+and Canada. (Original.)
+</span>
+
+</span>
+
+different forms of Brachiopods which present themselves in the
+Lower Silurian deposits; but we may select the three genera
+<i>Orthis, Strophomena</i>, and <i>Leptœna</i> for
+illustration, as being specially characteristic of this period,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 603px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig050.jpg" width="595" height="337" alt="Fig. 50" />
+<br />
+Fig. 50.&mdash;Lower Silurian Brachiopods. <i>a</i>
+and <i>a'</i>, <i>Orthis biforata</i>, Llandeilo-Caradoc, Britain
+and America: <i>b, Orthis flabellulum</i>, Caradoc, Britain: <i>c,
+Orthis subquadrata</i>, Cincinnati Group, America; <i>c'</i>,
+Interior of the dorsal valve of the same: <i>d, Strophomena
+deltoidea</i>, Llandeilo-Caradoc, Britain and America. (After
+Meek, Hall, and Salter.)
+</span>
+</span>
+
+though not exclusively confined to it. The numerous shells which
+belong to the extensive and cosmopolitan genus <i>Orthis</i> (fig.
+50, <i>a, b, c,</i>
+<a name="page_110"><span class="page">Page 110</span></a>
+and fig. 51, <i>c</i> and <i>d</i>), are
+usually more or less transversely-oblong or subquadrate, the two
+valves (as more or less in all the Brachiopods) of unequal sizes,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 625px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig051.jpg" width="617" height="283" alt="Fig. 51" />
+<br />
+Fig. 51.&mdash;Lower Silurian Brachiopods, <i>a,
+Strophomena alternata</i>, Cincinnati Group, America; <i>b,
+Strophomena filitexta</i>, Trenton and Cincinnati Groups, America;
+<i>c, Orthis testudinaria</i>, Caradoc, Europe, and America;
+<i>d, d', Orthis plicateila</i>, Cincinnati Group, America; <i>e,
+e', e'', Leptœna sericea</i>, Llandeilo and Caradoc, Europe
+and America. (After Meek, Hall, and the Author.)
+</span>
+</span>
+
+generally more or less convex, and marked with radiating ribs or
+lines. The valves of the shell are united to one another by teeth
+and sockets, and there is a straight hinge-line. The beaks are
+also separated by a distinct space ("hinge-area"), formed in part
+by each valve, which is perforated by a triangular opening, through
+which, in the living condition, passed a muscular cord attaching
+the shell to some foreign object. The genus <i>Strophomena</i>
+(fig. 50, <i>d</i>, and 51, <i>a</i> and <i>b</i>) is very like
+<i>Orthis</i> in general character; but the shell is usually much
+flatter, one or other valve often being concave, the hinge-line is
+longer, and the aperture for the emission of the stalk of attachment
+is partially closed by a calcareous plate. In <i>Leptœna</i>,
+again (fig. 51, <i>e</i>), the shell is like <i>Strophomena</i>
+in many respects, but generally comparatively longer, often
+completely semicircular, and having one valve convex and the
+other valve concave. Amongst other genera of Brachiopods which are
+largely represented in the Lower Silurian rocks may be mentioned
+<i>Lingula, Crania, Discina, Trematis, Siphonotreta, Acrotreta,
+Rhynchonella</i>, and <i>Athyris</i>; but none of these can claim
+the importance to which the three previously-mentioned groups
+are entitled.
+</p>
+
+<p class="indent">
+The remaining Lower Silurian groups of <i>Mollusca</i> can be but
+briefly glanced at here. The Bivalves (<i>Lamellibranchiata</i>)
+find numerous representatives, belonging to such genera as
+<a name="page_111"><span class="page">Page 111</span></a>
+<i>Modiolopsis, Ctenodonta, Orthonota, Palœarca, Lyrodesma,
+
+<span style="float: right; margin: 4px; width: 115px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig052.jpg" width="107" height="273" alt="Fig. 52" />
+<br />
+Fig. 52.&mdash;<i>Murchisonia gracilis</i>, Trenton Limestone,
+America. (After Billings.)
+</span>
+
+Ambonychia</i>,and <i>Cleidophorus</i>. The Univalves
+(<i>Gasteropoda</i>) are also very numerous, the two most important
+genera being <i>Murchisonia</i> (fig. 52) and <i>Pleurotomaria</i>.
+In both these groups the outer lip of the shell is notched; but
+the shell in the former is elongated and turreted, whilst in
+the latter it is depressed. The curious oceanic Univalves known
+as the <i>Heteropods</i> are also very abundant, the principal
+forms belonging to <i>Bellerophon</i> and <i>Maclurea</i>. In the
+former (fig. 53) there is a symmetrical convoluted shell, like
+that of the Pearly Nautilus in shape, but without any internal
+partitions, and having the aperture often expanded and notched
+behind. The species of <i>Maclurea</i> (fig. 54) are found both
+in North America and in Scotland, and are exclusively confined
+to the Lower Silurian period, so far as known. They have the
+shell coiled into a flat spiral, the mouth being furnished with
+a very curious, thick, and solid lid or "operculum." The Lower
+Silurian <i>Pteropods</i>, or "Winged snails," are numerous,
+and belong principally to the genera <i>Theca, Conularia</i>,
+and <i>Tentaculites</i>, the last-mentioned of these often being
+extremely abundant in certain strata.
+</p>
+
+<p class="indent">
+Lastly, the Lower Silurian Rocks have yielded a vast number of
+chambered shells, referable to animals which belong to the same
+great division as the Cuttle-fishes (the <i>Cephalopoda</i>), and
+of which the Pearly Nautilus is the only living representative
+at the present day. In this group of <i>Cephalopods</i> the animal
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 368px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig053.jpg" width="360" height="184" alt="Fig. 53" />
+<br />
+Fig. 53.&mdash;Different views of <i>Bellerophon Argo</i>,
+Trenton Limestone, Canada. (After Billings.)
+</span>
+</span>
+
+possesses a well-developed external shell, which is divided into
+chambers by shelly partitions ("septa"). The animal lives in
+the last-formed and largest chamber of the shell, to which
+<a name="page_112"><span class="page">Page 112</span></a>
+it is organically connected by muscular attachments. The head is
+furnished with long muscular processes or "arms," and can be
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 556px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig054.jpg" width="548" height="196" alt="Fig. 54" />
+<br />
+Fig. 54.&mdash;Different views of <i>Maclurea crenulata</i>,
+Quebec Group, Newfoundland. (After Billings.)
+</span>
+</span>
+
+protruded from the mouth of the shell at will, or again withdrawn
+within it. We learn, also, from the Pearly Nautilus, that these
+animals must have possessed two pairs of breathing organs or
+"gills;" hence all these forms are grouped together under the
+name of the "Tetrabranchiate" Cephalopods (Gr. <i>tetra</i>,
+four; <i>bragchia</i>, gill). On the other hand, the ordinary
+Cuttle-fishes and Calamaries either possess an internal skeleton,
+or if they have an external shell, it is not chambered; their
+"arms" are furnished with powerful organs of adhesion in the form
+of suckers; and they possess only a single pair of gills. For
+this last reason they are termed the "Dibranchiate" Cephalopods
+(Gr. <i>dis</i>, twice; <i>bragchia</i>, gill). No trace of the
+true Cuttle-fishes has yet been found in Lower Silurian deposits;
+but the Tetrabranchiate group is represented by a great number
+of forms, sometimes of great size. The principal Lower Silurian
+genus is the well-known and widely-distributed <i>Orthoceras</i>
+(fig. 55). The shell in this genus agrees with that of the existing
+<i>Pearly Nautilus</i>, in consisting of numerous chambers separated
+by shelly partitions (or septa), the latter being perforated by
+a tube which runs the whole length of the shell after the last
+chamber, and is known as the "siphuncle" (fig. 56, <i>s</i>).
+The last chamber formed is the largest, and in it the animal
+lives. The chambers behind this are apparently filled with some
+gas secreted by the animal itself; and these are supposed to
+act as a kind of float, enabling the creature to move with ease
+under the weight of its shell. The various air-chambers, though
+the siphuncle passes through them, have no direct connection
+with one another; and it is believed that the animal has the
+power of slightly altering its specific gravity, and thus of
+rising or sinking in the water by driving additional fluid into
+the siphuncle or partially emptying it. The <i>Orthoceras</i>
+<a name="page_113"><span class="page">Page 113</span></a>
+further agrees with the Pearly Nautilus in the fact that
+the partitions or septa separating the different air-chambers are
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 268px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig055.jpg" width="227" height="448" alt="Fig. 55" />
+<br />
+Fig. 55.&mdash;Fragment of <i>Orthoceras crebriseptum</i>,
+Cincinnati Group, North America, of the natural size. The lower
+figure section showing the air-chambers, and the form and position
+of the siphuncle. (After Billings.)
+</span>
+
+<span style="width: 271px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig056.jpg" width="235" height="475" alt="Fig. 56" />
+<br />
+Fig. 56.&mdash;[14] Restoration of Orthoceras, the shell
+being supposed to be divided vertically, and only its upper part
+being shown. <i>a</i>, Arms; <i>f</i>, Muscular tube ("funnel")
+by which water is expelled from the mantle-chamber; <i>c</i>,
+Air-chambers; <i>s</i>, Siphuncle.
+</span>
+
+</span>
+
+simple and smooth, concave in front and convex behind, and devoid
+of the elaborate lobation which they exhibit in the Ammonites;
+whilst the siphuncle pierces the septa either in the centre or
+near it. In the Nautilus, however, the shell is coiled into a
+flat spiral; whereas in <i>Orthoceras</i> the shell is a straight,
+longer or shorter cone, tapering behind, and gradually expanding
+towards its mouth in front. The chief objections to the belief
+that the animal of the <i>Orthoceras</i> was essentially like
+that of the Pearly Nautilus are&mdash;the comparatively small size
+of the body-chamber, the often contracted aperture of the mouth,
+and the enormous size of some specimens of
+<a name="page_114"><span class="page">Page 114</span></a>
+the shell. Thus, some <i>Orthocerata</i> have been discovered
+measuring ten or twelve feet in length, with a diameter of a foot
+at the larger extremity. These colossal dimensions certainly make
+it difficult to imagine that the comparatively small body-chamber
+could have held an animal large enough to move a load so ponderous
+as its own shell. To some, this difficulty has appeared so great
+that they prefer to believe that the <i>Orthoceras</i> did not
+live in its shell at all, but that its shell was an internal
+skeleton similar to what we shall find to exist in many of the
+true Cuttle-fishes. There is something to be said in favour of
+this view, but it would compel us to believe in the existence in
+Lower Silurian times of Cuttle-fishes fully equal in size to the
+giant "Kraken" of fable. It need only be added in this connection
+that the Lower Silurian rocks have yielded the remains of many
+other Tetrabranchiate Cephalopods besides <i>Orthoceras</i>. Some
+of these belong to <i>Cyrtoceras</i>, which only differs from
+<i>Orthoceras</i> in the bow-shaped form of the shell; others
+belong to <i>Phragmoceras</i>, <i>Lituites</i>, &amp;c.; and,
+lastly; we have true <i>Nautili</i>, with their spiral shells,
+closely resembling the existing Pearly Nautilus.
+</p>
+
+<p class="footnote">
+[Footnote 14: This illustration is taken from a rough sketch
+made by the author many years ago, but he is unable to say from
+what original source it was copied.]
+</p>
+
+<p class="indent">
+Whilst all the sub-kingdoms of the Invertebrate animals are
+represented in the Lower Silurian rocks, no traces of Vertebrate
+animals have ever been discovered in these ancient deposits,
+unless the so-called "Conodonts" found by Pander in vast numbers
+in strata of this age [15] in Russia should prove to be really
+of this nature. These problematical bodies are of microscopic
+size, and have the form of minute, conical, tooth-shaped spines,
+with sharp edges, and hollow at the base. Their original discoverer
+regarded them as the horny teeth of fishes allied to the Lampreys;
+but Owen came to the conclusion that they probably belonged to
+Invertebrates. The recent investigation of a vast number of similar
+but slightly larger bodies, of very various forms, in the
+Carboniferous rocks of Ohio, has led Professor Newberry to the
+conclusion that these singular fossils really are, as Pander
+thought, the teeth of Cyclostomatous fishes. The whole of this
+difficult question has thus been reopened, and we may yet have
+to record the first advent of Vertebrate animals in the Lower
+Silurian.
+</p>
+
+<p class="footnote">
+[Footnote 15: According to Pander, the "Conodonts" are found not
+only in the Lower Silurian beds, but also in the "Ungulite Grit"
+(Upper Cambrian), as well as in the Devonian and Carboniferous
+deposits of Russia. Should the Conodonts prove to be truly the
+remains of fishes, we should thus have to transfer the first
+appearance of vertebrates to, at any rate, as early a period as
+the Upper Cambrian.]
+</p>
+
+<h3>
+<a name="page_115"><span class="page">Page 115</span></a>
+CHAPTER X.</h3>
+
+<p class="subtitle">
+THE UPPER SILURIAN PERIOD.
+</p>
+
+<p class="indent">
+Having now treated of the Lower Silurian period at considerable
+length, it will not be necessary to discuss the succeeding group of
+the <i>Upper Silurian</i> in the same detail&mdash;the more so, as
+with a general change of <i>species</i> the Upper Silurian animals
+belong for the most part to the same great types as those which
+distinguish the Lower Silurian. As compared, also, as regards
+the total bulk of strata concerned, the thickness of the Upper
+Silurian is generally very much below that of the Lower Silurian,
+indicating that they represent a proportionately shorter period of
+time. In considering the general succession of the Upper Silurian
+beds, we shall, as before, select Wales and America as being two
+regions where these deposits are typically developed.
+</p>
+
+<p class="indent">
+In Wales and its borders the general succession of the Upper
+Silurian rocks may be taken to be as follows, in ascending order
+(fig. 57):&mdash;
+</p>
+
+<p class="indent">
+(1) The base of the Upper Silurian series is constituted by a
+series of arenaceous beds, to which the name of "May Hill Sandstone"
+was applied by Sedgwick. These are succeeded by a series of
+greenish-grey or pale-grey slates ("Tarannon Shales"), sometimes
+of great thickness; and these two groups of beds together form
+what may be termed the "<i>May Hill Group</i>" (Upper Llandovery
+of Murchison). Though not very extensively developed in Britain,
+this zone is one very well marked by its fossils; and it corresponds
+with the "Clinton Group" of North America, in which similar fossils
+occur. In South Wales this group is clearly unconformable to the
+highest member of the subjacent Lower Silurian (the Llandovery
+group); and there is reason to believe that a similar, though
+less conspicuous, physical break occurs very generally between
+the base of the Upper and the summit of the Lower Silurian.
+</p>
+
+<p class="indent">
+(2) The <i>Wenlock Group</i> succeeds the May Hill group, and
+constitutes the middle member of the Upper Silurian. At its base
+it may have an irregular limestone ("Woolhope Limestone"), and
+its summit may be formed by a similar but thicker calcareous
+deposit ("Wenlock Limestone"); but the bulk of the group is made
+up of the argillaceous and shaly strata known as the "Wenlock
+Shale." In North Wales the Wenlock group is, represented by a
+great accumulation of flaggy and gritty strata (the "Denbighshire
+Flags and Grits"), and similar beds (the
+<a name="page_116"><span class="page">Page 116</span></a>
+"Coniston Flags" and "Coniston Grits") take the same place in
+the north of England.
+</p>
+
+<p class="indent">
+(3) The <i>Ludlow Group</i> is the highest member of the Upper
+Silurian, and consists typically of a lower arenaceous and shaly
+series (the "Lower Ludlow Rock") a middle calcareous member (the
+"Aymestry Limestone"), and an upper shaly and sandy series (the
+"Upper Ludlow Rock" and "Downton Sandstone"). At the summit, or
+close to the summit, of the Upper Ludlow, is a singular stratum
+only a few inches thick (varying from an inch to a foot), which
+contains numerous remains of crustaceans and fishes, and is well
+known under the name of the "bone-bed." Finally, the Upper Ludlow
+rock graduates invariably into a series of red sandy deposits,
+which, when of a flaggy character, are known locally as the
+"Tile-stones." These beds are probably to be regarded as the
+highest member of the Upper Silurian; but they are sometimes
+looked upon as passage-beds into the Old Red Sandstone, or as
+the base of this formation. It is, in fact, apparently impossible
+to draw any actual line of demarcation between the Upper Silurian
+and the overlying deposits of the Devonian or Old Red Sandstone
+series. Both in Britain and in America the Lower Devonian beds
+repose with perfect conformity upon the highest Silurian beds, and
+the two formations appear to pass into one another by a gradual
+and imperceptible transition.
+</p>
+
+<p class="indent">
+The Upper Silurian strata of Britain vary from perhaps 3000 or
+4000 feet in thickness up to 8000 or 10,000 feet. In North America
+the corresponding series, though also variable, is generally of
+much smaller thickness, and may be under 1000 feet. The general
+succession of the Upper Silurian deposits of North America is
+as follows:&mdash;
+</p>
+
+<p class="indent">
+(1) <i>Medina Sandstone</i>.&mdash;This constitutes the base of the
+Upper Silurian, and consists of sandy strata, singularly devoid
+of life, and passing below in some localities into a conglomerate
+("Oneida Conglomerate"), which is stated to contain pebbles derived
+from the older beds, and which would thus indicate an unconformity
+between the Upper and Lower Silurian.
+</p>
+
+<p class="indent">
+(2) <i>Clinton Group</i>.&mdash;Above the Medina sandstone are beds
+of sandstone and shale, sometimes with calcareous bands, which
+constitute what is known as the "Clinton Group." The Medina and
+Clinton groups are undoubtedly the equivalent of the "May Hill
+Group" of Britain, as shown by the identity of their fossils.
+</p>
+
+<p class="indent">
+<span style="width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<a name="page_117"><span class="page">Page 117</span></a>
+GENERALIZED SECTION OF THE UPPER SILURIAN STRATA OF WALES AND
+SHROPSHIRE.
+<br />
+Fig. 57.
+<br />
+<img src="images/fig057.jpg" width="546" height="505" alt="Fig. 57" />
+</span>
+</span>
+
+(3) <i>Niagara Group</i>.&mdash;This group consists typically of a
+series of argillaceous beds ("Niagara Shale") capped by limestones
+("Niagara Limestone"); and the name of the group is derived from
+the fact that it is over limestones of this age that the Niagara
+river is precipitated to form the great Falls. In places the
+Niagara group is wholly calcareous, and it is continued upwards
+into a series of marls and sandstones, with beds of salt and masses
+of gypsum (the "Salina Group"), or into a series of magnesian
+limestones ("Guelph Limestones"). The Niagara group, as a whole,
+corresponds unequivocally with the Wenlock group of Britain.
+</p>
+
+<p class="indent">
+(4) <i>Lower Helderberg Group</i>.&mdash;The Upper Silurian period
+in North America was terminated by the deposition of a series of
+calcareous beds, which derive the name of "Lower Helderberg" from
+the Helderberg mountains, south of Albany, and
+<a name="page_118"><span class="page">Page 118</span></a>
+which are divided into several zones, capable of recognition
+by their fossils, and known by local names (Tentaculite Limestone,
+Water-lime, Lower Pentamerus Limestone, Delthyris Shaly Limestone,
+and Upper Pentamerus Limestone). As a whole, this series may be
+regarded as the equivalent of the Ludlow group of Britain, though
+it is difficult to establish any precise parallelism. The summit
+of the Lower Heiderberg group is constituted by a coarse-grained
+sandstone (the "Oriskany Sandstone"), replete with organic
+remains, which have to a large extent a Silurian <i>facies</i>.
+Opinions differ as to whether this sandstone is to be regarded
+as the highest bed of the Upper Silurian or the base of the
+Devonian. We thus see that in America, as in Britain, no other
+line than an artificial one can be drawn between the Upper
+Silurian and the overlying Devonian.
+</p>
+
+<p class="indent">
+As regards the <i>life</i> of the Upper Silurian period, we have,
+as before, a number of so-called "Fucoids," the true vegetable
+nature of which is in many instances beyond doubt. In addition
+to these, however, we meet for the first time, in deposits of
+this age, with the remains of genuine land-plants, though our
+knowledge of these is still too scanty to enable us to construct
+any detailed picture of the terrestrial vegetation of the period.
+Some of these remains indicate the existence of the remarkable
+genus <i>Lepidodendron</i>&mdash;a genus which played a part of
+great importance in the forests of the Devonian and Carboniferous
+periods, and which may be regarded as a gigantic and extinct type of
+the Club-mosses (<i>Lycopodiaceœ</i>). Near the summit of the
+Ludlow formation in Britain there have also been found beds charged
+with numerous small globular bodies, which Dr Hooker has shown
+to be the seed-vessels or "sporangia" of Club-mosses. Principal
+Dawson further states that he has seen in the same formation
+fragments of wood with the structure of the singular Devonian
+Conifer known as <i>Prototaxites</i>. Lastly, the same distinguished
+observer has described from the Upper Silurian of North America
+the remains of the singular land-plants belonging to the genus
+<i>Psilophyton</i>, which will be referred to at greater length
+hereafter.
+</p>
+
+<p class="indent">
+The marine life of the Upper Silurian is in the main constituted by
+types of animals similar to those characterising the Lower Silurian,
+though for the most part belonging to different species. The
+<i>Protozoans</i> are represented principally by <i>Stromatopora</i>
+and <i>Ischadites</i>, along with a number of undoubted sponges
+(such as <i>Amphispongia, Astrœospongia, Astylospongia</i>,
+and <i>Palœomanon</i>).
+</p>
+
+<p class="indent">
+Amongst the <i>Cœlenterates</i>, we find the old group of
+<i>Graptolites</i> now verging on extinction. Individuals still
+<a name="page_119"><span class="page">Page 119</span></a>
+remain numerous, but the variety of generic
+and specific types has now become greatly reduced. All the
+branching and complex forms of the Arenig, the twin-Graptolites
+
+<span style="float: right; margin: 4px; width: 199px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig058.jpg" width="191" height="424" alt="Fig. 1" />
+<br />
+Fig. 58.&mdash;A, <i>Monograptus priodon</i>, slightly enlarged.
+B, Fragment of the same viewed from behind. C, Fragment of the
+same viewed in front, showing the mouths of the cellules. D,
+Cross-section of the same. From the Wenlock Group (Coniston
+Flags of the North of England). (Original.)
+</span>
+
+and <i>Dicranograpti</i> of the Llandeilo, and the double-celled
+<i>Diplograpti</i> and <i>Climacograpti</i> of the Bala group,
+have now disappeared. In their place we have the singular
+<i>Retiolites</i>, with its curiously-reticulated skeleton; and
+several species of the single-celled genus <i>Monograptus</i>,
+of which a characteristic species (<i>M. Priodon</i>) is here
+figured. If we remove from this group the plant-like
+<i>Dictyonemœ</i>, which are still present, and which
+survive into the Devonian, no known species of <i>Graptolite</i>
+has hitherto been detected in strata higher in geological position
+than the Ludlow. This, therefore, presents us with the first
+instance we have as yet met with of the total disappearance and
+extinction of a great and important series of organic forms.
+</p>
+
+<p class="indent">
+The <i>Corals</i> are very numerously represented in the Upper
+Silurian rocks some of the limestones (such as the Wenlock Limestone)
+being often largely composed of the skeletons of these animals.
+Almost all the known forms of this period belong to the two great
+divisions of the Rugose and Tabulate corals, the former being
+represented by species of <i>Zaphrentis, Omphyma, Cystiphyllum,
+Strombodes, Acervularia, Cyathophyllum</i>, &amp;c.; whilst the latter
+belong principally to the genera <i>Favosites, Chœtetes,
+Halysites, Syringopora, Heliolites</i>, and <i>Plasmopora</i>.
+Amongst the <i>Rugosa</i>, the first appearance of the great and
+important genus <i>Cyathophyllum</i>, so characteristic of the
+Palæozoic period, is to be noted; and amongst the
+<i>Tabulata</i> we have similarly the first appearance, in force
+at any rate, of the widely-spread genus <i>Favosites</i>&mdash;the
+"Honeycomb-corals." The "Chain-corals" (<i>Halysites</i>), figured
+below (fig. 59), are also very common examples of the Tabulate
+corals during this period, though they occur likewise in the Lower
+Silurian.
+</p>
+
+<p class="indent">
+<a name="page_120"><span class="page">Page 120</span></a>
+Amongst the <i>Echinodermata</i>, all those orders which have hard
+parts capable of ready preservation are more or less largely
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 508px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig059.jpg" width="500" height="383" alt="Fig. 59" />
+<br />
+Fig. 59.&mdash;<i>a, Halysites catenularia</i>, small variety, of
+the natural size; <i>b,</i> Fragment of a large variety of the
+same, of the natural size; <i>c</i>, Fragment of limestone with
+the tubes of <i>Halysites agglomerata</i>, of the natural size;
+<i>d,</i> Vertical section of two tubes of the same, showing the
+tabulæ, enlarged. Niagara Limestone (Wenlock), Canada.
+(Original.)
+</span>
+</span>
+
+represented. We have no trace of the Holothurians or Sea-cucumbers;
+but this is not surprising, as the record of the past is throughout
+almost silent as to the former existence of these soft-bodied
+creatures, the scattered plates and spicules in their skin offering
+a very uncertain chance of preservation in the fossil condition.
+The Sea-urchins (<i>Echinoids</i>) are said to be represented by
+examples of the old genus <i>Palœchinus</i>. The Star-fishes
+(<i>Asteroids</i>) and the Brittle-stars (<i>Ophiuroids</i>) are,
+comparatively speaking, largely represented; the former by species
+of <i>Palasterina</i> (fig. 60), <i>Palœaster</i> (fig. 60),
+<i>Palœocoma</i> (fig. 60), <i>Petraster, Glyptaster</i>, and
+<i>Lepidaster</i>&mdash;and the latter by species of <i>Protaster</i>
+(fig. 61), <i>Palœodiscus, Acroura</i>, and <i>Eucladia</i>.
+The singular <i>Cystideans</i>, or "Globe Crinoids," with their
+globular or ovate, tesselated bodies (fig. 46, A, C, D,), are also
+not uncommon in the Upper Silurian; and if they do not become finally
+extinct here, they certainly survive the close of this period by
+but a very brief time. By far the most important, however, of the
+Upper Silurian Echinodenns, are the Sea-lilies or <i>Crinoids</i>.
+The limestones of this period are often largely composed of the
+fragmentary columns and detached
+<a name="page_121"><span class="page">Page 121</span></a>
+plates of these creatures, and some
+of them (such as the Wenlock Limestone of Dudley) have yielded
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 513px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig060.jpg" width="505" height="173" alt="Fig. 60" />
+<br />
+Fig. 60.&mdash;Upper Silurian Star-fishes. 1, <i>Palasterina
+primœva</i>, Lower Ludlow; 2, <i>Paloeaster Ruthveni</i>,
+Lower Ludlow; 3, <i>Palœocoma Colvini</i>, Lower Ludlow.
+(After Salter.)
+</span>
+</span>
+
+perhaps the most exquisitely-preserved examples of this group
+with which we are as yet acquainted. However varied in their
+forms, these beautiful organisms consist of a globular, ovate, or
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 534px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig061.jpg" width="526" height="316" alt="Fig. 61" />
+<br />
+Fig. 61.&mdash;A, <i>Protaster Sedgwickii</i>, showing the disc and
+bases of the arms; B, Portion of an arm, greatly enlarged.
+Lower Ludlow. (After Salter.)
+</span>
+</span>
+
+pear-shaped body (the "calyx"), supported upon a longer or shorter
+jointed stem (or "column"). The body is covered externally with
+an armour of closely-fitting calcareous plates (fig. 62), and
+its upper surface is protected by similar but smaller plates
+more loosely connected by a leathery integument. From the upper
+surface of the body, round its margin, springs a series of longer
+or shorter flexible processes, composed of innumerable calcareous
+joints or pieces, movably united with one
+<a name="page_122"><span class="page">Page 122</span></a>
+another. The arms are
+typically five in number; but they generally subdivide at least
+once, sometimes twice, and they are furnished with similar but
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 533px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig062.jpg" width="525" height="352" alt="Fig. 62" />
+<br />
+Fig. 62.&mdash;Upper Silurian Crinoids. <i>a</i>, Calyx and arms
+of <i>Eucalyptocrinus polydactylus</i>, Wenlock Limestone; <i>b,
+Ichthyocrinus lœvis</i>, Niagara Limestone, America; <i>c,
+Taxocrinus tuberculatus</i>, Wenlock Limestone. (After M'Coy
+and Hall.)
+</span>
+</span>
+
+more slender lateral branches or "pinnules," thus giving rise
+to a crown of delicate feathery plumes. The "column" is the stem
+by which the animal is attached permanently to the bottom of the
+sea; and it is composed of numerous separate plates, so jointed
+together that whilst the amount of movement between any two pieces
+must be very limited, the entire column acquires more or less
+flexibility, allowing the organism as a whole to wave backwards
+and forwards on its stalk. Into the exquisite <i>minutiœ</i>
+of structure by which the innumerable parts entering into the
+composition of a single Crinoid are adapted for their proper
+purposes in the economy of the animal, it is impossible to enter
+here. No period, as before said, has yielded examples of greater
+beauty than the Upper Silurian, the principal genera represented
+being <i>Cyathocrinus, Platycrinus, Marsupiocrinus, Taxocrinus,
+Eucalyptocrinus, Ichthyocrinus, Mariacrinus, Periechocrinus,
+Glyptocrinus, Crotalocrinus</i>, and <i>Edriocrinus</i>.
+</p>
+
+<p class="indent">
+The tracks and burrows of <i>Annelides</i> are as abundant in
+the Upper Silurian strata as in older deposits, and have just
+as commonly been regarded as plants. The most abundant forms
+are the cylindrical, twisted bodies (Planolites), which are
+<a name="page_123"><span class="page">Page 123</span></a>
+so frequently found on the surfaces of sandy
+beds, and which have been described as the stems of sea-weeds.
+These fossils (fig. 63), however, can be nothing more, in most
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 531px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig063.jpg" width="523" height="421" alt="Fig. 63" />
+<br />
+Fig. 63.&mdash;<i>Planolites vulgaris</i>, the filled-up burrows
+of a marine worm. Upper Silurian (Clinton Group), Canada.
+(Original.)
+</span>
+</span>
+
+cases, than the filled-up
+burrows of marine worms resembling the living Lob-worms. There
+are also various remains which belong to the group of the
+tube-inhabiting Annelides (<i>Tubicola</i>). Of this nature are
+the tubes of <i>Serpulites</i> and <i>Cornultites</i>, and the
+little spiral discs of <i>Spirorbis Lewisii</i>.
+</p>
+
+<p class="indent">
+Amongst the <i>Articulates</i>, we still meet only with the remains
+of <i>Crustaceans</i>. Besides the little bivalved
+<i>Ostracoda</i>&mdash;which here are occasionally found of the size
+of beans&mdash;and various <i>Phyllopods</i> of different kinds, we
+have an abundance of <i>Trilobites</i>. These last-mentioned ancient
+types, however, are now beginning to show signs of decadence; and
+though still individually numerous, there is a great diminution
+in the number of generic types. Many of the old genera, which
+flourished so abundantly in Lower Silurian seas, have now died out;
+and the group is represented chiefly by species of <i>Cheirurus,
+Encrinurus, Harpes, Proetus, Lichas, Acidaspis, Illœnus,
+Calymene, Homalonotus</i>, and <i>Phacops</i>&mdash;the last of
+these, one of the
+<a name="page_124"><span class="page">Page 124</span></a>
+highest and most beautiful of the groups of Trilobites, attaining
+here its maximum of development. In the annexed illustration
+(fig. 64) some of the characteristic Upper Silurian Trilobites are
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 518px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig064.jpg" width="510" height="383" alt="Fig. 64" />
+<br />
+Fig. 64.&mdash;Upper Silurian Trilobites. <i>a, Cheirurus
+bimucronatus</i>, Wenlock and Caradoc; <i>b, Phacops
+longicaudatus</i>, Wenlock, Britain, and America; <i>c, Phacops
+Downingiœ</i>, Wenlock and Ludlow; <i>d, Harpes ungula</i>,
+Upper Silurian, Bohemia. (After Salter and Barrande.)
+</span>
+</span>
+
+represented&mdash;all, however, belonging to genera which have their
+commencement in the Lower Silurian period. In addition to the above,
+the Ludlow rocks of Britain and the Lower Helderberg beds of North
+America have yielded the remains of certain singular Crustaceans
+belonging to the extinct order of the <i>Eurypterida</i>. Some
+of these wonderful forms are not remarkable for their size; but
+others, such as <i>Pterygotus Anglicus</i> (fig. 65), attain a
+length of six feet or more, and may fairly be considered as the
+giants of their class. The Eurypterids are most nearly allied
+to the existing King-crabs (<i>Limuli</i>), and have the anterior
+end of the body covered with a great head-shield, carrying two
+pairs of eyes, the one simple and the other compound. The feelers
+are converted into pincers, whilst the last pair of limbs have
+their bases covered with spiny teeth so as to act as jaws, and
+are flattened and widened out towards their extremities so as
+to officiate as swimming-paddles. The hinder extremity of the
+body is composed of thirteen rings, which have no legs attached
+to them; and the last segment of the tail is either a flattened
+plate or a
+<a name="page_125"><span class="page">Page 125</span></a>
+narrow, sword-shaped spine. Fragments of the skeleton
+are easily recognised by the peculiar scale-like markings with
+
+<span style="float: right; margin: 4px; width: 254px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig065.jpg" width="235" height="442" alt="Fig. 65" />
+<br />
+Fig. 65.&mdash;<i>Pterygotus Anglicus</i>, viewed
+from the under side, reduced in size, and restored. <i>c c</i>,
+The feelers (antennæ), terminating in nipping-claws; <i>o
+o</i>, Eyes; <i>m m</i>, Three pairs of jointed limbs, with
+pointed extremities; <i>n n</i>, Swimming-paddles, the bases of
+which are spiny and act as jaws. Upper Silurian, Lanarkshire.
+(After Henry Woodward.)
+</span>
+
+which the surface is adorned, and which look not at all unlike
+the scales of a fish. The most famous locality for these great
+Crustaceans is Lesmahagow, in Lanarkshire, where many different
+species have been found. The true King-crabs (<i>Limuli</i>) of
+existing seas also appear to have been represented by at least
+one form (<i>Neolimulus</i>) in the Upper Silurian.
+</p>
+
+<p class="indent">
+Coming to the <i>Mollusca</i>, we note the occurrence of the same
+great groups as in the Lower Silurian. Amongst the Sea-mosses
+(<i>Polyzoa</i>), we have the ancient Lace-corals (<i>Fenestella</i>
+and <i>Retepora</i>), with the nearly-allied <i>Glauconome</i>,
+and species of <i>Ptilodictya</i> (fig. 66); whilst many forms
+often referred here may probably have to be transferred to the
+Corals, just as some so-called Corals will ultimately be removed
+to the present group.
+</p>
+
+<p class="indent">
+The Brachiopods continued to flourish during the Upper Silurian
+Period in immense numbers and under a greatly increased variety
+of forms. The three prominent Lower Silurian genera <i>Orthis,
+Strophomena</i>, and <i>Leptœna</i> are still well represented,
+though they have lost their former preeminence. Amongst the numerous
+types which have now come upon the scene for the first time, or
+which have now a special development, are <i>Spirifera</i> and
+<i>Pentamerus</i>. In the first of these (fig. 69. <i>b, c</i>),
+one of the valves of the shell (the dorsal) is furnished in its
+interior with a pair of great calcareous spires, which served
+for the support of the long and fringed fleshy processes or "arms"
+which were attached to the sides of the mouth.[16] In the genus
+<i>Pentamerus</i> (fig. 70) the
+<a name="page_126"><span class="page">Page 126</span></a>
+shell is curiously subdivided in its
+interior by calcareous plates. The <i>Pentameri</i> commenced their
+existence at the very close of the Lower Silurian (Llandovery), and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 475px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig066.jpg" width="467" height="220" alt="Fig. 66" />
+<br />
+Fig. 66.&mdash;Upper Silurian Polyzoa. <i>1</i>, Fan-shaped
+frond of <i>Rhinopora verrucosa</i>; 1<i>a</i>, Portion of the
+surface of the same, enlarged; 2 and 2<i>a</i>, <i>Phœnopora
+ensiformis</i>, of the natural size and enlarged; 3 and 3<i>a</i>,
+<i>Helopora fragilis</i>, of the natural size and enlarged; 4
+and 4<i>a</i>, <i>Ptilodictya raripora</i>, of the natural size
+and enlarged. The specimens are all from the Clinton Formation
+(May Hill Group) of Canada. (Original.)
+</span>
+</span>
+
+survived to the close of the Upper Silurian; but they are specially
+characteristic of the May Hill and Wenlock groups, both in Britain
+and in other regions. One species, <i>Pentamerus galeatus</i>, is
+common to Sweden, Britain, and America. Amongst the remaining Upper
+Silurian Brachiopods are the extraordinary
+<a name="page_127"><span class="page">Page 127</span></a>
+<i>Trimerellids</i>; the old and at the same time modern
+<i>Lingulœ, Discinœ</i>, and <i>Craniœ</i>;
+together with many species of <i>Atrypa</i> (fig. 68, <i>e</i>),
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 523px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig068.jpg" width="515" height="225" alt="Fig. 68" />
+<br />
+Fig. 68.&mdash;Upper
+Silurian Brachiopods. <i>a a'</i>, <i>Leptocœlia
+plano-convexa</i>, Clinton Group, America; <i>b b'</i>,
+<i>Rhynchonella neglecta</i>, Clinton Group, America; <i>c,
+Rhynchonella cuneata</i>, Niagara Group, America, and Wenlock
+Group, Britain; <i>d d', Orthis elelgantula</i>, Llandeilo to
+Ludlow, America and Europe; <i>e e', Atrypa hemispherica</i>,
+Clinton Group, America, and Llandovery and May Hill Groups,
+Britain; <i>f f', Atrypa congesta</i>, Clinton Group, America;
+<i>g g', Orthis Davidsoni</i>, Clinton Group, America. (After
+Hall, Billings, and the Author.)
+</span>
+</span>
+
+<i>Leptocœlia</i> (fig. 68, <i>a</i>),
+<i>Rhynchonella</i> (fig. 68, <i>b, c</i>), <i>Meristella</i>
+(fig. 69, <i>a, e, f</i>), <i>Athyris, Retzia, Chonetes</i>,
+&amp;c.
+</p>
+
+<p class="footnote">
+[Footnote 16: In all the Lamp-shells the mouth is provided with
+two long fleshy organs, which carry delicate filaments on their
+sides, and which are usually coiled into a spiral. These organs
+are known as the "arms," and it is from their presence that the
+name of "<i>Brachiopoda</i>" is derived (Gr. <i>brachion</i>, arm;
+<i>podes</i>, feet). In some cases the arms are merely coiled away
+within the shell, without any support; but in other cases they are
+carried upon a more or less elaborate shelly loop, often spoken
+of as the "carriage-spring apparatus." In the <i>Spirifers</i>,
+and in other ancient genera, this apparatus is coiled up into a
+complicated spiral (fig. 67). It is these "arms," with or without
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 518px; text-align: center;">
+<img src="images/fig067.jpg" width="510" height="161" alt="Fig. 67" />
+<br />
+Fig. 67.&mdash;<i>Spirifera hysterica</i>. The right-hand figure
+shows the interior of the dorsal valve with the calcareous
+spires for the support of the arms.
+</span>
+</span>
+
+the supporting loops or spires, which serve as one of the special
+characters distinguishing the <i>Brachiopods</i> from the true
+Bivalves (<i>Lamellibranchiata</i>).]
+</p>
+
+<div class="center">
+<table border="0" width="519">
+<tr><td class="center">
+<img src="images/fig069.jpg" width="515" height="358" alt="Fig. 69" />
+</td></tr>
+<tr><td class="left"><span class="image">
+Fig. 69.&mdash;<i>a a', Meristella intermedia</i>, Niagara Group, America;
+<i>b, Spirifera Niagarensis</i>, Niagara Group, America; <i>c c',
+Spirifera crispa</i>, May Hill to Ludlow, Britain, and Niagara
+Group, America; <i>d, Strophomena (Streptorhynchus) subplana</i>,
+Niagara Group, America; <i>e, Meristella naviformis</i>, Niagara
+Group, America; <i>f, Meristella cylindrica</i>, Niagara Group,
+America. (After Hall, Billings, and the Author.)
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+The higher groups of the <i>Mollusca</i> are also largely represented
+in the Upper Silurian. Apart from some singular types,
+<a name="page_128"><span class="page">Page 128</span></a>
+such as the
+huge and thick-shelled <i>Megalomi</i> of the American Wenlock
+formation, the Bivalves (<i>Lamellibranchiata</i>) present little of
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 539px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig070.jpg" width="531" height="199" alt="Fig. 70" />
+<br />
+Fig. 70.&mdash;<i>Pentamerus Knightii</i>. Wenlock and Ludlow. The
+right-hand figure shows the internal partitions of the shell.
+</span>
+</span>
+
+special interest; for though sufficiently numerous, they are rarely
+well preserved, and their true affinities are often uncertain.
+Amongst the most characteristic genera of this period may be
+mentioned <i>Cardiola</i> (fig. 71, A and C) and <i>Pterinea</i>
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 529px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig071.jpg" width="521" height="176" alt="Fig. 71" />
+<br />
+Fig. 71.&mdash;Upper Silurian Bivalves. A, <i>Cardiola
+interrupta</i>, Wenlock and Ludlow; B, <i>Pterinea subfalcata</i>,
+Wenlock; C, <i>Cardiola fibrosa</i>, Ludlow. (After Salter and
+M'Coy.)
+</span>
+</span>
+
+(fig. 71, B), though the latter survives to a much later date.
+The Univalves (<i>Gasteropoda</i>) are very numerous, and a
+few characteristic forms are here figured (fig. 72). Of these,
+no genus is perhaps more characteristic than <i>Euomphalus</i>
+(fig. 72, <i>b</i>), with its flat discoidal shell, coiled up
+into an oblique spiral, and deeply hollowed out on one side;
+but examples of this group are both of older and of more modern
+date. Another very extensive genus, especially in America, is
+Platyceras (fig. 72, <i>a</i> and <i>f</i>), with its thin fragile
+shell&mdash;often hardly coiled up at all&mdash;its minute spire,
+and its widely-expanded, often sinuated mouth. The British
+<i>Acroculiœ</i> should probably be placed here, and the
+group has with reason been regarded as allied to the Violet-snails
+(<i>Ianthina</i>) of the open Atlantic. The
+<a name="page_129"><span class="page">Page 129</span></a>
+species of <i>Platyostoma</i> (fig. 72, <i>h</i>) also belong
+to the same family; and the entire group is continued throughout
+the Devonian into the Carboniferous. Amongst other well-known
+Upper Silurian Gasteropods are species of the genera <i>Holopea</i>
+(fig. 72, <i>g</i>), <i>Holopella</i> (fig. 72. <i>e</i>),
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 541px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig072.jpg" width="533" height="339" alt="Fig. 72" />
+<br />
+Fig. 72.&mdash;Upper Silurian Gasteropods. <i>a, Platyceras
+ventricosum</i>, Lower Helderberg, America; <i>b, Euomphalus
+discors</i>, Wenlock, Britain; <i>c, Holopella obsoleta</i> Ludlow,
+Britain; <i>d, Platyschisma helicites</i>, Upper Ludlow, Britain;
+<i>e, Holopella gracilior</i>, Wenlock, Britain; <i>f, Platyceras
+multisinuatum</i>, Lower Helderberg, America; <i>g, Holopea
+subconica</i>, Lower Helderberg, America; <i>h, h', Platyostoma
+Niagarense</i>, Niagara Group, America. (After Hall, M'Coy, and
+Salter.)
+</span>
+</span>
+
+<i>Platyschisma</i> (fig. 72, <i>d</i>), <i>Cyclonema,
+Pleurotomaria, Murchisonia, Trochonema</i>, &amp;c. The oceanic
+
+<span style="float: right; margin: 4px; width: 59px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig073.jpg" width="51" height="207" alt="Fig. 73" />
+<br />
+Fig. 73.&mdash;<i>Tentaculites ornatus</i>. Upper Silurian of Europe
+and North America.
+</span>
+
+Univalves (<i>Heteropods</i>) are represented mainly by species of
+<i>Bellerophon</i>; and the Winged Snails, or <i>Pteropods</i>, can
+still boast of the gigantic <i>Thecœ</i> and
+<i>Conulariœ</i>, which characterise yet older deposits. The
+commonest genus of <i>Pteropoda</i>, however, is <i>Tentaculites</i>
+(fig. 73), which clearly belongs here, though it has commonly been
+regarded as the tube of an Annelide. The shell in this group
+is a conical tube, usually adorned with prominent transverse
+rings, and often with finer transverse or longitudinal striæ
+as well; and many beds of the Upper Silurian exhibit myriads of
+such tubes scattered promiscuously over their surfaces.
+</p>
+
+<p class="indent">
+<a name="page_130"><span class="page">Page 130</span></a>
+The last and highest group of the <i>Mollusca</i>&mdash;that
+of the <i>Cephalopoda</i>&mdash;is still represented only by
+<i>Tetrabranchiate</i> forms; but the abundance and variety of
+these is almost beyond belief. Many hundreds of different species
+are known, chiefly belonging to the straight <i>Orthoceratites</i>,
+but the slightly-curved <i>Cyrtoceras</i> is only little less
+common. There are also numerous forms of the genera <i>Phragmoceras,
+Ascoceras, Gyroteras, Lituites</i>, and <i>Nautilus</i>. Here, also,
+are the first-known species of the genus <i>Goniatites</i>&mdash;a
+group which attains considerable importance in later deposits, and
+which is to be regarded as the precursor of the <i>Ammonites</i> of
+the Secondary period.
+</p>
+
+<p class="indent">
+Finally, we find ourselves for the first time called upon to
+consider the remains of undoubted vertebrate animals, in the
+
+<span style="float: left; margin: 4px; width: 164px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig074.jpg" width="156" height="197" alt="Fig. 74" />
+<br />
+Fig. 74.&mdash;Head-shield of <i>Pteraspis Banksii</i>, Ludlow
+rocks. (After Murchison.)
+</span>
+
+form of <i>Fishes</i>. The oldest of these remains, so far as
+yet known, are found in the Lower Ludlow rocks, and they consist
+of the bony head-shields or bucklers of certain singular armoured
+fishes belonging to the group of the <i>Ganoids</i>, represented at
+the present day by the Sturgeons, the Gar-pikes of North America,
+and a few other less familiar forms. The principal Upper Silurian
+genus of these is <i>Pteraspis</i>, and the annexed illustration
+(fig. 74) will give some idea of the extraordinary form of the
+shield covering the head in these ancient fishes. The remarkable
+stratum near the top of the Ludlow formation known as the "bone-bed"
+has also yielded the remains of shark-like fishes. Some of these,
+for which the name of <i>Onchus</i> has been proposed, are in
+the form of compressed, slightly-curved spines (fig. 75, A),
+which would appear to be of the nature of the strong defensive
+spines implanted in front of certain of the fins in many living
+fishes. Besides these, have been found fragments of prickly skin
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 462px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig075.jpg" width="454" height="66" alt="Fig. 75" />
+<br />
+Fig. 75.&mdash;A, Spine of <i>Onchus tenuistriatus</i>; B,
+Shagreen-scales of <i>Thelodus</i>. Both from the "bone-bed"
+of the Upper Ludlow rocks. (After Murchison.)
+</span>
+</span>
+
+or shagreen (<i>Sphagodus</i>), along with minute cushion-shaped
+bodies (<i>Thelodus</i>, fig. 75, B), which
+<a name="page_131"><span class="page">Page 131</span></a>
+are doubtless the bony scales of some fish resembling the modern
+Dog-fishes. As the above mentioned remains belong to two distinct,
+and at the same time highly-organised, groups of the fishes, it
+is hardly likely that we are really presented here with the first
+examples of this great class. On the contrary, whether the
+so-called "Conodonts" should prove to be the teeth of fishes or
+not, we are justified in expecting that unequivocal remains of
+this group of animals will still be found in the Lower Silurian.
+It is interesting, also, to note that the first appearance of
+fishes&mdash;the lowest class of vertebrate animals&mdash;so far
+as known to us at present, does not take place until after all
+the great sub-kingdoms of invertebrates have been long in
+existence; and there is no reason for thinking that future
+discoveries will materially affect the <i>relative</i> order of
+succession thus indicated.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+From the vast and daily-increasing mass of Silurian literature, it
+is impossible to do more than select a small number of works which
+have a classical and historical interest to the English-speaking
+geologist, or which embody researches on special groups of Silurian
+animals&mdash;anything like an enumeration of all the works and
+papers on this subject being wholly out of the question. Apart,
+therefore, from numerous and in many cases extremely important
+memoirs, by various well-known observers, both at home and abroad,
+the following are some of the more weighty works to which the
+student may refer in investigating the physical characters and
+succession of the Silurian strata and their fossil contents:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Siluria.' Sir Roderick Murchison.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Geology of Russia in Europe.' Murchison (with M. de Verneuil
+  and Count von Keyserling).</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Bassin Silurien de Bohême Centrale.' Barrande.</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>'Introduction to the Catalogue of British Palæozoic
+  Fossils in the Woodwardian Museum of Cambridge.'
+  Sedgwick.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>'Die Urwelt Russlands.' Eichwald.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>'Report on the Geology of Londonderry, Tyrone,' &amp;c.
+  Portlock.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>"Geology of North Wales"&mdash;'Mem. Geol. Survey of Great
+  Britain,' vol. iii. Ramsay.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>'Geology of Canada,' 1863. Sir W. E. Logan; and the
+  'Reports of Progress of the Geological Survey' since
+  1863.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>'Memoirs of the Geological Survey of Great
+  Britain.'</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Reports of the Geological Surveys of the States of New
+  York, Illinois, Ohio, Iowa, Michigan, Vermont, Wisconsin,
+  Minnesota,' &amp;c. By Emmons, Hall, Worthen, Meek, Newberry,
+  Orton, Winchell, Dale Owen, &amp;c.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'Thesaurus Siluricus.' Bigsby.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>'British Palæozoic Fossils.' M'Coy.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>'Synopsis of the Silurian Fossils of Ireland,'
+  M'Coy.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>"Appendix to the Geology of North Wales"&mdash;'Mem. Geol.
+  Survey,' vol. iii. Salter.</td></tr>
+<tr><td class="right" valign="top">
+<a name="page_132"><span class="page">Page 132</span></a>
+  (15)</td>
+ <td>'Catalogue of the Cambrian and Silurian Fossils in the
+  Woodwardian Museum of Cambridge.' Salter.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Characteristic British Fossils.' Baily.</td></tr>
+<tr><td class="right" valign="top">(17)</td>
+ <td>'Catalogue of British Fossils.' Morris.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>'Palæozoic Fossils of Canada.' Billings.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>'Decades of the Geological Survey of Canada.' Billings,
+  Salter, Rupert Jones.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>'Decades of the Geological Survey of Great Britain.' Salter,
+  Edward, Forbes.</td></tr>
+<tr><td class="right" valign="top">(21)</td>
+ <td>'Palæontology of New York,' vols. i.-iii.
+  Hall.</td></tr>
+<tr><td class="right" valign="top">(22)</td>
+ <td>'Palæontology of Illinois.' Meek and
+  Worthen.</td></tr>
+<tr><td class="right" valign="top">(23)</td>
+ <td>'Palæontology of Ohio.' Meek, Hall, Whitfield,
+  Nicholson.</td></tr>
+<tr><td class="right" valign="top">(24)</td>
+ <td>'Silurian Fauna of West Tennessee' (Silurische Fauna des
+  Westlichen Tennessee). Ferdinand Rœmer.</td></tr>
+<tr><td class="right" valign="top">(25)</td>
+ <td>'Reports on the State Cabinet of New York.'
+  Hall.</td></tr>
+<tr><td class="right" valign="top">(26)</td>
+ <td>'Lethæa Geognostica.' Bronn.</td></tr>
+<tr><td class="right" valign="top">(27)</td>
+ <td>'Index Palæontologicus.' Bronn.</td></tr>
+<tr><td class="right" valign="top">(28)</td>
+ <td>'Lethæa Rossica.' Eichwald.</td></tr>
+<tr><td class="right" valign="top">(29)</td>
+ <td>'Lethæa Suecica.' Hisinger.</td></tr>
+<tr><td class="right" valign="top">(30)</td>
+ <td>'Palæontologica Suecica.' Angelin.</td></tr>
+<tr><td class="right" valign="top">(31)</td>
+ <td>'Petrefacta Germaniæ.' Goldfuss.</td></tr>
+<tr><td class="right" valign="top">(32)</td>
+ <td>'Versteinerungen der Grauwacken-Formation in Sachsen.'
+  Geinitz.</td></tr>
+<tr><td class="right" valign="top">(33)</td>
+ <td>'Organisation of Trilobites' (Ray Society).
+  Burmeister.</td></tr>
+<tr><td class="right" valign="top">(34)</td>
+ <td>'Monograph of the British Trilobites'
+  (Palæontographical Society). Salter.</td></tr>
+<tr><td class="right" valign="top">(35)</td>
+ <td>'Monograph of the British Merostomata'
+  (Palæontographical Society). Henry Woodward.</td></tr>
+<tr><td class="right" valign="top">(36)</td>
+ <td>'Monograph of British Brachiopoda' (Palæontographical
+  Society). Thomas Davidson.</td></tr>
+<tr><td class="right" valign="top">(37)</td>
+ <td>'Graptolites of the Quebec Group.' James Hall.</td></tr>
+<tr><td class="right" valign="top">(38)</td>
+ <td>'Monograph of the British Graptolitidæ.'
+  Nicholson.</td></tr>
+<tr><td class="right" valign="top">(39)</td>
+ <td>'Monographs on the Trilobites. Pteropods, Cephalopods,
+  Graptolites,' &amp;c. Extracted from the 'Système Silurien
+  du Centre de la Bohême.' Barrande.</td></tr>
+<tr><td class="right" valign="top">(40)</td>
+ <td>'Polypiers Fossiles des Terrains Paleozoiques,' and 'Monograph
+  of the British Corals' (Palæontographical Society). Milne
+  Edwards and Jules Haime.</td></tr>
+</table>
+
+<h3>CHAPTER XI.</h3>
+
+<p class="subtitle">
+THE DEVONIAN AND OLD RED SANDSTONE PERIOD.
+</p>
+
+<p class="indent">
+Between the summit of the Ludlow formation and the strata which
+are universally admitted to belong to the Carboniferous series
+<a name="page_133"><span class="page">Page 133</span></a>
+is a great system of deposits, to which the
+name of "Old Red Sandstone" was originally applied, to distinguish
+them from certain arenaceous strata which lie above the coal ("New
+Red Sandstone"). The Old Red Sandstone, properly so called, was
+originally described and investigated as occurring in Scotland
+and in South Wales and its borders; and similar strata occur in
+the south of Ireland. Subsequently it was discovered that sediments
+of a different mineral nature, and containing different organic
+remains, intervened between the Silurian and the Carboniferous
+rocks on the continent of Europe, and strata with similar
+palæontological characters to these were found occupying
+a considerable area in Devonshire. The name of "Devonian" was
+applied to these deposits; and this title, by common usage, has
+come to be regarded as synonymous with the name of "Old Red
+Sandstone." Lastly, a magnificent series of deposits, containing
+marine fossils, and undoubtedly equivalent to the true "Devonian"
+of Devonshire, Rhenish Prussia, Belgium, and France, is found to
+intervene in North America between the summit of the Silurian
+and the base of the Carboniferous rocks.
+</p>
+
+<p class="indent">
+Much difficulty has been felt in correlating the true "Devonian
+Rocks" with the typical "Old Red Sandstone"&mdash;this difficulty
+arising from the fact that though both formations are fossiliferous,
+the peculiar fossils of each have only been rarely and partially
+found associated together. The characteristic crustaceans and many
+of the characteristic fishes of the Old Red are wanting in the
+Devonian; whilst the corals and marine shells of the latter do
+not occur in the former. It is impossible here to enter into any
+discussion as to the merits of the controversy to which this
+difficulty has given origin. No one, however, can doubt the
+importance and reality of the Devonian series as an independent
+system of rocks to be intercalated in point of time between the
+Silurian and the Carboniferous. The want of agreement, both
+lithologically and palæontologically, between the Devonian
+and the Old Red, can be explained by supposing that these two
+formations, though wholly or in great part <i>contemporaneous</i>,
+and therefore strict equivalents, represent deposits in two
+different geographical areas, laid down under different conditions.
+On this view, the typical Devonian rocks of Europe, Britain, and
+North America are the deep-sea deposits of the Devonian period,
+or, at any rate, are genuine marine sediments formed far from
+land. On the other hand, the "Old Red Sandstone" of Britain and
+the corresponding "Gaspé Group" of Eastern
+<a name="page_134"><span class="page">Page 134</span></a>
+Canada represent the shallow-water shore-deposits
+of the same period. In fact, the former of these last-mentioned
+deposits contains no fossils which can be asserted positively
+to be <i>marine</i> (unless the Eurypterids be considered so);
+and it is even conceivable that it represents the sediments of
+an inland sea. Accepting this explanation in the meanwhile, we
+may very briefly consider the general succession of the deposits
+of this period in Scotland, in Devonshire, and in North America.
+</p>
+
+<p class="indent">
+In Scotland the "Old Red" forms a great series of arenaceous and
+conglomeratic strata, attaining a thickness of many thousands
+of feet, and divisible into three groups. Of these, the <i>Lower
+Old Red Sandstone</i> reposes with perfect conformity upon the
+highest beds of the Upper Silurian, the two formations being almost
+inseparably united by an intermediate series of "passage-beds."
+In mineral nature this group consists principally of massive
+conglomerates, sandstones, shales, and concretionary limestones;
+and its fossils consist chiefly of large crustaceans belonging
+to the family of the <i>Eurypterids</i>, fishes, and plants. The
+<i>Middle Old Red Sandstone</i> consists of flagstones, bituminous
+shales, and conglomerates, sometimes with irregular calcareous
+bands; and its fossils are principally fishes and plants. It
+may be wholly wanting, when the <i>Upper Old Red</i> seems to
+repose unconformably upon the lower division of the series. The
+<i>Upper Old Red Sandstone</i> consists of conglomerates and
+grits, along with a great series of red and yellow
+sandstones&mdash;the fossils, as before, being fishes and remains
+of plants. The Upper Old Red graduates upwards conformably into
+the Carboniferous series.
+</p>
+
+<p class="indent">
+The Devonian rocks of Devonshire are likewise divisible into
+a lower, middle, and upper division. The <i>Lower Devonian</i>
+or <i>Lynton Group</i> consists of red and purple sandstones,
+with marine fossils, corresponding to the "Spirifer Sandstein" of
+Germany, and to the arenaceous deposits (Schoharie and Cauda-Galli
+Grits) at the base of the American Devonian. The <i>Middle
+Devonian</i> or <i>Ilfracombe Group</i> consists of sandstones
+and flags, with calcareous slates and crystalline limestones,
+containing many corals. It corresponds with the great "Eifel
+Limestone" of the Continent, and, in a general way, with the
+Corniferous Limestone and Hamilton group of North America. The
+<i>Upper Devonian</i> or <i>Pilton Group</i>, lastly, consists
+of sandstones and calcareous shales which correspond with the
+"Clymenia Limestone" and "Cypridina Shales" of the Continent,
+and with the Chemung and Portage groups of
+<a name="page_135"><span class="page">Page 135</span></a>
+North America. It seems quite possible, also, that the
+so-called "Carboniferous Slates" of Ireland correspond with
+this group, and that the former would be more properly regarded
+as forming the summit of the Devonian than the base of the
+Carboniferous.
+</p>
+
+<p class="indent">
+In no country in the world, probably, is there a finer or more
+complete exposition of the strata intervening between the Silurian
+and Carboniferous deposits than in the United States. The following
+are the main subdivisions of the Devonian rocks in the State of
+New York, where the series may be regarded as being typically
+developed (fig. 67):&mdash;
+</p>
+
+<p class="indent">
+(1) <i>Cauda-Galli Grit</i> and <i>Schoharie
+Grit</i>.&mdash;Considering
+the "Oriskany Sandstone" as the summit of the Upper Silurian, the
+base of the Devonian is constituted by the arenaceous deposits
+known by the above names, which rest quite conformably upon the
+Silurian, and which represent the Lower Devonian of Devonshire.
+The <i>Cauda-Galli Grit</i> is so called from the abundance of
+a peculiar spiral fossil (<i>Spirophyton cauda-Galli</i>), which
+is of common occurrence in the Carboniferous rocks of Britain,
+and is supposed to be the remains of a sea-weed.
+</p>
+
+<p class="indent">
+(2) The <i>Corniferous</i> or <i>Upper Helderberg
+Limestone</i>.&mdash;A
+series of limestones usually charged with considerable quantities
+of siliceous matter in the shape of hornstone or chert (Lat.
+<i>cornu</i>, horn). The thickness of this group rarely exceeds
+300 feet; but it is replete with fossils, more especially with the
+remains of corals. The Corniferous Limestone is the equivalent of
+the coral-bearing limestones of the Middle Devonian of Devonshire
+and the great "Eifel Limestone" of Germany.
+</p>
+
+<p class="indent">
+(3) The <i>Hamilton Group</i>&mdash;consisting of shales at the
+base ("Marcellus shales"); flags, shales, and impure limestones
+("Hamilton beds") in the middle; and again a series of shales
+("Genesee Slates") at the top. The thickness of this group varies
+from 200 to 1200 feet, and it is richly charged with marine
+fossils.
+</p>
+
+<p class="indent">
+(4) The <i>Portage Group</i>.&mdash;A great series of shales,
+flags, and shaly sandstones, with few fossils.
+</p>
+
+<p class="indent">
+(5) The <i>Chemung Group</i>.&mdash;Another great series of
+sandstones and shales, but with many fossils. The Portage and
+Chemung groups may be regarded as corresponding with the Upper
+Devonian of Devonshire. The Chemung beds are succeeded by a
+great series of red sandstones and shales&mdash;the
+<a name="page_136"><span class="page">Page 136</span></a>
+"Catskill Group"&mdash;which pass conformably
+upwards into the Carboniferous, and which may perhaps be
+regarded as the equivalent of the great sandstones of the Upper
+Old Red in Scotland.
+</p>
+
+<p class="indent">
+Throughout the entire series of Devonian deposits in North America
+no unconformability or physical break of any kind has hitherto been
+detected; nor is there any marked interruption to the current of
+life, though each subdivision of the series has its own fossils.
+No completely natural line can thus be indicated, dividing the
+Devonian in this region from the Silurian on the one hand, and the
+Carboniferous on the other hand. At the same time, there is the
+most ample evidence, both stratigraphical and palæontological,
+as to the complete independence of the American Devonian series
+as a distinct life-system between the older Silurian and the
+later Carboniferous. The subjoined section (fig. 76) shows
+diagrammatically the general succession of the Devonian rocks
+of North America.
+</p>
+
+<p class="indent">
+As regards the <i>life</i> of the Devonian period, we are now
+acquainted with a large and abundant terrestrial
+<i>flora</i>&mdash;this being the first time that we have met
+with a land vegetation capable of reconstruction in any
+fulness. By the researches of Gœppert, Unger, Dawson,
+Carruthers, and other botanists, a knowledge has been acquired
+of a large number of Devonian plants, only a few of which can
+be noticed here. As might have been anticipated, the greater
+number of the vegetable remains of this period have been
+obtained from such shallow-water deposits as the Old Red
+Sandstone proper and the Gaspè series of North America, and
+few traces of plant-life occur in the strictly marine sediments.
+Apart from numerous remains, mostly of a problematical nature,
+referred to the comprehensive group of the Sea-weeds, a large
+number of Ferns have now been recognised, some being, of the
+ordinary plant-like type (<i>Pecopteris, Neuropteris, Alethopteris,
+Sphenopteris</i>, &amp;c.), whilst others belong to the gigantic
+group of the "Tree-ferns" (<i>Psaronius, Caulopteris</i>, &amp;c.)
+Besides these there is an abundant development of the singular extinct
+types of the <i>Lepidodendroids</i>, the <i>Sigillarioids</i>,
+and the <i>Calamites</i>, all of which attained their maximum in the
+Carboniferous. Of these, the <i>Lepidodendra</i> may be regarded as
+gigantic, tree-like Club-mosses (<i>Lycopodiaceœ</i>); the
+<i>Calamites</i> are equally gigantic Horse-tails
+(<i>Equisetaceœ</i>); and the <i>Sigillarioids</i>, equally
+huge in size, in some respects hold a position intermediate between
+the Club-mosses and the Pines (Conifers). The Devonian rocks have
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 500px;
+  font-size: smaller; text-align: center;">
+<a name="page_137"><span class="page">Page 137</span></a>
+GENERALIZED SECTION OF THE DEVONIAN ROCKS OF NORTH AMERICA.
+<br />
+Fig. 76.
+<br />
+<img src="images/fig076.jpg" width="482" height="544" alt="Fig. 76" />
+</span>
+</span>
+
+also yielded traces of many other plants (such as <i>Annularia,
+Asterophyllites, Cardiocarpon</i>, &amp;c.), which acquire a
+greater pre-dominance in the Carboniferous period, and which
+will be spoken of in discussing the structure of the plants of the
+Coal-measures. Upon the whole, the one plant which may be considered
+as specially characteristic of the Devonian (though not confined
+to this series) is the <i>Psilophyton</i> (fig. 77) of Dr Dawson.
+These singular plants have slender branching stems, with sparse
+needle-shaped leaves, the young stems being at first coiled up,
+crosier-fashion, like the young fronds of ferns, whilst the old
+branches carry numerous spore-cases. The
+<a name="page_138"><span class="page">Page 138</span></a>
+stems and branches seem
+to have attained a height of two or three feet; and they sprang
+from prostrate "root-stocks" or creeping stems. Upon the whole,
+
+<span style="float: left; margin: 4px; width: 228px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig077.jpg" width="220" height="638" alt="Fig. 77" />
+<br />
+Fig. 77.&mdash;Restoration of <i>Psilophyton princeps</i>. Devonian,
+Canada. (After Dawson.)
+</span>
+
+Principal Dawson is disposed to regard <i>Psilophyton</i> as
+a "generalised type" of plants intermediate between the Ferns and
+the Club-mosses. Lastly, the Devonian deposits have yielded the
+remains of the first actual <i>trees</i> with which we are as yet
+acquainted. About the nature of some of these (<i>Ormoxylon</i>
+and <i>Dadoxylon</i>) no doubt can be entertained, since their
+trunks not only show the concentric rings of growth characteristic
+of exogenous trees in general, but their woody tissue exhibits
+under the microscope the "discs" which are characteristic of
+the wood of the Pines and Firs (see fig. 2). The singular genus
+<i>Prototaxites</i>, however, which occurs in an older portion
+of the Devonian series than the above, is not in an absolutely
+unchallenged position. By Principal Dawson it is regarded as the
+trunk of an ancient <i>Conifer</i>&mdash;the most ancient known;
+but Mr Carruthers regards it as more probably the stem of a
+gigantic sea-weed. The trunks of <i>Prototaxites</i> (fig. 78, A)
+vary from one to three feet in diameter, and exhibit concentric
+rings of growth; but its woody fibres have not hitherto been
+clearly demonstrated to possess discs. Before leaving the Devonian
+vegetation, it may be mentioned that the hornstone or chert so
+abundant in the Corniferous limestone of North America has been
+shown to contain the remains of various microscopic plants
+(<i>Diatoms</i> and <i>Desmids</i>). We find also in the same
+siliceous material the singular spherical bodies, with radiating
+spines, which occur so abundantly in the chalk flints, and which
+are termed <i>Xanthidia</i>. These may be regarded
+<a name="page_139"><span class="page">Page 139</span></a>
+as probably the spore-cases of the minute plants known as
+<i>Desmidiœ</i>.
+</p>
+
+<div class="center">
+<table border="0" width="563">
+<tr><td>
+<img src="images/fig078.jpg" width="559" height="416" alt="Fig. 78" />
+</td></tr>
+<tr><td class="left"><span class="image">Fig. 78.&mdash;A, Trunk
+of <i>Prototaxites Logani</i>, eighteen inches in diameter, as seen
+in the cliff near L'Anse Brehaut, Gaspé; B, Two wood-cells
+showing spiral fibres and obscure pores, highly magnified. Lower
+Devonian, Canada. (After Dawson)
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+The Devonian <i>Protozoans</i> have still to be fully investigated.
+True Sponges (such as <i>Astrtœospongia, Sphœrospongia</i>,
+&amp;c.) are not unknown; but by far the commonest representatives of
+this sub-kingdom in the Devonian strata are <i>Stromatopora</i> and its
+allies. These singular organisms (fig. 79) are not only very abundant
+in some of the Devonian limestones&mdash;both in the Old World and
+the New&mdash;but they often attain very large dimensions. However
+much they may differ in minor details, the general structure of
+these bodies is that of numerous, concentrically-arranged, thin,
+calcareous laminæ, separated by narrow interspaces, which in
+turn are crossed by numerous delicate vertical pillars, giving the
+whole mass a cellular structure, and dividing it into innumerable
+minute quadrangular compartments. Many of the Devonian
+<i>Stromatoporœ</i> also exhibit on their surface the rounded
+openings of canals, which can hardly have served any other purpose
+than that of permitting the sea-water to gain ready access to every
+part of the organism.
+</p>
+
+<p class="indent">
+No true <i>Graptolites</i> have ever been detected in strata of
+<a name="page_140"><span class="page">Page 140</span></a>
+of Devonian age; and the whole of this group has become
+extinguished&mdash;unless we refer here the still surviving
+<i>Dictyonemœ</i>. The <i>Cœlenterates</i>, however,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 411px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig079.jpg" width="403" height="439" alt="Fig. 79" />
+<br />
+Fig. 79.&mdash;<i>a</i>,
+Part of the under surface of <i>Stromatopora tuberculata</i>,
+showing the wrinkled basement membrane and the openings of
+water-canals, of the natural size; <i>b</i>, Portion of the
+upper surface of the same, enlarged; <i>c</i>, Vertical section
+of a fragment, magnified to show the internal structure.
+Corniferous Limestone, Canada. (Original.)
+</span>
+</span>
+
+are represented by a vast number of <i>Corals</i>, of beautiful
+forms and very varied types. The marbles of Devonshire, the
+Devonian limestones of the Eifel and of France, and the calcareous
+strata of the Corniferous and Hamilton groups of America, are
+often replete with the skeletons of these organisms&mdash;so much so
+as to sometimes entitle the rock to be considered as representing an
+ancient coral-reef. In some instances the Corals have preserved
+their primitive calcareous composition; and if they are embedded
+in soft shales, they may weather out of the rock in almost all
+their original perfection. In other cases, as in the marbles of
+Devonshire, the matrix is so compact and crystalline that the
+included corals can only be satisfactorily studied by means of
+polished sections. In other cases, again, the corals have been
+more or less completely converted into flint, as in the Corniferous
+limestone of North America. When this is the case, they often come,
+by the action of the weather, to stand out from
+<a name="page_141"><span class="page">Page 141</span></a>
+the enclosing
+rock in the boldest relief, exhibiting to the observer the most
+minute details of their organization. As before, the principal
+
+<span style="float: left; width: 100%;
+ text-align: center; font-size: smaller;">
+
+<span style="width: 312px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig080.jpg" width="304" height="690" alt="Fig. 80" />
+<br />
+Fig. 80.&mdash;<i>Cystiphyllum vesiculosum</i>, showing a
+succession of cups produces by budding from the original coral.
+Of the natural size. Devonian, America and Europe. (Original.)
+</span>
+
+<span style="width: 281px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig081.jpg" width="273" height="508" alt="Fig. 81" />
+<br />
+Fig. 81&mdash;<i>Zaphrentis cornicula</i>, of the natural size.
+Devonian, America. (Original.)
+<br />
+<img src="images/fig082.jpg" width="260" height="135" alt="Fig. 82" />
+<br />
+Fig. 82&mdash;<i>Heliophyllum exiguum</i>, viewed from in front and
+behind. Of the natural size. Devonian, Canada. (Original.)
+</span>
+
+</span>
+
+representatives of the Corals are still referable to the groups of
+the <i>Rugosa</i> and <i>Tabulata</i>. Amongst the Rugose group
+we find a vast number of simple "cup-corals," generally known by
+the quarrymen as "horns," from their shape. Of
+<a name="page_142"><span class="page">Page 142</span></a>
+the many forms of these, the species of <i>Cyathophyllum,
+Heliophyllum</i> (fig. 82), <i>Zaphrentis</i> (fig. 81), and
+<i>Cystiphyllum</i> (fig. 80), are perhaps those most abundantly
+represented&mdash;none of these genera, however, except
+<i>Heliophyllum</i>, being peculiar to the Devonian period. There
+are also numerous compound Rugose corals, such as species of
+<i>Eridophyllum, Diphyphyllum, Syringopora,
+Phillipsastrœa</i>, and some of the forms of
+<i>Cyathophyllum</i> and <i>Crepidophyllum</i> (fig. 83). Some
+of these compound corals attain a very large size, and form of
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 383px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig083.jpg" width="375" height="329" alt="Fig. 83" />
+<br />
+Fig. 83.&mdash;Portion of a mass of <i>Crepidophyllum Archiaci</i>,
+of the natural size. Hamilton Formation, Canada. (After
+Billings.)
+</span>
+</span>
+
+themselves regular beds, which have an analogy, at any rate, with
+existing coral-reefs, though there are grounds for believing that
+these ancient types differed from the modern reef-builders in
+being inhabitants of deep water. The "Tabulate Corals" are hardly
+less abundant in the Devonian rocks than the <i>Rugosa</i>; and
+being invariably compound, they hardly yield to the latter in the
+dimensions of the aggregations which they sometimes form.
+</p>
+
+<p class="indent">
+The commonest, and at the same time the largest, of these are
+the "honeycomb corals," forming the genus <i>Favosites</i> (figs.
+84, 85), which derive both their vernacular and their technical
+names from their great likeness to masses of petrified honeycomb.
+The most abundant species are <i>Favosites Gothlandica</i> and
+<i>F. Hemispherica</i>, both here figured, which form masses
+sometimes not less than two or three feet in diameter. Whilst
+<i>Favosites</i> has acquired a popular name by its honey-combed
+appearance, the resemblance of <i>Michelinia</i> to a fossilised
+<a name="page_143"><span class="page">Page 143</span></a>
+wasp's nest with the comb exposed is hardly less striking, and
+has earned for it a similar recognition from the non-scientific
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 286px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig084.jpg" width="278" height="235" alt="Fig. 84" />
+<br />
+Fig. 84.&mdash;Portion of a mass of <i>Favosites Gothlandica</i>,
+of the natural size. Upper Silurian and Devonian of Europe
+and America. (Original.) Billings.
+</span>
+
+<span style="width: 291px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig085.jpg" width="283" height="232" alt="Fig. 85" />
+<br />
+Fig. 85.&mdash;Fragment of <i>Favosites hemispherica</i>, of
+the natural size. Upper Silurian and Devonian of America.
+(After Billings.)
+</span>
+
+</span>
+
+public. In addition to these, there are numerous branching or
+plant-like Tabulate Corals, often of the most graceful form,
+which are distinctive of the Devonian in all parts of the world.
+</p>
+
+<p class="indent">
+The <i>Echinoderms</i> of the Devonian period call for little
+special notice. Many of the Devonian limestones are "crinoidal;"
+and the <i>Crinoids</i> are the most abundant and widely-distributed
+representatives of their class in the deposits of this period.
+</p>
+
+<p class="indent">
+The <i>Cystideans</i>, with doubtful exceptions, have not been
+recognised in the Devonian; and their place is taken by the allied
+group of the "Pentremites," which will be further spoken of as
+occurring in the Carboniferous rocks. On the other hand, the
+Star-fishes, Brittle-stars, and Sea-urchins are all continued
+by types more or less closely allied to those of the preceding
+Upper Silurian.
+</p>
+
+<p class="indent">
+Of the remains of Ringed-worms (<i>Annelides</i>), the most numerous
+and the most interesting are the calcareous envelopes of some
+small tube-inhabiting species. No one who has visited the seaside
+can have failed to notice the little spiral tubes of the existing
+<i>Spirorbis</i> growing attached to shells, or covering the fronds
+of the commoner Sea weeds (especially <i>Fucus serratus</i>).
+These tubes are inhabited by a small Annelide, and structures of
+a similar character occur not uncommonly from the Upper Silurian
+upwards. In the Devonian rocks, <i>Spirorbis</i> is an extremely
+common fossil, growing in hundreds attached to the outer surface
+of corals and shells, and appearing
+<a name="page_144"><span class="page">Page 144</span></a>
+in many specific forms (figs. 86 and 87); but almost all the known
+
+<!-- Note: The book incorrectly numbered the next two plates as
+     Fig. 87 and Fig. 88. As a result there is no Fig. 86, but
+     there are two Fig. 88 illustrations. -->
+
+<span style="float: left; margin: 4px; width: 314px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig086.jpg" width="301" height="125" alt="Fig. 86" />
+<br />
+Fig. 87.&mdash;<i>a, Spirobois omphalodes</i>, natural size and
+enlarged. Devonian, Europe and America; <i>b, Spirorbis
+Arkonensis</i>, of the natural size and enlarged; <i>c</i>, The
+same, with the tube twisted in the reverse direction. Devonian,
+America. (Original.)
+<br />
+<img src="images/fig087.jpg" width="306" height="102" alt="Fig. 87" />
+Fig. 88.&mdash;<i>a b, Spirorbis laxus</i>, enlarged, Upper
+Silurian, America; <i>c, Spirorbis spinulifera</i>, of the
+natural size and enlarged, Devonian, Canada. (After Hall and
+the Author.)
+</span>
+
+examples are of small size, and are liable to escape a cursory
+examination.
+</p>
+
+<p class="indent">
+The <i>Crustaceans</i> of the Devonian are principally
+<i>Eurypterids</i> and <i>Trilobites</i>. Some of the former
+attain gigantic dimensions, and the quarrymen in the Scotch Old
+Red give them the name of "seraphim" from their singular scale-like
+ornamentation. The <i>Trilobites</i>, though still sufficiently
+abundant in some localites, have undergone a yet further diminution
+since the close of the Upper Silurian. In both America and Europe
+quite a number of generic types have survived from the Silurian,
+but few or no new ones make their appearance during this period
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 528px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig088.jpg" width="520" height="317" alt="Fig. 88" />
+<br />
+Fig. 88.&mdash;Devonian Trilobites; <i>a, Phacops latifrons</i>,
+Devonian of Britain, the Continent of Europe, and South America;
+<i>b, Homalonotus armatus</i>, Europe; <i>c, Phacops
+(Trimerocephalus) lœvis</i>, Europe; <i>d</i>, Head-shield
+of <i>Phacops (Portlockia) granulatus</i>, Europe. (After Salter
+and Burmeister.)
+</span>
+</span>
+
+in either the Old World or the New. The <i>species</i>, however,
+are distinct; and the
+<a name="page_145"><span class="page">Page 145</span></a>
+principal forms belong to the genera
+<i>Phacops</i> (fig. 88, <i>a, c, d</i>), <i>Homalonotus</i>
+(fig. 88, <i>b</i>), <i>Proetus</i>, and <i>Bronteus</i>. The
+species figured above under the name of <i>Phacops latifrons</i>
+(fig. 88, <i>a</i>), has an almost world-wide distribution, being
+found in the Devonian of Britain, Belgium, France, Germany, Russia,
+Spain, and South America; whilst its place is taken in North
+America by the closely-allied <i>Phacops rana</i>. In addition
+to the <i>Trilobites</i>, the Devonian deposits have yielded
+the remains of a number of the minute <i>Ostracoda</i>, such as
+<i>Entomis</i> ("<i>Cypridina</i>"), <i>Leperditia</i>, &amp;c.,
+which sometimes occur in vast numbers, as in the so-called
+"<i>Cypridina</i> Slates" of the German Devonian. There are also
+a few forms of <i>Phyllopods</i> (<i>Estheria</i>). Taken as
+a whole, the Crustacean fauna of the Devonian period presents
+many alliances with that of the Upper Silurian, but has only
+slight relationships with that of the Lower Carboniferous.
+</p>
+
+<p class="indent">
+Besides <i>Crustaceans</i>, we meet here for the first time with
+the remains of <i>air-breathing Articulates</i>, in the shape of
+<i>Insects</i>. So far, these have only been obtained from the
+Devonian rocks of North America, and they indicate the existence
+of at least four generic types, all more or less allied to the
+existing May-flies (<i>Ephemeridœ</i>). One of these
+interesting primitive insects, namely, <i>Platephemera antiqua</i>
+(fig. 89), appears to have measured five inches in expanse of wing;
+
+<span style="float: left; margin: 4px; width: 273px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig089.jpg" width="265" height="173" alt="Fig. 89" />
+<br />
+Fig. 89.&mdash;Wing of <i>Platephemera antiqua</i> Devonian,
+America. (After Dawson.)
+</span>
+
+and another (<i>Xelloneura antiquorum</i>) has attached to its wing
+the remains of a "stridulating-organ" similar to that possessed
+by the modern Grasshoppers&mdash;the instrument, as Principal
+Dawson remarks, of "the first music of living things that Geology
+as yet reveals to us."
+</p>
+
+<p class="indent">
+Amongst the <i>Mollusca</i>, the Devonian rocks have yielded a
+great number of the remains of Sea-mosses (<i>Polyzoa</i>). Some
+of these belong to the ancient type <i>Ptilodictya</i>, which
+seems to disappear here, or to the allied <i>Clathropora</i>
+(fig. 90), with its fenestrated and reticulated fronds. We meet
+also with the graceful and delicate stems of <i>Ceriopora</i>
+(fig. 91).
+</p>
+
+<p class="indent">
+The majority of the Devonian <i>Polyzoa</i> belong, however,
+to the great and important Palæozoic group of the Lace-corals
+(<i>Fenestella</i>, figs. 92 and 94, <i>Retepora</i>, fig. 93,
+<i>Polypora</i>, and their allies). In all these forms there is
+a horny skeleton, of a
+<a name="page_146"><span class="page">Page 146</span></a>
+fan-like or funnel-shaped form, which grew
+attached by its base to some foreign body. The frond consists
+of slightly-diverging or nearly parallel branches, which are
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 368px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig090.jpg" width="360" height="199" alt="Fig. 90" />
+<br />
+Fig. 90.&mdash;Fragment of <i>Clathropora intertexta</i>, of the
+natural size and enlarged. Devonian, Canada. (Original.)
+</span>
+
+<span style="width: 162px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig091.jpg" width="158" height="171" alt="Fig. 91" />
+<br />
+Fig. 91.&mdash;Fragment of <i>Ceriopora Hamiltonensis</i>, of the
+natural size and enlarged. Devonian, Canada. (Original.)
+</span>
+
+</span>
+
+either united by delicate cross-bars, or which bend alternately
+from side to side, and become directly united with one another
+at short intervals&mdash;in either case giving origin to numerous
+oval or oblong perforations, which communicate to the whole
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 299px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig092.jpg" width="291" height="268" alt="Fig. 92" />
+<br />
+Fig. 92.&mdash;Fragment of <i>Fenestella magnifica</i>, of the
+natural size and enlarged. Devonian, Canada. (Original.)
+</span>
+
+<span style="width: 242px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig093.jpg" width="234" height="122" alt="Fig. 93" />
+<br />
+Fig. 93.&mdash;Fragment of <i>Retepora Phillipsi</i>, of the
+natural size and enlarged. Devonian, Canada. (Original.)
+<br />
+<img src="images/fig094.jpg" width="232" height="158" alt="Fig. 94" />
+<br />
+Fig. 94.&mdash;Fragment of <i>Fenestella cribrosa</i>, of the
+natural size and enlarged. Dovonian, Canada. (Original.)
+</span>
+
+</span>
+
+plant-like colony a characteristic netted and lace-like appearance.
+On one of its surfaces&mdash;sometimes the internal, sometimes the
+external&mdash;the frond carries a number of minute chambers or
+<a name="page_147"><span class="page">Page 147</span></a>
+"cells," which are generally borne in rows on the branches, and of
+which each originally contained a minute animal.
+</p>
+
+<p class="indent">
+The <i>Brachiopods</i> still continue to be represented in great
+force through all the Devonian deposits, though not occurring in
+the true Old Red Sandstone. Besides such old types as <i>Orthis,
+Strophomena, Lingula, Athyris</i>, and <i>Rhynchonella</i>, we find
+some entirely new ones; whilst various types which only commenced
+their existence in the Upper Silurian, now undergo a great expansion
+and development. This last is especially the case with the two
+families of the <i>Spiriferidœ</i> and the
+<i>Produclidœ</i>. The <i>Spirifers</i>, in particular, are
+especially characteristic of the Devonian, both in the Old and New
+Worlds&mdash;some of the most typical forms, such as <i>Spirifera
+mucronata</i> (fig. 96), having the shell "winged," or with the
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 161px; vertical-align:top; text-align: justify;
+  margin: 4px;">
+<img src="images/fig095.jpg" width="153" height="92" alt="Fig. 95" />
+<br />
+Fig. 95.&mdash;<i>Spirifera sculptilis</i>. Devonian,
+Canada. (After Billings.)
+</span>
+
+<span style="width: 383px; vertical-align:top; text-align: center;
+  margin: 4px;">
+<img src="images/fig096.jpg" width="375" height="112" alt="Fig. 96" />
+<br />
+Fig. 96.&mdash;<i>Spirifera mucronata</i>. Devonian, America.
+(After Billings.)
+</span>
+
+</span>
+
+lateral angles prolonged to such an extent as to have earned for
+them the popular name of "fossil-butterflies." The closely-allied
+<i>Spirifera disjunda</i> occurs in Britain, France, Spain,
+Belgium, Germany, Russia, and China. The family of the
+<i>Productidœ</i> commenced to exist in the Upper Silurian,
+in the genus <i>Chonetes</i>, and we shall hereafter find it
+culminating in the Carboniferous in many forms of the great genus
+<i>Producta</i>[17] itself. In the Devonian period, there is an
+intermediate state of things, the genus <i>Chonetes</i> being
+continued in new and varied types, and the Carboniferous
+<i>Produdœ</i> being represented by many forms of the
+allied group <i>Productella</i>. Amongst other well-known
+Devonian Brachiopods may be mentioned the two long-lived and
+persistent types <i>Atrypa reticularis</i> (fig. 97) and
+<i>Strophomena rhomboidalis</i> (fig. 98). The former of these
+commences in the Upper Silurian, but is more abundantly developed
+in the Devonian, having a geographical range that is nothing less
+than world-wide; whilst the latter commences in the Lower Silurian,
+<a name="page_148"><span class="page">Page 148</span></a>
+and, with an almost equally cosmopolitan range, survives into the
+Carboniferous period.
+</p>
+
+<p class="footnote">
+[Footnote 17: The name of this genus is often written
+<i>Productus</i>, just as <i>Spirifera</i> is often given in the
+masculine gender as <i>Spirifer</i> (the name originally given
+to it). The masculine termination to these names is, however,
+grammatically incorrect, as the feminine noun <i>cochlea</i>
+(shell) is in these cases <i>understood</i>.]
+</p>
+
+<div class="center">
+<table border="0" width="489">
+<tr><td>
+<img src="images/fig097.jpg" width="485" height="158" alt="Fig. 97" />
+</td></tr>
+<tr><td class="center"><span class="image">
+Fig. 97.&mdash;<i>Atrypa reticularis</i>. Upper Silurian
+and Devonian of Europe and America. (After Billings.)
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+The Bivalves (<i>Lamellibranchiata</i>) of the Devonian call
+for no special comment, the genera <i>Pterinea</i> and
+<i>Megalodon</i> being, perhaps, the most noticeable. The Univalves
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 577px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig098.jpg" width="569" height="171" alt="Fig. 98" />
+<br />
+Fig. 98.&mdash;<i>Strophomena rhomboidalis</i>. Lower Silurian,
+Upper Silurian, and Devonian of Europe and America.
+</span>
+</span>
+
+(<i>Gasteropods</i>), also, need not be discussed in detail,
+though many interesting forms of this group are known. The type
+most abundantly represented, especially in America, is
+<i>Platyceras</i> (fig. 99), comprising thin, wide-mouthed shells,
+
+<span style="float: left; margin: 4px; width: 291px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig099.jpg" width="283" height="173" alt="Fig. 99" />
+<br />
+Fig. 99.&mdash;Different views of <i>Platyceras dumosum</i>, of
+the natural size. Devonian, Canada.  (Original.)
+</span>
+
+probably most nearly allied to the existing "Bonnet-limpets,"
+and sometimes attaining very considerable dimensions. We may
+also note the continuance of the genus <i>Euomphalus</i>, with
+its discoidal spiral shell. Amongst the <i>Heteropods</i>, the
+survival of <i>Bellerophon</i> is to be recorded; and in the
+"Winged-snails," or <i>Pteropods</i>, we find new forms of the
+old genera <i>Tentaculites</i> and <i>Conularia</i>
+<a name="page_149"><span class="page">Page 149</span></a>
+(fig. 100). The latter, with its fragile, conical, and often
+beautifully ornamented shell, is especially noticeable.
+</p>
+
+<p class="indent">
+The remains of <i>Cephalopoda</i> are far from uncommon in the
+
+<span style="float: right; margin: 4px; width: 179px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig100.jpg" width="171" height="273" alt="Fig. 100" />
+<br />
+Fig. 100.&mdash;<i>Conularia ornata</i>, of the natural size.
+Devonian, Europe.
+</span>
+
+Devonian deposits, all the known forms being still Tetrabranchiate.
+Besides the ancient types <i>Orthoceras</i> and <i>Cyrtoceras</i>,
+we have now a predominance of the spirally-coiled chambered shells
+of <i>Goniatites</i> and <i>Clymenia</i>. In the former of these the
+shell is shaped like that of the <i>Nautilus</i>; but the partitions
+between the chambers ("septa") are more or less lobed, folded, or
+angulated, and the "siphuncle" runs along the <i>back</i> or convex
+side of the shell&mdash;these being characters which approximate
+<i>Goniatites</i> to the true Ammonites of the later rocks. In
+<i>Clymenia</i>, on the other hand, whilst the shell (fig. 101)
+is coiled into a flat spiral, and the partitions or septa are
+simple or only slightly lobed, there is still this difference, as
+compared with the <i>Nautilus</i>, that the tube of the siphuncle
+is placed on the <i>inner</i> or concave side of the shell. The
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 322px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig101.jpg" width="314" height="388" alt="Fig. 101" />
+<br />
+Fig. 101.&mdash;<i>Clymenia Sedgwickii</i>. Devonian, Europe.
+</span>
+</span>
+
+species of <i>Clymenia</i> are exclusively Devonian in
+<a name="page_150"><span class="page">Page 150</span></a>
+their range; and some of the limestones of this period in Germany
+are so richly charged with fossils of this genus as to have received
+the name of "Clymenien-kalk."
+</p>
+
+<p class="indent">
+The sub-kingdom of the <i>Vertebrates</i> is still represented
+by <i>Fishes</i> only; but these are so abundant, and belong to
+such varied types, that the Devonian period has been appropriately
+called the "Age of Fishes." Amongst the existing fishes there are
+three great groups which are of special geological importance,
+as being more or less extensively represented in past time. These
+groups are: (1) The <i>Bony Fishes</i> (<i>Teleostei</i>), comprising
+most existing fishes, in which the skeleton is more or less
+completely converted into bone; the tail is symmetrically lobed
+or divided into equal moieties; and the scales are usually thin,
+horny, flexible plates, which overlap one another to a greater
+or less extent. (2) The <i>Ganoid Fishes</i> (<i>Ganoidei</i>),
+comprising the modern Gar-pikes, Sturgeons, &amp;c., in which the
+skeleton usually more or less completely retains its primitive
+soft and cartilaginous condition; the tail is generally markedly
+unsymmetrical, being divided into two unequal lobes; and the
+scales (when present) have the form of plates of bone, usually
+covered by a layer of shining enamel. These scales may overlap;
+or they may be rhomboidal plates, placed edge to edge in oblique
+rows; or they have the form of large-sized bony plates, which
+are commonly united in the region of the head to form a regular
+buckler. (3) The <i>Placoid Fishes</i>, or <i>Elasmobranchii</i>,
+comprising the Sharks, Rays, and <i>Chimœrœ</i> of
+the present day, in which the skeleton is cartilaginous; the tail
+is unsymmetrically lobed; and the scales have the form of detached
+bony plates of variable size, scattered in the integument.
+</p>
+
+<p class="indent">
+It is to the two last of these groups that the Devonian fishes
+belong, and they are more specially referable to the <i>Ganoids</i>.
+The order of the Ganoid fishes at the present day comprises but
+some seven or eight genera, the species of which principally or
+exclusively inhabit fresh waters, and all of which are confined
+to the northern hemisphere. As compared, therefore, with the Bony
+fishes, which constitute the great majority of existing forms,
+the Ganoids form but an extremely small and limited group. It was
+far otherwise, however, in Devonian times. At this period, the
+bony fishes are not known to have come into existence at all, and
+the Ganoids held almost undisputed possession of the waters. To
+what extent the Devonian Ganoids were confined to fresh waters
+remains yet to be proved; and that many of them lived in the sea
+is certain. It was formerly supposed that the Old Red Sandstone
+of Scotland and Ireland, with its abundant fish-remains, might
+perhaps be a fresh-water deposit, since the habitat of its fishes is
+<a name="page_151"><span class="page">Page 151</span></a>
+uncertain, and it contains no indubitable
+marine fossils. It has been now shown, however, that the marine
+Devonian strata of Devonshire and the continent of Europe contain
+some of the most characteristic of the Old Red Sandstone fishes of
+Scotland; whilst the undoubted marine deposit of the Corniferous
+limestone of North America contains numerous shark-like and Ganoid
+fishes, including such a characteristic Old Red genus as
+<i>Coccosleus</i>. There can be little doubt, therefore, but that
+the majority of the Devonian fishes were truly marine in their
+habits, though it is probable that many of them lived in shallow
+water, in the immediate neighbourhood of the shore, or in
+estuaries.
+</p>
+
+<p class="indent">
+The Devonian Galloids belong to a number of groups; and it is
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 561px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig102.jpg" width="553" height="544" alt="Fig. 102" />
+<br />
+Fig. 102.&mdash;Fishes of the Devonian rocks of America. <i>a</i>,
+Diagram of the jaws and teeth of <i>Dinichthys Hertzeri</i>,
+viewed from the front, and greatly reduced; <i>b</i>, Diagram
+of the skull of <i>Macropetalichthys Sullivanti</i>, reduced
+in size; <i>c</i>, A portion of the enamelled surface of the
+skull of the same, magnified; <i>d</i>, One of the scales of
+<i>Onychodus sigmoides</i>, of the natural size; <i>e</i>, One
+of the front teeth of the lower jaw of the same, of the natural
+size: <i>f</i>, Fin-spine of <i>Machœracanthus major</i>,
+a shark-like fish, reduced in size. (After Newberry.)]
+</span>
+</span>
+
+only possible to notice a few of the most important forms here.
+The modern group of the Sturgeons is represented,
+<a name="page_152"><span class="page">Page 152</span></a>
+more or less
+remotely, by a few Devonian fishes&mdash;such as <i>Asterosteus</i>;
+and the great <i>Macropetalichthys</i> of the Corniferous limestone
+of North America is believed by Newberry to belong to this group.
+In this fish (fig. 102, <i>b</i>) the skull was of large size,
+its outer surface being covered with a tuberculated enamel; and,
+as in the existing Sturgeons, the mouth seems to have been wholly
+destitute of teeth. Somewhat allied, also, to the Sturgeons, is a
+singular group of armoured fishes, which is highly characteristic
+of the Devonian of Britain and Europe, and less so of that of
+America. In these curious forms the head and front extremity of
+the body were protected by a buckler composed of large enamelled
+plates, more or less firmly united to one another; whilst the
+hinder end of the body was naked, or was protected with small
+scales. Some forms of this group&mdash;such as <i>Pteraspis</i>
+and <i>Coccosteus</i>&mdash;date from the Upper Silurian; but
+they attain their maximum in the Devonian, and none of them are
+known to pass upwards into the overlying Carboniferous rocks.
+Amongst the most characteristic forms of this group may be
+mentioned <i>Cephalaspis</i> (fig. 103) and <i>Pterichthys</i>
+(fig. 104). In the former of these the head-shield is of a
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 516px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig103.jpg" width="508" height="219" alt="Fig. 103" />
+<br />
+Fig. 103.&mdash;<i>Cephalaspis Lyellii</i>. Old Red Sandstone,
+Scotland. (After Page.)
+</span>
+</span>
+
+crescentic shape, having its hinder angles produced backwards
+into long "horns," giving it the shape of a "saddler's knife."
+No teeth have been discovered; but the body was covered with small
+ganoid scales, and there was an unsymmetrical tail-fin. In
+<i>Pterichthys</i>&mdash;which, like the preceding, was first
+brought to light by the labours of Hugh Miller&mdash;the whole
+of the head and the front part of the body were defended by a
+buckler of firmly-united enamelled plates, whilst the rest of the
+body was covered with small scales. The form of the "pectoral
+fins" was quite unique&mdash;these having the shape of two long,
+curved spines, somewhat like wings, covered by finely-tuberculated
+ganoid plates. All the preceding forms
+<a name="page_153"><span class="page">Page 153</span></a>
+of this group are of small size; but few fishes, living or extinct,
+could rival the proportions of the great <i>Dinichthys</i>, referred
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 490px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig104.jpg" width="482" height="189" alt="Fig. 104" />
+<br />
+Fig. 104.&mdash;<i>Pterichthys cornutus</i>. Old Red Sandstone,
+Scotland. (After Agassiz.)
+</span>
+</span>
+
+to this family by Newberry. In this huge fish (fig. 102, <i>a</i>)
+the head alone is over three feet in length, and the body is
+supposed to have been twenty-five or thirty feet long. The head
+was protected by a massive cuirass of bony plates firmly articulated
+together, but the hinder end of the body seems to have been simply
+enveloped in a leathery skin. The teeth are of the most formidable
+description, consisting in both jaws of serrated dental plates
+behind, and in front of enormous conical tusks (fig. 102, <i>a</i>).
+Though immensely larger, the teeth of <i>Dinichthys</i> present
+a curious resemblance to those of the existing Mud-fishes
+(<i>Lepidosiren</i>).
+</p>
+
+<p class="indent">
+In another great group of Devonian Ganoids, we meet with fishes
+more or less closely allied to the living <i>Polypteri</i> (fig.
+105) of the Nile and Senegal. In this group (fig. 106) the pectoral
+fins consist of a central scaly lobe carrying the fin-rays on both
+sides, the scales being sometimes rounded and overlapping (fig.
+106), or more commonly rhomboidal and placed edge to edge (fig. 105,
+A). Numerous forms of these "Fringe-finned" Ganoids occur in the
+Devonian strata, such as <i>Holoptychius, Glyotolœmus,
+Osteolepis, Phaneropleuron</i>, &amp;c. To this group is also to be
+ascribed the huge <i>Onychodus</i> (fig. 102, <i>d</i> and <i>e</i>),
+with its large, rounded, overlapping scales, an inch in diameter,
+and its powerful pointed teeth. It is to be remembered, however,
+that some of these "Fringe-finned" Ganoids are probably referable
+to the small but singular group of the "Mud-fishes" (<i>Dipnoi</i>),
+represented at the present day by the singular <i>Lepidosiren</i>
+of South America and Africa, and the <i>Ceratodus</i> of the
+rivers of Queensland.
+</p>
+
+<p class="indent">
+Leaving the Ganoid fishes, it still remains to be noticed that
+the Devonian deposits have yielded the remains of a number of
+fishes more or less closely allied to the existing Sharks,
+<a name="page_154"><span class="page">Page 154</span></a>
+Rays, and <i>Chimœrœ</i> (the <i>Elasmobranchii</i>).
+The majority of the forms here alluded to are allied not to the true
+Sharks and Dog-fishes, but to the more peaceable "Port Jackson
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 564px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig105.jpg" width="556" height="316" alt="Fig. 105" />
+<br />
+Fig. 105.&mdash;A, <i>Polypterus</i>, a recent Ganoid fish; B,
+<i>Osteolepis</i>, a Devonian Ganoid; <i>a a</i>, Pectoral
+fins, showing the fin-rays arranged round a central lobe.
+</span>
+</span>
+
+Sharks," with their blunt teeth, adapted for crushing the shells of
+Molluscs. The collective name of "Cestracionts" is applied to these;
+and we have evidence of their past existence in the Devonian seas
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 518px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig106.jpg" width="510" height="243" alt="Fig. 106" />
+<br />
+Fig. 106.&mdash;<i>Holoptychius nobilissimus</i>, restored. Old
+Red Sandstone, Scotland. A, Scale of the same.
+</span>
+</span>
+
+both by their teeth, and by the defensive spines which were implanted
+in front of a greater or less number of the fins. These are bony
+spines, often variously grooved, serrated, or ornamented, with
+hollow bases, implanted in the integument, and capable of being
+erected or depressed at will.
+<a name="page_155"><span class="page">Page 155</span></a>
+Many of these "fin-spines" have been preserved to us in the fossil
+condition, and the Devonian rocks have yielded examples belonging to
+many genera. As some of the true Sharks and Dog-fishes, some of the
+Ganoids, and even some Bony Fishes, possess similar defences, it is
+often a matter of some uncertainty to what group a given spine is
+to be referred. One of these spines, belonging to the genus
+<i>Machœracanthus</i>, from the Devonian rocks of America, has
+been figured in a previous illustration (fig. 102, <i>f</i>).
+</p>
+
+<p class="indent">
+In conclusion, a very few words may be said as to the validity of
+the Devonian series as an independent system of rocks, preserving
+in its successive strata the record of an independent system
+of life. Some high authorities have been inclined to the view
+that the Devonian formation has in nature no actual existence,
+but that it is made up partly of beds which should be referred
+to the summit of the Upper Silurian, and partly of beds which
+properly belong to the base of the Carboniferous. This view seems
+to have been arrived at in consequence of a too exclusive study
+of the Devonian series of the British Isles, where the physical
+succession is not wholly clear, and where there is a striking
+discrepancy between the organic remains of those two members
+of the series which are known as the "Old Red Sandstone" and
+the "Devonian" rocks proper. This discrepancy, however, is not
+complete; and, as we have seen, can be readily explained on the
+supposition that the one group of rocks presents us with the
+shallow water and littoral deposits of the period, while in the
+other we are introduced to the deep-sea accumulations of the
+same period. Nor can the problem at issue be solved by an appeal
+to the phenomena of the British area alone, be the testimony of
+these what it may. As a matter of fact, there is at present no
+sufficient ground for believing that there is any irreconcilable
+discordance between the succession of rocks and of life in Britain
+during the period which elapsed between the deposition of the
+Upper Ludlow and the formation of the Carboniferous Limestone,
+and the order of the same phenomena during the same period in
+other regions. Some of the Devonian types of life, as is the
+case with all great formations, have descended unchanged from
+older types; others pass upwards unchanged to the succeeding
+period: but the fauna and flora of the Devonian period are, as
+a whole, quite distinct from those of the preceding Silurian or
+the succeeding Carboniferous; and they correspond to an equally
+distinct rock-system, which in point of time holds an intermediate
+position between the two great groups just mentioned. As
+<a name="page_156"><span class="page">Page 156</span></a>
+before remarked, this conclusion may be regarded
+as sufficiently proved even by the phenomena of the British area;
+but it maybe said to be rendered a certainty by the study of the
+Devonian deposits of the continent of Europe&mdash;or, still more,
+by the investigation of the vast, for the most part uninterrupted
+and continuous series of sediments which commenced to be laid
+down in North America at the beginning of the Upper Silurian,
+and did not cease till, at any rate, the close of the Carboniferous.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following list comprises the more important works and memoirs
+to which the student of Devonian rocks and fossils may
+refer:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Siluria.' Sir Roderick Murchison.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Geology of Russia in Europe.' Murchison (together with De
+  Verneuil and Count von Keyserling).</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>"Classification of the Older Rocks of Devon and
+  Cornwall"&mdash;'Proc. Geol. Soc.,' vol. iii., 1839. Sedgwick
+  and Murchison.</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>"On the Physical Structure of Devonshire;" and on the
+  "Classification of the Older Stratified Rocks of Devonshire
+  and Cornwall"&mdash;'Trans. Geol. Soc.,' vol. v., 1840. Sedgwick
+  and Murchison.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>"On the Distribution and Classification of the Older or
+  Palæozoic Rocks of North Germany and Belgium"&mdash;'Geol.
+  Trans.,' 2d ser., vol. vi., 1842. Sedgwick and
+  Murchison.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>'Report on the Geology of Cornwall, Devon, and West
+  Somerset.' De la Beche.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>'Memoirs of the Geological Survey of Ireland and
+  Scotland.' Jukes and Geikie.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>"On the Carboniferous Slate (or Devonian Rocks) and the
+  Old Red Sandstone of South Ireland and North Devon"&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. xxii. Jukes.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>"On the Physical Structure of West Somerset and North
+  Devon;" and on the "Palæontological Value of Devonian
+  Fossils"&mdash;'Quart. Journ. Geol. Soc.,' vol. iii.
+  Etheridge.</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>"On the Connection of the Lower, Middle, and Upper Old Red
+  Sandstone of Scotland"&mdash;'Trans. Edin. Geol. Soc.,' vol. i.
+  part ii. Powrie.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'The Old Red Sandstone,' 'The Testimony of the Rocks,' and
+  'Footprints of the Creator.' Hugh Miller.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>"Report on the 4th Geological District"&mdash;'Geology of
+  New York,' vol. iv. James Hall.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>'Geology of Canada,' 1863. Sir W. E. Logan.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>'Acadian Geology.' Dawson.</td></tr>
+<tr><td class="right" valign="top">(15)</td>
+ <td>'Manual of Geology.' Dana.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Geological Survey of Ohio,' vol. i.</td></tr>
+<tr><td class="right" valign="top">(17)</td>
+ <td>'Geological Survey of Illinois,' vol. i.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>'Palæozoic Fossils of Cornwall, Devon, and West
+  Somerset.' Phillips.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>'Recherches sur les Poissons Fossiles.' Agassiz.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>'Poissous de l'Old Red.' Agassiz.</td></tr>
+<tr><td class="right" valign="top">(21)</td>
+ <td>"On the Classification of Devonian Fishes"&mdash;'Mem. Geol.
+  Survey of Great Britain,' Decade X. Huxley.</td></tr>
+<tr><td class="right" valign="top">
+<a name="page_157"><span class="page">Page 157</span></a>
+  (22)</td>
+ <td>'Monograph of the Fishes of the Old Red Sandstone of
+  Britain' (Palæontographical Society). Powrie and
+  Lankester.</td></tr>
+<tr><td class="right" valign="top">(23)</td>
+ <td>'Fishes of the Devonian System, Palæontology of
+  Ohio.' Newberry.</td></tr>
+<tr><td class="right" valign="top">(24)</td>
+ <td>'Monograph of British Trilobites'
+  (Palæontographical Society); Salter.</td></tr>
+<tr><td class="right" valign="top">(25)</td>
+ <td>'Monograph of British Merostomata'
+  (Palæontographical Society). Henry Woodward.</td></tr>
+<tr><td class="right" valign="top">(26)</td>
+ <td>'Monograph of British Brachiopoda'
+  (Palæontographical Society). Davidson.</td></tr>
+<tr><td class="right" valign="top">(27)</td>
+ <td>'Monograph of British Fossil Corals'
+  (Palæontographical Society). Milne-Edwards and
+  Haime.</td></tr>
+<tr><td class="right" valign="top">(28)</td>
+ <td>'Polypiers Foss. des Terrains Paléozoiques.'
+  Milne-Edwards and Jules Haime.</td></tr>
+<tr><td class="right" valign="top">(29)</td>
+ <td>"Devonian Fossils of Canada West"&mdash;'Canadian
+  Journal,' new ser., vols. iv.-vi. Billings.</td></tr>
+<tr><td class="right" valign="top">(30)</td>
+ <td>'Palæontology of New York,' vol. iv. James
+  Hall.</td></tr>
+<tr><td class="right" valign="top">(31)</td>
+ <td>'Thirteenth, Fifteenth, and Twenty-third Annual Reports
+  on the State Cabinet.' James Hall.</td></tr>
+<tr><td class="right" valign="top">(32)</td>
+ <td>'Palæozoic Fossils of Canada,' vol. ii.
+  Billings.</td></tr>
+<tr><td class="right" valign="top">(33)</td>
+ <td>'Reports on the Palæontology of the Province of
+  Ontario for 1874 and 1875.' Nicholson.</td></tr>
+<tr><td class="right" valign="top">(34)</td>
+ <td>"The Fossil Plants of the Devonian and Upper Silurian
+  Formations of Canada"&mdash;'Geol. Survey of Canada.'
+  Dawson.</td></tr>
+<tr><td class="right" valign="top">(35)</td>
+ <td>'Petrefacta Germaniæ.' Goldfuss.</td></tr>
+<tr><td class="right" valign="top">(36)</td>
+ <td>'Versteinerungen der Grauwacken-formation.' &amp;c.
+  Geinitz.</td></tr>
+<tr><td class="right" valign="top">(37)</td>
+ <td>'Beitrag zur Palæontologie des Th&uuml;ringer-Waldes.'
+  Richter and Unger.</td></tr>
+<tr><td class="right" valign="top">(38)</td>
+ <td>'Ueber die Placodermen der Devonischen System.'
+  Pander.</td></tr>
+<tr><td class="right" valign="top">(39)</td>
+ <td>'Die Gattungen der Fossilen Pflanzen.'
+  Gœppert.</td></tr>
+<tr><td class="right" valign="top">(40)</td>
+ <td>'Genera et Species Plantarum Fossilium.'
+  Unger.</td></tr>
+</table>
+
+<h3>CHAPTER XII.</h3>
+
+<p class="subtitle">
+THE CARBONIFEROUS PERIOD.
+</p>
+
+<p class="indent">
+Overlying the Devonian formation is the great and important series
+of the <i>Carboniferous Rocks</i>, so called because workable
+beds of coal are more commonly and more largely developed in this
+formation than in any other. Workable coal-seams, however, occur
+in various other formations (Jurassic, Cretaceous, Tertiary), so
+that coal is not an exclusively Carboniferous product; whilst
+even in the Coal-measures themselves the coal bears but a very
+small proportion to the total thickness of strata, occurring
+only in comparatively thin beds intercalated in a great series
+of sandstones, shales, and other genuine aqueous sediments.
+</p>
+
+<p class="indent">
+<a name="page_158"><span class="page">Page 158</span></a>
+Stratigraphically, the Carboniferous rocks usually repose
+conformably upon the highest Devonian beds, so that the line of
+demarcation between the Carboniferous and Devonian formations is
+principally a palæontological one, founded on the observed
+differences in the fossils of the two groups. On the other hand,
+the close of the Carboniferous period seems to have been generally,
+though not universally, signalised by movements of the crust of
+the earth, so that the succeeding Permian beds often lie
+unconformably upon the Carboniferous sediments.
+</p>
+
+<p class="indent">
+Strata of Carboniferous age have been discovered in almost every
+large land-area which has been sufficiently investigated; but
+they are especially largely developed in Britain, in various
+parts of the continent of Europe, and in North America. Their
+general composition, however, is, comparatively speaking, so
+uniform, that it will suffice to take a comprehensive view of
+the formation without considering any one area in detail, though
+in each region the subdivisions of the formation are known by
+distinctive local names. Taking such a comprehensive view, it
+is found that the Carboniferous series is generally divisible
+into a <i>Lower</i> and essentially calcareous group (the
+"Sub-Carboniferous" or "Carboniferous Limestone"); a <i>Middle</i>
+and principally arenaceous group (the "Millstone Grit"); and an
+Upper group, of alternating shales and sandstones, with workable
+seams of coal (the "Coal-measures").
+</p>
+
+<p class="indent">
+I. The <i>Carboniferous, Sub-Carboniferous</i>, or <i>Mountain
+Limestone Series</i> constitutes the general base of the
+Carboniferous system. As typically developed in Britain, the
+Carboniferous Limestone is essentially a calcareous formation,
+sometimes consisting of a mass of nearly pure limestone from
+1000 to 2000 feet in thickness, or at other times of successive
+great beds of limestone with subordinate sandstones and shales.
+In the north of England the base of the series consists of pebbly
+conglomerates and coarse sandstones; and in Scotland generally,
+the group is composed of massive sandstones with a comparatively
+feeble development of the calcareous element. In Ireland, again,
+the base of the Carboniferous Limestone is usually considered
+to be formed by a locally-developed group of grits and shales
+(the "Coomhola Grits" and "Carboniferous Slate"), which attain
+the thickness of about 5000 feet, and contain an intermixture
+of Devonian with Carboniferous types of fossils. Seeing that the
+Devonian formation is generally conformable to the Carboniferous,
+we need feel no surprise at this intermixture of forms; nor does it
+<a name="page_159"><span class="page">Page 159</span></a>
+appear to be of great moment whether these
+strata be referred to the former or to the latter series. Perhaps
+the most satisfactory course is to regard the Coomhola Grits and
+Carboniferous Slates as "passage-beds" between the Devonian and
+Carboniferous; but any view that may be taken as to the position
+of these beds, really leaves unaffected the integrity of the
+Devonian series as a distinct life-system, which, on the whole,
+is more closely allied to the Silurian than to the Carboniferous.
+In North America, lastly, the Sub-Carboniferous series is never
+purely calcareous, though in the interior of the continent it
+becomes mainly so. In other regions, however, it consists
+principally of shales and sandstones, with subordinate beds of
+limestone, and sometimes with this beds of coal or deposits of
+clay-ironstone.
+</p>
+
+<p class="indent">
+II. <i>The Millstone Grit</i>.&mdash;The highest beds of the
+Carboniferous Limestone series are succeeded, generally with
+perfect conformity, by a series of arenaceous beds, usually
+known as the <i>Millstone Grit</i>. As typically developed in
+Britain, this group consists of hard quartzose sandstones,
+often so large-grained and coarse in texture as to properly
+constitute fine conglomerates. In other cases there are regular
+conglomerates, sometimes with shales, limestones, and thin beds
+of coal&mdash;the thickness of the whole series, when well
+developed, varying from 1000 to 5000 feet. In North America,
+the Millstone Grit rarely reaches 1000 feet in thickness; and,
+like its British equivalent, consists of coarse sandstones
+and grits, sometimes with regular conglomerates. Whilst the
+Carboniferous Limestone was undoubtedly deposited in a tranquil
+ocean of considerable depth, the coarse mechanical sediments
+of the Millstone Grit indicate the progressive shallowing of
+the Carboniferous seas, and the consequent supervention of
+shore-conditions.
+</p>
+
+<p class="indent">
+III. <i>The Coal-measures</i>.&mdash;The Coal-measures properly
+so called rest conformably upon the Millstone Grit, and usually
+consist of a vast series of sandstones, shales, grits, and coals,
+sometimes with beds of limestone, attaining in some regions a total
+thickness of from 7000 to nearly 14,000 feet. Beds of workable
+coal are by no means unknown in some areas in the inferior group
+of the Sub-Carboniferous; but the general statement is true,
+that coal is mostly obtained from the true Coal-measures&mdash;the
+largest known, and at present most productive coal-fields of the
+world being in Great Britain, North America, and Belgium. Wherever
+they are found, with limited exceptions, the Coal-measures present
+a singular <i>general</i> uniformity of mineral composition. They
+<a name="page_160"><span class="page">Page 160</span></a>
+consist, namely, of an indefinite alternation
+of beds of sandstone, shale, and coal, sometimes with bands of
+clay-ironstone or beds of limestone, repeated in no constant
+order, but sometimes attaining the enormous aggregate thickness
+of 14,000 feet, or little short of 3 miles. The beds of coal
+differ in number and thickness in different areas, but they
+seldom or never exceed one-fiftieth part of the total bulk of
+the formation in thickness. The characters of the coal itself,
+and the way in which the coal-beds were deposited, will be
+briefly alluded to in speaking of the vegetable life of the
+period. In Britain, and in the Old World generally, the
+Coal-measures are composed partly of genuine terrestrial
+deposits&mdash;such as the coal&mdash;and partly of sediments
+accumulated in the fresh or brackish waters of vast lagoons,
+estuaries, and marshes. The fossils of the Coal-measures in these
+regions are therefore necessarily the remains either of terrestrial
+plants and animals, or of such forms of life as inhabit fresh or
+brackish waters, the occurrence of strata with marine fossils being
+quite a local and occasional phenomenon. In various parts of North
+America, on the other hand, the Coal-measures, in addition to
+sandstones, shales, coal-seams, and bands of clay-ironstone,
+commonly include beds of limestone, charged with marine remains,
+and indicating marine conditions. The subjoined section (fig. 107)
+gives, in a generalised form, the succession of the Carboniferous
+strata in such a British area as the north of England, where
+the series is developed in a typical form.
+</p>
+
+<p class="indent">
+As regards the <i>life</i> of the Carboniferous period, we naturally
+find, as has been previously noticed, great differences in different
+parts of the entire series, corresponding to the different mode of
+origin of the beds. Speaking generally, the Lower Carboniferous
+(or the Sub-Carboniferous) is characterised by the remains of
+marine animals; whilst the Upper Carboniferous (or Coal-measures)
+is characterised by the remains of plants and terrestrial animals.
+In all those cases, however, in which marine beds are found in
+the series of the Coal-measures, as is common in America, then
+we find that the fossils agree in their general characters with
+those of the older marine deposits of the period.
+</p>
+
+<p class="indent">
+Owing to the fact that coal is simply compressed and otherwise
+altered vegetable matter, and that it is of the highest economic
+value to man, the Coal-measures have been more thoroughly explored
+than any other group of strata of equivalent thickness in the
+entire geological series. Hence we have already a very extensive
+acquaintance with the <i>plants</i> of the Carboniferous period;
+and our knowledge on this subject is
+<a name="page_161"><span class="page">Page 161</span></a>
+daily undergoing increase. It is not to be supposed, however,
+that the remains of plants are found solely in Coal-measures;
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 544px;
+  font-size: smaller; text-align: center;">
+GENERALIZED SECTION OF THE CARBONIFEROUS STRATA OF THE NORTH OF
+ENGLAND.
+<br />
+Fig. 107.
+<br />
+<img src="images/fig107.jpg" width="536" height="697" alt="Fig. 107" />
+</span>
+</span>
+
+for though most abundant towards the summit, they are found in
+less numbers in all parts of the series. Wherever found, they
+belong to the same great types of
+<a name="page_162"><span class="page">Page 162</span></a>
+vegetation; but, before reviewing these, a few words must be
+said as to the origin and mode of formation of <i>coal</i>.
+</p>
+
+<p class="indent">
+The coal-beds, as before mentioned, occur interstratified with
+shales, sandstones, and sometimes limestones; and there may,
+within the limits of a single coal-field, be as many as 80 or
+100 of such beds, placed one above the other at different levels,
+and varying in thickness from a few inches up to 20 or 30 feet.
+As a general rule, each bed of coal rests upon a bed of shale or
+clay, which is termed the "under-clay," and in which are found
+numerous roots of plants; whilst the strata immediately on the
+top of the coal may be shaly or sandy, but in either case are
+generally charged with the leaves and stems of plants, and often
+have upright trunks passing vertically through them. When we
+add to this that the coal itself is, chemically, nearly wholly
+composed of carbon, and that its microscopic structure shows it
+to be composed almost entirely of fragments of stems, leaves,
+bark, seeds, and vegetable <i>débris</i> derived from
+<i>land-plants</i>, we are readily enabled to understand how the
+coal was formed. The "<i>under-clay</i>" immediately beneath the
+coal-bed represents an old land-surface&mdash;sometimes, perhaps,
+the bottom of a swamp or marsh, covered with a luxuriant vegetation;
+the <i>coal bed</i> itself represents the slow accumulation,
+through long periods, of the leaves, seeds, fruits, stems, and
+fallen trunks of this vegetation, now hardened and compressed
+into a fraction of its original bulk by the pressure of the
+superincumbent rocks; and the strata of sand or shale above the
+coal-bed&mdash;the so-called "roof" of the coal&mdash;represent
+sediments quietly deposited as the land, after a long period of
+repose, commenced to sink beneath the sea. On this view, the rank
+and long-continued vegetation which gave rise to each coal-bed
+was ultimately terminated by a slow depression of the surface on
+which the plants grew. The land-surface then became covered by
+the water, and aqueous sediments were accumulated to a greater
+or less thickness upon the dense mass of decaying vegetation
+below, enveloping any trunks of trees which might still be in an
+erect position, and preserving between their layers the leaves
+and branches of plants brought down from the neighbouring land by
+streams, or blown into the wafer by the wind. Finally, there set in
+a slow movement of elevation,&mdash;the old land again reappeared
+above the water; a new and equally luxuriant vegetation flourished
+upon the new land-surface; and another coal-bed was accumulated,
+to be preserved ultimately in a similar fashion. Some few beds
+of coal may have been formed by drifted vegetable matter brought
+down into the ocean by rivers,
+<a name="page_163"><span class="page">Page 163</span></a>
+and deposited
+directly on the bottom of the sea; but in the majority of cases
+the coal is undeniably the result of the slow growth and decay of
+plants <i>in situ</i>: and as the plants of the coal are not
+<i>marine</i> plants, it is necessary to adopt some such theory
+as the above to account for the formation of coal-seams. By this
+theory, as is obvious, we are compelled to suppose that the vast
+alluvial and marshy flats upon which the coal-plants grew were
+liable to constantly-recurring oscillations of level, the successive
+land-surfaces represented by the successive coal-beds of any
+coal-field being thus successively buried beneath accumulations
+of mud or sand. We have no need, however, to suppose that these
+oscillations affected large areas at the same time; and geology
+teaches us that local elevations and depressions of the land
+have been matters of constant occurrence throughout the whole
+of past time.
+</p>
+
+<p class="indent">
+All the varieties of coal (bituminous coal, anthracite; cannel-coal,
+&amp;c.) show a more or less distinct "lamination"&mdash;that is to
+say, they are more or less obviously composed of successive thin layers,
+differing slightly in colour and texture. All the varieties of coal,
+also, consist chemically of <i>carbon</i>, with varying proportions
+of certain gaseous constituents and a small amount of incombustible
+mineral or "ash." By cutting thin and transparent slices of coal,
+we are further enabled, by means of the microscope, to ascertain
+precisely not only that the carbon of the coal is derived from
+vegetables, but also, in many cases, what kinds of plants, and what
+parts of these, enter into the formation of coal. When examined
+in this way, all coals are found to consist more or less entirely
+of vegetable matter; but there is considerable difference in
+different coals as to the exact nature of this. By Professor
+Huxley it has been shown that many of the English coals consist
+largely of accumulations of rounded discoidal sacs or bags, which
+are unquestionably the seed-vessels or "spore-cases" of certain
+of the commoner coal-plants (such as the <i>Lepidodendra</i>).
+The best bituminous coals seem to be most largely composed of
+these spore-cases; whilst inferior kinds possess a progressively
+increasing amount of the dull carbonaceous substance which is
+known as "mineral charcoal," and which is undoubtedly composed
+of "the stems and leaves of plants reduced to little more than
+their carbon." On the other hand, Principal Dawson finds that
+the American coals only occasionally exhibit spore-cases to any
+extent, but consist principally of the cells, vessels, and fibres
+of the bark, integumentary coverings, and woody portions of the
+Carboniferous plants.
+</p>
+
+<p class="indent">
+The number of plants already known to have existed
+<a name="page_164"><span class="page">Page 164</span></a>
+during the Carboniferous period is so great, that
+nothing more can be done here than to notice briefly the typical
+and characteristic <i>groups</i> of these&mdash;such as the
+Ferns, the Calamites, the Lepidodendroids, the Sigillarioids,
+and the Conifers.
+</p>
+
+<p class="indent">
+In accordance with M. Brongniart's generalisation, that the
+Palæozoic period is, botanically speaking, the "Age of
+Acrogens," we find the Carboniferous plants to be still mainly
+referable to the Flowerless or "Cryptogamous" division of the
+vegetable kingdom. The flowering or "Phanerogamous" plants,
+which form the bulk of our existing vegetation, are hardly known,
+with certainty, to have existed at all in the Carboniferous era,
+except as represented by trees related to the existing Pines and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 449px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig108.jpg" width="441" height="347" alt="Fig. 108" />
+<br />
+Fig. 108.&mdash;<i>Odontopteris Schlotheimii</i>. Carboniferous,
+Europe and North America.
+</span>
+</span>
+
+Firs, and possibly by the Cycads or "false palms."[18] Amongst
+the "Cryptogams," there is no more striking or beautiful group of
+Carboniferous plants than the <i>Ferns</i>. Remains of these are
+found all through the Carboniferous, but in exceptional numbers
+in the Coal-measures, and include both herbaceous forms like the
+majority of existing species, and arborescent forms resembling
+the living Tree-ferns of New Zealand. Amongst the latter, together
+with some new types, are examples of the genera <i>Psaronius</i>
+and <i>Caulopteris</i>, both of
+<a name="page_165"><span class="page">Page 165</span></a>
+which date from the Devonian. The simply herbaceous ferns are
+extremely numerous, and belong to such widely-distributed and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 477px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig109.jpg" width="469" height="746" alt="Fig. 109" />
+<br />
+Fig. 109.&mdash;<i>Calamites cannœformis</i>. Carboniferous
+Rocks, Europe and North America.
+</span>
+</span>
+
+largely-represented genera as <i>Neuropteris, Odontopteris</i>
+(fig. 108), <i>Alethopteris, Pecopteris, Sphenopteris,
+Hymenophyllites</i>, &amp;c.
+</p>
+
+<p class="footnote">
+[Footnote 18: Whilst the vegetation of the Coal-period was mainly
+a terrestrial one, aquatic plants are not unknown. Sea-weeds (such
+as the <i>Spirophyton cauda-Galli</i>) are common in some of the
+marine strata; whilst coal, according to the researches of the
+Abbé Castracane, is asserted commonly to contain the
+siliceous envelopes of Diatoms.]
+</p>
+
+<p class="indent">
+The fossils known as <i>Calamites</i> (fig. 109) are very common
+<a name="page_166"><span class="page">Page 166</span></a>
+in the Carboniferous deposits, and have given
+occasion to an abundance of research and speculation. They present
+themselves as prostrate and flattened striated stems, or as similar
+uncompressed stems growing in an erect position, and sometimes
+attaining a length of twenty feet or more. Externally, the stems
+are longitudinally ribbed, with transverse joints at regular
+intervals, these joints giving origin to a whorl or branchlets,
+which mayor may not give origin to similar whorls of smaller
+branchlets still. The stems, further, were hollow, with transverse
+partitions at the joints, and having neither true wood nor bark,
+but only a thin external fibrous shell. There can be little doubt
+but that the <i>Calamites</i> are properly regarded as colossal
+representatives of the little Horse-tails (<i>Equisetaceœ</i>)
+of the present day. They agree with these not only in the general
+details of their organisation, but also in the fact that the fruit
+was a species of cone, bearing "spore-cases" under scales.
+According to Principal Dawson, the <i>Calamites</i> "grew in
+dense brakes on the sandy and muddy flats, subject to inundation,
+or perhaps even in water; and they had the power of budding out
+from the base of the stem, so as to form clumps of plants, and
+also of securing their foothold by numerous cord-like roots
+proceeding from various heights on the lower part of the stem."
+</p>
+
+<p class="indent">
+The <i>Lepidodendroids</i>, represented mainly by the genus
+<i>Lepidodendron</i> itself (fig. 110), were large tree-like
+plants, which attain their maximum in the Carboniferous period,
+but which appear to commence in the Upper Silurian, are well
+represented in the Devonian, and survive in a diminished form into
+the Permian. The trunks of the larger species of <i>Lepidodendron</i>
+at times reach a length of fifty feet and upwards, giving off
+branches in a regular bifurcating manner. The bark is marked
+with numerous rhombic or oval scars, arranged in quincunx order,
+and indicating the points where the long, needle-shaped leaves
+were formerly attached. The fruit consisted of cones or spikes,
+carried at the ends of the branches, and consisting of a central
+axis surrounded by overlapping scales, each of which supports
+a "spore-case" or seed-vessel. These cones have commonly been
+described under the name of <i>Lepidostrobi</i>. In the structure
+of the trunk there is nothing comparable to what is found in
+existing trees, there being a thick bark surrounding a zone
+principally composed of "scalariform" vessels, this in turn
+enclosing a large central pith. In their general appearance the
+<i>Lepidodendra</i> bring to mind the existing Araucarian Pines;
+but they are true "Cryptogams," and are to be regarded as a
+gigantic extinct type of the
+<a name="page_167"><span class="page">Page 167</span></a>
+modern Club-mosses (<i>Lycopodiaceœ</i>). They are amongst
+the commonest and most characteristic of the Carboniferous
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 505px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig110.jpg" width="497" height="738" alt="Fig. 110" />
+<br />
+Fig. 110.&mdash;<i>Lepidodendron Sternbergii</i>, Carboniferous,
+Europe. The central figure represents a portion of the trunk with
+its branches, much reduced in size. The right-hand figure is a
+portion of a branch with the leaves partially attached to it; and
+the left-hand figure represents the end of a branch bearing a cone
+of fructification.
+</span>
+</span>
+
+plants; and the majority of the "spore-cases" so commonly found
+in the coal appear to have been derived from the cones of
+Lepidodendroids.
+</p>
+
+<p class="indent">
+<a name="page_168"><span class="page">Page 168</span></a>
+The so-called <i>Sigillanoids</i>, represented
+mainly by <i>Sigillaria</i> itself (fig. 111), were no less
+abundant and characteristic of the Carboniferous forests than the
+<i>Lepidodendra</i>. They commence their existence, so far as
+known, in the Devonian period, but they attain their maximum in the
+Carboniferous; and&mdash;unlike the Lepidodendroids&mdash;they are
+not known to occur in the Permian period. They are comparatively
+gigantic in size, often attaining a height of from thirty to
+fifty feet or more; but though abundant and well preserved, great
+divergence of opinion prevails as to their true affinities. The
+<i>name</i> of Sigillarioids (Lat. <i>sigilla</i>, little seals
+or images) is derived from the fact that the bark is marked with
+seal-like impressions or leaf-scars (fig. 111).
+</p>
+
+<p class="indent">
+Externally, the trunks of <i>Sigillaria</i> present strong
+longitudinal ridges, with vertical alternating rows of oval
+leaf-scars indicating the points where the leaves were originally
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 373px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig111.jpg" width="365" height="337" alt="Fig. 111" />
+<br />
+Fig. 111.&mdash;Fragment of the external surface of <i>Sigillaria
+Grœseri</i>, showing the ribs and leaf-scars. The left-hand
+figure represents a small portion enlarged. Carboniferous,
+Europe.
+</span>
+</span>
+
+attached. The trunk was furnished with a large central pith, a thick
+outer bark, and an intermediate woody zone,&mdash;composed, according
+to Dawson, partly of the disc-bearing fibres so characteristic of
+Conifers; but, according to Carruthers, entirely made up of the
+"scalariform" vessels characteristic of Cryptogams. The size of the
+pith was very great, and the bark seems to have been the most
+durable portion of the trunk. Thus we have evidence that in many
+cases the stumps and "stools" of <i>Sigillariœ</i>, standing
+<a name="page_169"><span class="page">Page 169</span></a>
+upright in the old Carboniferous swamps, were
+completely hollowed out by internal decay, till nothing but an
+exterior shell of bark was left. Often these hollow stumps became
+ultimately filled up with sediment, sometimes enclosing the remains
+of galley-worms, land-snails, or Amphibians, which formerly found in
+the cavity of the trunk a congenial home; and from the sandstone or
+shale now filling such trunks some of the most interesting fossils
+of the Coal-period have been obtained. There is little certainty as
+to either the leaves or fruits of <i>Sigillaria</i>, and there
+is equally little certainty as to the true botanical position of
+these plants. By Principal Dawson they are regarded as being
+probably flowering plants allied to the existing "false palms"
+or "<i>Cycads</i>," but the high authority of Mr Carruthers is to
+be quoted in support of the belief that they are Cryptogamic,
+and most nearly allied to the Club-mosses.
+</p>
+
+<p class="indent">
+Leaving the botanical position of <i>Sigillaria</i> thus undecided,
+we find that it is now almost universally conceded that the fossils
+originally described under the name of <i>Stigmaria</i> are the
+<i>roots</i> of <i>Sigillaria</i>, the actual connection between
+the two having been in numerous instances demonstrated in an
+unmistakable manner. The <i>Stigmariœ</i> (fig. 112) ordinarily
+present themselves in the form of long, compressed or rounded
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 386px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig112.jpg" width="378" height="227" alt="Fig. 112" />
+<br />
+Fig. 112.&mdash;<i>Stigmaria ficoides</i>. Quarter natural size.
+Carboniferous.
+</span>
+</span>
+
+fragments, the external surface of which is covered with rounded
+pits or shallow tubercles, each of which has a little pit or
+depression in its centre. From each of these pits there proceeds,
+in perfect examples, a long cylindrical rootlet; but in many cases
+these have altogether disappeared. In their internal structure,
+<i>Stigmaria</i> exhibits a central pith surrounded by a sheath of
+scalariform vessels, the whole enclosed in a cellular envelope.
+The <i>Stigmariœ</i> are generally found ramifying in
+<a name="page_170"><span class="page">Page 170</span></a>
+the "under-clay," which forms the floor of a
+bed of coal, and which represents the ancient soil upon which the
+<i>Sigillariœ</i>
+grew.
+</p>
+
+<p class="indent">
+The <i>Lepidodendroids</i> and <i>Sigillaroids</i>, though the first
+were certainly, and the second possibly, Cryptogamic or flowerless
+plants, must have constituted the main mass of the forests of
+the Coal period; but we are not without evidence of the existence
+at the same time of genuine "trees," in the technical sense of
+this term&mdash;namely, flowering plants with large woody stems. So
+far as is certainly known, all the true trees of the Carboniferous
+formation were <i>Conifers</i>, allied to the existing Pines and
+Firs. They are recognised by the great size and concentric woody
+rings of their prostrate, rarely erect trunks, and by the presence
+of disc-bearing fibres in their wood, as demonstrated by the
+microscope; and the principal genera which have been recognised are
+<i>Dadoxylon, Palœoxylon, Araucarioxylon</i>, and <i>Pinites</i>.
+Their fruit is not known with absolute certainty, unless it be
+represented, as often conjectured, by <i>Trigonocarpon</i> (fig.
+113). The fruits known under this name are nut-like, often of
+
+<span style="float: left; margin: 4px; width: 187px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig113.jpg" width="179" height="117" alt="Fig. 113" />
+<br />
+Fig. 113.&mdash;<i>Trigonocarpon ovatum</i>. Coal-measures, Britain.
+(After Liudley and Hutton.)
+</span>
+
+considerable size, and commonly three- or six-angled. They probably
+originally possessed a fleshy envelope; and if truly referable
+to the <i>Conifers</i>, they would indicate that these ancient
+evergreens produced berries instead of cones, and thus resembled
+the modern Yews rather than Pines. It seems, further, that the
+great group of the <i>Cycads</i>, which are nearly allied to the
+<i>Conifers</i>, and which attained such a striking prominence in
+the Secondary period, probably commenced its existence during the
+Coal period; but these anticipatory forms are comparatively few
+in number, and for the most part of somewhat dubious affinities.
+</p>
+
+<h3>CHAPTER XIII.</h3>
+
+<p class="subtitle">
+THE CARBONIFEROUS PERIOD&mdash;<i>Continued</i>.
+</p>
+
+<p class="center">
+ANIMAL LIFE OF THE CARBONIFEROUS.
+</p>
+
+<p class="indent">
+We have seen that there exists a great difference as to the mode
+of origin of the Carboniferous sediments, some being purely marine,
+whilst others are terrestrial; and others, again,
+<a name="page_171"><span class="page">Page 171</span></a>
+have been formed in inland swamps and morasses, or in
+brackish-water lagoons, creeks, or estuaries. A corresponding
+difference exists necessarily in the animal remains of these
+deposits, and in many regions this difference is extremely well
+marked and striking. The great marine limestones which
+characterise the lower portion of the Carboniferous series in
+Britain, Europe, and the eastern portion of America, and the
+calcareous beds which are found high up in the Carboniferous in
+the western States of America, may, and do, often contain the
+remains of drifted plants; but they are essentially characterised
+by marine fossils; and, moreover, they can be demonstrated by
+the microscope to be almost wholly composed of the remains of
+animals which formerly inhabited the ocean. On the other hand,
+the animal remains of the beds accompanying the coal are typically
+the remains of air-breathing, terrestrial, amphibious, or aerial
+animals, together with those which inhabit fresh or brackish
+waters. Marine fossils may be found in the Coal-measures, but
+they are invariably confined to special horizons in the strata,
+and they indicate temporary depressions of the land beneath the
+sea. Whilst the distinction here mentioned is one which cannot
+fail to strike the observer, it is convenient to consider the
+animal life of the Carboniferous as a whole: and it is simply
+necessary, in so doing, to remember that the marine fossils are
+in general derived from the inferior portion of the system;
+whilst the air-breathing, fresh-water, and brackish-water forms
+are almost exclusively derived from the superior portion of the
+same.
+</p>
+
+<p class="indent">
+The Carboniferous <i>Protozoans</i> consist mainly of
+<i>Foraminifera</i> and <i>Sponges</i>. The latter are still
+very insufficiently known, but the former are very abundant,
+and belong to very varied types. Thin slices of the limestones
+of the period, when examined by the microscope, very commonly
+exhibit the shells of <i>Foraminifera</i> in greater or less
+plenty. Some limestones, indeed, are made up of little else than
+these minute and elegant shells, often belonging to types, such
+as the Textularians and Rotalians, differing little or not at
+all from those now in existence. This is the case, for example,
+with the Carboniferous Limestone of Spergen Hill in Indiana (fig.
+114), which is almost wholly made up of the spiral shells of a
+species of <i>Endothyra</i>. In the same way, though to a less
+extent, the black Carboniferous marbles of Ireland, and the similar
+marbles of Yorkshire, the limestones of the west of England and
+of Derbyshire, and the great "Scar Limestones" of the north of
+England, contain great numbers of Foraminiferous shells; whilst
+similar organisms commonly occur in the shale-beds associated
+<a name="page_172"><span class="page">Page 172</span></a>
+with the limestones throughout the Lower Carboniferous series.
+One of the most interesting of the British Carboniferous forms
+
+<span style="float: left; margin: 4px; width: 268px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig114.jpg" width="260" height="258" alt="Fig. 114" />
+<br />
+Fig. 114.&mdash;Transparent slice of Carboniferous Limestone,
+from Spergen Hill, Indiana, U.S., showing numerous shells of
+<i>Endothyra</i> (<i>Rotalia</i>), <i>Baiteyi</i> slightly
+enlarged. (Original.)
+</span>
+
+is the <i>Saccammina</i> of Mr Henry Brady, which is sometimes
+present in considerable numbers in the limestones of Northumberland,
+Cumberland, and the west of Scotland, and which is conspicuous
+for the comparatively large size of its spheroidal or pear-shaped
+shell (reaching from an eighth to a fifth of an inch in size).
+More widely distributed are the generally spindle-shaped shells
+of <i>Fusulina</i> (fig. 115), which occur in vast numbers in
+the Carboniferous Limestone of Russia, Armenia, the Southern
+Alps, and Spain, similar forms occurring in equal profusion in
+the higher limestones which are found in the Coal-measures of the
+United States, in Ohio, Illinois, Indiana, Missouri, &amp;c. Mr
+Henry Brady, lastly, has shown that we have in the <i>Nummulina
+Pristina</i> of the Carboniferous Limestone of Namur a genuine
+
+<span style="float: left; margin: 4px; width: 289px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig115.jpg" width="281" height="76" alt="Fig. 115" />
+<br />
+Fig. 115.&mdash;<i>Fusulina cylindrica</i>, Carboniferous
+Limestone, Russia.
+</span>
+
+<i>Nummulite</i>, precursor of the great and important family
+of the Tertiary Nummulites.
+</p>
+
+<p class="indent">
+The sub-kingdom of the <i>Cœlenterates</i>, so far as certainly
+known, is represented only by <i>Corals</i>;[19] but the remains of
+these are so abundant in many of the limestones of the Carboniferous
+formation as to constitute a feature little or not at all less
+conspicuous than that afforded by the Crinoids. As is the case in
+the preceding period, the Corals belong, almost exclusively, to
+the groups of the <i>Rugosa</i> and <i>Tabulata</i>; and there is
+a general and striking resemblance and relationship between the
+coral-fauna of the Devonian as a whole, and that
+<a name="page_173"><span class="page">Page 173</span></a>
+of the Carboniferous. Nevertheless, there is an equally decided and
+striking amount of difference between these successive faunas, due
+to the fact that the great majority of the Carboniferous <i>species</i>
+are new; whilst some of the most characteristic Devonian <i>genera</i>
+have nearly or quite disappeared, and several new genera now make
+their appearance for the first time. Thus, the characteristic Devonian
+types <i>Heliophyllum, Pachyphyllum, Chonophyllum, Acervularia,
+Spongophyllum, Smithia, Endophyllum</i>, and <i>Cystiphyllum</i>,
+have now disappeared; and the great masses of <i>Favosites</i>
+which are such a striking feature in the Devonian limestones,
+are represented but by one or two degenerate and puny successors.
+On the other hand, we meet in the Carboniferous rocks not only with
+entirely new genera&mdash;such as <i>Axophyllum, Lophophyllum</i>,
+and <i>Londsdaleia</i>&mdash;but we have an enormous expansion of
+certain types which had just begun to exist in the preceding
+period. This is especially well seen in the Case of the genus
+<i>Lithostrotion</i> (fig. 116, <i>b</i>), which more than any
+other may be considered as the predominant Carboniferous group
+of Corals. All the species of <i>Lithostrotion</i> are compound,
+consisting either of bundles of loosely-approximated cylindrical
+stems, or of similar "coral-lites" closely aggregated together into
+astræiform colonies, and rendered polygonal by mutual pressure.
+This genus has a historical interest, as having been noticed as
+early as in the year 1699 by Edward Lhwyd; and it is geologically
+important from its wide distribution in the Carboniferous rocks
+of both the Old and New Worlds. Many species are known, and whole
+beds of limestone are often found to be composed of little else
+than the skeletons of these ancient corals, still standing upright
+as they grew. Hardly less characteristic of the Carboniferous
+than the above is the great group of simple "cup-corals," of
+which <i>Clisiophyllum</i> is the central type. Amongst types
+which commenced in the Silurian and Devonian, but which are still
+well represented here, may be mentioned <i>Syringopora</i> (fig.
+116, <i>e</i>), with its colonies of delicate cylindrical tubes
+united at intervals by cross-bars; <i>Zaphrentis</i> (fig. 116,
+<i>d</i>), with its cup-shaped skeleton and the well-marked
+depression (or "fossula") on one side of the calice; <i>Amplexus</i>
+(fig. 116, <i>c</i>), with its cylindrical, often irregularly
+swollen coral and short septa; <i>Cyathophyllum</i> (fig. 116,
+<i>a</i>), sometimes simple, sometimes forming great masses of
+star-like corallites; and <i>Chœtetes</i>, with its branched
+stems, and its minute, "tabulate" tubes (fig. 116, <i>f</i>).
+The above, together with other and hardly less characteristic
+forms, combine to constitute a coral-fauna which is not only in
+itself perfectly distinctive, but which is of especial interest,
+<a name="page_174"><span class="page">Page 174</span></a>
+from the fact that almost all the varied types of which it is
+composed disappeared utterly before the close of the Carboniferous
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 557px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig116.jpg" width="549" height="593" alt="Fig. 116" />
+<br />
+Fig. 116&mdash;Corals of the Carboniferous Limestone. <i>a.
+Cyathophyllum paracida</i>, showing young corallites budded forth
+from the disc of the old one; <i>a'</i>, One of the corallites of
+the same, seen in cross-section; <i>b</i>, Fragment of a mass of
+<i>Lithostrotion irregulare; b'</i>, One of the corallites of the
+same, divided transversely; <i>c</i>, Portion of the simple
+cylindrical coral of <i>Amplexus coralloides; c'</i>, Transverse
+section of the same species; <i>d, Zaphrentis vermicularis</i>,
+showing the depression or "fossula" on one side of the cup;
+<i>e</i>, Fragrent of a mass of <i>Syringopora ramulosa; f</i>,
+Fragment of <i>Cœtetes tumidus; f'</i>, Portion of the same
+of the same, enlarged. From the Carboniferous Limestone of Britain
+and Belgium. (After Thomson, De Koninck, Milne-Edwards and Haime,
+and the Author.)
+</span>
+</span>
+
+period. In the first marine sediments of a calcareous nature
+which succeeded to the Coal-measures (the magnesian limestones
+of the Permian), the great group of the <i>Rugose corals</i>,
+which flourished so largely throughout the Silurian, Devonian,
+and Carboniferous periods, is found to have all but
+<a name="page_175"><span class="page">Page 175</span></a>
+disappeared, and it is never again represented save
+sporadically and by isolated forms.
+</p>
+
+<p class="footnote">
+[Footnote 19: A singular fossil has been described by Professor
+Martin Duncan and Mr Jenkins from the Carboniferous rocks under
+the name of <i>Palœocoryne</i>, and has been referred to
+the Hydroid Zoophytes (<i>Corynida</i>). Doubt, however, has been
+thrown by other observers on the correctness of this reference.]
+</p>
+
+<p class="indent">
+Amongst the <i>Echinoderms</i>, by far the most important forms
+are the Sea-lilies and the Sea-urchins&mdash;the former from their
+great abundance, and the latter from their singular structure; but
+the little group of the "Pentremites" also requires to be noticed.
+The Sea-lilies are so abundant in the Carboniferous rocks, that it
+has been proposed to call the earlier portion of the period the
+"Age of Crinoids." Vast masses of the limestones of the period are
+"crinoidal," being more or less extensively composed of the broken
+columns, and detached plates and joints of Sea-lilies, whilst
+perfect "heads" may be exceedingly rare and difficult to procure.
+In North America the remains of Crinoids are even more abundant
+at this horizon than in Britain, and the specimens found seem
+to be commonly more perfect. The commonest of the Carboniferous
+Crinoids belong to the genera <i>Cyathocrinus, Actinocrinus,
+Platycrinus</i>, (fig. 117), <i>Poteriocrinus, Zeacrinus</i>,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 536px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig117.jpg" width="528" height="419" alt="Fig. 117" />
+<br />
+Fig. 117.&mdash;<i>Platycrinus tricontadactylus</i>, Lower
+Carboniferous. The left-hand figure shows the calyx, arms, and
+upper part of the stem; and the figure next this shows the surface
+of one of the joints of the column. The right-hand figure shows
+the proboscis. (After M'Coy.)
+</span>
+</span>
+
+and <i>Forbesiocrinus</i>. Closely allied to the Crinoids, or
+forming a kind of transition
+<a name="page_176"><span class="page">Page 176</span></a>
+between these and the Cystideans, is the
+little group of the "Pentremites," or <i>Blastoids</i> (fig. 118).
+This group is first known to have commenced its existence in
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 485px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig118.jpg" width="477" height="432" alt="Fig. 118" />
+<br />
+Fig. 118.&mdash;A, <i>Pentremites pyriformis</i>, side-view of the
+body ("calyx"); B, The same viewed from below, showing the
+arrangement of the plates; C, Body of <i>Pentremites conoideus</i>,
+viewed from above. Carboniferous.
+</span>
+</span>
+
+the Upper Silurian, and it increased considerably in numbers in
+the Devonian; but it was in the seas of the Carboniferous period
+that it attained its maximum, and no certain representative of the
+family has been detected in any later deposits. The "Pentremites"
+resemble the Crinoids in having a cup-shaped body (fig. 118, A)
+enclosed by closely-fitting calcareous plates, and supported on
+a short stem or "column," composed of numerous calcareous pieces
+flexibly articulated together. They differ from the Crinoids,
+however, in the fact that the upper surface of the body does
+not support the crown of branched feathery "arms," which are
+so characteristic of the latter. On the contrary, the summit of
+the cup is closed up in the fashion of a flower-bud, whence the
+technical name of <i>Blastoidea</i> applied to the group (Gr.
+<i>blastos</i>, a bud; <i>eidos</i>, form). From the top of the
+cup radiate five broad, transversely-striated areas (fig. 118, C),
+each with a longitudinal groove down its middle; and along each
+side of each of
+<a name="page_177"><span class="page">Page 177</span></a>
+these grooves there seems to have been attached a row of short
+jointed calcareous filaments or "pinnules."
+</p>
+
+<p class="indent">
+A few Star-fishes and Brittle-stars are known to occur in the
+Carboniferous rocks; but the only other Echinodemls of this period
+which need be noticed are the Sea-urchins (<i>Echinoids</i>).
+Detached plates and spines of these are far from rare in the
+Carboniferous deposits; but anything like perfect specimens are
+exceedingly scarce. The Carboniferous Sea-urchins agree with those
+of the present day in having the body enclosed in a shell formed
+by an enormous number of calcareous plates articulated together.
+The shell may be regarded as, typically, nearly spherical in
+shape, with the mouth in the centre of the base, and the excretory
+opening or vent at its summit. In both the ancient forms and the
+recent ones, the plates of the shell are arranged in ten zones
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 513px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig119.jpg" width="505" height="240" alt="Fig. 119" />
+<br />
+Fig. 119.&mdash;<i>Palœchinus ellipticus</i>, one of the
+Carboniferous Sea-urchins. The left-hand figure shows one of the
+"ambulacral areas" enlarged, exhibiting the perforated plates.
+The right-land figure exhibits a single plate from one of the
+"inter-ambulacral areas." (After M'Coy.)
+</span>
+</span>
+
+which generally radiate from the summit to the centre of the base. In
+five of these zones&mdash;termed the "ambulacral areas"&mdash;the
+plates are perforated by minute apertures or "pores," through which
+the animal can protrude the little water-tubes ("tube-feet") by which
+its locomotion is carried on. In the other five zones&mdash;the
+so-called "inter-ambulacral areas"&mdash;the plates are of larger
+size, and are not perforated by any apertures. In all the modern
+Sea-urchins each of these ten zones, whether perforate or imperforate,
+is composed of two rows of plates; and there are thus twenty rows of
+plates in all. In the Palæozoic Sea-urchins, on the other hand,
+the "ambulacral areas" are often like those of recent forms, in
+consisting of <i>two</i> rows of perforated plates (fig. 119); but
+the "inter-ambulacral areas" are always quite
+<a name="page_178"><span class="page">Page 178</span></a>
+peculiar in consisting each of three, four, five, or more rows of large
+imperforate plates, whilst there are sometimes four or ten rows of
+plates in the "ambulacral areas" also: so that there are many more than
+twenty rows of plates in the entire shell. Some of the Palæozoic
+Sea-urchins, also, exhibit a very peculiar singularity of structure
+which is only known to exist in a very few recently-discovered
+modern forms (viz., <i>Calveria</i> and <i>Phormosoma</i>). The
+plates of the inter-ambulacral areas, namely, overlap one another
+in an imbricating manner, so as to communicate a certain amount
+of flexibility to the shell; whereas in the ordinary living forms
+these plates are firmly articulated together by their edges,
+and the shell forms a rigid immovable box. The Carboniferous
+Sea-urchins which exhibit this extraordinary peculiarity belong
+to the genera <i>Lepidechinus</i> and <i>Lepidesthes</i>, and
+it seems tolerably certain that a similar flexibility of the
+shell existed to a less degree in the much more abundant genus
+<i>Archœocidaris</i>. The Carboniferous Sea-urchins, like
+the modern ones, possessed movable spines of greater or less
+length, articulated to the exterior of the shell; and these
+structures are of very common occurrence in a detached condition.
+The most abundant genera are <i>Archœocidaris</i> and
+<i>Palœchinus</i>; but the characteristic American forms
+belong principally to <i>Melonites, Oligoporus</i>, and
+<i>Lepidechinus</i>.
+</p>
+
+<p class="indent">
+Amongst the <i>Annelides</i> it is only necessary to notice the
+little spiral tubes of <i>Spirorbis Carbonarius</i> (fig. 120),
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 332px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig120.jpg" width="324" height="191" alt="Fig. 120" />
+<br />
+Fig. 120.&mdash;<i>Spirorbis (Microconchus) Carbonarius</i>, of
+the natural size, attached to a fossil plant, and magnified.
+Carboniferous Britain and North America. (After Dawson.)
+</span>
+</span>
+
+which are commonly found attached to the leaves or stems of the
+Coal-plants. This fact shows that though the modern species of
+<i>Spirorbis</i> are inhabitants of the sea, these old
+representatives of the genus must have been capable of living
+in the brackish waters of lagoons and estuaries.
+</p>
+
+<p class="indent">
+The <i>Crustaceans</i> of the Carboniferous rocks are numerous,
+<a name="page_179"><span class="page">Page 179</span></a>
+and belong partly to structural types with which we are already
+familiar, and partly to higher groups which come into existence
+here for the first time. The gigantic <i>Eurypterids</i> of the
+Upper Silurian and Devonian are but feebly represented, and make
+their final exit here from the scene of life. Their place, however,
+is taken by peculiar forms belonging to the allied group of the
+<i>Xiphosura</i>, represented at the present day by the King-crabs
+or "Horse-shoe Crabs" (<i>Limulus</i>). Characteristic forms of this
+group appear in the Coal-measures both of Europe and America; and
+though constituting three distinct genera (<i>Prestwichia, Belinurus</i>,
+and <i>Euproöps</i>), they are all nearly related to one
+another. The best known of them, perhaps, is the <i>Prestwichia
+rotundala</i> of Coalbrookdale, here figured (fig. 121). The ancient
+
+<span style="float: right; margin: 4px; width: 304px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig121.jpg" width="296" height="321" alt="Fig. 121" />
+<br />
+Fig. 121.&mdash;<i>Prestwichia rotundata</i>, a Limuloid Crustacean.
+Coal-measures, Britain. (After Henry Woodward.)
+</span>
+
+and formerly powerful order of the <i>Trilobites</i> also undergoes
+its final extinction here, not surviving the deposition of the
+Carboniferous Limestone series in Europe, but extending its range
+in America into the Coal-measures. All the known Carboniferous forms
+are small in size and degraded in point of structure, and they are
+referable to but three genera (<i>Phillipsia, Griffithides</i>,
+and <i>Brachymetopus</i>), belonging to a single family. The
+<i>Phillipsia seminifera</i> here figured (fig. 122, <i>a</i>)
+is a characteristic species in the Old World. The Water-fleas
+(<i>Ostracoaa</i>) are extremely abundant in the Carboniferous
+rocks, whole strata being often made up of little else than the
+little bivalved shells of these Crustaceans. Many of them are
+extremely small, averaging about the size of a millet-seed; but
+a few forms, such as <i>Entomoconchus Scouleni</i> (fig. 122,
+<i>c</i>), may attain a length of from one to three quarters of
+an inch. The old group of the <i>Phyllopods</i> is is likewise
+still represented in some abundance, partly by tailed forms of a
+shrimp-like appearance, such as <i>Dithyrocaris</i> (fig. 122,
+<i>d</i>), and partly by the curious striated <i>Estheriœ</i>
+and their allies, which present a curious
+<a name="page_180"><span class="page">Page 180</span></a>
+resemblance to the true Bivalve Molluscs (fig. 122, <i>b</i>).
+Lastly, we meet for the first time in the Carboniferous rocks
+with the remains of the highest of all the groups of
+<i>Crustaceans</i>&mdash;namely, the so-called "Decapods," in
+which there are five pairs of walking-limbs, and the hinder end
+of the body ("abdomen") is composed of separate rings, whilst
+the anterior end is covered by a head-shield or "carapace." All
+the Carboniferous Decapods hitherto discovered resemble the
+existing Lobsters, Prawns, and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 531px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig122.jpg" width="523" height="455" alt="Fig. 122" />
+<br />
+Fig. 122.&mdash;Crustaceans of the Carboniferous Rocks. <i>a,
+Phillipsia seminifera</i>, of the natural size&mdash;Mountain
+Limestone, Europe; <i>b</i>, One valve of the shell of <i>Estheria
+tenella</i>, of the natural size and enlarged&mdash;Coal-measures,
+Europe; <i>c</i>, Bivalved shell of <i>Entomoconchus Scouleri</i>,
+of the natural size&mdash;Mountain Limestone, Europe; <i>d,
+Dithyrocaris Scouleri</i>, reduced in size&mdash;Mountain Limestone,
+Ireland; <i>e, Palœocaris typus</i>, slightly
+enlarged&mdash;Coal-measures, North America; <i>f,
+Anthrapalœmon gracilis</i>, of the natural
+size&mdash;Coal-measures, North America. (After De Koninck, M'Coy,
+Rupert Jones, and Meek and Worthen.)
+</span>
+</span>
+
+Shrimps (the <i>Macrura</i>), in having a long and well-developed
+abdomen terminated by an expanded tail-fin. The <i>Palœocaris
+typus</i> (fig. 122, <i>e</i>) and the <i>Anthrapalœmon
+gracilis</i> (fig. 122, <i>f</i>), from the Coal-measures of
+Illinois, are two of the best understood and most perfectly
+preserved of the few known representatives of the "Long-tailed"
+Decapods in the Carboniferous series. The group of the Crabs or
+"Short-tailed"
+<a name="page_181"><span class="page">Page 181</span></a>
+Decapods (<i>Brachyura</i>), in which the abdomen is short, not
+terminated by a tail-fin, and tucked away out of sight beneath
+the body, is at present not known to be represented at all in
+the Carboniferous deposits.
+</p>
+
+<p class="indent">
+In addition to the water-inhabiting group of the Crustaceans, we
+find the articulate animals to be represented by members belonging
+to the air-breathing classes of the <i>Arachnida, Myriapoda</i>,
+and <i>Insecta</i>. The remains of these, as might have been
+expected, are not known to occur in the marine limestones of the
+Carboniferous series, but are exclusively found in beds associated
+with the Coal, which have been deposited in lagoons, estuaries, or
+marshes, in the immediate vicinity of the land, and which actually
+represent an old land-surface. The <i>Arachnids</i> are at present
+the oldest known of their class, and are represented both by true
+Spiders and Scorpions. Remains of the latter (fig. 123) have been
+found both in the Old and New Worlds, and indicate the existence
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig123.jpg" width="523" height="447" alt="Fig. 123" />
+<br />
+Fig. 123.&mdash;<i>Cyclophthalmus senior</i>. A fossil Scorpion
+from the Coal-measures of Bohemia.
+</span>
+</span>
+
+in the Carboniferous period of Scorpions differing but very little
+from existing forms. The group of the <i>Myriapoda</i>, including
+the recent Centipedes and Galley-worms, is likewise represented
+in the Carboniferous strata,
+<a name="page_182"><span class="page">Page 182</span></a>
+but by forms in many respects
+very unlike any that are known to exist at the present day.
+The most interesting of these were obtained by Principal Dawson,
+along with the bones of Amphibians and the shells of Land-snails,
+in the sediment filling the hollow trunks of <i>Sigillaria</i>,
+and they belong to the genera <i>Xylobius</i> (fig. 124) and
+Archiulus. Lastly, the true <i>insects</i> are represented by
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 296px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig124.jpg" width="288" height="237" alt="Fig. 124" />
+<br />
+Fig. 124.&mdash;<i>Xylobius Sigillariœ</i>, a Carboniferous
+Myriapod. <i>a</i>, A specimen, of the natural size; <i>b</i>,
+Anterior portion of the same, enlarged; <i>c</i>, Posterior
+portion, enlarged. From the Coal-measures of Nova Scotia.
+(After Dawson.)
+</span>
+</span>
+
+various forms of Beetles (<i>Coleoptera</i>), <i>Orthoptera</i>
+(such as Cockroaches), and <i>Neuropterous</i> insects resembling
+those which we have seen to have existed towards the close of
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 613px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig125.jpg" width="605" height="316" alt="Fig. 125" />
+<br />
+Fig. 125&mdash;<i>Haplophlebium Barnesi</i>, a Carboniferous
+insect, from the Coal-meastures of Nova Scotia. (After Dawson.)
+</span>
+</span>
+
+the Devonian period. One of the most remarkable of the latter
+is a huge May-fly (<i>Haplophlebium Barnesi</i>, fig. 125), with
+<a name="page_183"><span class="page">Page 183</span></a>
+netted wings attaining an expanse of fully seven inches, and
+therefore much exceeding any existing Ephemerid in point of size.
+</p>
+
+<p class="indent">
+The lower groups of the <i>Mollusca</i> are abundantly represented
+in the marine strata of the Carboniferous series by <i>Polyzoans</i>
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 487px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig126.jpg" width="479" height="570" alt="Fig. 126" />
+<br />
+Fig. 126.&mdash;Carboniferous <i>Polyzoa</i>. <i>a</i>, Fragment of
+<i>Polypora dendroides</i>, of the natural size, Ireland; <i>a'</i>
+Small portion of the same, enlarged to show the cells; <i>b,
+Glauconome pulcherrima</i>, a fragment, of the natural size,
+Ireland; <i>b'</i>, Portion of the same, enlarged; <i>c</i>, The
+central screw-like axis of <i>Archimedes Wortheni</i>, of the
+natural size&mdash;Carboniferous, America; <i>c'</i>, Portion of
+the exterior of the frond of the same, enlarged; <i>c''</i>,
+Portion of the interior of the frond of the same showing the
+mouths of the cells, enlarged. (After M'Coy and Hall.)]
+</span>
+</span>
+
+and <i>Brachiopods</i>. Amongst the former, although a variety
+of other types are known, the majority still belong to the old
+group of the "Lace-corals" (<i>Fenestellidœ</i>), some of
+the characteristic forms of which are here figured (fig. 126).
+The graceful
+<a name="page_184"><span class="page">Page 184</span></a>
+netted fronds of <i>Fenestella,
+Retepora</i>, and <i>Polypora</i> (fig. 126, <i>a</i>) are highly
+characteristic, as are the slender toothed branches of
+<i>Glauconome</i> (fig. 126, <i>b</i>). A more singular form,
+however, is the curious <i>Archimedes</i> (fig. 126, <i>c</i>),
+which is so characteristic of the Carboniferous formation of
+North America. In this remarkable type, the colony consists of
+a succession of funnel-shaped fronds, essentially similar to
+<i>Fenestella</i> in their structure, springing in a continuous
+spiral from a strong screw-like vertical axis. The outside of
+the fronds is simply striated; but the branches exhibit on the
+interior the mouths of the little cells in which the
+semi-independent beings composing the colony originally lived.
+</p>
+
+<p class="indent">
+The <i>Brachiopods</i> are extremely abundant, and for the most
+part belong to types which are exclusively or principally
+Palæozoic in their range. The old genera <i>Strophomena,
+Orthis</i> (fig. 127, <i>c</i>), <i>Athyris</i> (fig. 127,
+<i>e</i>), <i>Rhynchonella</i> (fig. 127, <i>g</i>), and
+<i>Spirifera</i> (fig. 127, <i>h</i>), are still well
+represented&mdash;the latter, in particular, existing under
+numerous specific forms, conspicuous by their abundance and
+sometimes by their size. Along with these ancient groups, we
+have representatives&mdash;for the first time in any plenty&mdash;of
+the great genus <i>Terebratula</i> (fig. 127, <i>d</i>), which
+underwent a great expansion during later periods, and still exists
+at the present day. The most characteristic Carboniferous
+Brachiopods, however, belong to the family of the
+<i>Productidœ</i>, of which the principal genus is
+<i>Producta</i> itself. This family commenced its existence in
+the Upper Silurian with the genus <i>Chonetes</i>, distinguished
+by its spinose hinge-margin. This genus lived through the
+Devonian, and flourished in the Carboniferous (fig. 127,
+<i>f</i>). The genus <i>Producta</i> itself, represented in the
+Devonian by the nearly allied <i>Productella</i>, appeared first
+in the Carboniferous, at any rate, in force, and survived into
+the Permian; but no member of this extensive family has yet been
+shown to have over-lived the Palæozoic period. The
+<i>Productœ</i> of the Carboniferous are not only
+exceedingly abundant, but they have in many instances a most
+extensive geographical range, and some species attain what may
+fairly be considered-gigantic dimensions. The shell (fig. 127,
+<i>a</i> and <i>b</i>) is generally more or less semicircular,
+with a straight hinge-margin, and having its lateral angles
+produced into larger or smaller ears (hence its generic
+name&mdash;"<i>cochlea producta</i>"). One valve (the ventral) is
+usually strongly convex, whilst the other (the dorsal) is flat
+or concave, the surface of both being adorned with radiating
+ribs, and with hollow tubular spines, often of great length.
+The valves are not locked together by teeth, and there is no
+sign in the
+<a name="page_185"><span class="page">Page 185</span></a>
+fully-grown shell of an opening in or between the valves for
+the emission of a muscular stalk for the attachment of the shell
+to foreign objects. It is probable, therefore, that the
+<i>Productœ</i>, unlike the ordinary Lamp-shells, lived
+an independent existence, their long spines apparently serving
+to anchor them firmly in the mud or ooze of the sea-bottom; but
+Mr Robert Etheridge, jun.; has recently shown that in one species
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 498px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig127.jpg" width="490" height="488" alt="Fig. 127" />
+<br />
+Fig. 127.&mdash;Carboniferous <i>Braciopoda. a, Producta
+semireticulata</i>, showing the slightly concave dorsal valve;
+<i>a'</i> Side view of the same, showing the convex ventral valve;
+<i>b, Producta longispina; c, Orthis resupinata; d, Terebratula
+hastata; e, Athyris subtilita; f, Chonetes Hardrensis; g,
+Rhynchonella pleurodon; h, Spirifera trigonalis</i>. Most of
+these forms are widely distributed in the Carboniferous Limestone
+of Britain, Europe, America, &amp;c. All the figures are of the
+natural size. (After Davidson, De Koninck, and Meek.)
+</span>
+</span>
+
+the spines were actually employed as organs of adhesion, whereby
+the shell was permanently attached to some extraneous object,
+such as the stem of a Crinoid. The two species here figured are
+interesting for their extraordinarily extensive geographical
+range&mdash;<i>Producta semireticulata</i> (fig. 127, <i>a</i>)
+being found in the Carboniferous rocks of Britain, the continent
+of Europe, Central Asia, China, India, Australia, Spitzbergen,
+and North
+<a name="page_186"><span class="page">Page 186</span></a>
+and South America; whilst <i>P. Longispina</i> (fig. 127,
+<i>b</i>) has a distribution little if at all less wide.
+</p>
+
+<p class="indent">
+The higher <i>Mollusca</i> are abundantly represented in the
+Carboniferous rocks by Bivalves (<i>Lamellibranchs</i>), Univalves
+(<i>Gasteropoda</i>), Winged-snails (<i>Pteropoda</i>), and
+<i>Cephalopods</i>. Amongst the Bivalves we may note the great
+abundance of Scallops (<i>Aviculopecten</i> and other allied forms),
+together with numerous other types&mdash;some of ancient origin,
+others represented here for the first time. Amongst the Gasteropods,
+we find the characteristically Palæozoic genera
+<i>Macrocheilus</i> and <i>Loxonema</i>, the almost exclusively
+Palæozoic <i>Euomphalus</i>, and the persistent, genus
+<i>Pleurotomaria</i>; whilst the free-swimming Univalves
+(<i>Heteropoda</i>)are represented by <i>Bellerophon</i> and
+<i>Porcellia</i>, and the <i>Pteropoda</i> by the old genus
+<i>Conularia</i>. With regard to the Carboniferous Univalves,
+it is also of interest to note here the first appearance of true
+air-breathing or terrestrial Molluscs, as discovered by
+Dawson and Bradley in the Coal-measures of Nova Scotia and Illinois.
+Some of these (<i>Conulus priscus</i>) are true Land-snails,
+resembling the existing <i>Zonites</i>; whilst others (<i>Pupa
+vetusta</i>, fig. 128) appear to be generically inseparable from
+
+<span style="float: left; margin: 4px; width: 217px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig128.jpg" width="209" height="324" alt="Fig. 128" />
+<br />
+Fig. 128.&mdash;<i>Pupa (Dendropupa) vetusta</i>, a Carboniferous
+Land-snail from the Coal-measures of Nova Scotia. <i>a</i>, The
+shell, of the natural size; <i>b</i>, The same, magnified;
+<i>c</i>, Apex of the shell, enlarged; <i>d</i>, Portion of the
+surface, enlarged. (After Dawson.)
+</span>
+
+the "Chrysalis-shells" (<i>Pupa</i>) of the present day. All the
+known forms&mdash;three in number&mdash;are of small size, and appear
+to have been local in their distribution or in their preservation.
+More important, however, than any of the preceding, are the
+<i>Cephalopoda</i>, represented, as before, exclusively by the
+chambered shells of the Tetrabranchiates. The older and simpler
+type of these, with simple plain septa, and mostly a central
+siphuncle, is represented by the straight conical shells of the
+ancient genus Orthoceras, and the bow-shaped shells of the equally
+ancient <i>Cyrtoceras</i>&mdash;some of the former attaining a
+great size. The spirally-curved discoidal shells of the persistent
+genus <i>Nautilus</i> are also not unknown, and some of these
+likewise exhibit very considerable dimensions. Lastly, the more
+complex family of the <i>Ammonitidœ</i>,
+<a name="page_187"><span class="page">Page 187</span></a>
+with lobed or angulated septa, and a dorsally-placed
+siphuncle (situated on the convex side of the curved shells), now
+for the first time commences to acquire a considerable prominence.
+The principal representative of this group is the genus
+<i>Goniatites</i> (fig. 129), which
+commenced its existence in the Upper Silurian, is well represented
+in the Devonian, and attains its maximum here. In this genus,
+the shell is spirally curved, the septa are strongly lobed or
+angulated, though not elaborately frilled as in the Ammonites,
+and the siphuncle is dorsal. In addition to <i>Goniatites</i>,
+the shells of true <i>Ammonites</i>, so characteristic of the
+Secondary period, have been described by Dr Waagen as occurring
+in the Carboniferous rocks of India.
+</p>
+
+<div class="center">
+<table border="0" width="555">
+<tr><td>
+<img src="images/fig129.jpg" width="551" height="590" alt="Fig. 129" />
+</td></tr>
+<tr><td class="center"><span class="image">
+Fig. 129.&mdash;<i>Goniatites (Aganides) Fossœ</i>.
+Carboniferous Limestone.
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+Coming finally to the <i>Vertebrata</i>, we have in the first
+place to very briefly consider the Carboniferous <i>fishes</i>.
+These are numerous; but, with the exception of the still dubious
+"Conodonts," belong wholly to the groups of the <i>Ganoids</i> and
+the <i>Placoids</i> (including under the former head remains which
+perhaps are truly referable to the group of the <i>Dipnoi</i> or
+Mud-fishes). Amongst the <i>Ganoids</i>, the singular buckler-headed
+fishes of the Upper Silurian and Devonian (<i>Cephalaspidœ</i>)
+<a name="page_188"><span class="page">Page 188</span></a>
+have apparently disappeared; and the principal
+types of the Carboniferous belong to the groups respectively
+represented at the present day by the Gar pike (<i>Lepidosteus</i>)
+of the North American lakes, and the <i>Polypterus</i> of the rivers
+of Africa. Of the former, the genera <i>Palœoniscus</i> and
+<i>Amblypterus</i> (fig. 130), with their small rhomboidal and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 518px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig130.jpg" width="510" height="225" alt="Fig. 130" />
+<br />
+Fig. 130.&mdash;<i>Amblypterus macropterus</i>.
+</span>
+</span>
+
+enamelled scales, and their strongly unsymmetrical tails, are
+perhaps the most abundant. Of the latter, the most important are
+species belonging to the genera <i>Megalichthys</i> and
+<i>Rhizodus</i>, comprising large fishes, with rhomboidal scales,
+unsymmetrical ("heterocercal") tails, and powerful conical teeth.
+These fishes are sometimes said to be "sauroid," from their
+presenting some Reptilian features in their organisation, and
+they must have been the scourges of the Carboniferous seas. The
+remains of <i>Placoid</i> fishes in the Carboniferous strata are
+very numerous, but consist wholly of teeth and fin-spines,
+referable to forms more or less closely allied to our existing
+Port Jackson Sharks, Dog-fishes, and Rays. The teeth are of very
+various shapes and sizes,&mdash;some with sharp, cutting edges
+(<i>Petalodus, Cladodus</i>, &amp;c.); others in the form of
+broad crushing plates, adapted, like the teeth of the existing
+Port Jackson Shark (<i>Cestracion Philippi</i>), for breaking
+down the hard shells of Molluscs and Crustaceans. Amongst the
+many kinds of these latter, the teeth of <i>Psammodus</i> and
+<i>Cochliodus</i> (fig. 131) may be mentioned as specially
+characteristic. The fin-spines are mostly similar to those so
+common in the Devonian deposits, consisting of hollow defensive
+spines implanted in front of the pectoral or other fins, usually
+slightly curved, often superficially ribbed or sculptured, and
+not uncommonly serrated or toothed. The genera <i>Ctenacanthus,
+Gyracanthus, Homacanthus</i>, &amp;c., have been founded for the
+reception of these defensive weapons, some of which indicate
+fishes of great size and predaceous habits.
+</p>
+
+<p class="indent">
+<a name="page_189"><span class="page">Page 189</span></a>
+In the Devonian rocks we meet with no
+other remains of Vertebrated animals save fishes only; but the
+Carboniferous deposits have yielded remains of the higher group
+
+<span style="float: right; margin: 4px; width: 263px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig131.jpg" width="255" height="179" alt="Fig. 131" />
+<br />
+Fig. 131.&mdash;Teeth of <i>Cochliodus contortus</i>.
+Carboniferous Limestone, Britain.
+</span>
+
+of the <i>Amphibians</i>. This class, comprising our existing
+Frogs, Toads, and Newts, stands to some extent in a position
+midway between the class of the fishes and that of the true
+reptiles, being distinguished from the latter by the fact
+that its members invariably  possess gills in their early
+condition, if not throughout life; whilst they are separated
+from the former by always possessing true lungs when adult, and
+by the fact that the limbs (when present at all) are never in
+the form of fins. The Amphibians, therefore, are all
+water-breathers when young, and have respiratory organs adapted
+for an aquatic mode of life; whereas, when grown up, they
+develop lungs, and with these the capacity for breathing air
+directly. Some of them, like the Frogs and Newts, lose their
+gills altogether on attaining the adult condition; but others,
+such as the living <i>Proteus</i> and <i>Menobranchus</i>, retain
+their gills even after acquiring their lungs, and are thus fitted
+indifferently for an aquatic or terrestrial existence. The name
+of "Amphibia," though applied to the whole class, is thus not
+precisely appropriate except to these last-mentioned forms
+(Gr. <i>amphi</i>, both; <i>bios</i>, life). The Amphibians also
+differ amongst themselves according as to whether they keep
+permanently the long tail which they all possess when young
+(as do the Newts and Salamanders), or lose this appendage when
+grown up (as do the Frogs and Toads). Most of them have naked
+skins, but a few living and many extinct forms have hard
+structures in the shape of scales developed in the integument.
+All of them have well-ossified skeletons, though some fossil
+types are partially deficient in this respect; and all of them
+which possess limbs at all have these appendages supported by
+bones essentially similar to those found in the limbs of the
+higher Vertebrates. All the Carboniferous Amphibians belong to
+a group which has now wholly passed away&mdash;namely, that of
+the <i>Labyrinthodonts</i>. In the marine strata which form the
+base of the Carboniferous series these creatures have only been
+recognised by their curious hand-shaped footprints, similar
+<a name="page_190"><span class="page">Page 190</span></a>
+in character to those which occur in the
+Triassic rocks, and which will be subsequently spoken of under
+the name of <i>Cheirotherium</i>. In the Coal-measures of
+Britain, the continent of Europe, and North America, however,
+many bones of these animals have been found, and we are now
+tolerably well acquainted with a considerable number of forms.
+All of them seem to have belonged to the division of Amphibians
+in which the long tail of the young is permanently retained; and
+there is evidence that some of them kept the gills also throughout
+life. The skull is of the characteristic Amphibian type (fig. 132,
+<i>a</i>), with two occipital condyles, and having its surface
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 531px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig132.jpg" width="523" height="436" alt="Fig. 132" />
+<br />
+Fig. 132.&mdash;<i>a</i>, Upper surface of the skull of
+<i>Anthracosaurus Russelli</i>, one-sixth of the natural size:
+<i>b</i>, Part of one of the teeth cut across, and highly magnified
+to show the characteristic labyrinthine structure; <i>c</i>, One
+of the integumentary shields or scales, one-half of the natural
+size. Coal-measures, Northumberland. (After Atthey.)
+</span>
+</span>
+
+singularly pitted and sculptured; and the vertebræ are
+hollowed out at both ends. The lower surface of the body was
+defended by an armour of singular integumentary shields or scales
+(fig. 132, <i>c</i>); and an extremely characteristic feature
+(from which the entire group derives its name) is, that the walls
+of the teeth are deeply folded, so as to give rise to an
+extraordinary "labyrinthine" pattern when they are cut across
+(fig. 132, <i>b</i>). Many of the Carboniferous Labyrinthodonts
+are of no great size, some of them
+<a name="page_191"><span class="page">Page 191</span></a>
+very small, but others attain comparatively gigantic dimensions,
+though all fall short in this respect of the huge examples of
+this group which occur in the Trias. One of the largest, and
+at the same time most characteristic, forms of the Carboniferous
+series, is the genus <i>Anthracosaurus</i>, the skull of which
+is here figured.
+</p>
+
+<p class="indent">
+No remains of true Reptiles, Birds, or Quadrupeds have as yet
+been certainly detected in the Carboniferous deposits in any part
+of the world. It should, however, be mentioned, that Professor
+Marsh, one of the highest authorities on the subject, has described
+from the Coal-formation of Nova Scotia certain vertebræ which
+he believes to have belonged to a marine reptile (<i>Eosaurus
+Acadianus</i>), allied to the great <i>Ichthyosauri</i> of the
+Lias. Up to this time no confirmation of this determination has
+been obtained by the discovery of other and more unquestionable
+remains, and it therefore remains doubtful whether these bones of
+<i>Eosaurus</i> may not really belong to large Labyrinthodonts.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following list contains some of the more important of the
+original sources of information to which the student of Carboniferous
+rocks and fossils may refer:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Geology of Yorkshire,' vol. ii.; 'The Mountain Limestone
+  District.' John Phillips.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Siluria.' Sir Roderick Murchison.</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Memoirs of the Geological Survey of Great Britain and
+  Ireland.'</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>'Geological Report on Londonderry,' &amp;c. Portlock.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>'Acadian Geology.' Dawson.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>'Geology of Iowa,' vol. i. James Hall.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>'Reports of the Geological Survey of Illinois' (Geology and
+  Palæontology). Meek, Worthen, &amp;c.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>'Reports of the Geological Survey of Ohio' (Geology and
+  Palæontology). Newberry, Cope, Meek, Hall, &amp;c.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>'Description des Animaux fossiles qui se trouvent dans le
+  Terrain Carbonifère de la Belgique,' 1843; with subsequent
+  monographs on the genera <i>Productus</i> and <i>Chonetes</i>,
+  on <i>Crinoids</i>, on <i>Corals</i>, &amp;c. De Koninck.</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Synopsis of the Carboniferous Fossils of Ireland.'
+  M'Coy.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'British Palæozoic Fossils.' M'Coy.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>'Figures of Characteristic British Fossils.' Baily.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>'Catalogue of British Fossils.' Morris.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>'Monograph of the Carboniferous Brachiopoda of Britain'
+  (Palæontographical Society). Davidson.</td></tr>
+<tr><td class="right" valign="top">(15)</td>
+ <td>'Monograph of the British Carboniferous Corals'
+  (Palæontographical Society). Milne-Edwards and
+  Haime.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Monograph of the Carboniferous Bivalve Entomostraca of
+  Britain' (Palæontographical Society). Rupert Jones,
+  Kirkby, and George S. Brady.</td></tr>
+<tr><td class="right" valign="top">
+<a name="page_192"><span class="page">Page 192</span></a>
+  (17)</td>
+ <td>'Monograph of the Carboniferous Foraminifera of Britain'
+  (Palæontographical Society). H. B. Brady.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>"On the Carboniferous Fossils of the West of
+  Scotland"&mdash;'Trans. Geol. Soc.,' of Glasgow, vol. iii.,
+  Supplement. Young and Armstrong.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>'Poissons Fossiles.' Agassiz.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>"Report on the Labyrinthodonts of the
+  Coal-measures"&mdash;'British Association Report,' 1873. L. C.
+  Miall.</td></tr>
+<tr><td class="right" valign="top">(21)</td>
+ <td>'Introduction to the Study of Palæontological
+  Botany.' John Hutton Balfour.</td></tr>
+<tr><td class="right" valign="top">(22)</td>
+ <td>'Traité de Paléontologie
+  Végétale.' Schimper.</td></tr>
+<tr><td class="right" valign="top">(23)</td>
+ <td>'Fossil Flora.' Lindley and Hutton.</td></tr>
+<tr><td class="right" valign="top">(24)</td>
+ <td>'Histoire des Végétaux Fossiles.'
+  Brongniart.</td></tr>
+<tr><td class="right" valign="top">(25)</td>
+ <td>'On Calamites and Calamodendron' (Monographs of the
+  Palæontographical Society). Binney.</td></tr>
+<tr><td class="right" valign="top">(26)</td>
+ <td>'On the Structure of Fossil Plants found in the
+  Carboniferous Strata' (Palæontographical Society).
+  Binney.</td></tr>
+</table>
+
+<p class="indent">
+Also numerous memoirs by Huxley, Davidson, Martin Duncan, Professor
+Young, John Young, R. Etheridge, jun., Baily, Carruthers, Dawson,
+Binney, Williamson, Hooker, Jukes, Geikie, Rupert Jones, Salter,
+and many other British and foreign observers.
+</p>
+
+<h3>CHAPTER XIV.</h3>
+
+<p class="subtitle">
+THE PERMIAN PERIOD.
+</p>
+
+<p class="indent">
+The Permian formation closes the long series of the Palæozoic
+deposits, and may in some respects be considered as a kind of
+appendix to the Carboniferous system, to which it cannot be compared
+in importance, either as regards the actual bulk of its sediments
+or the interest and variety of its life-record. Consisting, as it
+does, largely of red rocks&mdash;sandstones and marls&mdash;for the
+most part singularly destitute of organic remains, the Permian
+rocks have been regarded as a lacustrine or fluviatile deposit;
+but the presence of well-developed limestones with indubitable
+marine remains entirely negatives this view. It is, however,
+not improbable that we are presented in the Permian formation,
+as known to us at present, with a series of sediments laid down
+in inland seas of great extent, due to the subsidence over large
+areas of the vast land-surfaces of the Coal-measures. This view,
+at any rate, would explain some of the more puzzling physical
+characters of the formation, and would not be definitely negatived
+by any of its fossils.
+</p>
+
+<p class="indent">
+A large portion of the Permian series, as already remarked, consists
+of sandstones and marls, deeply reddened by peroxide
+<a name="page_193"><span class="page">Page 193</span></a>
+of iron, and often accompanied by beds of gypsum or deposits
+of salt. In strata of this nature few or no fossils are found; but
+their shallow-water origin is sufficiently proved by the presence of
+the footprints of terrestrial animals, accompanied in some cases by
+well-defined "ripple-marks." Along with these are occasionally found
+massive breccias, holding larger or smaller blocks derived from the
+older formations; and these have been supposed to represent an old
+"boulder-clay," and thus to indicate the prevalence of an arctic
+climate. Beds of this nature must also have been deposited in
+shallow water. In all regions, however, where the Permian formation
+is well developed, one of its most characteristic members is a
+Magnesian limestone, often highly and fantastically concretionary,
+but containing numerous remains of genuine marine animals, and
+clearly indicating that it was deposited beneath a moderate depth
+of salt water.
+</p>
+
+<p class="indent">
+It is not necessary to consider here whether this formation can
+be retained as a distinct division of the geological series. The
+name of <i>Permian</i> was given to it by Sir Roderick Murchison,
+from the province of Perm in Russia, where rocks of this age are
+extensively developed. Formerly these rocks were grouped with
+the succeeding formation of the Trias under the common name of
+"New Red Sandstone." This name was given them because they contain
+a good deal of red sandstone, and because they are superior to the
+Carboniferous rocks, while the Old Red Sandstone is inferior.
+Nowadays, however, the term "New Red Sandstone" is rarely employed,
+unless it be for red sandstones and associated rocks, which are
+seen to overlie the Coal-measures, but which contain no fossils by
+which their exact age may be made out. Under these circumstances,
+it is sometimes convenient to employ the term "New Red Sandstone."
+The New Red, however, of the older geologists, is now broken up
+into the two formations of the Permian and Triassic rocks&mdash;the
+former being usually considered as the top of the Palæozoic
+series, and the latter constituting the base of the Mesozoic.
+</p>
+
+<p class="indent">
+In many instances, the Permian rocks are seen to repose unconformably
+upon the underlying Carboniferous, from which they can in addition
+be readily separated by their lithological characters. In other
+instances, however, the Coal-measures terminate upwards in red
+rocks, not distinguishable by their mineral characters from the
+Permian; and in other cases no physical discordance between the
+Carboniferous and Permian strata can be detected. As a general
+rule, also, the Permian rocks appear to pass upwards conformably
+into the
+<a name="page_194"><span class="page">Page 194</span></a>
+Trias. The division, therefore,
+between the Permian and Triassic rocks, and consequently between
+the Palæozoic and Mesozoic series, is not founded upon any
+conspicuous or universal physical break, but upon the difference
+in life which is observed in comparing the marine animals of the
+Carboniferous and Permian with those of the Trias. It is to be
+observed, however, that this difference can be solely due to the
+fact that the Magnesian Limestone of the Permian series presents
+us with only a small, and not a typical, portion of the marine
+deposits which must have been accumulated in some area at present
+unknown to us during the period which elapsed between the
+formation of the great marine limestones of the Lower
+Carboniferous and the open-sea and likewise calcareous sediments
+of the Middle Trias.
+</p>
+
+<p class="indent">
+The Permian rocks exhibit their most typical features in Russia
+and Germany, though they are very well developed in parts of
+Britain, and they occur in North America. When well developed,
+they exhibit three main divisions: a lower set of sandstones,
+a middle group, generally calcareous, and an upper series of
+sandstones, constituting respectively the Lower, Middle, and Upper
+Permians.
+</p>
+
+<p class="indent">
+In Russia, Germany, and Britain, the Permian rocks consist of
+the following members:&mdash;
+</p>
+
+<p class="indent">
+1. The <i>Lower Permians</i>, consisting mainly of a great series
+of sandstones, of different colours, but usually red. The base
+of this series is often constituted by massive breccias with
+included fragments of the older rocks, upon which they may happen
+to repose; and similar breccias sometimes occur in the upper
+portion of the series as well. The thickness of this group varies
+a good deal, but may amount to 3000 or 4000 feet.
+</p>
+
+<p class="indent">
+2. The <i>Middle Permians</i>, consisting, in their typical
+development, of laminated marls, or "marl-slate," surmounted
+by beds of magnesian limestone (the "Zechstein" of the German
+geologists). Sometimes the limestones are degenerate or wholly
+deficient, and the series may consist of sandy shales and gypsiferous
+clays. The magnesian limestone, however, of the Middle Permians
+is, as a rule, so well marked a feature that it was long spoken
+of as <i>the</i> Magnesian Limestone.
+</p>
+
+<p class="indent">
+3. The <i>Upper Permians</i>, consisting of a series of sandstones
+and shales, or of red or mottled marls, often gypsiferous, and
+sometimes including beds of limestone.
+</p>
+
+<p class="indent">
+In North America, the Permian rocks appear to be confined to the
+region west of the Mississippi, being especially well developed
+in Kansas. Their exact limits have not as yet been
+<a name="page_195"><span class="page">Page 195</span></a>
+made out, and their total thickness is not more than
+a few hundred feet. They consist of sandstones, conglomerates,
+limestones, marls, and beds of gypsum.
+</p>
+
+<p class="indent">
+The following diagrammatic section shows the general sequence of
+the Permian deposits in the north of England, where the series
+is extensively developed (fig. 133):&mdash;
+</p>
+
+<div class="center">
+<table border="0" width="527">
+<tr><td class="center"><span class="image">
+GENERALISED SECTION OF THE PERMIAN ROCKS IN THE NORTH OF ENGLAND.
+</span></td></tr>
+<tr><td class="center"><span class="image">
+Fig. 133.
+</span></td></tr>
+<tr><td>
+<img src="images/fig133.jpg" width="523" height="600" alt="Fig. 133" />
+</td></tr>
+</table>
+</div>
+
+<p class="indent">
+The record of the <i>life</i> of the Permian period is but a scanty
+one, owing doubtless to the special peculiarities of such of the
+<a name="page_196"><span class="page">Page 196</span></a>
+deposits of this age with which we are as yet
+acquainted. Red rocks are, as a general rule, more or less completely
+unfossiliferous, and sediments of this nature are highly
+characteristic of the Permian. Similarly, magnesian limestones are
+rarely as highly charged with organic remains as is the case with
+normal calcareous deposits, especially when they have been subjected
+to concretionary action, as is observable to such a marked extent in
+the Permian limestones. Nevertheless, much interest is attached to
+the organic remains, as marking a kind of transition-period between
+the Palæozoic and Mesozoic epochs.
+</p>
+
+<p class="indent">
+The <i>plants</i> of the Permian period, as a whole, have a
+distinctly Palæozoic aspect, and are far more nearly allied to
+those of the Coal-measures than they are to those of the earlier
+Secondary rocks; though the Permian <i>species</i> are mostly
+distinct from the Carboniferous, and there are some new genera.
+Thus, we find species of <i>Lepidodendron, Calamites, Equisetites,
+Asterophyllites, Annularia</i>, and other highly characteristic
+Carboniferous genera. On the other hand, the <i>Sigillariods</i>
+of the Coal seem to have finally disappeared at the close of the
+Carboniferous period. Ferns are abundant in the Permian rocks,
+and belong for the most part to the well-known Carboniferous
+genera <i>Alethopteris, Neuropteris, Sphenopteris</i>, and
+<i>Pecopteris</i>. There are also Tree-ferns referable to the
+ancient genus <i>Psaronius</i>. The <i>Conifers</i> of the Permian
+period are numerous, and belong in part to Carboniferous genera.
+A characteristic genus, however, is <i>Walchia</i> (fig. 134),
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 493px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig134.jpg" width="485" height="240" alt="Fig. 134" />
+<br />
+Fig. 134.&mdash;<i>Walchia piniformis</i>, from the Permian of
+Saxony, <i>a</i>, Branch; <i>b</i>, Twig, (After Gutbier.)
+</span>
+</span>
+
+distinguished by its lax short leaves. This genus, though not
+exclusively Permian, is mainly so, the best-known species being
+the <i>W. Piniformis</i>. Here, also, we meet with Conifers which
+produce true cones, and which differ, therefore, in an important
+degree from the
+<a name="page_197"><span class="page">Page 197</span></a>
+Taxoid Conifers of the
+Coal-measures. Besides <i>Walchia</i>, a characteristic form of
+these is the <i>Ullmania selaginoides</i>, which occurs in the
+Magnesian Limestone of Durham, the Middle Permian of Westmorland,
+and the "Kupfer-schiefer" of Germany. The group of the
+<i>Cycads</i>, which we shall subsequently find to be so
+characteristic of the vegetation of the Secondary period, is, on
+the other hand, only doubtfully represented in the Permian
+deposits by the singular genus <i>Nœggerathia</i>.
+</p>
+
+<p class="indent">
+The <i>Protozoans</i> of the Permian rocks are few in number, and
+for the most part imperfectly known. A few <i>Foraminifera</i>
+have been obtained from the Magnesian Limestone of England, and
+the same formation has yielded some ill-understood Sponges. It
+does not seem, however, altogether impossible that some of the
+singular "concretions" of this formation may ultimately prove to
+have an organic structure, though others would appear to be clearly
+of purely inorganic origin. From the Permian of Saxony, Professor
+Geinitz has described two species of <i>Spongillopsis</i>, which
+he believes to be most nearly allied to the existing fresh-water
+Sponges (<i>Spongilla</i>). This observation has an interest as
+bearing upon the mode of deposition and origin of the Permian
+sediments.
+</p>
+
+<p class="indent">
+The <i>Cœlenterates</i> are represented in the Permian by
+but a few Corals. These belong partly to the <i>Tabulate</i> and
+partly to the <i>Rugose</i> division; but the latter great group,
+so abundantly represented in Silurian, Devonian, and Carboniferous
+seas, is now extraordinarily reduced in numbers, the British
+strata of this age yielding only species of the single genus
+<i>Polycœlia</i>. So far, therefore, as at present known, all
+the characteristic genera of the Rugose Corals of the Carboniferous
+had become extinct before the deposition of the limestones of
+the Middle Permian.
+</p>
+
+<p class="indent">
+The <i>Echinoderms</i> are represented by a few <i>Crinoids</i>,
+and by a Sea-urchin belonging to the genus <i>Eocidaris</i>. The
+latter genus is nearly allied to the <i>Archœocidaris</i>
+of the Carboniferous, so that this Permian form belongs to a
+characteristically Palæozoic type.
+</p>
+
+<p class="indent">
+A few <i>Annelides</i> (<i>Spirorbis, Vermilia</i>, &amp;c.) have
+been described, but are of no special importance. Amongst the
+<i>Crustaceans</i>, however, we have to note the total absence
+of the great Palæozoic group of the <i>Trilobites</i>; whilst
+the little <i>Ostracoda</i> and <i>Phyllopods</i> still continue
+to be represented. We have also to note the first appearance
+here of the "Short-tailed" Decapods or Crabs (<i>Brachyura</i>),
+the highest of all the groups of <i>Crustacea</i>, in the person
+of <i>Hemitrochiscus paradoxus</i>, an extremely minute Crab
+from the Permian of Germany.
+</p>
+
+<p class="indent">
+<a name="page_198"><span class="page">Page 198</span></a>
+Amongst the <i>Mollusca</i>, the remains of <i>Polyzoa</i> may
+fairly be said to be amongst the most abundant of all the fossils
+of the Permian formation, The principal forms of these are the
+fronds of the Lace-corals (<i>Fenestella, Retepora</i>, and
+<i>Synocladia</i>), which are very abundant in the Magnesian
+Limestone of the north of England, and belong to various highly
+characteristic species (such as <i>Fenestella retiformis, Retepora
+Ehrenbergi</i>, and <i>Synocladia virgulacea</i>). The
+<i>Brachiopoda</i> are also represented in moderate numbers in the
+Permian. Along with species of the persistent genera <i>Discina,
+Crania</i>, and <i>Lingula</i>, we still meet with representatives of
+the old groups <i>Spirifera, Athyris</i>, and <i>Streptorhynchus</i>;
+and the Carboniferous <i>Productœ</i> yet survive under
+well-marked and characteristic types, though in much-diminished
+numbers. The species of Brachiopods here figured (fig. 135) are
+characteristic of the Magnesian Limestone in Britain and of the
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 495px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig135.jpg" width="487" height="232" alt="Fig. 135" />
+<br />
+Fig. 135.&mdash;Brachiopods of the Permian formation. <i>a,
+Producta horrida; b, Lingula Credneri; c, Terebratula elongata;
+d</i> and <i>e, Camarophoria globulina</i>. (After King.)
+</span>
+</span>
+
+corresponding strata on the Continent. Upon the whole, the most
+characteristic Permian <i>Brachiopods</i> belong to the genera
+<i>Producta, Strophalosia</i>, and <i>Camarophoria</i>.
+</p>
+
+<p class="indent">
+The <i>Bivalves</i> (<i>Lamellibranchiata</i>) have a tolerably
+varied development in the Permian rocks; but nearly all the old
+types, except some of those which occur in the Carboniferous, have
+now disappeared. The principal Permian Bivalves belong to the groups
+of the Pearl Oysters (<i>Aviculidœ</i>) and the
+<i>Trigoniadœ</i>, represented by genera such as <i>Bakewellia</i>
+and <i>Schizodus</i>; the true Mussels (<i>Mytilidœ</i>),
+represented by species which have been referred to <i>Mytilus</i>
+itself; and the Arks (<i>Arcadœ</i>), represented by species
+of the genera <i>Arca</i> (fig. 136) and <i>Byssoarca</i>. The first
+and last of these three families have a very ancient origin; but
+the family of the <i>Trigoniadœ</i>, though
+<a name="page_199"><span class="page">Page 199</span></a>
+feebly represented at the present day, is one which attained
+its maximum development in the Mesozoic period.
+</p>
+
+<p class="indent">
+The <i>Univalves</i> (<i>Gasteropoda</i>) are rare, and do not
+demand special notice. It may be observed, however, that the
+
+<span style="float: right; margin: 4px; width: 258px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig136.jpg" width="250" height="214" alt="Fig. 136" />
+<br />
+Fig. 136.&mdash;<i>Arca antiqua</i>. Permian.
+</span>
+
+Palæozoic genera <i>Euomphalus, Murchisonia, Loxonema</i>,
+and <i>Macrocheilus</i> are still in existence, together with the
+persistent genus <i>Pleurotomaria</i>. <i>Pteropods</i> of the
+old genera <i>Theca</i> and <i>Conularia</i> have been discovered;
+but the first of these characteristically Palæozoic types
+finally dies out here, and the second only survives but a short time
+longer. Lastly, a few <i>Cephalopods</i> have been found, still
+wholly referable to the Tetrabranchiate group, and belonging
+to the old genera <i>Orthoceras</i> and <i>Cyrtoceras</i> and
+the long-lived <i>Nautilus</i>.
+</p>
+
+<p class="indent">
+Amongst <i>Vertebrates</i>, we meet in the Permian period not
+only with the remains of Fishes and Amphibians, but also, for
+the first time, with true Reptiles. The <i>Fishes</i> are mainly
+<i>Ganoids</i>, though there are also remains of a few Cestraciont
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 375px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig137.jpg" width="367" height="250" alt="Fig. 137" />
+<br />
+Fig. 137.&mdash;<i>Platysomus gibbosus</i>, a "heterocercal"
+Ganoid, from the Middle Permian of Russia.
+</span>
+</span>
+
+Sharks. Not only are the <i>Ganoids</i> still the predominant group
+of Fishes, but all the known forms possess the unsymmetrical
+("heterocercal") tail which is so characteristic of the
+Palæozoic Ganoids. Most of the remains of the Permian Fishes
+have been obtained from the "Marl-slate" of Durham and the
+corresponding "Kupfer-schiefer" of Germany, on the horizon
+<a name="page_200"><span class="page">Page 200</span></a>
+of the Middle Permian; and the principal genera of the Ganoids
+are <i>Palœoniscus</i> and <i>Platysomus</i> (fig. 137).
+</p>
+
+<p class="indent">
+The <i>Amphibians</i> of the Permian period belong principally
+to the order of the <i>Labyrinthodonts</i>, which commenced to
+be represented in the Carboniferous, and has a large development
+in the Trias. Under the name, however, of <i>Palœosiren
+Beinerti</i>, Professor Geinitz has described an Amphibian from
+the Lower Permian of Germany, which he believes to be most nearly
+allied to the existing "Mud-eel" (<i>Siren lacertina</i>) of
+North America, and therefore to be related to the Newts and
+Salamanders (<i>Urodela</i>).
+</p>
+
+<p class="indent">
+Finally, we meet in the Permian deposits with the first undoubted
+remains of true <i>Reptiles</i>. These are distinguished, as a
+class, from the <i>Amphibians</i>, by the fact that they are
+air-breathers throughout the whole of their life, and therefore
+are at no time provided with gills; whilst they are exempt from
+that metamorphosis which all the <i>Amphibia</i> undergo in early
+life, consequent upon their transition from an aquatic to a more
+or less purely aerial mode of respiration. Their skeleton is well
+ossified; they usually have horny or bony plates, singly or in
+combination, developed in the skin; and their limbs (when present)
+are never either in the form of <i>fins</i> or <i>wings</i>,
+though sometimes capable of acting in either of these capacities,
+and liable to great modifications of form and structure. Though
+there can be no doubt whatever as to the occurrence of genuine
+Reptiles in deposits of unquestionable Permian age, there is
+still uncertainty as to the precise number of types which may
+have existed at this period. This uncertainty arises partly from
+the difficulty of deciding in all cases. whether a given bone
+be truely Labyrinthodont or Reptilian, but more especially from
+the confusion which exists at present between the Permian and
+the overlying Triassic deposits. Thus there are various deposits
+in different regions which have yielded the remains of Reptiles,
+and which cannot in the meanwhile be definitely referred either
+to the Permian series or to the Trias by clear stratigraphical
+or palæontological evidence. All that can be done in such
+cases is to be guided by the characters of the Reptiles themselves,
+and to judge by their affinities to remains from known Triassic
+or Permian rocks to which of these formations the beds containing
+them should be referred; but it is obvious that this method of
+procedure is seriously liable to lead to error. In accordance,
+however, with this, the only available mode of determination
+in some cases, the remains of <i>Thecodontosaurus</i> and
+<i>Palæosaurus</i> discovered in the dolomitic conglomerates
+<a name="page_201"><span class="page">Page 201</span></a>
+near Bristol will be considered as Triassic, thus leaving
+<i>Protorosaurus</i>[20] as the principal and most important
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 552px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig138.jpg" width="546" height="608" alt="Fig. 138" />
+<br />
+Fig. 138.&mdash;<i>Protorosaurus Speneri</i>, Middle Permian,
+Thuringia, reduced in size. (After Von Meyer.) [Copied from
+Dana.
+</span>
+</span>
+
+representative of the Permian Reptiles.[21] The type-species
+of the genus <i>Protorusaurus</i> is the <i>P. Speneri</i>(fig.
+138) of the "Kupfer-schiefer" of
+<a name="page_202"><span class="page">Page 202</span></a>
+Thuringia, but other allied
+species have been detected in the Middle Permian of Germany and
+the north of England. This Reptile attained a length of from
+three to four feet; and it has been generally referred to the
+group of the Lizards (<i>Lacertilia</i>), to which it is most
+nearly allied in its general structure, at the same time that it
+differs from all existing members of this group in the fact that
+its numerous conical and pointed teeth were implanted in distinct
+sockets in the jaws&mdash;this being a Crocodilian character. In
+other respects, however, <i>Protorosaurus</i> approximates closely
+to the living Monitors (<i>Varanidœ</i>); and the fact that
+the bodies of the vertebræ are slightly cupped or hollowed
+out at the ends would lead to the belief that the animal was aquatic
+in its habits. At the same time, the structure of the hind-limbs
+and their bony supports proves clearly that it must have also
+possessed the power of progression upon the land. Various other
+Reptilian bones have been described from the Permian formation, of
+which some are probably really referable to Labyrinthodonts, whilst
+others are regarded by Professor Owen as referable to the order of
+the "Theriodonts," in which the teeth are implanted in sockets,
+and resemble those of carnivorous quadrupeds in consisting of
+three groups in each jaw (namely, incisors, canines, and molars).
+Lastly, in red sandstones of Permian age in Dumfriesshire have
+been discovered the tracks of what would appear to have been
+<i>Chelonians</i> (Tortoises and Turtles); but it would not be
+safe to accept this conclusion as certain upon the evidence of
+footprints alone. The <i>Chelichnus Duncani</i>, however, described
+by Sir William Jardine in his magnificent work on the 'Ichnology
+of Annandale,' bears a great resemblance to the track of a Turtle.
+</p>
+
+<p class="footnote">
+[Footnote 20: Though commonly spelt as above, it is probable
+that the name of this Lizard was really intended to have been
+<i>Proterosaurus</i>&mdash;from the Greek <i>proteros</i>, first;
+and <i>saura</i>, lizard: and this spelling is followed by many
+writers.]
+</p>
+
+<p class="footnote">
+[Footnote 21: In an extremely able paper upon the subject (Quart.
+Journ. Geol. Soc., vol. xxvi.), Mr Etheridge has shown that there
+are good physical grounds for regarding the dolomitie conglomerate
+of Bristol as of Triassic age, and as probably corresponding in
+time with the Muschelkalk of the Continent.]
+</p>
+
+<p class="indent">
+No remains of Birds or Quadrupeds have hitherto been detected
+in deposits of Permian age.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following works may be consulted by the student with regard
+to the Permian formation and its fossils:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>"On the Geological Relations and Internal Structure of the
+  Magnesian Limestone and the Lower Portions of the New Red
+  Sandstone Series, &amp;c."&mdash;'Trans. Geol. Soc.,' ser. 2,
+  vol. iii. Sedgwick.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'The Geology of Russia in Europe.' Murchison, De Verneuil,
+  and Von Keyserling.</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Siluria,' Murchison.</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>'Permische System in Sachsen.' Geinitz and
+  Gutbier.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>'Die Versteinerungen des Deutschen Zechsteingebirges,'
+  Geinitz.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>'Die Animalischen Ueberreste der Dyas.'
+  Geinitz.</td></tr>
+<tr><td class="right" valign="top">
+<a name="page_203"><span class="page">Page 203</span></a>
+  (7)</td>
+ <td>'Monograph of the Permian Fossils of England'
+  (Palæontographical Society). King.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>'Monograph of the Permian Brachiopoda of Britain'
+(Palæontographical Society). Davidson.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>"On the Permian Rocks of the North-West of England and
+  their Extension into Scotland"&mdash;'Quart. Journ. Geol.
+  Soc.,' vol. xx. Murchison and Harkness.</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Catalogue of the Fossils of the Permian System of the
+  Counties of Northumberland and Durham.' Howse.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'Petrefacta Germaniæ.' Goldfuss.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>'Beitr&auml;ge zur Petrefaktenkunde.' Munster.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>'Ein Beitrag zur Palæontologie des Deutschen
+  Zechsteingebirges.' Von Schauroth.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>'Saurier aus dem Kupfer-schiefer der
+  Zechstein-formation.' Von Meyer.</td></tr>
+<tr><td class="right" valign="top">(15)</td>
+ <td>'Manual of Palæontology.' Owen.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Recherches sur les Poissons Fossiles.'
+  Agassiz.</td></tr>
+<tr><td class="right" valign="top">(17)</td>
+ <td>'Ichnology of Annandale.' Sir William Jardine.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>'Die Fossile Flora der Permischen Formation.'
+  Gœppert.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>'Genera et Species Plantarum Fossilium.' Unger.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>"On the Red Rocks of England of older Date than the
+  Trias"&mdash;'Quart. Journ. Geol. Soc.,' vol. xxvii.
+  Ramsay.</td></tr>
+</table>
+
+<h3>CHAPTER XV.</h3>
+
+<p class="subtitle">
+THE TRIASSIC PERIOD.
+</p>
+
+<p class="indent">
+We come now to the consideration of the great <i>Mesozoic</i>, or
+Secondary series of formations, consisting, in ascending order,
+of the Triassic, Jurassic, and Cretaceous systems. The Triassic
+group forms the base of the Mesozoic series, and corresponds
+with the higher portion of the New Red Sandstone of the older
+geologists. Like the Permian rocks, and as implied by its name,
+the <i>Trias</i> admits of a subdivision into three groups&mdash;a
+Lower, Middle, and Upper Trias. Of these sub-divisions the middle
+one is wanting in Britain; and all have received German names,
+being more largely and typically developed in Germany than in any
+other country. Thus, the Lower Trias is known as the <i>Bunter
+Sandstein</i>; the Middle Trias is called the <i>Muschelkalk</i>;
+and the Upper Trias is known as the <i>Keuper</i>.
+</p>
+
+<p class="indent">
+I. The lowest division of the Trias is known as the <i>Bunter
+Sandstein</i> (the <i>Grès bigarré</i> of the French),
+from the generally variegated colours of the beds which compose it
+(German, <i>bunt</i>, variegated). The Bunter Sandstein of the
+continent of Europe consists of red and white sandstones, with red
+<a name="page_204"><span class="page">Page 204</span></a>
+clays, and thin limestones, the whole
+attaining a thickness of about 1500 feet. The term "marl" is very
+generally employed to designate the clays of the Lower and Upper
+Trias; but the term is inappropriate, as they may contain no lime,
+and are therefore not always genuine marls. In Britain the Bunter
+Sandstein consists of red and mottled sandstones, with
+unconsolidated conglomerates, or "pebble-beds," the whole having a
+thickness of 1000 to 2000 feet. The Bunter Sandstein, as a rule,
+is very barren of fossils.
+</p>
+
+<p class="indent">
+II. The Middle Trias is not developed in Britain, but it is largely
+developed in Germany, where it constitutes what is known as the
+<i>Muschelkalk</i> (Germ. <i>Muschel</i>, mussel; <i>kalk</i>,
+limestone), from the abundance of fossil shells which it contains.
+The Muschelkalk (the <i>Calcaire coquillier</i> of the French)
+consists of compact grey or yellowish limestones, sometimes
+dolomitic, and including occasional beds of gypsum and rock-salt.
+</p>
+
+<p class="indent">
+III. The Upper Trias, or <i>Keuper</i> (the <i>Marnes
+irisées</i> of the French), as it is generally called,
+occurs in England; but is not so well developed as it is in
+Germany. In Britain, the Keuper is 1000 feet or more in thickness,
+and consists of white and brown sandstones, with red marls, the
+whole topped by red clays with rock-salt and gypsum.
+</p>
+
+<p class="indent">
+The Keuper in Britain is extremely unfossiliferous; but it passes
+upwards with perfect conformity into a very remarkable group of
+beds, at one time classed with the Lias, and now known under
+the names of the Penarth beds (from Penarth, in Glamorganshire),
+the Rhætic beds (from the Rhætic Alps), or the <i>Avicula
+contorta</i> beds (from the occurrence in them of great numbers
+of this peculiar Bivalve). These singular beds have been variously
+regarded as the highest beds of the Trias, or the lowest beds of
+the Lias, or as an intermediate group. The phenomena observed
+on the Continent, however, render it best to consider them as
+Triassic, as they certainly agree with the so-called Upper St
+Cassian or Kössen beds which form the top of the Trias in the
+Austrian Alps.
+</p>
+
+<p class="indent">
+The Penarth beds occur in Glamorganshire, Gloucestershire,
+Warwickshire, Staffordshire, and the north of Ireland; and they
+generally consist of a small thickness of grey marls, white
+limestones, and black shales, surmounted conformably by the lowest
+beds of the Lias. The most characteristic fossils which they
+contain are the three Bivalves <i>Cardium Rhœticum, Avicula
+contorta</i>, and <i>Pecten Valoniensis</i>; but they have yielded
+many other fossils, amongst which the most important are the
+remains of Fishes and small Mammals (<i>Microlestes</i>).
+</p>
+
+<p class="indent">
+In the Austrian Alps the Trias terminates upwards in an
+<a name="page_205"><span class="page">Page 205</span></a>
+extraordinary series of fossiliferous beds, replete with
+marine fossils. Sir Charles Lyell gives the following table of
+these remarkable deposits:&mdash;
+</p>
+
+<p class="center">
+<i>Strata below the Lias in the Austrian Alps, in descending
+order.</i>
+</p>
+<table border="1" cellspacing="0" cellpadding="4">
+<tr><td>
+ <table border="0" cellspacing="0">
+  <tr><td valign="top">1.</td>
+   <td valign="top">Koessen beds.<br/>(Synonyms, Upper St Cassian
+    beds of Escher and Merian.</td></tr>
+ </table>
+</td><td colspan="2">
+ Grey and black limestone, with calcareous marls having a thickness
+ of about 50 feet. Among the fossils, Brachiopoda very numerous;
+ some few species common to the genuine Lias; many peculiar.
+ <i>Avicula contorta, Pecten Valoniensis, Cardium Rhœticum,
+ Avicula inœquivalvis, Spirifer M&uuml;nsteri</i>, Dav.
+ Strata containing the above fossils alternate with the Dachstein
+ beds, lying next below.
+</td></tr>
+
+<tr><td>
+ <table border="0" cellspacing="0">
+  <tr><td valign="top">2.</td>
+   <td valign="top">Dachstein beds.</td></tr>
+ </table>
+</td><td colspan="2">
+ White or greyish limestone, often in beds three or four feet
+ thick. Total thickness of the formation above 2000 feet. Upper
+ part fossiliferous, with some strata composed of corals
+ (<i>Lithodendron</i>.) Lower portion without fossils. Among the
+ characteristic shells are <i>Hemicardium</i> <i>Wulfeni,
+ Megalodon triqueler</i>, and other large bivalves.
+</td></tr>
+
+<tr><td>
+ <table border="0" cellspacing="0">
+  <tr><td valign="top">3.</td>
+   <td valign="top">Hallstadt beds<br/>(or St Cassian)</td></tr>
+ </table>
+</td><td colspan="2">
+ Red, pink, or white marbles, from 800 to 1000 feet in thickness,
+ containing more than 800 species of marine fossils, for the most
+ part mollusca. Many species of <i>Orthoceras</i>. True
+ <i>Ammonites</i>, besides <i>Ceratites</i> and <i>Goniatites,
+ Belemnites</i> (rare), <i>Porcellia, Pleurotomania, Trochus,
+ Monotis salinaria</i>, &amp;c.
+</td></tr>
+
+<tr><td>
+ <table border="0" cellspacing="0">
+  <tr><td valign="top" rowspan="2">4.</td>
+   <td valign="top"><i>A</i>.</td>
+   <td valign="top">Guttenstein beds.</td></tr>
+  <tr><td valign="top"><i>B</i>.</td>
+   <td valign="top">Werfen beds, base of Upper Trias?<br/>Lower
+    Trias of some geologists.</td></tr>
+ </table>
+</td><td>
+ <table border="0" cellspacing="0">
+  <tr><td valign="top"><i>A</i>.</td>
+   <td valign="top">Black and grey limestone 150 feet thick,
+    alternating with the underlying Werfen beds.</td></tr>
+  <tr><td valign="top"><i>B</i>.</td>
+   <td valign="top">Red and green shale and sandstone, with salt
+    and gypsum.</td></tr>
+ </table>
+</td><td>
+ Among the fossils are <i>Ceratites cassianus, Myacites fassaensis,
+ Naticella costata</i>, &amp;c.
+</td></tr>
+</table>
+
+<p class="indent">
+In the United States, rocks of Triassic age occur in several
+areas between the Appalachians and the Atlantic seaboard; but
+they show no such triple division as in Germany, and their exact
+place in the system is uncertain. The rocks of these areas consist
+of red sandstones, sometimes shaly or conglomeratic, occasionally
+with beds of impure limestone. Other more extensive areas where
+Triassic rocks appear at the surface, are found west of the
+Mississippi, on the slopes of the Rocky Mountains, where the beds
+consist of sandstones and gypsiferous
+<a name="page_206"><span class="page">Page 206</span></a>
+marls. The American Trias is chiefly remarkable for having yielded
+the remains of a small Marsupial (<i>Dromatherium</i>), and numerous
+footprints, which have generally been referred to Birds
+(<i>Brontozoum</i>), along with the tracks of undoubted Reptiles
+(<i>Otozoum, Anisopus</i>, &amp;c.)
+</p>
+
+<p class="indent">
+The subjoined section (fig. 139) expresses, in a diagrammatic
+manner, the general sequence of the Triassic rocks when fully
+developed, as, for example, in the Bavarian Alps:&mdash;
+</p>
+
+<div class="center">
+<table border="0" width="550">
+<tr><td class="center"><span class="image">
+GENERALIZED SECTION OF THE TRIASSIC ROCKS OF CENTRAL EUROPE.
+</span></td></tr>
+<tr><td class="center"><span class="image">Fig.
+  139.</span></td></tr>
+<tr><td>
+<img src="images/fig139.jpg" width="546" height="628" alt="Fig. 139" />
+</td></tr>
+</table>
+</div>
+
+<p class="indent">
+With regard to the <i>life</i> of the Triassic period, we have to
+<a name="page_207"><span class="page">Page 207</span></a>
+notice a difference as concerns the
+different members of the group similar to that which has been
+already mentioned in connection with the Permian formation. The
+arenaceous deposits of the series, namely, resemble those of the
+Permian, not only in being commonly red or variegated in their
+colour, but also in their conspicuous paucity of organic remains.
+They for the most part are either wholly unfossiliferous, or they
+contain the remains of plants or the bones of reptiles, such as
+may easily have been drifted from some neighbouring shore. The
+few fossils which may be considered as properly belonging to
+these deposits are chiefly Crustaceans (<i>Estheria</i>) or
+Fishes, which may well have lived in the waters of estuaries or
+vast inland seas. We may therefore conclude, with considerable
+probability, that the barren sandy and marly accumulations of
+the Bunter Sandstein and Lower Keuper were not laid down in an
+open sea, but are probably brackish-water deposits, formed in
+estuaries or land-locked bodies of salt water. This at any rate
+would appear to be the case as regards these members of the
+series as developed in Britain and in their typical areas on
+the continent of Europe; and the origin of most of the North
+American Trias would appear to be much the same. Whether this
+view be correct or not, it is certain that the beds in question
+were laid down in <i>shallow</i> water, and in the immediate
+vicinity of <i>land</i>, as shown by the numerous drifted plants
+which they contain and the common occurrence in them of the
+footprints of air-breathing animals (Birds, Reptiles, and
+Amphibians). On the other hand, the middle and highest members
+of the Trias are largely calcareous, and are replete with the
+remains of undoubted marine animals. There cannot, therefore,
+be the smallest doubt but that the Muschelkalk and the Rhætic
+or Kössen beds were slowly accumulated in an open sea, of at
+least a moderate depth; and they have preserved for us a very
+considerable selection from the marine fauna of the Triassic
+period.
+</p>
+
+<p class="indent">
+The <i>plants</i> of the Trias are, on the whole, as distinctively
+Mesozoic in their aspect as those of the Permian are Palæozoic.
+In spite, therefore, of the great difficulty which is experienced
+in effecting a satisfactory stratigraphical separation between the
+Permian and the Trias, we have in this fact a proof that the two
+formations were divided by an interval of time sufficient to allow
+of enormous changes in the terrestrial vegetation of the world. The
+<i>Lepidodendroids, Asterophyllites</i>, and <i>Annulariœ</i>,
+of the Coal and Permian formations, have now apparently wholly
+disappeared: and the Triassic flora consists mainly of Ferns,
+Cycads, and Conifers, of which only the two
+<a name="page_208"><span class="page">Page 208</span></a>
+last need special
+notice. The <i>Cycads</i> (fig. 140) are true exogenous plants,
+which in general form and habit of growth present considerable
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 370px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig140.jpg" width="370" height="250" alt="Fig. 140" />
+<br />
+Fig. 140.&mdash;<i>Zamia spiralis</i>, a living Cycad. Australia.
+</span>
+</span>
+
+resemblance to young Palms, but which in reality are most nearly
+related to the Pines and Firs (<i>Coniferœ</i>). The trunk
+is unbranched, often much shortened, and bears a crown of feathery
+pinnate fronds. The leaves are usually "circinate"&mdash;they unroll
+in expanding, like the fronds of ferns. The seeds are not protected
+by a seed-vessel, but are borne upon the edge of altered leaves,
+or are carried on the scales of a cone. All the living species of
+Cycads are natives of warm countries, such as South America, the
+West Indies, Japan, Australia, Southern Asia, and South Africa.
+The remains of Cycads, as we have seen, are not known to occur
+in the Coal formation, or only to a very limited extent towards
+its close; nor are they known with certainty as occurring in
+Permian deposits. In the Triassic period, however, the remains
+of Cycads belonging to such genera as <i>Pterophyllum</i> (fig.
+141, <i>b</i>), <i>Zamites</i>, and <i>Podozamites</i> (fig. 141,
+<i>c</i>), are sufficiently abundant to constitute quite a marked
+feature in the vegetation; and they continue to be abundantly
+represented throughout the whole Mesozoic series. The name "Age
+of Cycads," as applied to the Secondary epoch, is therefore,
+from a botanical point of view, an extremely appropriate one.
+The <i>Conifers</i> of the Trias are not uncommon, the principal
+form being <i>Veltzia</i> (fig. 141, <i>a</i>), which possesses
+some peculiar characters, but would appear to be most nearly
+related to the recent Cypresses.
+</p>
+
+<p class="indent">
+As regards the <i>Invertebrate animals</i> of the Trias, our
+knowledge is still principally derived from the calcareous beds
+which constitute the centre of the system (the Muschelkalk)
+<a name="page_209"><span class="page">Page 209</span></a>
+on the continent
+of Europe, and from the St Cassain and Rhætic beds
+still higher in the series; whilst some of the Triassic strata
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 500px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig141.jpg" width="500" height="541" alt="Fig. 141" />
+<br />
+Fig. 141.&mdash;Triassic Conifers and Cycads. <i>a, Voltzia</i>
+(<i>Schizoneura</i>) <i>heterophylla</i>, portion of a branch,
+Europe and America; <i>b</i>, Part of the frond of
+<i>Pterophyllum Jœgeri</i>, Europe; <i>c</i>, Part of the
+frond of <i>Podozamites lanceolatus</i>, America.
+</span>
+</span>
+
+of California and Nevada have likewise yielded numerous
+remains of marine Invertebrates. The <i>Protozoans</i> are
+represented by <i>Foraminifera</i> and <i>Sponges</i>, and the
+<i>Cœlenterates</i> by a small number of <i>Corals</i>; but
+these require no special notice. It may be mentioned, however,
+that the great Palæozoic group of the <i>Rugose</i> corals
+has no known representative here, its place being taken by corals
+of Secondary type (such as <i>Montlivaltia, Synastœa</i>,
+&amp;c.)
+</p>
+
+<p class="indent">
+The <i>Echinoderms</i> are represented principally by
+<i>Crinoids</i>, the remains of which are extremely abundant
+in some of the limestones. The best-known species is the famous
+"Lily-Encrinite" (<i>Encrinus liliiformis</i>, fig. 142), which
+is characteristic
+<a name="page_210"><span class="page">Page 210</span></a>
+of the Muschelkalk. In this beautiful species,
+the flower-like head is supported upon a rounded stem, the joints
+
+<span style="float: left; margin: 4px; width: 148px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig142.jpg" width="148" height="526" alt="Fig. 142" />
+<br />
+Fig. 142.&mdash;Head and upper part of the column of <i>Encrinus
+liliiformis</i>. The lower figure shows the articulating surface
+of one of the joints of the column. Muschelkalk, Germany.
+</span>
+
+of which are elaborately articulated with one another; and the
+fringed arms are composed each of a double series of alternating
+calcareous pieces. The Palæozoic Urchins, with their
+supernumerary rows of plates, the Cystideans, and the Pentremites
+have finally disappeared; but both Star-fishes and Brittle-stars
+continue to be represented. One of the latter&mdash;namely, the
+
+<span style="float: right; margin: 4px; width: 365px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig143.jpg" width="365" height="151" alt="Fig. 143" />
+<br />
+Fig. 143.&mdash;<i>Aspidura loricata</i>, a Triassic
+Ophiuroid. Muschelkalk, Germany.
+</span>
+
+<i>Aspidura loricata</i> of Goldfuss (fig. 143)&mdash;is highly
+characteristic of the Muschelkalk.
+</p>
+
+<p class="indent">
+The remains of <i>Articulate Animals</i> are not very abundant in
+the Trias, if we except the bivalved cases of the little Water-fleas
+(<i>Ostracoda</i>), which are occasionally very plentiful. There
+are also many species of the horny, concentrically-striated valves
+of the <i>Estheriœ</i> (see fig. 122, <i>b</i>), which might
+easily be taken for small Bivalve Molluscs. The "Long-tailed"
+Decapods of the type of the Lobster, are not without examples
+but they become much more numerous in the succeeding Jurassic
+period. Remains of insects have also been discovered.
+</p>
+
+<p class="indent">
+Amongst the <i>Mollusca</i> we have to note the disappearance,
+amongst the lower groups, of many characteristic Palæozoic
+types. Amongst the <i>Polyzoans</i>, the characteristic "Lace-corals,"
+<i>Fenestella, Retepora</i>,[22] <i>Synocladia, Polypora</i>, &amp;c.,
+<a name="page_211"><span class="page">Page 211</span></a>
+have become apparently extinct. The same is true of many of the ancient
+types of <i>Brachiopods</i>, and conspicuously so of the great family
+of the <i>Productidœ</i>, which played such an important part in
+the seas of the Carboniferous and Permian periods.
+</p>
+
+<p class="footnote">
+[Footnote 22: The genus <i>Retefora</i> is really a recent one,
+represented by living forms; and the so-called <i>Reteporœ</i>
+of the Palæozoic rocks should properly receive another name
+(<i>Phyllopora</i>), as being of a different nature. The name
+<i>Retepora</i> has been here retained for these old forms simply
+in accordance with general usage.]
+</p>
+
+<p class="indent">
+<i>Bivalves</i> (<i>Lamellibranchiata</i>) and <i>Univalves</i>
+(<i>Gasteropoda</i>) are well represented in the marine beds of
+the Trias, and some of the former are particularly characteristic
+either of the formation as a whole or of minor subdivisions of it. A
+few of these characteristic species are figured in the accompanying
+illustration (fig. 144). Bivalve shells of the genera <i>Daonella</i>
+(fig. 144, <i>a</i>) and <i>Halobia</i> (<i>Monotis</i>) are very
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 464px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig144.jpg" width="464" height="363" alt="Fig. 144" />
+<br />
+Fig. 144. Triassic Lamellibranchs. <i>a, Daonella</i> (<i>Halobia</i>)
+<i>Lommelli; b, Pecten Valoniensis; c, Myophoria lineata; d. Cardium
+Rhœticum; e. Avicula contorta; f. Avicula socialis</i>.
+</span>
+</span>
+
+abundant, and are found in the Triassic strata of almost all
+regions. These groups belong to the family of the Pearl-oysters
+(<i>Aviculidœ</i>), and are singular from the striking
+resemblance borne by some of their included forms to the
+<i>Strophomenœ</i> amongst the Lamp-shells, though, of course,
+no real relation exists between the two. The little Pearl-oyster,
+<i>Avicula socialis</i> (fig. 144, <i>f</i>), is found throughout
+the greater part of the Triassic series, and is especially abundant
+in the Muschelkalk. The genus <i>Myophoria</i> (fig. 144, <i>c</i>),
+belonging to the <i>Trigoniadœ</i>, and related therefore to
+the Permian <i>Schizodus</i>, is characteristically Triassic, many
+species of the genus being known in deposits of this age. Lastly,
+the so-called "Rhætic" or "Kössen" beds are
+<a name="page_212"><span class="page">Page 212</span></a>
+characterised by the occurrence in them of the Scallop,
+<i>Pecten Valoniensis</i> (fig. 144, <i>b</i>); the small Cockle,
+<i>Cardium Rhœticum</i> (fig. 144, <i>d</i>); and the
+curiously-twisted Pearl-oyster, <i>Avicula contorta</i> (fig. 144,
+<i>e</i>)&mdash;this last Bivalve being so abundant that the strata
+in question are often spoken of as the "Avicula contorta beds."
+</p>
+
+<p class="indent">
+Passing over the groups of the <i>Heteropods</i> and
+<i>Pteropods</i>, we have to notice the <i>Cephalopoda</i>, which
+are represented in the Trias not only by the chambered shells
+of <i>Tetrabranchiates</i>, but also, for the first time, by
+the internal skeletons of <i>Dibranchiate</i> forms. The Trias,
+therefore, marks the first recognised appearance of true
+Cuttle-fishes. All the known examples of these belong to the great
+Mesozoic group of the <i>Belemnitidœ</i>; and as this family
+is much more largely developed in the succeeding Jurassic period,
+the consideration of its characters will be deferred till that
+formation is treated of. Amongst the chambered <i>Cephalopods</i>
+we find quite a number of the Palæozoic <i>Orthoceratites</i>,
+some of them of considerable size, along with the ancient
+<i>Cyrtoceras</i> and <i>Goniatites</i>; and these old types,
+singularly enough, occur in the higher portion of the Trias (St
+Cassian beds), but have, for some unexplained reason, not yet
+been recognised in the lower and equally fossiliferous formation
+of the Muschelkalk. Along with these we meet for the first time
+with true <i>Ammonites</i>, which fill such an extensive place
+
+<span style="float: left; margin: 4px; width: 332px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig145.jpg" width="322" height="281" alt="Fig. 145" />
+<br />
+Fig. 145.&mdash;<i>Ceratites nodosus</i>, viewed from the side and
+from behind. Muschelkalk.
+</span>
+
+in the Jurassic seas, and which will be spoken of hereafter. The
+form, however, which is most characteristic of the Trias is
+<i>Ceratites</i> (fig. 145). In this genus the shell is curved
+into a flat spiral, the volutions of which are in contact; and it
+further agrees with both <i>Goniatites</i> and <i>Ammonites</i>
+in the fact that the septa or partitions between the air-chambers
+are not simple and plain (as in the <i>Nautilus</i> and its allies),
+but are folded and bent as they approach the outer wall of the
+shell. In the <i>Goniatite</i> these foldings of the septa are
+of a simply lobed or angulated nature, and in the <i>Ammonite</i>
+<a name="page_213"><span class="page">Page 213</span></a>
+they are extremely complex; whilst in the
+<i>Ceratite</i> there is an intermediate state of things, the
+special feature of which is, that those foldings which are turned
+towards the mouth of the shell are merely rounded, whereas those
+which are turned away from the mouth are characteristically
+toothed. The genus <i>Ceratites</i>, though principally Triassic,
+has recently been recognised in strata of Carboniferous age in
+India.
+</p>
+
+<p class="indent">
+From the foregoing it will be gathered that one of the most important
+points in connection with the Triassic <i>Mollusca</i> is the
+remarkable intermixture of Palæozoic and Mesozoic types which
+they exhibit. It is to be remembered, also, that this intermixture
+has hitherto been recognised, not in the Middle Triassic limestones
+of the Muschelkalk, in which&mdash;as the oldest Triassic beds with
+marine fossils&mdash;we should naturally expect to find it, but in
+the St Cassian beds, the age of which is considerably later than
+that of the Muschelkalk. The intermingling of old and new types of
+Shell-fish in the Upper Trias is well brought out in the annexed
+table, given by Sir Charles Lyell in his 'Student's Elements of
+Geology' (some of the less important forms in the table being
+omitted here):&mdash;
+</p>
+
+<p class="center">
+GENERA OF FOSSIL MOLLUSCA IN THE ST CASSIAN AND HALLSTADT BEDS.
+</p>
+
+<table border="0" cellspacing="0" cellpadding="4" width="100%">
+<tr><td valign="top" class="genera">
+  Common to Older Rocks.
+</td><td valign="top" class="genera">
+  Characteristic of Triassic Rocks.
+</td><td valign="top" class="genera">
+  Common to Newer Rocks.
+</td></tr>
+
+<tr><td valign="top" class="genera">
+  <table border="0" cellspacing="0" cellpadding="0">
+   <tr><td class="left">Orthoceras.</td></tr>
+   <tr><td class="left">Bactrites.</td></tr>
+   <tr><td class="left">Macrocheilus.</td></tr>
+   <tr><td class="left">Loxonema.</td></tr>
+   <tr><td class="left">Holopella.</td></tr>
+   <tr><td class="left">Murchisonia.</td></tr>
+   <tr><td class="left">Porcellia.</td></tr>
+   <tr><td class="left">Athyris.</td></tr>
+   <tr><td class="left">Retzia.</td></tr>
+   <tr><td class="left">Cyrtina.</td></tr>
+   <tr><td class="left">Euomphalus.</td></tr>
+  </table>
+</td><td valign="top" class="genera">
+  <table border="0" cellspacing="0" cellpadding="0">
+   <tr><td class="left">Ceratites.</td></tr>
+   <tr><td class="left">Cochloceras.</td></tr>
+   <tr><td class="left">Rhabdoceras.</td></tr>
+   <tr><td class="left">Aulacoceras.</td></tr>
+   <tr><td class="left">Naticella.</td></tr>
+   <tr><td class="left">Platystoma.</td></tr>
+   <tr><td class="left">Halobia.</td></tr>
+   <tr><td class="left">Hörnesia.</td></tr>
+   <tr><td class="left">Koninckia.</td></tr>
+   <tr><td class="left">Scoliostoma.</td></tr>
+   <tr><td class="left">Myophoria.</td></tr>
+  </table>
+  (The last two are principally but not exclusively Triassic.)
+</td><td valign="top" class="genera">
+  <table border="0" cellspacing="0" cellpadding="0">
+   <tr><td class="left">Ammonites.</td></tr>
+   <tr><td class="left">Chemnitzia.</td></tr>
+   <tr><td class="left">Cerithium.</td></tr>
+   <tr><td class="left">Monodonta.</td></tr>
+   <tr><td class="left">Sphœra.</td></tr>
+   <tr><td class="left">Cardita.</td></tr>
+   <tr><td class="left">Myoconcha.</td></tr>
+   <tr><td class="left">Hinnites.</td></tr>
+   <tr><td class="left">Monotis.</td></tr>
+   <tr><td class="left">Plicatula.</td></tr>
+   <tr><td class="left">Pachyrisma.</td></tr>
+   <tr><td class="left">Thecidium.</td></tr>
+  </table></td></tr>
+</table>
+
+<p class="indent">
+Thus, to emphasise the more important points alone, the Trias
+has yielded, amongst the Gasteropods, the characteristically
+Palæozoic <i>Loxonema, Holopella, Murchisonia, Euomphalus</i>,
+and <i>Porcellia</i>, along with typically Triassic forms like
+<i>Platystoma</i> and <i>Scoliostoma</i>, and the great modern
+groups <i>Chemnitzia</i> and <i>Cerithium</i>. Amongst the Bivalves
+we find the Palæozoic <i>Megalodon</i> side by side with the
+Triassic <i>Halobia</i> and <i>Myophoria</i>, these being associated
+with the <i>Carditœ, Hinnites, Plicatulœ</i>, and
+<i>Trigoniœ</i> of later deposits. The Brachiopods
+<a name="page_214"><span class="page">Page 214</span></a>
+exhibit the Palæozoic <i>Athyris, Retzia</i>, and
+<i>Cyrtina</i>, with the Triassic <i>Koninckia</i> and the modern
+<i>Thecidium</i>. Finally, it is here that the ancient genera
+<i>Orthoceras, Cyrtoceras</i>, and <i>Goniatites</i> make their
+last appearance upon the scene of life, the place of the last of
+these being taken by the more complex and almost exclusively
+Triassic <i>Ceratites</i>, whilst the still more complex genus
+<i>Ammonites</i> first appears here in force, and is never again
+wanting till we reach the close of the Mesozoic period. The first
+representatives of the great Secondary family of the
+<i>Belemnites</i> are also recorded from this horizon.
+</p>
+
+<p class="indent">
+Amongst the <i>Vertebrate Animals</i> of the Trias, the <i>Fishes</i>
+are represented by numerous forms belonging to the <i>Ganoids</i> and
+the <i>Placoids</i>. The Ganoids of the period are still all provided
+with unsymmetrical ("heterocercal") tails, and belong principally
+to such genera as <i>Palœoniscus</i> and <i>Catopterus</i>.
+The remains of Placoids are in the form of teeth and spines, the
+two principal genera being the two important Secondary groups
+<i>Acrodus</i> and <i>Hybodus</i>. Very nearly at the summit
+of the Trias in England, in the Rhætic series, is a singular
+stratum, which is well known as the "bone-bed," from the number
+of fish-remains which it contains. More interesting, however,
+than the above, are the curious palate-teeth of the Trias, upon
+which Agassiz founded the genus <i>Ceratodus</i>. The teeth of
+Ceratodus (fig. 146) are singular flattened plates, composed
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 441px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig146.jpg" width="441" height="151" alt="Fig. 146" />
+<br />
+Fig. 146.&mdash;<i>a</i>, Dental plate of <i>Ceratodus serratus</i>,
+Keuper; <i>b</i>, Dental plate of <i>Ceratodus altus</i>,
+Keuper; (After Agassiz.)
+</span>
+</span>
+
+of spongy bone beneath, covered superficially with a layer of
+enamel. Each plate is approximately triangular, one margin (which
+we now know to be the outer one) being prolonged into prongs or
+conical prominences, whilst the surface is more or less regularly
+undulated. Until recently, though the master-mind of Agassiz
+recognised that these singular bodies were undoubtedly the teeth
+of fishes, we were entirely ignorant as to their precise relation
+to the animal, or as to the exact affinities of the fish thus
+armed. Lately, however, there has been discovered in the rivers
+of Queensland (Australia) a living species of <i>Ceratodus</i>
+(<i>C. Fosteri</i>, fig. 147),
+<a name="page_215"><span class="page">Page 215</span></a>
+with teeth precisely similar to those
+of its Triassic predecessor; and we thus have become acquainted
+with the use of these structures and the manner in which they
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 528px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig147.jpg" width="528" height="107" alt="Fig. 147" />
+<br />
+Fig. 147.&mdash;<i>Ceratodus Fosteri</i>, the Australian Mud-fish,
+reduced in size.
+</span>
+</span>
+
+were implanted in the mouth. The palate carries two of these
+plates, with their longer straight sides turned towards each other,
+their sharply-sinuated sides turned outwards, and their short
+straight sides or bases directed backwards. Two similar plates in
+the lower jaw correspond to the upper, their undulated surfaces
+fitting exactly to those of the opposite teeth. There are also
+two sharp-edged front teeth, which are placed in the front of
+the mouth in the upper jaw; but these have not been recognised
+in the fossil specimens. The living <i>Ceratodus</i> feeds on
+vegetable matters, which are taken up or tom off from plants by
+the sharp front teeth, and then partially crushed between the
+undulated surfaces of the back teeth (G&uuml;nther); and there need
+be little doubt but that the Triassic <i>Ceratodi</i> followed
+a similar mode of existence. From the study of the living
+<i>Ceratodus</i>, it is certain that the genus belongs to the
+same group as the existing Mud-fishes (<i>Dipnoi</i>); and we
+therefore learn that this, the highest, group of the entire class
+of Fishes existed in Triassic times under forms little or not
+at all different from species now alive; whilst it has become
+probable that the order can be traced back into the Devonian
+period.
+</p>
+
+<p class="indent">
+The <i>Amphibians</i> of the Trias all belong to the old order
+of the <i>Labyrinthodonts</i>, and some of them are remarkable
+for their gigantic dimensions. They were first known by their
+footprints, which were found to occur plentifully in the Triassic
+sandstones of Britain and the continent of Europe, and which
+consisted of a double series of alternately-placed pairs of
+hand-shaped impressions, the hinder print of each pair being
+much larger than the one in front (fig. 148). So like were these
+impressions to the shape of the human hand, that the at that
+time unknown animal which produced them was at once christened
+<i>Cheirotherium</i>, or "Hand-beast." Further discoveries, however,
+soon showed that the footprints of <i>Cheirotherium</i> were really
+produced by species of Amphibians which, like the existing Frogs,
+possessed hind-feet of a much larger size than the fore-feet,
+<a name="page_216"><span class="page">Page 216</span></a>
+
+<span style="float:left; text-align: justify; width: 232px;
+             margin: 4px; font-size: smaller;">
+<img src="images/fig148a.jpg" width="232" height="312" alt="Fig. 148a" />
+</span>
+
+<span style="float: left; width: 100%; text-align: center;
+ clear: left;">
+
+<span style="margin: 4px; text-align: justify; width: 505px;
+             font-size: smaller;">
+<img src="images/fig148b.jpg" width="505" height="516" alt="Fig. 148b" />
+<br />
+Fig. 148.&mdash;Footprints of a Labyrinthodont (<i>Cheirotherium</i>),
+from the Triassic Sandstones of Hessberg, near Hildburghausen,
+Germany, reduced one-eighth. The lower figure shows a slab, with
+several prints, and traversed by reticulated sun-cracks: the upper
+figure shows the impression of one of the hind-feet, one-half of
+the natural size. (After Sickler.)
+</span>
+
+</span>
+
+and to which the name of <i>Labyrinthodonts</i> was applied in
+consequence of the complex microscopic structure of the teeth
+(fig. 149). In the essential details of their structure, the
+Triassic Labyrinthodonts did not differ materially from their
+predecessors in the Coal-measures and Permian rocks. They possessed
+the same frog-like skulls (fig. 150), with a lizard-like body, a
+long tail, and comparatively feeble limbs. The hind-limbs were
+stronger and longer than the fore-limbs, and the lower
+<a name="page_217"><span class="page">Page 217</span></a>
+surface of the body was protected by an armour of bony
+plates. Some of the Triassic Labyrinthodonts must have attained
+dimensions utterly unapproached amongst existing Amphibians, the
+skull of <i>Labyrinthodon Jœgeri</i> (fig. 150) being upwards
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 345px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig149.jpg" width="345" height="317" alt="Fig. 149" />
+<br />
+Fig. 149.&mdash;Section of the tooth of <i>Labryinthodon
+(Mastodonsaurus) Jœgeri</i>, showing the microscopic
+structure. Greatly enlarged. Trias.
+</span>
+
+<span style="width: 173px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig150.jpg" width="173" height="283" alt="Fig. 150" />
+<br />
+Fig. 150.&mdash;<i>a</i>, Skull of <i>Labyrinthodon Jœgeri</i>,
+much reduced in size; <i>b</i>, Tooth of the same. Trias
+W&uuml;rttemberg.
+</span>
+
+</span>
+
+of three feet in length and two feet in breadth. Restorations of
+some of these extraordinary creatures have been attempted in the
+guise of colossal Frogs; but they must in reality have more
+closely resembled huge Newts.
+</p>
+
+<p class="indent">
+Remains of <i>Reptiles</i> are very abundant in Triassic deposits,
+and belong to very varied types. The most marked feature, in fact,
+connected with the Vertebrate fauna of the Trias, and of the
+Secondary rocks in general, is the great abundance of Reptilian
+life. Hence the Secondary period is often spoken of as the "Age
+of Reptiles." Many of the Triassic reptiles depart widely in
+their structure from any with which we are acquainted as existing
+on the earth at the present day, and it is only possible here to
+briefly note some of the more important of these ancient forms.
+Amongst the group of the Lizards (<i>Lacertilia</i>), represented
+by <i>Protorosaurus</i> in the older Permian strata, three types
+more or less certainly referable to this order may be mentioned.
+One of these is a small reptile which was found many years ago
+in sandstones near Elgin, in Scotland, and which excited special
+interest at the time in consequence of the fact that the strata
+in question were believed to belong to the Old Red Sandstone
+formation. It is, however,
+<a name="page_218"><span class="page">Page 218</span></a>
+now certain that
+the Elgin sandstones which contain <i>Telerpeton Elginense</i>, as
+this reptile is termed, are really to be regarded as of Triassic
+age. By Professor Huxley, <i>Telerpeton</i> is regarded as a
+Lizard, which cannot be considered as "in any sense a less
+perfectly-organised creature than the Gecko, whose swift and
+noiseless run over walls and ceilings surprises the traveller
+in climates warmer than our own." The "Elgin Sandstones" have
+also yielded another Lizard, which was originally described by
+Professor Huxley under the name of <i>Hyperodapedon</i>, the
+remains of the same genus having been subsequently discovered
+in Triassic strata in India and South Africa. The Lizards of
+this group must therefore have at one time enjoyed a very wide
+distribution over the globe; and the living <i>Sphenodon</i> of
+New Zealand is believed by Professor Huxley to be the nearest
+living ally of this family. The <i>Hyperodapedon</i> of the
+Elgin Sandstones was about six feet in length, with limbs adapted
+for terrestrial progression, but with the bodies of the
+vertebræ slightly biconcave, and having two rows of palatal
+teeth, which become worn down to the bone in old age. Lastly, the
+curious <i>Rhynchosaurus</i> of the Trias is also referred, by
+the eminent comparative anatomist above mentioned, to the order
+of the Lizards. In this singular reptile
+
+<span style="float: left; margin: 4px; width: 254px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig151.jpg" width="237" height="125" alt="Fig. 151" />
+<br />
+Fig. 151.&mdash;Skull of <i>Rhynchosaurus articeps</i>. Trias.
+(After Owen.)
+</span>
+
+(fig. 151) the skull is somewhat bird-like, and the jaws appear
+to have been destitute of teeth, and to have been encased in a
+horny sheath like the beak of a Turtle or a Bird. It is possible,
+however, that the palate was furnished with teeth.
+</p>
+
+<p class="indent">
+The group of the Crocodiles and Alligators (<i>Crocadilia</i>),
+distinguished by the fact that the teeth are implanted in distinct
+sockets and the skin more or less extensively provided with bony
+plates, is represented in the Triassic rocks by the
+<i>Stagonolepis</i> of the Elgin Sandstones. The so-called
+"Thecodont" reptiles (such as <i>Belodon, Thecodontosaurus</i>,
+and <i>Palœosaurus</i>, fig. 152, <i>c, d, e</i>) are also
+nearly related to the Crocodiles, though it is doubtful if they
+should be absolutely referred to this group. In these reptiles, the
+teeth are implanted in distinct sockets in the jaws, their crowns
+being more or less compressed and pointed, "with trenchant and
+finely serrate margins" (Owen). The bodies of the vertebræ are
+hollowed out at both ends, but the limbs appear to be adapted
+for progression on the land. The genus <i>Belodon</i> (fig. 152,
+<i>c</i>) is known to occur in the Keuper of Germany and in America;
+<a name="page_219"><span class="page">Page 219</span></a>
+and <i>Palœosaurus</i> (fig. 153. <i>e</i>) has also been
+found in the Trias of the same region. Teeth of the latter, however,
+are found, along with remains of <i>Thecodontosaurus</i> (fig. 153,
+<i>d</i>), in a singular magnesian conglomerate near Bristol, which
+was originally believed to be of Permian age, but which appears to
+be undoubtedly Triassic.
+</p>
+
+<div class="center">
+<table border="0" width="509">
+<tr><td>
+<img src="images/fig152.jpg" width="505" height="258" alt="Fig. 152" />
+</td></tr>
+<tr><td class="left"><span class="image">
+Fig. 152.&mdash;Triassic Reptiles. <i>a</i>, Skull of <i>Nothosaurus
+mirabilis</i>, reduced in size&mdash;Muschelkalk, Germany; <i>b</i>,
+Tooth of <i>Simosaurus Gaillardoti</i>, of the natural
+size&mdash;Muschelkalk, Germany; <i>c</i>, Tooth of <i>Beladon
+Carolinensis</i>&mdash;Trias, America; <i>d</i>, Tooth of
+<i>Thecodontosaurus antiquus</i>, slightly enlarged&mdash;Britain;
+<i>e</i>, Tooth of <i>Palœosaurus platyodon</i>, of the
+natural size&mdash;Britain.
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+The Trias has also yielded the remains of the great marine reptiles
+which are often spoken of collectively as the "Enaliosaurians"
+or "Sea-lizards," and which will be more particularly spoken
+of in treating of the Jurassic period, of which they are more
+especially characteristic. In all these reptiles the limbs are
+flattened out, the digits being enclosed in a continuous skin,
+thus forming powerful swimming-paddles, resembling the "flippers"
+of the Whales and Dolphins both in their general structure and
+in function. The tail is also long, and adapted to act as a
+swimming-organ; and there can be no doubt but that these
+extraordinary and often colossal reptiles frequented the sea, and
+only occasionally came to the land. The Triassic Enaliosaurs belong
+to a group of which the later genus <i>Plesiosaurus</i> is the type
+(the <i>Sauropterygia</i>). One of the best known of the Triassic
+genera is <i>Nothosaurus</i> (fig. 152, <i>a</i>), in which the
+neck was long and bird-like, the jaws being immensely elongated,
+and carrying numerous powerful conical teeth implanted in distinct
+sockets. The teeth in <i>Simosaurus</i> (152, <i>b</i>) are of a
+similar nature; but the orbits are of enormous size, indicating
+eyes of corresponding dimensions, and perhaps pointing to the
+nocturnal habits of the animal. In the singular
+<a name="page_220"><span class="page">Page 220</span></a>
+<i>Placodus</i>,
+again, the teeth are in distinct sockets, but resemble those
+of many fishes in being rounded and obtuse (fig. 153), forming
+
+<span style="float: left; margin: 4px; width: 255px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig153.jpg" width="255" height="219" alt="Fig. 153" />
+<br />
+Fig. 153.&mdash;Under surface of the upper jaw and palate of
+<i>Placodus gigas</i>. Muschelkalk, Germany.
+</span>
+
+broad crushing plates adapted for the comminution of shell-fish.
+There is a row of these teeth all round the upper jaw proper,
+and a double series on the palate, but the lower jaw has only a
+single row of teeth. <i>Placodus</i> is found in the Muschelkalk,
+and the characters of its dental apparatus indicate that it was
+much more peaceful in its habits than its associates the Nothosaur
+and Simosaur.
+</p>
+
+<p class="indent">
+The Triassic rocks of South Africa and India have yielded the
+remains of some extraordinary Reptiles, which have been placed
+by Professor Owen in a separate order under the name of
+<i>Anomodontia</i>. The two principal genera of this group are
+<i>Dicynodon</i> and <i>Oudenodon</i>, both of which appear to
+have been large Reptiles, with well-developed limbs, organised
+for progression upon the dry land. In <i>Oudenodon</i> (fig.
+154, B) the jaws seem to have been wholly destitute of teeth, and
+must have been encased in a horny sheath, similar to that with
+which we are familiar in the beak of a Turtle. In <i>Dicynodon</i>
+(fig. 154, A), on the other hand, the front of the upper jaw
+and the whole of the lower jaw were destitute of teeth, and the
+front of the mouth must have constituted a kind of beak; but
+the upper jaw possessed on each side a single huge conical tusk,
+which is directed downwards, and must have continued to grow
+during the life of the animal.
+</p>
+
+<p class="indent">
+It may be mentioned that the above-mentioned Triassic sandstones of
+South Africa have recently yielded to the researches of Professor
+Owen a new and unexpected type of Reptile, which exhibits some
+of the structural peculiarities which we have been accustomed
+to regard as characteristic of the Carnivorous quadrupeds. The
+Reptile in question has been named <i>Cyanodraco</i>, and it is
+looked upon by its distinguished discoverer as the type of a new
+order, to which he has given the name of <i>Theriodontia</i>. The
+teeth of this singular form agree with those of the Carnivorous
+quadrupeds in consisting of three distinct groups&mdash;namely,
+front teeth or <i>incisors</i>, eye teeth or <i>canines</i>, and
+back teeth or <i>molars</i>. The canines
+<a name="page_221"><span class="page">Page 221</span></a>
+also are long and pointed,
+very much compressed, and having their lateral margins finely
+serrated, thus presenting a singular resemblance to the teeth
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 347px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig154.jpg" width="347" height="416" alt="Fig. 154" />
+<br />
+Fig. 154.&mdash;Triassic Anomodont Reptiles. A, Skull of
+<i>Dicynodon lacerticeps</i>, showing one of the great maxillary
+tusks; B, Skull of <i>Oudenodon Bainii</i>, showing the toothless,
+beak-like jaws. From the Trias of South Africa. (After Owen.)
+</span>
+</span>
+
+of the extinct "Sabre-toothed Tiger" (<i>Machairodus</i>). The
+bone of the upper arm (humerus) further shows some remarkable
+resemblances to the same bone in the Carnivorous Mammals. As
+has been previously noticed, Professor Owen is of opinion that
+some of the Reptilian remains of the Permian deposits will also
+be found to belong to this group of the "Theriodonts."
+</p>
+
+<p class="indent">
+Lastly, we find in the Triassic rocks the remains of Reptiles
+belonging to the great Mesozoic order of the <i>Deinosauria</i>.
+This order attains its maximum at a later period, and will be
+spoken of when the Jurassic and Cretaceous deposits come to be
+considered. The chief interest of the Triassic Reptiles of this
+group arises from the fact that they are known by their footprints
+as well as by their bones; and a question has arisen whether the
+supposed footprints of <i>birds</i> which occur in the Trias
+have not really been produced by Deinosaurs. This leads us,
+therefore, to speak at the same time as to the evidence which we
+have of the existence of the class of Birds during the Triassic
+period. No actual bones of any bird have as
+<a name="page_222"><span class="page">Page 222</span></a>
+yet been detected in any Triassic deposit; but we have tolerably
+clear evidence of their existence at this time in the form of
+<i>footprints</i>. The impressions in question are found in
+considerable numbers in certain red sandstones of the age of the
+Trias in the valley of the Connecticut River, in the United States.
+They vary much in size, and have evidently been produced by many
+different animals walking over long stretches of estuarine mud
+and sand exposed at low water. The footprints now under
+consideration form a double series of <i>single</i> prints, and
+therefore, beyond all question, are the tracks of a
+<i>biped</i>&mdash;that is, of an animal which walked upon two
+legs. No living animals, save Man and the Birds, walk habitually
+on two legs; and there is, therefore, a <i>primâ facie</i>
+presumption that the authors of these prints were Birds. Moreover,
+each impression consists of the marks of three toes turned
+forwards (fig. 155), and therefore are precisely such as might be
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 436px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig155.jpg" width="436" height="327" alt="Fig. 155" />
+<br />
+Fig. 155.&mdash;Supposed footprint of a Bird, from the Triassic
+Sandstones of the Connecticut River. The slab shows also numerous
+"rain-prints."
+</span>
+</span>
+
+produced by Wading or Cursorial Birds. Further, the impressions
+of the toes show exactly the same numerical progression in the
+number of the joints as is observable in living Birds&mdash;that is
+to say, the innermost of the three toes consists of three joints,
+the middle one of four, and the outer one of five joints. Taking
+this evidence collectively, it would have seemed, until lately,
+quite certain that these tracks could only have been formed by
+Birds. It has, however, been shown that the Deinosaurian Reptiles
+possess, in some cases at any rate, some singularly bird-like
+characters, amongst
+<a name="page_223"><span class="page">Page 223</span></a>
+which is the fact that
+the animal possessed the power of walking, temporarily at least,
+on its hind-legs, which were much longer and stronger than the
+fore-limbs, and which were sometimes furnished with no more than
+three toes. As the bones and teeth of Deinosaurs have been found
+in the Triassic deposits of North America, it may be regarded as
+certain that <i>some</i> of the bipedal tracks originally ascribed
+to Birds must have really been produced by these Reptiles. It seems
+at the same time almost a certainty that others of the three-toed
+impressions of the Connecticut sandstones were in truth produced
+by Birds, since it is doubtful if the bipedal mode of progression
+was more than an occasional thing amongst the Deinosaurs, and the
+greater number of the many known tracks exhibit no impressions
+of fore-feet. Upon the whole, therefore, we may, with much
+probability, conclude that the great class of Birds (<i>Aves</i>)
+was in existence in the Triassic period. If this be so, not only
+must there have been quite a number of different forms, but some
+of them must have been of very large size. Thus the largest
+footprints hitherto discovered in the Connecticut sandstones are
+22 inches long and 12 inches wide, with a proportionate length
+of stride. These measurements indicate a foot four times as large
+as that of the African Ostrich; and the animal which produced
+them&mdash;whether a Bird or a Deinosaur&mdash;must have been of
+colossal dimensions.
+</p>
+
+<p class="indent">
+Finally, the Trias completes the tale of the great classes of
+the Vertebrate sub-kingdom by presenting us with remains of the
+first known of the true Quadrupeds or <i>Mammalia</i>. These
+are at present only known by their teeth, or, in one instance,
+by one of the halves of the lower jaw; and these indicate minute
+Quadrupeds, which present greater affinities with the little Banded
+Anteater (<i>Myrmecobius fasciatus</i>, fig. 158) of Australia
+than with any other living form. If this conjecture be correct,
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 283px; vertical-align:bottom; text-align: center;
+  margin: 4px;">
+<img src="images/fig156.jpg" width="283" height="92" alt="Fig. 156" />
+<br />
+Fig. 156.&mdash;Lower jaw of <i>Dromatherium sylvestre</i>. Trias,
+North Carolina. (After Emmons.)
+</span>
+
+<span style="width: 186px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig157.jpg" width="186" height="107" alt="Fig. 157" />
+<br />
+Fig. 157.&mdash;<i>a</i>, Molar tooth of <i>Micro estes antiquus</i>,
+magnified; <i>b</i>, Crown of the same, magnified still further.
+Trias, Germany.
+</span>
+
+</span>
+
+these ancient Mammals belonged to the order of the Marsupials or
+Pouched Quadrupeds (<i>Marsupialia</i>), which
+<a name="page_224"><span class="page">Page 224</span></a>
+are now exclusively confined
+to the Australian province, South America, and the southern
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 524px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig158.jpg" width="524" height="278" alt="Fig. 158" />
+<br />
+Fig. 158.&mdash;The Banded Ant-eater (<i>Myrmecobius fasciatus</i>)
+of Australia.
+</span>
+</span>
+
+portion of North America. In the Old World, the only known Triassic
+Mammals belong to the genus <i>Microlestes</i>, and to the probably
+identical <i>Hypsiprymnopsis</i> of Professor Boyd Dawkins. The
+teeth of <i>Microlestes</i> (fig. 157) were originally discovered
+by Plieninger in 1847 in the "bone-bed" which is characteristic
+of the summit of the Rhætic series both in Britain and on the
+continent of Europe; and the known remains indicate two species.
+In Britain, teeth of <i>Microlestes</i> have been discovered
+by Mr Charles Moore in deposits of Upper Triassic age, filling
+a fissure in the Carboniferous limestone near Frome, in Somersetshire;
+and a molar tooth of <i>Hypsiprymnopsis</i> was found by Professor
+Boyd Dawkins in Rhætic marls below the "bone-bed" at Watchet,
+also in Somersetshire. In North America, lastly, there has been
+found in strata of Triassic age one of the branches of the lower
+jaw of a small Mammal, which has been described under the name of
+<i>Dromatherium sylvestre</i> (fig. 156). The fossil exhibits ten
+small molars placed side by side, one canine, and three incisors,
+separated by small intervals, and it indicates a small insectivorous
+animal, probably most nearly related to the existing
+<i>Myrmecobius</i>.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following list comprises a few of the more important sources of
+information as to the Triassic strata and their fossil
+contents:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Geology of Oxford and the Valley of the Thames.'
+  Phillips.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Memoirs of the Geological Survey of Great Britain and
+  Ireland.'</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Report on the Geology of Londonderry,' &amp;c. Portlock.</td></tr>
+<tr><td class="right" valign="top">
+  <a name="page_225"><span class="page">Page 225</span></a>
+  (4)</td>
+ <td>"On the Zone of Avicula contorta," &amp;c.&mdash;'Quart. Journ.
+  Geol. Soc.,' vol. xvi., 1860. Dr Thomas Wright.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>"On the Zones of the Lower Lias and the Avicula contorta
+  Zone"&mdash;'Quart. Journ. Geol. Soc.,' vol. xvii., 1861. Charles
+  Moore.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>"On Abnormal Conditions of Secondary Deposits," &amp;c.&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. xxiii., 1876-77. Charles Moore.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>'Geognostische Beschreibung des Bayerischen Alpengebirges.'
+  G&uuml;mbel.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>'Lethæa Rossica.' Pander.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>'Lethæa Geognostica.' Bronn.</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Petrefacta Germaniæ.' Goldfuss.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'Petrefaktenkunde.' Quenstedt.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>'Monograph of the Fossil Estheriæ'
+  (Palæontographical Society). Rupert Jones.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>"Fossil Remains of Three Distinct Saurian Animals,
+  recently discovered in the Magnesian Conglomerate near
+  Bristol"&mdash;'Trans. Geol. Soc.,' ser. 2, vol. v., 1840. Riley
+  and Stutchbury.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>'Die Saurier des Muschekalkes.' Von Meyer.</td></tr>
+<tr><td class="right" valign="top">(15)</td>
+ <td>'Beitr&auml;ge zur Palæontologie W&uuml;rttembergs.' Von
+  Meyer and Plieninger.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Manual of Palæontology.' Owen.</td></tr>
+<tr><td class="right" valign="top">(17)</td>
+ <td>'Odontography:' Owen.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>'Report on Fossil Reptiles' (British Association, 1841).
+  Owen.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>"On Dicynodon"&mdash;'Trans. Geol. Soc.,' vol. iii., 1845.
+  Owen.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>'Descriptive Catalogue of Fossil Reptilia and Fishes in the
+  Museum of the Royal College of Surgeons, England.'
+  Owen.</td></tr>
+<tr><td class="right" valign="top">(21)</td>
+ <td>"On Species of Labyrinthodon from Warwickshire"&mdash;'Trans.
+  Geol. Soc.,' ser. 2, vol. vi. Owen.</td></tr>
+<tr><td class="right" valign="top">(22)</td>
+ <td>"On a Carnivorous Reptile" (Cynodraco major),
+  &amp;c.&mdash;'Quart. Journ. Geol. Soc.,' vol. xxxii., 1876.
+  Owen.</td></tr>
+<tr><td class="right" valign="top">(23)</td>
+ <td>"On Evidences of Theriodonts in Permian Deposits,"
+  &amp;c.&mdash;'Quart. Journ. Geol. Soc.,' vol. xxxii., 1876.
+  Owen.</td></tr>
+<tr><td class="right" valign="top">(24)</td>
+ <td>"On the Stagonolepis Robertsoni," &amp;c.&mdash;'Quart. Journ.
+  Geol. Soc.,' vol. xv., 1859. Huxley.</td></tr>
+<tr><td class="right" valign="top">(25)</td>
+ <td>"On a New Specimen of Telerpeton Elginense"&mdash;'Quart. Journ.
+  Geol. Soc.,' vol. xxiii., 1866. Huxley.</td></tr>
+<tr><td class="right" valign="top">(26)</td>
+ <td>"On Hyperodapedon"&mdash;'Quart. Journ. Geol. Soc.,' vol. xxv.,
+  1869. Huxley.</td></tr>
+<tr><td class="right" valign="top">(27)</td>
+ <td>"On the Affinities between the Deinosaurian Reptiles and
+  Birds"&mdash;'Quart. Journ. Geol. Soc.,' vol. xxvi., 1870.
+  Huxley.</td></tr>
+<tr><td class="right" valign="top">(28)</td>
+ <td>"On the Classification of the Deinosauria,"
+  &amp;c.&mdash;'Quart. Journ. Geol. Soc.,' vol. xxvi., 1870.
+  Huxley.</td></tr>
+<tr><td class="right" valign="top">(29)</td>
+ <td>"Palæontologica Indica"&mdash;'Memoirs of the Geol.
+  Survey of India.'</td></tr>
+<tr><td class="right" valign="top">(30)</td>
+ <td>"On the Geological Position and Geographical Distribution of
+  the Dolomitic Conglomerate of the Bristol Area"&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. xxvi., 1870. R. Etheridge, sen.</td></tr>
+<tr><td class="right" valign="top">(31)</td>
+ <td>"Remains of Labyrinthodonta from the Keuper Sandstone of
+  Warwick"&mdash;'Quart. Journ. Geol. Soc.,' vol. xxx., 1874
+  Miall.</td></tr>
+<tr><td class="right" valign="top">(32)</td>
+ <td>'Manual of Geology.' Dana.</td></tr>
+<tr><td class="right" valign="top">(33)</td>
+ <td>'Synopsis of Extinct Batrachia and Reptilia of North America.'
+  Cope.</td></tr>
+<tr><td class="right" valign="top">(34)</td>
+ <td>'Fossil Footmarks.' Hitchcock.</td></tr>
+<tr><td class="right" valign="top">(35)</td>
+ <td>'Ichnology of New England.' Hitchcock.</td></tr>
+<tr><td class="right" valign="top">(36)</td>
+ <td>'Traité de Paléontologie
+  Végétale.' Schimper.</td></tr>
+<tr><td class="right" valign="top">(37)</td>
+ <td>'Histoire des Végétaux Fossiles.'
+  Brongniart.</td></tr>
+<tr><td class="right" valign="top">(38)</td>
+ <td>'Monographie der Fossilen Coniferen.' Gœppert.</td></tr>
+</table>
+
+<h3>
+<a name="page_226"><span class="page">Page 226</span></a>
+CHAPTER XVI.</h3>
+
+<p class="subtitle">
+THE JURASSIC PERIOD.
+</p>
+
+<p class="indent">
+Resting upon the Trias, with perfect conformity, and with an almost
+undeterminable junction, we have the great series of deposits which
+are known as the <i>Oolitic Rocks</i>, from the common occurrence
+in them of oolitic limestones, or as the <i>Jurassic Rocks</i>,
+from their being largely developed in the mountain-range of the
+Jura, on the western borders of Switzerland. Sediments of this
+series occupy extensive areas in Great Britain, on the continent
+of Europe, and in India. In North America, limestones and marls
+of this age have been detected in "the Black Hills, the Laramie
+range, and other eastern ridges of the Rocky Mountains; also over
+the Pacific slope, in the Uintah, Wahsatch, and Humboldt Mountains,
+and in the Sierra Nevada" (Dana); but in these regions their
+extent is still unknown, and their precise subdivisions have
+not been determined. Strata belonging to the Jurassic period
+are also known to occur in South America, in Australia, and in
+the Arctic zone. When fully developed, the Jurassic series is
+capable of subdivision into a number of minor groups, of which
+some are clearly distinguished by their mineral characters, whilst
+others are separated with equal certainty by the differences of
+the fossils that they contain. It will be sufficient for our
+present purpose, without entering into the more minute subdivisions
+of the series, to give here a very brief and general account of the
+main sub-groups of the Jurassic rocks, as developed in
+Britain&mdash;the arrangement of the Jura-formation of the continent
+of Europe agreeing in the main with that of England.
+</p>
+
+<p class="indent">
+I. THE LIAS.&mdash;The base of the Jurassic series of Britain is
+formed by the great calcareo-argillaceous deposit of the "Lias,"
+which usually rests conformably and almost inseparably upon the
+Rhætic beds (the so-called "White Lias"), and passes up,
+generally conformably, into the calcareous sandstones of the
+Inferior Oolite. The Lias is divisible into the three principal
+groups of the Lower, Middle, and Upper Lias, as under, and these
+in turn contain many well-marked "zones;" so that the Lias has
+some claims to be considered as an independent formation,
+equivalent to all the remaining Oolitic rocks. The <i>Lower
+Lias</i> (<i>Terrain Sinemurien</i> of D'Orbigny) sometimes
+attains a thickness of as much as 600 feet, and consists of a
+great series of bluish or greyish laminated clays,
+<a name="page_227"><span class="page">Page 227</span></a>
+alternating with thin bands of blue or grey
+limestone&mdash;the whole, when seen in quarries or cliffs from a
+little distance, assuming a characteristically striped and banded
+appearance. By means of particular species of <i>Ammonites</i>,
+taken along with other fossils which are confined to particular
+zones, the Lower Lias may be subdivided into several well-marked
+horizons. The <i>Middle Lias</i>, or <i>Marlstone Series</i>
+(<i>Terrain Liasien</i> of D'Orbigny), may reach a thickness
+of 200 feet, and consists of sands, arenaceous marls, and
+argillaceous limestones, sometimes with ferruginous beds. The
+<i>Upper Lias</i> (<i>Terrain Toarcien</i> of D'Orbigny) attains
+a thickness of 300 feet, and consists principally of shales below,
+passing upwards into arenaceous strata.
+</p>
+
+<p class="indent">
+II. THE LOWER OOLITES.&mdash;Above the Lias comes a complex series
+of partly arenaceous and argillaceous, but principally calcareous
+strata, of which the following are the more important groups:
+<i>a</i>, The <i>Inferior Oolite</i> (<i>Terrain Bajocien</i>
+of D'Orbigny), consisting of more than 200 feet of oolitic
+limestones, sometimes more or less sandy; <i>b</i>, The <i>Fuller's
+Earth</i>, a series of shales, clays, and marls, about 120 feet in
+thickness; <i>c</i>, The <i>Great Oolite</i> or <i>Bath Oolite</i>
+(<i>Terrain Bathonien</i> of D'Orbigny), consisting principally
+of oolitic limestones, and attaining a thickness of about 130
+feet. The well-known "Stonesfield Slates" belong to this horizon;
+and the locally developed "Bradford Clay," "Corn brash," and
+"Forest-marble" may be regarded as constituting the summit of
+this group.
+</p>
+
+<p class="indent">
+III. THE MIDDLE OOLITES.&mdash;The central portion of the Jurassic
+series of Britain is formed by a great argillaceous deposit,
+capped by calcareous strata, as follows: <i>a</i>, The <i>Oxford
+Clay</i> (<i>Terrain Callovien</i> and <i>Terrain Oxfordien</i> of
+D'Orbigny), consisting of dark-coloured laminated clays, sometimes
+reaching a thickness of 700 feet, and in places having its lower
+portion developed into a hard calcareous sandstone ("Kelloway
+Rock"); <i>b</i>, The Coral-Rag (<i>Terrain Corallien</i> of
+D'Orbigny, "Nerinean Limestone" of the Jura, "Diceras Limestone"
+of the Alps), consisting, when typically developed, of a central
+mass of oolitic limestone, underlaid and surmounted by calcareous
+grits.
+</p>
+
+<p class="indent">
+IV. THE UPPER OOLITES.&mdash;<i>a</i>, The base of the Upper Oolites
+of Britain is constituted by a great thickness (600 feet or more)
+of laminated, sometimes carbonaceous or bituminous clays, which are
+known as the <i>Kimmeridge Clay</i> (<i>Terrain Kimméridgien</i>
+of D'Orbigny); <i>b</i>, The <i>Portland Beds</i> (<i>Terrain
+Portlandien</i> of D'Orbigny) succeed the Kimmeridge clay, and
+consist inferiorly of sandy beds surmounted by oolitic limestones
+<a name="page_228"><span class="page">Page 228</span></a>
+("Portland Stone"), the whole series attaining
+a thickness of 150 feet or more, and containing marine fossils;
+<i>c</i>, The <i>Purbeck</i> Beds are apparently peculiar to Great
+Britain, where they form the summit of the entire Oolitic series,
+attaining a total thickness of from 150 to 200 feet. The Purbeck
+beds consist of arenaceous, argillaceous, and calcareous strata,
+which can be shown by their fossils to consist of a most remarkable
+alternation of fresh-water, brackish-water, and purely marine
+sediments, together with old land-surfaces, or vegetable soils,
+which contain the upright stems of trees, and are locally known as
+"Dirt-beds."
+</p>
+
+<p class="indent">
+One of the most important of the Jurassic deposits of the continent
+of Europe, which is believed to be on the horizon of the Coral-rag
+or of the lower part of the Upper Oolites, is the "<i>Solenhofen
+Slate</i>" of Bavaria, an exceedingly fine-grained limestone,
+which is largely used in lithography, and is celebrated for the
+number and beauty of its organic remains, and especially for
+those of Vertebrate animals.
+</p>
+
+<p class="indent">
+The subjoined sketch-section (fig. 159) exhibits in a diagrammatic
+form the general succession of the Jurassic rocks of Britain.
+</p>
+
+<p class="indent">
+Regarded as a whole, the Jurassic formation is essentially marine;
+and though remains of drifted plants, and of insects and other
+air-breathing animals, are not uncommon, the fossils of the formation
+are in the main marine. In the Purbeck series of Britain,
+anticipatory of the great river-deposit of the Wealden, there are
+fresh-water, brackish-water, and even terrestrial strata, indicating
+that the floor of the Oolitic ocean was undergoing upheaval, and
+that the marine conditions which had formerly prevailed were nearly
+at an end. In places also, as in Yorkshire and Sutherlandshire,
+are found actual beds of coal: but the great bulk of the formation
+is an indubitable sea-deposit; and its limestones, oolitic as
+they commonly are, nevertheless are composed largely of the
+comminuted skeletons of marine animals. Owing to the enormous
+number and variety of the organic remains which have been yielded
+by the richly fossiliferous strata of the Oolitic series, it will
+not be possible here to do more than to give an outline-sketch
+of the principal forms of life which characterise the Jurassic
+period as a whole. It is to be remembered, however, that every
+minor group of the Jurassic formation has its own peculiar fossils,
+and that by the labours of such eminent observers as Quenstedt,
+Oppel, D'Orbigny, Wright, De la Beche, Tate, and others, the
+entire series of Jurassic sediments admits of a more complete
+and more elaborate subdivision into zones
+<a name="page_229"><span class="page">Page 229</span></a>
+characterised by special life-forms than has as yet been found
+practicable in the case of any other rock-series.
+</p>
+
+<div class="center">
+<table border="0" width="545">
+<tr><td><span class="image">GENERALIZED SECTION OF THE JURASSIC
+ROCKS OF ENGLAND.</span></td></tr>
+<tr><td><span class="image">Fig. 159.</span></td></tr>
+<tr><td>
+<img src="images/fig159.jpg" width="541" height="708" alt="Fig. 159" />
+</td></tr>
+</table>
+</div>
+
+<p class="indent">
+The <i>plants</i> of the Jurassic period consist principally of
+Ferns, Cycads, and Conifers&mdash;agreeing in this respect,
+<a name="page_230"><span class="page">Page 230</span></a>
+therefore, with those of the preceding
+Triassic formation. The <i>Ferns</i> are very abundant, and
+belong partly to old and partly to new genera. The <i>Cycads</i>
+are also very abundant, and, on the whole, constitute the most
+marked feature of the Jurassic vegetation, many genera of this
+group being known (<i>Pterophyllum, Otozamites, Zamites,
+Crossozamia, Williamsonia, Bucklandia,</i> &amp;c.) The so-called
+"dirt-bed" of the Purbeck series consists of an ancient soil,
+in which stand erect the trunks of Conifers and the silicified
+stools of Cycads of the genus <i>Mantellia</i> (fig.160). The
+<i>Coniferœ</i> of the Jurassic are represented by various
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 301px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig160.jpg" width="301" height="204" alt="Fig. 160" />
+<br />
+Fig. 160.&mdash;<i>Mantellia</i> (<i>Cycadeoidea</i>)
+<i>megalophylla</i>, a Cycad from the Purbeck "dirt-bed." Upper
+Oolites, England.
+</span>
+</span>
+
+forms more or less nearly allied to the existing
+<i>Araucariœ</i>; and these are known not only by their
+stems or branches, but also in some cases by their cones. We meet,
+also, with the remains of undoubted Endogenous plants, the most
+important of which are the fruits of forms allied to the existing
+Screw-pines (<i>Pandaneœ</i>), such as <i>Podocarya</i> and
+<i>Kaidacarpum</i>. So far, however, no remains of Palms have been
+found; nor are we acquainted with any Jurassic plants which could
+be certainly referred to the great "Angiospermous" group of the
+Exogens, including the majority of our ordinary plants and trees.
+</p>
+
+<p class="indent">
+Amongst animals, the <i>Protozoans</i> are well represented in
+the Jurassic deposits by numerous <i>Foraminifers</i> and
+<i>Sponges</i>; as are the <i>Cœlenterates</i> by numerous
+<i>Corals</i>. Remains of these last-mentioned organisms are
+extremely abundant in some of the limestones of the formation,
+such as the "Coral-rag" and the Great Oolite; and the former of
+these may fairly be considered as an ancient "reef." The <i>Rugose
+Corals</i> have not hitherto been detected in the Jurassic rocks;
+and the "<i>Tabulate Corals</i>," so-called, are represented
+only by examples of the modern genus <i>Millepora</i>. With this
+<a name="page_231"><span class="page">Page 231</span></a>
+exception, all the Jurassic Corals belong to
+the great group which predominates in recent seas (<i>Zoantharia
+sclerodermata</i>); and the majority belong to the important
+reef-building family of the "Star-corals" (<i>Astrœidoe</i>).
+The form here figured (<i>Thecosmilia annularis</i>, fig. 161) is
+one of the characteristic species of the Coral-rag.
+</p>
+
+<div class="center">
+<table border="0" width="435">
+<tr><td>
+<img src="images/fig161.jpg" width="431" height="342" alt="Fig. 161" />
+</td></tr>
+<tr><td class="center"><span class="image">
+Fig. 161.&mdash;<i>Thecosmilia annularis</i>, Coral-rag, England.
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+The <i>Echinoderms</i> are very numerous and abundant fossils
+in the Jurassic series, and are represented by Sea-lilies,
+Sea-urchins, Star-fishes, and Brittle-stars. The <i>Crinoids</i>
+are still common, and some of the limestones of the series are
+largely composed of the <i>débris</i> of these organisms.
+Most of the Jurassic forms resemble those with which we are already
+familiar, in having the body permanently attached to some foreign
+object by means of a longer or shorter jointed stalk or "column."
+One of the most characteristic Jurassic genera of these "stalked"
+Crinoids (though not exclusively confined to this period) is
+<i>Pentacrinus</i> (fig. 162). In this genus, the column is
+five-sided, with whorls of "side-arms;" and the arms are long,
+slender, and branched. The genus is represented at the present
+day by the beautiful "Medusa-head Pentacrinite" (<i>Pentacrinus
+caput-medusœ</i>). Another characteristic Oolitic genus is
+<i>Apiocrinus</i>, comprising the so-called "Pear Encrinites." In
+this group the column is long and rounded, with a dilated base,
+and having its uppermost joints expanded so as to form, with the
+cup itself, a pear-shaped mass, from the summit of which spring
+the comparatively short arms. Besides the
+<a name="page_232"><span class="page">Page 232</span></a>
+"stalked" Crinoids, the
+Jurassic rocks have yielded the remains of the higher group of the
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 426px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig162.jpg" width="426" height="743" alt="Fig. 162" />
+<br />
+Fig. 162.&mdash;<i>Pentacrinus fasciculos</i>, Lias. The left-hand
+figure shows a few or the joints of the column; the middle figure
+shows the arms, and the summit of the column with its side-arms;
+and the right-hand figure shows the articulating surface of one
+of the column-joints.
+</span>
+</span>
+
+"free" Crinoids, such as <i>Saccosoma</i>. These forms resemble the
+existing "Feather-stars" (<i>Comatula</i>) in being attached when
+<a name="page_233"><span class="page">Page 233</span></a>
+young to some foreign body by means of a
+jointed stem, from which they detach themselves when fully grown
+to lead an independent existence. In this later stage of their
+life, therefore, they closely resemble the Brittle-stars in
+appearance. True Star-fishes (<i>Asteroids</i>) and Brittle-stars
+(<i>Ophiuroids</i>) are abundant in the Jurassic rocks, and the
+Sea-urchins (<i>Echinoids</i>) are so numerous and so well
+preserved as to constitute quite a marked feature of some beds
+of the series. All the Oolitic urchins agree with the modern
+<i>Echinoids</i> in having the shell composed of no more than
+twenty rows of plates. Many different genera are known, and a
+characteristic species of the Middle Oolites (<i>Hemicidaris
+crenularis</i>, fig. 163) is here figured.
+</p>
+
+<div class="center">
+<table border="0" width="535">
+<tr><td>
+<img src="images/fig163.jpg" width="531" height="222" alt="Fig. 163" />
+</td></tr>
+<tr><td class="center"><span class="image">
+Fig. 163.&mdash;<i>Hemicidaris crenularis</i>, showing the great
+tubercles on which the spines were supported. Middle Oolites.
+</span></td></tr>
+</table>
+</div>
+
+<p class="indent">
+Passing over the <i>Annelides</i>, which, though not uncommon,
+are of little special interest, we come to the <i>Articulates</i>,
+which also require little notice. Amongst the <i>Crustaceans</i>,
+whilst the little Water-fleas (<i>Ostracoda</i>) are still abundant,
+the most marked feature is the predominance which is now assumed
+by the <i>Decapods</i>&mdash;the highest of the known groups of
+the class. True Crabs (<i>Brachyura</i>) are by no means unknown;
+but the principal Oolitic Decapods belonged to the "Long-tailed"
+group (<i>Macrura</i>), of which the existing Lobsters, Prawns,
+and Shrimps are members. The fine-grained lithographic slates of
+Solenhofen are especially famous as a depot for the remains of
+these Crustaceans, and a characteristic species from this locality
+(<i>Eryon arctiformis</i>, fig. 164) is here represented. Amongst
+the air-breathing <i>Articulates</i>, we meet in the Oolitic
+rocks with the remains of Spiders (<i>Arachnida</i>), Centipedes
+(<i>Myriapoda</i>), and numerous true Insects (<i>Insecta</i>).
+In connection with the last-mentioned of these groups, it is of
+interest to note the occurrence of the oldest known fossil
+Butterfly&mdash;the <i>Palœontina Oolitica</i> of the
+Stonesfield slate&mdash;the
+<a name="page_234"><span class="page">Page 234</span></a>
+relationships of which appear to be with some of the living
+Butterflies of Tropical America.
+</p>
+
+<p class="indent">
+Coming to the <i>Mollusca</i>, the <i>Polyzoans</i>, numerous
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 321px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig164.jpg" width="321" height="452" alt="Fig. 164" />
+<br />
+Fig. 164.&mdash;<i>Eryon arctiformis</i>, a "Long-tailed Decapod,"
+from the Middle Oolites (Solenhofen Slate).
+</span>
+</span>
+
+and beautiful as they are, must be at once dismissed; but the
+<i>Brachiopods</i> deserve a moment's attention. The Jurassic
+Lamp-shells (fig. 165) do not fill by any means such a predominant
+place in the marine fauna of the period, as in many Palæozoic
+deposits, but they are still individually numerous. The two ancient
+genera <i>Leptœna</i> (fig. 165, <i>a</i>) and <i>Spirifera</i>
+(fig. 165, <i>b</i>), dating the one from the Lower and the other
+from the Upper Silurian, appear here for the last time upon the
+scene, but they have not hitherto been recognised in deposits later
+than the Lias. The great majority of the Jurassic <i>Brachiopods</i>,
+however, belong to the genera <i>Terebratula</i> (fig. 165, <i>c,
+e, f</i>) and <i>Rhynchonella</i> (fig. 165. <i>d</i>), both of
+which are represented by living forms at the present day. The
+<i>Terebratulœ</i>, in particular, are very abundant, and
+the species are often confined to special horizons in the series.
+</p>
+
+<p class="indent">
+Remains of <i>Bivalves</i> (<i>Lamellibranchiata</i>) are very
+<a name="page_235"><span class="page">Page 235</span></a>
+numerous in the
+Jurassic deposits, and in many cases highly characteristic.
+In the marine beds of the Oolites, which constitute
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 520px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig165.jpg" width="520" height="370" alt="Fig. 165" />
+<br />
+Fig. 165.&mdash;Jurassic
+Brachiopod. <i>a. Leptœna Liassica</i>, enlarged, the small
+cross below the figure indicating the true size of the
+shell&mdash;Lias; <i>b, Spirifera rostrata</i>, Lias;
+<i>c, Terebratula quadrifida</i>, Lias; <i>d, d', Rhynchonella
+varians</i>, Fulter's Earth and Kelloway Rock; <i>e, Terebratula
+sphœroidalis</i>, Inferior Oolite; <i>f, Terebratula
+digona</i>, Bradford Clay, Forest-marble, and Great Oolite.
+(After Davidson).
+</span>
+</span>
+
+by far the greater portion of the whole formation, the Bivalyes
+are of course marine, and belong to such genera as <i>Trigonia,
+Lima, Pholadomya, Cardinia, Avicula, Hippopodium</i>, &amp;c.;
+but in the Purbeck beds, at the summit of the series, we find
+bands of Oysters alternating with strata containing fresh-water
+or brackish-water Bivalves, such as <i>Cyrenœ</i> and
+<i>Corbulœ</i>. The predominant Bivalves of the Jurassic,
+however, are the <i>Oysters</i>, which occur under many forms,
+and often in vast numbers, particular species being commonly
+restricted to particular horizons. Thus of the true Oysters,
+<i>Ostrea distorta</i> is characteristic of the Purbeck series,
+where it forms a bed twelve feet in thickness, known locally as
+the "Cinder-bed;" <i>Ostrea expansa</i> abounds in the Portland
+beds; <i>Ostrea deltoidea</i> is characteristic of the Kimmeridge
+clay; <i>Ostrea gregaria</i> predominates in the Coral-rag;
+<i>Ostrea acuminata</i> characterises the small group of the
+Fuller's Earth; whilst the plaited <i>Ostrea Marshii</i> (fig.
+166) is a common shell in the Lower and Middle Oolites. Besides
+the more typical Oysters, the Oolitic rocks abound in examples
+of the singularly unsymmetrical forms belonging
+<a name="page_236"><span class="page">Page 236</span></a>
+to the genera <i>Exogyra</i> and <i>Gryphœa</i> (fig. 167).
+In the former of these are included Oysters with the beaks
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 228px; vertical-align:bottom; text-align: center;
+  margin: 4px;">
+<img src="images/fig166.jpg" width="228" height="206" alt="Fig. 166" />
+<br />
+Fig. 166.&mdash;<i>Ostrea Marshii</i>. Middle and Lower Oolites.
+</span>
+
+<span style="width: 255px; vertical-align:bottom; text-align: center;
+  margin: 4px;">
+<img src="images/fig167.jpg" width="255" height="194" alt="Fig. 167" />
+<br />
+Fig. 167.&mdash;<i>Gryphœa incurva</i>. Lias.
+</span>
+
+</span>
+
+"reversed"&mdash;that is to say, turned towards the hinder part
+of the shell; whilst in the latter are Oysters in which the lower
+valve of the shell is much the largest, and has a large incurved
+beak, whilst the upper valve is small and concave. One of the
+most characteristic <i>Exogyrœ</i> is the <i>E.
+Virgula</i> of the Oxford Clay, and of the same horizon on the
+Continent; and the <i>Gryphœa incurva</i> (fig. 167) is
+equally abundant in, and characteristic of, the formation of
+the Lias. Lastly, we may notice the extraordinary shells
+belonging to the genus <i>Diceras</i> (fig. 168), which are
+
+<span style="float: left; margin: 4px; width: 254px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig168.jpg" width="242" height="215" alt="Fig. 168" />
+<br />
+Fig. 168.&mdash;<i>Diceras arietina</i>. Middle Oolite.
+</span>
+
+exclusively confined to the Middle Oolites. In this formation
+in the Alps they occur in such abundance as to give rise to the
+name of "Calcaire &agrave; Dicerates," applied to beds of the
+same age as the Coral-rag of Britain. The genus <i>Diceras</i>
+belongs to the same family as the "Thorny Clams" (Chama) of the
+present day&mdash;the shell being composed of nearly equally-sized
+valves, the beaks of which are extremely prominent and twisted
+into a spiral. The shell was attached to some foreign body by
+the beak of one of its valves.
+</p>
+
+<p class="indent">
+Amongst the Jurassic Univalves (<i>Gasteropoda</i>) there are
+many examples of the ancient and long-lived <i>Pleurotomaria</i>;
+but on the whole the Univalves begin to have a modern aspect.
+The round-mouthed ("holostomatous"), vegetable-eating
+<a name="page_237"><span class="page">Page 237</span></a>
+Sea-snails, such as the Limpets (<i>Patellidœ</i>), the Nerites
+(<i>Nerita</i>), the <i>Turritellœ, Chemnitziœ</i>, &amp;c.,
+still hold a predominant place. The two most noticeable genera of
+this group are <i>Cerithium</i> and <i>Nerinœa</i>&mdash;the
+former of these attaining great importance in the Tertiary and Recent
+seas, whilst the latter (fig. 169) is highly characteristic of the
+Jurassic series, though not exclusively confined to it. One of the
+
+<span style="float: right; margin: 4px; width: 254px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig169.jpg" width="209" height="245" alt="Fig. 169" />
+<br />
+Fig. 169.&mdash;<i>Nerinœa Goodhallii</i>, one-fourth of the
+natural size. The left-hand figure shows the appearance presented
+by the shell when vertically divided. Coral-rag, England.
+</span>
+
+limestones of the Jura, believed to be of the age of the Coral-rag
+(Middle Oolite) of Britain, abounds to such an extent in the turreted
+shells of <i>Nerinœa</i> as to have gained the name of "Calcaire
+&agrave; Nérinées." In addition to forms such as the
+preceding, we now for the first time meet, in any force, with the
+Carnivorous Univalves, in which the mouth of the shell is notched or
+produced into a canal, giving rise to the technical name of
+"siphonostomatous" applied to the shell. Some of the carnivorous
+forms belong to extinct types, such as the <i>Purpuroidea</i> of the
+Great Oolite; but others are referable to well-known existing genera.
+Thus we meet here with species of the familiar groups of the Whelks
+(<i>Buccinum</i>), the Spindle-shells (<i>Fusus</i>), the Spider-shells
+(<i>Pteroceras</i>), <i>Murex, Rostellaria</i>, and others which are
+not at present known to occur in any earlier formation.
+</p>
+
+<p class="indent">
+Amongst the Wing-shells (<i>Pteropoda</i>), it is sufficient
+to mark the final appearance in the Lias of the ancient genus
+<i>Conularia</i>.
+</p>
+
+<p class="indent">
+Lastly, the order of the <i>Cephalopoda</i>, in both its
+Tetrabranchiate and Dibranchiate sections, undergoes a vast
+development in the Jurassic period. The old and comparatively
+simple genus <i>Nautilus</i> is still well represented, one
+species being very similar to the living Pearly Nautilus (<i>N.
+Pompilius</i>); but the <i>Orthocerata</i> and <i>Goniatites</i>
+of the Trias have finally disappeared; and the great majority
+of the Tetrabranchiate forms are referable to the comprehensive
+genus <i>Ammonites</i>, with its many sub-genera and its hundreds
+of recorded species. The shell in <i>Ammonites</i> is in the
+form of a flat spiral, all the coils of which are in contact
+(figs. 170 and 171). The innermost whorls of the shell are more
+or less concealed; and the body-chamber is elongated and narrow,
+rather than expanded towards the mouth. The tube or siphuncle
+<a name="page_238"><span class="page">Page 238</span></a>
+which runs through the air-chambers is placed on the dorsal or
+<i>convex</i> side of the shell; but the principal character
+which distinguishes <i>Ammonites</i> from <i>Goniatites</i> and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 480px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig170.jpg" width="480" height="312" alt="Fig. 170" />
+<br />
+Fig. 170.&mdash;<i>Ammonites Humphresianus</i>. Inferior Oolite.
+</span>
+</span>
+
+<i>Ceratites</i> is the wonderfully complex manner in which the
+<i>septa</i>, or partitions between the air-chambers, are folded and
+undulated. To such an extent does this take place, that the edges
+of the septa, when exposed by the removal of the shell-substance,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 403px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig171.jpg" width="403" height="288" alt="Fig. 171" />
+<br />
+Fig. 171.&mdash;<i>Ammonites bifrons</i>. Lias.
+</span>
+</span>
+
+present in an exaggerated manner the appearance exhibited by
+an elaborately-dressed shirt-frill when viewed edgewise. The
+species of <i>Ammonites</i> range from the Carboniferous to the
+Chalk; but they have not been found in
+<a name="page_239"><span class="page">Page 239</span></a>
+deposits older than the Secondary, in any region except India;
+and they are therefore to be regarded as essentially Mesozoic
+fossils. Within these limits, each formation is characterised
+by particular species, the number of individuals being often
+very great, and the size which is sometimes attained being
+nothing short of gigantic. In the Lias, particular species of
+<i>Ammonites</i> may succeed one another regularly, each having
+a more or less definite horizon, which it does not transgress.
+It is thus possible to distinguish a certain number of zones,
+each characterised by a particular Ammonite, together with
+other associated fossils. Some of these zones are very
+persistent and extend over very wide areas, thus affording
+valuable aid to the geologist in his determination of rocks.
+It is to be remembered, however, that there are other species
+which are not thus restricted in their vertical range, even
+in the same formations in which definite zones occur.
+</p>
+
+<p class="indent">
+The Cuttle-fishes or <i>Dibranchiate Cephalopods</i> constitute a
+feature in the life of the Jurassic period little less conspicuous
+and striking than that afforded by the multitudinous and varied
+chambered shells of the <i>Ammonitidœ</i>. The remains by
+which these animals are recognised are necessarily less perfect, as
+a rule, than those of the latter, as no external shell is present
+(except in rare and more modern groups), and the internal skeleton
+is not necessarily calcareous. Nevertheless,we have an ample
+record of the Cuttle-fishes of the Jurassic period, in the shape
+of the fossilised jaws or beak, the ink-bag, and, most commonly
+of all, the horny or calcareous structure which is embedded in
+the soft tissues, and is variously known as the "pen" or "bone."
+The beaks of Cuttle-fishes, though not abundant, are sufficiently
+plentiful to have earned for themselves the general title of
+"Rhyncholites;" and in their form and function they resemble the
+horny, parrot-like beak of the existing Cephalopods. The ink-bag
+or leathery sac in which the Cuttle-fishes store up the black
+pigment with which they obscure the water when attacked, owes its
+preservation to the fact that the colouring-matter which it contains
+is finely-divided carbon, and therefore nearly indestructible except
+by heat. Many of these ink-bags have been found in the Lias; and
+the colouring-matter is sometimes so well preserved that it has
+been, as an experiment, employed in painting as a fossil "sepia."
+The "pens" of the Cuttle-fishes are not commonly preserved, owing
+to their horny consistence, but they are not unknown. The form
+here figured (<i>Beloteuthis subcostata</i>, fig. 172) belonged
+to an old type essentially similar to our modern Calamaries, the
+skeleton of which consists of a horny shaft
+<a name="page_240"><span class="page">Page 240</span></a>
+and two lateral wings,
+somewhat like a feather in general shape. When, on the other
+
+<span style="float: left; margin: 4px; width: 123px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig172.jpg" width="123" height="306" alt="Fig. 172" />
+<br />
+Fig. 172.&mdash;<i>Beloteuthis subcostata</i> Jurassic (Lias).
+</span>
+
+hand, the internal skeleton is calcareous, then it is very easily
+preserved in a fossil condition; and the abundance of remains of
+this nature in the Secondary rocks, combined with their apparent
+total absence in Palæozoic strata, is a strong presumption in
+favour of the view that the order of the Cuttle-fishes did not
+come into existence till the commencement of the Mesozoic period.
+The great majority of the skeletons of this kind which are found
+in the Jurassic rocks belong to the great extinct family of the
+"Belemnites" (<i>Belemnitidoa</i>), which, so far as known, is
+entirely confined to rocks of Secondary age. From its pointed,
+generally cylindro-conical form, the skeleton of the Belemnite is
+popularly known as a "thunderbolt". (fig. 173, C). In its perfect
+condition&mdash;in which it is, however, rarely obtainable&mdash;the
+skeleton consists of a chambered conical shell (the "phragmacone"),
+the partitions between the chambers of which are pierced by a
+marginal tube or "siphuncle." This conical shell&mdash;curiously
+similar in its structure to the <i>external</i> shell of the
+Nautilus&mdash;is extended forwards into a horny "pen," and is sunk
+in a corresponding conical pit (fig. 173, B), excavated in the
+substance of a nearly cylindrical fibrous body or "guard," which
+projects backwards for a longer or shorter distance, and is the
+part most usually found in a fossil condition. Many different
+kinds of <i>Belemnites</i> are known, and their guards literally
+swarm in many parts of the Jurassic series, whilst some specimens
+attain very considerable dimensions. Not only is the internal
+skeleton known, but specimens of <i>Belemnites</i> and the nearly
+allied <i>Belemnoteuthis</i> have been found in some of the
+fine-grained sediments of the Jurassic formation, from which much
+has been learnt even as to the anatomy of the soft parts of the
+animal. Thus we know that the Belemnites were in many respects
+comparable with the existing Calamaries or Squids, the body being
+furnished with lateral fins, and the head carrying a circle of ten
+"arms," two of which were longer than the others (fig. 173, A).
+The suckers on the arms were provided, further, with horny hooks;
+there was a large ink-sac; and the mouth was armed with horny
+mandibles resembling in shape the beak of a parrot.
+</p>
+
+<p class="indent">
+Coming next to the <i>Vertebrates</i>, we find that the Jurassic
+<a name="page_241"><span class="page">Page 241</span></a>
+<i>Fishes</i> are still represented by <i>Ganoids</i> and
+<i>Placoids</i>. The Ganoids, however, unlike the old forms, now
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 485px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig173.jpg" width="485" height="434" alt="Fig. 173" />
+<br />
+Fig. 173.&mdash;A, Restoration of the animal of the Belemnite; B,
+Diagram showing the complete skeleton of a Belemnite, consisting
+of the chambered phragmacone (<i>a</i>), the guard (<i>b</i>),
+and the horny pen (<i>c</i>); C, Specimen of <i>Belemnites
+canaliculatus</i>, from the Inferior Oolite. (After Phillips.)
+</span>
+</span>
+
+for the most part possess nearly or quite symmetrical ("homocercal")
+tails. A characteristic genus is <i>Tetragonolepis</i> (fig. 174),
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig174.jpg" width="515" height="220" alt="Fig. 174" />
+<br />
+Fig. 174.&mdash;<i>Tetragonolepis</i> (restored), and scales of the
+same. Lias.
+</span>
+</span>
+
+with its deep compressed body, its rhomboidal, closely-fitting
+scales, and its single long dorsal fin. Amongst the <i>Placoids</i>
+<a name="page_242"><span class="page">Page 242</span></a>
+the teeth of true Sharks (<i>Notidanus</i>) occur for the first
+time; but by far the greater number of remains referable to this
+group are still the fin-spines and teeth of "Cestracionts,"
+resembling the living Port-Jackson Shark. Some of these teeth are
+pointed (<i>Hybodus</i>); but others are rounded, and are adapted
+for crushing shell-fish. Of these latter, the commonest are the
+teeth of <i>Acrodus</i> (fig. 175), of which the hinder ones are
+
+<span style="float: left; margin: 4px; width: 254px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig175.jpg" width="278" height="107" alt="Fig. 175" />
+<br />
+Fig. 175.&mdash;Tooth of <i>Acrodus nobilis</i>. Lias.
+</span>
+
+of an elongated form, with a rounded surface, covered with fine
+transverse striæ proceeding from a central longitudinal line.
+From their general form and striation, and their dark colour, these
+teeth are commonly called "fossil leeches" by the quarrymen.
+</p>
+
+<p class="indent">
+The Amphibian group of the <i>Labyrinthodonts</i>, which was
+so extensively developed in the Trias, appears to have become
+extinct, no representative of the order having hitherto been
+detected in rocks of Jurassic age.
+</p>
+
+<p class="indent">
+Much more important than the Fishes of the Jurassic series are
+the <i>Reptiles</i>, which are both very numerous, and belong to
+a great variety of types, some of these being very extraordinary
+in their anatomical structure. The predominant group is that
+of the "Enaliosaurs" or "Sea-lizards," divided into two great
+orders, represented respectively by the <i>Ichthyosaurus</i>
+and the <i>Plesiosaurus</i>.
+</p>
+
+<p class="indent">
+The <i>Ichthyosauri</i> or "Fish-Lizards" are exclusively Mesozoic
+in their distribution, ranging from the Lias to the Chalk, but
+abounding especially in the former. They were huge Reptiles, of
+a fish-like form, with a hardly conspicuous neck (fig. 176),
+and probably possessing a simply smooth or wrinkled skin, since
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 498px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig176.jpg" width="498" height="122" alt="Fig. 176" />
+<br />
+Fig. 176.&mdash;<i>Ichthyosaurus communis</i>. Lias.
+</span>
+</span>
+
+no traces of scales or bony integumentary plates have ever been
+discovered. The tail was long, and was probably furnished at its
+extremity with a powerful expansion of the skin, constituting a
+tail-fin similar to that possessed by the Whales. The limbs are
+also like those of
+<a name="page_243"><span class="page">Page 243</span></a>
+Whales in the essentials
+of their structure, and in their being adapted to act as
+swimming-paddles. Unlike the Whales, however, the Ichthyosaurs
+possessed the hind-limbs as well as the fore-limbs, both pairs
+having the bones flattened out and the fingers completely
+enclosed in the skin, the arm and leg being at the same time
+greatly shortened. The limbs are thus converted into efficient
+"flippers," adapting the animal for an active existence in the
+sea. The different joints of the backbone (vertebræ) also
+show the same adaptation to an aquatic mode of life, being
+hollowed out at both ends, like the biconcave vertebræ
+of Fishes. The spinal column in this way was endowed with the
+flexibility necessary for an animal intended to pass the
+greater part of its time in water. Though the <i>Ichthyosaurs</i>
+are undoubtedly marine animals, there is, however, reason to
+believe that they occasionally came on shore, as they possess
+a strong bony arch, supporting the fore-limbs, such as would
+permit of partial, if laborious, terrestrial progression. The
+head is of enormous size, with greatly prolonged jaws, holding
+numerous powerful conical teeth lodged in a common groove. The
+nature of the dental apparatus is such as to leave no doubt as to
+the rapacious and predatory habits of the Ichthyosaurs&mdash;an
+inference which is further borne out by the examination of their
+petrified droppings, which are known to geologists as "coprolites,"
+and which contain numerous fragments of the bones and scales
+of the Ganoid fishes which inhabited the same seas. The orbits
+are of huge size; and as the eyeball was protected, like that
+of birds, by a ring of bony plates in its outer coat, we even
+know that the pupils of the eyes were of correspondingly large
+dimensions. As these bony plates have the function of protecting the
+eye from injury under sudden changes of pressure in the surrounding
+medium, it has been inferred, with great probability, that the
+Ichthyosaurs were in the habit of diving to considerable depths
+in the sea. Some of the larger specimens of <i>Ichthyosaurus</i>
+which have been discovered in the Lias indicate an animal of
+from 20 to nearly 40 feet in length; and many species are known
+to have existed, whilst fragmentary remains of their skeletons
+are very abundant in some localities. We may therefore safely
+conclude that these colossal Reptiles were amongst the most
+formidable of the many tyrants of the Jurassic seas.
+</p>
+
+<p class="indent">
+The <i>Plesiosaurus</i> (fig. 177) is another famous Oolitic
+Reptile, and, like the preceding, must have lived mainly or
+exclusively in the sea. It agrees with the Ichthyosaur in some
+important features of its organisation, especially in the fact
+that both pairs of limbs are converted into "flippers" or
+<a name="page_244"><span class="page">Page 244</span></a>
+swimming-paddles,
+whilst the skin seems to have been equally destitute
+of any scaly or bony investiture. Unlike the <i>Ichthyosaur</i>,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig177.jpg" width="508" height="299" alt="Fig. 177" />
+<br />
+Fig. 177.&mdash;<i>Plesiosaurus dolichodeirus</i>, restored. Lias.
+</span>
+</span>
+
+however, the Plesiosaur had the paddles placed
+far back, the tail being extremely short, and the neck greatly
+lengthened out, and composed of from twenty to forty vertebræ.
+The bodies of the vertebræ, also, are not deeply biconcave, but
+are flat, or only slightly cupped. The head is of relatively small
+size, with smaller orbits than those of the <i>Ichthyosaur</i>,
+and with a snout less elongated. The jaws, however, were armed
+with numerous conical teeth, inserted in distinct sockets. As
+regards the habits of the Plesiosaur, Dr Conybeare arrives at
+the following conclusions: "That it was aquatic is evident from
+the form of its paddles; that it was marine is almost equally so
+from the remains with which it is universally associated; that
+it may have occasionally visited the shore, the resemblance of
+its extremities to those of the Turtles may lead us to conjecture:
+its movements, however, must have been very awkward on land;
+and its long neck must have impeded its progress through the
+water, presenting a strong contrast to the organisation which so
+admirably fits the <i>Ichthyosaurus</i> to cut through the waves."
+As its respiratory organs were such that it must of necessity
+have required to obtain air frequently, we may conclude "that
+it swam upon or near the surface, arching back its long neck
+like a swan, and occasionally darting it down at the fish which
+happened to float within its reach. It may perhaps have lurked
+in shoal water along the coast, concealed amongst the sea-weed;
+and raising its nostrils to a level with
+<a name="page_245"><span class="page">Page 245</span></a>
+the surface from a considerable depth, may have found a secure
+retreat from the assaults of powerful enemies; while the length
+and flexibility of its neck may have compensated for the want
+of strength in its jaws, and its incapacity for swift-motion
+through the water."
+</p>
+
+<p class="indent">
+About twenty species of <i>Plesiosaurus</i> are known, ranging
+from the Lias to the Chalk, and specimens have been found indicating
+a length of from eighteen to twenty feet. The nearly related
+"<i>Pliosaurs</i>," however, with their huge heads and short
+necks, must have occasionally reached a length of at least forty
+feet&mdash;the skull in some species being eight, and the paddles
+six or seven feet long, whilst the teeth are a foot in length.
+</p>
+
+<p class="indent">
+Another extraordinary group of Jurassic Reptiles is that of the
+"Winged Lizards" or <i>Pterosauria</i>. These are often spoken
+of collectively as "Pterodactyles," from <i>Pterodactylus</i>,
+the type-genus of the group. As now restricted, however, the
+genus <i>Pterodactylus</i> is more Cretaceous than Jurassic, and
+it is associated in the Oolitic rocks with the closely allied
+genera <i>Dimorphodon</i> and <i>Rhamphorhynchus</i>. In all
+three of these genera we have the same general structural
+organisation, involving a marvellous combination of characters,
+which we are in the habit of regarding as peculiar to Birds on
+the one hand, to Reptiles on another hand, and to the Flying
+Mammals or Bats in a third direction. The "Pterosaurs" are "Flying"
+Reptiles, in the true sense of the term, since they were indubitably
+possessed of the power of active locomotion in the air, after the
+manner of Birds. The so-called "Flying" Reptiles of the present
+day, such as the little <i>Draco volans</i> of the East Indies
+and Indian Archipelago, possess, on the other hand, no power
+of genuine flight, being merely able to sustain themselves in
+the air through the extensive leaps which they take from tree
+to tree, the wing-like expansions of the skin simply exercising
+the mechanical function of a parachute. The apparatus of flight
+in the "Pterosaurs" is of the most remarkable character, and most
+resembles the "wing" of a Bat, though very different in some
+important particulars. The "wing" of the Pterosaurs is like that
+of Bats, namely, in consisting of a thin leathery expansion of the
+skin which is attached to the sides of the body, and stretches
+between the fore and hind limbs, being mainly supported by an
+enormous elongation of certain of the digits of the hand. In
+the Bats, it is the four outer fingers which are thus lengthened
+out; but in the Pterosaurs, the wing-membrane is borne by a single
+immensely-extended finger (fig. 178). No trace of the actual
+wing-membrane itself has, of course,
+<a name="page_246"><span class="page">Page 246</span></a>
+been found fossilised; but
+we could determine that the "Pterodactyles" possessed the power
+of flight, quite apart from the extraordinary conformation of
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 431px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig178.jpg" width="431" height="376" alt="Fig. 178" />
+<br />
+Fig. 178.&mdash;<i>Pterodactylus crassirostis</i>. From the
+Lithographic Slates of Solenhofen (Middle Oolite). The figure is
+"restored," and it seems certain that the restoration is incorrect
+in the comparatively unimportant particular, that the hand should
+consist of no more than four fingers, three short and one long,
+instead of five, as represented.
+</span>
+</span>
+
+the hand. The proofs of this are to be found partly in the fact
+that the breast-bone was furnished with an elevated ridge or
+keel, serving for the attachment of the great muscles of flight,
+and still more in the fact that the bones were hollow and were
+filled with air&mdash;a peculiarity wholly confined amongst living
+animals to Birds only. The skull of the Pterosaurs is long, light,
+and singularly bird-like in appearance&mdash;a resemblance which is
+further increased by the comparative length of the neck and the size
+of the vertebræ of this region (fig. 178). The jaws, however,
+unlike those of any existing Bird, were, with one exception to be
+noticed hereafter, furnished with conical teeth sunk in distinct
+sockets; and there was always a longer or shorter tail composed
+of distinct vertebræ; whereas in all existing Birds the tail
+is abbreviated, and the terminal vertebræ are amalgamated to
+form a single bone, which generally supports the great feathers
+of the tail.
+</p>
+
+<p class="indent">
+Modern naturalists have been pretty generally agreed that the
+<i>Pterosaurs</i> should be regarded as a peculiar group of the
+Reptiles; though they have been and are still regarded by high
+authorities, like Professor Seeley, as being really referable
+<a name="page_247"><span class="page">Page 247</span></a>
+to the Birds, or as forming a class by
+themselves. The chief points which separate them from Birds, as
+a class, are the character of the apparatus of flight, the
+entirely different structure of the fore-limb, the absence of
+feathers, the composition of the tail out of distinct
+vertebræ, and the general presence of conical teeth sunk
+in distinct sockets in the jaws. The gap between the Pterosaurs
+and the Birds has, however, been greatly lessened of late by
+the discovery of fossil animals (<i>Ichthyornis</i> and
+<i>Hesperornis</i>) with the skeleton proper to Birds combined
+with the presence of teeth in the jaws, and by the still more
+recent discovery of other fossil animals (<i>Pteranodon</i>)
+with a Pterosaurian skeleton, but without teeth; whilst the
+undoubtedly feathered <i>Archœopteryx</i> possessed a long
+tail composed of separate vertebræ. Upon the whole, therefore,
+the relationships of the Pterosaurs cannot be regarded as absolutely
+settled. It seems certain, however, that they did not possess
+feathers&mdash;this implying that they were cold-blooded animals;
+and their affinities with Reptiles in this, as in other characters,
+are too strong to be overlooked.
+</p>
+
+<p class="indent">
+The <i>Pterosaurs</i> are wholly Mesozoic, ranging from the Lias
+to the Chalk inclusive; and the fine-grained Lithographic Slate
+of Solenhofen has proved to be singularly rich in their remains.
+The genus <i>Pterodactylus</i> itself has the jaws toothed to the
+extremities with equal-sized conical teeth, and its species range
+from the Middle Oolites to the Cretaceous series, in connection
+with which they will be again noticed, together with the toothless
+genus <i>Pteranodon</i>. The genus <i>Dimorphodon</i> is Liassic,
+and is characterised by having the front teeth long and pointed,
+whilst the hinder teeth are small and lancet-shaped. Lastly,
+the singular genus <i>Rhamphorhynchus</i>, also from the Lower
+Oolites, is distinguished by the fact that there are teeth present
+in the hinder portions of both jaws; but the front portions are
+toothless, and may have constituted a horny beak. Like most of
+the other Jurassic Pterosaurs, <i>Rhamphorhynchus</i> (fig. 179)
+does not seem to have been much bigger than a pigeon, in this
+respect falling far below the giant "Dragons" of the Cretaceous
+period. It differed from its relatives, not only in the armature of
+the mouth, but also in the fact that the tail was of considerable
+length. With regard to its habits and mode of life, Professor
+Phillips remarks that, "gifted with ample means of flight, able
+at least to perch on rocks and scuffle along the shore, perhaps
+competent to dive, though not so well as a Palmiped bird, many
+fishes must have yielded to the cruel beak and sharp teeth of
+Rhamphorhynchus. If we ask to which of the many families of Birds
+the analogy of
+<a name="page_248"><span class="page">Page 248</span></a>
+structure and probable way of life would lead us
+to assimilate Rhamphorhynchus, the answer must point to the
+swimming races with long wings, clawed feet, hooked beak, and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 428px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig179.jpg" width="428" height="176" alt="Fig. 179" />
+<br />
+Fig. 179&mdash;<i>Rhamphorhynchus Bucklandi</i>, restored. Bath
+Oolite, England. (After the late Professor Phillips.)
+</span>
+</span>
+
+habits or violence and voracity; and for preference, the shortness
+of the legs, and other circumstances, may be held to claim for
+the Stonesfield fossil a more than fanciful similitude to the
+groups of Cormorants, and other marine divers, which constitute
+an effective part of the picturesque army of robbers of the sea."
+</p>
+
+<p class="indent">
+Another extraordinary and interesting group of the Mesozoic Reptiles
+is constituted by the <i>Deinosauria</i>, comprising a series of
+mostly gigantic forms, which range from the Trias to the Chalk.
+All the "Deinosaurs" are possessed of the two pairs of limbs
+proper to Vertebrate animals, and these organs are in the main
+adapted for walking on the dry land. Thus, whilst the Mesozoic
+seas swarmed with the huge Ichthyosaurs and Plesiosaurs, and
+whilst the air was tenanted by the Dragon-like Pterosaurs, the
+land-surfaces of the Secondary period were peopled by numerous
+forms of Deinosaurs, some of them of even more gigantic dimensions
+than their marine brethren. The limbs of the <i>Deinosaurs</i>
+are, as just said, adapted for progression on the land; but in
+some cases, at any rate, the hind-limbs were much longer and
+stronger than the fore-limbs; and there seems to be no reason to
+doubt that many of these forms possessed the power of walking,
+temporarily or permanently, on their hind-legs, thus presenting
+a singular resemblance to Birds. Some very curious and striking
+points connected with the structure of the skeleton have also
+been shown to connect these strange Reptiles with the true Birds;
+and such high authorities as Professors Huxley and Cope are of
+opinion that the Deinosaurs are distinctly related to this class,
+being in some respects intermediate between the proper Reptiles
+and the great wingless Birds, like the Ostrich and Cassowary.
+On the other hand, Professor Owen has shown that the Deinosaurs
+<a name="page_249"><span class="page">Page 249</span></a>
+possess some weighty points of relationship
+with the so-called "Pachydermatous" Quadrupeds, such as the
+Rhinoceros and Hippopotamus. The most important Jurassic genera
+of <i>Deinosauria</i> are <i>Megalosaurus</i> and
+<i>Cetiosaurus</i>, both of which extend their range into the
+Cretaceous period, in which flourished, as we shall see, some
+other well-known members of this order.
+</p>
+
+<p class="indent">
+<i>Megalosaurus</i> attained gigantic dimensions, its thigh and
+shank bones measuring each about three feet in length, and its
+total length, including the tail, being estimated at from forty
+to fifty feet. As the head of the thigh-bone is set on nearly at
+right angles with the shaft, whilst all the long bones of the
+skeleton are hollowed out internally for the reception of the
+marrow, there can be no doubt as to the terrestrial habits of
+the animal. The skull (fig. 180) was of large size, four or five
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 492px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig180.jpg" width="492" height="299" alt="Fig. 180" />
+<br />
+Fig. 180.&mdash;Skull of <i>Megalosaurus</i>, on a scale
+one-tenth of nature. Restored. (After Professor Phillips.)
+</span>
+</span>
+
+feet in length, and the jaws were armed with a series of powerful
+pointed teeth. The teeth are conical in shape, but are strongly
+compressed towards their summits, their lateral edges being finely
+serrated. In their form and their saw-like edges, they resemble
+the teeth of the "Sabre-toothed Tiger" (<i>Machairodus</i>), and
+they render it certain that the Megalosaur was in the highest
+degree destructive and carnivorous in its habits. So far as is
+known, the skin was not furnished with any armour of scales or bony
+plates; and the fore-limbs are so disproportionately small as
+compared with the hind-limbs, that this huge Reptile&mdash;like
+the equally huge Iguanodon&mdash;may be
+<a name="page_250"><span class="page">Page 250</span></a>
+conjectured to have commonly supported itself on its hind-legs
+only.
+</p>
+
+<p class="indent">
+The <i>Cetiosaur</i> attained dimensions even greater than those
+of the Megalosaur, one of the largest thigh-bones measuring over
+five feet in length and a foot in diameter in the middle, and the
+total length of the animal being probably not less than fifty
+feet. It was originally regarded as a gigantic Crocodile, but
+it has been shown to be a true Deinosaur. Having obtained a
+magnificent series of remains of this reptile, Professor Phillips
+has been able to determine many very interesting points as to
+the anatomy and habits of this colossal animal, the total length
+of which he estimates as being probably not less than sixty or
+seventy feet. As to its mode of life, this accomplished writer
+remarks:&mdash;
+</p>
+
+<p class="indent">
+"Probably when 'standing at ease' not less than ten feet in height,
+and of a bulk in proportion, this creature was unmatched in magnitude
+and physical strength by any of the largest inhabitants of the
+Mesozoic land or sea. Did it live in the sea, in fresh waters,
+or on the land? This question cannot be answered, as in the case
+of Ichthyosaurus, by appeal to the accompanying organic remains;
+for some of the bones lie in marine deposits, others in situations
+marked by estuarine conditions, and, out of the Oxfordshire district,
+in Sussex, in fluviatile accumulations. Was it fitted to live
+exclusively in water? Such an idea was at one time entertained,
+in consequence of the biconcave character of the caudal vertebræ,
+and it is often suggested by the mere magnitude of the creature,
+which would seem to have an easier life while floating in water,
+than when painfully lifting its huge bulk, and moving with slow
+steps along the ground. But neither of these arguments is valid. The
+ancient earth was trodden by larger quadrupeds than our elephant;
+and the biconcave character of vertebræ, which is not uniform
+along the column in Cetiosaurus, is perhaps as much a character
+of a geological period as of a mechanical function of life. Good
+evidence of continual life in water is yielded in the case of
+Ichthyosaurus and other Enaliosaurs, by the articulating surfaces
+of their limb-bones, for these, all of them, to the last phalanx,
+have that slight and indefinite adjustment of the bones, with much
+intervening cartilage, which fits the leg to be both a flexible
+and forcible instrument of natation, much superior to the ordinary
+oar-blade of the boatman. On the contrary, in Cetiosaur, as well as
+in Megalosaur and Iguanodon, all the articulations are definite,
+and made so as to correspond to determinate movements in particular
+directions, and these are such as to be suited
+<a name="page_251"><span class="page">Page 251</span></a>
+for walking. In particular, the femur, by its head projecting
+freely from the acetabulum, seems to claim a movement of free
+stepping more parallel to the line of the body, and more
+approaching to the vertical than the sprawling gait of the
+crocodile. The large claws concur in this indication of
+terrestrial habits. But, on the other hand, these characters are
+not contrary to the belief that the animal may have been
+amphibious; and the great vertical height of the anterior part
+of the tail seems to support this explanation, but it does not
+go further.... We have therefore a marsh-loving or river-side
+animal, dwelling amidst filicine, cycadaceous, and coniferous
+shrubs and trees full of insects and small mammalia. What was
+its usual diet? If <i>ex ungue leonem</i>, surely <i>ex dente
+cibum</i>. We have indeed but one tooth, and that small and
+incomplete. It resembles more the tooth of Iguanodon than that
+of any other reptile; for this reason it seems probable that
+the animal was nourished by similar vegetable food which
+abounded in the vicinity, and was not obliged to contend with
+Megalosaurus for a scanty supply of more stimulating diet."
+</p>
+
+<p class="indent">
+All the groups of Jurassic Reptiles which we have hitherto been
+considering are wholly unrepresented at the present day, and
+do not even pass upwards into the Tertiary period. It may be
+mentioned, however, that the Oolitic deposits have also yielded
+the remains of Reptiles belonging to three of the existing orders
+of the class-namely, the Lizards (<i>Lacertilia</i>), the Turtles
+(<i>Chelonia</i>), and the Crocodiles (<i>Crocodilia</i>). The
+Lizards occur both in the marine strata of the Middle Oolites and
+also in the fresh-water beds of the Purbeck series; and they are of
+such a nature that their affinities with the typical Lacertilians
+of the present day cannot be disputed. The Chelonians, up to
+this point only known by the doubtful evidence of footprints
+in the Permian and Triassic sandstones, are here represented by
+unquestionable remains, indicating the existence of marine Turtles
+(the <i>Chelone planiceps</i> of the Portland Stone). No remains
+of Serpents (<i>Ophidians</i>) have as yet been detected in the
+Jurassic; but strata of this age have yielded the remains of
+numerous <i>Crocodilians</i>, which probably inhabited the sea.
+The most important member of this group is <i>Teleosaurus</i>,
+which attained a length of over thirty feet, and is in some
+respects allied to the living Gavials of India.
+</p>
+
+<p class="indent">
+The great class of the Birds, as we have seen, is represented
+in rocks earlier than the Oolites simply by the not absolutely
+certain evidence of the three-toed footprints of the Connecticut
+Trias. In the Lithographic Slate of Solenhofen (Middle
+<a name="page_252"><span class="page">Page 252</span></a>
+Oolite), there has been discovered,
+however, the at present unique skeleton of a Bird well known
+under the name of the <i>Archœopteryx macrura</i> (figs.
+181, 182). The only known specimen&mdash;now in the British
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 520px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig181.jpg" width="520" height="311" alt="Fig. 181" />
+<br />
+Fig. 181.&mdash;<i>Archœopteryx macrura</i>, showing
+tail and tail-feathers, with detached bones. Reduced. From the
+Lithographic Slate of Solenhofen.
+</span>
+</span>
+
+Museum&mdash;unfortunately does not exhibit the skull; but the
+fine-grained matrix has preserved a number of the other bones
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 551px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig182.jpg" width="551" height="299" alt="Fig. 182" />
+<br />
+Fig. 182.&mdash;Restoration of <i>Archœopteryx macrura</i>.
+(After Owen.)
+</span>
+</span>
+
+of the skeleton, along with the impressions of the tail and wing
+feathers. From these remains we know that <i>Archœopteryx</i>
+differed in some remarkable
+<a name="page_253"><span class="page">Page 253</span></a>
+peculiarities of its structure from all existing members of the
+class of Birds. This extraordinary Bird (fig. 182) appears to
+have been about as big as a Rook&mdash;the tail being long and
+extremely slender, and composed of separate vertebræ, each
+of which supports a single pair of quill-feathers. In the flying
+Birds of the present day, as before mentioned, the terminal
+vertebræ of the tail are amalgamated to form a single bone
+("ploughshare-bone"), which supports a cluster of tail-feathers;
+and the tail itself is short. In the embryos of existing Birds
+the tail is long, and is made up of separate vertebræ, and the
+same character is observed in many existing Reptiles. The tail
+of <i>Archœopteryx</i>, therefore, is to be regarded as the
+permanent retention of an embryonic type of structure, or as an
+approximation to the characters of the Reptiles. Another remarkable
+point in connection with <i>Archœopteryx</i>, in which it
+differs from all known Birds, is, that the wing was furnished with two
+free claws. From the presence of feathers, <i>Archœopteryx</i>
+may be inferred to have been hot-blooded; and this character,
+taken along with the structure of the skeleton of the wing, may
+be held as sufficient to justify its being considered as belonging
+to the class of Birds. In the structure of the tail, however,
+it is singularly Reptilian; and there is reason to believe that
+its jaws were furnished with teeth sunk in distinct sockets,
+as is the case in no existing Bird. This conclusion, at any rate,
+is rendered highly probable by the recent discovery of "Toothed
+Birds" (<i>Odonturnithes</i>) in the Cretaceous rocks of North
+America.
+</p>
+
+<p class="indent">
+The <i>Mammals</i> of the Jurassic period are known to us by
+a number of small forms which occur in the "Stonesfield Slate"
+(Great Oolite) and in the Purbeck beds (Upper Oolite). The remains
+of these are almost exclusively separated halves of the lower
+jaw, and they indicate the existence during the Oolitic period in
+Europe of a number of small "Pouched animals" (<i>Marsupials</i>).
+In the horizon of the Stonesfield Slate four genera of these
+little Quadrupeds have been described&mdash;viz., <i>Amphilestes,
+Amphitherium, Phascolotherium</i>, and <i>Stereognathus</i>. In
+<i>Amphitherium</i> (fig. 183), the molar teeth are furnished with
+small pointed eminences or "cusps;" and the animal was doubtless
+insectivorous. By Professor Owen, the highest living authority
+on the subject, <i>Amphitherium</i> is believed to be a small
+Marsupial, most nearly allied to the living Banded Ant-eater
+(<i>Myrmecobius</i>) of Australia (fig. 158). <i>Amphilestes</i>
+and <i>Phascolotherium</i> (fig. 184) are also believed by the
+same distinguished anatomist and palæontologist to have been
+insect-eating Marsupials, and
+<a name="page_254"><span class="page">Page 254</span></a>
+the latter is supposed to
+find its nearest living ally in the Opossums (<i>Didelphys</i>)
+of America. Lastly, the <i>Stereognathus</i> of the Stonesfield
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 293px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig183.jpg" width="293" height="110" alt="Fig. 183" />
+<br />
+Fig. 183.&mdash;Lower jaw of <i>Amphitherium</i>
+(<i>Thylacotherium</i>) <i>Prevostii</i>. Stonesfield Slate
+(Great Oolite.)
+</span>
+</span>
+
+Slate is in a dubious position. It may have been a Marsupial;
+but, upon the whole, Professor Owen is inclined to believe that
+it must have been a hoofed and herbivorous Quadruped belonging
+to the series of the higher Mammals (<i>Placentalia</i>). In the
+Middle Purbeck beds, near to the close of the Oolitic period, we
+have also evidence of the existence of a number of small Mammals,
+all of which are probably Marsupials. Fourteen species are known,
+all of small size, the largest being no bigger than a Polecat
+or Hedgehog. The genera to which these little quadrupeds have
+been referred are <i>Plagiaulax, Spalacotherium, Triconodon</i>,
+and <i>Galestes</i>. The first of these (fig. 184, 4) is believed
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 449px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig184.jpg" width="449" height="199" alt="Fig. 184" />
+<br />
+Fig. 184. Oolitic Mammals.&mdash;1, Lower jaw and teeth of
+<i>Phascolotherium</i>, Stonesfield Slate; 2, Lower jaw and
+teeth of <i>Amphitherium</i>, Stonesfield Slate; 3, Lower jaw
+and teeth of <i>Triconodon</i>, Purbeck beds; 4, Lower jaw and
+teeth of <i>Plagiaulax</i>, Purbeck beds. All the figures are
+of the natural size.
+</span>
+</span>
+
+by Professor Owen to have been carnivorous in its habits; but
+other authorities maintain that it was most nearly allied to
+the living Kangaroo-rats (<i>Hypsiprymnus</i>) of Australia,
+and that it was essentially herbivorous. The remaining three
+genera appear to have been certainly insectivorous, and find
+their nearest living representatives in the Australian Phalangers
+and the American Opossums.
+</p>
+
+<p class="indent">
+Finally, it is interesting to notice in how many respects the
+<a name="page_255"><span class="page">Page 255</span></a>
+Jurassic fauna of Western Europe approached
+to that now inhabiting Australia. At the present day, Australia
+is almost wholly tenanted by Marsupials; upon its land-surface
+flourish <i>Araucariœ</i> and Cycadaceous plants, and in
+its seas swims the Port-Jackson Shark (<i>Cestracion
+Philippi</i>); whilst the Molluscan genus <i>Trigonia</i> is
+nowadays exclusively confined to the Australian coasts. In
+England, at the time of the deposition of the Jurassic rocks,
+we must have had a fauna and flora very closely resembling what
+we now see in Australia. The small Marsupials, <i>Amphitherium,
+Phascolotherium</i>, and others, prove that the Mammals were
+the same in order; cones of Araucarian pines, with tree-ferns
+and fronds of Cycads, occur throughout the Oolitic series;
+spine-bearing fishes, like the Port-Jackson Shark, are abundantly
+represented by genera such as <i>Acrodus</i> and <i>Strophodus</i>;
+and lastly, the genus <i>Trigonia</i>, now exclusively Australian,
+is represented in the Oolites by species which differ little
+from those now existing. Moreover, the discovery during recent
+years of the singular Mud-fish, the <i>Ceratodus Fosteri</i> in
+the rivers of Queensland, has added another and a very striking
+point of resemblance to those already mentioned; since this genus
+of Fishes, though preeminently Triassic, nevertheless extended
+its range into the Jurassic. Upon the whole, therefore, there
+is reason to conclude that Australia has undergone since the
+close of the Jurassic period fewer changes and vicissitudes than
+any other known region of the globe; and that this wonderful
+continent has therefore succeeded in preserving a greater number
+of the characteristic life-features of the Oolites than any other
+country with which we are acquainted.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following list comprises some of the more important sources
+of information as to the rocks and fossils of the Jurassic
+series:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Geology of Oxford and the Thames Valley.' Phillips.</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Geology of Yorkshire,' vol. ii. Phillips.</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Memoirs of the Geological Survey of Great Britain.'</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>'Geology of Cheltenham.' Murchison, 2d ed. Buckman.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>'Introduction to the Monograph of the Oolitic Asteriadæ'
+(Palæontographical Society). Wright.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>"Zone of Avicula contorta and the Lower Lias of the South of
+  England"&mdash;'Quart. Journ. Geol. Soc.,' vol. xvi., 1860.
+  Wright.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>"Oolites of Northamptonshire"&mdash;'Quart. Journ. Geol. Soc.,'
+  vols. Xxvi. and xxix. Sharp.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>'Manual of Geology.' Dana.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>'Der Jura.' Quenstedt.</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Das Flötzgebirge W&uuml;rttembergs.'
+  Quenstedt.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'Jura Formation.' Oppel.</td></tr>
+<tr><td class="right" valign="top">
+<a name="page_256"><span class="page">Page 256</span></a>
+  (12)</td>
+ <td>'Paléontologie du Département de la Moselle.'
+  Terquem.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>'Cours élémentaire de Paléontologie.'
+  D'Orbigny.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>'Paléontologie Fran&ccedil;aise.' D'Orbigny.</td></tr>
+<tr><td class="right" valign="top">(15)</td>
+ <td>'Fossil Echinodermata of the Oolitic Formation'
+(Palæontographical Society). Wright.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Brachiopoda of the Oolitic Formation'
+  (Palæontographical Society). Davidson.</td></tr>
+<tr><td class="right" valign="top">(17)</td>
+ <td>'Mollusca of the Great Oolite' (Palæontographical
+  Society). Morris and Lycett.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>'Monograph of the Fossil Trigoniæ'
+  (Palæontographical Society). Lycett.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>'Corals of the Oolitic Formation' (Palæontographical
+  Society). Edwards and Haime.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>'Supplement to the Corals of the Oolitic Formation'
+(Palæontographical Society). Martin Duncan.</td></tr>
+<tr><td class="right" valign="top">(21)</td>
+ <td>'Monograph of the Belemnitidæ'
+  (Palæontographical Society). Phillips.</td></tr>
+<tr><td class="right" valign="top">(22)</td>
+ <td>'Structure of the Belemnitidæ' (Mem. Geol. Survey).
+  Huxley.</td></tr>
+<tr><td class="right" valign="top">(23)</td>
+ <td>'Sur les Belemnites.' Blainville.</td></tr>
+<tr><td class="right" valign="top">(24)</td>
+ <td>'Cephalopoden.' Quenstedt.</td></tr>
+<tr><td class="right" valign="top">(25)</td>
+ <td>'Mineral Conchology.' Sowerby.</td></tr>
+<tr><td class="right" valign="top">(26)</td>
+ <td>'Jurassic Cephalopoda' (Palæontologica Indica).
+  Waagen.</td></tr>
+<tr><td class="right" valign="top">(27)</td>
+ <td>'Manual of the Mollusca.' Woodward.</td></tr>
+<tr><td class="right" valign="top">(28)</td>
+ <td>'Petrefaktenkunde.' Schlotheim.</td></tr>
+<tr><td class="right" valign="top">(29)</td>
+ <td>'Bridgewater Treatise.' Buckland.</td></tr>
+<tr><td class="right" valign="top">(30)</td>
+ <td>'Versteinerungen des Oolithengebirges.' Roemer.</td></tr>
+<tr><td class="right" valign="top">(31)</td>
+ <td>'Catalogue of British Fossils.' Morris.</td></tr>
+<tr><td class="right" valign="top">(32)</td>
+ <td>'Catalogue of Fossils in the Museum of Practical Geology.'
+  Etheridge.</td></tr>
+<tr><td class="right" valign="top">(33)</td>
+ <td>'Beitr&auml;ge zur Petrefaktenkunde.'
+  M&uuml;nster.</td></tr>
+<tr><td class="right" valign="top">(34)</td>
+ <td>'Petrefacta Germaniæ.' Goldfuss.</td></tr>
+<tr><td class="right" valign="top">(35)</td>
+ <td>'Lethæa Rossica.' Eichwald.</td></tr>
+<tr><td class="right" valign="top">(36)</td>
+ <td>'Fossil Fishes' (Decades of the Geol. Survey). Sir Philip
+  Egerton.</td></tr>
+<tr><td class="right" valign="top">(37)</td>
+ <td>'Manual of Palæontology.' Owen.</td></tr>
+<tr><td class="right" valign="top">(38)</td>
+ <td>'British Fossil Mammals and Birds.' Owen.</td></tr>
+<tr><td class="right" valign="top">(39)</td>
+ <td>'Monographs of the Fossil Reptiles of the Oolitic
+  Formation' (Palæontographical Society). Owen.</td></tr>
+<tr><td class="right" valign="top">(40)</td>
+ <td>'Fossil Mammals of the Mesozoic Formations'
+  (Palæontographical Society). Owen.</td></tr>
+<tr><td class="right" valign="top">(41)</td>
+ <td>'Catalogue of Ornithosauria.' Seeley.</td></tr>
+<tr><td class="right" valign="top">(42)</td>
+ <td>"Classification of the Deinosauria"&mdash;'Quart. Journ.
+  Geol. Soc.,' vol. xxvi., 1870. Huxley.</td></tr>
+</table>
+
+<h3>CHAPTER XVII.</h3>
+
+<p class="subtitle">
+THE CRETACEOUS PERIOD.
+</p>
+
+<p class="indent">
+The next series of rocks in ascending order is the great and
+important series of the Cretaceous Rocks, so called from the
+general occurrence in the system of chalk (Lat. <i>creta</i>,
+<a name="page_257"><span class="page">Page 257</span></a>
+chalk). As developed in Britain and Europe generally, the
+following leading subdivisions may be recognised in the
+Cretaceous series:&mdash;
+</p>
+
+<div class="center">
+<table border="1" cellspacing="0" cellpadding="3">
+ <tr><td class="left">
+ 1.&nbsp;Wealden,<br/>
+ 2.&nbsp;Lower&nbsp;Greensand&nbsp;or&nbsp;Neocomian,
+ </td><td class="center">Lower&nbsp;Cretaceous.</td></tr>
+
+ <tr><td class="left">
+ 3.&nbsp;Gault,<br/>
+ 4.&nbsp;Upper&nbsp;Greensand,<br/>
+ 5.&nbsp;Chalk,<br/>
+ 6.&nbsp;Maestricht&nbsp;beds,<br/>
+ </td><td class="center">Upper&nbsp;Cretaceous.</td></tr>
+</table>
+</div>
+
+<p class="indent">
+I. <i>Wealden</i>.&mdash;The <i>Wealden</i> formation, though of
+considerable importance, is a local group, and is confined to
+the southeast of England, France, and some other parts of Europe.
+Its name is derived from the <i>Weald</i>, a district comprising
+parts of Surrey, Sussex, and Kent, where it is largely developed.
+Its lower portion, for a thickness of from 500 to 1000 feet,
+is arenaceous, and is known as the Hastings Sands. Its Upper
+portion, for a thickness of 150 to nearly 300 feet, is chiefly
+argillaceous, consisting of clays with sandy layers, and occasionally
+courses of limestone. The geological importance of the Wealden
+formation is very great, as it is undoubtedly the delta of an
+ancient river, being composed almost wholly of fresh-water beds,
+with a few brackish-water and even marine strata, intercalated
+in the lower portion. Its geographical extent, though uncertain,
+owing to the enormous denudation to which it has been subjected,
+is nevertheless great, since it extends from Dorsetshire to France,
+and occurs also in North Germany. Still, even if it were continuous
+between all these points, it would not be larger than the delta
+of such a modern river as the Ganges. The river which produced
+the Wealden series must have flowed from an ancient continent
+occupying what is now the Atlantic Ocean; and the time occupied
+in the formation of the Wealden must have been very great, though
+we have, of course, no data by which we can accurately calculate
+its duration.
+</p>
+
+<p class="indent">
+The fossils of the Wealden series are, naturally, mostly the
+remains of such animals as we know at the present day as inhabiting
+rivers. We have, namely, fresh-water Mussels (<i>Unio</i>),
+River-snails (<i>Paludina</i>), and other fresh-water shells,
+with numerous little bivalved Crustaceans, and some fishes.
+</p>
+
+<p class="indent">
+II. <i>Lower Greensand</i> (<i>Néocomien</i> of
+D'Orbigny).&mdash;The Wealden beds pass upward, often by insensible
+gradations, into the Lower Greensand. The name Lower Greensand is
+not an appropriate one, for green sands only occur sparingly and
+occasionally, and are found in other formations. For this
+<a name="page_258"><span class="page">Page 258</span></a>
+reason it has been proposed to substitute for Lower Greensand the
+name <i>Neocomian</i>, derived from the town of
+Neufchâtel&mdash;anciently called <i>Neocomum</i>&mdash;in
+Switzerland. If this name were adopted, as it ought to be, the
+Wealden beds would be called the Lower Neocomian.
+</p>
+
+<p class="indent">
+The Lower Greensand or Neocomian of Britain has a thickness of
+about 850 feet, and consists of alternations of sands, sandstones,
+and clays, with occasional calcareous bands. The general colour
+of the series is dark brown, sometimes red; and the sands are
+occasionally green, from the presence of silicate of iron.
+</p>
+
+<p class="indent">
+The fossils of the Lower Greensand are purely marine, and among
+the most characteristic are the shells of <i>Cephalopods</i>.
+</p>
+
+<p class="indent">
+The most remarkable point, however, about the fossils of the
+Lower Cretaceous series, is their marked divergence from the
+fossils of the Upper Cretaceous rocks. Of 280 species of fossils
+in the Lower Cretaceous series, only 51, or about 18 per cent, pass
+on into the Upper Cretaceous. This break in the life of the two
+periods is accompanied by a decided physical break as well; for the
+Gault is often, if not always, unconformably superimposed on the
+Lower Greensand. At the same time, the Lower and Upper Cretaceous
+groups form a closely-connected and inseparable series, as shown
+by a comparison of their fossils with those of the underlying
+Jurassic rocks and the overlying Tertiary beds. Thus, in Britain
+no marine fossil is known to be common to the marine beds of
+the Upper Oolites and the Lower Greensand; and of more than 500
+species of fossils in the Upper Cretaceous rocks, almost everyone
+died out before the formation of the lowest Tertiary strata, the
+only survivors being one Brachiopod and a few <i>Foraminifera</i>.
+</p>
+
+<p class="indent">
+III. <i>Gault</i> (<i>Aptien</i> of D'Orbigny).&mdash;The lowest
+member of the Upper Cretaceous series is a stiff, dark-grey, blue,
+or brown clay, often worked for brick-making, and known as the
+<i>Gault</i>, from a provincial English term. It occurs chiefly
+in the south-east of England, but can be traced through France
+to the flanks of the Alps and Bavaria. It never exceeds 100 feet
+in thickness; but it contains many fossils, usually in a state
+of beautiful preservation.
+</p>
+
+<p class="indent">
+IV. <i>Upper Greensand</i> (<i>Albien</i> of D'Orbigny;
+<i>Unterquader</i> and <i>Lower Pl&auml;nerkalk</i> of
+Germany).&mdash;The Gault is succeeded upward by the <i>Upper
+Greensand</i>, which varies in thickness from 3 up to 100 feet,
+and which derives its name from the occasional occurrence in it
+of green sands. These, however, are local and sometimes wanting,
+and the name "Upper
+<a name="page_259"><span class="page">Page 259</span></a>
+Greensand" is to be
+regarded as a <i>name</i> and not a description. The group
+consists, in Britain, of sands and clays, sometimes with bands
+of calcareous grit or siliceous limestone, and occasionally
+containing concretions of phosphate of lime, which are largely
+worked for agricultural purposes.
+</p>
+
+<p class="indent">
+V. <i>White Chalk</i>.&mdash;The top of the Upper Greensand becomes
+argillaceous, and passes up gradually into the base of the great
+formation known as the true <i>Chalk</i>, divided into the three
+subdivisions of the chalk-marl, white chalk without flints, and
+white chalk with flints. The first of these is simply argillaceous
+chalk, and passes up into a great mass of obscurely-stratified white
+chalk in which there are no flints (<i>Turonien</i> of D'Orbigny;
+<i>Mittelquader</i> of Germany). This, in turn, passes up into a
+great mass of white chalk, in which the stratification is marked
+by nodules of black flint arranged in layers (<i>Sénonien</i>
+of D'Orbigny; <i>Oberquader</i> of Germany). The thickness of
+these three subdivisions taken together is sometimes over 1000
+feet, and their geographical extent is very great. White Chalk,
+with its characteristic appearance, may be traced from the north
+of Ireland to the Crimea, a distance of about 1140 geographical
+miles; and, in an opposite direction, from the south of Sweden
+to Bordeaux, a distance of about 840 geographical miles.
+</p>
+
+<p class="indent">
+VI. In Britain there occur no beds containing Chalk fossils, or
+in any way referable to the Cretaceous period, above the true
+White Chalk with flints. On the banks of the Maes, however, near
+Maestricht in Holland, there occurs a series of yellowish limestones,
+of about 100 feet in thickness, and undoubtedly superior to the
+White Chalk. These <i>Maestricht beds</i> (<i>Danien</i> of
+D'Orbigny) contain a remarkable series of fossils, the characters
+of which are partly Cretaceous and partly Tertiary. Thus, with
+the characteristic Chalk fossils, <i>Belemnites, Baculites</i>,
+Sea-Urchins, &amp;c., are numerous Univalve Molluscs, such as
+Cowries and Volutes, which are otherwise exclusively Tertiary or
+Recent.
+</p>
+
+<p class="indent">
+Holding a similar position to the Maestricht beds, and showing
+a similar intermixture of Cretaceous forms with later types, are
+certain beds which occur in the island of Seeland, in Denmark,
+and which are known as the <i>Faxöe Limestone</i>.
+</p>
+
+<p class="indent">
+Of a somewhat later date than the Maestricht beds is the <i>Pisolitic
+Limestone</i> of France, which rests unconformably on the White
+Chalk, and contains a large number of Tertiary fossils along
+with some characteristic Cretaceous types.
+</p>
+
+<p class="indent">
+The subjoined sketch-section exhibits the general succession of
+the Cretaceous deposits in Britain:&mdash;
+</p>
+
+<p class="indent">
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<a name="page_260"><span class="page">Page 260</span></a>
+GENERALIZED SECTION OF THE CRETACEOUS SERIES OF BRITAIN.
+<br />
+Fig. 185.
+<br />
+<img src="images/fig185.jpg" width="538" height="651" alt="Fig. 185" />
+</span>
+</span>
+
+In North America, strata of Lower Cretaceous age are well represented
+in Missouri, Wyoming, Utah, and in some other areas; but the greater
+portion of the American deposits of this period are referable
+to the Upper Cretaceous. The rocks of this series are mostly
+sands, clays, and limestones&mdash;<i>Chalk</i> itself being unknown
+except in Western Arkansas. Amongst the sandy accumulations, one
+of the most important is the
+<a name="page_261"><span class="page">Page 261</span></a>
+so-called "marl"
+of New Jersey, which is truly a "Greensand," and contains a large
+proportion of glauconite (silicate of iron and potash). It also
+contains a little phosphate of lime, and is largely worked for
+agricultural purposes. The greatest thickness attained by the
+Cretaceous rocks of North America is about 9000 feet, as in Wyoming,
+Utah, and Colorado. According to Dana, the Cretaceous rocks of the
+Rocky Mountain territories pass upwards "without interruption into
+a coal-bearing formation, several thousand feet thick, on which the
+following Tertiary strata lie unconformably." The lower portion of
+this "Lignitic formation" appears to be Cretaceous, and contains
+one or more beds of Coal; but the upper part of it perhaps belongs
+to the Lower Tertiary. In America, therefore, the lowest Tertiary
+strata appear to rest conformably upon the highest Cretaceous;
+whereas in Europe, the succession at this point is invariably an
+unconformable one. Owing, however, to the fact that the American
+"Lignitic formation" is a shallow-water formation, it can hardly
+be expected to yield much material whereby to bridge over the
+great palæontological gap between the White Chalk and Eocene
+in the Old World.
+</p>
+
+<p class="indent">
+Owing to the fact that so large a portion of the Cretaceous formation
+has been deposited in the sea, much of it in deep water, the
+<i>plants</i> of the period have for the most part been found
+special members of the series, such as the Wealden beds, the
+Aix-la-Chapelle sands, and the Lignitic beds of North America. Even
+the purely marine strata, however, have yielded plant-remains, and
+some of these are peculiar and proper to the deep-sea deposits of
+the series. Thus the little calcareous discs termed "coccoliths,"
+which are known to be of the nature of calcareous sea-weeds
+(<i>Algœ</i>) have been detected in the White Chalk; and the
+flints of the same formation commonly contain the spore-cases of
+the microscopic <i>Desmids</i> (the so-called Xanthidia), along
+with the siliceous cases of the equally diminutive <i>Diatoms</i>.
+</p>
+
+<p class="indent">
+The plant-remains of the Lower Cretaceous greatly resemble those
+of the Jurassic period, consisting mainly of Ferns, Cycads, and
+Conifers. The Upper Cretaceous rocks, however, both in Europe and
+in North America, have yielded an abundant flora which resembles
+the existing vegetation of the globe in consisting mainly of
+Angiospermous Exogens and of Monocotyledons.[23] In Europe the
+plant-remains in question have
+<a name="page_262"><span class="page">Page 262</span></a>
+been found chiefly in certain sands in the neighbourhood of
+Aix-la-Chapelle, and they consist of numerous Ferns, Conifers
+(such as <i>Cycadopteris</i>), Screw Pines (<i>Pandanus</i>), Oaks
+(<i>Quercus</i>), Walnut (<i>Juglans</i>), Fig (<i>Ficus</i>), and
+many <i>Proteaceœ</i>, some of which are referred to existing
+genera (<i>Dryandra, Banksia, Grevillea</i>, &amp;c.)
+</p>
+
+<p class="footnote">
+[Footnote 23: The "Flowering plants" are divided into the two
+great groups of the Endogens and Exogens. The <i>Endogens</i>
+(such as Grasses, Palms, Lilies, &amp;c.) have no true bark, nor
+rings of growth, and the stem is said to be "endogenous;" the young
+plant also possesses but a single seed-leaf or "cotyledon." Hence
+these plants are often simply called "<i>Monocotyledons</i>." The
+<i>Exogens</i>, on the other hand, have a true bark; and the stem
+increases by annual additions to the outside, so that rings of growth
+are produced. The young plant has two seed-leaves or "cotyledons,"
+and these plants are therefore called "<i>Dicotyledons</i>."
+Amongst the Exogens, the Pines (<i>Conifers</i>) and the Cycads
+have seeds which are unprotected by a seed-vessel, and they are
+therefore called "<i>Gymnosperms</i>." All the other Exogens,
+including the ordinary trees, shrubs, and flowering plants, have
+the seeds enclosed in a seed-vessel, and are therefore called
+"<i>Angiosperms</i>." The derivation of these terms will be found
+in the Glossary at the end of the volume.]
+</p>
+
+<p class="indent">
+In North America, the Cretaceous strata of New Jersey, Alabama,
+Nebraska, Kansas, &amp;c., have yielded the remains of numerous
+plants, many of which belong to existing genera. Amongst these
+may be mentioned Tulip-trees (<i>Liriodendron</i>), Sassafras (fig.
+186), Oaks (<i>Quercus</i>), Beeches (<i>Fagus</i>), Plane-trees
+(<i>Platanus</i>), Alders (<i>Alnus</i>), Dog-wood (<i>Cornus</i>),
+Willows (<i>Salix</i>), Poplars (<i>Populus</i>), Cypresses
+(<i>Cupressus</i>), Bald Cypresses (<i>Taxodium</i>), Magnolias,
+&amp;c. Besides these, however, there occur other forms which have
+now entirely disappeared from North America&mdash;as, for example,
+species of <i>Cinnamomum</i> and <i>Araucaria</i>.
+</p>
+
+<p class="indent">
+It follows from the above, that the Lower and Upper Cretaceous
+rocks are, from a botanical point of view, sharply separated
+from one another. The Palæozoic period, as we have seen, is
+characterised by the prevalance of "Flowerless" plants
+(<i>Cryptogams</i>), its higher vegetation consisting almost
+exclusively of Conifers. The Mesozoic period, as a whole, is
+characterised by the prevalence of the Cryptogamic group of the
+Ferns, and the Gymnospermic groups of the Conifers and the Cycads.
+Up to the close of the Lower Cretaceous, no Angiospermous Exogens
+are certainly known to have existed, and Monocotyledonous plants
+or Endogens are very poorly represented. With the Upper Cretaceous,
+however, a new era of plant-life, of which our present is but
+the culmination, commenced, with a great and apparently sudden
+development of new forms. In place of the Ferns, Cycads, and
+Conifers of the earlier Mesozoic deposits, we have now an
+astonishingly large number of true Angiospermous Exogens, many
+of them belonging to existing types; and along with these are
+various Monocotyledonous plants, including the first examples of
+the great and important
+<a name="page_263"><span class="page">Page 263</span></a>
+group of the Palms. It is thus a matter
+of interest to reflect that plants closely related to those now
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 510px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig186.jpg" width="510" height="495" alt="Fig. 186" />
+<br />
+Fig. 186.&mdash;Cretaceous Angiosperms. <i>a. Sassafras Cretaceum;
+b, Liriodendron Meekii; c, Leguminosites Marcouanus; d, Salix
+Meekii</i>. (After Dana.)
+</span>
+</span>
+
+inhabiting the earth, were in existence at a time when the ocean
+was tenanted by Ammonites and Belemnites, and when land and sea
+and air were peopled by the extraordinary extinct Reptiles of
+the Mesozoic period.
+</p>
+
+<p class="indent">
+As regards animal life, the <i>Protozoans</i> of the Cretaceous
+period are exceedingly numerous, and are represented by
+<i>Foraminifera</i> and <i>Sponges</i>. As we have already seen,
+the White Chalk itself is a deep-sea deposit, almost entirely
+composed of the microscopic shells of <i>Foraminifers</i>, along
+with Sponge-spicules, and organic <i>débris</i> of different
+kinds (see fig. 7). The green grains which are so abundant in several
+minor subdivisions of the Cretaceous, are also in many instances
+really casts in glauconite of the chambered shells of these minute
+organisms. A great many species of <i>Foraminifera</i> have been
+recognised in the Chalk; but the three principal genera are
+<a name="page_264"><span class="page">Page 264</span></a>
+<i>Globigerina, Rotalia</i> (fig. 187), and <i>Textularia</i>&mdash;groups
+which are likewise characteristic of the "ooze" of the Atlantic and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 472px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig187.jpg" width="472" height="161" alt="Fig. 187" />
+<br />
+Fig. 187&mdash;<i>Kotalia Boueana</i>.
+</span>
+</span>
+
+Pacific Oceans at great depths. The flints of the Chalk also commonly
+contain the shells of <i>Foraminifera</i>. The Upper Greensand
+has yielded in considerable numbers the huge <i>Foraminifera</i>
+described by Dr Carpenter under the name of <i>Parkeria</i>, the
+spherical shells of which are composed of sand-grains agglutinated
+together, and sometimes attain a diameter of two and a quarter
+inches. The Cretaceous Sponges are extremely numerous, and occur
+under a great number of varieties of shape and structure; but
+the two most characteristic genera are <i>Siphonia</i> and
+<i>Ventriculites</i>, both of which are exclusively confined to
+strata of this age. The <i>Siphoniœ</i> (fig. 188) consist of a
+pear-shaped, sometimes lobed head, supported by a longer or shorter
+stern, which breaks up at its base into a number of root-like
+processes of attachment. The water gained access to the interior
+of the Sponge by a number of minute openings covering the surface,
+and ultimately escaped by a single, large, chimney-shaped aperture
+at the summit. In some respects these sponges present a singular
+resemblance to the beautiful "Vitreous Sponges" (<i>Holtenia</i>
+or <i>Pheronema</i>) of the deep Atlantic; and, like these, they
+were probably denizens of a deep sea, The <i>Ventriculites</i>
+of the Chalk (fig. 189) is, however, a genus still more closely
+allied to the wonderful flinty Sponges, which have been shown,
+by the researches of the Porcupine, Lightning, and Challenger
+expeditions, to live half buried in the Calcareous ooze of the
+abysses of our great oceans. Many forms of this genus are known,
+having "usually the form of graceful vases, tubes, or funnels,
+variously ridged or grooved, or otherwise ornamented on the surface,
+frequently expanded above into a cup-like lip, and continued
+below into a bundle of fibrous roots. The minute structure of
+these bodies shows an extremely delicate tracery of fine tubes,
+sometimes empty, sometimes filled with loose calcareous matter
+<a name="page_265"><span class="page">Page 265</span></a>
+dyed with peroxide of iron."&mdash;(Sir Wyville Thomson.) Many of
+the Chalk sponges, originally calcareous, have been converted into
+flint subsequently; but the Ventriculites are really composed
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 125px; vertical-align:top; text-align: center;
+  margin: 4px;">
+<img src="images/fig188.jpg" width="125" height="424" alt="Fig. 188" />
+<br />
+Fig. 188.&mdash;<i>Siphonia ficus</i>. Upper Greensand. Europe.
+</span>
+
+<span style="width: 222px; vertical-align:top; text-align: center;
+  margin: 4px;">
+<img src="images/fig189.jpg" width="222" height="424" alt="Fig. 189" />
+<br />
+Fig. 189.&mdash;<i>Ventriculites simplex</i>. White Chalk. Britain.
+</span>
+
+</span>
+
+of this substance, and are therefore genuine "Siliceous Sponges,"
+like the existing Venus's Flower-Basket (<i>Euplectella</i>).
+Like the latter, the skeleton was doubtless originally composed,
+in the young state, of disconnected six-rayed spicules, which
+ultimately become fixed together to constitute a continuous
+frame-work. The sea-water, as in the recent forms, must have
+been admitted to the interior of the Sponge by numerous apertures
+on its exterior, subsequently escaping by a single large opening
+at its summit.
+</p>
+
+<p class="indent">
+Amongst the <i>Cœlenterates</i>, the "Hydroid Zoophytes" are
+represented by a species of the encrusting genus <i>Hydractinia</i>,
+the horny polypary of which is so commonly found at the present
+day adhering to the exterior of shells. The occurrence of this
+genus is of interest, because it is the first known instance in
+the entire geological series of the occurrence of an unquestionable
+Hydroid of a modern type, though many of the existing forms of
+these animals possess structures which are
+<a name="page_266"><span class="page">Page 266</span></a>
+perfectly fitted for
+preservation in the fossil condition. The corals of the Cretaceous
+series are not very numerous, and for the most part are referable
+to types such as <i>Trochocyathus, Stephanophyllia, Parasmilia,
+Synhelia</i> (fig. 190), &amp;c., which belong to the same great
+group of corals as the majority of existing forms. We have also
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 480px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig190.jpg" width="480" height="319" alt="Fig. 190" />
+<br />
+Fig. 190.&mdash;<i>Synhelia Sharpeana</i>. Chalk, England.
+</span>
+</span>
+
+a few "Tabulate Corals" (<i>Polytremacis</i>), hardly, if at all,
+generically separable from very ancient forms (<i>Heliolites</i>);
+and the Lower Greensand has yielded the remains of the little
+<i>Holocystis elegans</i>, long believed to be the last of the
+great Palæozoic group of the <i>Rugosa</i>.
+</p>
+
+<p class="indent">
+As regards the <i>Echinoderms</i>, the group of the <i>Crinoids</i>
+now exhibits a marked decrease in the number and variety of its
+types. The "stalked" forms are represented by <i>Pentacrinus</i>
+and <i>Bourgueticrinus</i>, and the free forms by Feather-stars
+like our existing <i>Comatulœ</i>; whilst a link between the
+stalked and free groups is constituted by the curious "Tortoise
+Encrinite (<i>Marsupites</i>). By far the most abundant Cretaceous
+Echinoderms, however, are Sea-urchins (<i>Echinoids</i>); though
+several Star-fishes are known as well. The remains of Sea-urchins
+are so abundant in various parts of the Cretaceous series, especially
+in the White Chalk, and are often so beautifully preserved, that
+they constitute one of the most marked features of the fauna
+of the period. From the many genera of Sea-urchins which occur
+in strata of this age, it is difficult to select characteristic
+types; but the genera <i>Galerites</i> (fig. 191), <i>Discoidea</i>
+(fig. 192), <i>Micraster, Ananchytes, Diadema, Salenia</i>, and
+<a name="page_267"><span class="page">Page 267</span></a>
+<i>Cidaris</i>, may be mentioned as being all important Cretaceous
+groups.
+</p>
+
+<p class="indent">
+Coming to the <i>Annulose Animals</i> of the Cretaceous period,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 533px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig191.jpg" width="533" height="181" alt="Fig. 191" />
+<br />
+Fig. 191.&mdash;<i>Galerites albogalerus</i>, viewed from below,
+from the side, and from above. White Chalk.
+</span>
+</span>
+
+there is little special to remark. The <i>Crustaceans</i> belong
+for the most part to the highly-organised groups of the Lobsters
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 531px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig192.jpg" width="531" height="168" alt="Fig. 192" />
+<br />
+Fig. 192.&mdash;<i>Discoidea cylindrica</i>; under, side, and
+upper aspect. Upper Greensand.
+</span>
+</span>
+
+and the Crabs (the Macrurous and Brachyurous Decapods); but there
+are also numerous little <i>Ostracodes</i>, especially in the
+fresh-water strata of the Wealden. It should further be noted
+that there occurs here a great development of the singular
+<i>Crustaceous</i> family of the Barnacles (<i>Lepadidœ</i>),
+whilst the allied family of the equally singular Acorn-shells
+(<i>Balanidœ</i>) is feebly represented as well.
+</p>
+
+<p class="indent">
+Passing on to the <i>Mollusca</i>, the class of the Sea-mats
+and Sea-mosses (<i>Polyzoa</i>) is immensely developed in the
+Cretaceous period, nearly two hundred species being known to
+occur in the Chalk. Most of the Cretaceous forms belong to the
+family of the <i>Escharidœ</i>, the genera <i>Eschara</i> and
+<i>Escharina</i> (fig. 193) being particularly well represented.
+Most of the Cretaceous <i>Polyzoans</i> are of small size, but
+some attain considerable dimensions, and many simulate Corals
+in their general form and appearance.
+</p>
+
+<p class="indent">
+<a name="page_268"><span class="page">Page 268</span></a>
+The Lamp-shells (<i>Brachiopods</i>) have now reached a further
+stage of the progressive decline, which they have been undergoing
+
+<span style="float: left; margin: 4px; width: 237px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig193.jpg" width="237" height="194" alt="Fig. 193" />
+<br />
+Fig. 193.&mdash;A small fragment of <i>Escharina Oceani</i>,
+of the natural size; and a portion of the same enlarged. Upper
+Greensand.
+</span>
+
+ever since the close of the Palæozoic period. Though
+individually not rare, especially in certain minor subdivisions of
+the series, the number of generic types has now become distinctly
+diminished, the principal forms belonging to the genera
+<i>Terebratula, Terebratella</i> (fig. 194), <i>Terebratulina,
+Rhynchonella</i>, and <i>Crania</i> (fig. 195). In the last
+mentioned of these, the shell is attached to foreign bodies by
+the substance of one of the valves (the ventral), whilst the other
+or free valve is more or less limpet-shaped. All the above-mentioned
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig194.jpg" width="531" height="209" alt="Fig. 194" />
+<br />
+Fig. 194.&mdash;<i>Terebratella Astieriana</i>. Gault.
+</span>
+</span>
+
+genera are in existence at the present day; and one
+<i>species</i>&mdash;namely, <i>Terebratulina
+striata</i>&mdash;appears to be undistinguishable from one now
+living&mdash;the <i>Terebratulina caputserpentis</i>.
+</p>
+
+<p class="indent">
+Whilst the Lamp-shells are slowly declining, the Bivalves
+(<i>Limellibranchs</i>) are greatly developed, and are amongst
+the most abundant and characteristic fossils of the Cretaceous
+period. In the great river-deposit of the Wealden, the Bivalves
+are forms proper to fresh water, belonging to the existing
+River-mussels (<i>Unio</i>), <i>Cyrena</i> and <i>Cyclas</i>;
+but most of the Cretaceous Lamellibranchs are marine. Some of
+the most abundant and characteristic of these belong to the great
+family of the Oysters (<i>Ostreidœ</i>). Amongst these are
+the genera <i>Gryphtœa</i> and <i>Exogyra</i>, both of which
+we have seen to occur
+<a name="page_269"><span class="page">Page 269</span></a>
+abundantly in the Jurassic; and there are
+also numerous true Oysters (<i>Ostrea</i>, fig. 196) and Thorny
+Oysters (<i>Spondylus</i>, fig. 197). The genus <i>Trigonia</i>,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 579px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig195.jpg" width="579" height="212" alt="Fig. 195" />
+<br />
+Fig. 195.&mdash;<i>Crania Ignabergensis</i>. The left-hand
+figure shows the perfect shell, attached by its ventral valve
+to a foreign body; the middle figure shows the exterior of the
+limpet-shaped dorsal valve; and the right-hand figure represents
+the interior of the attached valve. White Chalk.
+</span>
+</span>
+
+so characteristic of the Mesozoic deposits in general, is likewise
+well represented in the Cretaceous strata. No single genus of
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 575px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig196.jpg" width="525" height="268" alt="Fig. 196" />
+<br />
+Fig. 196.&mdash;<i>Ostrea Couloni</i>. Lower Greensand.
+</span>
+</span>
+
+Bivalves is, however, so highly characteristic of the Cretaceous
+period as <i>Inoceramus</i>, a group belonging to the family of the
+Pearl-mussels (<i>Aviculidœ</i>). The shells of this genus
+(fig. 198) have the valves unequal in size, the larger valve often
+being much twisted, and both valves being marked with radiating
+ribs or concentric furrows. The hinge-line is long and straight,
+with numerous pits for the attachment of the ligament which serves
+to open the shell. Some of the <i>Inocerami</i> attain a length
+of two or three feet, and fragments of the shell are often found
+perforated by boring
+<a name="page_270"><span class="page">Page 270</span></a>
+Sponges. Another extraordinary family of
+Bivalves, which is exclusively confined to the Cretaceous rocks, is
+that of the <i>Hippuritidœ</i>. All the members of this group
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 497px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig197.jpg" width="497" height="217" alt="Fig. 197" />
+<br />
+Fig. 197.&mdash;<i>Spondylus spinosus</i>. White Chalk.
+</span>
+</span>
+
+(fig. 199) were attached to foreign objects, and lived associated
+in beds, like Oysters. The two valves of the shell are always
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 497px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig198.jpg" width="459" height="163" alt="Fig. 198" />
+<br />
+Fig. 198.&mdash;<i>Inoceramus sulcatus</i>. Gault.
+</span>
+</span>
+
+altogether unlike in sculpturing, appearance, shape, and size;
+and the cast of the interior of the shell is often extremely
+unlike the form of the outer surface. The type-genus of the family
+is <i>Hippurites</i> itself (fig. 199), in which the shell is in
+the shape of a straight or slightly-twisted horn, sometimes a
+foot or more in length, constituted by the attached lower valve,
+and closed above by a small lid-like free upper valve. About
+a hundred species of the family of the <i>Hippuritidœ</i>
+are known, all of these being Cretaceous, and occurring in Britain
+(one species only), in Southern Europe, the West Indies, North
+America, Algeria, and Egypt. Species of this family occur in
+such numbers in certain compact marbles in the south of Europe,
+of the age of the Upper Cretaceous (Lower Chalk), as to have
+given origin to the name of "Hippurite Limestones," applied to
+these strata.
+</p>
+
+<p class="indent">
+<a name="page_271"><span class="page">Page 271</span></a>
+The Univalves (<i>Gasteropods</i>) of the Cretaceous period are
+not very numerous, nor particularly remarkable. Along with species
+of the persistent genus <i>Pleurotomaria</i> and the Mesozoic
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 230px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig199.jpg" width="230" height="442" alt="Fig. 199" />
+<br />
+Fig. 199.&mdash;<i>Hippurites Toucasiana</i>. A large individual,
+with two smaller ones attached to it. Upper Cretaceous, South
+of Europe.
+</span>
+
+<span style="width: 168px; vertical-align:bottom; text-align: center;
+  margin: 4px;">
+<img src="images/fig200.jpg" width="168" height="534" alt="Fig. 200" />
+<br />
+Fig. 200.&mdash;<i>Voluta elongata</i>. White Chalk.
+</span>
+
+</span>
+
+<i>Nerinœa</i>, we meet with examples of such modern types
+as <i>Turritella</i> and <i>Natica</i>, the Staircase-shells
+(<i>Solarium</i>), the Wentle-traps (<i>Scalaria</i>), the
+Carrier-shells (<i>Phorus</i>), &amp;c. Towards the close of the
+Cretaceous period, and especially in such transitional strata
+as the Maestricht beds, the Faxöe Limestone, and the Pisolitic
+Limestone of France, we meet with a number of carnivorous
+("siphonostomatous") Univalves, in which the mouth of the shell is
+notched or produced into a canal. Amongst these it is interesting
+to recognise examples of such existing genera as the Volutes
+(<i>Voluta</i>, fig. 200), the Cowries (<i>Cyprœa</i>), the
+Mitre-shells (<i>Mitra</i>), the Wing - shells (<i>Strombus</i>),
+the Scorpion-shells (<i>Pteroceras</i>), &amp;c.
+</p>
+
+<p class="indent">
+<a name="page_272"><span class="page">Page 272</span></a>
+Upon the whole, the most characteristic of all the Cretaceous
+Molluscs are the <i>Cephalopods</i>, represented by the remains
+of both <i>Tetrabranchiate</i> and <i>Dibranchiate</i> forms.
+Amongst the former, the long-lived genus <i>Nautilus</i> (fig.
+201) again reappears, with its involute shell, its capacious
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 495px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig201.jpg" width="495" height="245" alt="Fig. 201" />
+<br />
+Fig. 201.&mdash;Different views of <i>Nautilus Danicus</i>.
+Faxöe Limestone (Upper Cretaceous), Denmark.
+</span>
+</span>
+
+body-chamber, its simple septa between the air-chambers, and its
+nearly or quite central siphuncle. The majority of the chambered
+<i>Cephalopods</i> of the Cretaceous belong, however, to the
+complex and beautiful family of the <i>Ammonitidœ</i>, with
+their elaborately folded and lobed septa and dorsally-placed
+siphuncle. This family disappears wholly at the close of the
+Cretaceous period; but its approaching extinction, so far from
+being signalised by any slow decrease and diminution in the number
+of specific or generic types, seems to have been attended by the
+development of whole series of new forms. The genus <i>Ammonites</i>
+itself, dating from the Carboniferous, has certainly passed its
+prime, but it is still represented by many species, and some of
+these attained enormous dimensions (two or three feet in diameter).
+The genus <i>Ancyloceras</i> (fig. 202), though likewise of more
+ancient origin (Jurassic), is nevertheless very characteristic
+of the Cretaceous. In this genus the first portion of the shell
+is in the form of a flat spiral, the coils of which are not in
+contact; and its last portion is produced at a tangent, becoming
+ultimately bent back in the form of a crosier. Besides these
+pre-existent types, the Cretaceous rocks have yielded a great
+number of entirely new forms of the <i>Ammonitidœ</i>, which
+are not known in any deposits of earlier or later date. Amongst the
+more important of these may be mentioned <i>Crioceras, Turrilites,
+Scaphites, Hamites,</i>
+<a name="page_273"><span class="page">Page 273</span></a>
+<i>Ptychoceras</i>, and <i>Baulites</i>. In the
+genus <i>Crioceras</i> (fig. 204, <i>d</i>), the shell consists
+of an open spiral, the volutions of which are not in contact,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 528px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig202.jpg" width="528" height="176" alt="Fig. 202" />
+<br />
+Fig. 202.&mdash;<i>Ancyloceras Matheronianus</i>. Gault.
+</span>
+</span>
+
+thus resembling a partially-unrolled <i>Ammonite</i> or the inner
+portion of an <i>Ancyloceras</i>. In <i>Turrilites</i> (fig.
+203), the shell is precisely like that of the <i>Ammonite</i>
+in its structure; but instead of forming a flat spiral, it is
+coiled into an elevated turreted shell, the whorls of which are
+in contact with one another. In the genus <i>Scaphites</i> (fig.
+204, <i>e</i>), the shell resembles that of <i>Ancyloceras</i> in
+consisting of a series of volutions coiled into a flat spiral,
+the last being detached from the others, produced, and ultimately
+bent back in the form of a crosier; but the whorls of the enrolled
+part of the shell are in contact, instead of being separate as
+in the latter. In the genus <i>Hamites</i> (fig. 204, <i>f</i>),
+the shell is an extremely elongated cone, which is bent upon
+itself more than once, in a hook-like manner, all the volutions
+being separate. The genus <i>Ptychoteras</i> (fig. 204, <i>a</i>)
+is very like <i>Hamites</i>, except that the shell is only bent
+once; and the two portions thus bent are in contact with one
+another. Lastly, in the genus <i>Baculites</i> (fig. 204, <i>b</i>
+and <i>c</i>) the shell is simply a straight elongated cone, not
+bent in any way, but possessing the folded septa which characterise
+the whole Ammonite family. The <i>Baculite</i> is the simplest of all
+the forms of the <i>Ammonitidœ</i>; and all the other forms,
+however complex, may be regarded as being simply produced by the
+bending or folding of such a conical septate shell in different
+ways. The <i>Baculite</i>, therefore, corresponds, in the series of
+the <i>Ammonitidœ</i>, to the <i>Orthoceras</i> in the series
+of the <i>Nautilidœ</i>. All the above-mentioned genera are
+characteristically, or exclusively, Cretaceous, and they are
+accompanied by a number of other allied forms, which cannot be
+noticed here. Not a single one of these genera, further, has hitherto
+been detected in any strata higher than the Cretaceous. We may
+therefore consider that these wonderful, varied, and elaborate
+<a name="page_274"><span class="page">Page 274</span></a>
+forms of <i>Ammonitidœ</i> constitute one of the most
+conspicuous features in the life of the Chalk period.
+</p>
+
+<p class="indent">
+The <i>Dibranchiate Cephalopods</i> are represented partly by
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 181px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig203.jpg" width="181" height="674" alt="Fig. 203" />
+<br />
+Fig. 203.&mdash;<i>Turrilites catenatus</i>. The lower figure
+represents the entire shell; the upper figure represents the base
+of the shell seen from below. Gault.
+</span>
+
+<span style="width: 319px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig204.jpg" width="319" height="674" alt="Fig. 204" />
+<br />
+Fig. 204.&mdash;<i>a, Ptychoceras Emericianum</i>,
+reduced&mdash;Lower Greensand; <i>b, Baculites anceps</i>,
+reduced&mdash;Chalk; <i>c</i>, Portion of the same, showing the
+folded edges of the septa; <i>d, Crioceras cristatum</i>,
+reduced&mdash;Gault; <i>e, Scaphites œqualis</i>, natural
+size&mdash;Chalk; <i>f, Hamites rotundus</i>, restored&mdash;Gault.
+</span>
+
+</span>
+
+the beak-like jaws of unknown species of Cuttle-fishes and partly
+by the internal skeletons of Belemnites. Amongst the latter, the
+genus <i>Belemnites</i> itself holds its place in the lower part
+<a name="page_275"><span class="page">Page 275</span></a>
+of the Cretaceous series; but it disappears in the upper portion
+of the series, and its place is taken by the nearly-allied genus
+<i>Belemnitella</i> (fig. 205), distinguished by the possession
+of a straight fissure in the upper end of the guard. This also
+
+<span style="float: right; margin: 4px; width: 56px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig205.jpg" width="56" height="289" alt="Fig. 205" />
+<br />
+Fig. 205.&mdash;Guard of <i>Belemnitella mucronata</i>.
+</span>
+
+disappears at the close of the Cretaceous period; and no member of
+the great Mesozoic family of the <i>Belemnitidœ</i> has
+hitherto been discovered in any Tertiary deposit, or is known to
+exist at the present day.
+</p>
+
+<p class="indent">
+Passing on next to the <i>Vertebrate Animals</i> of the Cretaceous
+period, we find the <i>Fishes</i> represented as before by the
+Ganoids and the Placoids, to which, however, we can now add the
+first known examples of the great group of the <i>Bony Fishes</i>
+or <i>Teleosteans</i>, comprising the great majority of existing
+forms. The <i>Ganoid</i> fishes of the Cretaceous (<i>Lepidotus,
+Pycnodus</i>, &amp;c.) present no features of special interest.
+Little, also, need be said about the <i>Placoid</i> fishes of this
+period. As in the Jurassic deposits, the remains of these consist
+partly of the teeth of genuine Sharks (<i>Lamna, Odontaspis</i>,
+&amp;c.) and partly of the teeth and defensive spines of Cestracionts,
+such as the living Port-Jackson Shark. The pointed and sharp-edged
+teeth of true Sharks are very abundant in some beds, such as
+the Upper Greensand, and are beautifully preserved. The teeth
+of some forms (<i>Carcharias</i>, &amp;c.) attain occasionally a
+length of three or four inches, and indicate the existence in the
+Cretaceous seas of huge predaceous fishes, probably larger than
+any existing Sharks. The remains of <i>Cestracionts</i> consist
+partly of the flattened teeth of genera such as <i>Acrodus</i>
+and <i>Ptychodus</i> (the latter confined to rocks of this age),
+and partly of the pointed teeth of <i>Hybodus</i>, a genus which
+dates from the Trias. In this genus the teeth (fig. 206) consist
+of a principal central cone, flanked by minor lateral cones; and
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 94px; vertical-align:bottom; text-align: center;
+  margin: 4px;">
+<img src="images/fig206.jpg" width="94" height="125" alt="Fig. 206" />
+<br />
+Fig. 206.&mdash;Tooth of <i>Hybodus</i>.
+</span>
+
+<span style="width: 423px; vertical-align:bottom; text-align: center;
+  margin: 4px;">
+<img src="images/fig207.jpg" width="423" height="56" alt="Fig. 207" />
+<br />
+Fig. 207.&mdash;Fin-spine of <i>Hybodus</i>. Lower Greensand.
+</span>
+
+</span>
+
+the fin-spines (fig. 207) are longitudinally grooved, and carry
+a series of small spines on their hinder or concave margin. Lastly,
+<a name="page_276"><span class="page">Page 276</span></a>
+the great modern
+order of the Bony Fishes or <i>Teleosteans</i> makes its first
+appearance in the Upper Cretaceous rocks, where it is represented by
+forms belonging to no less than three existing groups&mdash;namely,
+the Salmon family (<i>Salmonidœ</i>), the Herring family
+(<i>Clupeidœ</i>), and the Perch family (<i>Percidœ</i>).
+All these fishes have thin, horny, overlapping scales, symmetrical
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 490px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig208.jpg" width="490" height="434" alt="Fig. 208" />
+<br />
+Fig. 208.&mdash;1, <i>Beryx Lewesiensis</i>, a Percoid fish from
+the Chalk; 2, <i>Osmeroides Mantelli</i>, a Salmonoid fish from
+the Chalk.
+</span>
+</span>
+
+("homocercal") tails, and bony skeletons. The genus <i>Beryx</i>
+(fig. 208, 1) is one represented by existing species at the present
+day, and belongs to the Perch family. The genus <i>Osmeroides</i>,
+again (fig. 208, 2), is supposed to be related to the living Smelts
+(<i>Osmerus</i>), and, therefore, to belong to the Salmon tribe.
+</p>
+
+<p class="indent">
+No remains of <i>Amphibians</i> have hitherto been detected in any
+part of the Cretaceous series; but <i>Reptiles</i> are extremely
+numerous, and belong to very varied types. As regards the great
+extinct groups of Reptiles which characterise the Mesozoic period
+as a whole, the huge "Enaliosaurs" or "Sea-Lizards" are still
+represented by the <i>Ichthyosaur</i> and the <i>Plesiosaur</i>.
+Nearly allied to the latter of these is the <i>Elasmosaurus</i>
+of the American Cretaceous, which combined
+<a name="page_277"><span class="page">Page 277</span></a>
+the long tail of the Ichthyosaur with the long neck of the
+Plesiosaur. The length of this monstrous Reptile could not have
+been less than fifty feet, the neck consisting of over sixty
+vertebræ and measuring over twenty feet in length. The
+extraordinary Flying Reptiles of the Jurassic are likewise well
+represented in the Cretaceous rocks by species of the genus
+<i>Pterodactylus</i> itself, and these later forms are much more
+gigantic in their dimensions than their predecessors. Thus some of
+the Cretaceous Pterosaurs seem to have had a spread of wing of from
+twenty to twenty-five feet, more than realising the "Dragons" of
+fable in point of size. The most remarkable, however, of the
+Cretaceous <i>Pterosaurs</i> are the forms which have recently
+been described by Professor Marsh under the generic title of
+<i>Pteranodon</i>. In these singular forms&mdash;so far only known
+as American&mdash;the animal possessed a skeleton in all respects
+similar to that of the typical Pterodactyles, except that the jaws
+are completely destitute of teeth. There is, therefore, the
+strongest probability that the jaws were encased in a horny sheath,
+thus coming to resemble the beak of a Bird. Some of the recognised
+species of <i>Pteranodon</i> are very small; but the skull of one
+species (<i>P. Longiceps</i>) is not less than a yard in length,
+and there are portions of the skull of another species which would
+indicate a length of four feet for the cranium. These measurements
+would point to dimensions larger than those of any other known
+Pterosaurs.
+</p>
+
+<p class="indent">
+The great Mesozoic order of the <i>Deinosaurs</i> is largely
+represented in the Cretaceous rocks, partly by genera which
+previously existed in the Jurassic period, and partly by entirely new
+types. The great delta-deposit of the Wealden, in the Old World, has
+yielded the remains of various of these huge terrestrial Reptiles,
+and very many others have been found in the Cretaceous deposits
+of North America. One of the most celebrated of the Cretaceous
+Deinosaurs is the <i>Iguanodon</i>, so called from the curious
+resemblance of its teeth to those of the existing but comparatively
+diminutive <i>Iguana</i>. The teeth (fig. 209) are soldered to the
+inner face of the jaw, instead of being sunk in distinct sockets;
+and they have the form of somewhat flattened prisms, longitudinally
+ridged on the outer surface, with an obtusely triangular crown,
+and having the enamel crenated on one or both sides. They present
+the extraordinary feature that the crowns became worn down flat
+by mastication, showing that the <i>Iguanodon</i> employed its
+teeth in actually chewing and triturating the vegetable matter
+on which it fed. There can therefore be no doubt but that the
+<i>Iguanodon</i>, in spite of its immense bulk, was an herbivorous
+Reptile, and
+<a name="page_278"><span class="page">Page 278</span></a>
+lived principally on the foliage of the Cretaceous forests
+amongst which it dwelt. Its size has been variously estimated
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 426px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig209.jpg" width="426" height="347" alt="Fig. 209" />
+<br />
+Fig. 209.&mdash;Teeth of Iguanodon Mantellii. Wealden, Britain.
+</span>
+</span>
+
+at from thirty to fifty feet, the thigh-bone in large examples
+measuring nearly five feet in length, with a circumference of
+twenty-two inches in its smallest part. With the strong and massive
+hind-limbs are associated comparatively weak and small fore-limbs;
+and there seems little reason to doubt that the <i>Iguanodon</i>
+must have walked temporarily or permanently upon its hind-limbs,
+after the manner of a Bird. This conjecture is further supported
+by the occurrence in the strata which contain the bones of the
+<i>Iguanodon</i> of gigantic three-toed foot-prints, disposed
+<i>singly</i> in a double track. These prints have undoubtedly
+been produced by some animal walking on two legs; and they can
+hardly, with any probability, be ascribed to any other than this
+enormous Reptile. Closely allied to the <i>Iguanodon</i> is the
+<i>Hadrosaurus</i> of the American Cretaceous, the length of
+which is estimated at twenty-eight feet. <i>Iguanodon</i> does
+not appear to have possessed any integumentary skeleton; but the
+great <i>Hylœosaurus</i> of the Wealden seems to have been
+furnished with a longitudinal crest of large spines running down
+the back, similar to that which is found in the comparatively
+small Iguanas of the present day. The <i>Megalosaurus</i> of
+the Oolites continued to exist in the Cretaceous period; and,
+as we have previously seen, it was carnivorous in its habits.
+The American <i>Lœlaps</i> was also carnivorous, and, like
+the Megalosaur,
+<a name="page_279"><span class="page">Page 279</span></a>
+which it very closely resembles, appears to have walked upon its
+hind-legs, the fore-limbs being disproportionately small.
+</p>
+
+<p class="indent">
+Another remarkable group of Reptiles, exclusively confined to
+the Cretaceous series, is that of the <i>Mosasauroids</i>, so
+called from the type-genus <i>Mosasaurus</i>. The first species
+of <i>Mosasaurus</i> known to science was the <i>M. Camperi</i>
+(fig. 210), the skull of which&mdash;six feet in length&mdash;was
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 508px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig210.jpg" width="508" height="314" alt="Fig. 210" />
+<br />
+Fig. 210.&mdash;Skull of <i>Mosasaurus Camperi</i>, greatly
+reduced. Maestricht Chalk.
+</span>
+</span>
+
+discovered in 1780 in the Maestricht Chalk at Maestricht. As this
+town stands on the river Meuse, the name of <i>Mosasaurus</i>
+("Lizard of the Meuse") was applied to this immense Reptile. Of
+late years the remains of a large number of Reptiles more or less
+closely related to <i>Mosasaurus</i>, or absolutely belonging to
+it, have been discovered in the Cretaceous deposits of North
+America, and have been described by Professors Cope and Marsh.
+All the known forms of this group appear to have been of large
+size&mdash;one of them, <i>Mosasaurus princeps</i>, attaining
+the length of seventy-five or eighty feet, and thus rivalling
+the largest of existing Whales in its dimensions. The teeth in
+the "Mosasauroids" are long, pointed, and slightly curved; and
+instead of being sunk in distinct sockets, they are firmly
+amalgamated with the jaws, as in modern Lizards. The palate
+also carried teeth, and the lower jaw was so constructed as to
+allow of the mouth being opened to an immense width, somewhat
+as in the living Serpents. The body was long and snake-like,
+with a very long tail, which is laterally compressed, and must
+have served as a powerful swimming-apparatus. In addition to
+this, both pairs of limbs have the bones connecting them with
+<a name="page_280"><span class="page">Page 280</span></a>
+the trunk greatly shortened; whilst the digits were enclosed in
+the integuments, and constituted paddles, closely resembling in
+structure the "flippers" of Whales and Dolphins. The neck is
+sometimes moderately long, but oftener very short, as the great
+size and weight of the head would have led one to anticipate.
+Bony plates seem in some species to have formed an at any rate
+partial covering to the skin; but it is not certain that these
+integumentary appendages were present in all. Upon the whole,
+there can be no doubt but that the Mosasauroid Reptiles&mdash;the
+true "Sea-serpents" of the Cretaceous period&mdash;were
+essentially aquatic in their habits, frequenting the sea, and
+only occasionally coming to the land.
+</p>
+
+<p class="indent">
+The "Mosasauroids" have generally been regarded as a greatly
+modified group of the Lizards (<i>Lacertilia</i>). Whether this
+reference be correct or not&mdash;and recent investigations render
+it dubious&mdash;the Cretaceous rocks have yielded the remains of
+small Lizards not widely removed from existing forms. The recent
+order of the <i>Chelonians</i> is also represented in the
+
+<span style="float: left; margin: 4px; width: 311px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig211.jpg" width="311" height="429" alt="Fig. 211" />
+<br />
+Fig. 211.&mdash;Carapace of <i>Chelone Benstedi</i>. Lower Chalk.
+(After Owen.)
+</span>
+
+Cretaceous rocks, by forms closely resembling living types. Thus
+the fresh-water deposits of the Wealden have yielded examples of
+the "Terrapins" or "Mud-Turtles" (<i>Emys</i>); and the marine
+Cretaceous strata have been found to contain the remains of various
+species of Turtles, one of which is here figured (fig. 211). No
+true Serpents (<i>Ophidia</i>) have as yet been detected in the
+Cretaceous rocks; and this order does not appear to have come
+into existence till the Tertiary period. Lastly, true Crocodiles
+are known to have existed in considerable numbers in the Cretaceous
+period. The oldest of these occur in the fresh-water deposit of the
+Wealden; and they differ from
+<a name="page_281"><span class="page">Page 281</span></a>
+the existing forms of
+the group in the fact that the bodies of the vertebræ, like
+those of the Jurassic Crocodiles, are bi-concave, or hollowed out
+at both ends. In the Greensand of North America, however, occur
+the remains of Crocodiles which agree with all the living species
+in having the bodies of the vertebræ in the region of the
+back hollowed out in front and convex behind.
+</p>
+
+<p class="indent">
+<i>Birds</i> have not hitherto been shown, with certainty, to
+have existed in Europe during the Cretaceous period, except in
+a few instances in which fragmentary remains belonging to this
+class have been discovered. The Cretaceous deposits of North
+America have, however, been shown by Professor Marsh to contain
+a considerable number of the remains of Birds, often in a state
+of excellent preservation. Some of these belong to Swimming or
+Wading Birds, differing in no point of special interest from
+modern birds of similar habits. Others, however, exhibit such
+extraordinary peculiarities that they merit more than a passing
+notice. One of the forms in question constitutes the genus
+<i>Ichthyornis</i> of Marsh, the type-species of which (<i>I.
+Dispar</i>) was about as large as a Pigeon. In two remarkable
+respects, this singular Bird differs from all known living members
+of the class. One of these respects concerns the jaws, both of
+which exhibit the Reptilian character of being armed with numerous
+small pointed <i>teeth</i> (fig. 212, <i>a</i>), sunk in distinct
+sockets. No existing bird possesses teeth; and this character
+forcibly recalls the Bird-like Pterosaurs, with their toothed
+jaws. <i>Ichthyornis</i>, however, possessed fore-limbs constructed
+strictly on the type of the "wing" of the living Birds; and it
+cannot, therefore, be separated from this class. Another
+extraordinary peculiarity of <i>Ichthyornis</i> is, that the
+bodies of the <i>vertebrie</i> (fig. 212, <i>c</i>) were
+<i>bi-concave</i>, as is the case with many extinct Reptiles and
+almost all Fishes, but as does not occur in any living Bird. There
+can be little doubt that <i>Ichthyornis</i> was aquatic in its
+habits, and that it lived principally upon fishes; but its powerful
+wings at the same time indicate that it was capable of prolonged
+flight. The tail of <i>Ichthyornis</i> has, unfortunately, not
+been discovered; and it is at present impossible to say whether
+this resembled the tail of existing Birds, or whether it was
+elongated and composed of separate vertebræ, as in the
+Jurassic <i>Archœopteryx</i>.
+</p>
+
+<p class="indent">
+Still more wonderful than <i>Ichthyornis</i> is the marvellous
+bird described by Marsh under the name of <i>Hesperornis
+regalis</i>. This presents us with a gigantic diving bird,
+somewhat resembling the existing "Loons" (<i>Colymbus</i>), but
+agreeing with <i>Ichthyornis</i> in having the jaws furnished
+<a name="page_282"><span class="page">Page 282</span></a>
+with conical, recurved, pointed teeth (fig. 212, <i>b</i>).
+Hence these forms are grouped together in a new sub-class, under
+the name of <i>Odontornithes</i> or "Toothed Birds." The teeth
+of <i>Hesperornis</i> (fig. 212, <i>d</i>) resemble those of
+<i>Ichthyornis</i> in their general form; but instead of being
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 525px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig212.jpg" width="525" height="373" alt="Fig. 212" />
+<br />
+Fig. 212.&mdash;Toothed Birds (<i>Odontornithes</i>) of the
+Cretaceous Rocks of America. <i>a</i>. Left lower jaw of
+<i>Ichthyornis dispar</i>, slightly enlarged; <i>b</i>, Left
+lower jaw of <i>Hesperornis regalis</i>, reduced to nearly
+one-fourth of the natural size; <i>c</i>. Cervical vertebra
+of <i>Ichthyornis dispar</i>, front view, twice the natural
+size; <i>c'</i>, Side view of the same; <i>d</i>, Tooth of
+<i>Hesperornis regalis</i>, enlarged to twice the natural
+size. (After Marsh.)
+</span>
+</span>
+
+sunk in distinct sockets, they are simply implanted in a deep
+continuous groove in the bony substance of the jaw. The front of
+the upper jaw does not carry teeth, and was probably encased in
+a horny beak. The breast-bone is entirely destitute of a central
+ridge or keel, and the wings are minute and quite rudimentary;
+so that <i>Hesperornis</i>, unlike <i>Ichthyornis</i>, must have
+been wholly deprived of the power of flight, in this respect
+approaching the existing Penguins. The tail consists of about
+twelve vertebræ, of which the last three or four are amalgamated
+to form a flat terminal mass, there being at the same time clear
+indications that the tail was capable of up and down movement
+in a vertical plane, this probably fitting it to serve as a
+swimming-paddle or rudder. The legs were powerfully constructed,
+and the feet were adapted to assist the bird in rapid motion through
+the water. The known remains of <i>Hesperornis regalis</i> prove
+it to have been a swimming and diving bird, of larger dimensions
+<a name="page_283"><span class="page">Page 283</span></a>
+than any of the aquatic members of the class of Birds with which
+we are acquainted at the present day. It appears to have stood
+between five and six feet high, and its inability to fly is fully
+compensated for by the numerous adaptations of its structure to a
+watery life. Its teeth prove it to have been carnivorous in its
+habits, and it probably lived upon fishes. It is a curious fact
+that two Birds agreeing with one another in the wholly abnormal
+character of possessing teeth, and in other respects so entirely
+different, should, like <i>Ichthyornis</i> and <i>Hesperornis</i>,
+have lived not only in the same geological period, but also in the
+same geographical area; and it is equally curious that the area
+inhabited by these toothed Birds should at the same time have been
+tenanted by winged and bird-like Reptiles belonging to the toothed
+genus <i>Pterodactylus</i> and the toothless genus <i>Pteranodon</i>.
+</p>
+
+<p class="indent">
+No remains of <i>Mammals</i>, finally, have as yet been detected
+in any sedimentary accumulations of Cretaceous age.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following list comprises some of the more important works and
+memoirs which may be consulted with reference to the Cretaceous
+strata and their fossil contents:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Memoirs of the Geological Survey of Great Britain.'</td></tr>
+<tr><td class="right" valign="top">(2)</td>
+ <td>'Geology of England and Wales.' Conybeare and
+  Phillips.</td></tr>
+<tr><td class="right" valign="top">(3)</td>
+ <td>'Geology of Yorkshire,' vol. ii. Phillips.</td></tr>
+<tr><td class="right" valign="top">(4)</td>
+ <td>'Geology of Oxford and the Thames Valley.' Phillips.</td></tr>
+<tr><td class="right" valign="top">(5)</td>
+ <td>'Geological Excursions through the Isle of Wight.'
+  Mantell.</td></tr>
+<tr><td class="right" valign="top">(6)</td>
+ <td>'Geology of Sussex.' Mantell.</td></tr>
+<tr><td class="right" valign="top">(7)</td>
+ <td>'Report on Londonderry,' &amp;c. Portlock.</td></tr>
+<tr><td class="right" valign="top">(8)</td>
+ <td>'Recherches sur le Terrain Crétacé
+  Supérieur de l'Angleterre et de l'Irlande.'
+  Barrois.</td></tr>
+<tr><td class="right" valign="top">(9)</td>
+ <td>"Geological Survey of Canada"&mdash;'Report of Progress,
+  1872-73.'</td></tr>
+<tr><td class="right" valign="top">(10)</td>
+ <td>'Geological Survey of California.' Whitney.</td></tr>
+<tr><td class="right" valign="top">(11)</td>
+ <td>'Geological Survey of Montana, Idaho, Wyoming, and Utah.'
+  Hayden and Meek.</td></tr>
+<tr><td class="right" valign="top">(12)</td>
+ <td>'Report on Geology,' &amp;c. (British North American
+  Boundary Commission). G. M. Dawson.</td></tr>
+<tr><td class="right" valign="top">(13)</td>
+ <td>'Manual of Geology.' Dana.</td></tr>
+<tr><td class="right" valign="top">(14)</td>
+ <td>'Lethæa Rossica.' Eichwald.</td></tr>
+<tr><td class="right" valign="top">(15)</td>
+ <td>'Petrefacta Germaniæ.' Goldfuss.</td></tr>
+<tr><td class="right" valign="top">(16)</td>
+ <td>'Fossils of the South Downs.' Mantell.</td></tr>
+<tr><td class="right" valign="top">(17)</td>
+ <td>'Medals of Creation.' Mantell.</td></tr>
+<tr><td class="right" valign="top">(18)</td>
+ <td>'Mineral Conchology.' Sowerby.</td></tr>
+<tr><td class="right" valign="top">(19)</td>
+ <td>'Lethæa Geognostica.' Bronn.</td></tr>
+<tr><td class="right" valign="top">(20)</td>
+ <td>'Malacostracous Crustacea of the British Cretaceous
+  Formation' (Palæontographical Society). Bell.</td></tr>
+<tr><td class="right" valign="top">(21)</td>
+ <td>'Brachiopoda of the Cretaceous Formation'
+  (Palæontographical Society). Davidson.</td></tr>
+<tr><td class="right" valign="top">(22)</td>
+ <td>'Corals of the Cretaceous Formation'
+  (Palæontographical Society). Milne-Edwards and
+  Haime.</td></tr>
+<tr><td class="right" valign="top">
+<a name="page_284"><span class="page">Page 284</span></a>
+  (23)</td>
+ <td>'Supplement to the Fossil Corals' (Palæontographical
+  Society). Martin Duncan.</td></tr>
+<tr><td class="right" valign="top">(24)</td>
+ <td>'Echinodermata or the Cretaceous Formation'
+  (Palæontographical Society). Wright.</td></tr>
+<tr><td class="right" valign="top">(25)</td>
+ <td>'Monograph of the Belemnitidæ' (Palæontographical
+  Society). Phillips.</td></tr>
+<tr><td class="right" valign="top">(26)</td>
+ <td>'Monograph of the Trigoniæ' (Palæontographical
+  Society). Lycett.</td></tr>
+<tr><td class="right" valign="top">(27)</td>
+ <td>'Fossil Cirripedes' (Palæontographical Society).
+  Darwin.</td></tr>
+<tr><td class="right" valign="top">(28)</td>
+ <td>'Fossil Mollusca of the Chalk of Britain'
+  (Palæontographical Society). Sharpe.</td></tr>
+<tr><td class="right" valign="top">(29)</td>
+ <td>'Entomostraca of the Cretaceous Formation'
+  (Palæontographical Society). Rupert Jones.</td></tr>
+<tr><td class="right" valign="top">(30)</td>
+ <td>'Monograph of the Fossil Reptiles of the Cretaceous
+  Formation' (Palæontographical Society). Owen.</td></tr>
+<tr><td class="right" valign="top">(31)</td>
+ <td>'Manual of Palæontology.' Owen.</td></tr>
+<tr><td class="right" valign="top">(32)</td>
+ <td>'Synopsis of Extinct Batrachia and Reptilia.' Cope.</td></tr>
+<tr><td class="right" valign="top">(33)</td>
+ <td>"Structure of the Skull and Limbs in Mosasauroid
+  Reptiles"&mdash;'American Journ. Sci. and Arts, 1872.'
+  Marsh.</td></tr>
+<tr><td class="right" valign="top">(34)</td>
+ <td>"On Odontornithes"&mdash;'American Journ. Sci. and Arts,
+  1875.' Marsh.</td></tr>
+<tr><td class="right" valign="top">(35)</td>
+ <td>'Ossemens Fossiles.' Cuvier.</td></tr>
+<tr><td class="right" valign="top">(36)</td>
+ <td>'Catalogue of Ornithosauria.' Seeley.</td></tr>
+<tr><td class="right" valign="top">(37)</td>
+ <td>'Paléontologie Fran&ccedil;aise.' D'Orbigny.</td></tr>
+<tr><td class="right" valign="top">(38)</td>
+ <td>'Synopsis des Echinides fossiles.' Desor.</td></tr>
+<tr><td class="right" valign="top">(39)</td>
+ <td>'Cat. Raisonné des Echinides.' Agassiz and
+  Desor.</td></tr>
+<tr><td class="right" valign="top">(40)</td>
+ <td>"Echinoids"&mdash;'Decades of the Geol. Survey of Britain.'
+  E. Forbes.</td></tr>
+<tr><td class="right" valign="top">(41)</td>
+ <td>'Paléontologie Fran&ccedil;aise.' Cotteau.</td></tr>
+<tr><td class="right" valign="top">(42)</td>
+ <td>'Versteinerungen der Böhmischen Kreide-formation.'
+  Reuss.</td></tr>
+<tr><td class="right" valign="top">(43)</td>
+ <td>"Cephalopoda, Gasteropoda, Pelecypoda, Brachiopoda; &amp;c.,
+  of the Cretaceous Rocks of India"&mdash;'Palæontologica
+  Indica,' ser. i., iii., v., vi., viii. Stoliczka.</td></tr>
+<tr><td class="right" valign="top">(44)</td>
+ <td>"Cretaceous Reptiles of the United States"&mdash;'Smithsonian
+  Contributions to Knowledge,' vol. xiv. Leidy.</td></tr>
+<tr><td class="right" valign="top">(45)</td>
+ <td>'Invertebrate Cretaceous, and Tertiary Fossils of the Upper
+  Missouri Country,' 1876. Meek.</td></tr>
+</table>
+
+<h3>CHAPTER XVIII.</h3>
+
+<p class="subtitle">
+THE EOCENE PERIOD.
+</p>
+
+<p class="indent">
+Before commencing the study of the subdivisions of the Kainozoic
+series, there are some general considerations to be noted. In
+the first place, there is in the Old World a complete and entire
+physical break between the rocks of the Mesozoic and Kainozoic
+periods. In no instance in Europe are Tertiary strata to be found
+resting conformably upon any Secondary rock. The Chalk has invariably
+suffered much erosion and denudation before the lowest Tertiary
+strata were deposited upon it. This is shown by the fact that the
+<a name="page_285"><span class="page">Page 285</span></a>
+actually eroded surface of the Chalk can often
+be seen; or, failing this, that we can point to the presence of the
+chalk-flints in the Tertiary strata. This last, of course, affords
+unquestionable proof that the Chalk must have been subjected to
+enormous denudation prior to the formation of the Tertiary beds,
+all the chalk itself having been removed, and nothing left but the
+flints, while these are all rolled and rounded. In the continent
+of North America, on the other hand, the lowest Tertiary strata
+have been shown to graduate downwards conformably with the highest
+Cretaceous beds, it being a matter of difficulty to draw a precise
+line of demarcation between the two formations.
+</p>
+
+<p class="indent">
+In the second place, there is a marked break in the <i>life</i>
+of the Mesozoic and Kainozoic periods. With the exception of a
+few <i>Foraminifera</i>, and one <i>Brachiopod</i> (the latter
+doubtful), no Cretaceous species is known to have survived the
+Cretaceous period; while several characteristic <i>families</i>,
+such as the <i>Ammonitidœ, Belemnitidœ</i>, and
+<i>Hippuritidœ</i>, died out entirely with the close of the
+Cretaceous rocks. In the Tertiary rocks, on the other hand, not
+only are all the animals and plants more or less like existing
+types, but we meet with a constantly-increasing number of <i>living
+species</i> as we pass from the bottom of the Kainozoic series to
+the top. Upon this last fact is founded the modern classification
+of the Kainozoic rocks, propounded by Sil Charles Lyell.
+</p>
+
+<p class="indent">
+The absence in strata of Tertiary age of the chambered Cephalopods,
+the Belemnites, the <i>Hippurites</i>, the <i>Inocerami</i>, and
+the diversified types of Reptiles which form such conspicuous
+features in the Cretaceous fauna, render the palæontological
+break between the Chalk and the Eocene one far too serious to
+be overlooked. At the same time, it is to be remembered that
+the evidence afforded by the explorations carried out of late
+years as to the animal life of the deep sea, renders it certain
+that the extinction of marine forms of life at the close of the
+Cretaceous period was far less extensive than had been previously
+assumed. It is tolerably certain, in fact, that we may look upon
+some of the inhabitants of the depths of our existing oceans
+as the direct, if modified, descendants of animals which were
+in existence when the Chalk was deposited.
+</p>
+
+<p class="indent">
+It follows from the general want of conformity between the Cretaceous
+and Tertiary rocks, and still more from the great difference in
+life, that the Cretaceous and Tertiary periods are separated, in
+the Old World at any rate, by an enormous lapse of unrepresented
+time. How long this interval may have been, we have no means of
+judging exactly, but it very possibly was as long as the whole
+Kainozoic epoch itself. Some day we shall
+<a name="page_286"><span class="page">Page 286</span></a>
+doubtless find, at some part of the earth's surface, marine strata
+which were deposited during this period, and which will contain
+fossils intermediate in character between the organic remains
+which respectively characterise the Secondary and Tertiary periods.
+At present, we have only slight traces of such deposits&mdash;as,
+for instance, the Maestricht beds, the Faxöe Limestone, and
+the Pisolitic Limestone of France.
+</p>
+
+<p class="indent">
+CLASSIFICATION OF THE TERTIARY ROCKS.&mdash;The classification
+of the Tertiary rocks is a matter of unusual difficulty, in
+consequence of their occurring in disconnected basins, forming
+a series of detached areas, which hold no relations of
+superposition to one another. The order, therefore, of the
+Tertiaries in point of time, can only be determined by an appeal
+to fossils; and in such determination Sir Charles Lyell proposed
+to take as the basis of classification the <i>proportion of
+living or existing species of Mollusca which occurs in each
+stratum or group of strata</i>. Acting upon this principle,
+Sir Charles Lyell divides the Tertiary series into four
+groups:&mdash;
+</p>
+
+<p class="indent">
+I. The <i>Eocene</i> formation (Gr. <i>eos</i>, dawn; <i>kainos</i>,
+new), containing the smallest proportion of existing species, and
+being, therefore, the oldest division. In this classification,
+only the <i>Mollusca</i> are taken into account; and it was found
+that of these about three and a half per cent were identical
+with existing species.
+</p>
+
+<p class="indent">
+II. The <i>Miocene</i> formation (Gr. <i>meion</i>, less;
+<i>kainos</i>, new), with more recent species than the Eocene,
+but <i>less</i> than the succeeding formation, and less than
+one-half the total number in the formation. As before, only the
+<i>Mollusca</i> are taken into account, and about 17 per cent
+of these agree with existing species.
+</p>
+
+<p class="indent">
+III. The <i>Pliocene</i> formation (Gr. <i>pleion</i>, more;
+<i>kainos</i>, new), with generally <i>more</i> than half the
+species of shells identical with existing species&mdash;the
+proportion of these varying from 35 to 50 per cent in the lower
+beds of this division, up to 90 or 95 per cent in its higher
+portion.
+</p>
+
+<p class="indent">
+IV. The <i>Post-Tertiary Formations</i>, in which all <i>the
+shells belong to existing species</i>. This, in turn, is divided
+into two minor groups&mdash;the <i>Post-Pliocene</i> and <i>Recent
+Formations</i>. In the <i>Post-Pliocene</i> formations, while
+all the <i>Mollusca</i> belong to existing species, most of the
+<i>Mammals</i> belong to extinct species. In the Recent period,
+the quadrupeds, as well as the shells, belong to living species.
+</p>
+
+<p class="indent">
+The above, with some modifications, was the original classification
+proposed by Sir Charles Lyell for the Tertiary rocks, and now
+universally accepted. More recent researches, it is true, have
+somewhat altered the proportions of existing species
+<a name="page_287"><span class="page">Page 287</span></a>
+to extinct, as stated above. The general principle, however, of
+an increase in the number of living species, still holds good; and
+this is as yet the only satisfactory basis upon which it has been
+proposed to arrange the Tertiary deposits.
+</p>
+
+<p class="center">EOCENE FORMATION.</p>
+
+<p class="indent">
+The Eocene rocks are the lowest of the Tertiary series, and comprise
+all those Tertiary deposits in which there is only a small proportion
+of existing <i>Mollusca</i>&mdash;from three and a half to five per
+cent. The Eocene rocks occur in several basins in Britain, France,
+the Netherlands, and other parts of Europe, and in the United
+States. The subdivisions which have been established are extremely
+numerous, and it is often impossible to parallel those of one
+basin with those of another. It will be sufficient, therefore,
+to accept the division of the Eocene formation into three great
+groups&mdash;Lower, Middle, and Upper Eocene&mdash;and to consider
+some of the more important beds comprised under these heads in
+Europe and in North America.
+</p>
+
+<p class="indent">
+I. EOCENE OF BRITAIN. (1.) LOWER EOCENE.&mdash;The base of the Eocene
+series in Britain is constituted by about 90 feet of light-coloured,
+sometimes argillaceous sands (<i>Thanet Sands</i>), which are of
+marine origin. Above these, or forming the base of the formation
+where these are wanting, come mottled clays and sands with lignite
+(<i>Woolwich and Reading series</i>), which are estuarine or
+fluvio-marine in origin. The highest member of the Lower Eocene
+of Britain is the "London Clay," consisting of a great mass of
+dark-brown or blue clay, sometimes with sandy beds, or with layers
+of "septaria," the whole attaining a thickness of from 200 to as
+much as 500 feet. The London Clay is a purely marine deposit,
+containing many marine fossils, with the remains of terrestrial
+animals and plants; all of which indicate a high temperature of
+the sea and tropical or sub-tropical conditions of the land.
+</p>
+
+<p class="indent">
+(2.) MIDDLE EOCENE.&mdash;The inferior portion of the Middle
+Eocene of Britain consists of marine beds, chiefly consisting
+of sand, clays, and gravels, and attaining a very considerable
+thickness (<i>Bag-shot and Bracklesham beds</i>). The superior
+portion of the Middle Eocene of Britain, on the other hand,
+consists of deposits which are almost exclusively fresh-water
+or brackish-water in origin (<i>Headon and Osborne series</i>).
+</p>
+
+<p class="indent">
+The chief Continental formations of Middle Eocene age are the
+"Calcaire grossier" of the Paris basin, and the "Nummulitic
+Limestone" of the Alps.
+</p>
+
+<p class="indent">
+(3.) UPPER EOCENE.&mdash;If the Headon and Osborne beds of
+<a name="page_288"><span class="page">Page 288</span></a>
+the Isle of Wight be placed in the Middle Eocene, the only
+British representatives of the Upper Eocene are the <i>Bembridge
+beds</i>. These strata consist of limestones, clays, and marls,
+which have for the most part been deposited in fresh or brackish
+water.
+</p>
+
+<p class="indent">
+II. EOCENE BEDS OF THE PARIS BASIN.&mdash;The Eocene strata are
+very well developed in the neighbourhood of Paris, where they
+occupy a large area or basin scooped out of the Chalk. The beds
+of this area are partly marine, partly freshwater in origin; and
+the following table (after Sir Charles Lyell) shows their
+subdivisions and their parallelism with the English series:&mdash;
+</p>
+
+<p class="center">GENERAL TABLE OF FRENCH EOCENE STRATA.</p>
+
+<table border="0" width="100%">
+<tr><td colspan="5" class="center">UPPER EOCENE.</td></tr>
+<tr><td>&nbsp;</td>
+ <td colspan="2" class="center"><i>French Subdivisions.</i></td>
+ <td colspan="2" class="center"><i>English Equivalents.</i></td></tr>
+
+<tr><td valign="top">A.</td>
+ <td valign="top">1.</td>
+ <td valign="top">Gypseous series of Mont
+  Montmartre.</td>
+ <td valign="top">1.</td>
+ <td valign="top">Bembridge series.</td></tr>
+
+<tr><td valign="top">A.</td>
+ <td valign="top">2.</td>
+ <td valign="top">Calcaire silicieux, or Travertin
+  Inférieur.</td>
+ <td valign="top">2.</td>
+ <td valign="top">Osborne and Headon series.</td></tr>
+
+<tr><td valign="top">A.</td>
+ <td valign="top">3.</td>
+ <td valign="top">Grès de Beauchamp, or Sables Moyens.</td>
+ <td valign="top">3.</td>
+ <td valign="top">White sand and clay of Barton Cliff,
+  Hants.</td></tr>
+
+<tr><td colspan="5" class="center">MIDDLE EOCENE.</td></tr>
+
+<tr><td valign="top">B.</td>
+ <td valign="top">1.</td>
+ <td valign="top">Calcaire Grossier.</td>
+ <td valign="top">1.</td>
+ <td valign="top">Bagshot and Bracklesham beds.</td></tr>
+
+<tr><td valign="top">B.</td>
+ <td valign="top">2.</td>
+ <td valign="top">Soissonnais Sands, or Lits Coquilliers.</td>
+ <td valign="top">2.</td>
+ <td valign="top">Wanting.</td></tr>
+
+<tr><td colspan="5" class="center">LOWER EOCENE.</td></tr>
+
+<tr><td valign="top">C.</td>
+ <td valign="top">1.</td>
+ <td valign="top">Argile de Londres at base of Hill of Cassel,
+  near Dunkirk.</td>
+ <td valign="top">1.</td>
+ <td valign="top">London clay.</td></tr>
+
+<tr><td valign="top">C.</td>
+ <td valign="top">2.</td>
+ <td valign="top">Argile plastique and lignite.</td>
+ <td valign="top">2.</td>
+ <td valign="top">Plastic clay and sand with lignite (Woolwich
+  and Reading series).</td></tr>
+
+<tr><td valign="top">C.</td>
+ <td valign="top">3.</td>
+ <td valign="top">Stables de Bracheux.</td>
+ <td valign="top">3.</td>
+ <td valign="top">Thanet sands.</td></tr>
+
+</table>
+
+<p class="indent">
+III. EOCENE STRATA OF THE UNITED STATES.&mdash;The lowest member of
+the Eocene deposits of North America is the so-called "<i>Lignitic
+Formation</i>," which is largely developed in Mississippi, Tennessee,
+Arkansas, Wyoming, Utah, Colorado, and California, and sometimes
+attains a thickness of several thousand feet. Stratigraphically,
+this formation exhibits the interesting point that it graduates
+downwards insensibly and conformably into the Cretaceous, whilst
+it is succeeded <i>uncomformably</i> by strata of Middle Eocene
+age. Lithologically, the series consists principally of sands
+and clays, with beds of lignite and coal, and its organic remains
+show that it is principally of fresh-water origin with a partial
+intermixture of marine beds.
+<a name="page_289"><span class="page">Page 289</span></a>
+These marine
+strata of the "Lignitic formation" are of special interest, as
+showing such a commingling of Cretaceous and Tertiary types of
+life, that it is impossible to draw any rigid line in this region
+between the Mesozoic and Kainozoic systems. Thus the marine beds
+of the Lignitic series contain such characteristic Cretaceous
+forms as <i>Inoceramus</i> and <i>Ammonites</i>, along with a great
+number of Univalves of a distinctly Tertiary type (Cones, Cowries,
+&amp;c.) Upon the whole, therefore, we must regard this series of
+deposits as affording a kind of transition between the Cretaceous
+and the Eocene, holding in some respects a position which may be
+compared with that held by the Purbeck beds in Britain as regards
+the Jurassic and Cretaceous.
+</p>
+
+<p class="indent">
+The Middle Eocene of the United States is represented by the
+<i>Claiborne</i> and <i>Jackson</i> beds. The <i>Claiborne series</i>
+is extensively developed at Claiborne, Alabama, and consists of
+sands, clays, lignites, marls, and impure limestones, containing
+marine fossils along with numerous plant-remains. The <i>Jackson
+series</i> is represented by lignitic clays and marls which occur
+at Jackson, Mississippi. Amongst the more remarkable fossils of
+this series are the teeth and bones of Cetaceans of the genus
+<i>Zeuglodon</i>.
+</p>
+
+<p class="indent">
+Strata of Upper Eocene age occur in North America at Vicksburg,
+Mississippi, and are known as the <i>Vicksburg series</i>. They
+consist of lignites, clays, marls, and limestones. Freshwater
+deposits of Eocene age are also largely developed in parts of
+the Rocky Mountain region. The most remarkable fossils of these
+beds are Mammals, of which a large number of species have been
+already determined.
+</p>
+
+<p class="center">LIFE OF THE EOCENE PERIOD.</p>
+
+<p class="indent">
+The fossils of the Eocene deposits are so numerous that nothing
+more can be attempted here than to give a brief and general sketch
+of the life of the period, special attention being directed to some
+of the more prominent and interesting types, amongst which&mdash;as
+throughout the Tertiary series&mdash;the Mammals hold the first place.
+It is not uncommon, indeed, to speak of the Tertiary period as a
+whole under the name of the "Age of Mammals," a title at least
+as well deserved as that of "Age of Reptiles" applied to the
+Mesozoic, or "Age of Molluscs" applied to the Palæozoic epoch.
+</p>
+
+<p class="indent">
+As regards the <i>plants</i> of the Eocene, the chief point to
+be noticed is, that the conditions which had already set in with
+the commencement of the Upper Cretaceous, are here continued,
+<a name="page_290"><span class="page">Page 290</span></a>
+and still further enforced. The
+<i>Cycads</i> of the Secondary period, if they have not totally
+disappeared, are exceedingly rare; and the <i>Conifers</i>,
+losing the predominance which they enjoyed in the Mesozoic, are
+now relegated to a subordinate though well-defined place in the
+terrestrial vegetation. The great majority of the Eocene plants
+are referable to the groups of the Angiospermous Exogens and the
+Monocotyledons; and the vegetation of the period, upon the whole,
+approximates closely to that now existing upon the earth. The
+plants of the European Eocene are, however, in the main most
+closely allied to forms which are now characteristic of tropical
+or sub-tropical regions. Thus, in the London Clay are found
+numerous fruits of Palms (<i>Napdites</i>, fig. 213), along with
+various other plants,
+
+<span style="float: left; margin: 4px; width: 176px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig213.jpg" width="176" height="222" alt="Fig. 213" />
+<br />
+Fig. 213.&mdash;<i>Napadites ellipticus</i>, the fruit of a fossil
+Palm. London Clay, Isle of Sheppey.
+</span>
+
+most of which indicate a warm climate as prevailing in the south
+of England at the commencement of the Eocene period. In the Eocene
+strata of North America occur numerous plants belonging to existing
+types&mdash;such as Palms, Conifers, the Magnolia, Cinnamon, Fig.
+Dog-wood, Maple, Hickory, Poplar, Plane, &amp;c. Taken as a whole,
+the Eocene flora of North America is nearly related to that of
+the Miocene strata of Europe, as well as to that now existing
+in the American area. We conclude, therefore, that "the forests
+of the American Eocene resembled those of the European Miocene,
+and even of modern America" (Dana).
+</p>
+
+<p class="indent">
+As regards the <i>animals</i> of the Eocene period, the
+<i>Protozoans</i> are represented by numerous <i>Foraminifera</i>,
+which reach here their maximum of development, both as regards
+the size of individuals and the number of generic types. Many
+of the Eocene Foraminifers are of small size; but even these not
+uncommonly form whole rock-masses. Thus, the so-called "Miliolite
+Limestone" of the Paris basin, largely used as a building-stone,
+is almost wholly composed of the shells of a small species of
+<i>Miliola</i>. The most remarkable, however, of the many members
+of this group of animals which flourished in Eocene times, are the
+"Nummulites" (<i>Nummulina</i>), so called from their resemblance
+in shape to coins (Lat. <i>nummus</i>, a coin). The Nummulites are
+amongst the largest of all known <i>Foraminifera</i>, sometimes
+attaining a size of three inches in circumference; and their
+internal structure is very complex (fig. 214).
+<a name="page_291"><span class="page">Page 291</span></a>
+Many species are
+known, and they are particularly characteristic of the Middle and
+Upper of these periods&mdash;their place being sometimes taken
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 441px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig214.jpg" width="441" height="176" alt="Fig. 214" />
+<br />
+Fig. 214.&mdash;<i>Nummulina lœvigata</i>. Middle Eocene.
+</span>
+</span>
+
+by <i>Orbitoides</i>, a form very similar to the Nummulite in
+external appearance, but differing in its internal details. In
+the Middle Eocene, the remains of Nummulites are found in vast
+numbers in a very widely-spread and easily-recognised formation
+known as the "Nummulitic Limestone" (fig. 10). According to Sir
+Charles Lyell, "the Nummulitic Limestone of the Swiss Alps rises
+to more than 10,000 feet above the level of the sea, and attains
+here and in other mountain-chains a thickness of several thousand
+feet. It may be said to play a far more conspicuous part than
+any other Tertiary group in the solid framework of the earth's
+crust, whether in Europe, Asia, or Africa. It occurs in Algeria
+and Morocco, and has been traced from Egypt, where it was largely
+quarried of old for the building of the Pyramids, into Asia Minor,
+and across Persia by Bagdad to the mouths of the Indus. It has
+been observed not only in Cutch, but in the mountain-ranges which
+separate Scinde from Persia, and which form the passes leading
+to Cabul; and it has been followed still further eastward into
+India, as far as Eastern Bengal and the frontiers of China." The
+shells of Nummulites have been found at an elevation of 16,500
+feet above the level of the sea in Western Thibet; and the
+distinguished and philosophical geologist just quoted, further
+remarks, that "when we have once arrived at the conviction that
+the Nummulitic formation occupies a middle and upper place in the
+Eocene series, we are struck with the comparatively modern date to
+which some of the greatest revolutions in the physical geography
+of Europe, Asia, and Northern Africa must be referred. All the
+mountain-chains&mdash;such as the Alps, Pyrenees, Carpathians, and
+Himalayas&mdash;into the composition of whose central and loftiest
+parts the Nummulitic
+<a name="page_292"><span class="page">Page 292</span></a>
+strata enter bodily, could have had no existence till after the
+Middle Eocene period. During that period, the sea prevailed where
+these chains now rise; for Nummulites and their accompanying
+Testacea were unquestionably inhabitants of salt water."
+</p>
+
+<p class="indent">
+The <i>Cœlenterates</i> of the Eocene are represented
+principally by <i>Corals</i>, mostly of types identical with or
+nearly allied to those now in existence. Perhaps the most
+characteristic group of these is that of the <i>Turbinolidœ</i>,
+comprising a number of simple "cup-corals," which probably lived in
+moderately deep water. One of the forms belonging to this family is
+here figured (fig. 215). Besides true Corals, the Eocene deposits have
+
+<span style="float: left; margin: 4px; width: 156px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig215.jpg" width="156" height="490" alt="Fig. 215" />
+<br />
+Fig. 215.&mdash;<i>Turbinolia sulcata</i>, viewed from one side,
+and from above. Eocene.
+</span>
+
+yielded the remains of the "Sea-pens" (<i>Pennatulidœ</i>) and
+the branched skeletons of the "Sea-shrubs" (<i>Gorgontidœ</i>).
+</p>
+
+<p class="indent">
+The <i>Echinoderms</i> are represented principally by Sea-urchins,
+and demand nothing more than mention. It is to be observed, however,
+that the great group of the Sea-lilies (<i>Crinoids</i>) is now
+verging on extinction, and is but very feebly represented.
+</p>
+
+<p class="indent">
+Amongst the <i>Mollusca</i>, the <i>Polyzoans</i> and
+<i>Brachiopods</i> also require no special mention, beyond the
+fact that the latter are greatly reduced in numbers, and belong
+principally to the existing genera <i>Terebratula</i> and
+<i>Rhynchonella</i>. The Bivalves (<i>Lamellibranchs</i>) and
+the Univalves (<i>Gasteropods</i>) are exceedingly numerous, and
+almost all the principal existing genera are now represented;
+though less than five percent of the Eocene <i>species</i> are
+identical with those now living. It is difficult to make any
+selection from the many Bivalves which are known in deposits of
+this age; but species of <i>Cardita, Crassatella, Leda, Cyrena,
+Mactra, Cardium, Psammobia</i>, &amp;c., may be mentioned as very
+characteristic. The <i>Caradita planicosta</i> here figured (fig.
+216) is not only very abundant in the Middle Eocene, but is very
+widely distributed, ranging from Europe to the Pacific coast of
+North America. The <i>Univalves</i> of the Eocene are extremely
+numerous, and generally beautifully preserved. The majority of them
+belong to that great section of the <i>Gasteropods</i> in which the
+mouth of the shell is notched or produced into
+<a name="page_293"><span class="page">Page 293</span></a>
+a canal (when the
+shell is said to be "siphonostomatous")&mdash;this section including
+the carnivorous and most highly-organized groups of the class. Not
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 530px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig216.jpg" width="530" height="209" alt="Fig. 216" />
+<br />
+Fig. 216.&mdash;<i>Cardita planicosta</i>. Middle Eocene.
+</span>
+</span>
+
+only is this the case, but a large number of the Eocene Univalves
+belong to types which now attain their maximum of development in the
+warmer regions of the globe. Thus we find numerous species of Cones
+(<i>Conus</i>), Volutes (<i>Voluta</i>), Cowries (<i>Cyprœa</i>,
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 281px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig217.jpg" width="281" height="212" alt="Fig. 217" />
+<br />
+Fig. 217.&mdash;<i>Typhis tubifer</i>, a "siphonostomatous" Univalve.
+Eocene.
+</span>
+
+<span style="width: 156px; vertical-align:bottom; text-align: justify;
+  margin: 4px;">
+<img src="images/fig218.jpg" width="156" height="240" alt="Fig. 218" />
+<br />
+Fig. 218.&mdash;Cyprœa elegans. Eocene.
+</span>
+
+</span>
+
+fig. 218), Olives and Rice-shells (<i>Oliva</i>), Mitre-shells
+(<i>Mitra</i>), Trumpet-shells (<i>Triton</i>), Auger-shells
+(<i>Terebra</i>), and Fig-shells (<i>Pyrula</i>). Along with these
+are many forms of <i>Pleurotoma, Rostellaria</i>, Spindle-shells
+(<i>Fusus</i>), Dog-whelks (<i>Nassa</i>), <i>Murices</i>, and
+many round-mouthed ("holostomatous") species, belonging to such
+genera as <i>Turritella, Nerita, Natica, Scalaria</i>, &amp;c.
+The genus <i>Cerithium</i> (fig. 219), most of the living forms
+of which are found in warm regions, inhabiting fresh or brackish
+waters, undergoes a vast development in the Eocene period, where
+<a name="page_294"><span class="page">Page 294</span></a>
+it is represented by an immense number of specific forms, some
+of which attain very large dimensions. In the Eocene strata of
+
+<span style="float: left; margin: 4px; width: 138px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig219.jpg" width="138" height="266" alt="Fig. 219" />
+<br />
+Fig. 219.&mdash;<i>Cerithium hexagonum</i>. Eocene.
+</span>
+
+the Paris basin alone, nearly one hundred and fifty species of
+this genus have been detected. The more strictly fresh-water
+deposits of the Eocene period have also yielded numerous remains
+of Univalves such as are now proper to rivers and lakes, together
+with the shells of true Land-snails. Amongst these may be mentioned
+numerous species of <i>Limnœa</i> (fig. 220), <i>Physa</i>
+(fig. 221), <i>Melania, Paludina, Planorbis, Helix, Bulimus</i>,
+and <i>Cyclostoma</i> (fig. 222).
+</p>
+
+<p class="indent">
+With regard to the <i>Cephalopods</i>, the chief point to be
+noticed is, that all the beautiful and complex forms which peculiarly
+characterised the Cretaceous period have here disappeared. We no
+longer meet with a single example of the Turrilite, the Baculite,
+the Hamite, the Scaphite, or the Ammonite. The only exception
+to this statement is the occurrence of one species of Ammonite
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 92px; vertical-align:bottom; text-align: center;
+  margin: 12px;">
+<img src="images/fig220.jpg" width="92" height="186" alt="Fig. 220" />
+<br />
+Fig. 220.&mdash;<i>Limnœa pyramidalis</i>. Eocene.
+</span>
+
+<span style="width: 64px; vertical-align:bottom; text-align: center;
+  margin: 12px;">
+<img src="images/fig221.jpg" width="64" height="194" alt="Fig. 221" />
+<br />
+Fig. 221.&mdash;<i>Physa columnaris</i>. Eocene.
+</span>
+
+<span style="width: 95px; vertical-align:bottom; text-align: center;
+  margin: 12px;">
+<img src="images/fig222.jpg" width="95" height="156" alt="Fig. 222" />
+<br />
+Fig. 222.&mdash;<i>Cyclostoma Arnoudii</i>. Eocene.
+</span>
+
+</span>
+
+in the so-called "Lignitic Formation" of North America; but the
+beds containing this may possibly be rather referable to the
+Cretaceous&mdash;and this exception does not affect the fact
+that the <i>Ammonitidœ</i>, as a family, had become
+extinct before the Eocene strata were deposited. The ancient
+genus <i>Nautilus</i> still survives, the sole representative
+of the once mighty order of the Tetrabranchiate Cephalopods.
+In the order of the <i>Dibranchiates</i>, we have a like
+phenomenon to observe in the total extinction of the great
+family of the "Belemnites." No form referable to this group
+<a name="page_295"><span class="page">Page 295</span></a>
+has hitherto been found in any Tertiary stratum; but the
+internal skeletons of Cuttle-fishes (such as <i>Belosepia</i>)
+are not unknown.
+</p>
+
+<p class="indent">
+Remains of <i>Fishes</i> are very abundant in strata of Eocene
+age, especially in certain localities. The most famous depot for
+the fossil fishes of this period is the limestone of Monte Bolca,
+near Verona, which is interstratified with beds of volcanic ashes,
+the whole being referable to the Middle Eocene. The fishes here
+seem to have been suddenly destroyed by a volcanic eruption,
+and are found in vast numbers. Agassiz has described over one
+hundred and thirty species of Fishes from this locality, belonging
+to seventy-seven genera. All the <i>species</i> are extinct; but
+about one-half of the <i>genera</i> are represented by living
+forms. The great majority of the Eocene Fishes belong to the
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 500px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig223.jpg" width="500" height="291" alt="Fig. 223" />
+<br />
+Fig. 223.&mdash;<i>Rhombus minimus</i>, a small fossil Turbot from
+the Eocene Tertiary, Monte Bolca.
+</span>
+</span>
+
+order of the "Bony Fishes" (<i>Teleosteans</i>), so that in the
+main the forms of Fishes characterising the Eocene are similar
+to those which predominate in existing seas. In addition to the
+above, a few <i>Ganoids</i> and a large number of <i>Placoids</i>
+are known to occur in the Eocene rocks. Amongst the latter are
+found numerous teeth of true Sharks, such as <i>Otodus</i> (fig.
+224) and <i>Carcharodon</i>. The pointed and serrated teeth of the
+latter sometimes attain a length of over half a foot, indicating
+that these predaceous fishes attained gigantic dimensions; and it
+is interesting to note that teeth, in external appearance very
+similar to those of the early Tertiary genus <i>Carcharodon</i>,
+have been dredged from great depths during the recent expedition
+of the Challenger. There also occur not uncommonly the flattened
+<a name="page_296"><span class="page">Page 296</span></a>
+teeth of Rays (fig. 225), consisting of flat bony pieces placed
+close together, and forming "a kind of mosaic pavement on both
+the upper and lower jaws" (Owen).
+</p>
+
+<p class="indent">
+In the class of the <i>Reptiles</i>, the disappearance of the
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 130px; vertical-align:bottom;
+  text-align: center; margin: 4px;">
+<img src="images/fig224.jpg" width="130" height="168" alt="Fig. 224" />
+<br />
+Fig. 224.&mdash;Tooth of <i>Otodus obliquus</i>. Eocene.
+</span>
+
+<span style="width: 240px; vertical-align:bottom;
+  text-align: center; margin: 4px;">
+<img src="images/fig225.jpg" width="240" height="153" alt="Fig. 225" />
+<br />
+Fig. 225.&mdash;Flattened dental plates of a Ray (<i>Myliobatis
+Edwardsii</i>). Eocene.
+</span>
+
+</span>
+
+characteristic Mesozoic types is as marked a phenomenon as the
+introduction of new forms. The Ichthyosaurs, the Plesiosaurs,
+the Pterosaurs, and the Mosasaurs of the Mesozoic, find no
+representatives in the Eocene Tertiary; and the same is true
+of the Deinosaurs, if we except a few remains from the
+doubtfully-situated "Lignitic formation" of the United States,
+On the other hand, all the modern orders of Reptiles are known to
+have existed during the Eocene period. The <i>Chelonians</i> are
+represented by true marine Turtles, by "Terrapins"
+(<i>Emydidœ</i>), and by "Soft Tortoises"
+(<i>Trionycidœ</i>). The order of the Snakes and Serpents
+(<i>Ophidia</i>) makes its appearance here, for the first time
+under several forms&mdash;all of which, however, are referable to
+the non-venomous group of the "Constricting Serpents"
+(<i>Boidœ</i>). The oldest of these is the <i>Palœophis
+toliapicus</i> of the London Clay of Sheppey, first made known to
+science by the researches of Professor Owen. The nearly-allied
+<i>Palœophis typhœus</i> of the Eocene beds of
+Bracklesham appears to have been a Boa-constrictor-like Snake of
+about twenty feet in length. Similar Python-like Snakes
+(<i>Palœophis, Dinophis</i>, &amp;c.) have been described
+from the Eocene deposits of the United States. True Lizards
+(<i>Lacertilians</i>) are found in some abundance in the Eocene
+deposits,&mdash;some being small terrestrial forms, like the
+common European lizards of the present day; whilst others equal or
+exceed the living Monitors in size. Lastly, the modern order of
+the <i>Crocodilia</i> is largely represented in Eocene times, by
+species belonging to all the existing genera, together with
+others referable to extinct types. As pointed out by Owen, it
+is an interesting fact that in the Eocene rocks of the south-west
+<a name="page_297"><span class="page">Page 297</span></a>
+of England, there occur fossil remains of all the three living
+types of Crocodilians&mdash;namely, the Gavials, the true
+Crocodiles, and the Alligators (fig. 226)&mdash;though at the
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 502px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig226.jpg" width="502" height="263" alt="Fig. 226" />
+<br />
+Fig. 226.&mdash;Upper jaw of Alligator. Eocene Tertiary, Isle of
+Wight.
+</span>
+</span>
+
+present day these forms are all geographically restricted in
+their range, and are never associated together.
+</p>
+
+<p class="indent">
+Almost all the existing orders of <i>Birds</i>, if not all, are
+represented in the Eocene deposits by remains often very closely
+allied to existing types. Thus, amongst the Swimming Birds
+(<i>Natatores</i>) we find examples of forms allied to the living
+Pelicans and Mergansers; amongst the Waders (<i>Grallatores</i>)
+we have birds resembling the Ibis (the <i>Numenius gypsorum</i> of
+the Paris basin); amongst the Running Birds (<i>Cursores</i>) we
+meet with the great <i>Gastornis Parisiensis</i>, which equalled
+the African Ostrich in height, and the still more gigantic
+<i>Dasornis Londinensis</i>; remains of a Partridge represent
+the Scratching Birds (<i>Rasores</i>); the American Eocene has
+yielded the bones of one of the Climbing Birds (<i>Scansores</i>),
+apparently referable to the Woodpeckers; the <i>Protornis
+Glarisiensis</i> of the Eocene Schists of Glaris is the oldest
+known example of the Perching Birds (<i>Insessores</i>); and
+the Birds of Prey (<i>Raptores</i>) are represented by Vultures,
+Owls, and Hawks. The toothed Birds of the Upper Cretaceous are no
+longer known to exist; but Professor Owen has recently described
+from the London Clay the skull of a very remarkable Bird, in
+which there is, at any rate, an approximation to the structure of
+<i>Ichthyornis</i> and <i>Hesperornis</i>. The bird in question
+has been named the <i>Odontopteryx totiapicus</i>, its generic
+title being derived from the very remarkable characters of its
+jaws. In this singular form (fig. 227) the margins of both jaws
+<a name="page_298"><span class="page">Page 298</span></a>
+are furnished with tooth-like denticulations, which differ from
+true teeth in being actually portions of the bony substance of
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 559px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig227.jpg" width="559" height="202" alt="Fig. 227" />
+<br />
+Fig. 227.&mdash;Skull of <i>Odontopteryx toliapicus</i> restored.
+(After Owen.)
+</span>
+</span>
+
+the jaw itself, with which they are continuous, and which were
+probably encased by extensions of the horny sheath of the bill.
+These tooth-like processes are of two sizes, the larger ones
+being comparable to canines; and they are all directed forwards,
+and have a triangular or compressed conical form. From a careful
+consideration of all the discovered remains of this bird, Professor
+Owen concludes that "<i>Odontopteryx</i> was a warm-blooded
+feathered biped, with wings; and further, that it was web-footed
+and a fish-eater, and that in the catching of its slippery prey
+it was assisted by this Pterosauroid armature of its jaws." Upon
+the whole, <i>Odontopteryx</i> would appear to be most nearly
+related to the family of the Geese (<i>Anserinœ</i>) or Ducks
+(<i>Anatidœ</i>); but the extension of the bony substance of
+the jaws into tooth-like processes is an entirely unique character,
+in which it stands quite alone.
+</p>
+
+<p class="indent">
+The known <i>Mammals</i> of the Mesozoic period, as we have seen,
+are all of small size; and with one not unequivocal exception,
+they appear to be referable to the order of the Pouched Quadrupeds
+(<i>Marsupials</i>), almost the lowest group of the whole class
+of the Mammalia. In the Eocene rocks, on the other hand, numerous
+remains of Quadrupeds have been brought to light, representing
+most of the great Mammalian orders now in existence upon the
+earth, and in many cases indicating animals of very considerable
+dimensions. We are, in fact, in a position to assert that the
+majority of the great groups of Quadrupeds with which we are
+familiar at the present day were already in existence in the
+Eocene period, and that their ancient root-stocks were even in
+this early time separated by most of the fundamental differences
+of structure
+<a name="page_299"><span class="page">Page 299</span></a>
+which distinguish their living representatives. At the same time,
+there are some amongst the Eocene quadrupeds which have a
+"generalised" character, and which may be regarded as structural
+types standing midway between groups now sharply separated from
+one another.
+</p>
+
+<p class="indent">
+The order of the <i>Marsupials</i>&mdash;including the existing
+Kangaroos, Wombats, Opossums, Phalangers, &amp;c.&mdash;is poorly
+represented in deposits of Eocene age. The most celebrated
+example of this group is the <i>Didelphys gypsorum</i> of the
+Gypseous beds of Montmartre, near Paris, an Opossum very nearly
+allied to the living Opossums of North and South America.
+</p>
+
+<p class="indent">
+No member of the <i>Edenates</i> (Sloths, Ant-eaters, and Armadillos)
+has hitherto been detected in any Eocene deposit. The aquatic
+order of the <i>Sirenians</i> (Dugongs and Manatees), with their
+fish-like bodies and tails, paddle-shaped forelimbs, and wholly
+deficient hind-limbs, are represented in strata of this age by
+remains of the ancient "Sea-Cows," to which the name of
+<i>Halitherium</i> has been applied. Nearly allied to the preceding
+is the likewise aquatic order of the Whales and Dolphins
+(<i>Cetaceans</i>), in which the body is also fish-like, the
+hind-limbs are wanting, the fore-limbs are converted into powerful
+"flippers" or swimming-paddles, and the terminal extremity of
+the body is furnished with a horizontal, tail-fin. Many existing
+Cetaceans (such as the Whalebone Whales) have no true teeth;
+but others (Dolphins, Porpoises, Sperm Whales) possess simple
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 510px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig228.jpg" width="510" height="248" alt="Fig. 228" />
+<br />
+Fig. 228.&mdash;<i>Zeuglodon cetoides</i>. A, Molar
+tooth of the natural size; B, Vertebra, reduced in size. From the
+Middle Eocene of the United States. (After Lyell.)
+</span>
+</span>
+
+conical teeth. In strata of Eocene age, however, we find a singular
+group of Whales, constituting the genus <i>Zeuglodon</i> (fig. 228),
+<a name="page_300"><span class="page">Page 300</span></a>
+in which the teeth differed from those of all
+existing forms in being of two kinds,&mdash;the front ones being
+conical incisors, whilst the back teeth or molars have serrated
+triangular crowns, and are inserted in the jaw by two roots. Each
+molar (fig. 228, A) looks as if it were composed of two separate
+teeth united on one side by their crowns; and it is this peculiarity
+which is expressed by the generic name (Gr. <i>zeugle</i>, a yoke;
+<i>odous</i>, tooth). The best-known species of the genus is
+the <i>Zeuglodon cetoides</i> of Owen, which attained a length
+of seventy feet. Remains of these gigantic Whales are very common
+in the "Jackson Beds" of the Southern United States. So common
+are they that, according to Dana, "the large vertebræ, some of
+them a foot and a half long and a foot in diameter, were formerly
+so abundant over the country, in Alabama, that they were used
+for making walls, or were burned to rid the fields of them."
+</p>
+
+<p class="indent">
+The great and important order of the Hoofed Quadrupeds
+(<i>Ungulata</i>) is represented in the Eocene by examples of both
+of its two principal sections&mdash;namely, those with an uneven
+number of toes (one or three) on the foot (<i>Perissodactyle
+Ungulates</i>), and those with an even number of toes (two or four)
+to each foot (<i>Artiodactyle Ungulates</i>). Amongst the Odd-toed
+Ungulates, the living family of the Tapirs (<i>Tapirdœ</i>) is
+represented by the genus <i>Coryphodon</i> of Owen. Nearly related
+to the preceding are the species of <i>Palœotherium</i>,
+which have a historical interest as being amongst the first of the
+Tertiary Mammals investigated by the illustrious Cuvier. Several
+species of <i>Palœothere</i> are known, varying greatly in
+size, the smallest being little bigger than a hare, whilst the
+largest must have equalled a good-sized horse in its dimensions. The
+species of <i>Palœotherium</i> appear to have agreed with the
+existing Tapirs in possessing a lengthened and flexible nose, which
+formed a short proboscis or trunk (fig. 229), suitable as an
+instrument for stripping off the foliage of trees&mdash;the characters
+of the molar teeth showing them to have been strictly herbivorous
+in their habits. They differ, however, from the Tapirs, amongst
+other characters, in the fact that both the fore and the hind feet
+possessed three toes each; whereas in the latter there are four
+toes on each fore-foot, and the hind-feet alone are three-toed. The
+remains of <i>Palœotheria</i> have been found in such abundance
+in certain localities as to show that these animals roamed in great
+herds over the fertile plains of France and the south of England
+during the later portion of the Eocene period. The accompanying
+illustration (fig. 229) represents the notion which the great
+Cuvier was induced by
+<a name="page_301"><span class="page">Page 301</span></a>
+his researches to form as to the outward
+appearance of <i>Palœotherium magnum</i>. Recent discoveries,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 487px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig229.jpg" width="487" height="294" alt="Fig. 229" />
+<br />
+Fig. 229.&mdash;Outline of <i>Palœotherium magnum</i>,
+restored. Upper Eocene, Europe. (After Cuvier.)
+</span>
+</span>
+
+however, have rendered it probable that this restoration is in some
+important respects inaccurate. Instead of being bulky, massive,
+and more or less resembling the living Tapirs in form, it would
+rather appear that <i>Palœotherium magnum</i> was in reality a
+slender, graceful, and long-necked animal, more closely resembling
+in general figure a Llama, or certain of the Antelopes.
+</p>
+
+<p class="indent">
+The singular genus <i>Anchitherium</i> forms a kind of transition
+between the <i>Palœotheria</i> and the true Horses
+(<i>Equidœ</i>). The Horse (fig. 230, D) possesses but one
+fully-developed toe to each foot, this being terminated by a single
+broad hoof, and representing the <i>middle</i> toe&mdash;the
+<i>third</i> of the typical five-fingered or five-toed limb of
+Quadrupeds in general. In addition, however, to this fully-developed
+toe, each foot in the horse carries two rudimentary toes which are
+concealed beneath the skin, and are known as the "splint-bones."
+These are respectively the <i>second</i> and <i>fourth</i> toes,
+in an aborted condition; and the first and fifth toes are wholly
+wanting. In <i>Hipparion</i> (fig. 230, C), the foot is essentially
+like that of the modern Horses, except that the second and fourth
+toes no longer are mere "splint-bones," hidden beneath the skin;
+but have now little hoofs, and hang freely, but uselessly, by the
+side of the great middle toe, not being sufficiently developed to
+reach the ground. In <i>Anchitherium</i>, again (fig. 230, B),
+the foot is three-toed, like that of <i>Hipparion</i>; but the
+two lateral toes (the second and fourth) are so far
+<a name="page_302"><span class="page">Page 302</span></a>
+developed that they now reach the ground.
+The <i>first</i> digit (thumb or great toe) is still wanting;
+as also is the <i>fifth</i> digit (little finger or little toe).
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 518px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig230.jpg" width="518" height="283" alt="Fig. 230" />
+<br />
+Fig. 230.&mdash;Skeleton of the foot in various forms belonging to
+the family of the <i>Equidœ</i>. A, Foot of <i>Orohippus</i>,
+Eocene; B, Foot of <i>Anchitherium</i>, Upper Eocene and Lower
+Miocene; C, Foot of <i>Hipparion</i>, Upper Miocene and Pliocene:
+D, Foot of Horse (<i>Equus</i>), Pliocene and Recent. The figures
+indicate the numbers of the digits in the typical five-fingered
+hand of Mammals. (After Marsh.)
+</span>
+</span>
+
+Lastly, the Eocene rocks have yielded in North America the remains
+of a small Equine quadruped, to which Marsh has given the name of
+<i>Orohippus</i>. In this singular form&mdash;which was not larger
+than a fox&mdash;the foot (fig. 230, A) carries <i>four</i> toes,
+all of which are hoofed and touch the ground, but of which the
+<i>third</i> toe is still the largest. The <i>first</i> toe
+(thumb or great toe) is still wanting; but in this ancient
+representative of the Horses, the <i>fifth</i> or "little" toe
+appears for the first time. As all the above-mentioned forms
+succeed one another in point of time, it may be regarded as
+probable that we shall yet be able to point, with some certainty,
+to some still older example of the <i>Equidœ</i>, in which
+the first digit is developed, and the foot assumes its typical
+five-fingered condition.
+</p>
+
+<p class="indent">
+Passing on to the Even-toed or <i>Artiodactyle Ungulates</i>, no
+representative of the <i>Hippotamus</i> seems yet to have existed,
+but there are several forms (<i>Chœropotamus, Hyopotamus</i>,
+&amp;c.) more or less closely allied to the Pigs (<i>Suida</i>); and
+the singular group of the <i>Anoplotheridœ</i> may be regarded
+as forming a kind of transition between the Swine and the Ruminants.
+The <i>Anoplotheria</i> (fig. 231) were slender in form, the
+largest not exceeding a donkey in size, with long tails, and
+having the feet terminated by two hoofed toes each, sometimes
+with a pair of small accessory hoofs as well. The teeth exhibit
+<a name="page_303"><span class="page">Page 303</span></a>
+the peculiarity that they are arranged in a continuous series,
+without any gap or interval between the molars and the canines;
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 495px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig231.jpg" width="495" height="240" alt="Fig. 231" />
+<br />
+Fig. 231.&mdash;<i>Anoplotherium commune</i>. Eocene Tertiary,
+France. (After Cuvier.)
+</span>
+</span>
+
+and the back teeth, like those of all the Ungulates, are adapted
+for grinding vegetable food, their crowns resembling in form
+those of the true Ruminants. The genera <i>Dichobune</i> and
+<i>Xiphodon</i>, of the Middle and Upper Eocene, are closely related
+to <i>Anoplotherium</i>, but are more slender and deer-like in
+form. No example of the great Ruminant group of the Ungulate
+Quadrupeds has as yet been detected in deposits of Eocene age.
+</p>
+
+<p class="indent">
+Whilst true Ruminants appear to be unknown, the Eocene strata
+of North America have yielded to the researches of Professor
+Marsh examples of an extraordinary group (<i>Dinocerata</i>),
+which may be considered as in some respects intermediate between
+the Ungulates and the Proboscideans. In <i>Dinoceras</i> itself
+(fig. 232) we have a large animal, equal in dimensions to the
+living Elephants, which it further resembles in the structure
+of the massive limbs, except that there are only four toes to
+each foot. The upper jaw was devoid of front teeth, but there
+were two very large canine teeth, in the form of tusks directed
+perpendicularly downwards; and there was also a series of six small
+molars on each. Each upper jaw-bone carried a bony projection, which
+was probably of the nature of a "horn-core," and was originally
+sheathed in horn. Two similar, but smaller, horn-cores are carried
+on the nasal bones; and two much larger projections, also probably
+of the nature of horn-cores, were carried upon the forehead. We
+may thus infer that <i>Dinoceras</i> possessed three pairs of
+horns, all of which resembled the horns of the Sheep and Oxen
+in consisting of a central bony "core," surrounded by a horny
+<a name="page_304"><span class="page">Page 304</span></a>
+sheath. The nose was not prolonged into a proboscis or "trunk,"
+as in the existing Elephants; and the tail was short and slender.
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 538px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig232.jpg" width="538" height="411" alt="Fig. 232" />
+<br />
+Fig. 232.&mdash;Skull of <i>Dinoceras mirabilis</i>, greatly
+reduced. Eocene, North America. (After Marsh.)
+</span>
+</span>
+
+Many forms of the <i>Dinocerata</i> are known; but all these
+singular and gigantic quadrupeds appear to have been confined
+to the North American continent, and to be restricted to the
+Eocene period.
+</p>
+
+<p class="indent">
+The important order of the Elephants (<i>Proboscidea</i>) is
+also not known to have come into existence during the Eocene
+period. On the other hand, the great order of the Beasts of Prey
+(<i>Carnivora</i>) is represented in Eocene strata by several
+forms belonging to different types. Thus the <i>Ardocyon</i>
+presents us with an Eocene Carnivore more or less closely allied
+to the existing Racoons; the <i>Palœonyctis</i> appears to
+be related to the recent Civet-cats; the genus <i>Hyœnodon</i>
+is in some respects comparable to the living Hyænas; and the
+<i>Canis Parisiensis</i> of the gypsum-bearing beds of Montmartre
+may perhaps be allied to the Foxes.
+</p>
+
+<p class="indent">
+The order of the Bats (<i>Cheiroptera</i>) is represented in Eocene
+strata of the Paris basin (Gypseous series of Montmartre) by the
+<i>Vespertilio Parisiensis</i> (fig. 233), an insect-eating Bat
+very similar to some of the existing European forms. Lastly, the
+Eocene deposits have yielded more or less satisfactory evidence of
+<a name="page_305"><span class="page">Page 305</span></a>
+the existence in Europe at this period of examples of the orders
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 451px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig233.jpg" width="451" height="370" alt="Fig. 233" />
+<br />
+Fig. 233.&mdash;Portion of the skeleton of <i>Vespertilio
+Parisienis</i>. Eocene Tertiary, France.
+</span>
+</span>
+
+of the Gnawing Mammals (<i>Rodentia</i>), the Insect-eating Mammals
+(<i>Insectivora</i>), and the Monkeys (<i>Quadrumana</i>).[24]
+</p>
+
+<p class="footnote">
+[Footnote 24: A short list of the more important works relating to
+the Eocene rocks and fossils will be given after all the Tertiary
+deposits have been treated of.]
+</p>
+
+<h3>CHAPTER XIX.</h3>
+
+<p class="subtitle">
+THE MIOCENE PERIOD.
+</p>
+
+<p class="indent">
+The Miocene rocks comprise those Tertiary deposits which contain
+less than about 35 per cent of existing species of shells
+(<i>Mollusca</i>), and more than 5 per cent&mdash;or those deposits
+in which the proportion of living shells is less than of extinct
+species. They are divisible into a <i>Lower Miocene</i>
+(<i>Oligocene</i>) and an <i>Upper Miocene</i> series.
+</p>
+
+<p class="indent">
+In <i>Britain</i>, the Miocene rocks are very poorly developed, one
+of their leading developments being at Bovey Tracy in Devonshire,
+where there occur sands, clays, and beds of lignite
+<a name="page_306"><span class="page">Page 306</span></a>
+or imperfect coal. These strata contain numerous plants,
+amongst which are Vines, Figs, the Cinnamon-tree, Palms, and many
+Conifers, especially those belonging to the genus Sequoia (the
+"Red-Foods"). These Bovey Tracy lignites are of Lower Miocene age,
+and they are lacustrine in origin. Also of Lower Miocene age are
+the so-called "Hempstead Beds" of Yarmouth in the Isle of Wight.
+These attain a thickness of less than 200 feet, and are shown by
+their numerous fossils to be principally a true marine formation.
+Lastly, the Duke of Argyll, in 1851, showed that there existed at
+Ardtun, in the island of Mull, certain Tertiary strata containing
+numerous remains of plants; and these also are now regarded as
+belonging to the Lower Miocene.
+</p>
+
+<p class="indent">
+In <i>France</i>, the Lower Miocene is represented in Auvergne,
+Cantal, and Velay, by a great thickness of nearly horizontal
+strata of sands, sandstone, clays, marls, and limestones, the
+whole of fresh-water origin. The principal fossils of these
+lacustrine deposits are <i>Mammalia</i>, of which the remains
+occur in great abundance. In the valley of the Loire occur the
+typical European deposits of Upper Miocene age. These are known
+as the "Faluns," from a provincial term applied to shelly sands,
+employed to spread upon soils which are deficient in lime; and
+the Upper Miocene is hence sometimes spoken of as the "Falunian"
+formation. The Faluns occur in scattered patches, which are rarely
+more than 50 feet in thickness, and consist of sands and marls.
+The fossils are chiefly marine; but there occur also land and
+fresh-water shells, together with the remains of numerous Mammals.
+About 25 per cent of the shells of the Faluns are identical with
+existing species. The sands, limestones, and marls of the Department
+of Gers, near the base of the Pyrenees, rendered famous by the
+number or Mammalian remains exhumed from them by M. Lartet, also
+belong to the age of the Faluns.
+</p>
+
+<p class="indent">
+In <i>Switzerland</i>, between the Alps and the Jura, there occurs
+a great series of Miocene deposits, known collectively as the
+"Molasse," from the soft nature of a greenish sandstone, which
+constitutes one of its chief members. It attains a thickness of
+many thousands of feet, and rises into lofty mountains, some of
+which&mdash;as the Rigi&mdash;are more than 6000 feet in height.
+The middle portion of the Molasse is of marine origin, and is
+shown by its fossils to be of the age of the Faluns; but the
+lower and upper portions of the formation are mainly or entirely
+of fresh-water origin. The Lower Molasse (of Lower Miocene age)
+has yielded about 500 species of plants, mostly of tropical or
+sub-tropical forms. The Upper
+<a name="page_307"><span class="page">Page 307</span></a>
+Molasse has yielded about the same number of plants, with about
+900 species of Insects, such as wood-eating Beetles Water-beetles,
+White Ants, Dragon-flies, &amp;c.
+</p>
+
+<p class="indent">
+In <i>Belgium</i>, strata of both Lower and Upper Miocene age are
+known,&mdash;the former (<i>Rupelian Clays</i>) containing numerous
+marine fossils; whilst the latter (<i>Bolderberg Sands</i>) have
+yielded numerous shells corresponding with those of the Faluns.
+</p>
+
+<p class="indent">
+In <i>Austria</i>, Miocene strata are largely developed, marine
+beds belonging to both the Lower and Upper division of the formation
+occurring extensively in the Vienna basin. The well-known Brown
+Coals of Radaboj, in Croatia, with numerous plants and insects,
+are also of Lower Miocene age.
+</p>
+
+<p class="indent">
+In <i>Germany</i>, deposits belonging to both the Lower and Upper
+division of the Miocene formation are extensively developed. To
+the former belong the marine strata of the Mayence basin, and
+the marine <i>Rupelian Clay</i> near Berlin; whilst a celebrated
+group of strata belonging to the Upper Miocene occurs near
+Epplesheim, in Hesse-Darmstadt, and is well known for the number
+of its Mammalian remains.
+</p>
+
+<p class="indent">
+In <i>Greece</i>, at Pikermé, near Athens, there occurs a
+celebrated deposit of Upper Miocene age, well known to
+palæontologists through the researches of M. M. Wagner, Roth,
+and Gaudry upon the numerous Mammalia which it contains. In
+<i>Italy</i>, also, strata of both Lower and Upper Miocene age are
+well developed in the neighbourhood of Turin.
+</p>
+
+<p class="indent">
+In the <i>Siwâlik Hills</i>, in India, at the southern foot
+of the Himalayas, occurs a series of Upper Miocene strata, which
+have become widely celebrated through the researches of Dr Falconer
+and Sir Proby Cautley upon the numerous remains of Mammals and
+Reptiles which they contain. Beds of corresponding age, with
+similar fossils, are known to occur in the island of Perim in
+the Gulf of Cambay.
+</p>
+
+<p class="indent">
+Lastly, Miocene deposits are found in <i>North America</i>, in
+New Jersey, Maryland, Virginia, Missouri, California, Oregon,
+&amp;c., attaining a thickness of 1500 feet or more. They consist
+principally of clays, sands, and sandstones, sometimes of marine
+and sometimes of fresh-water origin. Near Richmond, in Virginia,
+there occurs a remarkable stratum, wrongly called "Infusorial
+Earth," which is occasionally 30 feet in thickness, and consists
+almost wholly of the siliceous envelopes of certain low forms of
+plants (Diatoms), along with the spicules of Sponges and other
+siliceous organisms (see fig. 16). The <i>White River Group</i> of
+Hayden occurs in the Upper Missouri region, and is largely exposed
+over the barren and desolate
+<a name="page_308"><span class="page">Page 308</span></a>
+district known as the "Mauvaises Terres." They have a thickness of
+1000 feet or more, and contain numerous remains of Mammals. They
+are of lacustrine origin, and are believed to be of the age of the
+Lower Miocene. Upon the whole, about from 15 to 30 per cent of the
+<i>Mollusca</i> of the American Miocene are identical with
+existing species.
+</p>
+
+<p class="indent">
+In addition to the regions previously enumerated, Miocene strata
+are known to be developed in <i>Greenland, Iceland, Spitzbergen</i>,
+and in other areas of less importance.
+</p>
+
+<p class="indent">
+The <i>life</i> of the Miocene period is extremely abundant,
+and, from the nature of the deposits of this age, also extremely
+varied in its character. The marine beds of the formation have
+yielded numerous remains of both Vertebrate and Invertebrate
+sea-animals; whilst the fresh-water deposits contain the skeletons
+of such shells, fishes, &amp;c., as now inhabit rivers or lakes.
+Both the marine and the lacustrine beds have been shown to contain
+an enormous number of plants, the latter more particularly; whilst
+the Brown Coals of the formation are made up of vegetable matter
+little altered from its original condition. The remains of
+air-breathing animals, such as Insects, Reptiles, Birds, and
+Mammals, are also abundantly found, more especially in the
+fresh-water beds.
+</p>
+
+<p class="indent">
+The <i>plants</i> of the Miocene period are extraordinarily numerous,
+and only some of the general features of the vegetation of this
+epoch can be indicated here. Our chief sources of information as
+to the Miocene plants are the Brown Coals of Germany and Austria,
+the Lower and Upper Molasse of Switzerland, and the Miocene strata
+of the Arctic regions. The lignites of Austria have yielded very
+numerous plants, chiefly of a tropical character&mdash;one of the
+most noticeable forms being a Palm of the genus <i>Sabal</i>
+(fig. 234, B), now found in America. The plants of the Lower
+Miocene of Switzerland are also mostly of a tropical character,
+but include several forms now found in North America, such as a
+Tulip-tree (<i>Liriodendron</i>) and a Cypress (<i>Taxodium</i>).
+Amongst the more remarkable forms from these beds may be mentioned
+Fan-Palms (<i>Chamœrops</i>, fig. 234, A), numerous tropical
+ferns, and two species of Cinnamon. The plant-remains of the
+Upper Molasse of Switzerland indicate an extraordinarily rank and
+luxuriant vegetation, composed mainly of plants which now live
+in warm countries. Among the commoner plants of this formation may
+be enumerated many species of Maple (<i>Acer</i>), Plane-trees
+(<i>Platanus</i> fig. 235), Cinnamon-trees (fig. 236), and other
+members of the <i>Lauraceœ</i>, many species of
+<i>Proteaccœ</i> (<i>Banksia, Grevillea</i>, &amp;c.),
+several species of Sarsaparilla (<i>Smilax</i>), Palms, Cypresses,
+&amp;c.
+</p>
+
+<p class="indent">
+<a name="page_309"><span class="page">Page 309</span></a>
+In Britain, the Lower Miocene strata of Bovey Tracy have yielded
+remains of Ferns, Vines, Fig, Cinnamon, <i>Proteaccœ</i>, &amp;c.,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 513px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig234.jpg" width="513" height="253" alt="Fig. 234" />
+<br />
+Fig. 234.&mdash;Miocene Palms A, <i>Chamœrops Helvetica</i>; B,
+<i>Sabal major</i>. Lower Miocene of Switzerland and France.
+</span>
+</span>
+
+along with numerous Conifers. The most abundant of these last is a
+gigantic pine&mdash;the <i>Sequoia Couttsiœ</i>&mdash;which is
+
+<span style="float: left; width: 100%;
+  text-align: center; font-size: smaller;">
+
+<span style="width: 217px; vertical-align:bottom; text-align: justify;
+  margin: 12px;">
+<img src="images/fig235.jpg" width="217" height="217" alt="Fig. 235" />
+<br />
+Fig. 235.&mdash;<i>Platanus aceroides</i>, an Upper Miocene
+Plane-tree. <i>a</i>, Leaf; <i>b</i>, The core of a bundle
+of fruits; <i>c</i>, A single fruit.
+</span>
+
+<span style="width: 168px; vertical-align:bottom; text-align: center;
+  margin: 12px;">
+<img src="images/fig236.jpg" width="128" height="248" alt="Fig. 236" />
+<br />
+Fig. 236.&mdash;<i>Cinnamomum polymorphum</i>. <i>a</i>, Leaf;
+<i>b</i>, Flower. Upper Miocene.
+</span>
+
+</span>
+
+very nearly allied to the huge <i>Sequoia</i> (<i>Wellingtonia</i>)
+<i>gigantea</i> of California. A nearly-allied form (<i>Sequoia
+Langsdorffi</i>) has been detected in the leaf-bed of Ardtun,
+in the Hebrides.
+</p>
+
+<p class="indent">
+In Greenland, as well as in other parts of the Arctic regions,
+Miocene strata have been discovered which have yielded a great
+number of plants, many of which are identical with species found
+in the European Miocene. Amongst these
+<a name="page_310"><span class="page">Page 310</span></a>
+plants are found many trees, such as Conifers, Beeches, Oaks,
+Maples, Plane-trees, Walnuts, Magnolias, &amp;c., with numerous
+shrubs, ferns, and other smaller plants. With regard to the Miocene
+flora of the Arctic regions, Sir Charles Lyell remarks that "more
+than thirty species of Coniferæ have been found, including
+several Sequoias (allied to the gigantic Wellingtonia of California),
+with species of <i>Thujopsis</i> and <i>Salisburia</i>, now peculiar
+to Japan. There are also beeches, oaks, planes, poplars, maples,
+walnuts, limes, and even a magnolia, two cones of which have
+recently been obtained, proving that this splendid evergreen not
+only lived but ripened its fruit within the Arctic circle. Many
+of the limes, planes, and oaks were large-leaved species; and both
+flowers and fruits, besides immense quantities of leaves, are in
+many cases preserved. Among the shrubs are many evergreens, as
+<i>Andromeda</i>, and two extinct genera, <i>Daphnogene</i> and
+<i>M'Clintockia</i>, with fine leathery leaves, together with
+hazel, blackthorn, holly, logwood, and hawthorn. A species of
+Zamia (<i>Zimites</i>) grew in the swamps, with <i>Potamogeton,
+Sparganium</i>, and <i>Menyanthes</i>; while ivy and villes twined
+around the forest-trees, and broad-leaved ferns grew beneath their
+shade. Even in Spitzbergen, as far north as lat. 78&deg; 56', no
+less than ninety-five species of fossil plants have been obtained,
+including <i>Taxodium</i> of two species, hazel, poplar, alder,
+beech, plane-tree, and lime. Such a vigorous growth of trees within
+12&deg; of the pole, where now a dwarf willow and a few herbaceous
+plants form the only vegetation, and where the ground is covered
+with almost perpetual snow and ice, is truly remarkable."
+</p>
+
+<p class="indent">
+Taking the Miocene flora as a whole, Dr Heer concludes from his
+study of about 3000 plants contained in the European Miocene
+alone, that the Miocene plants indicate tropical or sub-tropical
+conditions, but that there is a striking inter-mixture of forms
+which are at present found in countries widely removed from one
+another. It is impossible to state with certainty how many of the
+Miocene plants belong to existing species, but it appears that
+the larger number are extinct. According to Heer, the American
+types of plants are most largely represented in the Miocene flora,
+next those of Europe and Asia, next those of Africa, and lastly
+those of Australia. Upon the whole, however, the Miocene flora
+of Europe is mostly nearly allied to the plants which we now
+find inhabiting the warmer parts of the United States; and this
+has led to the suggestion that in Miocene times the Atlantic
+Ocean was dry land, and that a migration of
+<a name="page_311"><span class="page">Page 311</span></a>
+American plants to Europe was thus permitted. This view is
+borne out by the fact that the Miocene plants of Europe are most
+nearly allied to the living plants of the eastern or Atlantic
+seaboard of the United States, and also by the occurrence of a
+rich Miocene flora in Greenland. As regards Greenland, Dr Heer
+has determined that the Miocene plants indicate a temperate
+climate in that country, with a mean annual temperature at least
+30&deg; warmer than it is at present.
+</p>
+
+<p class="indent">
+The present limit of trees is the isothermal which gives the
+mean temperature of 500 Fahr. in July, or about the parallel of
+67&deg; N. latitude. In Miocene times, however, the Limes, Cypresses,
+and Plane-trees reach the 79th degree of latitude, and the Pines
+and Poplars must have ranged even further north than this.
+</p>
+
+<p class="indent">
+The <i>Invertebrate Animals</i> of the Miocene period are very
+numerous, but they belong for the most part to existing types,
+and they can only receive scanty consideration here. The little
+shells of <i>Foraminifera</i> are extremely abundant in some beds,
+the genera being in many cases such as now flourish abundantly in
+our seas. The principal forms belong to the genera <i>Textularia</i>
+(fig. 237), <i>Robulina, Glandulina, Polystomella, Amplistegina</i>,
+
+<span style="float: right; margin: 4px; width: 268px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig237.jpg" width="268" height="176" alt="Fig. 237" />
+<br />
+Fig. 237.&mdash;<i>Textularia Meyeriana</i>, greatly
+enlarged. Miocene Tertiary.
+</span>
+
+&amp;c. Corals are very abundant, in many instances forming regular
+"reefs;" but all the more important groups are in existence at
+the present day. The Red Coral (<i>Corallium</i>), so largely
+sought after as an ornamental material, appears for the first
+time in deposits of this age. Amongst the <i>Echinoderms</i>,
+we meet with Heart-Urchins (<i>Spatangus</i>), Cake-Urchins
+(<i>Scutella</i>; fig. 238), and various other forms, the majority
+of which are closely allied to forms now in existence.
+</p>
+
+<p class="indent">
+Numerous Crabs and Lobsters represent the <i>Crustacea</i>; but
+the most important of the Miocene Articulate Animals are the
+<i>Insects</i>. Of these, more than thirteen hundred species
+have been determined by Dr Heer from the Miocene strata of
+Switzerland alone. They include almost all the existing orders
+of insects, such as numerous and varied forms of Beetles
+(<i>Coleoptera</i>), Forest-bugs (<i>Hemiptera</i>), Ants
+(<i>Hymenoptera</i>), Flies (<i>Diptera</i>), Termites and
+Dragon-flies (<i>Neuroptera</i>), Grasshoppers (<i>Orthoptera</i>),
+and Butterflies (<i>Lepidoptera</i>).
+<a name="page_312"><span class="page">Page 312</span></a>
+One of the latter,
+the well-known <i>Vanessa Pluto</i> of the Brown Coals of Croatia,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 528px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig238.jpg" width="528" height="158" alt="Fig. 238" />
+<br />
+Fig. 238.&mdash;Different views of <i>Scutella subrotunda</i>,
+a Miocene "Cake-Urchin" from the south of France.
+</span>
+</span>
+
+even exhibits the pattern of the wing, and to some extent its
+original coloration; whilst the more durably-constructed insects
+are often in a state of exquisite preservation.
+</p>
+
+<p class="indent">
+The <i>Mollusca</i> of the Miocene period are very numerous,
+but call for little special comment. Upon the whole, they are
+generically very similar to the Shell-fish of the present day;
+whilst, as before stated, from fifteen to thirty per cent of
+the <i>species</i> are identical with those now in existence.
+So far as the European area is concerned, the Molluscs indicate
+a decidedly hotter climate than the present one, though they
+have not such a distinctly tropical character as is the case
+with the Eocene shells. Thus we meet with many Cones, Volutes,
+Cowries, Olive-shells, Fig-shells, and the like, which are
+decidedly indicative of a high temperature of the sea.
+<i>Polyzoans</i> are abundant, and often attain considerable
+dimensions; whilst <i>Brachiopods</i>, on the other hand, are
+few in number. Bivalves and <i>Univalves</i> are extremely
+plentiful; and we meet here with the shells of Winged-Snails
+(<i>Pteropods</i>), belonging to such existing genera as
+<i>Hyalea</i> (fig. 239) and <i>Cleodora</i>. Lastly, the
+
+<span style="float: left; margin: 4px; width: 245px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig239.jpg" width="245" height="79" alt="Fig. 239" />
+<br />
+Fig. 239.&mdash;Different views of the shell of <i>Hyalea
+Orbignyana</i>, a Miocene Pteropod.
+</span>
+
+<i>Cephalopods</i> are represented both by the chambered shells
+of <i>Nautili</i> and by the internal skeletons of Cuttle-fishes
+(<i>Spirulirostra</i>.)
+</p>
+
+<p class="indent">
+The <i>Fishes</i> of the Miocene Period are very abundant but of
+little special importance. Besides the remains of Bony Fishes, we
+meet in the marine deposits of this age with numerous pointed
+teeth belonging to different kinds of Sharks. Some of the genera of
+these&mdash;such as <i>Carcharodon</i> (fig. 241), <i>Oxyrhina</i>
+(fig. 240), <i>Lamna</i>, and <i>Galeocerdo</i>&mdash;are very
+widely distributed, ranging through
+<a name="page_313"><span class="page">Page 313</span></a>
+both the Old and New Worlds; and some of the species attain gigantic
+dimensions.
+</p>
+
+<table border="0" class="right">
+<tr><td align="center" valign="bottom">
+
+<table border="0" width="121">
+<tr><td>
+<img src="images/fig240.jpg" width="117" height="189" alt="Fig. 240" />
+</td></tr><tr><td class="left"><span class="image">
+Fig. 240.&mdash;Tooth of <i>Oxyrhina xiphodon</i>. Miocene.
+</span></td></tr>
+</table>
+
+</td><td align="center" valign="bottom">
+
+<table border="0" width="119">
+<tr><td>
+<img src="images/fig241.jpg" width="115" height="127" alt="Fig. 241" />
+</td></tr><tr><td class="left"><span class="image">
+Fig. 241.&mdash;Tooth of <i>Carcharodon productus</i>. Miocene.
+</span></td></tr>
+</table>
+
+</td></tr>
+</table>
+
+<p class="indent">
+Amongst the <i>Amphibians</i> we meet with distinctly modern
+types, such as Frogs (<i>Rana</i>) and Newts or Salamanders.
+The most celebrated of the latter is the famous <i>Andrias
+Scheuchzeri</i> (fig. 242), discovered in the year 1725 in the
+fresh-water Miocene deposits of Œningen, in Switzerland.
+The skeleton indicates an animal nearly five feet in length; and
+it was originally described by Scheuchzer, a Swiss physician, in
+a dissertation published in 1731, as the remains of one of the
+human beings who were in existence at the time of the Noachian
+Deluge. Hence he applied to it the name of <i>Homo diluvii
+testis</i>. In reality, however, as shown by Cuvier, we have here
+the skeleton of a huge Newt, very closely allied to the Giant
+Salamander (<i>Menopoma maxima</i>) of Java.
+</p>
+
+<p class="indent">
+The remains of <i>Reptiles</i> are far from uncommon in the Miocene
+rocks, consisting principally of Chelonians and Crocodilians. The
+Land-tortoises (<i>Testudinidœ</i>) make their first appearance
+during this period. The most remarkable form of this group is the
+huge <i>Colossochelys Atlas</i> of the Upper Miocene deposits of
+the Siwâlik Hills in India, described by Dr Falconer and Sir
+Proby Cautley. Far exceeding any living Tortoise in its dimensions,
+this enormous animal is estimated as having had a length of about
+twenty feet, measured from the tip of the snout to the extremity
+of the tail, and to have stood upwards of seven feet high. All the
+details of its organisation, however, prove that it must have been
+"strictly a land animal, with herbivorous habits, and probably of
+the most inoffensive nature." The accomplished palæontologist
+just quoted, shows further that some of the traditions of the
+Hindoos would render it not improbable that this colossal Tortoise
+had survived into the earlier portion of the human period.
+</p>
+
+<p class="indent">
+Of the <i>Birds</i> of the Miocene period it is sufficient to
+remark that though specifically distinct, they belong, so far
+as known, wholly to existing groups, and therefore present no
+points of special palæontological interest.
+</p>
+
+<p class="indent">
+The <i>Mammals</i> of the Miocene are very numerous, and only
+<a name="page_314"><span class="page">Page 314</span></a>
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 462px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig242.jpg" width="462" height="858" alt="Fig. 242" />
+<br />
+Fig. 242.&mdash;Front portion of the skeleton of <i>Andrias
+Scheuchzeri</i>, a Giant Salamander from the Miocene Tertiary of
+Œningen, in Switzerland. Reduced in size.
+</span>
+</span>
+
+<a name="page_315">
+the more important forms can be here alluded to. Amongst the</a>
+<i>Marsupials</i>, the Old World still continued to possess species
+<span class="page">Page 315</span>
+of Opossum (<i>Didephys</i>), allied to the existing American
+forms. The <i>Edentates</i> (Sloths, Armadillos, and Ant-eaters),
+at the present day mainly South American, are represented by two
+large European forms. One of these is the large <i>Macrotherium
+giganteum</i> of the Upper Miocene of Gers in Southern France,
+which appears to hare been in many respects allied to the existing
+Scaly Ant-eaters or Pangolins, at the same time that the
+disproportionately long fore-limbs would indicate that it possessed
+the climbing habits of the Sloths. The other is the still more
+gigantic <i>Ancylotherium Pentelici</i> of the Upper Miocene of
+Pikermé, which seems to have been as large as, or larger than,
+the Rhinoceros, and which must have been terrestrial in its habits.
+This conclusion is further borne out by the comparative equality
+of length which subsists between the fore and hind limbs, and is
+not affected by the curvature and crookedness of the claws, this
+latter feature being well marked in such existing terrestrial
+Edentates as the Great Ant-eater.
+</p>
+
+<p class="indent">
+The aquatic <i>Sirenians</i> and <i>Cetaceans</i> are represented
+in Miocene times by various forms of no special importance. Amongst
+the former, the previously existing genus <i>Halitherium</i>
+continued to survive, and amongst the latter we meet with remains
+of Dolphins and of Whales of the "Zeuglodont" family. We may
+also note here the first appearance of true "Whalebone Whales,"
+two species of which, resembling the living "Right Whale" of
+Arctic seas, and belonging to the same genus (<i>Balœna</i>),
+have been detected in the Miocene beds of North America.
+</p>
+
+<p class="indent">
+The great order of the <i>Ungulates</i> or Hoofed Quadrupeds
+is very largely developed in strata of Miocene age, various new
+types of this group making their appearance here for the first
+time, whilst some of the characteristic genera of the preceding
+period are still represented under new shapes. Amongst the Odd-toed
+or "Perissodactyle" Ungulates, we meet for the first time with
+representatives of the family <i>Rhinoceridœ</i> comprising
+only the existing Rhinoceroses. In India in the Upper Miocene beds
+of the Siwâlik Hills, and in North America, several species
+of Rhinoceros have been detected, agreeing with the existing forms
+in possessing three toes to each foot, and in having one or two
+solid fibrous "horns" carried upon the front of the head. On the
+other hand, the forms of this group which distinguish the Miocene
+deposits of Europe appear to have been for the most part hornless,
+and to have resembled the Tapirs in having three-toed hind-feet,
+but four-toed fore-feet.
+<a name="page_316"><span class="page">Page 316</span></a>
+The family of the Tapirs is represented, both in the Old and New
+Worlds, by species of the genus <i>Lophiodon</i>, some of which
+were quite diminutive in point of size, whilst others attained
+the dimensions of a horse. Nearly allied to this family, also,
+is the singular group of quadrupeds which Marsh has described
+from the Miocene strata of the United States under the name of
+<i>Brontotheridœ</i>. These extraordinary animals, typified
+by <i>Brontotherium</i> (fig. 243) itself, agree with the existing
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 457px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig243.jpg" width="457" height="238" alt="Fig. 243" />
+<br />
+Fig. 243.&mdash;Skull of <i>Brontotherium ingens</i>. Miocene
+Tertiary, United States. (After Marsh.)
+</span>
+</span>
+
+Tapirs of South America and the Indian Archipelago in having the
+fore-feet four-toed, whilst the hind-feet are three-toed; and
+a further point of resemblance is found in the fact (as shown by
+the form of the nasal bones) that the nose was long and flexible,
+forming a short movable proboscis or trunk, by means of which the
+animal was enabled to browse on shrubs or trees. They differ,
+however, from the Tapirs, not only in the apparent presence of
+a long tail, but also in the possession of a pair of very large
+"horn-cores," carried upon the nasal bones, indicating that the
+animal possessed horns of a similar structure to those of the
+"Hollow-horned" Ruminants (<i>e.g.</i>, Sheep and Oxen).
+<i>Brontotherium gigas</i> is said to be nearly as large as an
+Elephant, whilst <i>B. Ingens</i> appears to have attained dimensions
+still more gigantic. The well-known genus <i>Titanotherium</i> of
+the American Miocene would also appear to belong to this group.
+</p>
+
+<p class="indent">
+The family of the Horses (<i>Equidœ</i>) appears under
+various forms in the Miocene, but the most important and best
+known of these is <i>Hipparion</i>. In this genus the general
+conformation of the skeleton is extremely similar to that of the
+existing Horses, and the external appearance of the animal must
+have been very much the same. The foot of <i>Hipparion</i>,
+<a name="page_317"><span class="page">Page 317</span></a>
+however, as has been previously mentioned,
+differed from that of the Horse in the fact that whilst both
+possess the middle toe greatly developed and enclosed in a
+broad hoof, the former, in addition, possessed two lateral
+toes, which were sufficiently developed to carry hoofs, but
+were so far rudimentary that they hung idly by the side of the
+central toe without touching the ground (see fig. 230). In the
+Horse, on the other hand, these lateral toes, though present,
+are not only functionally useless, but are concealed beneath
+the skin. Remains of the <i>Hipparion</i> have been found in
+various regions in Europe and in India; and from the immense
+quantities of their bones found in certain localities, it may
+be safely inferred that these Middle Tertiary ancestors of the
+Horses lived, like their modern representatives, in great
+herds, and in open grassy plains or prairies.
+</p>
+
+<p class="indent">
+Amongst the Even-toed or <i>Artiodactyle</i> Ungulates, we for
+the first time meet with examples of the <i>Hippopotamus</i>, with
+its four-toed feet, its massive body, and huge tusk-like lower
+canine teeth. The Miocene deposits of Europe have not hitherto
+yielded any remains of <i>Hippopotamus</i>; but several species
+have been detected in the Upper Miocene of the Siwâlik Hills
+by Dr Falconer and Sir Proby Cautley. These ancient Indian forms,
+however, differ from the existing <i>Hippopotamus amphibius</i>
+of Africa in the fact that they possessed six incisor teeth in
+each jaw (fig. 244), whereas the latter has only four.
+</p>
+
+<p class="indent">
+Amongst the other Even-toed Ungulates, the family of the Pigs
+(<i>Suida</i>) is represented by true Swine (<i>Sus Erymanthius</i>),
+Peccaries (<i>Dicotyles antiquus</i>), and by forms which, like
+the great <i>Elotherium</i> of the American Miocene, have no
+representative at the present day. The Upper Miocene of India has
+yielded examples of the Camels. Small Musk-deer (<i>Amphitragulus</i>
+and <i>Dremotherium</i>) are known to have existed in France and
+Greece; and the true Deer (<i>Cervidœ</i>), with their solid
+bony antlers, appear for the first time here in the person of
+species allied to the living Stags (<i>Cervus</i>), accompanied
+by the extinct genus <i>Dorcatherium</i>. The Giraffes
+(<i>Camelopardalidœ</i>), now confined to Africa, are known to
+have lived in India and Greece; and the allied <i>Helladotherium</i>,
+in some respects intermediate between the Giraffes and the Antelopes,
+ranged over Southern Europe from Attica to France. The great group
+of the "Hollow-horned" Ruminants (<i>Cavicornia</i>), lastly,
+came into existence in the Miocene period; and though the typical
+families of the Sheep and Oxen are apparently wanting, there are
+true Antelopes, together with forms which, if systematically
+referable to the <i>Antilopidœ</i>, nevertheless are more or
+less clearly transitional between this and the family of the Sheep
+<a name="page_318"><span class="page">Page 318</span></a>
+and Goats. Thus the <i>Palœoreas</i> of
+the Upper Miocene of Greece may be regarded as a genuine Antelope;
+but the <i>Tragoceras</i> of the same deposit is intermediate in
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 521px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig244.jpg" width="521" height="447" alt="Fig. 244" />
+<br />
+Fig. 244.&mdash;<i>a</i>, Skull of <i>Hippopotamus Sivalensis</i>,
+viewed from below, one-eighth of the natural size; <i>b</i>, Molar
+tooth of the same, showing the surface of the crown, one-half of
+the natural size: <i>c</i>, Front of the lower jaw of the same,
+showing the six incisors and the tusk-like canines, one-eighth of
+the natural size. Upper Miocene, Siwâlik Hills; (After
+Falconer and Cautley.)
+</span>
+</span>
+
+its characters between the typical Antelopes and the Goats. Perhaps
+the most remarkable, however, of these Miocene Ruminants is the
+<i>Sivatherium giganteum</i> (fig. 245) of the Siwâlik Hills,
+in India. In this extraordinary animal there were two pairs of horns,
+supported by bony "horn-cores," so that there can be no hesitation
+in referring <i>Sivatherium</i> to the Cavicorn Ruminants. If all
+these horns had been simple, there would have been no difficulty
+in considering <i>Sivatherium</i> as simply a gigantic four-horned
+Antelope, essentially similar to the living <i>Antilope</i>
+(<i>Tetraceros</i>) <i>quadricornis</i> of India. The hinder pair
+of horns, however, is not only much larger than the front pair,
+but each possesses two branches or snags&mdash;a peculiarity
+not to be paralleled amongst any existing Antelope, save the
+abnormal Prongbuck (<i>Antilocapra</i>) of North America. Dr
+Murie, however, in an admirable memoir on the structure and
+relationships
+<a name="page_319"><span class="page">Page 319</span></a>
+of <i>Sivatherium</i>, has drawn attention
+to the fact that the Prongbuck sheds the <i>sheath</i> of its
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 477px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig245.jpg" width="477" height="442" alt="Fig. 245" />
+<br />
+Fig. 245.&mdash;Skull of <i>Sivatherium giganteum</i>, reduced
+in size. Miocene, India. (After Murie.)
+</span>
+</span>
+
+horns annually, and has suggested that this may also have been the
+case with the extinct form. This conjecture is rendered probable,
+amongst other reasons, by the fact that no traces of a horny
+sheath surrounding the horn-cores of the Indian fossil have been
+as yet detected. Upon the whole, therefore, we may regard the
+elephantine <i>Sivatherium</i> as being most nearly allied to
+the Prongbuck of Western America, and thus as belonging to the
+family of the Antelopes.
+</p>
+
+<p class="indent">
+It is to the Miocene period, again, to which we must refer the
+first appearance of the important order of the Elephants and their
+allies (<i>Proboscideans</i>), all of which are characterised by
+their elongated trunk-like noses, the possession of five toes to
+the foot, the absence of canine teeth, the development of two or
+more of the incisor teeth into long tusks, and the adaptation of
+the molar teeth to a vegetable diet. Only three generic groups of
+this order are known-namely, the extinct <i>Deinotherium</i>, the
+equally extinct <i>Mastodons</i>, and the <i>Elephants</i>; and all
+these three types are known to have been in existence as
+<a name="page_320"><span class="page">Page 320</span></a>
+early as the Miocene period, the first of them being exclusively
+confined to deposits of this age. Of the three, the genus
+<i>Deinotherium</i> is much the most abnormal in its characters; so
+much so, that good authorities regard it as really being one of the
+Sea-cows (<i>Sirenia</i>)&mdash;though this view has been rendered
+untenable by the discovery of limb-bones which can hardly belong
+to any other animal, and which are distinctly Proboscidean in
+type. The most celebrated skull of the Deinothere (fig. 246) is one
+
+<span style="float: left; margin: 4px; width: 232px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig246.jpg" width="232" height="263" alt="Fig. 246" />
+<br />
+Fig. 246.&mdash;Skull of <i>Deinotherium giganteum</i>, greatly
+reduced. From the Upper Micene of Germany.
+</span>
+
+which was exhumed from the Upper Miocene deposits of Epplesheim,
+in Hesse-Darmstadt, in the year 1836. This skull was four and a
+half feet in length, and indicated an animal larger than any
+existing species of Elephant. The upper jaw is destitute of incisor
+or canine teeth, but is furnished on each side with five molars,
+which are opposed to a corresponding series of grinding teeth in
+the lower jaw. No canines are present in the lower jaw; but the
+front portion of the jaw is abruptly bent downwards, and carries
+two huge tusk-like incisor teeth, which are curved downwards and
+backwards, and the use of which is rather problematical. Not
+only does the Deinothere occur in Europe, but remains belonging
+to this genus have also been detected in the Siwâlik Hills, in
+India.
+</p>
+
+<p class="indent">
+The true Elephants (<i>Elephas</i>) do not appear to have existed
+during the Miocene period in Europe, but several species have been
+detected in the Upper Miocene deposits of the Siwâlik Hills,
+in India. The fossil forms, though in all cases specifically, and
+in some cases even sub-generically, distinct, agree with those
+now in existence in the general conformation of their skeleton,
+and in the principal characters of their dentition. In all, the
+canine teeth are wanting in both jaws; and there are no incisor
+teeth in the lower jaw, whilst there are two incisors in the
+front of the upper jaw, which are developed into two huge "tusks."
+There are six molar teeth on each side of both the upper and lower
+jaw, but only one, or at most a part of two, is in actual use
+at any given time; and as this becomes worn away, it is pushed
+forward and replaced by its successor behind it. The molars are of
+<a name="page_321"><span class="page">Page 321</span></a>
+very large size, and are each composed of a number of transverse
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 479px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig247.jpg" width="479" height="534" alt="Fig. 247" />
+<br />
+Fig. 247.&mdash;A, Molar tooth of <i>Elephas planifrons</i>,
+one-third of the natural size, showing the grinding
+surface&mdash;from the Upper Miocene of India; B, Profile view
+of the last upper molar of <i>Mastodon Sivalensis</i>, one-third
+of the natural size&mdash;from the Upper Miocene of India. (After
+Falconer.)
+</span>
+</span>
+
+plates of enamel united together by ivory; and by the process
+of mastication, the teeth become worn down to a flat surface,
+crossed by the enamel-ridges in varying patterns; These patterns
+are different in the different species of Elephants, though constant
+for each; and they constitute one of the most readily available
+means of separating the fossil forms from one another. Of the
+seven Miocene Elephants of India, as judged by the characters of
+the molar, teeth, two are allied to the existing Indian Elephant,
+one is related to the living African Elephant, and the remaining
+four are in some respects intermediate between the true Elephants
+and the Mastodons.
+</p>
+
+<p class="indent">
+The <i>Mastodons</i>, lastly, though quite elephantine in their
+<a name="page_322"><span class="page">Page 322</span></a>
+general characters, possess molar teeth
+which have their crowns furnished with conical eminences or
+tubercles placed in pairs (fig. 247, B), instead of having the
+approximately flat surface characteristic of the grinders of the
+Elephants. As in the latter, there are two upper incisor teeth,
+which grow permanently during the life of the animal, and which
+constitute great tusks; but the Mastodons, in addition, often
+possess two lower incisors, which in some cases likewise grow
+into small tusks. Three species of <i>Mastodon</i> are known to
+occur in the Upper Miocene of the Siwâlik Hills of India;
+and the Miocene deposits of the European area have yielded the
+remains of four species, of which the best known are the <i>M.
+Longirostris</i> and the <i>M. Angustidens</i>.
+</p>
+
+<p class="indent">
+Whilst herbivorous Quadrupeds, as we have seen, were extremely
+abundant during Miocene times, and often attained gigantic
+dimensions, Beasts of Prey (<i>Carnivora</i>) were by no means
+wanting, most of the principal existing families of the order
+being represented in deposits of this age. Thus, we find aquatic
+Carnivores belonging to both the living groups of the Seals and
+Walruses; true Bears are wanting, but their place is filled by the
+closely-allied genus <i>Amphicyon</i>, of which various species
+are known; Weasels and Otters were not unknown, and the
+<i>Hyœnictis</i> and <i>Iditherium</i> of the Upper Miocene
+of Greece are apparently intermediate between the Civet-cats and
+the Hyænas; whilst the great Cats of subsequent periods are
+more than adequately represented by the huge "Sabre-toothed Tiger"
+(<i>Machairodus</i>), with its immense trenchant and serrated
+canine teeth.
+</p>
+
+<p class="indent">
+Amongst the <i>Rodent</i> Mammals, the Miocene rocks have yielded
+remains of Rabbits, Porcupines (such as the <i>Hystrix
+primigenius</i> of Greece), Beavers, Mice, Jerboas, Squirrels,
+and Marmots. All the principal living groups of this order were
+therefore differentiated in Middle Tertiary times.
+</p>
+
+<p class="indent">
+The <i>Cheiroptera</i> are represented by small insect-eating
+Bats; and the order of the Insectivorous Mammals is represented
+by Moles, Shrew-mice, and Hedgehogs.
+</p>
+
+<p class="indent">
+Lastly, the Monkeys (<i>Quadrumana</i>) appear to have existed
+during the Miocene period under a variety of forms, remains of
+these animals having been found both in Europe and in India; but
+no member of this order has as yet been detected in the Miocene
+Tertiary of the North American continent. Amongst the Old World
+Monkeys of the Miocene, the two most interesting are the
+<i>Pliopithecus</i> and <i>Dryopithecus</i> of France. The former
+of these (fig. 248) is supposed to have been most nearly related
+to the living <i>Semnopitheci</i> of Southern Asia, in
+<a name="page_323"><span class="page">Page 323</span></a>
+which case it must have possessed a long tail. The <i>Mesopithecus</i>
+of the Upper Miocene of Greece is also one of the lower Monkeys,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 334px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig248.jpg" width="334" height="268" alt="Fig. 248" />
+<br />
+Fig. 248.&mdash;Lower jaw of <i>Pliopithcus antiquus</i>. Upper
+Miocene, France.
+</span>
+</span>
+
+as it is most closely allied to the existing Macaques. On the
+other hand, the <i>Dryopithecus</i> of the French Upper Miocene
+is referable to the group of the "Anthropoid Apes," and is most
+nearly related to the Gibbons of the present day, in which the tail
+is rudimentary and there are no cheek-pouches. <i>Dryopithecus</i>
+was, also, of large size, equalling Man in stature, and apparently
+living amongst the trees and feeding upon fruits.
+</p>
+
+<h3>CHAPTER XX.</h3>
+
+<p class="subtitle">
+THE PLIOCENE PERIOD.
+</p>
+
+<p class="indent">
+The highest division of the Tertiary deposits is termed the
+<i>Pliocene</i> formation, in accordance with the classification
+proposed by Sir Charles Lyell. The Pliocene formations contain
+from 40 to 95 per cent of existing species of <i>Mollusca</i>,
+the remainders belonging to extinct species. They are divided
+by Sir Charles Lyell into two divisions, the Older Pliocene and
+Newer Pliocene.
+</p>
+
+<p class="indent">
+The Pliocene deposits of Britain occur in Suffolk, and are known
+by the name of "Crags," this being a local term used for certain
+shelly sands, which are employed in agriculture. Two of these
+Crags are referable to the Older Pliocene, viz.,
+<a name="page_324"><span class="page">Page 324</span></a>
+the White and Red Crags,&mdash;and one belongs to the Newer
+Pliocene, viz., the Norwich Crag.
+</p>
+
+<p class="indent">
+The <i>White or Coralline Crag</i> of Suffolk is the oldest of
+the Pliocene deposits of Britain, and is an exceedingly local
+formation, occurring in but a single small area, and having a
+maximum thickness of not more than 50 feet. It consists of soft
+sands, with occasional intercalations of flaggy limestone. Though
+of small extent and thickness, the Coralline Crag is of importance
+from the number of fossils which it contains. The name "Coralline"
+is a misnomer; since there are few true Corals, and the so-called
+"Corals" of the formation are really <i>Polyzoa</i>, often of
+very singular forms. The shells of the Coralline Crag are mostly
+such as inhabit the seas of temperate regions; but there occur
+some forms usually looked upon as indicating a warm climate.
+</p>
+
+<p class="indent">
+The <i>Upper</i> or <i>Red Crag</i> of Suffolk&mdash;like the
+Coralline Crag&mdash;has a limited geographical extent and a
+small thickness, rarely exceeding 40 feet. It consists of
+quartzose sands, usually deep red or brown in colour, and
+charged with numerous fossils.
+</p>
+
+<p class="indent">
+Altogether more than 200 species of shells are known from the
+Red Crag, of which 60 per cent are referable to existing species.
+The shells indicate, upon the whole, a temperate or even cold
+climate, decidedly less warm than that indicated by the organic
+remains of the Coralline Crag. It appears, therefore, that a
+gradual refrigeration was going on during the Pliocene period,
+commencing in the Coralline Crag, becoming intensified in the Red
+Crag, being still more severe in the Norwich Crag, and finally
+culminating in the Arctic cold of the Glacial period.
+</p>
+
+<p class="indent">
+Besides the <i>Mollusca</i>, the Red Crag contains the ear-bones of
+Whales, the teeth of Sharks and Rays, and remains of the Mastodon,
+Rhinoceros, and Tapir.
+</p>
+
+<p class="indent">
+The <i>Newer Pliocene</i> deposits are represented in Britain
+by the <i>Norwich Crag</i>, a local formation occurring near
+Norwich. It consists of incoherent sands, loams, and gravels,
+resting in detached patches, from 2 to 20 feet in thickness,
+upon an eroded surface of Chalk. The Norwich Crag contains a
+mixture of marine, land, and fresh-water shells, with remains of
+fishes and bones of mammals; so that it must have been deposited
+as a local sea-deposit near the mouth of an ancient river. It
+contains altogether more than 100 marine shells, of which 89
+per cent belong to existing species. Of the Mammals, the two
+most important are an Elephant (<i>Elephas meridionalis</i>),
+and the characteristic Pliocene Mastodon
+<a name="page_325"><span class="page">Page 325</span></a>
+(<i>M. Arvernensis</i>), which is hitherto the only Mastodon
+found in Britain.
+</p>
+
+<p class="indent">
+According to the most recent views of high authorities, certain
+deposits&mdash;such as the so-called "Bridlington Crag" of
+Yorkshire, and the "Chillesford beds" of Suffolk&mdash;are to
+be also included in the Newer Pliocene, upon the ground that
+they contain a small proportion of extinct shells. Our knowledge,
+however, of the existing Molluscan fauna, is still so far
+incomplete, that it may reasonably be doubted if these supposed
+extinct forms have actually made their final disappearance,
+whilst the strata in question have a strong natural connection
+with the "Glacial deposits," as shown by the number of Arctic
+Mollusca which they contain. Here, therefore, these beds will
+be included in the Post-Pliocene series, in spite of the fact
+that some of their species of shells are not known to exist at
+the present day.
+</p>
+
+<p class="indent">
+The following are the more important Pliocene deposits which have
+been hitherto recognised out of Britain:&mdash;
+</p>
+
+<p class="indent">
+1. In the neighbourhood of Antwerp occur certain "crags," which
+are the equivalent of the White and Red Crag in part. The lowest
+of these contains less than 50 per cent, and the highest 60 per
+cent, of existing species of shells, the remainder being extinct.
+</p>
+
+<p class="indent">
+2. Bordering the chain of the Apennines, in Italy, on both sides
+is a series of low hills made up of Tertiary strata, which are
+known as the Sub-Apennine beds. Part of these is of Miocene age,
+part is Older Pliocene, and a portion is Newer Pliocene. The
+Older Pliocene portion of the Sub-Apennines consists of blue or
+brown marls, which sometimes attain a thickness of 2000 feet.
+</p>
+
+<p class="indent">
+3. In the valley of the Arno, above Florence, are both Older
+and Newer Pliocene strata. The former consist of blue clays and
+lignites, with an abundance of plants. The latter consist of sands
+and conglomerates, with remains of large Carnivorous Mammals,
+Mastodon, Elephant, Rhinoceros, Hippopotamus, &amp;c.
+</p>
+
+<p class="indent">
+4. In Sicily, Newer Pliocene strata are probably more largely
+developed than anywhere else in the world, rising sometimes to a
+height of 3000 feet above the sea. The series consists of clays,
+marls, sands, and conglomerates, capped by a compact limestone,
+which attains a thickness of from 700 to 800 feet. The fossils of
+these beds belong almost entirely to living species, one of the
+commonest being the Great Scallop of the Mediterranean (<i>Pecten
+Jacobœus</i>).
+</p>
+
+<p class="indent">
+5. Occupying an extensive area round the Caspian, Aral,
+<a name="page_326"><span class="page">Page 326</span></a>
+and Azof Seas, are Pliocene deposits known
+as the "Aralo-Caspian" beds. The fossils in these beds are partly
+freshwater, partly marine, and partly intermediate in character,
+and they are in great part identical with species now inhabiting
+the Caspian. The entire formation appears to indicate the former
+existence of a great sheet of brackish water, forming an inland
+sea, like the Caspian, but as large as, or larger than, the
+Mediterranean.
+</p>
+
+<p class="indent">
+6. In the United States, strata of Pliocene age are found in
+North and South Carolina. They consist of sands and clays, with
+numerous fossils, chiefly <i>Molluscs</i> and <i>Echinoderms</i>.
+From 40 to 60 per cent of the fossils belong to existing species.
+On the Loup Fork of the river Platte, in the Upper Missouri region,
+are strata which are also believed to be referable to the Pliocene
+period, and probably to its upper division. They are from 300 to
+400 feet thick, and contain land-shells, with the bones of numerous
+Mammals, such as Camels, Rhinoceroses, Mastodons, Elephants, the
+Horse, Stag, &amp;c.
+</p>
+
+<p class="indent">
+As regards the <i>life</i> of the Pliocene period, there are
+only two classes of organisms to which our attention need be
+directed&mdash;namely, the Shell-fish and the Mammals. So far as
+the former are concerned, we have to note in the first place that
+the introduction of new species of animals upon the globe went
+on rapidly during this period. In the Older Pliocene deposits,
+the number of shells of existing species is only from 40 to 60
+per cent; but in the Newer Pliocene the proportion of living
+forms rises to as much as from 80 to 95 per cent. Whilst the
+Molluscs thus become rapidly modernised, the Mammals still all
+belong to extinct species, though modern generic types gradually
+supersede the more antiquated forms of the Miocene. In the second
+place, there is good evidence to show that the Pliocene period
+was one in which the climate of the northern hemisphere underwent
+a gradual refrigeration. In the Miocene period, there is evidence
+to show that Europe possessed a climate very similar to that
+now enjoyed by the Southern United States, and certainly very
+much warmer than it is at present. The presence of Palm-trees
+upon the land, and of numerous large Cowries, Cones, and other
+shells of warm regions in the sea, sufficiently proves this. In
+the Older Pliocene deposits, on the other hand, northern forms
+predominate amongst the Shells, though some of the types of hotter
+regions still survive. In the Newer Pliocene, again, the Molluscs
+are such as almost exclusively inhabit the seas of temperate
+or even cold regions; whilst if we regard deposits like the
+"Bridlington Crag" and
+<a name="page_327"><span class="page">Page 327</span></a>
+"Chillesford beds"
+as truly referable to this period, we meet at the close of this
+period with shells such as nowadays are distinctively
+characteristic of high latitudes. It might be thought that the
+occurrence of Quadrupeds such as the Elephant, Rhinoceros, and
+Hippopotamus, would militate against this generalisation, and
+would rather support the view that the climate of Europe and
+the United States must have been a hot one during the later
+portion of the Pliocene period. We have, however, reason to
+believe that many of these extinct Mammals were more abundantly
+furnished with hair, and more adapted to withstand a cool
+temperature, than any of their living congeners. We have also
+to recollect that many of these large herbivorous quadrupeds
+may have been, and indeed probably were, more or less migratory
+in their habits; and that whilst the winters of the later portion
+of the Pliocene period were cold, the summers might have been
+very hot. This would allow of a northward migration of such
+terrestrial animals during the summer-time, when there would be
+an ample supply of food and a suitably high temperature, and a
+southward recession towards the approach of winter.
+</p>
+
+<p class="indent">
+The chief palæontological interests of the Pliocene deposits,
+as of the succeeding Post-Pliocene, centre round the Mammals of the
+period; and amongst the many forms of these we may restrict our
+attention to the orders of the Hoofed Quadrupeds (<i>Ungulates</i>),
+the <i>Proboscideans</i>, the <i>Carnivora</i>, and the
+<i>Quadrumana</i>. Almost all the other Mammalian orders are
+more or less fully represented in Pliocene times, but none of them
+attains any special interest till we enter upon the Post-Pliocene.
+</p>
+
+<p class="indent">
+Amongst the Odd-toed Ungulates, in addition to the remains of
+true Tapirs (<i>Tapirus Arvernensis</i>), we meet with the bones
+of several species of Rhinoceros, of which the <i>Rhinoceros
+Etruscus</i> and <i>R. Megarhinus</i> (fig. 249) are the most
+important. The former of these (fig. 249, A) derives its specific
+name from its abundance in the Pliocene deposits of the Val d'Arno,
+near Florence, and though principally Pliocene in its distribution,
+it survived into the earlier portion of the Post-Pliocene period.
+<i>Rhinoceros Etruscus</i> agreed with the existing African forms
+in having two horns placed one behind the other, the front one
+being the longest; but it was comparatively slight and slender in
+its build, whilst the nostrils were separated by an incomplete bony
+partition. In the <i>Rhinoceros megarhinus</i> (fig. 249, B), on
+the other hand, no such partition exists between the nostrils, and
+the nasal bones are greatly developed in size. It was a two-horned
+form, and is found associated with <i>Elephas meridionalis</i> and
+<i>E. Antiquus</i> in the Pliocene deposits of the
+<a name="page_328"><span class="page">Page 328</span></a>
+Val d'Arno, near Florence. Like the preceding, it survived, in
+diminished numbers, into the earlier portion of the Post-Pliocene
+period.
+</p>
+
+<p class="indent">
+The Horses (<i>Equidœ</i>) are represented, both in Europe
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 492px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig249.jpg" width="492" height="518" alt="Fig. 249" />
+<br />
+Fig. 249.&mdash;A. Under surface of the skull of <i>Rhinoceros
+Etruscus</i>, one-seventh of the natural size&mdash;Pliocene,
+Italy.; B, Crowns of the three true molars of the upper jaw,
+left side, of <i>Rhinoceros megarhinus</i> (<i>R. Leptorhinus</i>,
+Falconer), one-half of the natural size&mdash;Pliocene, France.
+(After Falconer.)
+</span>
+</span>
+
+and America, by the three-toed Hipparions, which survive from the
+Miocene, but are now verging upon extinction. For the first time,
+also, we meet with genuine Horses (<i>Equus</i>), in which each
+foot is provided with a single complete toe only, encased in a
+single broad hoof. One of the American species of this period
+(the <i>Equus excelsus</i>) quite equalled the modern Horse in
+stature; and it is interesting to note the occurrence of indigenous
+horses in America at such a comparatively late geological epoch,
+seeing that this continent certainly possessed none of these
+animals when first discovered by the Spaniards.
+</p>
+
+<p class="indent">
+Amongst the Even-toed Ungulates, we may note the occurrence of
+<a name="page_329"><span class="page">Page 329</span></a>
+Swine (<i>Suida</i>), of forms allied to
+the Camels (<i>Camelidœ</i>), and of various kinds of Deer
+(<i>Cervidœ</i>); but the most interesting Pliocene Mammal
+belonging to this section is the great <i>Hippopotamus major</i>
+of Britain and Europe. This well-known species is very closely
+allied to the living <i>Hippopotamus amphibius</i> of Africa,
+from which it is separated only by its larger dimensions, and by
+certain points connected with the conformation of the skeleton.
+It is found very abundantly in the Pliocene deposits of Italy
+and France, associated with the remains of the Elephant, Mastodon,
+and Rhinoceros, and it survived into the earlier portion of the
+Post-Pliocene period. During this last-mentioned period, it
+extended its range northwards, and is found associated with the
+Reindeer, the Bison, and other northern animals. From this fact
+it has been inferred, with great probability, that the
+<i>Hippotamus major</i> was furnished with a long coat of hair
+and fur, thus differing from its nearly hairless modern
+representative, and resembling its associates, the Mammoth and
+the Woolly Rhinoceros.
+</p>
+
+<p class="indent">
+Passing on to the Pliocene Proboscideans, we find that the great
+<i>Deinotheria</i> of the Miocene have now wholly disappeared,
+and the sole representatives of the order are Mastodons and
+Elephants. The most important member of the former group is the
+<i>Mastodon Arvernensis</i> (fig. 250), which ranged widely over
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 436px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig250.jpg" width="436" height="276" alt="Fig. 250" />
+<br />
+Fig. 250.&mdash;Third milk-molar of the left side of the upper
+jaw of <i>Mastodon Arvernensis</i>, showing the grinding surface.
+Pliocene.
+</span>
+</span>
+
+Southern Europe and England, being generally associated with
+remains of the <i>Elephas meridionalis, E. antiquus, Rhinoceros
+megarhinus</i>, and <i>Hippopotamus major</i>. The lower jaw
+seems to have been destitute of incisor teeth; but the upper
+incisors are developed into great tusks, which sometimes reach a
+<a name="page_330"><span class="page">Page 330</span></a>
+length of nine feet, and which have the simple curvature of the
+tusks of the existing Elephants. Amongst the Pliocene Elephants
+the two most important are the <i>Elephas meridionalis</i> and the
+<i>Elephas antiquus</i>. Of these, the <i>Elephas meridionalis</i>
+(fig. 251) is found abundantly in the Pliocene deposits of Southern
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 472px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig251.jpg" width="472" height="230" alt="Fig. 251" />
+<br />
+Fig. 251.&mdash;Molar tooth of <i>Elephas meridionalis</i>,
+one-third of the natural size. Pliocene and Post-Pliocene.
+</span>
+</span>
+
+Europe and England, and also survived into the earlier portion
+of the Post-Pliocene period. Its molar teeth are of the type of
+those of the existing African Elephant, the spaces enclosed by the
+transverse enamel-plates being more or less lozenge-shaped, whilst
+the curvature of the tusks is simple. The <i>Elephas antiquus</i>
+(fig. 252) is very generally associated with the preceding, and
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 421px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig252.jpg" width="421" height="148" alt="Fig. 252" />
+<br />
+Fig. 252.&mdash;Molar tooth of <i>Elephas antiquus</i>, one-third
+of the natural size. Pliocene and Post-Pliocene.
+</span>
+</span>
+
+it survived to an even later stage of the Post-Pliocene period.
+The molar teeth are of the type of the existing Indian Elephant,
+with comparatively thin enamel-ridges, placed closer together
+than in the African type; whilst the tusks were nearly straight.
+</p>
+
+<p class="indent">
+Amongst the Pliocene <i>Carnivores</i>, we meet with true Bears
+(<i>Ursus Arvernensis</i>), Hyænas (such as <i>Hyœna
+Hipparionum</i>), and genuine Lions (such as the <i>Felis
+angustus</i> of North America); but the most remarkable of the
+beasts of prey of
+<a name="page_331"><span class="page">Page 331</span></a>
+this period is the great "Sabre-toothed Tiger" (<i>Machairodus</i>),
+species of which existed in the earlier Miocene,
+and survived to the later Post-Pliocene. In this remarkable
+form we are presented with perhaps the most highly carnivorous
+type of all known beasts of prey. Not only are the jaws shorter
+in proportion even than those of the great Cats of the present
+day, but the canine teeth (fig. 253) are of enormous size, greatly
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 538px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig253.jpg" width="538" height="378" alt="Fig. 253" />
+<br />
+Fig. 253.&mdash;A, Skull of <i>Machairodus cultridens</i>,
+without the lower jaw, reduced in size; B, Canine tooth of the
+same, one-half the natural size. Pliocene, France.
+</span>
+</span>
+
+flattened so as to assume the form of a poignard, and having
+their margins finely serrated. A part from the characters of the
+skull, the remainder of the skeleton, so far as known, exhibits
+proofs that the Sabre-toothed Tiger was extraordinarily muscular
+and powerful, and in the highest degree adapted for a life of
+rapine. Species of <i>Machairodus</i> must have been as large
+as the existing Lion; and the genus is not only European, but
+is represented both in South America and in India, so that the
+geographical range of these predaceous beasts must have been
+very extensive.
+</p>
+
+<p class="indent">
+Lastly, we may note that the Pliocene deposits of Europe have
+yielded the remains of Monkeys (<i>Quadrumana</i>), allied to
+the existing <i>Semnopitheci</i> and Macaques.
+</p>
+
+<h4>
+<a name="page_332"><span class="page">Page 332</span></a>
+LITERATURE.</h4>
+
+<p class="indent">
+The following list comprises a small selection of some of the
+more important and readily accessible works and memoirs relating
+to the Tertiary rocks and their fossils. With few exceptions,
+foreign works relating to the Tertiary strata of the continent
+of Europe or their organic remains have been omitted:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Elements of Geology.' Lyell.</td>
+</tr><tr><td class="right" valign="top">(2)</td>
+ <td>'Students' Elements of Geology.' Lyell.</td>
+</tr><tr><td class="right" valign="top">(3)</td>
+ <td>'Manual of Palæontology.' Owen.</td>
+</tr><tr><td class="right" valign="top">(4)</td>
+ <td>'British Fossil Mammals and Birds.' Owen.</td>
+</tr><tr><td class="right" valign="top">(5)</td>
+ <td>'Traité de Paléontologie.' Pictet.</td>
+</tr><tr><td class="right" valign="top">(6)</td>
+ <td>'Cours Elémentaire de Paléontologie.' D'Orbigny.</td>
+</tr><tr><td class="right" valign="top">(7)</td>
+ <td>"Probable Age of the London Clay," &amp;c.&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. iii. Prestwich.</td>
+</tr><tr><td class="right" valign="top">(8)</td>
+ <td>'Structure and Probable Age of the Bagshot
+  Sands'&mdash;Ibid., vol. iii. Prestwich.</td>
+</tr><tr><td class="right" valign="top">(9)</td>
+ <td>'Tertiary Formations of the Isle of Wight'&mdash;Ibid.,
+  vol. ii. Prestwich.</td>
+</tr><tr><td class="right" valign="top">(10)</td>
+ <td>'Structure of the Strata between the London Clay and the
+  Chalk,' &amp;c.&mdash;Ibid., vols. vi., viii., and x.
+  Prestwich.</td>
+</tr><tr><td class="right" valign="top">(11)</td>
+ <td>'Correlation of the Eocene Tertiaries of England, France,
+  and Belgium'&mdash;Ibid., vol. xxvii. Prestwich.</td>
+</tr><tr><td class="right" valign="top">(12)</td>
+ <td>'On the Fluvio-marine Formations of the Isle of
+  Wight'&mdash;Ibid., vol. ix. Edward Forbes.</td>
+</tr><tr><td class="right" valign="top">(13)</td>
+ <td>'Newer Tertiary Deposits of the Sussex Coast'&mdash;Ibid.,
+  vol. xiii. Godwin-Austen.</td>
+</tr><tr><td class="right" valign="top">(14)</td>
+ <td>'Kainozoic Formations of Belgium'&mdash;Ibid., vol. xxii.
+  Godwin-Austen.</td>
+</tr><tr><td class="right" valign="top">(15)</td>
+ <td>'Tertiary Strata of Belgium and French
+  Flanders'&mdash;Ibid., vol. viii. Lyell.</td>
+</tr><tr><td class="right" valign="top">(16)</td>
+ <td>'On Tertiary Leaf-beds in the Isle of Mull'&mdash;Ibid.,
+  vol. vii. The Duke of Argyll.</td>
+</tr><tr><td class="right" valign="top">(17)</td>
+ <td>'Newer Tertiaries of Suffolk and their Fauna'&mdash;Ibid.,
+  vol. xxvi. Ray Lankester.</td>
+</tr><tr><td class="right" valign="top">(18)</td>
+ <td>'Lower London Tertiaries of Kent'&mdash;Ibid., vol. xxii.
+  Whitaker.</td>
+</tr><tr><td class="right" valign="top">(19)</td>
+ <td>"Guide to the Geology of London"&mdash;'Mem. Geol. Survey.'
+  Whitaker.</td>
+</tr><tr><td class="right" valign="top">(20)</td>
+ <td>'Memoirs of the Geological Survey of Great Britain.'</td>
+</tr><tr><td class="right" valign="top">(21)</td>
+ <td>'Introductory Outline of the Geology of the Crag District'
+  (Supplement to Crag Mollusca, Palæontographical
+  Society). S. V. Wood, jun., and F. w. Harmer.</td>
+</tr><tr><td class="right" valign="top">(22)</td>
+ <td>"Tertiary Fluvio-marine Deposits of the Isle of Wight."
+  Edward Forbes. Edited by Godwin-Austen; with Descriptions of
+  the Fossils by Morris, Salter, and Rupert Jones&mdash;'Memoirs
+  of the Geological Survey.'</td>
+</tr><tr><td class="right" valign="top">(23)</td>
+ <td>'Geological Excursions round the Isle of Wight.'
+  Mantell.</td>
+</tr><tr><td class="right" valign="top">(24)</td>
+ <td>'Catalogue of British Fossils.' Morris.</td>
+</tr><tr><td class="right" valign="top">(25)</td>
+ <td>'Catalogue of Fossils in the Museum of Practical Geology.'
+  Etheridge.</td>
+</tr><tr><td class="right" valign="top">(26)</td>
+ <td>'Monograph of the Crag Polyzoa' (Palæontographical
+  Society). Busk.</td>
+</tr><tr><td class="right" valign="top">(27)</td>
+ <td>'Monograph of the Tertiary Brachiopoda' (Ibid.)
+  Davidson.</td>
+</tr><tr><td class="right" valign="top">(28)</td>
+ <td>'Monograph of the Tertiary Malacostracous Crustacea'
+  (Ibid.) Bell.</td>
+</tr><tr><td class="right" valign="top">
+<a name="page_333"><span class="page">Page 333</span></a>
+  (29)</td>
+ <td>'Monograph of the Tertiary Corals' (Ibid.) Milne-Edwards
+  and Haime.</td>
+</tr><tr><td class="right" valign="top">(30)</td>
+ <td>'Supplement to the Tertiary Corals' (Ibid.) Martin
+  Duncan.</td>
+</tr><tr><td class="right" valign="top">(31)</td>
+ <td>'Monograph of the Eocene Mollusca' (Ibid.) Fred. E.
+  Edwards.</td>
+</tr><tr><td class="right" valign="top">(32)</td>
+ <td>'Monograph of the Eocene Mollusca' (Ibid.) Searles V.
+  Wood.</td>
+</tr><tr><td class="right" valign="top">(33)</td>
+ <td>'Monograph of the Crag Mollusca' (Ibid.) Searles V.
+  Wood.</td>
+</tr><tr><td class="right" valign="top">(34)</td>
+ <td>'Monograph of the Tertiary Entomostraca' (Ibid.) Rupert
+  Jones.</td>
+</tr><tr><td class="right" valign="top">(35)</td>
+ <td>'Monograph of the Foraminifera of the Crag' (Ibid.) Rupert
+  Jones, Parker, and H. B. Brady.</td>
+</tr><tr><td class="right" valign="top">(36)</td>
+ <td>'Monograph of the Radiaria of the London Clay' (Ibid.)
+  Edward Forbes.</td>
+</tr><tr><td class="right" valign="top">(37)</td>
+ <td>'Monograph of the Cetacea of the Red Crag' (Ibid.)
+  Owen.</td>
+</tr><tr><td class="right" valign="top">(38)</td>
+ <td>'Monograph of the Fossil Reptiles of the London Clay'
+  (Ibid.) Owen and Bell.</td>
+</tr><tr><td class="right" valign="top">(39)</td>
+ <td>"On the Skull of a Dentigerous Bird from the London Clay
+  of Sheppey"&mdash;'Quart. Journ. Geol. Soc.,' vol. xxix.
+  Owen.</td>
+</tr><tr><td class="right" valign="top">(40)</td>
+ <td>'Ossemens Fossiles.' Cuvier.</td>
+</tr><tr><td class="right" valign="top">(41)</td>
+ <td>'Fauna Antiqua Sivalensis.' Falconer and Sir Proby
+  Cautley.</td>
+</tr><tr><td class="right" valign="top">(42)</td>
+ <td>'Palæontological Memoirs.' Falconer.</td>
+</tr><tr><td class="right" valign="top">(43)</td>
+ <td>'Animaux Fossiles et Géologie de l'Attique.'
+  Gaudry.</td>
+</tr><tr><td class="right" valign="top">(44)</td>
+ <td>"Principal Characters of the Dinocerata"&mdash;'American
+  Journ. of Science and Arts,' vol. xi. Marsh.</td>
+</tr><tr><td class="right" valign="top">(45)</td>
+ <td>'Principal Characters of the Brontotheridæ' (Ibid.)
+  Marsh.</td>
+</tr><tr><td class="right" valign="top">(46)</td>
+ <td>'Principal Characters of the Tillodontia' (Ibid.)
+  Marsh.</td>
+</tr><tr><td class="right" valign="top">(47)</td>
+ <td>"Extinct Vertebrata of the Eocene of
+  Wyoming"&mdash;'Geological Survey of Montana,' &amp;c.,
+  1872. Cope.</td>
+</tr><tr><td class="right" valign="top">(48)</td>
+ <td>"Ancient Fauna of Nebraska"&mdash;'Smithsonian
+  Contributions to Knowledge,' vol. vi. Leidy.</td>
+</tr><tr><td class="right" valign="top">(49)</td>
+ <td>'Manual of Geology.' Dana.</td>
+</tr><tr><td class="right" valign="top">(50)</td>
+ <td>"Palæontology and Evolution" (Presidential Address
+  to the Geological Society of London, 1870)&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. xxvi. Huxley.'</td>
+</tr><tr><td class="right" valign="top">(51)</td>
+ <td>'Mineral Conchology.' Sowerby.</td>
+</tr><tr><td class="right" valign="top">(52)</td>
+ <td>'Description des Coquilles Fossiles,' &amp;c.
+  Deshayes.</td>
+</tr><tr><td class="right" valign="top">(53)</td>
+ <td>'Description des Coquilles Tertiaires de Belgique.'
+  Nyst.</td>
+</tr><tr><td class="right" valign="top">(54)</td>
+ <td>'Fossilen Polypen des Wiener Terti&auml;r-beckens.'
+  Reuss.</td>
+</tr><tr><td class="right" valign="top">(55)</td>
+ <td>'Palæontologische Studien &uuml;ber die &auml;lteren
+  Terti&auml;r-schichten der Alpen.' Reuss.</td>
+</tr><tr><td class="right" valign="top">(56)</td>
+ <td>'Land und S&uuml;ss-wasser Conchylien der Vorwelt.'
+  Sandberger.</td>
+</tr><tr><td class="right" valign="top">(57)</td>
+ <td>'Flora Tertiaria Helvetica.' Heer.</td>
+</tr><tr><td class="right" valign="top">(58)</td>
+ <td>'Flora Fossilis Arctica.' Heer.</td>
+</tr><tr><td class="right" valign="top">(59)</td>
+ <td>'Recherches sur le Climat et la Végétation
+  du Pays Tertiaire.' Heer.</td>
+</tr><tr><td class="right" valign="top">(60)</td>
+ <td>'Fossil Flora of Great Britain.' Lindley and Hutton.</td>
+</tr><tr><td class="right" valign="top">(61)</td>
+ <td>'Fossil Fruits and Seeds of the London Clay.'
+  Bowerbank.</td>
+</tr><tr><td class="right" valign="top">(62)</td>
+ <td>"Tertiary Leaf-beds of the Isle of Mull"&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. vii. Edward Forbes.</td>
+</tr><tr><td class="right" valign="top">(63)</td>
+ <td>'The Geology of England and Wales.' Horace B.
+  Woodward.[25]</td></tr>
+</table>
+
+<p class="footnote">
+[Footnote 25: This work&mdash;published whilst these sheets were
+going through the press&mdash;gives to the student a detailed
+view of all the strata of England and Wales, with their various
+sub-divisions, from the base of the Palæozoic to the top
+of the Tertiary.]
+</p>
+
+<h3>
+<a name="page_334"><span class="page">Page 334</span></a>
+CHAPTER XXI.</h3>
+
+<p class="subtitle">
+THE QUATERNARY PERIOD.
+</p>
+
+<p class="center">
+THE POST-PLIOCENE PERIOD.
+</p>
+
+<p class="indent">
+Later than any of the Tertiary formations are various detached and
+more or less superficial accumulations, which are generally spoken
+of as the <i>Post-Tertiary formations</i>, in accordance with the
+nomenclature of Sir Charles Lyell&mdash;or as the <i>Quaternary
+formations</i>, in accordance with the general usage of Continental
+geologists. In all these formations we meet with no <i>Mollusca</i>
+except such as are now alive&mdash;with the partial and very limited
+exception of some of the oldest deposits of this period, in which
+a few of the shells occasionally belong to species not known to
+be in existence at the present day. Whilst the <i>Shell-fish</i>
+of the Quaternary deposits are, generally speaking, identical
+with existing forms, the <i>Mammals</i> are sometimes referable
+to living, sometimes to extinct species. In accordance with this,
+the Quaternary formations are divided into two groups: (1) The
+<i>Post-Pliocene</i>, in which the shells are almost invariably
+referable to existing species, but some of the <i>Mammals are
+extinct</i>; and (2) the <i>Recent</i>, in which <i>the shells
+and the Mammals alike belong to existing species</i>. The
+Post-Pliocene deposits are often spoken of as the Pleistocene
+formations (Gr. <i>pleistos</i>, most; <i>kainos</i>, new or
+recent), in allusion to the fact that the great majority of the
+living beings of this period belong to the species characteristic
+of the "new" or Recent period.
+</p>
+
+<p class="indent">
+The <i>Recent</i> deposits, though of the highest possible interest,
+do not properly concern the palæontologist strictly so-called,
+but the zoologist, since they contain the remains of none but
+existing animals. They are "Pre-historic," but they belong entirely
+to the existing terrestrial order. The <i>Post-Pliocene</i> deposits,
+on the other hand, contain the remains of various extinct Mammals;
+and though Man undoubtedly existed in, at any rate, the later
+portion of this period, if not throughout the whole of it, they
+properly form part of the domain of the palæontologist.
+</p>
+
+<p class="indent">
+The Post-Pliocene deposits are extremely varied, and very widely
+distributed; and owing to the mode of their occurrence, the ordinary
+geological tests of age are in their case but very partially
+available. The subject of the classification of these deposits
+<a name="page_335"><span class="page">Page 335</span></a>
+is therefore an extremely complicated one;
+and as regards the age of even some of the most important of them,
+there still exists considerable difference of opinion. For our
+present purpose, it will be convenient to adopt a classification
+of the Post-Pliocene deposits founded on the relations which they
+bear in time to the great "Ice-age" or "Glacial period;" though
+it is not pretended that our present knowledge is sufficient to
+render such a classification more than a provisional one.
+</p>
+
+<p class="indent">
+In the early Tertiary period, as we have seen, the climate of the
+northern hemisphere, as shown by the Eocene animals and plants, was
+very much hotter than it is at present&mdash;partaking, indeed, of
+a sub-tropical character. In the Middle Tertiary or Miocene period,
+the temperature, though not so high, was still much warmer than
+that now enjoyed by the northern hemisphere; and we know that the
+plants of temperate regions at this time flourished within the
+Arctic circle. In the later Tertiary or Pliocene period, again,
+there is evidence that the northern hemisphere underwent a further
+progressive diminution of temperature; though the climate of Europe
+generally seems at the close of the Tertiary period to have been
+if anything warmer, or at any rate not colder, than it is at
+the present day. With the commencement of the Quaternary period,
+however, this diminution of temperature became more decided; and
+beginning with a temperate climate, we find the greater portion
+of the northern hemisphere to become gradually subjected to all
+the rigours of intense Arctic cold. All the mountainous regions
+of Northern and Central Europe, of Britain, and of North America,
+became the nurseries of huge ice-streams, and large areas of the
+land appear to have been covered with a continuous ice-sheet.
+The Arctic conditions of this, the well-known "Glacial period,"
+relaxed more than once, and were more than once re-established
+with lesser intensity. Finally, a gradual but steadily progressive
+amelioration of temperature took place; the ice slowly gave way,
+and ultimately disappeared altogether; and the climate once more
+became temperate, except in high northern latitudes.
+</p>
+
+<p class="indent">
+The changes of temperature sketched out above took place slowly
+and gradually, and occupied the whole of the Post-Pliocene period.
+In each of the three periods marked out by these changes&mdash;in
+the early temperate, the central cold, and the later temperate
+period&mdash;certain deposits were laid down over the surface of
+the northern hemisphere; and these deposits collectively constitute
+the Post-Pliocene formations. Hence we may conveniently classify
+all the accumulations of
+<a name="page_336"><span class="page">Page 336</span></a>
+this age under the
+heads of (1) <i>Pre-Glacial</i> deposits, (2) <i>Glacial</i>
+deposits, and (3) <i>Post-Glacial</i> deposits, according as they
+were formed before, during, or after the "Glacial period." It cannot
+by any means be asserted that we can definitely fix the precise
+relations in time of all the Post-Pliocene deposits to the Glacial
+period. On the contrary, there are some which hold a very disputed
+position as regards this point; and there are others which do not
+admit of definite allocation in this manner at all, in consequence
+of their occurrence in regions where no "Glacial Period" is known
+to have been established. For our present purpose, however, dealing
+as we shall have to do principally with the northern hemisphere,
+the above classification, with all its defects, has greater
+advantages than any other that has been yet proposed.
+</p>
+
+<p class="indent">
+I. PRE-GLACIAL DEPOSITS.&mdash;The chief pre-glacial deposit of
+Britain is found on the Norfolk coast, reposing upon the Newer
+Pliocene (Norwich Crag), and consists of an ancient land-surface
+which is known as the "Cromer Forest-bed."
+</p>
+
+<p class="indent">
+This consists of an ancient soil, having embedded in it the stumps
+of many trees, still in an erect position, with remains of living
+plants, and the bones of recent and extinct quadrupeds. It is
+overlaid by fresh-water and marine beds, all the shells of which
+belong to existing species, and it is finally surmounted by true
+"glacial drift." While all the shells and plants of the Cromer
+Forest-bed and its associated strata belong to existing species,
+the Mammals are partly living, partly extinct. Thus we find the
+existing Wolf (<i>Canis lupus</i>), Red Deer (<i>Cervus elaphus</i>),
+Roebuck (<i>Cervus capreolus</i>), Mole (<i>Talpa Europtœa</i>),
+and Beaver (<i>Castor fiber</i>), living in western England side
+by side with the <i>Hippopotamus major, Elephas antiquus, Elephas
+meridionalis, Rhinoceros Etruscus</i>, and <i>R. Megarhinus</i>
+of the Pliocene period, which are not only extinct, but imply
+an at any rate moderately warm climate. Besides the above, the
+Forest-bed has yielded the remains of several extinct species of
+Deer, of the great extinct Beaver (<i>Trogontherium Cuvieri</i>),
+of the Caledonian Bull or "Urus" (<i>Bos primigenius</i>), and of
+a Horse (<i>Equus fossilis</i>), little if at all distinguishable
+from the existing form.
+</p>
+
+<p class="indent">
+The so-called "Bridlington Crag" of Yorkshire, and the "Chillesford
+Beds" of Suffolk, are probably to be regarded as also belonging
+to this period; though many of the shells which they contain
+are of an Arctic character, and would indicate that they were
+deposited in the commencement of the Glacial period itself. Owing,
+however, to the fact that a few of the shells of these deposits
+are not known to occur in a living
+<a name="page_337"><span class="page">Page 337</span></a>
+condition, these, and some other similar accumulations, are
+sometimes considered as referable to the Pliocene period.
+</p>
+
+<p class="indent">
+II. GLACIAL DEPOSITS.&mdash;Under this head is included a great
+series of deposits which are widely spread over both Europe and
+America, and which were formed at a time when the climate of
+these countries was very much colder than it is at present, and
+approached more or less closely to what we see at the present
+day in the Arctic regions. These deposits are known by the
+general name of the <i>Glacial deposits</i>, or by the more
+specialised names of the Drift, the Northern Drift, the
+Boulder-clay, the Till, &amp;c.
+</p>
+
+<p class="indent">
+These glacial deposits are found in Britain as far south as the
+Thames, over the whole of Northern Europe, in all the more elevated
+portions of Southern and Central Europe, and over the whole of
+North America, as far south as the 39th parallel. They generally
+occur as sands, clays, and gravels, spread in widely-extended
+sheets over all the geological formations alike, except the most
+recent, and are commonly spoken of under the general term of
+"Glacial drift." They vary much in their exact nature in different
+districts, but they universally consist of one, or all, of the
+following members:&mdash;
+</p>
+
+<p class="indent">
+1. <i>Unstratified</i> clays, or loams, containing numerous angular
+or sub-angular blocks of stone, which have often been transported
+for a greater or less distance from their parent rock, and which
+often exhibit polished, grooved, or striated surfaces. These
+beds are what is called <i>Boulder-clay</i>, or <i>Till</i>.
+</p>
+
+<p class="indent">
+2. Sands, gravels, and clays, often more or less regularly
+<i>stratified</i>, but containing erratic blocks, often of large
+size, and with their edges <i>unworn</i>, derived from considerable
+distances from the place where they are now found. In these beds it
+is not at all uncommon to find fossil shells; and these, though of
+existing species, are generally of an Arctic character, comprising
+a greater or less number of forms which are now exclusively found
+in the icy waters of the Arctic seas. These beds are often spoken
+of as "Stratified Drift."
+</p>
+
+<p class="indent">
+3. <i>Stratified</i> sands and gravels, in which the pebbles
+are <i>worn</i> and rounded, and which have been produced by a
+rearrangement of ordinary glacial beds by the sea. These beds
+are commonly known as "Drift-gravels," or "Regenerated Drift".
+</p>
+
+<p class="indent">
+Some of the last-mentioned of these are doubtless post-glacial;
+but, in the absence of fossils, it is often impossible to arrive at
+a positive opinion as to the precise age of superficial accumulations
+of this nature. It is also the opinion of high authorities that
+a considerable number of the so-called "cave-deposits,"
+<a name="page_338"><span class="page">Page 338</span></a>
+with the bones of extinct Mammals, truly belong
+to the Glacial period, being formed during warm intervals when
+the severity of the Arctic cold had become relaxed. It is further
+believed that some, at any rate, of the so-called "high-level"
+river-gravels and "brick-earths" have likewise been deposited during
+mild or warm intervals in the great age of ice; and in two or three
+instances this has apparently been demonstrated&mdash;deposits of
+this nature, with the bones of extinct animals and the implements
+of man, having been shown to be overlaid by true Boulder-clay.
+</p>
+
+<p class="indent">
+The fossils of the undoubted Glacial deposits are principally
+shells, which are found in great numbers in certain localities,
+sometimes with <i>Foraminifera</i>, the bivalved cases of Ostracode
+Crustaceans, &amp;c. Whilst some of the shells of the "Drift" are
+such as now live in the seas of temperate regions, others, as
+previously remarked, are such as are now only known to live in the
+seas of high latitudes; and these therefore afford unquestionable
+evidence of cold conditions. Amongst these Arctic forms of shells
+which characterise the Glacial beds may be mentioned <i>Pecten
+Islandicus</i> (fig. 254),
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 345px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig254.jpg" width="345" height="370" alt="Fig. 254" />
+<br />
+Fig. 254.&mdash;Left valve of <i>Pecten Islandicus</i>, Glacial
+and Recent.
+</span>
+</span>
+
+<i>Pecten Grœnlandicus, Scalaria Grœnlandica, Leda
+truncata, Astarte borealis, Tellina proxima, Nattra clausa</i>,
+&amp;c.
+</p>
+
+<p class="indent">
+III. POST-GLACIAL DEPOSITS.&mdash;As the intense cold of the
+Glacial period became gradually mitigated, and temperate
+<a name="page_339"><span class="page">Page 339</span></a>
+conditions of climate were once more
+re-established, various deposits were formed in the northern
+hemisphere, which are found to contain the remains of extinct
+Mammals, and which, therefore, are clearly of Post-Pliocene
+age. To these deposits the general name of <i>Post-Glacial</i>
+formations is given; but it is obvious that, from the nature
+of the case, and with our present limited knowledge, we cannot
+draw a rigid line of demarcation between the deposits formed
+towards the close of the Glacial period, or during warm
+"interglacial" periods, and those laid down after the ice had
+fairly disappeared. Indeed it is extremely improbable that any
+such rigid line of demarcation should ever have existed; and it
+is far more likely that the Glacial and Post-Glacial periods,
+and their corresponding deposits, shade into one another by an
+imperceptible gradation. Accepting this reservation, we may group
+together, under the general head of "Post-Glacial Deposits,"
+most of the so-called "Valley-gravels," "Brick-earths," and
+"Cave-deposits," together with some "raised beaches" and various
+deposits of peat. Though not strictly within the compass of this
+work, a few words may be said here as to the origin and mode of
+formation of the Brick-earths, Valley-gravels, and Cave-deposits,
+as the subject will thus be rendered more clearly intelligible.
+</p>
+
+<p class="indent">
+Every river produces at the present day beds of fine mud and
+loam, and accumulations of gravel, which it deposits at various
+parts of its course&mdash;the gravel generally occupying the
+lowest position, and the finer sands and mud coming above. Numerous
+deposits of a similar nature are found in most countries in various
+localities, and at various heights above the present channels of
+our rivers. Many of these fluviatile (Lat. <i>fluvius</i>, a
+river) deposits consist of fine loam, worked for brick-making,
+and known as "Brick-earths;" and they have yielded the remains
+of numerous extinct Mammals, of which the Mammoth (<i>Elephas
+primigenius</i>) is the most abundant. In the valley of the Rhine
+these fluviatile loams (known as "Loess") attain a thickness of
+several hundred feet, and contain land and fresh-water shells of
+existing species. With these occur the remains of Mammals, such
+as the Mammoth and Woolly Rhinoceros. Many of these Brick-earths
+are undoubtedly Post-Glacial, but others seem to be clearly
+"inter-glacial;" and instances have recently been brought forward
+in which deposits of Brick-earth containing bones and shells of
+fresh-water Molluscs have been found to be overlaid by regular
+unstratified boulder-clay.
+</p>
+
+<p class="indent">
+The so-called "Valley-gravels," like the Brick-earths, are
+<a name="page_340"><span class="page">Page 340</span></a>
+fluviatile deposits, but are of a coarser nature, consisting of
+sands and gravels. Every river gives origin to deposits of this kind
+at different points along the course of its valley; and it is not
+uncommon to find that there exist in the valley of a single river
+two or more sets of these gravel-beds, formed by the river itself,
+but formed at times when the river ran at different levels, and
+therefore formed at different periods. These different accumulations
+are known as the "high-level" and "low-level" gravels; and
+a reference to the accompanying diagram will explain the origin
+and nature of these deposits (fig. 255). When a river begins
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 556px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig255.jpg" width="556" height="184" alt="Fig. 255" />
+<br />
+Fig. 255.&mdash;Recent and Post-Pliocene Alluvial Deposits. 1,
+Peat of the recent period; 2, Gravel of the modern river: 2',
+Loam of the modern river; 3. Lower-level valley-gravel with
+bones of extinct Mammals (Post-Pliocene); 3', Loam of the same
+age as 3; 4. Higher-level valley-gravel (Post-Pliocene); 4',
+Loam of the same age as 4; 5. Upland gravels of various kinds
+(often glacial drift); 6, Older rock. (After Sir Charles Lyell.)
+</span>
+</span>
+
+to occupy a particular line of drainage, and to form its own
+channel, it will deposit fluviatile sands and gravels along its
+sides. As it goes on deepening the bed or valley through which
+it flows, it will deposit other fluviatile strata at a lower
+level beside its new bed. In this way have arisen the terms
+"high-level" and "low-level" gravels. We find, for instance, a
+modern river flowing through a valley which it has to a great
+extent or entirely formed itself; by the side of its immediate
+channel we may find gravels, sand, and loam (fig. 255, 2 2')
+deposited by the river flowing in its present bed. These are
+<i>recent</i> fluviatile or alluvial deposits. At some distance
+from the present bed of the river, and at a higher level, we
+may find other sands and gravels, quite like the recent ones
+in character and origin, but formed at a time when the stream
+flowed at a higher level, and before it had excavated its valley
+to its present depth. These (fig. 255, 3 3') are the so-called
+"<i>low-level</i> gravels" of a river. At a still higher level,
+and still farther removed from the present bed of the river, we
+may find another terrace, composed of just the same materials
+as the lower one, but formed at a still earlier period, when the
+<a name="page_341"><span class="page">Page 341</span></a>
+excavation of the valley had proceeded to a much less extent.
+These (fig. 255, 4 4') are the so-called "<i>high-level</i>
+gravels" of a river, and there may be one or more terraces of these.
+</p>
+
+<p class="indent">
+The important fact to remember about these fluviatile deposits is
+this&mdash;that here the ordinary geological rule is reversed. The
+high-level gravels are, of course, the highest, so far as their
+actual elevation above the sea is concerned; but geologically the
+lowest, since they are obviously much older than the low-level
+gravels, as these are than the recent gravels. How much older
+the high-level gravels may be than the low-level ones, it is
+impossible to say. They occur at heights varying from 10 to 100
+feet above the present river-channels, and they are therefore
+older than the recent gravels by the time required by the river
+to dig out its own bed to this depth. How long this period may
+be, our data do not enable us to determine accurately; but if
+we are to calculate from the observed rate of erosion of the
+actually existing rivers, the period between the different
+valley-gravels must be a very long one.
+</p>
+
+<p class="indent">
+The lowest or recent fluviatile deposits which occur beside the
+bed of the present river, are referable to the Recent period,
+as they contain the remains of none but living Mammals. The two
+other sets of gravels are Post-Pliocene, as they contain the
+bones of extinct Mammals, mixed with land and fresh-water shells
+of existing species. Among the more important extinct Mammals of
+the low-level and high-level valley-gravels may be mentioned the
+<i>Elephas antiquus</i>, the Mammoth (<i>Elephas primigenius</i>),
+the Woolly Rhinoceros (<i>R. Tichorhinus</i>), the Hippopotamus,
+the Cave-lion, and the Cave-bear. Along with these are found
+unquestionable traces of the existence of Man, in the form of
+rude flint implements of undoubted human workmanship.
+</p>
+
+<p class="indent">
+The so-called "Cave-deposits," again, though exhibiting
+peculiarities due to the fact of their occurrence in caverns
+or fissures in the rocks, are in many respects essentially
+similar to the older valley-gravels. Caves, in the great
+majority of instances, occur in limestone. When this is not
+the case, it will generally be found that they occur along
+lines of sea-coast, or along lines which can be shown to have
+anciently formed the coast-line. There are many caves, however,
+in the making of which it can be shown that the sea has had no
+hand; and these are most of the caves of limestone districts.
+These owe their origin to the solvent action upon lime of water
+holding carbonic acid in solution. The rain which falls upon a
+limestone district absorbs a certain amount of carbonic acid from
+<a name="page_342"><span class="page">Page 342</span></a>
+the air, or from the soil. It then
+percolates through the rock, generally along the lines of jointing
+so characteristic of limestones, and in its progress it dissolves
+and carries off a certain quantity of carbonate of lime. In this
+way, the natural joints and fissures in the rock are widened, as
+can be seen at the present day in any or all limestone districts.
+By a continuance of this action for a sufficient length of time,
+caves may ultimately be produced. Nothing, also, is commoner in
+a limestone district than for the natural drainage to take the
+line of some fissure, dissolving the rock in its course. In this
+way we constantly meet in limestone districts with springs issuing
+from the limestone rock&mdash;sometimes as large rivers&mdash;the
+waters of which are charged with carbonate of lime, obtained by
+the solution of the sides of the fissure through which the waters
+have flowed. By these and similar actions, every district in which
+limestones are extensively developed will be found to exhibit
+a number of natural caves, rents, or fissures. The first element,
+therefore, in the production of cave-deposits, is the existence
+of a period in which limestone rocks were largely dissolved, and
+caves were formed in consequence of the then existing drainage
+taking the line of some fissure.
+</p>
+
+<p class="indent">
+Secondly, there must have been a period in which various deposits
+were accumulated in the caves thus formed. These cavern-deposits
+are of very various nature, consisting of mud, loam, gravel,
+or breccias of different kinds. In all cases, these materials
+have been introduced into the cave at some period subsequent to,
+or contemporaneous with, the formation of the cave. Sometimes
+the cave communicates with the surface by a fissure through which
+sand, gravel, &amp;c., may be washed by rains or by floods from
+some neighbouring river. Sometimes the cave has been the bed of an
+ancient stream, and the deposits have been formed as are fluviatile
+deposits at the surface. Or, again, the river has formerly flowed
+at a greater elevation than it does at present, and the cave
+has been filled with fluviatile deposits by the river at a time
+prior to the excavation of its bed to the present depth (fig.
+256). In this last case, the cave-deposits obviously bear exactly
+the same relation in point of antiquity to recent deposits, as
+do the low-level and high-level valley-gravels to recent
+river-gravels. In any case, it is necessary for the physical
+geography of the district to change to some extent, in order
+that the cave-deposits should be preserved. If the materials
+have been introduced by a fissure, the cave will probably become
+ultimately filled to the roof, and the aperture of admission
+thus blocked up. If a river has flowed through the cave, the
+surface configuration
+<a name="page_343"><span class="page">Page 343</span></a>
+of the district must be altered so far as to divert the river
+into a new channel. And if the cave is placed in the side of
+a river-valley, as in fig. 256, the river must have excavated
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 571px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig256.jpg" width="571" height="163" alt="Fig. 256" />
+<br />
+Fig. 256.&mdash;Diagrammatic section across a river-valley and
+cave. <i>a a</i>, Recent valley-gravels near the channel
+(<i>b</i>) of the existing river; <i>c</i>, Cavern, partly filled
+with cave-earth; <i>d d</i>, High-level gravels, filling fissures
+in the limestone, which perhaps communicate in some instances
+with the cave, and form a channel by which materials of various
+kinds were introduced into it; <i>e e</i>, Inclined beds of
+limestone.
+</span>
+</span>
+
+its channel to such a depth that it can no longer wash out the
+contents of the cave even in high floods.
+</p>
+
+<p class="indent">
+If the cave be entirely filled, the included deposits generally
+get more or less completely cemented together by the percolation
+through them of water holding carbonate of lime in solution. If
+the cave is only partially filled, the dropping of water from
+the roof holding lime in solution, and its subsequent evaporation,
+would lead to the formation over the deposits below of a layer of
+stalagmite, perhaps several inches, or even feet, in thickness.
+In this way cave-deposits, with their contained remains, may
+be hermetically sealed up and preserved without injury for an
+altogether indefinite period of time.
+</p>
+
+<p class="indent">
+In all caves in limestone in which deposits containing bones are
+found, we have then evidence of three principal sets of changes.
+(1.) A period during which the cave was slowly hollowed out by
+the percolation of acidulated water; (2.) A period in which the
+cave became the channel of an engulfed river, or otherwise came
+to form part of the general drainage-system of the district; (3.)
+A period in which the cave was inhabited by various animals.
+</p>
+
+<p class="indent">
+As a typical example of a cave with fossiliferous Post-Pliocene
+deposits, we may take Kent's Cavern, near Torquay, in which a
+systematic and careful examination has revealed the following
+sequence of accumulations in descending order:&mdash;
+</p>
+
+<p class="indent">
+(<i>a</i>) Large blocks of limestone, which lie on the floor of
+the cave, having fallen from the roof, and which are sometimes
+cemented together by stalagmite.
+</p>
+
+<p class="indent">
+(<i>b</i>) A layer of black mould, from three to twelve inches
+thick, with human bones, fragments of pottery, stone and
+<a name="page_344"><span class="page">Page 344</span></a>
+bronze implements, and the bones of animals now living in Britain.
+This, therefore, is a <i>recent</i> deposit.
+</p>
+
+<p class="indent">
+(<i>c</i>) A layer of stalagmite, from sixteen to twenty inches
+thick, but sometimes as much as five feet, containing the bones
+of Man, together with those of extinct Post-Pliocene Mammals.
+</p>
+
+<p class="indent">
+(<i>d</i>) A bed of red cave-earth, sometimes four feet in thickness,
+with numerous bones of extinct Mammals (Mammoth, Cave-bear, &amp;c.),
+together with human implements of flint and horn.
+</p>
+
+<p class="indent">
+(<i>e</i>) A second bed of stalagmite, in places twelve feet in
+thickness, with bones of the Cave-bear.
+</p>
+
+<p class="indent">
+(<i>f</i>) A red-loam and cave-breccia, with remains of the Cave-bear
+and human implements.
+</p>
+
+<p class="indent">
+The most important Mammals which are found in cave-deposits in
+Europe generally, are the Cave-bear, the Cave-lion, the Cave-hyæna,
+the Reindeer, the Musk-ox, the Glutton, and the Lemming&mdash;of which
+the first three are probably identical with existing forms, and
+the remainder are certainly so&mdash;together with the Mammoth and
+the Woolly Rhinoceros, which are undoubtedly extinct. Along with
+these are found the implements, and in some cases the bones, of
+Man himself, in such a manner as to render it absolutely certain
+that an early race of men was truly contemporaneous in Western
+Europe with the animals above mentioned.
+</p>
+
+<p class="indent">
+IV. UNCLASSIFIED POST-PLIOCENE DEPOSITS.&mdash;Apart from any
+of the afore mentioned deposits, there occur other
+accumulations&mdash;sometimes superficial, sometimes in
+caves&mdash;which are found in regions where a "Glacial period"
+has not been fully demonstrated, or where such did not take
+place; and which, therefore, are not amenable to the above
+classification. The most important of these are known to occur
+in South America and Australia; and though their numerous
+extinct Mammalia place their reference to the Post-Pliocene
+period beyond doubt, their relations to the glacial period and
+its deposits in the northern hemisphere have not been precisely
+determined.
+</p>
+
+<h3>CHAPTER XXII.</h3>
+
+<p class="subtitle">
+THE POST-PLIOCENE PERIOD&mdash;<i>Continued.</i>
+</p>
+
+<p class="indent">
+As regards the <i>life</i> of the Post-Pliocene period, we have,
+in the first place, to notice the effect produced throughout the
+<a name="page_345"><span class="page">Page 345</span></a>
+northern hemisphere by the gradual
+supervention of the Glacial period. Previous to this the climate
+must have been temperate or warm-temperate; but as the cold
+gradually came on, two results were produced as regards the
+living beings of the area thus affected. In the first place,
+all those Mammals which, like the Mammoth, the Woolly Rhinoceros,
+the Lion, the Hyæna, and the Hippopotamus, require, at
+any rate, moderately warm conditions, would be forced to
+migrate southwards to regions not affected by the new state
+of things. In the second place, Mammals previously inhabiting
+higher latitudes, such as the Reindeer, the Musk-ox, and the
+Lemming, would be enabled by the increasing cold to migrate
+southwards, and to invade provinces previously occupied by the
+Elephant and the Rhinoceros. A precisely similar, but more
+slowly-executed process, must have taken place in the sea, the
+northern Mollusca moving southwards as the arctic conditions of
+the Glacial period became established, whilst the forms proper
+to temperate seas receded. As regards the readily locomotive
+Mammals, also, it is probable that this process was carried on
+repeatedly in a partial manner, the southern and northern forms
+alternately fluctuating backwards and forwards over the same
+area, in accordance with the fluctuations of temperature which
+have been shown by Mr James Geikie to have characterised the
+Glacial period as a whole. We can thus readily account for the
+intermixture which is sometimes found of northern and southern
+types of Mammalia in the same deposits, or in deposits apparently
+synchronous, and within a single district. Lastly, at the final close
+of the arctic cold of the Glacial period, and the re-establishment
+of temperate conditions over the northern hemisphere, a reversal of
+the original process took place&mdash;the northern Mammals retiring
+within their ancient limits, and the southern forms pressing
+northwards and reoccupying their original domains.
+</p>
+
+<p class="indent">
+The <i>Invertebrate</i> animals of the Post-Pliocene deposits
+require no further mention&mdash;all the known forms, except a
+few of the shells in the lowest beds of the formation, being
+identical with species now in existence upon the globe. The
+only point of importance in this connection has been previously
+noticed&mdash;namely, that in the true Glacial deposits
+themselves a considerable number of the shells belong to
+northern or Arctic types.
+</p>
+
+<p class="indent">
+As regards the <i>Vertebrate</i> animals of the period, no extinct
+forms of Fishes, Amphibians, or Reptiles are known to occur, but we
+meet with both extinct Birds and extinct Mammals. The remains of
+the former are of great interest, as indicating
+<a name="page_346"><span class="page">Page 346</span></a>
+the existence during Post-Pliocene times, at widely remote
+points of the southern hemisphere, of various wingless, and for the
+most part gigantic, Birds. All the great wingless Birds of the order
+<i>Cursores</i> which are known as existing at the present day upon
+the globe, are restricted to regions which are either wholly or
+in great part south of the equator. Thus the true Ostriches are
+African; the Rheas are South American; the Emeus are Australian;
+the Cassowaries are confined to Northern Australia, Papua, and the
+Indian Archipelago; the species of <i>Apteryx</i> are natives of New
+Zealand; and the Dodo and Solitaire (wingless, though probably not
+true <i>Cursores</i>), both of which have been exterminated within
+historical times, were inhabitants of the islands of Mauritius
+and Rodriguez, in the Indian Ocean. In view of these facts, it
+is noteworthy that, so far as known, all the Cursorial Birds
+of the Post-Pliocene period should have been confined to the
+same hemisphere as that inhabited by the living representatives
+of the order. It is still further interesting to notice that
+the extinct forms in question are only found in geographical
+provinces which are now, or have been within historical times,
+inhabited by similar types. The greater number of the remains of
+these have been discovered in New Zealand, where there now live
+several species of the curious wingless genus <i>Apteryx</i>;
+and they have been referred by Professor Owen to several generic
+groups, of which <i>Dinornis</i> is the most important (fig.
+257). Fourteen species of <i>Dinornis</i> have been described by
+the distinguished palæontologist just mentioned, all of them
+being large wingless birds of the type of the existing Ostrich,
+having enormously powerful hind-limbs adapted for running, but
+with the wings wholly rudimentary, and the breast-bone devoid
+of the keel or ridge which characterises this bone in all birds
+which fly. The largest species is the <i>Dinornis giganteus</i>,
+one of the most gigantic of living or fossil birds, the shank
+(tibia) measuring a yard in length, and the total height being at
+least ten feet. Another species, the <i>Dinornis Elephantopus</i>
+(fig. 257), though not standing more than about six feet in height,
+was of an even more ponderous construction&mdash;"the framework of
+the skeleton being the most massive of any in the whole class of
+Birds," whilst "the toe-bones almost rival those of the Elephant"
+(Owen). The feet in <i>Dinornis</i> were furnished with three
+toes, and are of interest as presenting us with an undoubted
+Bird big enough to produce the largest of the foot-prints of
+the Triassic Sandstones of Connecticut. New Zealand has now been
+so far explored, that it seems questionable if it can retain in
+its recesses any living example of <i>Dinornis</i>; but it
+<a name="page_347"><span class="page">Page 347</span></a>
+is certain that species of this genus were alive during the human
+period, and survived up to quite a recent date. Not only are the
+bones very numerous in certain localities, but they are found in
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 383px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig257.jpg" width="383" height="585" alt="Fig. 257" />
+<br />
+Fig. 257.&mdash;Skeleton of <i>Dinornis elephantopus</i>, greatly
+reduced. Post-Pliocene, New Zealand. (After Owen.)
+</span>
+</span>
+
+the most recent and superficial deposits, and they still contain a
+considerable proportion of animal matter; whilst in some instances
+bones have been found with the feathers attached, or with the horny
+skin of the legs still adhering to them. Charred bones have been
+found in connection with native "ovens;" and the traditions of
+the Maories contain circumstantial accounts of gigantic wingless
+Birds, the "Moas," which were hunted both for their flesh and
+their plumage. Upon the whole, therefore, there can be no doubt
+<a name="page_348"><span class="page">Page 348</span></a>
+but that the Moas of New Zealand have been exterminated at quite
+a recent period&mdash;perhaps within the last century&mdash;by the
+unrelenting pursuit of Man,&mdash;a pursuit which their wingless
+condition rendered them unable to evade.
+</p>
+
+<p class="indent">
+In Madagascar, bones have been discovered of another huge wingless
+Bird, which must have been as large as, or larger than, the
+<i>Dinornis giganteus</i>, and which has been described under the
+name of <i>Æpiornis maximus</i>. With the bones have been found
+eggs measuring from thirteen to fourteen inches in diameter, and
+computed to have the capacity of three Ostrich eggs. At least two
+other smaller species of <i>Æpiornis</i> have been described by
+Grandidier and Milne-Edwards as occurring in Madagascar; and they
+consider the genus to be so closely allied to the <i>Dinornis</i>
+of New Zealand, as to prove that these regions, now so remote,
+were at one time united by land. Unlike New Zealand, where there
+is the <i>Apteryx</i>, Madagascar is not known to possess any
+living wingless Birds; but in the neighbouring island of Mauritius
+the wingless Dodo (<i>Didus ineptus</i>) has been exterminated
+less than three hundred years ago; and the little island of
+Rodriguez, in the same geographical province, has in a similar
+period lost the equally wingless Solitaire (<i>Pezophaps</i>), both
+of these, however, being generally referred to the <i>Rasores</i>.
+</p>
+
+<p class="indent">
+The <i>Mammals</i> of the Post-Pliocene period are so numerous,
+that in spite of the many points of interest which they present,
+only a few of the more important forms can be noticed here, and
+that but briefly. The first order that claims our attention is
+that of the <i>Marsupials</i>, the headquarters of which at the
+present day is the Australian province. In Oolitic times Europe
+possessed its small Marsupials, and similar forms existed in the
+same area in the Eocene and Miocene periods; but if size be any
+criterion, the culminating point in the history of the order was
+attained during the Post-Pliocene period in
+
+<span style="float: left; margin: 4px; width: 265px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig258.jpg" width="265" height="161" alt="Fig. 258" />
+<br />
+Fig. 258.&mdash;Skull of <i>Diprotodon Australis</i>, greatly
+reduced. Post-Pliocene, Australia.
+</span>
+
+Australia. From deposits of this age there has been disentombed
+a whole series of remains of extinct, and for the most part
+gigantic, examples of this group of Quadrupeds. Not to speak of
+Wombats and Phalangers, two forms stand out prominently as
+representatives of the Post-Pliocene animals of Australia. One
+of these is <i>Diprotodon</i> (fig. 258), representing, with
+many differences, the well-known modern group of the Kangaroos.
+<a name="page_349"><span class="page">Page 349</span></a>
+In its teeth, <i>Diprotodon</i> shows
+itself to be closely allied to the living, grass-eating Kangaroos;
+but the hind-limbs were not so disproportionately long. In size,
+also, <i>Diprotodon</i> must have many times exceeded the
+dimensions of the largest of its living successors, since the
+skull measures no less than three feet in length. The other form
+in question is <i>Thylacoleo</i> (fig. 259), which is believed by
+Professor Owen to belong to the same group as the existing "Native
+Devil" (<i>Dasyurus</i>) of Van Diemen's Land, and therefore to
+have been flesh-eating and rapacious in its habits, though this
+view is not accepted by others. The principal feature in the skull
+of <i>Thylacoleo</i> is the presence, on each side of each jaw,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 536px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig259.jpg" width="536" height="378" alt="Fig. 259" />
+<br />
+Fig. 259.&mdash;Skull of <i>Thylacoleo</i>. Post-Pliocene,
+Australia. Greatly reduced. (After Flower.)
+</span>
+</span>
+
+of a single huge tooth, which is greatly compressed, and has a
+cutting edge. This tooth is regarded by Owen as corresponding to
+the great cutting tooth of the jaw of the typical Carnivores,
+but Professor Flower considers that <i>Thylacoleo</i> is rather
+related to the Kangaroo-rats. The size of the crown of the tooth
+in question is not less than two inches and a quarter; and whether
+carnivorous or not, it indicates an animal of a size exceeding
+that of the largest of existing Lions.
+</p>
+
+<p class="indent">
+The order of the <i>Edentates</i>, comprising the existing Sloths,
+Ant-eaters, and Armadillos, and entirely restricted at the present
+day to South America, Southern Asia, and Africa, is one alike
+<a name="page_350"><span class="page">Page 350</span></a>
+singular for the limited geographical range
+of its members, their curious habits of life, and the well-marked
+peculiarities of their anatomical structure. South America is the
+metropolis of the existing forms; and it is an interesting fact
+that there flourished within Post-Pliocene times in this continent,
+and to some extent in North America also, a marvellous group of
+extinct Edentates, representing the living Sloths and Armadillos,
+but of gigantic size. The most celebrated of these is the huge
+<i>Megatherium Cuvieri</i> (fig. 260) of the South American Pampas.
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 543px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig260.jpg" width="543" height="301" alt="Fig. 260" />
+<br />
+Fig. 260.&mdash;<i>Megatherium Cuvieri</i>. Post-Pliocene, South
+America.
+</span>
+</span>
+
+The Megathere was a colossal Sloth-like animal which attained a
+length of from twelve to eighteen feet, with bones more massive
+than those of the Elephant. Thus the thigh-bone is nearly thrice
+the thickness of the same bone in the largest of existing Elephants,
+its circumference at its narrowest point nearly equalling its
+total length; the massive bones of the shank (tibia and fibula)
+are amalgamated at their extremities; the heel-bone (calcaneum)
+is nearly half a yard in length; the haunch-bones (ilia) are
+from four to five feet across at their crests; and the bodies of
+the vertebræ at the root of the tail are from five to seven
+inches in diameter, from which it has been computed that the
+circumference of the tail at this part might have been from five
+to six feet. The length of the fore-foot is about a yard, and
+the toes are armed with powerful curved claws. It is known now
+that the Megathere, in spite of its enormous weight and ponderous
+construction, walked, like the existing Ant-eaters and Sloths,
+upon the outside edge of the fore-feet, with the claws more or
+less bent inwards
+<a name="page_351"><span class="page">Page 351</span></a>
+towards the palm of the
+hand. As in the great majority of the Edentate order, incisor and
+canine teeth are entirely wanting, the front of the jaws being
+toothless. The jaws, however, are furnished with five upper and
+four lower molar teeth on each side. These grinding teeth are from
+seven to eight inches in length, in the form of four-sided prisms,
+the crowns of which are provided with well-marked transverse ridges;
+and they continue to grow during the whole life of the animal.
+There are indications that the snout was prolonged, and more or
+less flexible; and the tongue was probably prehensile. From the
+characters of the molar teeth it is certain that the Megathere was
+purely herbivorous in its habits; and from the enormous size and
+weight of the body, it is equally certain that it could not have
+imitated its modern allies, the Sloths, in the feat of climbing,
+back downwards, amongst the trees. It is clear, therefore, that
+the Megathere sought its sustenance upon the ground; and it was
+originally supposed to have lived upon roots. By a masterly piece
+of deductive reasoning, however, Professor Owen showed that this
+great "Ground-Sloth" must have truly lived upon the foliage of
+trees, like the existing Sloths&mdash;but with this difference,
+that instead of climbing amongst the branches, it actually
+uprooted the tree bodily. In this <i>tour de force</i>, the animal
+sat upon its huge haunches and mighty tail, as on a tripod, and
+then grasping the trunk with its powerful arms, either wrenched it
+up by the roots or broke it short off above the ground. Marvellous
+as this may seem, it can be shown that every detail in the skeleton
+of the Megathere accords with the supposition that it obtained
+its food in this way. Similar habits were followed by the allied
+<i>Mylodon</i> (fig. 261), another of the great "Ground-Sloths,"
+which inhabited South America during the Post-Pliocene period. In
+most respects, the <i>Mylodon</i> is very like the Megathere; but
+the crowns of the molar teeth are flat instead of being ridged.
+The nearly-related genus <i>Megalonyx</i>, unlike the Megathere,
+but like the Mylodon, extended its range northwards as far as
+the United States.
+</p>
+
+<p class="indent">
+Just as the Sloths of the present day were formerly represented
+in the same geographical area by the gigantic Megatheroids, so
+the little banded and cuirassed Armadillos of South America were
+formerly represented by gigantic species, constituting the genus
+<i>Glyptodon</i>. The <i>Glyptodons</i> (fig. 262) differed from
+the living Armadillos in having no bands in their armour, so that
+they must have been unable to roll themselves up. It is rare
+at the present day to meet with any
+<a name="page_352"><span class="page">Page 352</span></a>
+Armadillo over two or three feet in length; but the length of the
+<i>Glyptodon clavipes</i>, from the tip of the snout to the end
+of the tail, was more than nine feet.
+</p>
+
+<p class="indent">
+There are no canine or incisor teeth in the <i>Glyptodon</i>, but
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 382px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig261.jpg" width="382" height="434" alt="Fig. 261" />
+<br />
+Fig. 261.&mdash;Skeleton of <i>Mylodon robustus</i>. Post-Pliocene,
+South America.
+</span>
+</span>
+
+there are eight molars on each side of each jaw, and the crowns
+of these are fluted and almost trilobed. The head is covered
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 472px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig262.jpg" width="472" height="222" alt="Fig. 262" />
+<br />
+Fig. 262.&mdash;Skeleton of <i>Glyptodon clavipes</i>.
+Post-Pliocene, South America.
+</span>
+</span>
+
+by a helmet of bony plates, and the trunk was defended by an
+armour of almost hexagonal bony pieces united by sutures, and
+<a name="page_353"><span class="page">Page 353</span></a>
+exhibiting special patterns of sculpturing
+in each species. The tail was also defended by a similar armour,
+and the vertebræ were mostly fused together so as to form
+a cylindrical bony rod. In addition to the above-mentioned forms,
+a number of other Edentate animals have been discovered by the
+researches of M. Lund in the Post-Pliocene deposits of the
+Brazilian bone-caves. Amongst these are true Ant-eaters,
+Armadillos, and Sloths, many of them of gigantic size, and
+all specifically or generically distinct from existing forms.
+</p>
+
+<p class="indent">
+Passing over the aquatic orders of the <i>Sirenians</i> and
+<i>Cetaceans</i>, we come next to the great group of the Hoofed
+Quadrupeds, the remains of which are very abundant in Post-Pliocene
+deposits both in Europe and North America. Amongst the Odd-toed
+Ungulates the most important are the Rhinoceroses, of which three
+species are known to have existed in Europe during the Post-Pliocene
+period. Two of these are the well-known Pliocene forms, the
+<i>Rhinoceros Etruscus</i> and the <i>R. Megarhinus</i> still
+surviving in diminished numbers; but the most famous is the
+<i>Rhinoceros tichorhinus</i> (fig. 263), or so-called "Woolly
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 525px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig263.jpg" width="525" height="281" alt="Fig. 263" />
+<br />
+Fig. 263.&mdash;Skull of the Tichorhine Rhinoceros, the horns
+being wanting. One-tenth of the natural size. Post-Pliocene
+deposits of Europe and Asia.
+</span>
+</span>
+
+Rhinoceros." This species is known not only by innumerable bones,
+but also by a carcass, at the time of its discovery complete,
+which was found embedded in the frozen soil of Siberia towards
+the close of last century, and which was partly saved from
+destruction by the exertions of the naturalist Pallas. From this,
+we know that the Tichorhine Rhinoceros, like its associate the
+Mammoth, was provided with a coating of hair, and therefore was
+enabled to endure a more severe climate than any existing
+<a name="page_354"><span class="page">Page 354</span></a>
+species. The skin was not thrown into the folds
+which characterise most of the existing forms; and the technical
+name of the species refers to the fact that the nostrils were
+completely separated by a bony partition. The head carried two
+horns, placed one behind the other, the front one being unusually
+large. As regards its geographical range, the Woolly Rhinoceros
+is found in Europe in vast numbers north of the Alps and Pyrenees,
+and it also abounded in Siberia; so that it would appear to be a
+distinctly northern form, and to have been adapted for a temperate
+climate. It is not known to occur in Pliocene deposits, but it
+makes its first appearance in the Pre-Glacial deposits, surviving
+the Glacial period, and being found in abundance in Post-Glacial
+accumulations. It was undoubtedly a contemporary of the earlier
+races of men in Western Europe; and it may perhaps be regarded as
+being the actual substantial kernel of some of the "Dragons" of
+fable.
+</p>
+
+<p class="indent">
+The only other Odd-toed Ungulate which needs notice is the so-called
+<i>Equus fossilis</i> of the Post-Pliocene of Europe. This made
+its appearance before the Glacial period, and appears to be in
+reality identical with the existing Horse (<i>Equus caballus</i>).
+True Horses also occur in the Post-Pliocene of North America;
+but, from some cause or another, they must have been exterminated
+before historic times.
+</p>
+
+<p class="indent">
+Amongst the Even-toed Ungulates, the great <i>Hippopotamus major</i>
+of the Pliocene still continued to exist in Post-Pliocene times in
+Western Europe; and the existing Wild Boar (<i>Sus scrofa</i>),
+the parent of our domestic breeds of Pigs, appeared for the first
+time. The Old World possessed extinct representatives of its
+existing Camels, and lost types of the living Llamas inhabited
+South America. Amongst the Deer, the Post-Pliocene accumulations
+have yielded the remains of various living species, such as the
+Red Deer (<i>Cervus elaphus</i>), the Reindeer (<i>Cervus
+tarandus</i>), the Moose or Elk (<i>Alces malchis</i>), and the
+Roebuck (<i>Cervus capreolus</i>), together with a number of
+extinct forms. Among the latter, the great "Irish Elk" (<i>Cervus
+megaceros</i>) is justly celebrated both for its size and for
+the number and excellent preservation of its discovered remains.
+This extinct species (fig. 264) has been found principally in
+peat-mosses and Post-Pliocene lake-deposits, and is remarkable
+for the enormous size of the spreading antlers, which are widened
+out towards their extremities, and attain an expanse of over
+ten feet from tip to tip. It is not a genuine Elk, but is
+intermediate between the Reindeer and the Fallow-deer. Among the
+existing Deer
+<a name="page_355"><span class="page">Page 355</span></a>
+of the Post-Pliocene, the most noticeable is the
+Reindeer, an essentially northern type, existing at the present
+day in Northern Europe, and also (under the name of the "Caribou")
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 576px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig264.jpg" width="576" height="618" alt="Fig. 264" />
+<br />
+Fig. 264&mdash;Skeleton of the "Irish Elk" (<i>Cervus
+megaceros</i>). Post-Pliocene, Britain.
+</span>
+</span>
+
+in North America. When the cold of the Glacial period became
+established, this boreal species was enabled to invade Central
+and Western Europe in great herds, and its remains are found
+abundantly in cave-earths and other Post-Pliocene deposits as
+far south as the Pyrenees.
+</p>
+
+<p class="indent">
+In addition to the above, the Post-Pliocene deposits of Europe
+and North America have yielded the remains of various Sheep and
+Oxen. One of the most interesting of the latter is
+<a name="page_356"><span class="page">Page 356</span></a>
+the "Urus" or Wild Bull (<i>Bos primigenius</i>, fig. 265), which,
+though much larger than any of the existing fossils, is believed to
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 513px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig265.jpg" width="513" height="322" alt="Fig. 265" />
+<br />
+Fig. 265.&mdash;Skull of the Urns (<i>Bos primigenius</i>).
+Post-Pliocene and Recent. (After Owen.)
+</span>
+</span>
+
+be specifically undistinguishable from the domestic Ox (<i>Bos
+taurus</i>), and to be possibly the ancestor of some of the larger
+European varieties of oxen. In the earlier part of its existence
+the Urus ranged over Europe and Britain in company with the Woolly
+Rhinoceros and the Mammoth; but it long survived these, and does
+not appear to have been finally exterminated till about the twelfth
+century. Another remarkable member of the Post-Pliocene Cattle,
+also to begin with an associate of the Mammoth and Rhinoceros,
+is the European Bison or "Aurochs" (<i>Bison priscus</i>). This
+"maned" ox formerly abounded in Europe in Post-Glacial times,
+and was not rare even in the later periods of the Roman empire,
+though much diminished in numbers, and driven back into the wilder
+and more inaccessible parts of the country. At present this fine
+species has been so nearly exterminated that it no longer exists in
+Europe save in Lithuania, where its preservation has been secured
+by rigid protective laws. Lastly, the Post-Pliocene deposits have
+yielded the remains of the singular living animal which is known
+as the Musk-ox or Musk-sheep (<i>Ovibos moschatus</i>). At the
+present day, the Musk-ox is an inhabitant of the "barren grounds"
+of Arctic America, and it is remarkable for the great length of
+its hair. It is, like the Reindeer, a
+<a name="page_357"><span class="page">Page 357</span></a>
+distinctively northern animal; but it enjoyed during the Glacial
+period a much wider range than it has at the present day, the
+conditions suitable for its existence being then extended over
+a considerable portion of the northern hemisphere. Thus remains
+of the Musk-Ox are found in greater or less abundance in
+Post-Pliocene deposits over a great part of Europe, extending
+even to the south of France; and closely-related forms are found
+in similar deposits in the United States.
+</p>
+
+<p class="indent">
+Coming to the <i>Proboscideans</i>, we find that the
+<i>Mastodons</i> seem to have disappeared in Europe at the
+close of the Pliocene period, or at the very commencement
+of the Post-Pliocene. In the New World, on the other hand,
+a species of Mastodon (<i>M. Americanus</i> or <i>M.
+Ohioticus</i>) is found abundantly in deposits of Post-Pliocene
+age, from Canada to Texas. Very perfect skeletons of this
+species have been exhumed from morasses and swamps, and large
+individuals attained a length (exclusive of the tusks) of
+seventeen feet and a height of eleven feet, the tusks being
+twelve feet in length. Remains of <i>Elephants</i> are also
+abundant in the Post-Pliocene deposits of both the Old and the
+New World. Amongst these, we find in Europe the two familiar
+Pliocene species <i>E. Meridionales</i> and <i>E. Antiquus</i>
+still surviving, but in diminished numbers. With these are found
+in vast abundance the remains of the characteristic Elephant
+of the Post-Pliocene, the well-known "Mammoth" (<i>Elephas
+primigenius</i>), which is accompanied in North America by the
+nearly-allied, but more southern species, the <i>Elephas
+Americanus</i>. The Mammoth (fig. 266) is considerably larger
+than the largest of the living Elephants, the skeleton being
+over sixteen feet in length, exclusive of the tusks, and over
+nine feet in height. The tusks are bent almost into a circle,
+and are sometimes twelve feet in length, measured along their
+curvature. In the frozen soil of Siberia several carcasses of
+the Mammoth have been discovered with the flesh and skin still
+attached to the bones, the most celebrated of these being a Mammoth
+which was discovered at the beginning of this century at the
+mouth of the Lena, on the borders of the Frozen Sea, and the
+skeleton of which is now preserved at St Petersburg (fig. 266).
+From the occurrence of the remains of the Mammoth in vast numbers
+in Siberia, it might have been safely inferred that this ancient
+Elephant was able to endure a far more rigorous climate than its
+existing congeners. This inference has, however, been rendered
+a certainty by the specimens just referred to, which show that
+the Mammoth was protected against the cold by a thick coat of
+reddish-brown wool, some nine or ten inches long, interspersed
+with strong, coarse black
+<a name="page_358"><span class="page">Page 358</span></a>
+hair more than a foot in length. The
+teeth of the Mammoth (fig.267) are of the type of those of the
+existing Indian Elephant, and are found in immense numbers in
+certain localities. The Mammoth was essentially northern in its
+
+<!-- The original image description was displayed sideways -->
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 487px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig266.jpg" width="487" height="749" alt="Fig. 266" />
+<br />
+Fig. 266.&mdash;Skeleton of the Mammoth (<i>Elephas
+primigenius</i>). Portions of the integument still adhere
+to the head, and the thick skin of the soles is still
+attached to the feet. Post-Pliocene.
+</span>
+</span>
+
+distribution, never passing south of a line drawn through the
+Pyrenees, the Alps, the northern shores of the Caspian, Lake
+<a name="page_359"><span class="page">Page 359</span></a>
+Baikal, Kamschatka, and the Stanovi Mountains (Dawkins). It
+occurs in the Pre-Glacial forest-bed of Cromer in Norfolk,
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 418px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig267.jpg" width="418" height="324" alt="Fig. 267" />
+<br />
+Fig. 267.&mdash;Molar tooth of the Mammoth (<i>Elephas
+primigenius</i>), upper jaw, right side, one-third of the natural
+size. <i>a</i>, Grinding surface; <i>b</i>, Side view.
+Post-Pliocene.
+</span>
+</span>
+
+survived the Glacial period, and is found abundantly in
+Post-Glacial deposits in France, Germany, Britain, Russia in
+Europe, Asia, and North America, being often associated with the
+Reindeer, Lemming, and Musk-ox. That it survived into the earlier
+portion of the human period is unquestionable, its remains having
+been found in a great number of instances associated with
+implements of human manufacture; whilst in one instance a
+recognisable portrait of it has been discovered, carved on bone.
+</p>
+
+<p class="indent">
+Amongst other Elephants which occur in Post-Pliocene deposits
+may be mentioned, as of special interest, the pigmy Elephants of
+Malta. One of these&mdash;the <i>Elephas Melitensis</i>, or
+so-called "Donkey-Elephant"&mdash;was not more than four and a
+half feet in height. The other&mdash;the <i>Elephas Falconeri</i>,
+of Busk&mdash;was still smaller, its average height at the
+withers not exceeding two and a half to three feet.
+</p>
+
+<p class="indent">
+Whilst herbivorous animals abounded during the Post-Pliocene,
+we have ample evidence of the coexistence with them of a number
+of Carnivorous forms, both in the New and the Old World. The
+Bears are represented in Europe by at least three species, two
+of which&mdash;namely, the great Grizzly Bear (<i>Ursus ferox</i>)
+and the smaller Brown Bear (<i>Ursus arctos</i>)&mdash;are in
+existence at the present day. The third species is the
+<a name="page_360"><span class="page">Page 360</span></a>
+celebrated Cave-bear
+(<i>Ursus spelœus</i>, fig. 268), which is now extinct. The
+Cave-bear exceeded in its dimensions the largest of modern Bears;
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 497px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig268.jpg" width="497" height="263" alt="Fig. 268" />
+<br />
+Fig. 268.&mdash;Skull of <i>Ursus spelpeus</i>. Post-Pliocene,
+Europe. One-sixth of the natural size.
+</span>
+</span>
+
+and its remains, as its name implies; have been found mainly in
+cavern-deposits. Enormous numbers of this large and ferocious
+species must have lived in Europe in Post-Glacial times; and that
+they survived into the human period, is clearly shown by the common
+association of their bones with the implements of man. They are
+occasionally accompanied by the remains of a Glutton (the <i>Gulo
+spelœus</i>), which does not appear to be really separable from
+the existing Wolverine or Glutton of northern regions (the <i>Gulo
+luscus</i>). In addition, we meet with the bones of the Wolf, Fox,
+Weasel, Otter, Badger, Wild Cat, Panther, Hyæna, and Lion,
+&amp;c., together with the extinct <i>Machairodus</i> or "Sabre-toothed
+Tiger." The only two of these that deserve further mention are
+the Hyæna and the Lion. The Cave-hyæna (<i>Hyœna
+spelœa</i>, fig. 269) is regarded by high authorities as nothing
+more than a variety of the living Spotted Hyæna (<i>H.
+Crocuta</i>) of South Africa. This well-known species inhabited Britain
+and a considerable portion of Europe during a large part of the
+Post-Pliocene period; and its remains often occur in great abundance.
+Indeed, some caves, such as the Kirkdale Cavern in Yorkshire, were
+dens inhabited during long periods by these animals, and thus contain
+the remains of numerous individuals and of successive generations of
+Hyænas, together with innumerable gnawed and bitten bones of
+their prey. That the Cave-hyæna was a contemporary with Man in
+Western Europe during Post-Glacial times is shown beyond a doubt by
+the common association of its bones with human implements.
+</p>
+
+<p class="indent">
+<a name="page_361"><span class="page">Page 361</span></a>
+Lastly, the so-called Cave-lion (<i>Felis spelœa</i>), long
+supposed to be a distinct species, has been shown to be nothing
+
+<span style="float: left; width: 100%; text-align: center;">
+<span style="margin: 4px; width: 454px;
+  font-size: smaller; text-align: center;">
+<img src="images/fig269.jpg" width="454" height="245" alt="Fig. 269" />
+<br />
+Fig. 269.&mdash;Skull of <i>Hyœna spelœa</i>, one-fourth
+of the natural size. Post-Phocene, Europe.
+</span>
+</span>
+
+more than a large variety of the existing Lion (<i>Felis leo</i>).
+This animal inhabited Britain and Western Europe in times posterior
+to the Glacial period, and was a contemporary of the Cave-hyæna,
+Cave-bear, Woolly Rhinoceros, and Mammoth. The Cave-lion also
+unquestionably survived into the earlier portion of the human
+period in Europe.
+</p>
+
+<p class="indent">
+The Post-Pliocene deposits of Europe have further yielded the remains
+of numerous <i>Rodents</i>&mdash;such as the Beaver, the Northern
+Lemming, Marmots, Mice, Voles, Rabbits, &amp;c.&mdash;together with
+the gigantic extinct Beaver known as the <i>Trogontherium Cuvieri</i>
+(fig. 270). The great <i>Castoroides Ohioensis</i> of the
+
+<span style="float: right; margin: 4px; width: 258px;
+  font-size: smaller; text-align: justify;">
+<img src="images/fig270.jpg" width="258" height="148" alt="Fig. 270" />
+<br />
+Fig. 270.&mdash;Lower jaw of <i>Trogontherium Cuvieri</i>, one-fourth
+of the natural size. Post-Pliocene, Britain.
+</span>
+
+Post-Pliocene of North America is also a great extinct Beaver,
+which reached a length of about five feet. Lastly, the Brazilian
+bone-caves have yielded the remains of numerous Rodents of types
+now characteristic of South America, such as Guinea-pigs, Capybaras,
+tree-inhabiting Porcupines, and Coypus.
+</p>
+
+<p class="indent">
+The deposits just alluded to have further yielded the remains of
+various Monkeys, such as Howling Monkeys, Squirrel Monkeys, and
+Marmosets, all of which belong to the group of <i>Quadrumana</i>
+which is now exclusively confined to the
+<a name="page_362"><span class="page">Page 362</span></a>
+South American continent&mdash;namely, the "Platyrhine" Monkeys.
+</p>
+
+<p class="indent">
+We still have very briefly to consider the occurrence of Man
+in Post-Pliocene deposits; but before doing so, it will be well
+to draw attention to the evidence afforded by the Post-Pliocene
+Mammals as to the climate of Western Europe at this period. The
+chief point which we have to notice is, that a considerable
+revolution of opinion has taken place on this point. It was
+originally believed that the presence of such animals as Elephants,
+Lions, the Rhinoceros, and the Hippopotamus afforded an irrefragable
+proof that the climate of Europe must have been a warm one, at any
+rate during Post-Glacial times. The existence, also, of numbers
+of Mammoths in Siberia, was further supposed to indicate that
+this high temperature extended itself very far north. Upon the
+whole, however, the evidence is against this view. Not only is
+there great difficulty in supposing that the Arctic conditions of
+the Glacial period were immediately followed by anything warmer
+than a cold-temperate climate; but there is nothing in the nature
+of the Mammals themselves which would absolutely forbid their
+living in a temperate climate. The <i>Hippopotamus major</i>,
+though probably clad in hair, offers some difficulty&mdash;since,
+as pointed out by Professor Busk, it must have required a climate
+sufficiently warm to insure that the rivers were not frozen over
+in the winter; but it was probably a migratory animal, and its
+occurrence may be accounted for by this. The Woolly Rhinoceros
+and the Mammoth are known with certainty to have been protected
+with a thick covering of wool and hair; and their extension
+northwards need not necessarily have been limited by anything
+except the absence of a sufficiently luxuriant vegetation to
+afford them food. The great American Mastodon, though not certainly
+known to have possessed a hairy covering, has been shown to have
+lived upon the shoots of Spruce and Firs, trees characteristic of
+temperate regions&mdash;as shown by the undigested food which has
+been found with its skeleton, occupying the place of the stomach.
+The Lions and Hyænas, again, as shown by Professor Boyd Dawkins,
+do not indicate necessarily a warm climate. Wherever a sufficiency
+of herbivorous animals to supply them with food can live, there
+they can live also; and they have therefore no special bearing
+upon the question of climate. After a review of the whole evidence,
+Professor Dawkins concludes that the nearest approach at the
+present day to the Post-Pliocene climate of Western Europe is
+to be found in the climate of the great Siberian plains which
+stretch from the Altai Mountains to the Frozen Sea. "Covered
+<a name="page_363"><span class="page">Page 363</span></a>
+by impenetrable forests, for the most part
+of Birch, Poplar, Larch, and Pines, and low creeping dwarf Cedars,
+they present every gradation in climate from the temperate to that
+in which the cold is too severe to admit of the growth of trees,
+which decrease in size as the traveller advances northwards, and
+are replaced by the grey mosses and lichens that cover the low
+marshy 'tundras.' The maximum winter cold, registered by Admiral
+Von Wrangel at Nishne Kolymsk, on the banks of the Kolyma,
+is&mdash;65&deg; in January. 'Then breathing becomes difficult;
+the Reindeer, that citizen of the Polar region, withdraws to the
+deepest thicket of the forest, and stands there motionless as
+if deprived of life;' and trees burst asunder with the cold.
+Throughout this area roam Elks, Black Bears, Foxes, Sables, and
+Wolves, that afford subsistence to the Jakutian and Tungusian
+fur-hunters. In the northern part countless herds of Reindeer,
+Elks, Foxes, and Wolverines make up for the poverty of vegetation
+by the rich abundance of animal life. 'Enormous flights of Swans,
+Geese, and Ducks arrive in the spring, and seek deserts where
+they may moult and build their nests in safety. Ptarmigans run in
+troops amongst the bushes; little Snipes are busy along the brooks
+and in the morasses; the social Crows seek the neighbourhood of
+new habitations; and when the sun shines in spring, one may even
+sometimes hear the cheerful note of the Finch, and in autumn
+that of the Thrush.' Throughout this region of woods, a hardy,
+middle-sized breed of horses lives under the mastership and care
+of man, and is eminently adapted to bear the severity of the
+climate.... The only limit to their northern range is the difficulty
+of obtaining food. The severity of the winter through the southern
+portion of this vast wooded area is almost compensated for by the
+summer heat and its marvellous effect on
+vegetation."&mdash;(Dawkins, 'Monograph of Pleistocene Mammalia.')
+</p>
+
+<p class="indent">
+Finally, a few words must be said as to the occurrence of the
+remains of Man in Post-Pliocene deposits. That Man existed in
+Western Europe and in Britain during the Post-Pliocene period, is
+placed beyond a doubt by the occurrence of his bones in deposits
+of this age, along with the much more frequent occurrence of
+implements of human manufacture. At what precise point of time
+during the Post-Pliocene period he first made his appearance is
+still a matter of conjecture. Recent researches would render
+it probable that the early inhabitants of Britain and Western
+Europe were witnesses of the stupendous phenomena of the Glacial
+period; but this cannot be said to have been demonstrated. That
+Man existed in these
+<a name="page_364"><span class="page">Page 364</span></a>
+regions during the
+Post-Glacial division of Post-Pliocene time cannot be doubted
+for a moment. As to the physical peculiarities of the ancient
+races that lived with the Mammoth and the Woolly Rhinoceros,
+little is known compared with what we may some day hope to know.
+Such information as we have, however, based principally on the
+skulls of the Engis, Neanderthal, Cro-Magnon, and Bruniquel
+caverns, would lead to the conclusion that Post-Pliocene Man
+was in no respect inferior in his organisation to, or less
+highly developed than, many existing races. All the known
+skulls of this period, with the single exception of the
+Neanderthal cranium, are in all respects average and normal in
+their characters; and even the Neanderthal skull possessed a
+cubic capacity at least equal to that of some existing races. The
+implements of Post-Pliocene Man are exclusively of stone or bone;
+and the former are invariably of rude shape and <i>undressed</i>.
+These "palæolithic" tools (Gr. <i>palaios</i>; ancient;
+<i>lithos</i>, stone) point to a very early condition of the
+arts; since the men of the earlier portion of the Recent period,
+though likewise unacquainted with the metals, were in the habit
+of polishing or dressing the stone implements which they
+fabricated.
+</p>
+
+<p class="indent">
+It is impossible here to enter further into this subject; and
+it would be useless to do so without entering as well into a
+consideration of the human remains of the Recent period&mdash;a
+period which lies outside the province of the present work. So
+far as Post-Pliocene Man is concerned, the chief points which
+the palæontological student has to remember have been
+elsewhere summarised by the author as follows:&mdash;
+</p>
+
+<p class="indent">
+1. Man unquestionably existed during the later portion of what
+Sir Charles Lyell has termed the "Post-Pliocene" period. In other
+words, Man's existence dates back to a time when several remarkable
+Mammals, previously mentioned, had not yet become extinct; but he
+does not date back to a time anterior to the present <i>Molluscan</i>
+fauna.
+</p>
+
+<p class="indent">
+2. The antiquity of the so-called Post-Pliocene period is a matter
+which must be mainly settled by the evidence of Geology proper,
+and need not be discussed here.
+</p>
+
+<p class="indent">
+3. The extinct Mammals with which man coexisted in Western Europe
+are mostly of large size, the most important being the Mammoth
+(<i>Elephas primogenius</i>), the Woolly Rhinoceros (<i>Rhinoceros
+tichorhinus</i>), the Cave-lion (<i>Felis spelœa</i>), the
+Cave-hyæna(<i>Hyœna spelœa</i>), and the Cave-bear
+(<i>Ursus spelœus</i>). We do not know the causes which led
+to the extinction of these Mammals; but we know that hardly any
+Mammalian species has become extinct during the historical period.
+</p>
+
+<p class="indent">
+<a name="page_365"><span class="page">Page 365</span></a>
+4. The extinct Mammals with which man coexisted are referable in
+many cases to species which presumably required a very different
+climate to that now prevailing in Western Europe. How long a period,
+however, has been consumed in the bringing about of the climatic
+changes thus indicated, we have no means of calculating with any
+approach to accuracy.
+</p>
+
+<p class="indent">
+5. Some of the deposits in which the remains of man have been
+found associated with the bones of extinct Mammals, are such as
+to show incontestably that great changes in the physical geography
+and surface-configuration of Western Europe have taken place
+since the period of their accumulation. We have, however, no
+means at present of judging of the lapse of time thus indicated
+except by analogies and comparisons which may be disputed.
+</p>
+
+<p class="indent">
+6. The human implements which are associated with the remains
+of extinct Mammals, themselves bear evidence of an exceedingly
+barbarous condition of the human species. Post-Pliocene or
+"Palæolithic" Man was clearly unacquainted with the use
+of any of the metals. Not only so, but the workmanship of these
+ancient races was much inferior to that of the later tribes, who
+were also ignorant of the metals, and who also used nothing but
+weapons and tools of stone, bone, &amp;c.
+</p>
+
+<p class="indent">
+7. Lastly, it is only with the human remains of the Post-Pliocene
+period that the palæontologist proper has to deal. When we
+enter the "Recent" period, in which the remains of Man are
+associated with those of <i>existing species of Mammals</i>, we
+pass out of the region of pure palæontology into the domain
+of the Archæologist and the Ethnologist.
+</p>
+
+<h4>LITERATURE.</h4>
+
+<p class="indent">
+The following are some of the principal works and memoirs to which
+the student may refer for information as to the Post-Pliocene
+deposits and the remains which they contain, as well as to the
+primitive races of mankind:&mdash;
+</p>
+
+<table border="0" cellspacing="0">
+<tr><td class="right" valign="top">(1)</td>
+ <td>'Elements of Geology.' Lyell.</td>
+</tr><tr><td class="right" valign="top">(2)</td>
+ <td>'Antiquity of Man.' Lyell.</td>
+</tr><tr><td class="right" valign="top">(3)</td>
+ <td>'Palæontological Memoirs.' Falconer.</td>
+</tr><tr><td class="right" valign="top">(4)</td>
+ <td>'The Great Ice-age.' James Geikie.</td>
+</tr><tr><td class="right" valign="top">(5)</td>
+ <td>'Manual of Palæontology.' Owen.</td>
+</tr><tr><td class="right" valign="top">(6)</td>
+ <td>'British Fossil Mammals and Birds.' Owen.</td>
+</tr><tr><td class="right" valign="top">(7)</td>
+ <td>'Cave-Hunting.' Boyd Dawkins.</td>
+</tr><tr><td class="right" valign="top">(8)</td>
+ <td>'Prehistoric Times.' Lubbock.</td>
+</tr><tr><td class="right" valign="top">(9)</td>
+ <td>'Ancient Stone Implements.' Evans.</td>
+</tr><tr><td class="right" valign="top">(10)</td>
+ <td>'Prehistoric Man.' Daniel Wilson.</td>
+</tr><tr><td class="right" valign="top">(11)</td>
+ <td>'Prehistoric Races of the United States.' Foster.</td>
+</tr><tr><td class="right" valign="top">(12)</td>
+ <td>'Manual of Geology.' Dana.</td>
+</tr><tr><td class="right" valign="top">
+<a name="page_366"><span class="page">Page 366</span></a>
+  (13)</td>
+ <td>'Monograph of Pleistocene Mammalia' (Palæontographical
+   Society). Boyd Dawkins and Sanford.</td>
+</tr><tr><td class="right" valign="top">(14)</td>
+ <td>'Monograph of the Post-Tertiary Entomostraca of Scotland,
+  &amp;c., with an Introduction on the Post-Tertiary Deposits
+  of Scotland' (Ibid.) G. S. Brady, H. W. Crosskey, and D.
+  Robertson.</td>
+</tr><tr><td class="right" valign="top">(15)</td>
+ <td>"Reports on Kent's Cavern"&mdash;'British Association
+  Reports.' Pengelly.</td>
+</tr><tr><td class="right" valign="top">(16)</td>
+ <td>"Reports on the Victoria Cavern, Settle"&mdash;'British
+  Association Reports.' Tiddeman.</td>
+</tr><tr><td class="right" valign="top">(17)</td>
+ <td>'Ossemens Fossiles.' Cuvier.</td>
+</tr><tr><td class="right" valign="top">(18)</td>
+ <td>'Reliquiæ Diluvianæ.' Buckland.</td>
+</tr><tr><td class="right" valign="top">(19)</td>
+ <td>"Fossil Mammalia"&mdash;'Zoology of the Voyage of the
+  Beagle.' Owen.</td>
+</tr><tr><td class="right" valign="top">(20)</td>
+ <td>'Description of the Tooth and Part of the Skeleton of
+  the <i>Glyptodon</i>.' Owen.</td>
+</tr><tr><td class="right" valign="top">(21)</td>
+ <td>"Memoir on the Extinct Sloth Tribe of North
+  America"&mdash;'Smithsonian Contributions to Knowledge.'
+  Leidy.</td>
+</tr><tr><td class="right" valign="top">(22)</td>
+ <td>"Report on Extinct Mammals of Australia"&mdash;'British
+  Association,' 1844. Owen.</td>
+</tr><tr><td class="right" valign="top">(23)</td>
+ <td>'Description of the Skeleton of an Extinct Gigantic
+  Sloth (<i>Mylodon robtutus</i>).' Owen.</td>
+</tr><tr><td class="right" valign="top">(24)</td>
+ <td>"Affinities and Probable Habits of Thylacoleo"&mdash;'Quart.
+  Journ. Geol. Soc.,' vol. xxiv. Flower.</td>
+</tr><tr><td class="right" valign="top">(25)</td>
+ <td>'Prodromus of the Palæontology of Victoria.'
+  M'Coy.</td>
+</tr><tr><td class="right" valign="top">(26)</td>
+ <td>'Les Ossemens Fossiles des Cavernes de Liège.'
+  Schmerling.</td>
+</tr><tr><td class="right" valign="top">(27)</td>
+ <td>'Die Fauna der Pfahlbauten in der Schweiz.'
+  R&uuml;timeyer.</td>
+</tr><tr><td class="right" valign="top">(28)</td>
+ <td>"Extinct and Existing Bovine Animals of
+  Scandinavia"&mdash;'Annals of Natural History,' ser. 2, vol.
+  iv., 1849. Nilsson.</td>
+</tr><tr><td class="right" valign="top">(29)</td>
+ <td>'Man's Place in Nature.' Huxley.</td>
+</tr><tr><td class="right" valign="top">(30)</td>
+ <td>'Les Temps Antéhistoriques en Belgique.'
+  Dupont.</td>
+</tr><tr><td class="right" valign="top">(31)</td>
+ <td>"Classification of the Pleistocene Strata of Britain and
+  the Continent"&mdash;'Quart. Journ. Geol. Soc.,' vol. xxviii.
+  Boyd Dawkins.</td>
+</tr><tr><td class="right" valign="top">(32)</td>
+ <td>'Distribution of the Post-Glacial Mammalia' (Ibid.), vol.
+  xxv. Boyd Dawkins.</td>
+</tr><tr><td class="right" valign="top">(33)</td>
+ <td>'On British Fossil Oxen' (Ibid.), vols. xxii. and xxiii.
+  Boyd Dawkins.</td>
+</tr><tr><td class="right" valign="top">(34)</td>
+ <td>'British Prehistoric Mammals' (Congress of Prehistoric
+  Archæology, 1868). Boyd Dawkins.</td>
+</tr><tr><td class="right" valign="top">(35)</td>
+ <td>'Reliquiæ Aquitanicæ.' Lartet and
+  Christy.</td>
+</tr><tr><td class="right" valign="top">(36)</td>
+ <td>'Zoologie et Paléontologie Fran&ccedil;aises.'
+  Gervais.</td>
+</tr><tr><td class="right" valign="top">(37)</td>
+ <td>'Notes on the Post-Pliocene Geology of Canada.' Dawson.</td>
+</tr><tr><td class="right" valign="top">(38)</td>
+ <td>"On the Connection between the existing Fauna and Flora of
+  Great Britain and certain Geological Changes"&mdash;'Mem. Geol.
+  Survey.' Edward Forbes.</td>
+</tr><tr><td class="right" valign="top">(39)</td>
+ <td>'Cavern-Researches.' M'Enery. Edited by Vivian.</td>
+</tr><tr><td class="right" valign="top">(40)</td>
+ <td>"Quaternary Gravels"&mdash;'Quart. Journ. Geol. Soc.,' vol.
+  xxv. Tylor.</td></tr>
+</table>
+
+<h3>
+<a name="page_367"><span class="page">Page 367</span></a>
+CHAPTER XXIII.</h3>
+
+<p class="subtitle">
+THE SUCCESSION OF LIFE UPON THE GLOBE.
+</p>
+
+<p class="indent">
+In conclusion, it may not be out of place if we attempt to summarise,
+in the briefest possible manner, some of the principal results
+which may be deduced as to the succession of life upon the earth
+from the facts which have in the preceding portion of this work
+been passed in review. That there was a time when the earth was
+void of life is universally admitted, though it may be that the
+geological record gives us no direct evidence of this. That the
+globe of to-day is peopled with innumerable forms of life whose
+term of existence has been, for the most part, but as it were
+of yesterday, is likewise an assertion beyond dispute. Can we
+in any way connect the present with the remote past, and can we
+indicate even imperfectly the conditions and laws under which the
+existing order was brought about? The long series of fossiliferous
+deposits, with their almost countless organic remains, is the
+link between what has been and what is; and if any answer to the
+above question can be arrived at, it will be by the careful and
+conscientious study of the facts of Palæontology. In the present
+state of our knowledge, it may be safely said that anything like
+a dogmatic or positive opinion as to the precise sequence of
+living forms upon the globe, and still more as to the manner in
+which this sequence may have been brought about, is incapable of
+scientific proof. There are, however, certain general deductions
+from the known facts which may be regarded as certainly established.
+</p>
+
+<p class="indent">
+In the first place, it is certain that there has been a
+<i>succession</i> of life upon the earth, different specific and
+generic types succeeding one another in successive periods. It
+follows from this, that the animals and plants with which we are
+familiar as living, were not always upon the earth, but that they
+have been preceded by numerous races more or less differing from
+them. What is true of the species of animals and plants, is true
+also of the higher zoological divisions; and it is, in the second
+place, quite certain that there has been a similar <i>succession</i>
+in the order of appearance of the primary groups ("sub-kingdoms,"
+"classes," &amp;c.) of animals and vegetables. These great groups did
+not all come into existence at once, but they made their appearance
+successively. It is true that we cannot be said to be certainly
+acquainted with the first <i>absolute</i>
+<a name="page_368"><span class="page">Page 368</span></a>
+appearance of any great group of animals. No one dare assert
+positively that the apparent first appearance of Fishes in the
+Upper Silurian is really their first introduction upon the earth:
+indeed, there is a strong probability against any such supposition.
+To whatever extent, however, future discoveries may push back the
+first advent of any or of all of the great groups of life, there is
+no likelihood that anything will be found out which will materially
+alter the <i>relative</i> succession of these groups as at present
+known to us. It is not likely, for example, that the future has
+in store for us any discovery by which it would be shown that
+Fishes were in existence before Molluscs, or that Mammals made their
+appearance before Fishes. The sub-kingdoms of Invertebrate animals
+were all represented in Cambrian times&mdash;and it might therefore
+be inferred that <i>these</i> had all come simultaneously into
+existence; but it is clear that this inference, though incapable
+of actual disproof, is in the last degree improbable. Anterior
+to the Cambrian is the great series of the Laurentian, which,
+owing to the metamorphism to which it has been subjected, has so
+far yielded but the singular <i>Eozoön</i>. We may be certain,
+however, that others of the Invertebrate sub-kingdoms besides
+the Protozoa were in existence in the Laurentian period; and we
+may infer from known analogies that they appeared successively,
+and not simultaneously.
+</p>
+
+<p class="indent">
+When we come to smaller divisions than the sub-kingdoms&mdash;such
+as classes, orders, and families&mdash;a similar succession of groups
+is observable. The different classes of any given sub-kingdom, or
+the different orders of any given class, do not make their
+appearance together and all at once, but they are introduced upon
+the earth in <i>succession</i>. More than this, the different classes
+of a sub-kingdom, or the different orders of a class, <i>in the
+main succeed one another in the relative order of their zoological
+rank&mdash;the lower groups appearing first and the higher groups
+last</i>. It is true that in the Cambrian formation&mdash;the
+earliest series of sediments in which fossils are abundant&mdash;we
+find numerous groups, some very low, others very high, in the
+zoological scale, which <i>appear</i> to have simultaneously
+flashed into existence. For reasons stated above, however, we
+cannot accept this appearance as real; and we must believe that
+many of the Cambrian groups of animals really came into being long
+before the commencement of the Cambrian period. At any rate, in the
+long series of fossiliferous deposits of later date than the Cambrian
+the above-stated rule holds good as a broad generalisation&mdash;that
+the lower groups, namely, precede the higher in point of time;
+<a name="page_369"><span class="page">Page 369</span></a>
+and though there are apparent exceptions to the rule, there are none
+of such a nature as not to admit of explanation. Some of the leading
+facts upon which this generalisarion is founded will be enumerated
+immediately; but it will be well, in the first place, to consider
+briefly what we precisely mean when we speak of "higher" and "lower"
+groups.
+</p>
+
+<p class="indent">
+It is well known that naturalists are in the habit of "classifying"
+the innumerable animals which now exist upon the globe; or, in
+other words, of systematically arranging them into groups. The
+precise arrangement adopted by one naturalist may differ in minor
+details from that adopted by another; but all are agreed as to the
+fundamental points of classification, and all, therefore, agree in
+placing certain groups in a certain sequence. What, then, is the
+principle upon which this sequence is based? Why, for example, are
+the Sponges placed below the Corals; these below the Sea-urchins;
+and these, again, below the Shell-fish? Without entering into
+a discussion of the principles of zoological classification,
+which would here be out of place, it must be sufficient to say
+that the sequence in question is based upon the <i>relative type
+of organisation</i> of the groups of animals classified. The
+Corals are placed above the Sponges upon the ground that, regarded
+as a whole, the <i>plan or type of structure</i> of a Coral is
+more complex than that of a Sponge. It is not in the slightest
+degree that the Sponge is in any respect less highly organised
+or less perfect, as a Sponge, than is the Coral as a Coral. Each
+is equally perfect in its own way; but the structural pattern
+of the Coral is the highest, and therefore it occupies a higher
+place in the zoological scale. It is upon this principle, then,
+that the primary subdivisions of the animal kingdom (the so-called
+"sub-kingdoms") are arranged in a certain order. Coming, again, to
+the minor subdivisions (classes, orders, &amp;c.) of each sub-kingdom,
+we find a different but entirely analogous principle employed as
+a means of classification. The numerous animals belonging to
+any given sub-kingdom are formed upon the same fundamental plan
+of structure; but they nevertheless admit of being arranged in
+a regular series of groups. All the Shell-fish, for example,
+are built upon a common plan, this plan representing the ideal
+Mollusc; but there are at the same time various groups of the
+<i>Mollusca</i>, and these groups admit of an arrangement in a
+given sequence. The principle adopted in this case is simply of
+<i>the relative elaboration of the common type</i>. The Oyster
+is built upon the same ground-plan as the Cuttle-fish; but this
+plan is carried out with much greater elaboration, and with many
+more complexities, in the latter than in the former: and
+<a name="page_370"><span class="page">Page 370</span></a>
+in accordance with this, the <i>Cephalopoda</i> constitute a
+higher group than the Bivalve Shell-fish. As in the case of
+superiority of structural type, so in this case also, it is not
+in the least that the Oyster is an <i>imperfect</i> animal. On
+the contrary, it is just as perfectly adapted by its
+organisation to fill its own sphere and to meet the exigencies
+of its own existence as is the Cuttle-fish; but the latter lives
+a life which is, physiologically, higher than the former, and its
+organisation is correspondingly increased in complexity.
+</p>
+
+<p class="indent">
+This being understood, it may be repeated that, in the main,
+the succession of life upon the globe in point of <i>time</i>
+has corresponded with the relative order of succession of the
+great groups of animals in <i>zoological rank</i>; and some of
+the more striking examples of this may be here alluded to. Amongst
+the <i>Echinoderms</i>, for instance, the two orders generally
+admitted to be the "lowest" in the zoological scale&mdash;namely,
+the <i>Crinoids</i> and the <i>Cystoids</i>&mdash;are likewise the
+oldest, both, appearing in the Cambrian, the former slowly dying
+out as we approach the Recent period, and the latter disappearing
+wholly before the close of the Palæozoic period. Amongst the
+<i>Crustaceans</i>, the ancient groups of the Trilobites, Ostracodes,
+Phyllopods, Eurypterids, and Limuloids, some of which exist at the
+present day, are all "low" types; whereas the highly-organised
+Decapods do not make their appearance till near the close of the
+Palæozoic epoch, and they do not become abundant till we reach
+Mesozoic times. Amongst the <i>Mollusca</i>, those Bivalves which
+possess breathing-tubes (the "siphonate" Bivalves) are generally
+admitted to be higher than those which are destitute of these
+organs (the "asiphonate" Bivalves); and the latter are especially
+characteristic of the Palæozoic period, whilst the former abound
+in Mesozoic and Kainozoic formations. Similarly, the Univalves
+with breathing-tubes and a corresponding notch in the mouth of the
+shell ("siphonostomatous" Univalves) are regarded as higher in the
+scale than the round-mouthed vegetable-eating Sea-snails, in which
+no respiratory siphons exist ("holostomatous" Univalves); but the
+latter abound in the Palæozoic rocks&mdash;whereas the former
+do not make their appearance till the Jurassic period, and their
+higher groups do not seem to have existed till the close of the
+Cretaceous. The <i>Cephalopods</i>, again&mdash;the highest of all
+the groups of Mollusca&mdash;are represented in the Palæozoic
+rocks exclusively by Tetrabranchiate forms, which constitute the
+lowest of the two orders of this class; whereas the more highly
+specialised Dibranchiates do not make their appearance till the
+commencement of the Mesozoic. The Palæozoic
+<a name="page_371"><span class="page">Page 371</span></a>
+Tetrabranchiates, also, are of a much simpler type than the highly
+complex <i>Ammonitidœ</i> of the Mesozoic.
+</p>
+
+<p class="indent">
+Similar facts are observable amongst the <i>Vertebrate animals</i>.
+The Fishes are the lowest class of Vertebrates, and they are the
+first to appear, their first certain occurrence being in the
+Upper Silurian; whilst, even if the Lower Silurian and Upper
+Cambrian "Conodonts" were shown to be the teeth of Fishes, there
+would still remain the enormously long periods of the Laurentian
+and Lower Cambrian, during which there were Invertebrates, but no
+Vertebrates. The <i>Amphibians</i>, the next class in zoological
+order, appears later than the Fishes, and is not represented
+till the Carboniferous; whilst its highest group (that of the
+Frogs and Toads) does not make its entrance upon the scene till
+Tertiary times are reached. The class of the <i>Reptiles</i>,
+again, the next in order, does not appear till the Permian, and
+therefore not till after Amphibians of very varied forms had
+been in existence for a protracted period. The <i>Birds</i> seem
+to be undoubtedly later than the Reptiles; but, owing to the
+uncertainty as to the exact point of their first appearance, it
+cannot be positively asserted that they preceded Mammals, as they
+should have done. Finally, the Mesozoic types of <i>Mammals</i> are
+mainly, if not exclusively, referable to the <i>Marsupials</i>,
+one of the lowest orders of the class; whilst the higher orders
+of the "Placental" Quadrupeds are not with certainty known to
+have existed prior to the commencement of the Tertiary period.
+</p>
+
+<p class="indent">
+Facts of a very similar nature are offered by the succession of
+Plants upon the globe. Thus the vegetation of the Palæozoic
+period consisted principally of the lowly-organised groups of
+the Cryptogamous or Flowerless plants. The Mesozoic formations,
+up to the Chalk, are especially characterised by the naked-seeded
+Flowering plants&mdash;the Conifers and the Cycads; whilst the
+higher groups of the Angiospermous Exogens and Monocotyledons
+characterise the Upper Cretaceous and Tertiary rocks.
+</p>
+
+<p class="indent">
+Facts of the above nature&mdash;and they could be greatly
+multiplied&mdash;seem to point clearly to the existence of some
+law of progression, though we certainly are not yet in a position
+to formulate this law, or to indicate the precise manner in which
+it has operated. Two considerations, also, must not be overlooked.
+In the first place, there are various groups, some of them highly
+organised, which make their appearance at an extremely ancient
+date, but which continue throughout geological time almost
+unchanged, and certainly unprogressive. Many of these "persistent
+types" are known&mdash;such as various of the
+<a name="page_372"><span class="page">Page 372</span></a>
+<i>Foraminifera</i>, the <i>Lingulœ</i>, the <i>Nautili</i>,
+&amp;c.; and they indicate that under given conditions, at present
+unknown to us, it is possible for a life-form to subsist for an
+almost indefinite period without any important modification of
+its structure. In the second place, whilst the facts above
+mentioned point to some general law of progression of the great
+zoological groups, it cannot be asserted that the primeval types
+<i>of any given group</i> are necessarily "lower," zoologically
+speaking, than their modern representatives. Nor does this seem to
+be at all necessary for the establishment of the law in question.
+It cannot be asserted, for example, that the Ganoid and Placoid
+Fishes of the Upper Silurian are in themselves less highly organised
+than their existing representatives; nor can it even be asserted
+that the Ganoid and Placoid orders are low <i>groups</i> of the
+class <i>Pisces</i>. On the contrary, they are high groups; but
+then it must be remembered that these are probably not really
+the first Fishes, and that if we meet with Fishes at some future
+time in the Lower Silurian or Cambrian, these may easily prove
+to be representatives of the lower orders of the class. This
+question cannot be further entered into here, as its discussion
+could be carried out to an almost unlimited length; but whilst
+there are facts pointing both ways, it appears that at present
+we are not justified in asserting that the earlier types of each
+group&mdash;so far as these are known to us, or really are without
+predecessors&mdash;are <i>necessarily</i> or <i>invariably</i> more
+"degraded" or "embryonic" in their structure than their more
+modern representatives.
+</p>
+
+<p class="indent">
+It remains to consider very briefly how far Palæontology
+supports the doctrine of "Evolution," as it is called; and this,
+too, is a question of almost infinite dimensions, which can but
+be glanced at here. Does Palæontology teach us that the
+almost innumerable kinds of animals and plants which we know to
+have successively flourished upon the earth in past times were
+produced separately and wholly independently of each other, at
+successive periods? or does it point to the theory that a large
+number of these supposed distinct forms, have been in reality
+produced by the slow modification of a comparatively small number
+of primitive types? Upon the whole, it must be unhesitatingly
+replied that the evidence of Palæontology is in favour of
+the view that the succession of life-forms upon the globe has
+been to a large extent regulated by some orderly and
+constantly-acting law of modification and evolution. Upon no
+other theory can we comprehend how the fauna of any given
+formation is more closely related to that of the formation next
+below in the series, and to that of
+<a name="page_373"><span class="page">Page 373</span></a>
+the formation next above, than to that of any other series of
+deposits. Upon no other view can we comprehend why the
+Post-Tertiary Mammals of South America should consist
+principally of Edentates, Llamas, Tapirs, Peccaries, Platyrhine
+Monkeys, and other forms now characterising this continent;
+whilst those of Australia should be wholly referable to the
+order of Marsupials. On no other view can we explain the common
+occurrence of "intermediate" or "transitional" forms of life,
+filling in the gaps between groups now widely distinct.
+</p>
+
+<p class="indent">
+On the other hand, there are facts which point clearly to the
+existence of some law other than that of evolution, and probably
+of a deeper and more far-reaching character. Upon no theory of
+evolution can we find a satisfactory explanation for the constant
+introduction throughout geological time of new forms of life, which
+do not appear to have been preceded by pre-existent allied types;
+The Graptolites and Trilobites have no known predecessors, and leave
+no known successors. The Insects appear suddenly in the Devonian,
+and the Arachnides and Myriapods in the Carboniferous, under
+well-differentiated and highly-specialised types. The Dibranchiate
+Cephalopods appear with equal apparent suddenness in the older
+Mesozoic deposits, and no known type of the Palæozoic period can
+be pointed to as a possible ancestor. The <i>Hippuritidœ</i>
+of the Cretaceous burst into a varied life to all appearance
+almost immediately after their first introduction into existence.
+The wonderful Dicotyledonous flora of the Upper Cretaceous period
+similarly surprises us without any prophetic annunciation from
+the older Jurassic.
+</p>
+
+<p class="indent">
+Many other instances could be given; but enough has been said
+to show that there is a good deal to be said on both sides, and
+that the problem is one environed with profound difficulties.
+One point only seems now to be universally conceded, and that
+is, that the record of life in past time is not interrupted by
+gaps other than those due to the necessary imperfections of the
+fossiliferous series, to the fact that many animals are incapable
+of preservation in a fossil condition, or to other causes of a
+like nature. All those who are entitled to speak on this head
+are agreed that the introduction of new and the destruction of
+old species have been slow and gradual processes, in no sense of
+the term "catastrophistic." Most are also willing to admit that
+"Evolution" has taken place in the past, to a greater or less
+extent, and that a greater or less number of so-called species of
+fossil animals are really the modified descendants of pre-existent
+forms. <i>How</i> this process of evolution has
+<a name="page_374"><span class="page">Page 374</span></a>
+been effected, to what extent it has taken place, under what
+conditions and laws it has been carried out, and how far it may
+be regarded as merely auxiliary and supplemental to some deeper
+law of change and progress, are questions to which, in spite of
+the brilliant generalisations of Darwin, no satisfactory answer
+can as yet be given. In the successful solution of this
+problem&mdash;if soluble with the materials available to our
+hands&mdash;will lie the greatest triumph that Palæontology
+can hope to attain; and there is reason to think that, thanks to
+the guiding-clue afforded by the genius of the author of the
+'Origin of Species,' we are at least on the road to a sure,
+though it may be a far-distant, victory.
+</p>
+
+<h3>
+<a name="page_375"><span class="page">Page 375</span></a>
+APPENDIX.</h3>
+
+<hr />
+
+<p class="center">
+TABULAR VIEW OF THE CHIEF DIVISIONS OF THE ANIMAL KINGDOM.
+</p>
+
+<p class="center">
+(Extinct groups are marked with an asterisk. Groups not represented
+at all as fossils are marked with two asterisks.)
+</p>
+
+<h4>INVERTEBRATE ANIMALS.</h4>
+
+<p class="center">SUB-KINGDOM I.&mdash;PROTOZOA.</p>
+
+<p class="indent">
+Animal simple or compound; body composed of "sarcode," not definitely
+segmented; no nervous system; and no digestive apparatus, beyond
+occasionally a mouth and gullet.
+</p>
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>GREGARINIDÆ.**</td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>RHIZOPODA.</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>
+  <table border="0" cellspacing="0">
+   <tr>
+    <td valign="top" class="center"><i>Order</i></td>
+    <td>1. <i>Monera</i>.**</td>
+   </tr><tr>
+    <td valign="top" class="center"><i>&quot;</i></td>
+    <td>2. <i>Amœbea</i>.**</td>
+   </tr><tr>
+    <td valign="top" class="center"><i>&quot;</i></td>
+    <td>3. <i>Foraminifera</i>.</td>
+   </tr><tr>
+    <td valign="top" class="center"><i>&quot;</i></td>
+    <td>4. <i>Radiolaria</i> (Polycystines, &amp;c.)</td>
+   </tr><tr>
+    <td valign="top" class="center"><i>&quot;</i></td>
+    <td>5. <i>Spongida</i> (Sponges).</td>
+   </tr>
+  </table>
+ </td>
+</tr><tr>
+ <td>CLASS III.</td><td>INFUSORIA.**</td>
+</tr>
+</table>
+
+<p class="center">SUB-KINGDOM II.&mdash;CŒLENTERATA.</p>
+
+<p class="indent">
+Animal simple or compound; body-wall composed of two principal
+layers; digestive canal freely communicating with the general
+cavity of the body; no circulating organs, and no nervous system
+or a rudimentary one; mouth surrounded by tentacles, arranged,
+like the internal organs, in a "radiate" or star-like manner.
+</p>
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>HYDROZOA.</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>
+  <table border="0" cellspacing="0">
+   <tr><td valign="top"><i>Sub-class</i></td>
+    <td>1. <i>Hydroida</i> ("Hydroid Zoophytes"). <i>Ex.</i>
+     Fresh-water Polypes,** Pipe-corallines (<i>Tubularia</i>),
+     Sea-Firs (<i>Sertularia</i>).</td></tr>
+   <tr><td valign="top"><i>Sub-class</i></td>
+    <td>2. <i>Siphonophora</i>** ("Oceanic Hydrozoa").
+     <i>Ex</i>. Portuguese Man-of-war (<i>Physalia</i>).</td></tr>
+   <tr><td valign="top">
+<a name="page_376"><span class="page">Page 376</span></a>
+     <i>Sub-class</i></td>
+    <td>3. <i>Discophora</i> ("Jelly-fishes"). Only known as
+     fossils by impressions of their stranded carcasses.</td></tr>
+   <tr><td valign="top"><i>Sub-class</i></td>
+    <td>4. <i>Lucernarida</i> ("Sea-blubbers"). Also only known as
+     fossils by impressions left in fine-grained strata.</td></tr>
+   <tr><td valign="top"><i>Sub-class</i></td>
+    <td>5. <i>Graptolitidœ</i>* ("Graptolites").</td></tr>
+  </table>
+ </td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>ACTINOZOA.</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>
+  <table border="0" cellspacing="0">
+   <tr><td valign="top" class="center"><i>Order</i></td>
+    <td>1. <i>Zoantharia</i>. <i>Ex</i>. Sea-anemones**
+    (<i>Actinidœ</i>), Star-corals
+    (<i>Astrœidœ</i>).</td></tr>
+   <tr><td valign="top" class="center"><i>Order</i></td>
+    <td>2. <i>Alcyonaria</i>. <i>Ex</i>. Sea-pens
+     (<i>Pennatula</i>), Organ-pipe Coral (<i>Tubipora</i>),
+     Red Coral (<i>Corallium</i>).</td></tr>
+   <tr><td valign="top" class="center"><i>Order</i></td>
+    <td>3. <i>Rugosa</i> ("Rugose Corals").</td></tr>
+   <tr><td valign="top" class="center"><i>&quot;</i></td>
+    <td>4. <i>Ctenophora</i>.** <i>Ex</i>. Venus's Girdle
+     (<i>Cestum</i>).</td></tr>
+  </table>
+ </td>
+</tr>
+</table>
+
+<p class="center">SUB-KINGDOM III.&mdash;ANNULOIDA.</p>
+
+<p class="indent">
+Animals in which the digestive canal is completely shut off from
+the cavity of the body; a distinct nervous system; a system of
+branched "water-vessels," which usually communicate with the
+exterior. Body of the adult often "radiate," and never composed
+of a succession of definite rings.
+</p>
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>ECHINODERMATA.</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>
+  <table border="0" cellspacing="0">
+   <tr><td valign="top"><i>Order</i></td>
+    <td>1. <i>Crinoidea</i> ("Sea-lilies"). <i>Ex</i>.
+    Feather-star (<i>Comatula</i>), Stone-lily
+    (<i>Encrinus</i>*).</td></tr>
+   <tr><td valign="top"><i>Order</i></td>
+    <td>2. <i>Blastoidea</i>* ("Pentremites").</td></tr>
+   <tr><td valign="top" class="center"><i>"</i></td>
+    <td>3. <i>Cystoidea</i>* ("Globe-lilies").</td></tr>
+   <tr><td valign="top" class="center"><i>"</i></td>
+    <td>4. <i>Ophiuroidea</i> ("Brittle-stars").
+    <i>Ex</i>.</td></tr>
+   <tr><td valign="top" class="center"><i>"</i></td>
+    <td>Sand-stars (<i>Ophiura</i>), Brittle-stars
+    (<i>Ophiocoma</i>).</td></tr>
+   <tr><td valign="top"><i>Order</i></td>
+    <td>5. <i>Asteroidea</i> ("Star-fishes"). Ex. Cross-fish
+    (<i>Uraster</i>), Sun-star (<i>Solaster</i>).</td></tr>
+   <tr><td valign="top"><i>Order</i></td>
+    <td>6. <i>Echinoidea</i> ("Sea-urchins"). Ex. Sea-eggs
+    (<i>Echinus</i>), Heart-urchins (<i>Spatangus</i>).</td></tr>
+   <tr><td valign="top"><i>Order</i></td>
+    <td>7. <i>Holothuroidea</i> ("Sea-cucumbers"). <i>Ex</i>.
+    Trepangs (<i>Holothuria</i>).</td></tr>
+  </table>
+ </td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>SCOLECIDA** (Intestinal Worms, Wheel
+  Animalcules, &amp;c.)</td>
+</tr>
+</table>
+
+<p class="center">SUB-KINGDOM IV.&mdash;ANNULOSA.</p>
+
+<p class="indent">
+Animal composed of numerous definite segments placed one behind
+the other; nervous system forming a knotted cord placed along
+the lower (ventral) surface of the body.
+</p>
+
+<p class="center">
+<i>Division A. Anarthropoda</i>. No jointed limbs.
+</p>
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>GEPHYREA** ("Spoon-worms").</td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>ANNELIDA. ("Ringed-worms").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Leeches** (<i>Hirudinea</i>), Earthworms**
+  (<i>Oligochœta</i>), Tube-worms (<i>Tubicola</i>),
+  Sea-worms and Sea-centipedes (<i>Errantia</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;III.</td><td>CHÆTOGNATHA**
+  ("Arrow-worms").</td>
+</tr>
+</table>
+
+<p class="center">
+<i>Division B. Arthropoda or Articulata</i>. Limbs jointed to
+the body.
+</p>
+
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>CRUSTACEA ("Crustaceans").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Barnacles and Acorn-shells (<i>Cirripedia</i>),
+  Water-fleas (<i>Ostracoda</i>), Brine-shrimps and Fairy-shrimps
+  (<i>Phyllopoda</i>), Trilobites* (<i>Trilobita</i>), King-crabs
+  and Eurypterids* (<i>Merostomata</i>), Wood-lice and Slaters
+  (<i>Isopoda</i>), Sand-hoppers (<i>Amphipoda</i>), Lobsters,
+  Shrimps, Hermit-crabs, and Crabs (<i>Decapoda</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>
+<a name="page_377"><span class="page">Page 377</span></a>
+     ARACHNIDA.</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex.</i> Mites (<i>Acarina</i>), Scorpions
+ (<i>Pedipalpi</i>), Spiders (<i>Araneida</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;III.</td><td>MYRIAPODA.</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex.</i> Centipedes (<i>Chilopoda</i>), Millipedes and
+  Galley-worms (<i>Chilignatha</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;IV.</td><td>INSECTA ("Insects").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Field-bugs (<i>Hemiptera</i>); Crickets,
+  Grasshoppers, &amp;c. (<i>Orthoptera</i>); Dragon-flies and
+  May-flies (<i>Neuroptera</i>); Goats and House-flies
+  (<i>Diptera</i>); Butterflies and Moths (<i>Lepidoptera</i>);
+  Bees, Wasps, and Ants (<i>Hymenoptera</i>); Beetles
+  (<i>Coleoptera</i>).</td>
+</tr>
+</table>
+
+<p class="center">SUB-KINGDOM V.&mdash;MOLLUSCA.</p>
+
+<p class="indent">
+Animal soft-bodied, generally with a hard covering or shell; no
+distinct segmentation of the body; nervous system of scattered
+masses.
+</p>
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>POLYZOA ("Sea-Mosses").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Sea-mats (<i>Flustra</i>), Lace-corals
+  (<i>Fenestellidœ</i>*).</td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>TUNICATA** ("Tunicaries").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Sea-squirts (<i>Ascidia</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;III.</td><td>BRACHIOPODA ("Lamp-shells").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Goose-bill Lamp-shell (<i>Lingula</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;IV.</td><td>LAMELLIBRANCHIATA ("Bivalves").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Oyster (<i>Ostrea</i>), Mussel (<i>Mytilus</i>),
+  Scallop (<i>Pecten</i>), Cockle (<i>Cardium</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;V.</td><td>GASTEROPODA ("Univalves").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Whelks (<i>Buccinum</i>), Limpets
+  (<i>Patella</i>), Sea-slugs** (<i>Doris</i>), Land-snails
+  (<i>Helix</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;VI.</td><td>PTEROPODA ("Winged Snails").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>Ex. <i>Hyalea, Cleodora</i>.</td>
+</tr><tr>
+ <td>CLASS&nbsp;VII.</td><td>CEPHALOPODA ("Cuttle-fishes").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Calamary (<i>Loligo</i>), Poulpe (<i>Octopus</i>),
+  Paper Nautilus (<i>Arganauta</i>), Pearly Nautilus
+  (<i>Nautilus</i>), Belemnites,* Orthoceratites,*
+  Ammonites.*</td>
+</tr>
+</table>
+
+<h4>VERTEBRATE ANIMALS.</h4>
+
+<p class="center">SUB-KINGDOM VI.&mdash;VERTEBRATA.</p>
+
+<p class="indent">
+Body composed of definite segments arranged longitudinally one
+behind the other; main masses of the nervous system placed dorsally;
+a backbone or "vertebral column" in the majority.
+</p>
+
+<table border="0" cellspacing="0">
+<tr>
+ <td>CLASS&nbsp;I.</td><td>PISCES ("Fishes").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Lancelet** (<i>Amphioxus</i>); Lampreys and Hag-fishes
+  (<i>Marsipobranchii</i>**); Herring, Salmon, Perch, &amp;c.
+  (<i>Teleostei</i> or "Bony Fishes"); Gar-pike, Sturgeon, &amp;c.
+  (<i>Ganoidei</i>); Sharks, Dog-fishes, Rays, &amp;c.
+  (<i>Elasmobranchii</i> or "Placoids").</td>
+</tr><tr>
+ <td>CLASS&nbsp;II.</td><td>AMPHIBIA ("Amphibians").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>Ex. <i>Labyrinthodontia</i>,* Cæcilians,** Newts and
+  Salamanders (<i>Urodela</i>), Frogs and Toads (<i>Anoura</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;III.</td><td>REPTILIA ("Reptiles").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td>Ex. <i>Deinosauria</i>,* <i>Pterosauria</i>,* <i>Anomodontia</i>,*
+  Plesiosaurs (<i>Sauropterygia</i>*), Ichthyosaurs
+  (<i>Ichthyopterygia</i>*), Tortoises and Turtles (<i>Chelonia</i>),
+  Snakes (<i>Ophidia</i>), Lizards (<i>Lacertilia</i>), Crocodiles
+  (<i>Crocodilia</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;IV.</td><td>AVES ("Birds").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Toothed Birds (<i>Odontornithes</i>*); Lizard-tailed
+  Birds (<i>Archœopteryx</i>*); Ducks, Geese, Gulls, &amp;c.
+  (<i>Natatores</i>); Storks, Herons, Snipes, Plovers, &amp;c.
+  (<i>Grallatores</i>); Ostrich, Emeu, Cassowary, Dinornis,*
+  Æpiornis,* &amp;c. (<i>Cursores</i>); Fowls, Game Birds, and
+  Doves (<i>Rasores</i>); Cuckoos, Woodpeckers, Parrots, &amp;c.
+  (<i>Scansores</i>); Crows, Starlings, Finches, Hummingbirds,
+  Swallows, &amp;c. (<i>Insessores</i>); Owls, Hawks, Eagles, Vultures
+  (<i>Raptores</i>).</td>
+</tr><tr>
+ <td>CLASS&nbsp;V.</td><td>
+<a name="page_378"><span class="page">Page 378</span></a>
+  MAMMALIA ("Quadrupeds").</td>
+</tr><tr>
+ <td>&nbsp;</td>
+ <td><i>Ex</i>. Duck-mole and Spiny Ant-eater
+  (<i>Monotremata</i>**); Kangaroos, Phalangers, Opossums,
+  Tasmanian Devil, &amp;c. (<i>Marsupialia</i>); Sloths, Ant-eaters,
+  Armadillos (<i>Edentata</i>); Manatees and Dugongs
+  (<i>Sirenia</i>); Whales, Dolphins, Porpoises (<i>Cetacea</i>);
+  Rhinoceros, Tapir, Horses, Hippopotamus, Pigs, Camels and
+  Llamas, Giraffes, Deer, Antelopes, Sheep, Goats, Oxen
+  (<i>Ungulata</i>); Hyrax (<i>Hyracoidea</i>**); Elephants,
+  Mastodon,* Deinotherium* (<i>Proboscidea</i>); Seals,
+  Walrus, Bears, Dogs, Wolves, Cats, Lions, Tigers, &amp;c.
+  (<i>Carnivora</i>); Hares, Rabbits, Porcupines, Beavers,
+  Rats, Mice, Lemmings, Squirrels, Marmots, &amp;c. (<i>Rodentia</i>);
+  Bats (<i>Cheiroptera</i>); Moles, Shrew-mice, Hedgehogs
+  (<i>Insectivora</i>); Lemurs, Spider-monkeys, Macaques,
+  Baboons, Apes (<i>Quadrumana</i>); Man (<i>Bimana</i>).</td>
+</tr>
+</table>
+
+<h3>
+<a name="page_379"><span class="page">Page 379</span></a>
+GLOSSARY.</h3>
+
+<hr />
+
+<p>
+ABDOMEN (Lat. <i>abdo</i>, I conceal). The posterior cavity of
+the body, containing the intestines and others of the viscera. In
+many Invertebrates there is no separation of the body-cavity into
+thorax and abdomen, and it is only in the higher <i>Annulosa</i>
+that a distinct abdomen can be said to exist.<br/>
+ABERRANT (Lat. <i>aberro</i>, I wander away). Departing from the
+regular type.<br/>
+ABNORMAL (Lat. <i>ab</i>, from; <i>norma</i>, a rule). Irregular;
+deviating from the ordinary standard.<br/>
+ACRODUS (Gr. <i>akros</i>, high; <i>odous</i>, tooth). A genus
+of the Cestraciont fishes, so called from the elevated teeth.<br/>
+ACROGENS (Gr. <i>akros</i>, high; <i>gennao</i>, I produce).
+Plants which increase in height by additions made to the summit
+of the stem by the union of the bases of the leaves.<br/>
+ACROTRETA (Gr. <i>akros</i>, high; <i>tretos</i>, pierced). A
+genus of Brachiopods, so called from the presence of a foramen
+at the summit of the shell.<br/>
+ACTINOCRINUS (Gr. <i>aktin</i>, a ray; <i>krinon</i>, a lily).
+A genus of Crinoids.<br/>
+ACTINOZOA (Gr. <i>aktin</i>, a ray; and <i>zoön</i>, an animal).
+That division of the <i>Cœlenterata</i> of which the
+Sea-anemones may be taken as the type.<br/>
+ÆGLINA (<i>Æglé</i>, a sea-nymph). A genus of
+Trilobites.<br/>
+ÆPIORNIS (Gr. <i>aipus</i>, huge; <i>ornis</i>, bird). A genus
+of gigantic Cursorial birds.<br/>
+AGNOSTUS (Gr. <i>a</i>, not; <i>gignosko</i>, I know). A genus
+of Trilobites.<br/>
+ALCES (Lat. <i>alces</i>, elk). The European Elk or Moose.<br/>
+ALECTO (the proper name of one of the Furies). A genus of
+<i>Polyzoa</i>.<br/>
+ALETHOPTERIS (Gr. <i>alethes</i>, true; <i>pteris</i>, fern).
+A genus of Ferns.<br/>
+ALGÆ. (Lat. <i>alga</i>, a marine plant). The order of plants
+comprising the Sea-weeds and many fresh-water plants.<br/>
+ALVEOLUS (Lat. <i>alvus</i>, belly). Applied to the sockets of
+the teeth.<br/>
+AMBLYPTERUS (Gr. <i>amblus</i>, blunt; <i>pteron</i>, fin). An
+order of Ganoid Fishes.<br/>
+AMBONYCHIA (Gr. <i>ambon</i>, a boss; <i>onux</i>, claw). A genus
+of Palæozoic Bivalves.<br/>
+AMBULACRA (Lat. <i>ambulacrum</i>, a place for walking). The
+perforated spaces or "avenues" through which are protruded the
+tube-feet, by means of which locomotion is effected in the
+<i>Echinodermata</i>.<br/>
+AMMONITIDÆ. A family of Tetrabranchiate Cephalopods, so called
+from the resemblance of the shell of the type-genus, <i>Ammonites</i>,
+to the horns of the Egyptian God, Jupiter-Ammon.<br/>
+AMORPHOZOA (Gr. <i>a</i>, without; <i>morphe</i>, shape;
+<i>zoön</i>, animal). A name sometimes used to designate the
+<i>Sponges</i>.<br/>
+AMPHIBIA (Gr. <i>amphi</i>, both; <i>bios</i>, life). The Frogs,
+Newts, and the like, which have gills when young, but can always
+breathe air directly when adult.<br/>
+AMPHICYON (Gr. <i>amphi</i>, both&mdash;implying doubt; <i>kuon</i>,
+dog). An extinct genus of <i>Carnivora</i>.<br/>
+<a name="page_380"><span class="page">Page 380</span></a>
+AMPHILESTES (Gr. <i>amphi</i>, both; <i>lestes</i>, a thief). A
+genus of Jurassic Mammals.<br/>
+AMPHISPONGIA (Gr. <i>amphi</i>, both; <i>spoggos</i>, sponge).
+A genus of Silurian sponges.<br/>
+AMPHISTEGINA (Gr. <i>amphi</i>, both; <i>stegé</i>, roof). A
+genus of <i>Foraminifera</i>.<br/>
+AMPHITHERIUM (Gr. <i>amphi</i>, both; <i>therion</i>, beast).
+A genus of Jurassic Mammals.<br/>
+AMPHITRAGULUS (Gr. <i>amphi</i>, both; dim. of <i>tragos</i>,
+goat). An extinct genus related to the living Musk-deer.<br/>
+AMPLEXUS (Lat. an Ambrace). A genus of Rugose Corals.<br/>
+AMPYX (Gr. <i>ampux</i>, a wreath or wheel). A genus of
+Trilobites.<br/>
+ANARTHROPODA (Gr. <i>a</i>. without; <i>arthros</i>, a joint;
+<i>pous</i>, foot). That division of <i>Annulose</i> animals
+in which there are no articulated appendages.<br/>
+ANCHITHERIUM (Gr. <i>agchi</i>, near; <i>therion</i>, beast). An
+extinct genus of Mammals.<br/>
+ANCYLOCERAS (Gr. <i>agkulos</i>, crooked; <i>ceras</i>, horn).
+A genus of <i>Ammonitidœ</i>.<br/>
+ANCYLOTHERIUM (Gr. <i>agkulos</i>, crooked; <i>therion</i>, beast).
+An extinct genus of Edentate Mammals.<br/>
+ANDRIAS (Gr. <i>andrias</i>, image of man). An extinct genus of
+tailed Amphibians.<br/>
+ANGIOSPERMS (Gr. <i>angeion</i>, a vessel; <i>sperma</i>, seed).
+Plants which have their seeds enclosed in a seed-vessel.<br/>
+ANNELIDA (a Gallicised form of <i>Annulata</i>). The Ringed Worms,
+which form one of the divisions of the <i>Anarthropoda</i>.<br/>
+ANNULARIA (Lat. <i>annulus</i>, a ring). A genus of Palæozoic
+plants, with leaves in whorls.<br/>
+ANNULOSA (Lat. <i>annulus</i>). The sub-kingdom comprising the
+<i>Anarthropoda</i> and the <i>Arthropoda</i> or <i>Articulata</i>,
+in all of which the body is more or less evidently composed of
+a succession of rings.<br/>
+ANOMODONTIA (Gr. <i>anomos</i>, irregular; <i>odous</i>, tooth).
+An extinct order of Reptiles, often called <i>Dicynodontia</i>.<br/>
+ANOMURA (Gr. <i>anomos</i>, irregular; <i>oura</i>, tail). A
+tribe of Decapod <i>Crustacea</i>, of which the Hermit-crab is
+the type.<br/>
+ANOPLOTHERIDÆ (Gr. <i>anoplos</i>, unarmed; <i>ther</i>, beast).
+A family of Tertiary Ungulates.<br/>
+ANOURA (Gr. <i>a</i>, without; <i>oura</i>, tail). The order
+of <i>Amphibia</i> comprising the Frogs and Toads, in which the
+adult is destitute of a tail. Often, called <i>Batrachia</i>.<br/>
+ANTENNÆ (Lat. <i>antenna</i>, a yard-arm). The jointed horns
+or feelers possessed by the majority of the <i>Articulata</i>.<br/>
+ANTENNULES (dim. of <i>Antennœ</i>). Applied to the smaller
+pair of antennæ in the <i>Crustacea</i>.<br/>
+ANTHRACOSAURUS (Gr. <i>anthrax</i>, coal; <i>saura</i>, lizard).
+A genus of Labyrinthodont Amphibians.<br/>
+ANTHRAPALÆMON (Gr. <i>anthrax</i>, coal; <i>palœmon</i>, a
+prawn&mdash;originally a proper name). A genus of long-tailed
+Crustaceans from the Coal-measures.<br/>
+ANTLERS. Properly the branches of the horns of the Deer tribe
+(<i>Cervidœ</i>), but generally applied to the entire horns.<br/>
+APIOCRINIDÆ (Gr. <i>apion</i>, a pear; <i>krinon</i>, lily). A
+family of Crinoids&mdash;the "Pear-encrinites."<br/>
+APTERYX (Gr. <i>a</i>, without; <i>pterux</i>, a wing). A wingless
+bird of New Zealand, belong to the order <i>Cursores</i>.<br/>
+AQUEOUS (Lat. <i>aqua</i>, water). Formed in or by water.<br/>
+ARACHNIDA (Gr. <i>arachne</i>, a spider). A class of the
+<i>Articulata</i>, comprising Spiders, Scorpions, and allied
+animals.<br/>
+ARBORESCENT. Branched like a tree.<br/>
+ARCHÆOCIDARIS (Gr. <i>archaios</i>, ancient; Lat. <i>cidaris</i>,
+a diadem). A Palæozoic genus of Sea-urchins, related to the
+existing <i>Cidaris</i>.<br/>
+ARCHÆOCYATHUS (Gr. <i>archaios</i>, ancient; <i>kuathos</i>, cup).
+A genus of Palæozoic fossils allied to the Sponges.<br/>
+ARCHÆOPTERYX (Gr. <i>archaios</i>, ancient; <i>pterux</i>, a
+wing). The singular fossil bird which alone constitutes the order
+of the <i>Saururœ</i>.<br/>
+<a name="page_381"><span class="page">Page 381</span></a>
+ARCTOCYON (Gr. <i>arctos</i>, bear; <i>kuon</i>, dog). An extinct
+genus of Carnivora.<br/>
+ARENACEOUS. Sandy, or composed of grains of sand.<br/>
+ARENICOLITES (Lat. <i>arena</i>, sand; <i>colo</i>, I inhabit). A
+genus founded on burrows supposed to be formed by worms resembling
+the living Lobworms (<i>Arenicola</i>).<br/>
+ARTICULATA (Lat. <i>articulus</i>, a joint). A division of the
+animal kingdom, comprising Insects, Centipedes, Spiders, and
+Crustaceans, characterised by the possession of jointed bodies
+or jointed limbs. The term <i>Arthropoda</i> is now more usually
+employed.<br/>
+ARTIODACTYLA (Gr. <i>artios</i>, even; <i>daktulos</i>, a finger
+or toe). A division of the hoofed quadrupeds (<i>Ungulata</i>)
+in which each foot has an even number of toes (two or four).<br/>
+ASAPHUS (Gr. <i>Asaphes</i>, obscure). A genus of Trilobites.<br/>
+ASCOCERAS (Gr. <i>askos</i>, a leather bottle; <i>keras</i>, horn).
+A genus of Tetrabranchiate Cephalopods.<br/>
+ASIPHONATE. Not possessing a respiratory tube or siphon. (Applied
+to a division of the <i>Lamellibranchiate</i> Molluscs.)<br/>
+ASTEROID (Gr. <i>aster</i>, a star; and <i>eidos</i>, form).
+Star-shaped, or possessing radiating lobes or rays like a
+star-fish.<br/>
+ASTEROIDEA. An order of <i>Echinodermata</i>, comprising the
+Star-fishes, characterised by their rayed form.<br/>
+ASTEROPHYLLITES (Gr. <i>aster</i>, a star; <i>phullon</i>, leaf).
+A genus of Palæozoic plants, with leaves in whorls.<br/>
+ASTRÆIDÆ (Gr. <i>Astrœa</i>, a proper name).
+The family of the Star-corals.<br/>
+ASTYLOSPONGIA (Gr. <i>a</i>, without; <i>stulos</i>, a column;
+<i>spoggos</i>, a sponge). A genus of Silurian Sponges.<br/>
+ATHYRIS (Gr. <i>a</i>, without; <i>thura</i>, door). A genus of
+Brachiopods.<br/>
+ATRYPA (Gr. <i>a</i>, without; <i>trupa</i>, a hole). A genus
+of Brachiopods.<br/>
+AVES (Lat. <i>avis</i>, a bird). The class of the Birds.<br/>
+AVICULA (Lat. a little bird). The genus of Bivalve Molluscs
+comprising the Pearl-oysters.<br/>
+AXOPHYLLUM (Gr. <i>axon</i>, a pivot; <i>phullon</i>, a leaf).
+A genus of Rugose Corals.<br/>
+AZOIC (Gr. <i>a</i>, without; <i>zoé</i>, life). Destitute of
+traces of living beings.<br/>
+</p>
+
+<p>
+BACULITES (Lat. <i>baculum</i>, a staff). A genus of the
+<i>Ammonitidœ</i>.<br/>
+BALÆNA (Lat. a whale). The genus of the Whalebone Whales.<br/>
+BALANIDÆ (Gr. <i>balanos</i>, an acorn). A family of sessile
+<i>Cirripedes</i>, commonly called "Acorn-shells."<br/>
+BATRACHIA (Gr. <i>batrachos</i>, a frog). Often loosely applied
+to any of the <i>Amphibia</i>, but sometimes restricted to the
+Amphibians as a class, or to the single order of the
+<i>Anoura</i>.<br/>
+BELEMNITIDÆ (Gr. <i>belemnon</i>, a dart). An extinct group
+of Dibranchiate Cephalopods, comprising the Belemnites and their
+allies.<br/>
+BELEMNOTEUTHIS (Gr. <i>belemnon</i>, a dart; <i>teuthis</i>, a
+cuttle-fish). A genus allied to the Belemnites proper.<br/>
+BELINURUS (Gr. <i>belos</i>, a dart; <i>oura</i>, tail). A genus
+of fossil King-crabs.<br/>
+BELLEROPHON (Gr. proper name). A genus of oceanic Univalves
+(<i>Heteropoda</i>).<br/>
+BELOTEUTHIS (Gr. <i>belos</i>, a dart; <i>teuthis</i>, a
+cuttle-fish). An extinct genus of Dibranchiate Cephalopods.<br/>
+BEYRICHIA (named after Prof. Beyrich). A genus of Ostracode
+Crustaceans.<br/>
+BILATERAL. Having two symmetrical sides.<br/>
+BIMANA (Lat. <i>Bis</i>, twice; <i>manus</i>, a hand). The order
+of <i>Mammalia</i> comprising man alone.<br/>
+BIPEDAL (Lat. <i>bis</i>, twice; <i>pes</i>, foot). Walking upon
+two legs.<br/>
+BIVALVE (Lat. <i>bis</i>, twice; <i>valvœ</i>, folding-doors).
+Composed of two plates or valves; applied to the shell of the
+<i>Lamellibranchiata</i> and <i>Brachiopoda</i>, and to the
+carapace of certain <i>Crustacea</i>.<br/>
+BLASTOIDEA (Gr. <i>blastos</i>, a bud; and <i>eidos</i>, form).
+An extinct order of <i>Echinodermata</i>, often called
+<i>Pentremites</i>.<br/>
+BRACHIOPODA (Gr. <i>brachion</i>, an arm; <i>pous</i>, the foot).
+<a name="page_382"><span class="page">Page 382</span></a>
+A class or the <i>Molluscoida</i>, often called "Lamp-shells,"
+characterised by possessing two fleshy arms continued from the sides
+of the mouth.<br/>
+BRACHYURA (Gr. <i>brachus</i>, short; <i>oura</i>, tail). A tribe
+of the Decapod <i>Crustaceans</i> with short tails (<i>i.e.</i>,
+the Crabs).<br/>
+BRADYPODIDÆ. (Gr. <i>bradus</i>, slow; <i>podes</i>, feet). The
+family of <i>Edentata</i> comprising the Sloths.<br/>
+BRANCHIA (Gr. <i>bragchia</i>, the gill of a fish). A respiratory
+organ adapted to breathe air dissolved in water.<br/>
+BRANCHIATE. Possessing gills or branchiæ.<br/>
+BRONTEUS (Gr. <i>broné</i>, thunder&mdash;an epithet of Jupiter
+the Thunderer). A genus of Trilobites.<br/>
+BRONTOTHERIUM (Gr. <i>bronté</i>, thunder; <i>therion</i> beast).
+An extinct genus of Ungulate Quadrupeds.<br/>
+BRONTOZOUM (Gr. <i>bronté</i>, thunder; <i>zoön</i>, animal).
+A genus founded on the largest footprints of the Triassic Sandstones
+of Connecticut.<br/>
+BUCCINUM (Lat. <i>buccinun</i>, a trumpet). The genus of Univalves
+comprising the Whelks.
+</p>
+
+<p>
+CAINOZOIC (<i>See</i> Kainozoic.)<br/>
+CALAMITES (Lat. <i>calamus</i>, a reed). Extinct plants with
+reed-like stems, believed to be gigantic representatives of the
+<i>Equisetaceœ</i>.<br/>
+CALCAREOUS (Lat. <i>calx</i>, lime). Composed of carbonate of
+lime.<br/>
+CALICE. The little cup in which the polype of a coralligenous
+Zoophyte (<i>Actinozoön</i>) is contained.<br/>
+CALYMENE (Gr. <i>kalumené</i>, concealed). A genus of
+Trilobites.<br/>
+CALYX (Lat. a cup). Applied to the cup-shaped body of a
+<i>Crinoid</i> (<i>Echinodermata</i>).<br/>
+CAMAROPHORIA (Gr. <i>kamara</i>, a chamber; <i>phero</i>, I
+carry). A genus of Brachiopods.<br/>
+CAMELOPARDALIDÆ. (Lat. <i>camelus</i>, a camel;
+<i>pardalis</i>, a panther). The family of the Giraffes.<br/>
+CANINE (Lat. <i>canis</i>, a dog). The eye-tooth of Mammals,
+or the tooth which is placed at or close to the præmaxillary
+suture in the upper jaw, and the corresponding tooth in the lower
+jaw.<br/>
+CARAPACE. A protective shield. Applied to the upper shell of
+Crabs, Lobsters, and many other <i>Crustacea</i>. Also the upper
+half of the immovable case in which the body of a Chelonian is
+protected.<br/>
+CARCHARODON (Gr. <i>karcharos</i>. rough; <i>odous</i>, tooth).
+A genus of Sharks.<br/>
+CARDIOCARPON (Gr. <i>kardia</i>, the heart; <i>karpos</i>, fruit).
+A genus of fossil fruit from the Coal-measures.<br/>
+CARDIUM (Gr. <i>kardia</i>, the heart). The genus of Bivalve
+Molluscs comprising the Cockles. <i>Cardinia, Cardiola</i>, and
+<i>Cardita</i> have the same derivation.<br/>
+CARNIVORA (Lat. <i>caro</i>, flesh; <i>voro</i>, I devour). An
+order of the <i>Mammalia</i>. The "Beasts of Prey."<br/>
+CARNIVOROUS (Lat. <i>caro</i>, flesh; <i>voro</i>, I devour).
+Feeding upon flesh.<br/>
+CARYOCARIS (Gr. <i>karua</i>, a nut; <i>karis</i>, a shrimp).
+A genus of Phyllopod Crustaceans.<br/>
+CARYOCRINUS (Gr. <i>karua</i>, a nut; <i>krinon</i>, a lily).
+A genus of Cystideans.<br/>
+CAUDAL (Lat. <i>cauda</i>, the tail). Belonging to the
+tail.<br/>
+CAVICORNIA (Lat. <i>cavus</i>, hollow; <i>cornu</i>, a horn).
+The "hollow-horned" Ruminants, in which the horn consists of
+a central bony "horn-core" surrounded by a horny sheath.<br/>
+CENTRUM (Gr. <i>kentron</i>, the point round which a circle is
+described by a pair of compasses). The central portion or "body"
+of a vertebra.<br/>
+CEPHALASPIDÆ. (Gr. <i>kephale</i>, head; <i>aspis</i>,
+shield). A family of fossil fishes.<br/>
+CEPHALIC (Gr. <i>kephale</i>, head). Belonging to the head.<br/>
+CEPHALOPODA (Gr. <i>kephale</i>; and <i>podes</i>, feet). A class
+of the <i>Mollusca</i>, comprising the Cuttle-fishes and their
+allies, in which there is a series of arms ranged round the
+head.<br/>
+CERATIOCARIS (Gr. <i>keras</i>, a horn; <i>karis</i>, a shrimp).
+A genus of Phyllopod Crustaceans.<br/>
+<a name="page_383"><span class="page">Page 383</span></a>
+CERATITES (Gr. <i>keras</i>, a horn). A genus
+of <i>Ammonitidœ</i>.<br/>
+CERATODUS (Gr. <i>keras</i>, a horn; <i>odous</i>, tooth). A
+genus of Dipnoous fishes.<br/>
+CERVICAL (Lat. <i>cervix</i>, the neck). Connected with or
+belonging to the region of the neck.<br/>
+CERVIDÆ (Lat. <i>cervus</i>, a stag). The family of the
+Deer.<br/>
+CESTRAPHORI (Gr. <i>kestra</i>, a weapon; <i>phero</i>, I carry).
+The group of the "Cestraciont Fishes," represented at the present
+day by the Port-Jackson Shark; so called from their defensive
+spines.<br/>
+CETACEA (Gr. <i>ketos</i>, a whale). The order of Mammals
+comprising the Whales and the Dolphins.<br/>
+CETIOSAURUS (Gr. <i>ketos</i>, whale; <i>saura</i>, lizard). A
+genus of Deinosaurian Reptiles.<br/>
+CHEIROPTERA (Gr. <i>cheir</i>, hand; <i>pteron</i>, wing). The
+Mammalian order of the Bats.<br/>
+CHEIROTHERIUM (Gr. <i>cheir</i>, hand; <i>therion</i>, beast).
+The generic name applied originally to the hand-shaped footprints
+of Labyrinthodonts.<br/>
+CHEIRURUS (Gr. <i>cheir</i>, hand; <i>oura</i>, tail). A genus
+of Trilobites.<br/>
+CHELONIA (Gr. <i>cheloné</i>, a tortoise). The Reptilian
+order of the Tortoises and Turtles.<br/>
+CHONETES (Gr. <i>choné</i> or <i>choané</i>, a
+chamber or box). A genus of Brachiopods.<br/>
+CIDARIS (Lat. a diadem). A genus of Sea-urchins.<br/>
+CLADODUS (Gr. <i>klados</i>, branch; <i>odous</i>, tooth). A genus
+of Fishes.<br/>
+CLATHROPORA (Lat. <i>clathti</i>, a trellis; <i>porus</i>, a pore).
+A genus of Lace-corals (<i>Polyzoa</i>).<br/>
+CLISIOPHYLLUM (Gr. <i>klision</i>, a hut; <i>phullon</i>, leaf).
+A genus of Rugose Corals.<br/>
+CLYMENIA (<i>Clumene</i>, a proper name). A genus of
+Tetrabranchiate Cephalopods.<br/>
+COCCOSTEUS (Gr. <i>kokkos</i>, berry; <i>osteon</i>, bone). A
+genus of Ganoid Fishes.<br/>
+COCHLIODUS (Gr. <i>kochlion</i>, a snail-shell; <i>odous</i>,
+tooth). A genus of Cestraciont Fishes.<br/>
+CŒLENTERATA (Gr. <i>koilos</i>, hollow; <i>enteron</i>, the
+bowel). The sub-kingdom which comprises the <i>Hydrozoa</i> and
+<i>Actinozoa</i>. Proposed by Frey and Leuckhart in place of the
+old term <i>Radiata</i>, which included other animals as
+well.<br/>
+COLEOPTERA (Gr. <i>koleos</i>, a sheath; <i>pteron</i>, wing).
+The order of Insects (Beetles) in which the anterior pair of wings
+are hardened, and serve as protective cases for the posterior
+pair of membranous wings.<br/>
+COLOSSOCHELYS (Gr. <i>kolossos</i>, a gigantic statue; <i>chelus</i>,
+a tortoise). A huge extinct Land-tortoise.<br/>
+COMATULA (Gr. <i>koma</i>, the hair). The Feather-star, so called
+in allusion to its tress-like arms.<br/>
+CONDYLE (Gr. <i>kondulos</i>, a knuckle). The surface by which
+one bone articulates with another. Applied especially to the
+articular surface or surfaces by which the skull articulates with
+the vertebral column.<br/>
+CONIFERÆ (Lat. <i>conus</i>, a cone; <i>fero</i>, I carry).
+The order of the Firs, Pines, and their allies, in which the
+fruit is generally a "cone" or "fir-apple."<br/>
+CONULARIA (Lat. <i>conulus</i>, a little-cone). An extinct genus
+of Pteropods.<br/>
+COPRALITES (Gr. <i>kopros</i>, dung; <i>lithos</i>, stone). Properly
+applied to the fossilised excrements of animals; but often employed
+to designate phosphatic concretions which are not of this
+nature.<br/>
+CORALLITE. The corallum secreted by an <i>Actinozoön</i> which
+consists of a single polype; or the portion of a composite corallum
+which belongs to, and is secreted by, an individual polype.<br/>
+CORALLUM (from the Latin for Red Coral). The hard structures
+deposited in, or by the tissues of an
+<i>Actinozoön</i>,&mdash;commonly called a "coral."<br/>
+CORIACEOUS (Lat. <i>corium</i>. hide). Leathery.<br/>
+CORYPHODON (Gr. <i>korus</i>, helmet; <i>odous</i>, tooth). An
+extinct genus of Mammals, allied to the Tapirs.<br/>
+CRANIUM (Gr. <i>kranion</i>, the skull). The bony or cartilaginous
+case in which the brain is contained.<br/>
+CRETACEOUS (Lat. <i>creta</i>, chalk). The formation which in
+Europe contains white chalk as one of its most conspicuous
+members.<br/>
+<a name="page_384"><span class="page">Page 384</span></a>
+CRINOIDEA (Gr. <i>krinon</i>, a lily; <i>eidos</i>, form). An order
+of <i>Echinodermata</i>, comprising forms which are usually stalked,
+and sometimes resemble lilies in shape.<br/>
+CRIOCERAS (Gr. <i>krios</i>, a ram; <i>keras</i>, a horn). A genus
+of <i>Ammonitidœ</i>.<br/>
+CROCODILIA (Gr. <i>krokodeilos</i>, a crocodile). An order of
+Reptiles.<br/>
+CROSSOPTERYGIDÆ. (Gr. <i>krossotos</i>, a fringe;
+<i>pterux</i>, a fin). A sub-order of Ganoids in which the paired
+fins possess a central lobe.<br/>
+CRUSTACEA (Lat. <i>crusta</i>, a crust). A class of Articulate
+animals, comprising Crabs, Lobsters, &amp;c., characterised by the
+possession of a hard shell or crust, which they cast
+periodically.<br/>
+CRYPTOGAMS (Gr. <i>kruptos</i>, concealed; <i>gamos</i>, marriage).
+A division of plants in which the organs of reproduction are
+obscure and there are no true flowers.<br/>
+CTENACANTHUS (Gr. <i>kteis</i>, a comb; <i>akantha</i>, a thorn).
+A genus of fossil fishes, named from its fin-spines.<br/>
+CTENOID (Gr. <i>kteis</i>, a comb; <i>eidos</i>, form). Applied
+to those scales of fishes the hinder margins of which are fringed
+with spines or comb-like projections.<br/>
+CURSORES (Lat. <i>curro</i>, I run). An order of <i>Aves</i>,
+comprising birds destitute of the power of flight, but formed
+for running vigorously (<i>e.g.</i>, the Ostrich and Emeu).<br/>
+CUSPIDATE. Furnished with small pointed eminences or "cusps."<br/>
+CYATHOCRINUS (Gr. <i>kuathos</i>, a cup; <i>krinon</i>, a lily).
+A genus of Crinoids.<br/>
+CYATHOPHYLLUM (Gr. <i>kuathos</i>, a cup; <i>phullon</i>, a leaf).
+A genus of Rugose Corals.<br/>
+CYCLOID (Gr. <i>kuklos</i>, a circle; <i>eidos</i>, form). Applied
+to those scales of fishes which have a regularly circular or
+elliptical outline with an even margin.<br/>
+CYCLOPHTHALMUS (Gr. <i>kuklos</i>, a circle; <i>ophthalmos</i>,
+eye). A genus of fossil Scorpions.<br/>
+CYCLOSTOMI (Gr. <i>kuklos</i>, and <i>stoma</i>, mouth). Sometimes
+used to designate the Hag-fishes and Lampreys, forming the order
+<i>Marsipobranchii</i>.<br/>
+CYPRÆA (a name of Venus). The genus of Univalve Molluscs
+comprising the Cowries.<br/>
+CYRTOCERAS (Gr. <i>kurtos</i>. crooked; <i>keras</i>, horn). A
+genus of Tetrabranchiate Cephalopods.<br/>
+CYSTIPHYLLUM (Gr. <i>kustis</i>, a bladder; <i>phullon</i>, a
+leaf). A genus of Rugose Corals.<br/>
+CYSTOIDEA (Gr. <i>kustis</i>, a bladder; <i>eidos</i>, form).
+The "Globe-crinoids," an extinct order of
+<i>Echinodermata</i>.
+</p>
+
+<p>
+DADOXYLON (Gr. <i>dadion</i>, a torch; <i>xulon</i>, wood). An
+extinct genus of Coniferous trees.<br/>
+DECAPODA (Gr. <i>deka</i>, ten; <i>podes</i>, feet). The division
+of <i>Crustacea</i> which have ten feet; also the family of
+Cuttle-fishes, in which there are ten arms or cephalic
+processes.<br/>
+DECIDUOUS (Lat. <i>decido</i>, I fall off). Applied to parts which
+fall off or are shed during the life of the animal.<br/>
+DEINOSAURIA (Gr. <i>deinos</i>, terrible; <i>saura</i>, lizard).
+An extinct order of Reptiles.<br/>
+DEINOTHERIUM (Gr. <i>deinos</i>, terrible; <i>therion</i>, beast).
+An extinct genus of Proboscidean Mammals.<br/>
+DENDROGRAPTUS (Gr. <i>dendron</i>, tree; <i>grapho</i>, I write).
+A genus of Graptolites.<br/>
+DESMIDIÆ. Minute fresh-water plants, of a green colour, without
+a siliceous epidermis.<br/>
+DIATOMACEÆ (Gr. <i>diatemno</i>, I sever). An order of minute
+plants which are provided with siliceous envelopes.<br/>
+DIBRANCHIATA (Gr. <i>dis</i>; twice; <i>bragchia</i>, gill).
+The order of <i>Cephalopoda</i> (comprising the Cuttle-fishes,
+&amp;c.) in which only two gills are present.<br/>
+DICERAS (Gr. <i>dis</i>, twice; <i>keras</i>, horn). An extinct
+genus of Bivalve Molluscs.<br/>
+DICTYONEMA (Gr. <i>diktuon</i>, a net; <i>nema</i>, thread). An
+extinct genus of <i>Polyzoa</i>.<br/>
+<a name="page_385"><span class="page">Page 385</span></a>
+DICYNODONTIA (Gr. <i>dis</i>, twice; <i>kuon</i>, dog; <i>odous</i>,
+tooth). An extinct order of Reptiles.<br/>
+DIDYMOGRAPTUS (Gr. <i>didumos</i>, twin; <i>grapho</i>, I write).
+A genus of Graptolites.<br/>
+DIMORPHODON (Gr. <i>dis</i>, twice; <i>morphé</i>, shape;
+<i>oduos</i>, tooth). A genus of Pterosaurian reptiles.<br/>
+DINICHTHYS (Gr. <i>deinos</i>, terrible; <i>ichthus</i>, fish).
+An extinct genus of Fishes.<br/>
+DINOCERAS (Gr. <i>deinos</i>, terrible; <i>keras</i>, horn). An
+extinct genus of Mammals.<br/>
+DINOPHIS (Gr. <i>deinos</i>, terrible; <i>ophis</i>, snake). An
+extinct genus of Snakes.<br/>
+DINORNIS (Gr. <i>deinos</i>, terrible; <i>ornis</i>, bird). An
+extinct genus of Birds.<br/>
+DIPLOGRAPTUS (Gr. <i>diplos</i>, double; <i>grapho</i>, I write).
+A genus of Graptolites.<br/>
+DIPNOI (Gr. <i>dis</i>, twice; <i>pnoé</i>, breath). An order
+of Fishes, comprising the Mud-fishes, so called in allusion to
+their double mode of respiration.<br/>
+DIPROTODON (Gr. <i>dis</i>, twice; <i>protos</i>, first;
+<i>odous</i>, tooth). A genus of extinct Marsupials.<br/>
+DIPTERA (Gr. <i>dis</i>, twice; <i>pteron</i>, wing). An order
+of Insects characterised by the possession of two wings.<br/>
+DISCOID (Gr. <i>diskos</i>, a quoit; <i>eidos</i>, form). Shaped
+like a round plate or quoit.<br/>
+DOLOMITE (named after M. Dolomieu). Magnesian limestone.<br/>
+DORSAL (Lat. <i>dorsum</i>, the back). Connected with or placed
+upon the back.<br/>
+DROMATHERIUM (Gr. <i>dromaios</i>, nimble; <i>therion</i>, beast).
+A genus of Triassic Mammals.<br/>
+DRYOPITHECUS (Gr. <i>drus</i>, an oak; <i>pithekos</i>, an ape).
+An extinct genus of Monkeys.
+</p>
+
+<p>
+ECHINODERMATA (Gr. <i>echinos</i>; and <i>derma</i>, skin). A
+class of animals comprising the Sea-urchins, Star-fishes, and
+others, most of which have spiny skins.<br/>
+ECHINOIDEA (Gr. <i>echinos</i>; and <i>eidos</i>, form). An order
+of <i>Echinodermata</i>, comprising the Sea-urchins.<br/>
+EDENTATA (Lat. <i>e</i>, without; <i>dens</i>, tooth). An order
+of <i>Mammalia</i> often called <i>Bruta</i>.<br/>
+EDENTULOUS. Toothless, without any dental apparatus. Applied to
+the mouth of any animal, or to the hinge of the Bivalve
+Molluscs.<br/>
+ELASMOBRANCHII (Gr. <i>elasma</i>, a plate; <i>bragchia</i>, gill).
+An order of Fishes, including the Sharks and Rays.<br/>
+ENALIOSAURIA (Gr. <i>enalios</i>, marine; <i>saura</i>, lizard),
+Sometimes employed as a common term to designate the extinct
+Reptilian orders of the <i>Ichthyosauria</i> and
+<i>Plesiosauria</i>.<br/>
+EOCENE (Gr. <i>eos</i>, dawn; <i>kainos</i>, new or recent).
+The lowest division of the Tertiary rocks, in which species of
+existing shells are to a small extent represented.<br/>
+EOPHYTON (Gr. <i>eos</i>, dawn; <i>phuton</i>, a plant). A genus
+of Cambrian fossils, supposed to be of a vegetable nature.<br/>
+EOZO&Ouml;N (Gr. <i>eos</i>, dawn; <i>zoön</i>, animal). A
+genus of chambered calcareous organisms found in the Laurentian and
+Huronian formations.<br/>
+EQUILATERAL (Lat. <i>œquus</i>, equal; <i>latus</i>, side).
+Having its sides equal. Usually applied to the shells of the
+<i>Brachiopoda</i>. When applied to the spiral shells of the
+<i>Foraminifera</i>, it means that all the convolutions of the
+shell lie in the same plane.<br/>
+EQUISETACEÆ (Lat. <i>equus</i>, horse; <i>seta</i>, bristle). A
+group of Cryptogamous plants, commonly known as "Horse-tails."<br/>
+EQUIVALVE (Lat. <i>œquus</i>, equal; <i>valvœ</i>,
+folding-doors). Applied to shells which are composed of two equal
+pieces or valves.<br/>
+ERRANTIA (Lat. <i>erro</i>, I wander). An order of <i>Annelida</i>,
+often called <i>Nereidea</i>, distinguished by their great locomotive
+powers.<br/>
+EUOMPHALUS (Gr. <i>eu</i>, well; <i>omphalos</i>, navel). An extinct
+genus of Univalve Molluscs.<br/>
+EURYPTERIDA (Gr. <i>eurus</i>, broad; <i>pteron</i>, wing). An
+extinct sub-order of <i>Crustacea</i>.<br/>
+EXOGYRA (Gr. <i>exo</i>, outside; <i>guros</i>, circle). An extinct
+genus of Oysters.
+</p>
+
+<p>
+<a name="page_386"><span class="page">Page 386</span></a>
+FAUNA (Lat. <i>Fauni</i>, the rural deities of the Romans). The
+general assemblage of the animals of any region or district.<br/>
+FAVOSITES (Lat. <i>favus</i>, a honeycomb). A genus of Tabulate
+Corals.<br/>
+FENESTELLIDÆ. (Lat. <i>fenestella</i>, a little window). The
+"Lace-corals," a group of Palæozoic Polyzoans.<br/>
+FILICES (Lat. <i>filix</i>, a fern). The order of Cryptogamic
+plants comprising the Ferns.<br/>
+FILIFORM (Lat. <i>filum</i>, a thread; <i>forma</i>, shape).
+Thread-shaped.<br/>
+FLORA (Lat. <i>Flora</i>, the goddess of flowers). The general
+assemblage of the plants of any region or district.<br/>
+FORAMINIFERA (Lat. <i>foramen</i>, an aperture; <i>fero</i>,
+I carry). An order of Protozoa, usually characterised by the
+possession of a shell perforated by numerous pseudopodial
+apertures.<br/>
+FRUGIVOROUS (Lat. <i>frux</i>, fruit; <i>voro</i>, I devour).
+Living upon fruits.<br/>
+FUCOIDS (Lat. <i>fucus</i>, sea-weed; Gr. <i>eidos</i>, likeness).
+Fossils, often of an obscure nature, believed to be the remains
+of sea-weeds.<br/>
+FUSULINA (Lat. <i>fusus</i>, a spindle). An extinct genus of
+<i>Foraminifera</i>.<br/>
+</p>
+
+<p>
+GANOID (Gr, <i>ganos</i>, splendour, brightness). Applied to
+those scales or plates which are composed of an inferior layer
+of true bone covered by a superior layer of polished enamel.<br/>
+GANOIDEI. An order of Fishes.<br/>
+GASTEROPODA (Gr. <i>gaster</i>, stomach; <i>pous</i>, foot).
+The class of the Mollusca comprising the ordinary Univalves,
+in which locomotion is usually effected by a muscular expansion
+of the under surface of the body (the "foot").<br/>
+GLOBIGERINA (Lat. <i>globus</i>, a globe; <i>gero</i>, I carry).
+A genus of <i>Foraminifera</i>.<br/>
+GLYPTODON (Gr. <i>glupho</i>, I engrave; <i>odous</i>, tooth). An
+extinct genus of Armadillos, so named in allusion to the fluted
+teeth.<br/>
+GONIATITES (Gr. <i>gonia</i>, angle). A genus of Tetrabranchiate
+Cephalopods.<br/>
+GRALLATORES (Lat. <i>grallœ</i>, stilts). The order of the
+long-legged Wading Birds.<br/>
+GRAPTOLITIDÆ. (Gr. <i>grapho</i>, I write; <i>lithos</i>,
+stone). An extinct sub-class of the <i>Hydrozoa</i>.<br/>
+GYMNOSPERMS (Gr. <i>gumnos</i>, naked; <i>sperma</i>, seed). The
+Conifers and Cycads, in which the seed is not protected within
+a seed-vessel.
+</p>
+
+<p>
+HALITHERIUM (Gr. <i>hals</i>, sea; <i>therion</i>, beast). An
+extinct genus of Sea-cows (<i>Sirenia</i>).<br/>
+HAMITES (Lat. <i>hamus</i>, a hook). A genus of the
+<i>Ammonitidœ</i>.<br/>
+HELIOPHYLLUM (Gr. <i>helios</i>, the sun; <i>phullon</i>, leaf).
+A genus of Rugose Corals.<br/>
+HELLADOTHERIUM (Gr. <i>Hellas</i>, Greece; <i>therion</i>, beast).
+An extinct genus of Ungulate Mammals.<br/>
+HEMIPTERA (Gr. <i>hemi</i>, and <i>pteron</i>, wing). An order
+of Insects in which the anterior wings are sometimes
+"hemelytra."<br/>
+HESPERORNIS (Gr. <i>Hesperos</i>, the evening star; <i>ornis</i>,
+bird). An extinct genus of Birds.<br/>
+HETEROCERCAL (Gr. <i>heteros</i>, diverse; <i>kerkos</i>, tail).
+Applied to the tail of Fishes when it is unsymmetrical, or composed
+of two unequal lobes.<br/>
+HETEROPODA (Gr. <i>heteros</i>, diverse; <i>podes</i>, feet). An
+aberrant group of the Gasteropods, in which the foot is modified
+so as to form a swimming organ.<br/>
+HIPPARION (Gr. <i>hipparion</i>, a little horse). An extinct genus
+of <i>Equidœ</i>.<br/>
+HIPPOPOTAMUS (Gr. <i>hippos</i>, horse; <i>potamos</i>, river).
+A genus of Hoofed Quadrupeds&mdash;the "River-horses."<br/>
+HIPPURITIDÆ. (Gr. <i>hippos</i>, horse; <i>oura</i>, tail). An
+extinct family of Bivalve Molluscs.<br/>
+HOLOPTYCHIUS (Gr. <i>holos</i>, whole; <i>ptucé</i>, wrinkle).
+An extinct genus of Ganoid Fishes.<br/>
+HOLOSTOMATA (Gr. <i>holos</i>, whole; <i>stoma</i>, mouth). A
+division of <i>Gasteropodous Molluscs</i>, in which the aperture
+of the shell is rounded, or "entire."<br/>
+HOLOTHUROIDEA (Gr. <i>holothourion</i>, and <i>eidos</i>, form).
+An order of <i>Echinodermata</i> comprising the Trepangs.<br/>
+<a name="page_387"><span class="page">Page 387</span></a>
+HOMOCERCAL (Gr. <i>homos</i>, same; <i>kerkol</i>, tail). Applied
+to the tail of Fishes when it is symmetrical, or composed of two
+equal lobes.<br/>
+HYBODUNTS (Gr. <i>hubos</i>, curved; <i>odous</i>, tooth). A group
+of Fishes of which <i>Hybodus</i> is the type-genus.<br/>
+HYDROIDA (Gr. <i>hudra</i>; and <i>eidos</i>, form). The sub-class
+of the <i>Hydrozoa</i>, which comprises the animals most nearly
+allied to the Hydra.<br/>
+HYDROZOA (Gr. <i>hudra</i>; and <i>zoön</i>, animal). The class
+of the <i>Cœlenterata</i> which comprises animals constructed
+after the type of the Hydra.<br/>
+HYMENOPTERA (Gr. <i>humen</i>, a membrane; <i>pteron</i>, a wing).
+An order of Insects (comprising Bees, Ants, &amp;c.) characterised
+by the possession of four membranous wings.
+</p>
+
+<p>
+ICHTHYODORULITE (Gr. <i>ichthus</i>, fish; <i>dorus</i>, spear;
+<i>lithos</i>, stone). The fossil fin-spine of Fishes.<br/>
+ICHTHYOPTERYGIA (Gr. <i>ichthus</i>; <i>pterux</i>, wing). An
+extinct order of Reptiles.<br/>
+ICHTHYORNIS (Gr. <i>ichthus</i>, fish; <i>ornis</i>, bird). An
+extinct genus of Birds.<br/>
+ICHTHYOSAURIA (Gr. <i>ichthus</i>; <i>saura</i>, lizard). Synonymous
+with <i>Ichthyopterygia</i>.<br/>
+IGUANODON (<i>Iguana</i>, a living lizard; Gr. <i>odous</i>, tooth).
+A genus of Deinosaurian Reptiles.<br/>
+INCISOR (Lat. <i>incido</i>, I cut). The cutting teeth fixed
+in the intermaxillary bones of the <i>Mammalia</i>, and the
+corresponding teeth in the lower jaw.<br/>
+INEQUILATERAL. Having the two sides unequal, as in the case of
+the shells of the ordinary bivalves (<i>Lamellibranchiata</i>).
+When applied to the shells of the <i>Foraminifera</i>, it implies
+that the convolutions of the shell do not lie in the same plane,
+but are obliquely wound round an axis.<br/>
+INEQUIVALVE. Composed of two unequal pieces or valves.<br/>
+INOCERAMUS (Gr. <i>is</i>, a fibre; <i>keramos</i>, an earthen
+vessel). An extinct genus of Bivalve Molluscs.<br/>
+INSECTA (Lat. <i>inseco</i>, I cut into). The class of articulate
+animals commonly known as Insects.<br/>
+INSECTIVORA (Lat. <i>insectum</i>, an insect; <i>voro</i>, I
+devour). An order of Mammals.<br/>
+INSECTIVOROUS. Living upon Insects.<br/>
+INSESSORES (Lat. <i>insedeo</i>, I sit upon). The order of the
+Perching Birds, often called <i>Passeres</i>.<br/>
+INTERAMBULACRA. The rows of plates in an <i>Echinoid</i> which
+are not perforated for the emission of the "tube-feet."<br/>
+INTERMMAXILLÆ or PRÆMAXILLÆ. The two bones
+which are situated between the two superior maxillæ in
+<i>Vertebrata</i>. In man, and some monkeys, the
+præmaxillæ anchylose with the maxillæ, so
+as to be irrecognisable in the adult.<br/>
+INVERTEBRATA (Lat. <i>in</i>, without; <i>vertebra</i>, a bone
+of the back). Animals without a spinal column or backbone.<br/>
+ISOPODA. (Gr. <i>isos</i>, equal; <i>podes</i>, feet). An order
+of <i>Crustacea</i> in which the feet are like one another and
+equal.
+</p>
+
+<p>
+KAINOZOIC (Gr. <i>kainos</i>, recent; <i>zoe</i>, life). The
+Tertiary period in Geology comprising those formations in which
+the organic remains approximate more or less closely to the existing
+fauna and flora.
+</p>
+
+<p>
+LABYRINTHODONTIA (Gr. <i>laburinthos</i>, a labyrinth; <i>odous</i>,
+tooth). An extinct order of <i>Amphibia</i>, so called from the
+complex microscopic structure of the teeth.<br/>
+LACERTILIA (Lat. <i>lacerta</i>, a lizard). An order of
+<i>Reptilia</i> comprising the Lizards and Slow-worms.<br/>
+LAMELLIBRANCHIATA (Lat. <i>lamella</i>, a plate; Gr. <i>bragchia</i>,
+gill). The class of <i>Mollusca</i> comprising the ordinary bivalves,
+characterised by the possession of lamellar gills.<br/>
+LEPIDODENDRON (Gr. <i>lepis</i>, a scale; <i>dendron</i>, a tree).
+A genus of extinct plants, so named from the scale-like scars
+upon the stem left by the falling off of the leaves.<br/>
+<a name="page_388"><span class="page">Page 388</span></a>
+LEPIDOPTERA (Gr. <i>lepis</i>, a scale; <i>pteron</i>, a wing). An
+order of Insects, comprising Butterflies and Moths, characterised by
+possessing four wings which are usually covered with minute scales.<br/>
+LEPIDOSIREN (Gr. <i>lepis</i>, a scale; <i>seiren</i>, a
+siren&mdash;the generic name of the Mud-eel or <i>Siren
+lacertina</i>). A genus of Dipnoous fishes, comprising the
+"Mud-fishes."<br/>
+LEPIDOSTROBUS (Gr. <i>lepis</i>, a scale; <i>strobilos</i>, a
+fir-cone). A genus founded on the cones of <i>Lepidodendron</i>.<br/>
+LEPTÆNA (Gr. <i>leptos</i>. slender). A genus of
+Brachiopods.<br/>
+LINGULA (Lat. <i>lingula</i>, a little tongue). A genus of
+Brachiopods.<br/>
+LYCOPODIACEÆ (Gr. <i>lupos</i>, a wolf; <i>pous</i>, foot). The
+group of Cryptogamic plants generally known as "Club-mosses."
+</p>
+
+<p>
+MACHÆRACANTHUS (Gr. <i>machaira</i>, a sabre; <i>acantha</i>,
+thorn or spine). An extinct genus of Fishes.<br/>
+MACHAIRODUS (Gr. <i>machaira</i>, a sabre; <i>odous</i>, tooth).
+An extinct genus of Carnivora.<br/>
+MACROTHERIUM (Gr. <i>makros</i>, long; <i>therion</i>. beast).
+An extinct genus of Edentata.<br/>
+MACRURA (Gr. <i>makros</i>, long; <i>oura</i>, tail). A tribe of
+Decapod <i>Crustaceans</i> with long tails (e.g., the Lobster,
+Shrimp, &amp;c.)<br/>
+MAMMALIA (Lat. <i>mamma</i>, the breast). The class of Vertebrate
+animals which suckle their young.<br/>
+MANDIBLE (Lat. <i>mandibulum</i>, a jaw). The upper pair of jaws
+in Insects; also applied to one of the pairs of jaws in
+<i>Crustacea</i> and Spiders, to the beak of Cephalopods, the
+lower jaw of Vertebrates, &amp;c.<br/>
+MANTLE. The external integument of most of the Mollusca, which
+is largely developed, and forms a cloak in which the viscera
+are protected. Technically called the "pallium."<br/>
+MANUS (Lat. the hand). The hand of the higher Vertebrates.<br/>
+MARSIPOBRANCHII (Gr. <i>marsipos</i>, a pouch; <i>bragchia</i>,
+gill). The order of Fishes comprising the Hag-fishes and Lampreys,
+with pouch-like gills.<br/>
+MARSUPIALIA (Lat. <i>marsupium</i>, a pouch). An order of Mammals
+in which the females mostly have an abdominal pouch in which
+the young are carried.<br/>
+MASTODON (Gr. <i>mastos</i>, nipple; <i>odous</i>, tooth). An
+extinct genus of Elephantine Mammals.<br/>
+MEGALONYX (Gr. <i>megas</i>, great; <i>onux</i>, nail). An extinct
+genus of Edentate Mammals.<br/>
+MEGALOSAURUS (Gr. <i>megas</i>, great; <i>saura</i>, lizard).
+A genus of Deinosaurian Reptiles.<br/>
+MEGATHERIUM (Gr. <i>megas</i>, great; <i>therion</i>, beast).
+An extinct genus of Edentata.<br/>
+MESOZOIC (Gr. <i>mesos</i>, middle; and <i>zoe</i>, life). The
+Secondary period in Geology.<br/>
+MICROLESTES (Gr. <i>mikros</i>, little; <i>lestes</i>, thief).
+An extinct genus of Triassic Mammals.<br/>
+MILLEPORA (Lat. <i>mille</i>, one thousand; <i>porus</i>, a pore).
+A genus of "Tabulate Corals."<br/>
+MIOCENE (Gr. <i>meion</i>, less; <i>kainol</i>, new). The Middle
+Tertiary period.<br/>
+MOLARS (Lat. <i>mola</i>, a mill). The "grinders" in man, or the
+teeth in diphyodont Mammals which are not preceded by
+milk-teeth.<br/>
+MOLLUSCA (Lat. <i>mollis</i>, soft). The sub-kingdom which includes
+the Shell-fish proper, the <i>Polyzoa</i>, the <i>Tunicata</i>,
+and the Lamp-shells; so called from the generally soft nature
+of their bodies.<br/>
+MOLLUSCOIDA (<i>Mollusca</i>; Gr. <i>eidos</i>, form). The lower
+division of the <i>Mollusca</i>, comprising the <i>Polyzoa,
+Tunicata</i>, and <i>Brachiopoda</i>.<br/>
+MONOGRAPTUS (Gr. <i>monos</i>, single; <i>grapho</i>, I write).
+A genus of Graptolites.<br/>
+MYLODON (Gr. <i>mulos</i>, a mill; <i>odous</i>, tooth). An extinct
+genus of Edentate Mammals.<br/>
+MYRIAPODA or MYRIOPODA (Gr. <i>murios</i>, ten thousand;
+<i>podes</i>, feet). A class of <i>Arthropoda</i> comprising
+the Centipedes and their allies, characterised by their numerous
+feet.
+</p>
+
+<p>
+<a name="page_389"><span class="page">Page 389</span></a>
+NATATORES (Lat. <i>nare</i>, to swim). The order of the Swimming
+Birds.<br/>
+NATATORY (Lat. <i>nare</i>, to swim). Formed for swimming.<br/>
+NAUTILOID. Resembling the shell of the <i>Nautilus</i> in
+shape.<br/>
+NERVURES (Lat. <i>nervus</i>, a sinew). The ribs which support
+the membranous wings of insects.<br/>
+NEUROPTERA (Gr. <i>neuron</i>, a nerve; <i>pteron</i>, a wing).
+An order of Insects characterised by four membranous wings with
+numerous reticulated nervures (<i>e.g.</i>, Dragon-flies).<br/>
+NEUROPTERIS (Gr. <i>neuron</i>, a nerve; <i>pteris</i>, a fern).
+An extinct genus of Ferns.<br/>
+NOTHOSAURUS (Gr. <i>nothos</i>, spurious; <i>saura</i>, lizard).
+A genus of <i>Plesiosaurian</i> Reptiles.<br/>
+NOTOCHORD (Gr. <i>notos</i>, back; <i>chorde</i>, string). A
+cellular rod which is developed in the embryo of Vertebrates
+immediately beneath the spinal cord, and which is usually replaced
+in the adult by the vertebral column. Often it is spoken of as
+the "chorda dorsalis."<br/>
+NUDIBRANCHIATA (Lat. <i>nudus</i>, naked; and Gr. <i>bragchia</i>,
+gill). An order of the <i>Gasteropoda</i> in which the gills
+are naked.<br/>
+NUMMULINA (Lat. <i>nummus</i>, a coin). A genus of
+<i>Foraminifera</i>, comprising the coin-shaped "Nummulites."
+</p>
+
+<p>
+OBOLELLA (Lat. dim. of <i>obolus</i>, a small coin). An extinct
+genus of Brachiopods.<br/>
+OCCIPITAL. Connected with the <i>occiput</i>, or the back part
+of the head.<br/>
+OCEANIC. Applied to animals which inhabit the open ocean (=
+pelagic).<br/>
+ODONTOPTERYX (Gr. <i>oduos</i>, tooth; <i>pterux</i>, wing). An
+extinct genus of Birds.<br/>
+ODONTORNITHES (Gr. <i>oduos</i>, tooth; <i>ornis</i>, bird).
+The extinct order of Birds, comprising forms with distinct teeth
+in sockets.<br/>
+OLIGOCENE (Gr. <i>oligos</i>, few; <i>kainos</i>, new). A name
+used by many Continental geologists as synonymous with the Lower
+Miocene.<br/>
+OPHIDIA (Gr. <i>ophis</i>, a serpent). The order of Reptiles
+comprising the Snakes.<br/>
+OPHIUROIDEA (Gr. <i>ophis</i>, snake; <i>oura</i>, tail;
+<i>eidos</i>, form). An order of <i>Echinodermata</i>, comprising
+the Brittle-stars and Sand-stars.<br/>
+ORNITHOSCELIDA (Gr. <i>ornis</i>, bird; <i>skelos</i>, leg).
+Applied by Huxley to the Deinosaurian Reptiles, together with the
+genus <i>Compsognathus</i>, on account of the bird-like character
+of their hind-limbs.<br/>
+ORTHIS (Gr. <i>orthos</i>, straight). A genus of Brachiopods,
+named in allusion to the straight hinge-line.<br/>
+ORTHOCERATIDÆ (Gr. <i>orthos</i>, straight; <i>keras</i>,
+horn). A family of the <i>Nautilidœ</i>, in which the shell
+is straight, or nearly so.<br/>
+ORTHOPTERA (Gr. <i>orthos</i>, straight; <i>pteron</i>, wing).
+An order of Insects.<br/>
+OSTEOLEPIS (Gr. <i>osteon</i>, bone; <i>lepis</i>, scale). An
+extinct genus of Ganoid Fishes.<br/>
+OSTRACODA (Gr. <i>ostrakon</i>, a shell). An order of small
+Crustaceans which are enclosed in bivalve shells.<br/>
+OTODUS (Gr. <i>ota</i>, ears; <i>odous</i>, tooth). An extinct
+genus of Sharks.<br/>
+OUDENODON (Gr. <i>ouden</i>, none; <i>odous</i>, tooth). A genus
+of Dicynodont Reptiles.<br/>
+OVIBUS (Lat. <i>ovis</i>, sheep; <i>bos</i>, ox). The genus
+comprising the Musk-ox.
+</p>
+
+<p>
+PACHYDERMATA (Gr. <i>pachus</i>, thick; <i>derma</i>, skin).
+An old Mammalian order constituted by Cuvier for the reception
+of the Rhinoceros, Hippopotamus, Elephant, &amp;c.<br/>
+PALÆASTER (Gr. <i>palaios</i>, ancient; <i>aster</i>, star).
+An extinct genus of Star-fishes.<br/>
+PALÆOCARIS (Gr. <i>palaios</i>, ancient; <i>karis</i>, shrimp).
+An extinct genus of Decapod Crustaceans.<br/>
+PALÆOLITHIC (Gr. <i>palaios</i>, ancient; <i>lithos</i>,
+stone). Applied to the rude stone implements of the earliest known
+races of men, to the men who made these implements, or to the
+period at which they were made.<br/>
+<a name="page_390"><span class="page">Page 390</span></a>
+PALÆONTOLOGY (Gr. <i>palaios</i>, ancient; and <i>logos</i>,
+discourse). The science of fossil remains or of extinct organised
+beings.<br/>
+PALÆOPHIS (Gr. <i>palaios</i>, ancient; <i>ophis</i>, serpent).
+An extinct genus of Snakes.<br/>
+PALÆOSAURUS (Gr. <i>palaios</i>, ancient; <i>saura</i>, lizard).
+A genus of Thecodont Reptiles.<br/>
+PALÆOTHERIDÆ. (Gr. <i>palaios</i>, ancient; <i>ther</i>,
+beast). A group of Tertiary Ungulates.<br/>
+PALÆOZOIC (Gr. <i>palaios</i>, ancient; and <i>zoe</i>, life).
+Applied to the oldest of the great geological epochs.<br/>
+PARADOXIDES (Lat. <i>paradoxus</i>, marvellous). A genus of
+Trilobites.<br/>
+PATAGIUM (Lat. the border of a dress). Applied to the expansion
+of the integument by which Bats, Flying Squirrels, and other
+animals support themselves in the air.<br/>
+PECOPTERIS (Gr. <i>peko</i>, I comb; <i>pteris</i>, a fern). An
+extinct genus of Ferns.<br/>
+PECTEN (Lat. a comb). The genus of Bivalve Molluscs comprising
+the Scallops.<br/>
+PECTORAL (Lat. <i>pectus</i>, chest). Connected with, or placed
+upon, the chest.<br/>
+PENTACRINUS (Gr. <i>penta</i>, five; <i>krinon</i>, lily). A genus
+of Crinoids in which the column is five-sided.<br/>
+PENTAMERUS (Gr. <i>penta</i>, five; <i>meros</i>, part). An extinct
+genus of Brachiopods.<br/>
+PENTREMITES (Gr. <i>penta</i>, five; <i>trema</i>, aperture). A
+genus of <i>Blastoidea</i>, so named in allusion to the apertures
+at the summit of the calyx.<br/>
+PERENNIBRANCHIATA (Lat. <i>perennis</i>, perpetual; Gr.
+<i>bragchia</i>, gill). Applied to those Amphibia in which the
+gills are permanently retained throughout life.<br/>
+PERISSODACTYLA (Gr. <i>perissos</i>, uneven; <i>daktulos</i>,
+finger). Applied to those Hoofed Quadrupeds (<i>Ungulata</i>)
+in which the feet have an uneven number of toes.<br/>
+PETALOID. Shaped like the petal of a flower.<br/>
+PHACOPS (Gr. <i>phaké</i>, a lentil; <i>ops</i>, the eye).
+A genus of Trilobites.<br/>
+PHALANGES (Gr. <i>phalanx</i>, a row). The small bones composing
+the digits of the higher <i>Vertebrata</i>. Normally each digit
+has three phalanges.<br/>
+PHANEROGAMS (Gr. <i>phaneros</i>, visible; <i>gamos</i>, marriage).
+Plants which have the organs of reproduction conspicuous, and
+which bear true flowers.<br/>
+PHARYNGOBRANCHII (Gr. <i>pharugx</i>, pharynx; <i>bragchia</i>,
+gill). The order of Fishes comprising only the Lancelet.<br/>
+PHASCOLOTHERIUM (Gr. <i>phaskolos</i>, a pouch; <i>therion</i>,
+a beast). A genus of Oolitic Mammals.<br/>
+PHRAGMACONE (Gr. <i>phragma</i>, a partition; and <i>konos</i>,
+a cone). The chambered portion of the internal shell of a
+<i>Belemnite</i>.<br/>
+PHYLLOPODA (Gr. <i>phullon</i>, leaf; and <i>pous</i>, foot).
+An order of <i>Crustacea</i>.<br/>
+PINNATE (Lat. <i>pinna</i>, a feather). Feather-shaped; or possessing
+lateral processes.<br/>
+PINNIGRADA (Lat. <i>pinna</i>, a feather; <i>gradior</i>, I walk).
+The group of <i>Carnivora</i>, comprising the Seals and Walruses,
+adapted for an aquatic life. Often called <i>Pinnipedia</i>.<br/>
+PINNULÆ. (Lat. dim. of <i>pinna</i>). The lateral processes of
+the arms of <i>Crinoids</i>.<br/>
+PISCES (Lat. <i>piscis</i>, a fish). The class of Vertebrates
+comprising the Fishes.<br/>
+PLACOID (Gr. <i>plax</i>, a plate; <i>eidos</i>, form). Applied
+to the irregular bony plates, grains, or spines which are found
+in the skin of various fishes (<i>Elasmobranchii</i>).<br/>
+PLAGIOSTOMI (Gr. <i>plagios</i>, transverse; <i>stoma</i>, mouth).
+The Sharks and Rays, in which the mouth is transverse, and is
+placed on the under surface of the head.<br/>
+PLATYCERAS (Gr. <i>platus</i>, broad; <i>keras</i>, horn). A genus
+of Univalve Molluscs.<br/>
+PLATYCRINUS (Gr. <i>platus</i>, broad; <i>krinom</i>, lily). A
+genus of Crinoidea.<br/>
+PLATYRHINA (Gr. <i>platus</i>, broad; <i>rhines</i>, nostrils).
+A group of the <i>Quadrumana</i>.<br/>
+PLATYSOMUS (Gr. <i>platus</i>, wide; <i>soma</i>, body). A genus
+of Ganoid Fishes.<br/>
+PLEISTOCENE (Gr. <i>pleistos</i>, most; <i>kainos</i>, new). Often
+used as synonymous with "Post-Pliocene."<br/>
+<a name="page_391"><span class="page">Page 391</span></a>
+PLEUROTOMARIA (Gr. <i>pleura</i>, the side; <i>tomé</i>,
+notch). A genus of Univalve shells.<br/>
+PLIOCENE (Gr. <i>pleion</i>, more; <i>kainos</i>, new). The later
+Tertiary period.<br/>
+PLIOPITHECUS (Gr. <i>pleion</i>, more; <i>pithekos</i>, ape).
+An extinct genus of monkeys.<br/>
+PLIOSAURUS (Gr. <i>pleion</i>, more; <i>saura</i>, lizard). A
+genus of Plesiosaurian Reptiles.<br/>
+POLYCYSTINA (Gr. <i>polus</i>, many; and <i>kustis</i>, a cyst).
+An order of <i>Protozoa</i> with foraminated siliceous shells.<br/>
+POLYPARY. The hard chitinous covering secreted by many of the
+<i>Hydrozoa</i>.<br/>
+POLYPE (Gr. <i>polus</i>, many; <i>pous</i>, foot). Restricted
+to the single individual of a simple <i>Actinozoön</i>, such
+as a Sea-anemone, or to the separate zooids of a compound
+<i>Actinozoön</i>. Often applied indiscriminately to any of
+the <i>Cœlenterata</i>, or even to the Polyzoa.<br/>
+POLYPORA (Gr. <i>polus</i>, many; <i>poros</i>, a passage). A
+genus of Lace-corals (<i>Fenestellidœ</i>).<br/>
+POLYTHALAMOUS (Gr. <i>polus</i>; and <i>thalamos</i>, chamber).
+Having many chambers; applied to the shells of <i>Foraminifera</i>
+and <i>Cephalopoda</i>.<br/>
+POLYZOA (Gr. <i>polus</i>; and <i>zoön</i>, animal). A division
+of the <i>Molluscoida</i> comprising compound animals, such as
+the Sea-mat&mdash;sometimes called <i>Bryozoa</i>.<br/>
+PORIFERA (Lat. <i>porus</i>, pore; and <i>fero</i>, I carry).
+Sometimes used to designate the <i>Foraminifera</i>, or the
+<i>Sponges</i>.<br/>
+PRÆMOLARS (Lat. <i>prœ</i>, before; <i>molares</i>, the
+grinders). The molar teeth of Mammals which succeed the molars of the
+milk-set of teeth. In man, the bicuspid teeth.<br/>
+PROBOSCIDEA (Lat. <i>proboscis</i>, the snout). The order of Mammals
+comprising the Elephants.<br/>
+PROCŒLOUS (Gr. <i>pro</i>, before; <i>koilos</i>, hollow).
+Applied to vertebræ the bodies of which are hollow or concave
+in front.<br/>
+PRODUCTA (Lat. <i>productus</i>, drawn out or extended). An extinct
+genus of Brachiopods, in which the shell is "eared," or has its
+lateral angles drawn out.<br/>
+PROTICHNITES (Gr. <i>protos</i>, first; <i>ichnos</i>, footprint).
+Applied to certain impressions in the Potsdam sandstone of North
+America, believed to have been produced by large Crustaceans.<br/>
+PROTOPHYTA (Gr. <i>protos</i>; and <i>phuton</i>, plant). The
+lowest division of plants.<br/>
+PROTOPLASM (Gr. <i>protos</i>; and <i>plasso</i> I mould). The
+elementary basis of organised tissues. Sometimes used synonymously
+for the "sarcode" of the <i>Protozoa</i>.<br/>
+PROTOROSAURUS or PROTEROSAURUS (Gr. <i>protos</i>, first;
+<i>orao</i>, I see or discover; <i>saura</i>, lizard: or
+<i>proteros</i>, earlier; <i>saura</i>, lizard). A genus of Permian
+lizards.<br/>
+PROTOZOA (Gr. <i>protos</i>; and <i>zoön</i>, animal). The
+lowest division of the animal kingdom.<br/>
+PSAMMODUS (Gr. <i>psammos</i>, sand; <i>odous</i>, tooth). An
+extinct genus of Cestraciont Sharks.<br/>
+PSEUDOPODIA (Gr. <i>pseudos</i>, falsity; and <i>pous</i>, foot).
+The extensions of the body-substance which are put forth by the
+<i>Rhizopoda</i> at will, and which serve for locomotion and
+prehension.<br/>
+PSILOPHYTON (Gr. <i>psilos</i>, bare; <i>phuton</i>, plant). An
+extinct genus of Lycopodiaceous plants.<br/>
+PTERANODON (Gr. <i>pteron</i>, wing; <i>a</i>, without; <i>odous</i>,
+tooth). A genus of Pterosaurian Reptiles.<br/>
+PTERASPIS (Gr. <i>pteron</i>, wing; <i>aspis</i>, shield). A genus
+of Ganoid Fishes.<br/>
+PTERICHTHYS (Gr. <i>pteron</i>, wing; <i>ichthus</i>, fish). A
+genus of Ganoid Fishes.<br/>
+PTERODACTYLUS (Gr. <i>pteron</i>, wing; <i>daktulos</i>, finger).
+A genus of Pterosaurian Reptiles.<br/>
+PTEROPODA (Gr. <i>pteron</i>, wing; and <i>pous</i>, foot). A
+class of the <i>Mollusca</i> which swim by means of fins attached
+near the head.<br/>
+PTEROSAURIA (Gr. <i>pteron</i>, wing; <i>saura</i>, lizard). An
+extinct order of Reptiles.<br/>
+PTILODICTYA (Gr. <i>ptilon</i>, a feather; <i>diktuon</i>, a net).
+An extinct genus of <i>Polyzoa</i>.<br/>
+<a name="page_392"><span class="page">Page 392</span></a>
+PTYCHOCERAS (Gr. <i>ptucé</i>, a fold; <i>keras</i>, a
+horn). A genus of <i>Ammonitidœ</i>.<br/>
+PULMONATE. Possessing lungs.<br/>
+PYRIFORM (Lat. <i>pyrus</i>, a pear; and <i>forma</i>, form).
+Pear-shaped.
+</p>
+
+<p>
+QUADRUMANA (Lat. <i>quatuor</i>, four; <i>manus</i>, hand). The
+order of Mammals comprising the Apes, Monkeys, Baboons, Lemurs,
+&amp;c.
+</p>
+
+<p>
+RADIATA (Lat. <i>radius</i>, a ray). Formerly applied to a large
+number of animals which are now placed in separate sub-kingdoms
+(e.g., the <i>Cœlenterata</i>, the <i>Echinodermata</i>, the
+<i>Infusoria</i>, &amp;c.)<br/>
+RADIOLARIA (Lat. <i>radius</i>, a ray). A division of
+<i>Protozoa</i>.<br/>
+RAMUS (Lat. a branch). Applied to each half or branch of the lower
+jaw, or mandible, of Vertebrates.<br/>
+RAPTORES (Lat. <i>rapto</i>, I plunder). The order of the Birds
+of Prey.<br/>
+RASORES (Lat. <i>rado</i>, I scratch). The order of the Scratching
+Birds (Fowls. Pigeons, &amp;c.)<br/>
+RECEPTACULITES (Lat. <i>receptaculum</i>, a storehouse). An extinct
+genus of Protozoa.<br/>
+REPTILIA (Lat. <i>repto</i>, I crawl). The class of the
+<i>Vertebrata</i> comprising the Tortoises, Snakes, Lizards,
+Crocodiles, &amp;c.<br/>
+RETEPORA (Lat. <i>reté</i>, a net; <i>porus</i>, a pore). A
+genus of Lace-corals (<i>Polyzoa</i>).<br/>
+RHAMPHORHYNCHUS (Gr. <i>rhamphos</i>, beak; <i>rhugchos</i>, nose).
+A genus of Pterosaurian Reptiles.<br/>
+RHINOCEROS (Gr. <i>rhis</i>, the nose; <i>keras</i>, horn). A
+genus of Hoofed Quadrupeds.<br/>
+RHIZOPODA (Gr. <i>rhiza</i>, a root; and <i>pous</i>, foot).
+The division of <i>Protozoa</i> comprising all those which are
+capable of emitting pseudopodia.<br/>
+RHYNCHOLITES (Gr. <i>rhugchos</i>, beak; and <i>lithos</i>, stone).
+Beak-shaped fossils consisting of the mandibles of
+<i>Cephalopoda</i>.<br/>
+RHYNCHONELLA (Gr. <i>rhugchos</i>, nose or beak). A genus of
+Brachiopods.<br/>
+RODENTIA (Lat. <i>rodo</i>, I gnaw). An order of the Mammals;
+often called <i>Glires</i> (Lat. <i>glis</i>, a dormouse).<br/>
+ROTALIA (Lat. <i>rota</i>, a wheel). A genus of
+<i>Foraminifera</i>.<br/>
+RUGOSA (Lat. <i>rugosus</i>, wrinkled). An order of Corals.<br/>
+RUMINANTIA (Lat. <i>ruminor</i>, I chew the cud). The group of
+Hoofed Quadrupeds (<i>Ungulata</i>) which "ruminate" or chew
+the cud.<br/>
+</p>
+
+<p>
+SARCODE (Gr. <i>sarx</i>, flesh; <i>eidos</i>, form). The jelly-like
+substance of which the bodies of the <i>Protozoa</i> are composed.
+It is an albuminous body containing oil-granules, and is sometimes
+called "animal protoplasm."<br/>
+SAURIA (Gr. <i>saura</i>, a lizard). Any lizard-like Reptile is
+often spoken of as a "Saurian;" but the term is sometimes restricted
+to the Crocodiles alone, or to the Crocodiles and Lacertilians.<br/>
+SAUROPTERYGIA (Gr. <i>sauro</i>; <i>pterux</i>, wing). An extinct
+order of Reptiles, called by Huxley <i>Plesiosauria</i>, from
+the typical genus <i>Plesiosaurus</i>.<br/>
+SAURURÆ (Gr. <i>saura</i>; <i>oura</i>, tail). The extinct order
+of Birds comprising only the <i>Archœopteryx</i>.<br/>
+SCANSORES (Lat. <i>scando</i>, I climb). The order of the Climbing
+Birds (Parrots, Woodpeckers, &amp;c.)<br/>
+SCAPHITES (Lat. <i>scapha</i>, a boat). A genus of the
+<i>Ammonitidœ</i>.<br/>
+SCOLITHUS (Gr. <i>skolex</i>, a worm; <i>lithos</i>, a stone).
+The vertical burrows of sea-worms in rocks.<br/>
+SCUTA (Lat. <i>scutum</i>, a shield). Applied to any shield-like
+plates; especially to those which are developed in the integument
+of many Reptiles.<br/>
+SELACHIA or SELACHII (Gr. <i>selachos</i>, a cartilaginous fish,
+probably a shark). The sub-order of <i>Elasmobranchii</i> comprising
+the Sharks and Dog-fishes.<br/>
+SEPIOSTAIRE. The internal shell of the Sepia, commonly known as
+the "cuttle-bone."<br/>
+SEPTA. Partitions.<br/>
+SERPENTIFORM. Resembling a serpent in shape.<br/>
+SERTULARIDA (Lat. <i>sertum</i>, a wreath). An order of
+<i>Hydrozoa</i>.<br/>
+<a name="page_393"><span class="page">Page 393</span></a>
+SESSILE (Lat. <i>sedo</i>, I sit). Not supported upon a stalk or
+peduncle; attached by a base.<br/>
+SETHÆ (Lat. bristles). Bristles or long stiff hairs.<br/>
+SIGILLARIOIDS (Lat. <i>sigilla</i>, little images). A group of
+extinct plants of which <i>Sigillaria</i> is the type, so called
+from the seal-like markings on the bark.<br/>
+SILICEOUS (Lat. <i>silex</i>, flint). Composed of flint.<br/>
+SINISTRAL (Lat. <i>sinistra</i>, the left hand). Left-handed;
+applied to the direction of the spiral in certain shells, which
+are said to be "reversed."<br/>
+SIPHON (Gr. a tube). Applied to the respiratory tubes in the
+<i>Mollusca</i>; also to other tubes of different functions.<br/>
+SIPHONIA (Gr. <i>siphon</i>, a tube). A genus of fossil Sponges.<br/>
+SIPHONOSTOMATA (Gr. <i>siphon</i>; and <i>stoma</i>, mouth). The
+division of <i>Gasteropodous Molluscs</i> in which the aperture
+of the shell is not "entire," but possesses a notch or tube for
+the emission of the respiratory siphon.<br/>
+SIPHUNCLE (Lat. <i>siphunculus</i>, a little tube). The tube
+which connects together the various chambers of the shell of
+certain <i>Cephalopoda</i> (<i>e.g.</i>, the Pearly Nautilus).<br/>
+SIRENIA (Gr. <i>seiren</i>. a mermaid). The order of <i>Mammalia</i>
+comprising the Dugongs and Manatees.<br/>
+SIVATHERIUM (<i>Siva</i>, a Hindoo deity; Gr. <i>therion</i>,
+beast). An extinct genus of Hoofed Quadrupeds.<br/>
+SOLIDUNGULA (Lat. <i>solidus</i>, solid; <i>ungula</i>, a hoof).
+The group of Hoofed Quadrupeds comprising the Horse, Ass, and
+Zebra, in which each foot has only a single solid hoof. Often
+called <i>Solipedia</i>.<br/>
+SPHENOPTERIS (Gr. <i>sphen</i>, a wedge; <i>pteris</i>, a fern).
+An extinct genus of ferns.<br/>
+SPICULA (Lat. <i>spicidum</i>, a point). Pointed needle-shaped
+bodies.<br/>
+SPIRIFERA (Lat. <i>spira</i>, a spire or coil; <i>fero</i>, I
+carry). An extinct genus of Brachiopods, with large spiral supports
+for the "arms."<br/>
+SPIRORBIS (Lat. <i>spira</i>, a spire; <i>orbis</i>, a circle).
+A genus of tube-inhabiting Annelides, in which the shelly tube
+is coiled into a spiral disc.<br/>
+SPONGIDA (Gr. <i>spoggos</i>, a sponge). The division of
+<i>Protozoa</i> commonly known as sponges.<br/>
+STALACTITES (Gr. <i>stalasso</i>, I drop). Icicle-like encrustations
+and deposits of lime, which hang from the roof of caverns in
+limestone.<br/>
+STALAGMITE (Gr. <i>stalagma</i>, a drop). Encrustations of lime
+formed on the floor of caverns which are hollowed out of
+limestone.<br/>
+STIGMARIA (Gr. <i>stigma</i>, a mark made with a pointed instrument).
+A genus founded on the roots of various species of
+<i>Sigillaria</i>.<br/>
+STRATUM (Lat. <i>stratus</i>, spread out; or <i>stratum</i>, a
+thing spread out). A layer of rock.<br/>
+STROMATOPORA (Gr. <i>stroma</i>, a thing spread out; <i>paras</i>,
+a passage or pore). A Palæozoic genus of <i>Protozoa</i>.<br/>
+STROPHOHENA (Gr. <i>strophao</i>, I twist; <i>mené</i>, moon).
+An extinct genus of Brachiopods.<br/>
+SUB-CALCAREOUS. Somewhat calcareous.<br/>
+SUB-CENTRAL. Nearly central, but not quite.<br/>
+SUTURE (Lat. <i>suo</i>, I sew). The line of junction of two
+parts which are immovably connected together. Applied to the
+line where the whorls of a univalve shell join one another; also
+to the lines made upon the exterior of the shell of a chambered
+<i>Cephalopod</i> by the margins of the septa.<br/>
+SYRINGOPORA (Gr. <i>surigx</i>, a pipe; <i>poros</i>, a pore).
+A genus of Tabulate Corals.
+</p>
+
+<p>
+TABULÆ. (Lat. <i>tabula</i>, a tablet). Horizontal plates or
+floors found in some Corals, extending across the cavity of the
+"theca" from side to side.<br/>
+TEGUMENTARY (Lat. <i>tegumentum</i>, a covering). Connected with
+the integument or skin.<br/>
+TELEOSAURUS (Gr. <i>teleios</i>, perfect; <i>saura</i>, lizard).
+An extinct genus of Crocodilian Reptiles.<br/>
+TELEOSTEI (Gr. <i>teleios</i>, perfect; <i>osteon</i>, bone).
+The order of the "Bony Fishes."<br/>
+<a name="page_394"><span class="page">Page 394</span></a>
+TELSON (Gr. a limit). The last joint in the abdomen of
+<i>Crustacea</i>; variously regarded as a segment without
+appendages, or as an azygous appendage.<br/>
+TENTACULITES (Lat. <i>tentaculum</i>, a feeler). A genus of
+<i>Pteropoda</i>.<br/>
+TEREBRATULA (Lat. <i>terebratus</i>, bored or pierced). A genus
+of <i>Brachiopoda</i>, so called in allusion to the perforated
+beak of the ventral valve.<br/>
+TEST (Lat. <i>testa</i>, shell). The shell of <i>Mollusca</i>,
+which are for this reason sometimes called "<i>Testacea</i>;"
+also, the calcareous case of <i>Echinoderms</i>; also, the thick
+leathery outer tunic in the <i>Tunicata</i>.<br/>
+TESTACEOUS. Provided with a shell or hard covering.<br/>
+TESTUDINIDÆ (Lat. <i>testudo</i>, a tortoise). The family of
+the Tortoises.<br/>
+TETRABRANCHIATA (Gr. <i>tetra</i>, four; <i>bragchia</i>, gill).
+The order of <i>Cephalopoda</i> characterised by the possession
+of four gills.<br/>
+TEXTULARIA. (Lat. <i>textilis</i>, woven). A genus of
+<i>Foraminifera</i>.<br/>
+THECA (Gr. <i>theké</i>, a sheath). A genus of Pteropods.<br/>
+THECODONTOSAURUS (Gr. <i>theké</i>, a sheath; <i>odous</i>,
+tooth; <i>saura</i>, lizard). A genus of "Thecodont" Reptiles, so
+named in allusion to the fact that the teeth are sunk in distinct
+sockets.<br/>
+THERIODONT (Gr. <i>therion</i>, a beast; <i>odous</i>, tooth). A
+group of Reptiles so named by Owen in allusion to the Mammalian
+character of their teeth.<br/>
+THORAX (Gr. a breastplate). The region of the chest.<br/>
+THYLACOLEO (Gr. <i>thulakos</i>, a pouch; <i>leo</i>, a lion).
+An extinct genus of Marsupials.<br/>
+TRIGONIA (Gr. <i>treis</i>, three; <i>gonia</i>, angle). A genus
+of Bivalve Molluscs.<br/>
+TRIGONOCARPON (Gr. <i>treis</i>, three; <i>gonia</i>. angle;
+<i>karpos</i>, fruit). A genus founded on fossil fruits of a
+three-angled form.<br/>
+TRILOBITA (Gr. <i>treis</i>, three; <i>lobos</i>, a lobe). An
+extinct order of <i>Crustaceans</i>.<br/>
+TRINUCLEUS (Lat. <i>tris</i>, three; <i>nucleus</i>, a kernel).
+A genus of Trilobites.<br/>
+TROGONTHERIUM (Gr. <i>trogo</i>, I gnaw; <i>therion</i>, beast).
+An extinct genus of Beavers.<br/>
+TUBICOLA (Lat. <i>tuba</i>, a tube; and <i>colo</i>, I inhabit).
+The order of <i>Annelida</i> which construct a tubular case in
+which they protect themselves.<br/>
+TUBICOLOUS. Inhabiting a tube.<br/>
+TUNICATA (Lat. <i>tunica</i>, a cloak). A class of <i>Molluscoida</i>
+which are enveloped in a tough leathery case or "test."<br/>
+TURBINATED (Lat. <i>turbo</i>, a top). Top-shaped; conical with
+a round base.<br/>
+TURRILITES (Lat, <i>turris</i>, a tower). A genus of the
+<i>Ammonitidœ</i>.<br/>
+</p>
+
+<p>
+UMBO (Lat. the boss of a shield). The beak of a bivalve shell.<br/>
+UNGUICULATE (Lat. <i>unguis</i>, nail). Furnished with claws.<br/>
+UNGULATA (Lat. <i>ungula</i>, hoof). The order of Mammals comprising
+the Hoofed Quadrupeds.<br/>
+UNGULATE. Furnished with expanded nails constituting hoofs.<br/>
+UNILOCULAR (Lat. <i>unus</i>, one; and <i>loculus</i>. a little
+purse). Possessing a single cavity or chamber. Applied to the
+shells of <i>Foraminifera</i> and <i>Mollusca</i>.<br/>
+UNIVALVE (Lat. <i>unus</i>, one; <i>valvœ</i>, folding-doors).
+A shell composed of a single piece or valve.<br/>
+URODELA (Gr. <i>oura</i>, tail; <i>delos</i>, visible). The order
+of the Tailed Amphibians (Newts, &amp;c.)
+</p>
+
+<p>
+VENTRAL (Lat. <i>venter</i>, the stomach). Relating to the inferior
+surface of the body.<br/>
+VENTRICULITES (Lat. <i>ventriculum</i>, a little stomach). A genus
+of siliceous Sponges.<br/>
+VERMIFORM (Lat. <i>vermis</i>, worm; and <i>forma</i>, form).
+Worm-like.<br/>
+VERTEBRA (Lat. <i>verto</i>, I turn). One of the bony segments
+of the vertebral column or backbone.<br/>
+VERTEBRATA (Lat. <i>vertebra</i>, a bone of the back, from
+<i>vertere</i>, to turn). The division of the Animal Kingdom
+roughly characterised by the possession of a backbone.<br/>
+VESICLE (Lat. <i>vesica</i>, a bladder). A little sac or cyst.
+</p>
+
+<p>
+<a name="page_395"><span class="page">Page 395</span></a>
+WHORL. The spiral turn of a univalve shell.
+</p>
+
+<p>
+XIPHOSURA (Gr. <i>xiphos</i>, a sworn; and <i>oura</i>, tail).
+An order of <i>Crustacea</i>, comprising the <i>Limuli</i> or
+King-Crabs, characterised by their long sword-like tails.<br/>
+XYLOBIUS (Gr. <i>xulon</i>, wood; <i>bios</i>, life). An extinct
+genus of Myriapods, named in allusion to the fact that the animal
+lived on decaying wood.
+</p>
+
+<p>
+ZAPHRENTIS (proper name). A genus of Rugose Corals.<br/>
+ZEUGLODONTIDÆ. (Gr. <i>zeuglé</i>, a yoke;
+<i>odous</i>, a tooth). An extinct family of Cetaceans, in which
+the molar teeth are two-fanged, and look as if composed of two
+parts united by a neck.<br/>
+ZOOPHYTE (Gr. <i>zoön</i>, animal; <i>phuton</i>, plant).
+Loosely applied to many plant-like animals, such as Sponges,
+Corals, Sea-anemones, Sea-mats, &amp;c.
+</p>
+
+<h3>
+<a name="page_396"><span class="page">Page 396</span></a>
+INDEX.</h3>
+
+<hr />
+
+<!-- The original index was arranged in two columns. -->
+
+<p class="index">
+Acadian Group, <a href="#page_79">79</a>.<br/>
+<i>Acer</i>, <a href="#page_308">308</a>.<br/>
+<i>Acervularia</i>, <a href="#page_119">119</a>,
+  <a href="#page_173">173</a>.<br/>
+<i>Acidaspis</i>, <a href="#page_123">123</a>.<br/>
+Acorn-shells, <a href="#page_267">267</a>.<br/>
+<i>Acroculia</i>, <a href="#page_128">128</a>.<br/>
+<i>Acrodus</i>, <a href="#page_214">214</a>,
+  <a href="#page_242">242</a>, <a href="#page_275">275</a>;
+  <i>nobilis</i>, <a href="#page_242">242</a>.<br/>
+<i>Acrotreta</i>, <a href="#page_110">110</a>.<br/>
+<i>Acroura</i>, <a href="#page_120">120</a>.<br/>
+<i>Actinocrinus</i>, <a href="#page_175">175</a>.<br/>
+<i>Æglina</i>, <a href="#page_108">108</a>.<br/>
+<i>Æpiornis</i>, <a href="#page_348">348</a>.<br/>
+<i>Agnostus</i>, <a href="#page_85">85-87</a>,
+  <a href="#page_108">108</a>; <i>rex</i>,
+  <a href="#page_85">85</a>.<br/>
+<i>Alces malchis</i>, <a href="#page_354">354</a>.<br/>
+<i>Alecto</i>, <a href="#page_108">108</a>.<br/>
+<i>Alethopteris</i>, <a href="#page_136">136</a>,
+  <a href="#page_165">165</a>, <a href="#page_196">196</a>.<br/>
+<i>Algœ</i> (<i>see</i> Sea-weeds).<br/>
+Alligators, <a href="#page_218">218</a>,
+  <a href="#page_297">297</a>.<br/>
+<i>Alnus</i>, <a href="#page_262">262</a>.<br/>
+<i>Amblypterus</i>, <a href="#page_188">188</a>;
+  <i>macropterus</i>, <a href="#page_188">188</a>.<br/>
+<i>Ambonychia</i>, <a href="#page_111">111</a>.<br/>
+<i>Ammonites</i>, <a href="#page_187">187</a>,
+  <a href="#page_212">212-214</a>, <a href="#page_237">237-239</a>,
+  <a href="#page_272">272</a>;
+  <i>Humpresianus</i>, <a href="#page_238">238</a>;
+  <i>bifrons</i>, <a href="#page_238">238</a>.<br/>
+<i>Ammonitidœ</i>, <a href="#page_239">239</a>,
+  <a href="#page_272">272</a>, <a href="#page_285">285</a>,
+  <a href="#page_294">294</a>.<br/>
+<i>Amphibia</i>, <a href="#page_189">189</a>; of the Carboniferous,
+  <a href="#page_189">189-191</a>; of the Permian,
+  <a href="#page_200">200</a>; of the Trias,
+  <a href="#page_215">215-217</a>;
+  of the Jurassic, <a href="#page_242">242</a>;
+  of the Miocene, <a href="#page_313">313</a>.<br/>
+<i>Amphicyon</i>, <a href="#page_322">322</a>.<br/>
+<i>Amphilestes</i>, <a href="#page_253">253</a>.<br/>
+<i>Amphispongia</i>, <a href="#page_118">118</a>.<br/>
+<i>Amphistegina</i>, <a href="#page_311">311</a>.<br/>
+<i>Amphitherium</i>, <a href="#page_253">253</a>,
+  <a href="#page_255">255</a>; <i>Prevostii</i>,
+  <a href="#page_254">254</a>.<br/>
+<i>Amphitragulus</i>, <a href="#page_317">317</a>.<br/>
+<i>Amplexus</i>, <a href="#page_173">173</a>;
+  <i>coralloides</i>, <a href="#page_174">174</a>.<br/>
+<i>Ampyx</i>, <a href="#page_108">108</a>.<br/>
+<i>Anachytes</i>, <a href="#page_266">266</a>.<br/>
+<i>Anchitherium</i>, <a href="#page_301">301-302</a>.<br/>
+<i>Ancyloceras</i>, <a href="#page_272">272</a>,
+  <a href="#page_273">273</a>; <i>Matheronianus</i>,
+  <a href="#page_273">273</a>.<br/>
+<i>Ancylotherium Pentelici</i>, <a href="#page_315">315</a>.<br/>
+<i>Andrias Scheuchzeri</i>, <a href="#page_313">313</a>,
+  <a href="#page_314">314</a>.<br/>
+<i>Angiosperms</i>, <a href="#page_261">261</a>,
+  <a href="#page_262">262</a>.<br/>
+Animal Kingdom, divisions of, <a href="#page_375">375-378</a>.<br/>
+<i>Anisopus</i>, <a href="#page_206">206</a>.<br/>
+<i>Annelida</i>, of the Cambrian period, <a href="#page_82">82</a>,
+  <a href="#page_83">83</a>; of the Lower Silurian,
+  <a href="#page_107">107</a>; of the Upper Silurian,
+  <a href="#page_122">122</a>, <a href="#page_123">123</a>;
+  of the Devonian, <a href="#page_143">143</a>,
+  <a href="#page_144">144</a>; of the Carboniferous,
+  <a href="#page_178">178</a>.<br/>
+<i>Annularia</i>, <a href="#page_137">137</a>,
+  <a href="#page_196">196</a>, <a href="#page_207">207</a>.<br/>
+<i>Anomodontia</i>, <a href="#page_220">220</a>.<br/>
+<i>Anoplotheridœ</i>, <a href="#page_302">302</a>.<br/>
+<i>Anoplotherium</i>, <a href="#page_302">302</a>,
+  <a href="#page_303">303</a>; <i>commune</i>,
+  <a href="#page_303">303</a>.<br/>
+Ant-eaters, <a href="#page_299">299</a>,
+  <a href="#page_315">315</a>, <a href="#page_349">349</a>,
+  <a href="#page_350">350</a>, <a href="#page_353">353</a>.<br/>
+Antelopes, <a href="#page_317">317</a>.<br/>
+<i>Anthracosaurus Russelli</i>, <a href="#page_190">190</a>.<br/>
+<i>Anthrapalœmon gracilis</i>,
+  <a href="#page_180">180</a>.<br/>
+<i>Antilocapra</i>, <a href="#page_318">318</a>.<br/>
+<i>Antilope quadricornis</i>, <a href="#page_318">318</a>.<br/>
+Antwerp Crag, <a href="#page_325">325</a>.<br/>
+Apes, <a href="#page_323">323</a>.<br/>
+<i>Apiocrinus</i>, <a href="#page_231">231</a>.<br/>
+<i>Apteryx</i>, <a href="#page_346">346</a>,
+  <a href="#page_348">348</a>.<br/>
+Aqueous rocks, <a href="#page_15">15</a>.<br/>
+<i>Arachnida</i> of the Coal-measures,
+  <a href="#page_181">181</a>.<br/>
+Aralo-Caspian Beds, <a href="#page_326">326</a>.<br/>
+<i>Araucaria</i>, <a href="#page_262">262</a>.<br/>
+<i>Araucarioxylon</i>, <a href="#page_170">170</a>.<br/>
+<i>Arca</i>, <a href="#page_198">198</a>;
+  <i>antiqua</i>, <a href="#page_199">199</a>.<br/>
+<i>Archœocidaris</i>, <a href="#page_178">178</a>.<br/>
+<i>Archœocyathus</i>, <a href="#page_82">82</a>.<br/>
+<i>Archœopteryx</i>, <a href="#page_252">252</a>,
+  <a href="#page_281">281</a>; <i>macrura</i>,
+  <a href="#page_252">252</a>, <a href="#page_253">253</a>.<br/>
+<i>Archœospœrinœ</i>,
+  <a href="#page_75">75</a>.<br/>
+<i>Archimedes</i>, <a href="#page_184">184</a>;
+  <i>Wortheni</i>, <a href="#page_183">183</a>.<br/>
+<i>Archiulus</i>, <a href="#page_182">182</a>.<br/>
+Arctic regions, Miocene flora of,
+  <a href="#page_310">310</a>.<br/>
+<i>Arctocyon</i>, <a href="#page_304">304</a>.<br/>
+Arenaceous rocks, <a href="#page_20">20</a>.<br/>
+<i>Arenicolites</i>, <a href="#page_83">83</a>;
+  <i>didymus</i>, <a href="#page_88">88</a>.<br/>
+Arenig rocks, <a href="#page_92">92</a>,
+  <a href="#page_94">94</a>.<br/>
+Argillaceous rocks, <a href="#page_20">20</a>.<br/>
+Armadillos, <a href="#page_299">299</a>,
+  <a href="#page_351">351</a>, <a href="#page_353">353</a>.<br/>
+<i>Artiodactyle Ungulates</i>, <a href="#page_300">300</a>.<br/>
+<i>Asaphus</i>, <a href="#page_108">108</a>;
+  <i>tyrannus</i>, <a href="#page_107">107</a>,
+  <a href="#page_108">108</a>.<br/>
+<i>Ascoceras</i>, <a href="#page_130">130</a>.<br/>
+<i>Aspidella</i>, <a href="#page_76">76</a>.<br/>
+<i>Aspidura loricata</i>, <a href="#page_210">210</a>.<br/>
+<i>Astarte borealis</i>, <a href="#page_338">338</a>.<br/>
+<i>Asterophyllites</i>, <a href="#page_137">137</a>,
+  <a href="#page_196">196</a>.<br/>
+<i>Asterosteus</i>, <a href="#page_152">152</a>.<br/>
+<i>Astrœidœ</i>, <a href="#page_231">231</a>.<br/>
+<i>Astrœospongia</i>, <a href="#page_118">118</a>,
+  <a href="#page_139">139</a>.<br/>
+<i>Astylospongia</i>, <a href="#page_98">98</a>;
+  <i>prœmorsa</i>, <a href="#page_139">139</a>.<br/>
+<i>Athyris</i>, <a href="#page_110">110</a>,
+  <a href="#page_127">127</a>, <a href="#page_147">147</a>,
+  <a href="#page_198">198</a>; <i>subtilita</i>,
+  <a href="#page_185">185</a>.<br/>
+Atlantic Ooze, <a href="#page_22">22</a>,
+  <a href="#page_23">23</a>.<br/>
+<i>Atrypa</i>, <a href="#page_127">127</a>; <i>congesta</i>,
+  <a href="#page_127">127</a>; <i>hemispœrica</i>,
+  <a href="#page_127">127</a>; <i>reticularis</i>,
+  <a href="#page_147">147</a>, <a href="#page_148">148</a>.<br/>
+Auger-shells, <a href="#page_293">293</a>.<br/>
+Aurochs, <a href="#page_356">356</a>.<br/>
+Aves (<i>see</i> Birds).<br/>
+<a name="page_397"><span class="page">Page 397</span></a>
+<i>Avicula</i>, <a href="#page_235">235</a>; <i>cantorta</i>,
+  <a href="#page_211">211</a>, <a href="#page_212">212</a>;
+  <i>socialis</i>, <a href="#page_211">211</a>.<br/>
+"Avicula contorta Beds", <a href="#page_204">204</a>,
+  <a href="#page_212">212</a>.<br/>
+<i>Aviculidœ</i>, <a href="#page_198">198</a>,
+  <a href="#page_269">269</a>.<br/>
+<i>Aviculopecten</i>, <a href="#page_186">186</a>.<br/>
+<i>Axophyllum</i>, <a href="#page_173">173</a>.<br/>
+Aymestry Limestone, <a href="#page_116">116</a>,
+  <a href="#page_117">117</a>.<br/>
+Azoic rocks, <a href="#page_67">67</a>.
+</p>
+
+<p class="index">
+<i>Baculites</i>, <a href="#page_273">273</a>;
+  <i>anceps</i>, <a href="#page_274">274</a>.<br/>
+Bagshot and Bracklesham Beds, <a href="#page_287">287</a>.<br/>
+<i>Bakewellia</i>, <a href="#page_198">198</a>.<br/>
+<i>Balœna</i>, <a href="#page_315">315</a>.<br/>
+Bala Group, <a href="#page_93">93</a>,
+  <a href="#page_94">94</a>.<br/>
+Bala Limestone, <a href="#page_93">93</a>.<br/>
+<i>Balanidœ</i>, <a href="#page_267">267</a>.<br/>
+<i>Banksia</i>, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>.<br/>
+Barbadoes Earth, <a href="#page_33">33</a>.<br/>
+Barnacles, <a href="#page_267">267</a>.<br/>
+Bath Oolite, <a href="#page_227">227</a>.<br/>
+Bats, <a href="#page_304">304</a>, <a href="#page_322">322</a>.<br/>
+Bears, <a href="#page_330">330</a>, <a href="#page_359">359</a>.<br/>
+Beaver, <a href="#page_322">322</a>, <a href="#page_336">336</a>.<br/>
+Beetles, <a href="#page_182">182</a>, <a href="#page_311">311</a>.<br/>
+<i>Belemnitella mucronata</i>, <a href="#page_275">275</a>.<br/>
+<i>Beleminites</i>, <a href="#page_214">214</a>,
+  <a href="#page_240">240</a>, <a href="#page_274">274</a>;
+  <i>canaliculatus</i>, <a href="#page_241">241</a>.<br/>
+<i>Belemnitidœ</i>, <a href="#page_240">240</a>,
+  <a href="#page_285">285</a>.<br/>
+<i>Belemnoteuthis</i>, <a href="#page_240">240</a>.<br/>
+<i>Belinurus</i>, <a href="#page_179">179</a>.<br/>
+<i>Bellerophon</i>, <a href="#page_111">111</a>,
+  <a href="#page_129">129</a>, <a href="#page_148">148</a>,
+  <a href="#page_186">186</a>; <i>Argo</i>,
+  <a href="#page_111">111</a>.<br/>
+<i>Belodon</i>, <a href="#page_218">218</a>;
+  <i>Carolinensis</i>, <a href="#page_219">219</a>.<br/>
+<i>Belosepia</i>, <a href="#page_295">295</a>.<br/>
+<i>Beloteuthis subcostata</i>, <a href="#page_239">239</a>,
+  <a href="#page_240">240</a>.<br/>
+Bembridge Beds, <a href="#page_288">288</a>.<br/>
+<i>Beryx</i>, <a href="#page_276">276</a>;
+  <i>Lewesiensis</i>, <a href="#page_276">276</a>.<br/>
+<i>Beyrichia</i>, <a href="#page_107">107</a>;
+  <i>complicata</i>, <a href="#page_107">107</a>.<br/>
+Bird's-eye Limestone, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+Birds, of the Trias, <a href="#page_222">222</a>;
+  of the Jurassic, <a href="#page_251">251-253</a>;
+  of the Cretaceous, <a href="#page_281">281</a>,
+  <a href="#page_282">282</a>; of the Eocene,
+  <a href="#page_297">297</a>; of the Post-Pliocene,
+  <a href="#page_345">345-348</a>.<br/>
+<i>Bison priscus</i>, <a href="#page_356">356</a>.<br/>
+Bituminous Schists of Caithness, <a href="#page_36">36</a>.<br/>
+Bivalves (<i>see</i> Lamellibranchiata).<br/>
+Black-lead (<i>see</i> Graphite).<br/>
+Black-River Limestone, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+<i>Blastoidea</i>, <a href="#page_176">176</a>;
+  of the Devonian, <a href="#page_143">143</a>;
+  of the Carboniferous, <a href="#page_176">176</a>.<br/>
+<i>Boidœ</i>, <a href="#page_296">296</a>.<br/>
+Bolderberg Beds, <a href="#page_307">307</a>.<br/>
+Bone-bed, of the Upper Ludlow, <a href="#page_116">116</a>;
+  of the Trias, <a href="#page_224">224</a>.<br/>
+Bony Fishes (<i>see</i> Teleostean Fishes).<br/>
+<i>Bos primigenius</i>, <a href="#page_356">356</a>;
+  <i>taurus</i>, <a href="#page_356">356</a>.<br/>
+Boulder-clay, <a href="#page_337">337</a>.<br/>
+<i>Bourgueticrinus</i>, <a href="#page_266">266</a>.<br/>
+Bovey-Tracy Beds, <a href="#page_305">305</a>,
+  <a href="#page_309">309</a>.<br/>
+<i>Brachiopoda</i>, <a href="#page_125">125</a>;
+  of the Cambrian rocks, <a href="#page_87">87</a>;
+  of the Lower Silurian, <a href="#page_108">108-110</a>;
+  of the Upper Silurian, <a href="#page_125">125-128</a>;
+  of the Devonian, <a href="#page_147">147</a>,
+  <a href="#page_148">148</a>; of the Carboniferous,
+  <a href="#page_184">184-186</a>; of the Permian,
+  <a href="#page_198">198</a>; of the Trias,
+  <a href="#page_211">211</a>; of the Jurassic,
+  <a href="#page_234">234</a>; of the Cretaceous,
+  <a href="#page_268">268</a>; of the Eocene,
+  <a href="#page_292">292</a>.<br/>
+<i>Brachymetopus</i>, <a href="#page_179">179</a>.<br/>
+Brachyurous Crustaceans, <a href="#page_180">180</a>,
+  <a href="#page_197">197</a>.<br/>
+Bradford Clay, <a href="#page_227">227</a>.<br/>
+Breaks in the Geological and Palæontological record,
+  <a href="#page_44">44-52</a>.<br/>
+Breccia, <a href="#page_19">19</a>.<br/>
+Brick-earths, <a href="#page_339">339</a>.<br/>
+Bridlington Crag, <a href="#page_325">325</a>,
+  <a href="#page_326">326</a>, <a href="#page_336">336</a>.<br/>
+Brittle-stars (<i>see</i> Ophiuroidea).<br/>
+<i>Bronteus</i>, <a href="#page_145">145</a>.<br/>
+<i>Brontotheridœ</i>, <a href="#page_316">316</a>.<br/>
+<i>Brontotherium ingens</i>, <a href="#page_316">316</a>.<br/>
+<i>Brontozoum</i>, <a href="#page_206">206</a>.<br/>
+<i>Buccinum</i>, <a href="#page_237">237</a>.<br/>
+<i>Bucklandia</i>, <a href="#page_230">230</a>.<br/>
+<i>Bulimus</i>, <a href="#page_294">294</a>.<br/>
+Bunter Sandstein, <a href="#page_203">203</a>,
+  <a href="#page_204">204</a>, <a href="#page_206">206</a>.<br/>
+Butterflies, <a href="#page_233">233</a>,
+  <a href="#page_311">311</a>.<br/>
+<i>Byssoarca</i>, <a href="#page_198">198</a>.
+</p>
+
+<p class="index">
+Cainozoic (<i>see</i> Kainozoic).<br/>
+Calamaries, <a href="#page_239">239</a>.<br/>
+<i>Calamites</i>, <a href="#page_165">165</a>,
+  <a href="#page_166">166</a>, <a href="#page_196">196</a>;
+  <i>cannœformis</i>, <a href="#page_166">166</a>.<br/>
+Calcaire Grossier, <a href="#page_287">287</a>,
+  <a href="#page_288">288</a>.<br/>
+Calcareous rocks, <a href="#page_20">20-32</a>; Tufa,
+  <a href="#page_21">21</a>.<br/>
+Calciferous Sand-rock, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+<i>Calveria</i>, <a href="#page_178">178</a>.<br/>
+<i>Calymene</i>, <a href="#page_108">108</a>,
+  <a href="#page_123">123</a>; <i>Blumenbachii</i>,
+  <a href="#page_107">107</a>.<br/>
+<i>Camarophoria globulina</i>, <a href="#page_198">198</a>.<br/>
+Cambrian period, <a href="#page_77">77-90</a>;
+  rocks of, in Britain, <a href="#page_77">77</a>,
+  <a href="#page_78">78</a>; in Bohemia, <a href="#page_79">79</a>;
+  in North America, <a href="#page_79">79</a>; life of,
+  <a href="#page_80">80-90</a>.<br/>
+<i>Camelopardalidœ</i>, <a href="#page_317">317</a>.<br/>
+Camels, <a href="#page_317">317</a>, <a href="#page_354">354</a>.<br/>
+<i>Canis lupus</i>, <a href="#page_336">336</a>;
+  <i>Parisiensis</i>, <a href="#page_304">304</a>.<br/>
+Caradoc rocks, <a href="#page_93">93</a>,
+  <a href="#page_94">94</a>, <a href="#page_96">96</a>.<br/>
+Carbon, origin of, <a href="#page_36">36</a>.<br/>
+Carboniferous Limestone, <a href="#page_157">157</a>,
+  <a href="#page_158">158</a>.<br/>
+Carboniferous period, <a href="#page_157">157-192</a>;
+  rocks of, <a href="#page_157">157-160</a>; life of,
+  <a href="#page_160">160-191</a>.<br/>
+Carboniferous Slates of Ireland, <a href="#page_135">135</a>,
+  <a href="#page_158">158</a>, <a href="#page_159">159</a>.<br/>
+<i>Carcharias</i>, <a href="#page_275">275</a>.<br/>
+<i>Carcharodon</i>, <a href="#page_295">295</a>,
+  <a href="#page_312">312</a>; <i>productus</i>,
+  <a href="#page_313">313</a>.<br/>
+<i>Cardinia</i>, <a href="#page_235">235</a>.<br/>
+<i>Cardiocarpon</i>, <a href="#page_137">137</a>.<br/>
+<i>Cardiola</i>, <a href="#page_128">128</a>;
+  <i>fibrosa</i>, <a href="#page_128">128</a>;
+  <i>interrupta</i>, <a href="#page_128">128</a>.<br/>
+<i>Cardita</i>, <a href="#page_213">213</a>,
+  <a href="#page_292">292</a>; <i>planicosta</i>,
+  <a href="#page_292">292</a>, <a href="#page_293">293</a>.<br/>
+<i>Cardium</i>, <a href="#page_292">292</a>;
+  <i>Rhœticum</i>, <a href="#page_211">211</a>,
+  <a href="#page_212">212</a>.<br/>
+Caribou, <a href="#page_355">355</a>.<br/>
+<i>Carnivora</i>, of the Eocene, <a href="#page_304">304</a>;
+  of the Miocene, <a href="#page_322">322</a>; of the Pliocene,
+  <a href="#page_330">330</a>, <a href="#page_331">331</a>;
+  of the Post-Pliocene, <a href="#page_359">359-361</a>.<br/>
+<i>Caryocaris</i>, <a href="#page_107">107</a>,
+  <a href="#page_108">108</a>.<br/>
+<i>Caryocrinus ornatus</i>, <a href="#page_106">106</a>.<br/>
+<i>Castor fiber</i>, <a href="#page_336">336</a>.<br/>
+<i>Castoroides Ohioensis</i>, <a href="#page_361">361</a>.<br/>
+Catastrophism, theory of, <a href="#page_3">3</a>.<br/>
+<i>Catopterus</i>, <a href="#page_214">214</a>.<br/>
+Cauda-Galli Grit, <a href="#page_135">135</a>,
+  <a href="#page_137">137</a>.<br/>
+<i>Caulopteris</i>, <a href="#page_136">136</a>,
+  <a href="#page_164">164</a>.<br/>
+Cave-bear, <a href="#page_360">360</a>.<br/>
+Cave-deposits, <a href="#page_337">337</a>,
+  <a href="#page_339">339</a>, <a href="#page_341">341-344</a>.<br/>
+Cave-hyæna, <a href="#page_360">360</a>.<br/>
+Cave-lion, <a href="#page_361">361</a>.<br/>
+Caves, formation of, <a href="#page_341">341</a>; deposits in,
+  <a href="#page_342">342</a>.<br/>
+<i>Cavicornia</i>, <a href="#page_317">317</a>.<br/>
+Cement-stones, <a href="#page_31">31</a>.<br/>
+<i>Cephalaspis</i>, <a href="#page_152">152</a>.<br/>
+<i>Cephalopoda</i>, of the Cambrian period,
+  <a href="#page_88">88</a>; of the Lower Silurian,
+  <a href="#page_111">111-114</a>; of the Upper Silurian,
+  <a href="#page_130">130</a>; of the Devonian,
+  <a href="#page_149">149</a>; of the Carboniferous,
+  <a href="#page_186">186</a>, <a href="#page_187">187</a>;
+  of the Permian, <a href="#page_199">199</a>; of the Trias,
+  <a href="#page_212">212</a>; of the Jurassic,
+  <a href="#page_237">237-240</a>; of the Cretaceous,
+  <a href="#page_272">272-275</a>; of the Eocene,
+  <a href="#page_294">294</a>; of the Miocene,
+  <a href="#page_312">312</a>.<br/>
+<a name="page_398"><span class="page">Page 398</span></a>
+<i>Ceratiocaris</i>, <a href="#page_108">108</a>.<br/>
+<i>Ceratites</i>, <a href="#page_212">212-214</a>;
+  <i>nodosus</i>, <a href="#page_212">212</a>.<br/>
+<i>Ceratodus</i>, <a href="#page_214">214</a>;
+  <i>altus</i>, <a href="#page_214">214</a>;
+  <i>Fosteri</i>, <a href="#page_214">214</a>;
+  <i>serratus</i>, <a href="#page_214">214</a>.<br/>
+<i>Ceriopora</i>, <a href="#page_145">145</a>;
+  <i>Hamiltonensis</i>, <a href="#page_146">146</a>.<br/>
+<i>Cerithium</i>, <a href="#page_213">213</a>,
+  <a href="#page_293">293</a>; <i>hexagonum</i>,
+  <a href="#page_294">294</a>.<br/>
+<i>Cervidœ</i>, of the Miocene period,
+  <a href="#page_314">314</a>; of the Pliocene,
+  <a href="#page_329">329</a>; of the Post-Pliocene,
+  <a href="#page_354">354</a>, <a href="#page_355">355</a>.<br/>
+<i>Cervus</i>, <a href="#page_317">317</a>;
+  <i>capreolus</i>, <a href="#page_336">336</a>,
+  <a href="#page_354">354</a>; <i>elaphus</i>,
+  <a href="#page_336">336</a>, <a href="#page_355">355</a>;
+  <i>megaceros</i>, <a href="#page_354">354</a>,
+  <a href="#page_355">355</a>; <i>tarandus</i>,
+  <a href="#page_354">354</a>.<br/>
+<i>Cestracion Philippi</i>, <a href="#page_188">188</a>,
+  <a href="#page_255">255</a>.<br/>
+Cestracionts, of the Devonian, <a href="#page_154">154</a>;
+  of the Carboniferous, <a href="#page_188">188</a>;
+  of the Permian, <a href="#page_199">199</a>;
+  of the Trias, <a href="#page_214">214</a>;
+  of the Jurassic, <a href="#page_242">242</a>;
+  of the Cretaceous, <a href="#page_275">275</a>.<br/>
+<i>Cetacea</i>, <a href="#page_299">299</a>;
+  of the Eocene, <a href="#page_299">299</a>;
+  of the Miocene, <a href="#page_315">315</a>.<br/>
+<i>Cetiosaurus</i>, <a href="#page_249">249</a>,
+  <a href="#page_25">25</a>.<br/>
+<i>Chœropotamus</i>, <a href="#page_302">302</a>.<br/>
+<i>Chœtetes</i>, <a href="#page_105">105</a>,
+  <a href="#page_173">173</a>; <i>tumidus</i>,
+  <a href="#page_174">174</a>.<br/>
+Chain-coral, <a href="#page_119">119</a>.<br/>
+Chalk, <a href="#page_259">259</a>; structure of,
+  <a href="#page_21">21-23</a>; Foraminifera of,
+  <a href="#page_22">22</a>, <a href="#page_263">263</a>;
+  origin of, <a href="#page_23">23</a>; with flints,
+  <a href="#page_253">253</a>; without flints,
+  <a href="#page_259">259</a>.<br/>
+<i>Chama</i>, <a href="#page_236">236</a>.<br/>
+<i>Chamœrops</i>, <a href="#page_308">308</a>;
+  <i>Helvetica</i>, <a href="#page_309">309</a>.<br/>
+Chazy Limestone, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+<i>Cheiroptera</i>, of the Eocene, <a href="#page_304">304</a>,
+  <a href="#page_305">305</a>; of the Miocene,
+  <a href="#page_322">322</a>.<br/>
+<i>Cheirotherium</i>, <a href="#page_215">215</a>,
+  <a href="#page_216">216</a>.<br/>
+<i>Cheirurus</i>, <a href="#page_108">108</a>,
+  <a href="#page_123">123</a>; <i>bimucronatus</i>,
+  <a href="#page_124">124</a>.<br/>
+<i>Chelichnus Duncani</i>, <a href="#page_202">202</a>.<br/>
+<i>Chelone Benstedi</i>, <a href="#page_280">280</a>;
+  <i>planiceps</i>, <a href="#page_251">251</a>.<br/>
+<i>Chelonia</i>, of the Permian, <a href="#page_202">202</a>;
+  of the Jurassic, <a href="#page_251">251</a>;
+  of the Cretaceous, <a href="#page_280">280</a>;
+  of the Eocene, <a href="#page_296">296</a>;
+  of the Miocene, <a href="#page_213">213</a>.<br/>
+<i>Chemnitzia</i>, <a href="#page_213">213</a>.<br/>
+Chemung Group, <a href="#page_135">135</a>,
+  <a href="#page_136">136</a>, <a href="#page_137">137</a>.<br/>
+Chert, <a href="#page_34">34</a>.<br/>
+Chillesford Beds, <a href="#page_325">325</a>,
+  <a href="#page_326">326</a>, <a href="#page_336">336</a>.<br/>
+<i>Chonetes</i>, <a href="#page_127">127</a>,
+  <a href="#page_147">147</a>, <a href="#page_184">184</a>;
+  <i>Hardrensis</i>, <a href="#page_185">185</a>.<br/>
+<i>Chonophyllum</i>, <a href="#page_173">173</a>.<br/>
+<i>Cidaris</i>, <a href="#page_266">266</a>.<br/>
+Cincinnati Group, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+<i>Cinnamomum polymorphum</i>, <a href="#page_309">309</a>.<br/>
+Cinnamon-trees, <a href="#page_262">262</a>,
+  <a href="#page_290">290</a>, <a href="#page_306">306</a>,
+  <a href="#page_308">308</a>, <a href="#page_309">309</a>.<br/>
+<i>Cladodus</i>, <a href="#page_188">188</a>.<br/>
+Claiborne Beds, <a href="#page_289">289</a>.<br/>
+<i>Clathropora</i>, <a href="#page_145">145</a>;
+  <i>intertexta</i>, <a href="#page_146">146</a>.<br/>
+Clay, <a href="#page_20">20</a>; Red, origin of,
+  <a href="#page_35">35</a>.<br/>
+Clay-ironstone, nodules of, <a href="#page_31">31</a>.<br/>
+<i>Cleidophorus</i>, <a href="#page_111">111</a>.<br/>
+<i>Cleodora</i>, <a href="#page_312">312</a>.<br/>
+<i>Climacograptus</i>, <a href="#page_101">101</a>,
+  <a href="#page_119">119</a>.<br/>
+Clinton Formation, <a href="#page_116">116</a>,
+  <a href="#page_117">117</a>.<br/>
+<i>Clisiophyllum</i>, <a href="#page_173">173</a>.<br/>
+<i>Clupeidœ</i>, <a href="#page_276">276</a>.<br/>
+<i>Clymenia</i>, <a href="#page_149">149</a>;
+  <i>Sedgwickii</i>, <a href="#page_149">149</a>.<br/>
+Coal, <a href="#page_36">36</a>; structure of,
+  <a href="#page_163">163</a>; mode of formation of,
+  <a href="#page_162">162</a>.<br/>
+Coal-measures, <a href="#page_159">159</a>,
+  <a href="#page_160">160</a>; mineral characters of,
+  <a href="#page_159">159</a>; mode of formation of,
+  <a href="#page_160">160</a>, <a href="#page_162">162</a>;
+  plants of, <a href="#page_162">162-170</a>.<br/>
+Coccoliths, <a href="#page_261">261</a>.<br/>
+<i>Coccosteus</i>, <a href="#page_151">151</a>,
+  <a href="#page_152">152</a>.<br/>
+<i>Cochliodus</i>, <a href="#page_188">188</a>;
+  <i>cantortus</i>, <a href="#page_189">189</a>.<br/>
+<i>Coleoptera</i>, <a href="#page_182">182</a>,
+  <a href="#page_311">311</a>.<br/>
+<i>Colossochelys Atlas</i>, <a href="#page_313">313</a>.<br/>
+<i>Columnaria</i>, <a href="#page_105">105</a>;
+  <i>alveolata</i>, <a href="#page_105">105</a>.<br/>
+<i>Comatula</i>, <a href="#page_232">232</a>,
+  <a href="#page_266">266</a>.<br/>
+Conclusions to be drawn from Fossils,
+  <a href="#page_52">52-56</a>.<br/>
+Concretions, calcareous, <a href="#page_29">29</a>;
+  phosphatic, <a href="#page_31">31</a>; of clay-ironstone,
+  <a href="#page_31">31</a>; of manganese,
+  <a href="#page_31">31</a>.<br/>
+Conglomerate, <a href="#page_18">18</a>.<br/>
+<i>Coniferœ</i>, <a href="#page_262">262</a>;
+  wood of, <a href="#page_13">13</a>; of Devonian period,
+  <a href="#page_138">138</a>; of the Carboniferous,
+  <a href="#page_170">170</a>; of the Permian,
+  <a href="#page_196">196</a>; of the Trias,
+  <a href="#page_208">208</a>; of the Jurassic period,
+  <a href="#page_230">230</a>.<br/>
+Coniston Flags and Grits, <a href="#page_116">116</a>.<br/>
+Connecticut Sandstones, footprints of,
+  <a href="#page_222">222</a>, <a href="#page_346">346</a>.<br/>
+<i>Conocoryphe Mathewi</i>, <a href="#page_85">85</a>;
+  <i>Sultzeri</i>, <a href="#page_85">85</a>.<br/>
+Conodonts, <a href="#page_114">114</a>,
+  <a href="#page_131">131</a>.<br/>
+<i>Constellaria</i>, <a href="#page_105">105</a>.<br/>
+Constricting serpents of the Eocene,
+  <a href="#page_296">296</a>.<br/>
+Contemporaneity of strata, <a href="#page_44">44-46</a>.<br/>
+Continuity, theory of, <a href="#page_5">5-7</a>.<br/>
+<i>Conularia</i>, <a href="#page_111">111</a>,
+  <a href="#page_129">129</a>, <a href="#page_148">148</a>,
+  <a href="#page_186">186</a>, <a href="#page_199">199</a>,
+  <a href="#page_237">237</a>; <i>ornata</i>,
+  <a href="#page_149">149</a>.<br/>
+<i>Conulus</i>, <a href="#page_186">186</a>.<br/>
+<i>Conus</i>, <a href="#page_293">293</a>.<br/>
+Coomhola Grits, <a href="#page_158">158</a>,
+  <a href="#page_159">159</a>.<br/>
+Coprolites, <a href="#page_31">31</a>,
+  <a href="#page_243">243</a>.<br/>
+Coralline Crag, <a href="#page_324">324</a>.<br/>
+Corallines, <a href="#page_25">25</a>.<br/>
+<i>Corallium</i>, <a href="#page_311">311</a>.<br/>
+Coral-rag, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>, <a href="#page_230">230</a>.<br/>
+Coral-reefs, <a href="#page_24">24-26</a>.<br/>
+Coral-rock, <a href="#page_26">26</a>.<br/>
+Coral-sand, <a href="#page_19">19</a>,
+  <a href="#page_26">26</a>.<br/>
+Corals, <a href="#page_103">103</a>; of the Lower Silurian,
+  <a href="#page_104">104</a>; of the Upper Silurian,
+  <a href="#page_119">119</a>; of the Devonian,
+  <a href="#page_140">140-143</a>; of the Carboniferous,
+  <a href="#page_172">172-175</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_209">209</a>; of the Jurassic,
+  <a href="#page_230">230</a>, <a href="#page_231">231</a>;
+  of the Cretaceous, <a href="#page_266">266</a>;
+  of the Eocene, <a href="#page_292">292</a>; of the
+  Miocene, <a href="#page_311">311</a>.<br/>
+<i>Corbula</i>, <a href="#page_235">235</a>.<br/>
+Cornbrash, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+Corniferous Limestone, <a href="#page_135">135</a>,
+  <a href="#page_137">137</a>.<br/>
+<i>Cornulites</i>, <a href="#page_123">123</a>.<br/>
+Cornus, <a href="#page_262">262</a>.<br/>
+<i>Coryphodon</i>, <a href="#page_300">300</a>.<br/>
+Cowries, <a href="#page_259">259</a>,
+  <a href="#page_271">271</a>, <a href="#page_293">293</a>.<br/>
+Crabs, <a href="#page_180">180</a>, <a href="#page_197">197</a>,
+  <a href="#page_233">233</a>, <a href="#page_267">267</a>.<br/>
+Crag, Red, <a href="#page_324">324</a>; White,
+  <a href="#page_324">324</a>; Norwich,
+  <a href="#page_324">324</a>; Antwerp,
+  <a href="#page_325">325</a>; Bridlington,
+  <a href="#page_325">325</a>; Coralline,
+  <a href="#page_324">324</a>.<br/>
+<i>Crania</i>, <a href="#page_110">110</a>,
+  <a href="#page_127">127</a>, <a href="#page_198">198</a>,
+  <a href="#page_269">269</a>; <i>Ignabergensis</i>,
+  <a href="#page_269">269</a>.<br/>
+<i>Crassatella</i>, <a href="#page_292">292</a>.<br/>
+<i>Crepidophyllum</i>, <a href="#page_142">142</a>;
+  <i>Archiaci</i>, <a href="#page_142">142</a>.<br/>
+Cretaceous period, <a href="#page_256">256-283</a>;
+  rocks of, in Britain, <a href="#page_257">257-259</a>;
+  in North America, <a href="#page_260">260</a>,
+  <a href="#page_261">261</a>; life of,
+  <a href="#page_261">261-283</a>.<br/>
+Crinoidal Limestone, <a href="#page_24">24</a>,
+  <a href="#page_25">25</a>.<br/>
+<i>Crinoidea</i>, <a href="#page_120">120</a>; of the Cambrian,
+  <a href="#page_82">82</a>; of the Lower Silurian,
+  <a href="#page_105">105</a>; of the Upper Silurian,
+  <a href="#page_120">120-122</a>; of the Devonian,
+  <a href="#page_143">143</a>; of the Carboniferous,
+  <a href="#page_175">175</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Triss,
+  <a href="#page_209">209</a>; of the Jurassic,
+  <a href="#page_231">231</a>; of the Cretaceous,
+  <a href="#page_266">266</a>; of the Eocene,
+  <a href="#page_292">292</a>.<br/>
+<i>Crioceras</i>, <a href="#page_273">273</a>;
+  <i>cristatum</i>, <a href="#page_274">274</a>.<br/>
+<i>Crocodilia</i>, <a href="#page_218">218</a>; of the Trias,
+  <a href="#page_218">218</a>; of the Jurassic,
+  <a href="#page_251">251</a>; of the Cretaceous,
+  <a href="#page_280">280</a>; of the Eocene,
+  <a href="#page_296">296</a>, <a href="#page_297">297</a>.<br/>
+Cromer Forest-bed, <a href="#page_336">336</a>.<br/>
+<i>Crossozamites</i>, <a href="#page_230">230</a>.<br/>
+<i>Crotalocrinus</i>, <a href="#page_122">122</a>.<br/>
+<a name="page_399"><span class="page">Page 399</span></a>
+<i>Crustacea</i>, of the Cambrian, <a href="#page_83">83-87</a>;
+  of the Lower Silurian, <a href="#page_107">107</a>,
+  <a href="#page_108">108</a>; of the Upper Silurian,
+  <a href="#page_123">123-125</a>; of the Devonian,
+  <a href="#page_144">144</a>; of the Carboniferous,
+  <a href="#page_178">178-181</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_210">210</a>; of the Jurassic,
+  <a href="#page_233">233</a>; of the Cretaceous,
+  <a href="#page_267">267</a>.<br/>
+Cryptogams, <a href="#page_164">164</a>,
+  <a href="#page_262">262</a>.<br/>
+<i>Ctenacanthus</i>, <a href="#page_188">188</a>.<br/>
+<i>Ctenodonta</i>, <a href="#page_111">111</a>.<br/>
+<i>Cupressus</i>, <a href="#page_262">262</a>.<br/>
+Cursores, <a href="#page_297">297</a>,
+  <a href="#page_346">346</a>.<br/>
+Cuttle-fishes (<i>see</i> Dibranchiate Cephalopods).<br/>
+<i>Cyathocrinus</i>, <a href="#page_175">175</a>.<br/>
+<i>Cyathophyllum</i>, <a href="#page_119">119</a>,
+  <a href="#page_142">142</a>, <a href="#page_173">173</a>.<br/>
+<i>Cycadopteris</i>, <a href="#page_262">262</a>.<br/>
+Cycads, <a href="#page_208">208</a>; of the Carboniferous,
+  <a href="#page_170">170</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_208">208</a>; of the Jurassic,
+  <a href="#page_230">230</a>; of the Cretaceous,
+  <a href="#page_261">261</a>.<br/>
+<i>Cyclas</i>, <a href="#page_268">268</a>.<br/>
+<i>Cyclonema</i>, <a href="#page_129">129</a>.<br/>
+<i>Cyclophthalmus senior</i>, <a href="#page_181">181</a>.<br/>
+<i>Cyclostoma</i>, <a href="#page_294">294</a>;
+  <i>Arnoudii</i>, <a href="#page_294">294</a>.<br/>
+<i>Cynodraco</i>, <a href="#page_220">220</a>.<br/>
+<i>Cyprœa</i>, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>; <i>elegans</i>,
+  <a href="#page_393">393</a>.<br/>
+Cypress, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>, <a href="#page_311">311</a>.<br/>
+<i>Cypridina</i>, <a href="#page_145">145</a>.<br/>
+Cypridina Slates, <a href="#page_145">145</a>.<br/>
+<i>Cyrena</i>, <a href="#page_235">235</a>,
+  <a href="#page_268">268</a>, <a href="#page_292">292</a>.<br/>
+<i>Cyrtina</i>, <a href="#page_213">213</a>,
+  <a href="#page_214">214</a>.<br/>
+<i>Cyrtoceras</i>, <a href="#page_114">114</a>.<br/>
+<i>Cystiphyllum</i>, <a href="#page_119">119</a>,
+  <a href="#page_142">142</a>, <a href="#page_173">173</a>;
+  <i>vesiculosum</i>, <a href="#page_141">141</a>.<br/>
+<i>Cystoidea</i>, <a href="#page_105">105-107</a>; of the
+  Cambrian, <a href="#page_82">82</a>; of the Lower Silurian,
+  <a href="#page_106">106</a>; of the Upper Silurian,
+  <a href="#page_120">120</a>.
+</p>
+
+<p class="index">
+Dachstein Beds, <a href="#page_205">205</a>,
+  <a href="#page_206">206</a>.<br/>
+<i>Dadoxylon</i>, <a href="#page_138">138</a>,
+  <a href="#page_170">170</a>.<br/>
+<i>Daonella</i>, <a href="#page_211">211</a>;
+  <i>Lommelli</i>, <a href="#page_211">211</a>.<br/>
+<i>Dasornis Londinensis</i>, <a href="#page_297">297</a>.<br/>
+Decapod Crustaceans, <a href="#page_180">180</a>.<br/>
+Deer, <a href="#page_317">317</a>,
+  <a href="#page_329">329</a>, <a href="#page_354">354</a>.<br/>
+<i>Deinosauria</i>, <a href="#page_248">248</a>; of the Trias,
+  <a href="#page_221">221</a>; of the Jurassic,
+  <a href="#page_248">248-251</a>; of the Cretaceous,
+  <a href="#page_277">277-279</a>.<br/>
+<i>Deinotherium</i>, <a href="#page_319">319</a>,
+  <a href="#page_320">320</a>; <i>giganteum</i>,
+  <a href="#page_320">320</a>.<br/>
+Denbighshire Flags and Grits, <a href="#page_115">115</a>.<br/>
+<i>Dendrocrinus</i>, <a href="#page_82">82</a>.<br/>
+<i>Dendrograptus</i>, <a href="#page_100">100</a>.<br/>
+Desmids, <a href="#page_138">138</a>,
+  <a href="#page_262">262</a>.<br/>
+Devonian Formation, <a href="#page_133">133-136</a>; origin of
+  name, <a href="#page_133">133</a>; relation to Old Red
+  Sandstone, <a href="#page_133">133</a>,
+  <a href="#page_134">134</a>; of Devonshire,
+  <a href="#page_134">134</a>; of North America,
+  <a href="#page_135">135</a>, <a href="#page_136">136</a>;
+  life of, <a href="#page_136">136-156</a>.<br/>
+<i>Diadema</i>, <a href="#page_266">266</a>.<br/>
+Diatoms, <a href="#page_33">33</a>; of the Devonian,
+  <a href="#page_138">138</a>; of the Carboniferous,
+  <a href="#page_164">164</a>; of flints,
+  <a href="#page_261">261</a>; of Richmond Earth,
+  <a href="#page_33">33</a>, <a href="#page_307">307</a>.<br/>
+Dibranchiate Cephalopods, <a href="#page_112">112</a>;
+  of the Trias, <a href="#page_212">212</a>; of the Jurassic,
+  <a href="#page_239">239-241</a>; of the Cretaceous,
+  <a href="#page_274">274</a>, <a href="#page_275">275</a>;
+  of the Eocene, <a href="#page_294">294</a>; of the Miocene,
+  <a href="#page_312">312</a>.<br/>
+<i>Diceras</i>, <a href="#page_236">236</a>;
+  <i>arietina</i>, <a href="#page_236">236</a>.<br/>
+Diceras Limestone, <a href="#page_227">227</a>,
+  <a href="#page_236">236</a>.<br/>
+<i>Dichobune</i>, <a href="#page_303">303</a>.<br/>
+<i>Dichograptus</i>, <a href="#page_101">101</a>;
+  <i>octobrachiatus</i>, <a href="#page_101">101</a>.<br/>
+Dicotyledonous plants, <a href="#page_262">262</a>.<br/>
+<i>Dicotyles antiquus</i>, <a href="#page_317">317</a>.<br/>
+<i>Dicranograptus</i>, <a href="#page_101">101</a>,
+  <a href="#page_119">119</a>.<br/>
+<i>Dictyonema</i>, <a href="#page_89">89</a>,
+  <a href="#page_100">100</a>, <a href="#page_119">119</a>;
+  <i>sociale</i>, <a href="#page_89">89</a>.<br/>
+<i>Dicynodon</i>, <a href="#page_220">220</a>;
+  <i>lacerticeps</i>, <a href="#page_221">221</a>.<br/>
+<i>Didelphys</i>, <a href="#page_254">254</a>,
+  <a href="#page_315">315</a>; <i>gypsorum</i>,
+  <a href="#page_299">299</a>.<br/>
+<i>Didus ineptus</i>, <a href="#page_348">348</a>.<br/>
+<i>Didymograptus</i>, <a href="#page_101">101</a>;
+  <i>divaricatus</i>, <a href="#page_102">102</a>.<br/>
+<i>Dikellocephalus Celticus</i>, <a href="#page_84">84</a>;
+  <i>Minnesotensis</i>, <a href="#page_84">84</a>.<br/>
+<i>Dimorphodon</i>, <a href="#page_247">247</a>.<br/>
+<i>Dinichthys</i>, <a href="#page_153">153</a>;
+  <i>Hertzeri</i>, <a href="#page_151">151</a>.<br/>
+<i>Ditoceras</i>, <a href="#page_303">303</a>;
+  <i>mirabilis</i>, <a href="#page_304">304</a>.<br/>
+<i>Dinocerata</i>, <a href="#page_303">303</a>,
+  <a href="#page_304">304</a>.<br/>
+<i>Dinophis</i>, <a href="#page_296">296</a>.<br/>
+<i>Dinornis</i>, <a href="#page_346">346</a>,
+  <a href="#page_348">348</a>; <i>elephantopus</i>,
+  <a href="#page_346">346</a>; <i>giganteus</i>,
+  <a href="#page_346">346</a>.<br/>
+<i>Dinosauria</i> (see <i>Deinosauria</i>).<br/>
+<i>Dinotherium</i> (see <i>Deinotherium</i>).<br/>
+<i>Diphyphyllum</i>, <a href="#page_142">142</a>.<br/>
+<i>Diplograptus</i>, <a href="#page_101">101</a>,
+  <a href="#page_119">119</a>; <i>pristis</i>,
+  <a href="#page_102">102</a>.<br/>
+<i>Dipnoi</i>, <a href="#page_153">153</a>,
+  <a href="#page_187">187</a>, <a href="#page_215">215</a>.<br/>
+<i>Diprotodon</i>, <a href="#page_348">348</a>,
+  <a href="#page_349">349</a>; <i>australis</i>,
+  <a href="#page_348">348</a>.<br/>
+<i>Diptera</i>, <a href="#page_311">311</a>.<br/>
+<i>Discina</i>, <a href="#page_87">87</a>,
+  <a href="#page_110">110</a>, <a href="#page_127">127</a>,
+  <a href="#page_198">198</a>.<br/>
+<i>Discoidea</i>, <a href="#page_266">266</a>;
+  <i>cylindrica</i>, <a href="#page_267">267</a>.<br/>
+<i>Dithyrocaris</i>, <a href="#page_179">179</a>;
+  <i>Scouleri</i>, <a href="#page_180">180</a>.<br/>
+Dodo, <a href="#page_348">348</a>.<br/>
+Dog whelks.<br/>
+Dolomite, <a href="#page_293">293</a>.<br/>
+Dolomitic Couglomerate of Bristol, <a href="#page_201">201</a>,
+  <a href="#page_219">219</a>.<br/>
+Dolphins, <a href="#page_299">299</a>,
+  <a href="#page_315">315</a>.<br/>
+<i>Dorcatherium</i>, <a href="#page_317">317</a>.<br/>
+Downton Sandstone, <a href="#page_116">116</a>.<br/>
+<i>Draco volans</i>, <a href="#page_245">245</a>.<br/>
+Dragon-flies, <a href="#page_311">311</a>.<br/>
+Drift, Glacial, <a href="#page_337">337</a>.<br/>
+<i>Dremotherium</i>, <a href="#page_317">317</a>.<br/>
+<i>Dromatherium sylvestre</i>, <a href="#page_223">223</a>,
+  <a href="#page_224">224</a>.<br/>
+<i>Dryandra</i>, <a href="#page_262">262</a>.<br/>
+<i>Dryopithecus</i>, <a href="#page_323">323</a>.<br/>
+Dugougs, <a href="#page_299">299</a>.
+</p>
+
+<p class="index">
+<i>Echinodermata</i>, of the Cambrian,
+  <a href="#page_82">82</a>; of the Lower Silurian,
+  <a href="#page_105">105</a>; of the Upper Silurian,
+  <a href="#page_120">120</a>; of the Devonian,
+  <a href="#page_143">143</a>; of the Carboniferous,
+  <a href="#page_175">175</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_209">209</a>; of the Jurassic,
+  <a href="#page_231">231</a>; of the Cretaceous,
+  <a href="#page_266">266</a>; of the Eocene,
+  <a href="#page_292">292</a>.<br/>
+<i>Echinoidea</i>, <a href="#page_177">177</a>; of the Upper
+  Silurian, <a href="#page_120">120</a>; or the Devonian,
+  <a href="#page_143">143</a>; of the Carboniferous,
+  <a href="#page_177">177</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Jurassic,
+  <a href="#page_233">233</a>; of the Cretaceous,
+  <a href="#page_266">266</a>.<br/>
+<i>Edentata</i>, <a href="#page_349">349</a>;
+  of the Eocene, <a href="#page_299">299</a>;
+  of the Miocene, <a href="#page_315">315</a>;
+  of the Post-Pliocene, <a href="#page_349">349-353</a>.<br/>
+<i>Edriocrinus</i>, <a href="#page_122">122</a>.<br/>
+Eifel Limostone, <a href="#page_135">135</a>.<br/>
+<i>Elasmobranchii</i> (<i>See</i> Placoid Fishes).<br/>
+<i>Elasmosaurus</i>, <a href="#page_276">276</a>.<br/>
+Elephants, <a href="#page_319">319</a>,
+  <a href="#page_320">320</a>, <a href="#page_330">330</a>.<br/>
+<i>Elphas</i>, <a href="#page_320">320</a>;
+  <i>Americanus</i>, <a href="#page_357">357</a>;
+  <i>antiquus</i>, <a href="#page_329">329</a>,
+  <a href="#page_330">330</a>, <a href="#page_336">336</a>,
+  <a href="#page_341">341</a>, <a href="#page_357">357</a>;
+  <i>Falconeri</i>, <a href="#page_359">359</a>;
+  <i>Melitensis</i>, <a href="#page_359">359</a>;
+  <i>meridionalis</i>, <a href="#page_329">329</a>,
+  <a href="#page_330">330</a>, <a href="#page_336">336</a>,
+  <a href="#page_357">357</a>; <i>planifrons</i>,
+  <a href="#page_321">321</a>; <i>primigenius</i>,
+  <a href="#page_339">339</a>, <a href="#page_341">341</a>,
+  <a href="#page_357">357</a>, <a href="#page_358">358</a>.<br/>
+Elk, <a href="#page_354">354</a>; Irish,
+  <a href="#page_354">354</a>, <a href="#page_355">355</a>.<br/>
+<i>Ellipsocephalus Hoffi</i>, <a href="#page_84">84</a>.<br/>
+<i>Elotherium</i>, <a href="#page_317">317</a>.<br/>
+<i>Emydidœ</i>, <a href="#page_296">296</a>.<br/>
+<i>Emys</i>, <a href="#page_280">280</a>.<br/>
+Enaliosaurians, <a href="#page_219">219</a>,
+  <a href="#page_242">242</a>, <a href="#page_276">276</a>.<br/>
+Encrinital warble, <a href="#page_24">24</a>.<br/>
+<a name="page_400"><span class="page">Page 400</span></a>
+<i>Encrinurus</i>, <a href="#page_123">123</a>.<br/>
+<i>Encrinus liliiformis</i>, <a href="#page_209">209</a>,
+  <a href="#page_210">210</a>.<br/>
+Endogenous plants, <a href="#page_261">261</a>.<br/>
+<i>Endophyllum</i>, <a href="#page_173">173</a>.<br/>
+<i>Endothyra</i>, <a href="#page_171">171</a>;
+  <i>Bailyi</i>, <a href="#page_172">172</a>.<br/>
+Engis skull, <a href="#page_364">364</a>.<br/>
+<i>Entomis</i>, <a href="#page_145">145</a>.<br/>
+<i>Entomoconchus Scouleri</i>, <a href="#page_179">179</a>,
+  <a href="#page_180">180</a>.<br/>
+Eocene period, <a href="#page_284">284</a>; rocks of, in
+  Britain, <a href="#page_287">287</a>,
+  <a href="#page_288">288</a>; in France,
+  <a href="#page_288">288</a>; in North America,
+  <a href="#page_288">288</a>, <a href="#page_289">289</a>;
+  life of, <a href="#page_289">289, 305</a>.<br/>
+<i>Eocidaris</i>, <a href="#page_197">197</a>.<br/>
+<i>Eophyton</i>, <a href="#page_80">80</a>;
+  <i>Linneanum</i>, <a href="#page_81">81</a>.<br/>
+Eophyton Sandstone, <a href="#page_79">79</a>.<br/>
+<i>Eosaurus Acadianus</i>, <a href="#page_191">191</a>.<br/>
+Eozoic rocks, <a href="#page_67">67</a>.<br/>
+<i>Eozoön Bavaricum</i>, <a href="#page_76">76</a>.<br/>
+<i>Eozoön Canadense</i>, <a href="#page_68">68</a>,
+  <a href="#page_76">76</a>; appearance of, in mass,
+  <a href="#page_69">69</a>; minute structure of,
+  <a href="#page_70">70</a>, <a href="#page_71">71</a>;
+  affinities of, with <i>Foraminifera</i>,
+  <a href="#page_71">71-74</a>.<br/>
+<i>Ephemeridœ</i>, <a href="#page_145">145</a>,
+  <a href="#page_183">183</a>.<br/>
+<i>Equisetaceœ</i>, <a href="#page_166">166</a>.<br/>
+<i>Equisetites</i>, <a href="#page_196">196</a>.<br/>
+<i>Equidœ</i>, <a href="#page_301">301</a>,
+  <a href="#page_302">302</a>, <a href="#page_316">316</a>,
+  <a href="#page_328">328</a>.<br/>
+<i>Equus</i>, <a href="#page_302">302</a>; <i>caballus</i>,
+  <a href="#page_354">354</a>; <i>excelsus</i>,
+  <a href="#page_328">328</a>; <i>fossilis</i>,
+  <a href="#page_336">336</a>, <a href="#page_354">354</a>.<br/>
+<i>Eridophyllum</i>, <a href="#page_142">142</a>.<br/>
+<i>Eryon arctiformis</i>, <a href="#page_233">233</a>,
+  <a href="#page_234">234</a>.<br/>
+<i>Eschara</i>, <a href="#page_267">267</a>.<br/>
+<i>Escharidœ</i>, <a href="#page_267">267</a>.<br/>
+<i>Escharina</i>, <a href="#page_267">267</a>;
+  <i>Oceani</i>, <a href="#page_268">268</a>.<br/>
+<i>Estheria</i>, <a href="#page_145">145</a>,
+  <a href="#page_179">179</a>, <a href="#page_210">210</a>;
+  <i>tenella</i>, <a href="#page_180">180</a>.<br/>
+<i>Eucalyptocrinus</i>, <a href="#page_122">122</a>;
+  <i>polydactylus</i>, <a href="#page_122">122</a>.<br/>
+<i>Eucladia</i>, <a href="#page_120">120</a>.<br/>
+<i>Euomphalus</i>, <a href="#page_128">128</a>,
+  <a href="#page_148">148</a>, <a href="#page_186">186</a>,
+  <a href="#page_199">199</a>, <a href="#page_213">213</a>;
+  <i>discors</i>, <a href="#page_129">129</a>.<br/>
+<i>Euplectella</i>, <a href="#page_265">265</a>.<br/>
+<i>Euproöps</i>, <a href="#page_179">179</a>.<br/>
+European Bison, <a href="#page_356">356</a>.<br/>
+<i>Eurypterida</i>, <a href="#page_124">124</a>,
+  <a href="#page_179">179</a>; of the Upper Silurian,
+  <a href="#page_124">124</a>; of the Devonian,
+  <a href="#page_144">144</a>.<br/>
+Even-toed Ungulates, <a href="#page_300">300</a>,
+  <a href="#page_317">317</a>, <a href="#page_354">354</a>.<br/>
+Exogenous plants, <a href="#page_266">266</a>.<br/>
+<i>Exogyra</i>, <a href="#page_236">236</a>;
+  <i>virgula</i>, <a href="#page_236">236</a>.<br/>
+Extinction of species, <a href="#page_57">57</a>,
+  <a href="#page_58">58</a>.
+</p>
+
+<p class="index">
+<i>Fagus</i>, <a href="#page_262">262</a>.<br/>
+Faluns, <a href="#page_306">306</a>.<br/>
+Fan-palms, <a href="#page_308">308</a>.<br/>
+<i>Favistella</i>, <a href="#page_105">105</a>.<br/>
+<i>Favostites</i>, <a href="#page_119">119</a>,
+  <a href="#page_142">142</a>; <i>Gothlandica</i>,
+  <a href="#page_143">143</a>; <i>hemisphœrica</i>,
+  <a href="#page_143">143</a>.<br/>
+Faxöe Limestone, <a href="#page_259">259</a>,
+  <a href="#page_286">286</a>.<br/>
+<i>Felis angustus</i>, <a href="#page_330">330</a>;
+  <i>leo</i>, <a href="#page_361">361</a>; <i>spelœa</i>,
+  <a href="#page_361">361</a>.<br/>
+<i>Fenestella</i>, <a href="#page_108">108</a>,
+  <a href="#page_125">125</a>, <a href="#page_145">145</a>,
+  <a href="#page_184">184</a>, <a href="#page_198">198</a>,
+  <a href="#page_210">210</a>; <i>cribrosa</i>,
+  <a href="#page_146">146</a>; <i>magnifica</i>,
+  <a href="#page_146">146</a>; <i>retiformis</i>,
+  <a href="#page_198">198</a>.<br/>
+<i>Fenestellidœ</i>, <a href="#page_183">183</a>.<br/>
+Ferns, of the Devonian, <a href="#page_136">136</a>;
+  of the Carboniferous, <a href="#page_164">164</a>;
+  of the Permian, <a href="#page_196">196</a>; of the Trias,
+  <a href="#page_207">207</a>; of the Jurassic,
+  <a href="#page_229">229</a>; of the Cretaceous,
+  <a href="#page_261">261</a>.<br/>
+Fig-shells, <a href="#page_293">293</a>.<br/>
+Fishes, <a href="#page_150">150</a>; of the Upper Silurian,
+  <a href="#page_130">130</a>, <a href="#page_131">131</a>;
+  of the Devonian, <a href="#page_150">150-155</a>; of the
+  Carboniferous, <a href="#page_187">187</a>,
+  <a href="#page_188">188</a>; of the Permian,
+  <a href="#page_199">199</a>, <a href="#page_200">200</a>;
+  of the Trias, <a href="#page_214">214</a>,
+  <a href="#page_215">215</a>; of the Jurassic,
+  <a href="#page_240">240-242</a>; of the Cretaceous,
+  <a href="#page_275">275</a>, <a href="#page_276">276</a>; of
+  the Eocene, <a href="#page_295">295</a>,
+  <a href="#page_296">296</a>; of the Miocene,
+  <a href="#page_312">312</a>, <a href="#page_313">313</a>.<br/>
+Flint, <a href="#page_33">33</a>; structure of,
+  <a href="#page_34">34</a>; origin of, <a href="#page_34">34</a>;
+  organisms of, <a href="#page_34">34</a>,
+  <a href="#page_138">138</a>, <a href="#page_263">263</a>;
+  of Chalk, <a href="#page_34">34</a>, <a href="#page_259">259</a>,
+  <a href="#page_261">261</a>.
+  Human implements associated with bones of extinct Mammals,
+  <a href="#page_363">363</a>, <a href="#page_364">364</a>.<br/>
+Flora (<i>see</i> Plants).<br/>
+Footprints of <i>Cheirotherium</i>, <a href="#page_215">215</a>,
+  <a href="#page_216">216</a>; of the Triassic sandstones of
+  Connecticut, <a href="#page_222">222</a>.<br/>
+<i>Foraminifera</i>, <a href="#page_22">22-24</a>,
+  <a href="#page_71">71-74</a>; of the Cambrian,
+  <a href="#page_82">82</a>; of the Lower Silurian,
+  <a href="#page_98">98</a>; of the Carboniferous,
+  <a href="#page_171">171</a>, <a href="#page_172">172</a>;
+  of the Permian, <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_209">209</a>; of the Jurassic,
+  <a href="#page_230">230</a>; of the Cretaceous,
+  <a href="#page_21">21</a>, <a href="#page_22">22</a>,
+  <a href="#page_263">263</a>; of the Eocene,
+  <a href="#page_290">290</a>; of the Miocene,
+  <a href="#page_311">311</a>; of the Post-Pliocene,
+  <a href="#page_338">338</a>; of Atlantic ooze,
+  <a href="#page_22">22</a>, <a href="#page_23">23</a>; as
+  builders of limestone, <a href="#page_24">24</a>,
+  <a href="#page_25">25</a>, <a href="#page_28">28</a>;
+  as forming green sands, <a href="#page_34">34</a>.<br/>
+<i>Forbesiocrinus</i>, <a href="#page_175">175</a>.<br/>
+Forest-bed of Cromer, <a href="#page_336">336</a>.<br/>
+Forest-bugs, <a href="#page_311">311</a>.<br/>
+Forest-marble, <a href="#page_227">227</a>.<br/>
+Formation, definition of, <a href="#page_18">18</a>;
+  succession of, <a href="#page_42">42</a>.<br/>
+Fossiliferous rocks, <a href="#page_14">14-37</a>;
+  chronological succession of, <a href="#page_37">37-44</a>.<br/>
+Fossilisation, processes of, <a href="#page_11">11-14</a>.<br/>
+Fossils, definition of, <a href="#page_11">11</a>; distinctive,
+  of rock-groups, <a href="#page_38">38</a>; conclusions
+  to be drawn from, <a href="#page_52">52-56</a>; biological
+  relations of, <a href="#page_57">57-61</a>.<br/>
+Foxes, <a href="#page_304">304</a>.<br/>
+Fringe-finned Ganoids, <a href="#page_153">153</a>.<br/>
+Fucoidal Sandstone, <a href="#page_79">79</a>,
+  <a href="#page_80">80</a>.<br/>
+Fucoids, <a href="#page_80">80</a>, <a href="#page_97">97</a>.<br/>
+Fuller's Earth, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+<i>Fusulina</i>, <a href="#page_172">172</a>; <i>cylindrica</i>,
+  <a href="#page_172">172</a>.<br/>
+<i>Fusus</i>, <a href="#page_237">237</a>,
+  <a href="#page_293">293</a>.
+</p>
+
+<p class="index">
+<i>Galeocerdo</i>, <a href="#page_312">312</a>.<br/>
+<i>Galerites</i>, <a href="#page_266">266</a>;
+  <i>albo-galerus</i>, <a href="#page_267">267</a>.<br/>
+<i>Galestes</i>, <a href="#page_254">254</a>.<br/>
+Ganoid Fishes, <a href="#page_150">150</a>; of the Upper
+  Silurian, <a href="#page_130">130</a>; of the Devonian,
+  <a href="#page_150">150-153</a>; of the Carboniferous,
+  <a href="#page_187">187</a>, <a href="#page_188">188</a>;
+  of the Permian, <a href="#page_199">199</a>; of the Trias,
+  <a href="#page_214">214</a>; of the Jurassic,
+  <a href="#page_241">241</a>; of the Cretaceous,
+  <a href="#page_275">275</a>; of the Eocene,
+  <a href="#page_292">292</a>, <a href="#page_293">293</a>.<br/>
+Gaspé Beds, <a href="#page_134">134</a>.<br/>
+<i>Gasteropoda</i>, of the Cambrian, <a href="#page_88">88</a>;
+  of the Lower Silurian, <a href="#page_111">111</a>; of the
+  Upper Silurian, <a href="#page_128">128</a>,
+  <a href="#page_129">129</a>; of the Devonian,
+  <a href="#page_148">148</a>; of the Carboniferous,
+  <a href="#page_186">186</a>; of the Permian,
+  <a href="#page_199">199</a>; of the Trias,
+  <a href="#page_213">213</a>; of the Jurassic,
+  <a href="#page_236">236</a>, <a href="#page_237">237</a>;
+  of the Cretaceous, <a href="#page_271">271</a>; of the
+  Eocene, <a href="#page_292">292</a>,
+  <a href="#page_293">293</a>.<br/>
+<i>Gastornis Parisiensis</i>, <a href="#page_297">297</a>.<br/>
+Gault, <a href="#page_257">257</a>, <a href="#page_258">258</a>.<br/>
+Gavial, <a href="#page_251">251</a>, <a href="#page_297">297</a>.<br/>
+Genesee Slates, <a href="#page_135">135</a>.<br/>
+Geological record, breaks in the, <a href="#page_47">47-52</a>.<br/>
+Giraffes, <a href="#page_317">317</a>.<br/>
+Glacial period, <a href="#page_335">335</a>; deposits of,
+  <a href="#page_337">337</a>, <a href="#page_338">338</a>.<br/>
+<i>Glandulina</i>, <a href="#page_311">311</a>.<br/>
+Glauconite, <a href="#page_34">34</a>, <a href="#page_74">74</a>,
+  <a href="#page_98">98</a>, <a href="#page_263">263</a>.<br/>
+<i>Glauconome</i>, <a href="#page_126">126</a>,
+  <a href="#page_184">184</a>; <i>pulcherrima</i>,
+  <a href="#page_183">183</a>.<br/>
+Globe Crinoids (<i>see</i> Cystoidea).<br/>
+<i>Globigerina</i>, <a href="#page_22">22</a>,
+  <a href="#page_23">23</a>, <a href="#page_264">264</a>.<br/>
+Glutton, <a href="#page_360">360</a>.<br/>
+<i>Glyptaster</i>, <a href="#page_120">120</a>.<br/>
+<i>Glyptocrinus</i>, <a href="#page_122">122</a>.<br/>
+<i>Glyptodon</i>, <a href="#page_351">351</a>,
+  <a href="#page_352">352</a>; <i>clavipes</i>,
+  <a href="#page_352">352</a>.<br/>
+<i>Glyptolœmus</i>, <a href="#page_153">153</a>.<br/>
+Goats, <a href="#page_318">318</a>.<br/>
+<i>Goniatites</i>, <a href="#page_130">130</a>,
+  <a href="#page_149">149</a>, <a href="#page_187">187</a>,
+  <a href="#page_214">214</a>; <i>Jossœ</i>,
+  <a href="#page_187">187</a>.<br/>
+<a name="page_401"><span class="page">Page 401</span></a>
+<i>Gorgonidœ</i>, <a href="#page_292">292</a>.<br/>
+<i>Grallatores</i>, <a href="#page_297">297</a>.<br/>
+Graphite, <a href="#page_36">36</a>; mode of occurrence of,
+  <a href="#page_36">36</a>, <a href="#page_68">68</a>; origin of,
+  <a href="#page_36">36</a>.<br/>
+<i>Graptolites</i>, <a href="#page_89">89</a>,
+  <a href="#page_100">100</a>; structure of,
+  <a href="#page_100">100</a>; of the Lower Silurian,
+  <a href="#page_100">100-103</a>; of the Upper Silurian,
+  <a href="#page_118">118</a>, <a href="#page_119">119</a>.<br/>
+Great Oolite, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>; Upper, <a href="#page_257">257</a>,
+  <a href="#page_258">258</a>, <a href="#page_260">260</a>.<br/>
+Greenland. Miocene plants of, <a href="#page_311">311</a>.<br/>
+Greensand, Lower, <a href="#page_257">257</a>.<br/>
+Green sands, origin of, <a href="#page_44">44</a>,
+  <a href="#page_263">263</a>.<br/>
+<i>Grevillea</i>, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>.<br/>
+<i>Griffithides</i>, <a href="#page_197">197</a>.<br/>
+Grizzly Bear, <a href="#page_359">359</a>.<br/>
+Groond Sloths, <a href="#page_351">351</a>.<br/>
+<i>Gryphœa</i>, <a href="#page_236">236</a>;
+  <i>incurva</i>, <a href="#page_236">236</a>.<br/>
+Guelph Limestone, <a href="#page_117">117</a>.<br/>
+<i>Gulo luscus</i>, <a href="#page_360">360</a>;
+  <i>spelœus</i>, <a href="#page_360">360</a>.<br/>
+Guttenstein Beds, <a href="#page_205">205</a>,
+  <a href="#page_206">206</a>.<br/>
+Gymnospermous Exogens, <a href="#page_262">262</a>.<br/>
+Gypsum, <a href="#page_32">32</a>, <a href="#page_193">193</a>,
+  <a href="#page_204">204</a>.<br/>
+<i>Gyracanthus</i>, <a href="#page_188">188</a>.<br/>
+<i>Gyroceras</i>, <a href="#page_130">130</a>.
+</p>
+
+<p class="index">
+<i>Hadrosaurus</i>, <a href="#page_278">278</a>.<br/>
+<i>Halitherium</i>, <a href="#page_299">299</a>.<br/>
+Hallstadt Beds, <a href="#page_205">205</a>,
+  <a href="#page_206">206</a>.<br/>
+<i>Halobia</i>, <a href="#page_211">211</a>.<br/>
+<i>Halysites</i>, <a href="#page_119">119</a>;
+  <i>agglomerata</i>, <a href="#page_120">120</a>;
+  <i>catenularia</i>, <a href="#page_120">120</a>.<br/>
+Hamilton formation, <a href="#page_135">135</a>,
+  <a href="#page_137">137</a>.<br/>
+<i>Hamites</i>, <a href="#page_273">273</a>;
+  <i>rotundus</i>, <a href="#page_274">274</a>.<br/>
+<i>Haplophlebium Barnesi</i>, <a href="#page_182">182</a>.<br/>
+Harlech Grits, <a href="#page_78">78</a>,
+  <a href="#page_79">79</a>.<br/>
+<i>Harpes</i>, <a href="#page_108">108</a>,
+  <a href="#page_123">123</a>; <i>ungula</i>,
+  <a href="#page_124">124</a>.<br/>
+Hastings Sands, <a href="#page_257">257</a>.<br/>
+Headon and Osborne series, <a href="#page_287">287</a>,
+  <a href="#page_288">288</a>.<br/>
+Heart-urchins, <a href="#page_311">311</a>.<br/>
+<i>Heliolites</i>, <a href="#page_105">105</a>,
+  <a href="#page_119">119</a>, <a href="#page_266">266</a>.<br/>
+<i>Heliophyllum</i>, <a href="#page_142">142</a>,
+  <a href="#page_173">173</a>; <i>exiguum</i>,
+  <a href="#page_141">141</a>.<br/>
+<i>Helix</i>, <a href="#page_294">294</a>.<br/>
+<i>Helladotherium</i>, <a href="#page_317">317</a>.<br/>
+<i>Helopora fragilis</i>, <a href="#page_126">126</a>.<br/>
+<i>Hemicidaris crenularis</i>, <a href="#page_233">233</a>.<br/>
+<i>Hemiptera</i>, <a href="#page_311">311</a>.<br/>
+<i>Hemitrochiscus paradoxus</i>, <a href="#page_197">197</a>.<br/>
+Hempstead Beds, <a href="#page_306">306</a>.<br/>
+<i>Hesperornis</i>, <a href="#page_281">281</a>,
+  <a href="#page_282">282</a>; <i>regalis</i>,
+  <a href="#page_282">282</a>.<br/>
+<i>Heteropoda</i>, <a href="#page_111">111</a>;
+  of the Lower Silurian, <a href="#page_111">111</a>;
+  of the Upper Silurian, <a href="#page_129">129</a>;
+  of the Devonian, <a href="#page_148">148</a>;
+  of the Carboniferous, <a href="#page_186">186</a>.<br/>
+<i>Hinnites</i>, <a href="#page_213">213</a>.<br/>
+<i>Hipparion</i>, <a href="#page_301">301</a>,
+  <a href="#page_302">302</a>, <a href="#page_316">316</a>,
+  <a href="#page_317">317</a>, <a href="#page_328">328</a>.<br/>
+<i>Hippopodium</i>, <a href="#page_235">235</a>.<br/>
+<i>Hippopotamus</i>, <a href="#page_302">302</a>;
+  <i>amphibus</i>, <a href="#page_317">317</a>,
+  <a href="#page_329">329</a>; <i>major</i>,
+  <a href="#page_329">329</a>, <a href="#page_336">336</a>,
+  <a href="#page_354">354</a>; <i>Sivalensis</i>,
+  <a href="#page_318">318</a>.<br/>
+<i>Hippothoa</i>, <a href="#page_108">108</a>.<br/>
+Hippurite Marble, <a href="#page_270">270</a>.<br/>
+<i>Hippurites</i>, <a href="#page_270">270</a>;
+  <i>Toucasiana</i>, <a href="#page_271">271</a>.<br/>
+<i>Hippuritidœ</i>, <a href="#page_270">270</a>,
+  <a href="#page_285">285</a>.<br/>
+<i>Histioderma</i>, <a href="#page_82">82</a>.<br/>
+Hollow-horned Ruminants, <a href="#page_317">317</a>.<br/>
+<i>Holocystis elegan</i>, <a href="#page_266">266</a>.<br/>
+<i>Holopea</i>, <a href="#page_129">129</a>;
+  <i>Subconica</i>, <a href="#page_129">129</a>.<br/>
+<i>Holopella</i>, <a href="#page_129">129</a>,
+  <a href="#page_213">213</a>; <i>obsoleta</i>,
+  <a href="#page_129">129</a>.<br/>
+<i>Holoptychius</i>, <a href="#page_153">153</a>;
+  <i>nobilissimus</i>, <a href="#page_154">154</a>.<br/>
+Holostomatous Univalves, <a href="#page_236">236</a>,
+  <a href="#page_293">293</a>.<br/>
+Holothurians, <a href="#page_120">120</a>.<br/>
+<i>Holtenia</i>, <a href="#page_264">264</a>.<br/>
+<i>Homacanthus</i>, <a href="#page_188">188</a>.<br/>
+<i>Homalonotus</i>, <a href="#page_123">123</a>,
+  <a href="#page_145">145</a>; <i>armatus</i>,
+  <a href="#page_144">144</a>.<br/>
+<i>Homo diluvii testis</i>, <a href="#page_313">313</a>.<br/>
+Honeycomb Corals, <a href="#page_142">142</a>.<br/>
+Hoofed Quadrupeds, <a href="#page_300">300</a>.<br/>
+Hudson River Group, <a href="#page_95">95</a>.<br/>
+Huronian Period, <a href="#page_75">75</a>,
+  <a href="#page_76">76</a>; rocks of,
+  <a href="#page_75">75</a>.<br/>
+<i>Hyœna crocuta</i>, <a href="#page_360">360</a>;
+  <i>spelœa</i>, <a href="#page_360">360</a>;
+  <i>Hipparionum</i>, <a href="#page_330">330</a>.<br/>
+<i>Hyœnictis</i>, <a href="#page_322">322</a>.<br/>
+<i>Hyœnodon</i>, <a href="#page_304">304</a>.<br/>
+<i>Hyalea D'Orbignyana</i>, <a href="#page_312">312</a>.<br/>
+<i>Hybodus</i>, <a href="#page_214">214</a>,
+  <a href="#page_242">242</a>, <a href="#page_275">275</a>.<br/>
+<i>Hydractinia</i>, <a href="#page_265">265</a>.<br/>
+Hydroid Zoophytes, <a href="#page_103">103</a>,
+  <a href="#page_265">265</a>.<br/>
+<i>Hymenocaris vermicauda</i>, <a href="#page_84">84</a>,
+  <a href="#page_88">88</a>.<br/>
+<i>Hymenophyllites</i>, <a href="#page_165">165</a>.<br/>
+<i>Hymenoptera</i>, <a href="#page_311">311</a>.<br/>
+<i>Hyopotamus</i>, <a href="#page_302">302</a>.<br/>
+<i>Hyperodapedon</i>, <a href="#page_218">218</a>.<br/>
+<i>Hypsiprymnopsis</i>, <a href="#page_224">224</a>.<br/>
+<i>Hystrix primigenius</i>, <a href="#page_322">322</a>.
+</p>
+
+<p class="index">
+<i>Ichthyocrinus lœvis</i>, <a href="#page_122">122</a>.<br/>
+<i>Ichthyornis</i>, <a href="#page_281">281</a>,
+  <a href="#page_282">282</a>; <i>dispar</i>,
+  <a href="#page_281">281</a>, <a href="#page_282">282</a>.<br/>
+<i>Ichthyosaurus</i>, <a href="#page_242">242</a>,
+  <a href="#page_243">243</a>, <a href="#page_276">276</a>;
+  <i>communis</i>, <a href="#page_242">242</a>.<br/>
+<i>Ictitherium</i>, <a href="#page_322">322</a>.<br/>
+<i>Iguana</i>, <a href="#page_277">277</a>.<br/>
+<i>Iguanodon</i>, <a href="#page_277">277</a>,
+  <a href="#page_278">278</a>; <i>Mantelli</i>,
+  <a href="#page_278">278</a>.<br/>
+Ilfracombe Group, <a href="#page_134">134</a>.<br/>
+<i>Illœnus</i>, <a href="#page_108">108</a>,
+  <a href="#page_123">123</a>.<br/>
+Imperfection of the palæontological record,
+  <a href="#page_50">50</a>, <a href="#page_51">51</a>.<br/>
+Inferior Oolite, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+Infusorial Earth, <a href="#page_33">33</a>.<br/>
+<i>Inoceramus</i>, <a href="#page_269">269</a>; <i>sulcatus</i>,
+  <a href="#page_270">270</a>.<br/>
+<i>Insectivora</i>, of the Eocene, <a href="#page_305">305</a>;
+  of the Miocene, <a href="#page_322">322</a>.<br/>
+Insects, of the Devonian, <a href="#page_145">145</a>; of the
+  Carboniferous, <a href="#page_182">182</a>; of the Jurassic,
+  <a href="#page_233">233</a>; of the Miocene,
+  <a href="#page_311">311</a>, <a href="#page_312">312</a>.<br/>
+Irish Elk, <a href="#page_354">354</a>,
+  <a href="#page_355">355</a>.<br/>
+<i>Ischadites</i>, <a href="#page_99">99</a>,
+  <a href="#page_118">118</a>.<br/>
+Isopod Crustaceans, <a href="#page_84">84</a>.
+</p>
+
+<p class="index">
+Jackson Beds, <a href="#page_289">289</a>.<br/>
+Jurassic period, <a href="#page_226">226</a>; rocks of,
+  <a href="#page_226">226-229</a>; life of,
+  <a href="#page_229">229-255</a>.
+</p>
+
+<p class="index">
+<i>Kaidacarpum</i>, <a href="#page_230">230</a>.<br/>
+Kainozoic period, <a href="#page_44">44</a>,
+  <a href="#page_284">284-287</a>.<br/>
+Kangaroo, <a href="#page_348">348</a>.<br/>
+Kelloway Rock, <a href="#page_227">227</a>.<br/>
+Kent's Cavern, deposits in, <a href="#page_343">343</a>.<br/>
+Keuper, <a href="#page_204">204</a>,
+  <a href="#page_206">206</a>.<br/>
+Kimmeridge Clay, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+King-crabs, <a href="#page_84">84</a>,
+  <a href="#page_124">124</a>, <a href="#page_125">125</a>,
+  <a href="#page_179">179</a>.<br/>
+<i>Koninckia</i>, <a href="#page_213">213</a>,
+  <a href="#page_214">214</a>.<br/>
+Kössen Beds, <a href="#page_205">205</a>,
+  <a href="#page_206">206</a>.
+</p>
+
+<p class="index">
+<i>Labyrinthodon Jœgeri</i>, <a href="#page_217">217</a>.<br/>
+<i>Labyrinthodontia</i>, <a href="#page_290">290</a>; of the
+  Carboniferous, <a href="#page_189">189-191</a>; of the Permian,
+  <a href="#page_200">200</a>; of the Trias,
+  <a href="#page_215">215-217</a>.<br/>
+Lace-corals, <a href="#page_108">108</a>,
+  <a href="#page_125">125</a>, <a href="#page_145">145</a>,
+  <a href="#page_183">183</a>, <a href="#page_198">198</a>,
+  <a href="#page_210">210</a>.<br/>
+<i>Lacertilia</i>, <a href="#page_202">202</a>; of the Permian,
+  <a href="#page_201">201</a>, <a href="#page_202">202</a>;
+  of the Trias, <a href="#page_217">217</a>,
+  <a href="#page_218">218</a>; of the Jurassic,
+  <a href="#page_251">251</a>; of the Cretaceous,
+  <a href="#page_280">280</a>.<br/>
+<i>Lœlaps</i>, <a href="#page_278">278</a>.<br/>
+<i>Lamellibranchiata</i>, of the Cambrian,
+  <a href="#page_88">88</a>; of the Lower Silurian,
+  <a href="#page_110">110</a>; of the Upper Silurian,
+  <a href="#page_128">128</a>; of the Devonian,
+<a name="page_402"><span class="page">Page 402</span></a>
+  <a href="#page_148">148</a>; of the Carboniferous,
+  <a href="#page_186">186</a>; of the Permian,
+  <a href="#page_198">198</a>; of the Trias,
+  <a href="#page_211">211</a>; of the Jurassic,
+  <a href="#page_234">234-236</a>; of the Cretaceous,
+  <a href="#page_268">268-270</a>; of the Eocene,
+  <a href="#page_292">292</a>.<br/>
+<i>Lamna</i>, <a href="#page_275">275</a>,
+  <a href="#page_312">312</a>.<br/>
+Lamp-shells (see <i>Brachiopoda</i>).<br/>
+Land-tortoises, <a href="#page_313">313</a>.<br/>
+<i>Lauraceœ</i>, <a href="#page_308">308</a>.<br/>
+Laurentian period, <a href="#page_65">65</a>; rocks of,
+  <a href="#page_65">65</a>, <a href="#page_66">66</a>;
+  Lower Laurentian, <a href="#page_66">66</a>; Upper
+  Laurentian, <a href="#page_66">66</a>; areas occupied by
+  Laurentian rocks, <a href="#page_66">66</a>; limestones of,
+  <a href="#page_66">66</a>; iron-ores of,
+  <a href="#page_68">68</a>; phosphate of lime of,
+  <a href="#page_68">68</a>; graphite of,
+  <a href="#page_68">68</a>; life of,
+  <a href="#page_67">67-75</a>.<br/>
+Leaf-beds of the Isle of Mull, <a href="#page_306">306</a>.<br/>
+<i>Leda</i>, <a href="#page_292">292</a>; <i>truncata</i>,
+  <a href="#page_338">338</a>.<br/>
+<i>Leguminosites Marcouanus</i>, <a href="#page_263">263</a>.<br/>
+Lemming, <a href="#page_344">344</a>,
+  <a href="#page_345">345</a>.<br/>
+<i>Lepadidœ</i>, <a href="#page_267">267</a>.<br/>
+<i>Lepadocrinus Gebhardi</i>, <a href="#page_106">106</a>.<br/>
+<i>Leperditia</i>, <a href="#page_108">108</a>;
+  <i>canadensis</i>, <a href="#page_107">107</a>.<br/>
+<i>Lepidaster</i>, <a href="#page_120">120</a>.<br/>
+<i>Lepidechinus</i>, <a href="#page_178">178</a>.<br/>
+<i>Lepidesthes</i>, <a href="#page_178">178</a>.<br/>
+Lepidodendroids, <a href="#page_166">166</a>,
+  <a href="#page_167">167</a>, <a href="#page_207">207</a>.<br/>
+<i>Lepidodendron</i>, <a href="#page_118">118</a>,
+  <a href="#page_136">136</a>, <a href="#page_166">166</a>,
+  <a href="#page_196">196</a>; <i>Sternberg</i>,
+  <a href="#page_167">167</a>.<br/>
+<i>Lepidoptera</i>, <a href="#page_311">311</a>.<br/>
+<i>Lepidosiren</i>, <a href="#page_153">153</a>.<br/>
+<i>Lepidosteus</i>, <a href="#page_188">188</a>.<br/>
+<i>Lepidostrobus</i>, <a href="#page_166">166</a>.<br/>
+<i>Lepidotus</i>, <a href="#page_275">275</a>.<br/>
+<i>Leptœna</i>, <a href="#page_109">109</a>,
+  <a href="#page_110">110</a>, <a href="#page_125">125</a>,
+  <a href="#page_234">234</a>; <i>Liassica</i>,
+  <a href="#page_235">235</a>; <i>sericea</i>,
+  <a href="#page_110">110</a>.<br/>
+<i>Leptocœlia</i>, <a href="#page_127">127</a>;
+  <i>plano-convexa</i>, <a href="#page_127">127</a>.<br/>
+Lias, <a href="#page_226">226</a>, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+Lichas, <a href="#page_108">108</a>.<br/>
+<i>Licrophycus Ottawaensis</i>, <a href="#page_97">97</a>.<br/>
+Lignitic Formation of North America,
+  <a href="#page_288">288</a>, <a href="#page_297">297</a>.<br/>
+Lily-encrinite, <a href="#page_209">209</a>,
+  <a href="#page_210">210</a>.<br/>
+<i>Lima</i>, <a href="#page_235">235</a>.<br/>
+Lime, phosphate of, <a href="#page_30">30</a>,
+  <a href="#page_31">31</a>.<br/>
+Limestone, <a href="#page_23">23-27</a>; varieties of,
+  <a href="#page_27">27-30</a>; origin of,
+  <a href="#page_21">21</a>; microscopical structure of,
+  <a href="#page_26">26</a>; Crinoidal, <a href="#page_24">24</a>;
+  Foraminiferal, <a href="#page_24">24</a>,
+  <a href="#page_26">26</a>; coralline,
+  <a href="#page_24">24</a>; magnesian, <a href="#page_27">27</a>;
+  metamorphic, <a href="#page_27">27</a>; oolitic,
+  <a href="#page_28">28-30</a>; pisolitic,
+  <a href="#page_29">29</a>; bituminous, <a href="#page_36">36</a>;
+  Laurentian, <a href="#page_67">67</a>.<br/>
+<i>Limnœa</i>, <a href="#page_294">294</a>;
+  <i>pyramidalis</i>, <a href="#page_294">294</a>.<br/>
+<i>Limulus</i>, <a href="#page_84">84</a>,
+  <a href="#page_124">124</a>, <a href="#page_125">125</a>,
+  <a href="#page_179">179</a>.<br/>
+<i>Lingula</i>, <a href="#page_87">87</a>,
+  <a href="#page_88">88</a>, <a href="#page_110">110</a>,
+  <a href="#page_127">127</a>, <a href="#page_147">147</a>,
+  <a href="#page_198">198</a>; <i>Credneri</i>,
+  <a href="#page_198">198</a>.<br/>
+Lingula Flags, <a href="#page_77">77</a>,
+  <a href="#page_78">78</a>, <a href="#page_79">79</a>,
+  <a href="#page_88">88</a>.<br/>
+<i>Lingulella</i>, <a href="#page_87">87</a>,
+  <a href="#page_88">88</a>; <i>Davisii</i>,
+  <a href="#page_88">88</a>; <i>ferruginea</i>,
+  <a href="#page_88">88</a>.<br/>
+<i>Liriodendron</i>, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>; <i>Meeki</i>,
+  <a href="#page_263">263</a>.<br/>
+<i>Lithostrotion</i>, <a href="#page_173">173</a>;
+  <i>irregulare</i>, <a href="#page_174">174</a>.<br/>
+<i>Lituites</i>, <a href="#page_130">130</a>.<br/>
+Lizards (see <i>Lacertilia</i>).<br/>
+Llama, <a href="#page_354">354</a>.<br/>
+Llanberis Slates, <a href="#page_79">79</a>.<br/>
+Llandeilo rocks, <a href="#page_92">92</a>,
+  <a href="#page_94">94</a>, <a href="#page_96">96</a>.<br/>
+Llandovery rocks, <a href="#page_93">93</a>; Lower,
+  <a href="#page_93">93</a>; Upper,
+  <a href="#page_115">115</a>.<br/>
+Lobsters, <a href="#page_180">180</a>,
+  <a href="#page_210">210</a>, <a href="#page_233">233</a>,
+  <a href="#page_267">267</a>.<br/>
+Loess, <a href="#page_339">339</a>.<br/>
+London Clay, <a href="#page_287">287</a>,
+  <a href="#page_288">288</a>.<br/>
+Longmynd rocks, <a href="#page_77">77-80</a>,
+  <a href="#page_83">83</a>.<br/>
+<i>Lonsdaleia</i>, <a href="#page_173">173</a>.<br/>
+<i>Lophiodon</i>, <a href="#page_316">316</a>.<br/>
+<i>Lophophyllum</i>, <a href="#page_173">173</a>.<br/>
+Lower Cambrian, <a href="#page_77">77-79</a>; Chalk,
+  <a href="#page_259">259</a>; Cretaceous,
+  <a href="#page_257">257</a>, <a href="#page_258">258</a>;
+  Devonian, <a href="#page_134">134</a>; Eocene,
+  <a href="#page_287">287</a>, <a href="#page_288">288</a>;
+  Greensand, <a href="#page_257">257</a>,
+  <a href="#page_258">258</a>; Helderberg,
+  <a href="#page_117">117</a>, <a href="#page_118">118</a>;
+  Laurentian rocks, <a href="#page_66">66</a>; Ludlow rock,
+  <a href="#page_116">116</a>; Miocene,
+  <a href="#page_305">305</a>; Old Red Sandstone,
+  <a href="#page_134">134</a>; Oolites,
+  <a href="#page_227">229</a>; Silurian period,
+  <a href="#page_90">90-114</a>; rocks of, in Britain,
+  <a href="#page_92">92-94</a>; in North America,
+  <a href="#page_94">94-96</a>; life of,
+  <a href="#page_97">97-114</a>.<br/>
+<i>Loxonema</i>, <a href="#page_186">186</a>,
+  <a href="#page_199">199</a>, <a href="#page_213">213</a>.<br/>
+Ludlow rock, <a href="#page_116">116</a>,
+  <a href="#page_117">117</a>.<br/>
+<i>Lycopodiaceœ</i>, <a href="#page_118">118</a>,
+  <a href="#page_136">136</a>, <a href="#page_167">167</a>.<br/>
+Lynton Group, <a href="#page_134">134</a>.<br/>
+<i>Lyrodesma</i>, <a href="#page_111">111</a>.
+</p>
+
+<p class="index">
+Macaques, <a href="#page_323">323</a>,
+  <a href="#page_331">331</a>.<br/>
+<i>Machœracanthus major</i>,
+  <a href="#page_151">151</a>, <a href="#page_155">155</a>.<br/>
+<i>Machairodus</i>, <a href="#page_221">221</a>,
+  <a href="#page_249">249</a>, <a href="#page_322">322</a>,
+  <a href="#page_331">331</a>, <a href="#page_360">360</a>;
+  <i>cultridens</i>, <a href="#page_331">331</a>.<br/>
+<i>Maclurea</i>, <a href="#page_111">111</a>; <i>crenulata</i>,
+  <a href="#page_112">112</a>.<br/>
+<i>Macrocheilus</i>, <a href="#page_186">186</a>,
+  <a href="#page_199">199</a>, <a href="#page_213">213</a>.<br/>
+<i>Macropetalichthys</i>, <a href="#page_152">152</a>;
+  <i>Sullivanti</i>, <a href="#page_151">151</a>.<br/>
+<i>Macrotherium giganteum</i>, <a href="#page_315">315</a>.<br/>
+<i>Macrurous Crustaceans</i>, <a href="#page_180">180</a>.<br/>
+<i>Mactra</i>, <a href="#page_292">292</a>.<br/>
+Maestricht Chalk, <a href="#page_259">259</a>,
+  <a href="#page_279">279</a>, <a href="#page_286">286</a>.<br/>
+Magnesian Limestone, <a href="#page_27">27</a>; nature and
+  structure of, <a href="#page_28">28</a>; of the Permian
+  series, <a href="#page_194">194</a>, <a href="#page_196">196</a>.<br/>
+Magnolia, <a href="#page_262">262</a>, <a href="#page_290">290</a>,
+  <a href="#page_310">310</a>.<br/>
+<i>Mammalia</i>, of the Trias, <a href="#page_223">223</a>,
+  <a href="#page_224">224</a>; of the Jurassic,
+  <a href="#page_253">253</a>, <a href="#page_254">254</a>;
+  of the Eocene, <a href="#page_299">299-305</a>; of the Miocene,
+  <a href="#page_313">313-323</a>; of the Pliocene,
+  <a href="#page_327">327-331</a>; of the Post-Pliocene,
+  <a href="#page_348">348-362</a>.<br/>
+Mammoth, <a href="#page_339">339</a>, <a href="#page_341">341</a>,
+  <a href="#page_344">344</a>, <a href="#page_357">357-359</a>.<br/>
+Man, remains of, in Post-Pliocene deposits,
+  <a href="#page_341">341</a>, <a href="#page_344">344</a>.<br/>
+Manatee, <a href="#page_299">299</a>.<br/>
+<i>Mantellia</i>, <a href="#page_230">230</a>;
+  <i>megalophylla</i>, <a href="#page_230">230</a>.<br/>
+Maple, <a href="#page_290">290</a>, <a href="#page_308">308</a>,
+  <a href="#page_310">310</a>.<br/>
+Marble, <a href="#page_28">28</a>; encrinital,
+  <a href="#page_24">24</a>; statuary, <a href="#page_27">27</a>.<br/>
+Marcellus Shales, <a href="#page_135">135</a>.<br/>
+<i>Mariacrinus</i>, <a href="#page_122">122</a>.<br/>
+Marmots, <a href="#page_322">322</a>.<br/>
+Marsupials, <a href="#page_299">299</a>; of the Trias,
+  <a href="#page_223">223</a>; of the Jurassic,
+  <a href="#page_253">253</a>, <a href="#page_254">254</a>;
+  of the Eocene, <a href="#page_299">299</a>; of the Miocene,
+  <a href="#page_315">315</a>; of the Post-Pliocene,
+  <a href="#page_348">348</a>, <a href="#page_319">319</a>.<br/>
+<i>Marsupiocrinus</i>, <a href="#page_122">122</a>.<br/>
+<i>Marsupites</i>, <a href="#page_266">266</a>.<br/>
+<i>Mastodon</i>, <a href="#page_319">319</a>,
+  <a href="#page_321">321</a>, <a href="#page_322">322</a>;
+  <i>Americanus, angustidens</i>, <a href="#page_322">322</a>;
+  <i>Arvenensis</i>, <a href="#page_329">329</a>;
+  <i>longirostris</i>, <a href="#page_322">322</a>;
+  <i>Ohioticus</i>, <a href="#page_357">357</a>;
+  <i>Sivalensis</i>, <a href="#page_321">321</a>.<br/>
+Medina Sandstone, <a href="#page_116">116</a>.<br/>
+<i>Megalichthys</i>, <a href="#page_188">188</a>.<br/>
+<i>Megalodon</i>, <a href="#page_148">148</a>.<br/>
+<i>Megalomus</i>, <a href="#page_128">128</a>.<br/>
+<i>Megalonyx</i>, <a href="#page_351">351</a>.<br/>
+<i>Megalosaurus</i>, <a href="#page_249">249</a>,
+  <a href="#page_278">278</a>.<br/>
+<i>Megatherium</i>, <a href="#page_350">350</a>,
+  <a href="#page_351">351</a>; <i>Cuvieri</i>,
+  <a href="#page_350">350</a>.<br/>
+<i>Melania</i>, <a href="#page_294">294</a>.<br/>
+<i>Melonites</i>, <a href="#page_178">178</a>.<br/>
+Menevian Group, <a href="#page_77">77-79</a>.<br/>
+<i>Menobranchus</i>, <a href="#page_189">189</a>.<br/>
+<i>Meristella</i>, <a href="#page_127">127</a>;
+  <i>cylindrica</i>, <a href="#page_127">127</a>;
+  <i>intermedia</i>, <a href="#page_127">127</a>;
+  <i>naviformis</i>, <a href="#page_127">127</a>.<br/>
+<i>Mesopithecus</i>, <a href="#page_323">323</a>.<br/>
+Mesozoic Period, <a href="#page_44">44</a>.<br/>
+<i>Michelinia</i>, <a href="#page_142">142</a>.<br/>
+<i>Micraster</i>, <a href="#page_266">266</a>.<br/>
+<i>Microlestes</i>, <a href="#page_224">224</a>;
+  <i>antiquus</i>, <a href="#page_223">223</a>.<br/>
+<a name="page_403"><span class="page">Page 403</span></a>
+Middle Devonian, <a href="#page_134">134</a>; Eocene,
+  <a href="#page_287">287</a>, <a href="#page_288">288</a>,
+  <a href="#page_289">289</a>; Oolites,
+  <a href="#page_227">227</a>; Silurian,
+  <a href="#page_91">91</a>.<br/>
+Miliolite Limestone, <a href="#page_290">290</a>.<br/>
+<i>Millepora</i>, <a href="#page_230">230</a>.<br/>
+Millstone Grit, <a href="#page_159">159</a>,
+  <a href="#page_161">161</a>.<br/>
+Miocene period, <a href="#page_305">305</a>; rocks of,
+  in Britain, <a href="#page_305">305</a>,
+  <a href="#page_306">306</a>; in France,
+  <a href="#page_306">306</a>; in Belgium,
+  <a href="#page_307">307</a>; in Switzerland,
+  <a href="#page_306">306</a>; in Austria,
+  <a href="#page_307">307</a>; in Germany,
+  <a href="#page_307">307</a>; in Italy,
+  <a href="#page_307">307</a>; in India,
+  <a href="#page_307">307</a>; in North America,
+  <a href="#page_307">307</a>; life of,
+  <a href="#page_308">308-323</a>.<br/>
+Mitre-shells, <a href="#page_371">371</a>,
+  <a href="#page_293">293</a>.<br/>
+<i>Mitra</i>, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>.<br/>
+Moas of New Zealand, <a href="#page_346">346-348</a>.<br/>
+<i>Modiolopsis</i>, <a href="#page_111">111</a>;
+  <i>Solvensis</i>, <a href="#page_88">88</a>.<br/>
+Molasse, <a href="#page_306">306</a>.<br/>
+Mole, <a href="#page_322">322</a>,
+  <a href="#page_336">336</a>.<br/>
+Monkeys, <a href="#page_305">305</a>,
+  <a href="#page_331">331</a>.<br/>
+Monocotyledonous plant, <a href="#page_262">262</a>.<br/>
+<i>Monograptus</i>, <a href="#page_100">100</a>,
+  <a href="#page_119">119</a>; <i>priodon</i>,
+  <a href="#page_119">119</a>.<br/>
+<i>Monotis</i>, <a href="#page_211">211</a>.<br/>
+Monte Bolca, fishes of, <a href="#page_295">295</a>.<br/>
+<i>Montlivaltia</i>, <a href="#page_209">209</a>.<br/>
+Mosasauroids, <a href="#page_279">279</a>,
+  <a href="#page_280">280</a>.<br/>
+<i>Mosasaurus</i>, <a href="#page_279">279</a>;
+  <i>Camperi</i>, <a href="#page_279">279</a>;
+  <i>princeps</i>, <a href="#page_279">279</a>.<br/>
+Mountain Limestone, <a href="#page_158">158</a>,
+  <a href="#page_161">161</a>.<br/>
+Mud-fishes, <a href="#page_153">153</a>,
+  <a href="#page_215">215</a>.<br/>
+Mud-turtles, <a href="#page_280">280</a>.<br/>
+Mull, Miocene strata of, <a href="#page_306">306</a>.<br/>
+<i>Murchisonia</i>, <a href="#page_111">111</a>,
+  <a href="#page_129">129</a>, <a href="#page_199">199</a>,
+  <a href="#page_213">213</a>; <i>gracilis</i>,
+  <a href="#page_111">11</a>.<br/>
+<i>Murex</i>, <a href="#page_237">237</a>,
+  <a href="#page_293">293</a>.<br/>
+Muschelkalk, <a href="#page_203">203</a>,
+  <a href="#page_204">204</a>, <a href="#page_206">206</a>.<br/>
+Musk-deer, <a href="#page_317">317</a>.<br/>
+Musk-ox, <a href="#page_344">344</a>,
+  <a href="#page_345">345</a>, <a href="#page_356">356</a>.<br/>
+Musk-sheep, <a href="#page_356">356</a>.<br/>
+<i>Myliobatis Edwardsii</i>, <a href="#page_296">296</a>.<br/>
+<i>Mylodon</i>, <a href="#page_351">351</a>;
+  <i>robustus</i>, <a href="#page_352">352</a>.<br/>
+<i>Myophoria</i>, <a href="#page_211">211</a>;
+  <i>lineata</i>, <a href="#page_211">211</a>.<br/>
+<i>Myriapoda</i> of the Coal, <a href="#page_181">181</a>,
+  <a href="#page_182">182</a>.
+</p>
+
+<p class="index">
+<i>Nassa</i>, <a href="#page_293">293</a>.<br/>
+<i>Natatores</i>, <a href="#page_297">297</a>.<br/>
+<i>Natica</i>, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>.<br/>
+<i>Nautilus</i>, <a href="#page_112">112-114</a>,
+  <a href="#page_130">130</a>, <a href="#page_149">149</a>,
+  <a href="#page_186">186</a>, <a href="#page_199">199</a>,
+  <a href="#page_237">237</a>, <a href="#page_272">272</a>,
+  <a href="#page_294">294</a>; <i>Danicus</i>,
+  <a href="#page_272">272</a>; <i>pompilius</i>,
+  <a href="#page_237">237</a>.<br/>
+Neanderthal skull, <a href="#page_364">364</a>.<br/>
+Neocomian series, <a href="#page_257">257</a>,
+  <a href="#page_260">260</a>.<br/>
+<i>Neolimulus</i>, <a href="#page_125">125</a>.<br/>
+<i>Nerinœa</i>, <a href="#page_237">237</a>,
+  <a href="#page_271">271</a>; <i>Goodhallii</i>,
+  <a href="#page_237">237</a>.<br/>
+<i>Nerita</i>, <a href="#page_393">393</a>.<br/>
+<i>Neuroptera</i>, <a href="#page_311">311</a>.<br/>
+<i>Neuropteris</i>, <a href="#page_136">136</a>.<br/>
+Newer Pliocene, <a href="#page_323">323</a>,
+  <a href="#page_324">324</a>.<br/>
+New Red Sandstone, <a href="#page_193">193</a>,
+  <a href="#page_203">203</a>.<br/>
+Newts, <a href="#page_189">189</a>, <a href="#page_200">200</a>,
+  <a href="#page_217">217</a>.<br/>
+Niagara Limestone, <a href="#page_117">117</a>.<br/>
+<i>Nipadites</i>, <a href="#page_290">290</a>;
+  <i>ellipticus</i>, <a href="#page_290">290</a>.<br/>
+<i>Nœggerathia</i>, <a href="#page_197">197</a>.<br/>
+Norwich Crag, <a href="#page_324">324</a>.<br/>
+<i>Nothosaurus</i>, <a href="#page_219">219</a>;
+  <i>mirabilis</i>, <a href="#page_219">219</a>.<br/>
+<i>Notidanus</i>, <a href="#page_241">241</a>.<br/>
+<i>Numenius gypsorum</i>, <a href="#page_297">297</a>.<br/>
+<i>Nummulina</i>, <a href="#page_172">172</a>,
+  <a href="#page_290">290</a>; <i>lœvigata</i>,
+  <a href="#page_290">290</a>; <i>pristina</i>,
+  <a href="#page_172">172</a>.<br/>
+<i>Nummulitic Limestone</i>, <a href="#page_24">24</a>,
+  <a href="#page_287">287</a>, <a href="#page_291">291</a>.
+</p>
+
+<p class="index">
+Oak, <a href="#page_262">262</a>, <a href="#page_310">310</a>.<br/>
+<i>Obolella</i>, <a href="#page_87">87</a>; <i>sagittalis</i>,
+  <a href="#page_88">88</a>.<br/>
+Odd-toed Ungulates, <a href="#page_300">300</a>,
+  <a href="#page_315">315</a>, <a href="#page_327">327</a>,
+  <a href="#page_353">353</a>.<br/>
+<i>Odontaspis</i>, <a href="#page_275">275</a>.<br/>
+<i>Odontopteris</i>, <a href="#page_165">165</a>;
+  <i>Schlotheimi</i>, <a href="#page_164">164</a>.<br/>
+<i>Odontopteryx</i>, <a href="#page_297">297</a>;
+  <i>toliapicus</i>, <a href="#page_297">297</a>,
+  <a href="#page_298">298</a>.<br/>
+<i>Odontornithes</i>, <a href="#page_282">282</a>.<br/>
+<i>Ogygia</i>, <a href="#page_108">108</a>; <i>Buchii</i>,
+  <a href="#page_107">107</a>.<br/>
+Older Pliocene, <a href="#page_323">323</a>,
+  <a href="#page_324">324</a>.<br/>
+<i>Oldhamia</i>, <a href="#page_81">81</a>; <i>antiqua</i>,
+  <a href="#page_82">82</a>; slates of Ireland,
+  <a href="#page_79">79</a>, <a href="#page_80">80</a>.<br/>
+Old Red Sandstone, <a href="#page_133">133</a>; origin of name,
+  <a href="#page_133">133</a>; of Scotland,
+  <a href="#page_134">134</a>; relations of, to Devonian,
+  <a href="#page_133">133</a>, <a href="#page_134">134</a>,
+  <a href="#page_155">155</a>.<br/>
+<i>Olenus</i>, <a href="#page_108">108</a>; <i>micrurus</i>,
+  <a href="#page_88">88</a>.<br/>
+Oligocene, <a href="#page_305">305</a>.<br/>
+<i>Oligoporus</i>, <a href="#page_178">178</a>.<br/>
+Olive-shells, <a href="#page_293">293</a>.<br/>
+<i>Omphyma</i>, <a href="#page_119">119</a>.<br/>
+<i>Onchus</i>, <a href="#page_130">130</a>;
+  <i>tenuistriatus</i>, <a href="#page_131">131</a>.<br/>
+Oneida Conglomerate, <a href="#page_116">116</a>.<br/>
+<i>Onychodus</i>, <a href="#page_153">153</a>;
+  <i>sigmoides</i>, <a href="#page_151">151</a>.<br/>
+Oolitic limestone, structure of, <a href="#page_28">28</a>;
+  mode of formation of, <a href="#page_30">30</a>.<br/>
+Oolitic rocks (<i>see</i> Jurassic).<br/>
+Ooze, Atlantic, <a href="#page_22">22</a>,
+  <a href="#page_33">33</a>.<br/>
+<i>Ophidia</i>, <a href="#page_251">251</a>; of the Eocene,
+  <a href="#page_296">296</a>.<br/>
+<i>Ophiuroidea</i>, of the Lower Silurian,
+  <a href="#page_105">105</a>; of the Upper Silurian,
+  <a href="#page_120">120</a>; of the Carboniferous,
+  <a href="#page_177">177</a>; of the Trias,
+  <a href="#page_210">210</a>; of the Jurassic,
+  <a href="#page_233">233</a>.<br/>
+Opossum, <a href="#page_299">299</a>,
+  <a href="#page_315">315</a>.<br/>
+<i>Orbitoides</i>, <a href="#page_291">291</a>.<br/>
+Oriskany Sandstone, <a href="#page_135">135</a>.<br/>
+<i>Ormoxylon</i>, <a href="#page_138">138</a>.<br/>
+<i>Orohippus</i>, <a href="#page_302">302</a>.<br/>
+<i>Orthis</i>, <a href="#page_38">38</a>,
+  <a href="#page_109">109</a>, <a href="#page_125">125</a>,
+  <a href="#page_147">147</a>, <a href="#page_184">184</a>,
+  <a href="#page_199">199</a>; <i>biforata</i>,
+  <a href="#page_109">109</a>; <i>Davidsoni</i>,
+  <a href="#page_127">127</a>; <i>elegantula</i>,
+  <a href="#page_127">127</a>; <i>flabellulum</i>,
+  <a href="#page_109">109</a>; <i>Hicksii</i>,
+  <a href="#page_38">38</a>; <i>lenticularis</i>,
+  <a href="#page_38">38</a>; <i>plicatella</i>,
+  <a href="#page_110">110</a>; <i>resupinata</i>,
+  <a href="#page_185">185</a>; <i>subquadrala</i>,
+  <a href="#page_109">109</a>; <i>testudinaria</i>,
+  <a href="#page_110">110</a>.<br/>
+<i>Orthoceras</i>, <a href="#page_89">89</a>,
+  <a href="#page_112">112</a>, <a href="#page_113">113</a>,
+  <a href="#page_130">130</a>, <a href="#page_149">149</a>,
+  <a href="#page_186">186</a>, <a href="#page_213">213</a>;
+  <i>crebriseptum</i>, <a href="#page_113">113</a>.<br/>
+<i>Orthonota</i>, <a href="#page_111">111</a>.<br/>
+<i>Orthoptera</i>, <a href="#page_182">182</a>,
+  <a href="#page_311">311</a>.<br/>
+<i>Osmeroides</i>, <a href="#page_276">276</a>;
+  <i>Mantelli</i>, <a href="#page_276">276</a>.<br/>
+<i>Osmerus</i>, <a href="#page_276">276</a>.<br/>
+<i>Ostealepis</i>, <a href="#page_153">153</a>.<br/>
+<i>Ostracode</i> Crustaceans of the Cambrian,
+  <a href="#page_83">83</a>; of the Lower Silurian,
+  <a href="#page_107">107</a>; of the Upper Silurian,
+  <a href="#page_123">123</a>; of the Devonian,
+  <a href="#page_145">145</a>; of the Carboniferous,
+  <a href="#page_179">179</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_210">210</a>; of the Jurassic,
+  <a href="#page_233">233</a>; of the Cretaceous,
+  <a href="#page_267">267</a>.<br/>
+<i>Ostrea acuminata</i>, <a href="#page_235">235</a>;
+  <i>Couloni</i>, <a href="#page_269">269</a>;
+  <i>deltoidea</i>, <a href="#page_235">235</a>;
+  <i>distorta</i>, <a href="#page_235">235</a>;
+  <i>expansa, gregarea</i>, <a href="#page_235">235</a>;
+  <i>Marshii</i>, <a href="#page_235">235</a>,
+  <a href="#page_236">236</a>.<br/>
+<i>Otodus</i>, <a href="#page_295">295</a>;
+  <i>obtiquus</i>, <a href="#page_296">296</a>.<br/>
+<i>Otozamites</i>, <a href="#page_230">230</a>.<br/>
+<i>Otozoum</i>, <a href="#page_206">206</a>.<br/>
+<i>Oudenodon</i>, <a href="#page_220">220</a>;
+  <i>Bainii</i>, <a href="#page_221">221</a>.<br/>
+<i>Ovibos moschatus</i>, <a href="#page_356">356</a>.<br/>
+Oxford Clay, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+<i>Oxyrhina</i>, <a href="#page_312">312</a>;
+  <i>xiphodon</i>, <a href="#page_313">313</a>.<br/>
+Oysters, <a href="#page_235">235</a>,
+  <a href="#page_236">236</a>, <a href="#page_269">269</a>.
+</p>
+
+<p class="index">
+<i>Pachyphyllum</i>, <a href="#page_173">173</a>.<br/>
+<i>Palœarca</i>, <a href="#page_111">111</a>.<br/>
+<i>Palœaster</i>, <a href="#page_120">120</a>;
+  <i>Ruthveni</i>, <a href="#page_121">121</a>.<br/>
+<i>Palasterina</i>, <a href="#page_120">120</a>;
+  <i>primœva</i>, <a href="#page_121">121</a>.<br/>
+<i>Palœchinus</i>, <a href="#page_120">120</a>,
+  <a href="#page_178">178</a>; <i>ellipticus</i>,
+  <a href="#page_177">177</a>.<br/>
+<i>Palœocaris</i>, <a href="#page_180">180</a>;
+  <i>typus</i>, <a href="#page_180">180</a>.<br/>
+<i>Palœocoma</i>, <a href="#page_120">120</a>;
+  <i>Colvini</i>, <a href="#page_121">121</a>.<br/>
+<i>Palœocoryne</i>, <a href="#page_172">172</a>.<br/>
+Palæolithic man, remains of,
+  <a href="#page_363">363-365</a>.<br/>
+<i>Palœomanon</i>, <a href="#page_118">118</a>.<br/>
+<i>Palœoniscus</i>, <a href="#page_188">188</a>,
+  <a href="#page_200">200</a>.<br/>
+<a name="page_404"><span class="page">Page 404</span></a>
+<i>Palœontina Oolitica</i>, <a href="#page_233">233</a>.<br/>
+Palæontological evidence as to Evolution,
+  <a href="#page_60">60</a>, <a href="#page_372">372-374</a>.<br/>
+Palæontological record, imperfection of the,
+  <a href="#page_50">50</a>, <a href="#page_51">51</a>.<br/>
+Palæontology, definition of, <a href="#page_10">10</a>.<br/>
+<i>Palœonyctis</i>, <a href="#page_304">304</a>.<br/>
+<i>Palœophis</i>, <a href="#page_296">296</a>;
+  <i>toliapictus</i>, <a href="#page_296">296</a>;
+  <i>typhœus</i>, <a href="#page_296">296</a>.<br/>
+<i>Palœoreas</i>, <a href="#page_318">318</a>.<br/>
+<i>Palœosaurus</i>, <a href="#page_200">200</a>,
+  <a href="#page_218">218</a>, <a href="#page_219">219</a>;
+  <i>platyodon</i>, <a href="#page_219">219</a>.<br/>
+<i>Palœosiren Beinerti</i>, <a href="#page_200">200</a>.<br/>
+<i>Palœotherium</i>, <a href="#page_300">300</a>;
+  <i>magnum</i>, <a href="#page_301">301</a>.<br/>
+<i>Palœoxylon</i>, <a href="#page_170">170</a>.<br/>
+Palæozoic period, <a href="#page_44">44</a>.<br/>
+Palms, <a href="#page_230">230</a>, <a href="#page_263">263</a>,
+  <a href="#page_290">290</a>, <a href="#page_308">308</a>,
+  <a href="#page_309">309</a>.<br/>
+<i>Paludina</i>, <a href="#page_257">257</a>,
+  <a href="#page_294">294</a>.<br/>
+<i>Pandaneœ</i>, <a href="#page_230">230</a>.<br/>
+<i>Pandanus</i>, <a href="#page_262">262</a>.<br/>
+<i>Paradoxides</i>, <a href="#page_86">86</a>,
+  <a href="#page_87">87</a>, <a href="#page_108">108</a>;
+  <i>Bohemicus</i>, <a href="#page_85">85</a>.<br/>
+<i>Parasmilia</i>, <a href="#page_266">266</a>.<br/>
+<i>Parkeria</i>, <a href="#page_264">264</a>.<br/>
+Pear Encrinite, <a href="#page_231">231</a>.<br/>
+Pearly Nautilus, <a href="#page_58">58</a>,
+  <a href="#page_111">111</a>, <a href="#page_112">112</a>,
+  <a href="#page_237">237</a>.<br/>
+Peccaries, <a href="#page_317">317</a>.<br/>
+<i>Pecopteris</i>, <a href="#page_136">136</a>,
+  <a href="#page_165">165</a>, <a href="#page_196">196</a>.<br/>
+<i>Pecten Grœnlandicus</i>, <a href="#page_338">338</a>;
+  <i>Islandicus</i>, <a href="#page_338">338</a>;
+  <i>Valoniensis</i>, <a href="#page_211">211</a>,
+  <a href="#page_212">212</a>, <a href="#page_204">204</a>.<br/>
+Penarth Beds, <a href="#page_204">204</a>.<br/>
+<i>Pennatulidœ</i>, <a href="#page_292">292</a>.<br/>
+<i>Pentacrinus</i>, <a href="#page_231">231</a>;
+  <i>caput-medusœ</i>, <a href="#page_231">231</a>;
+  <i>fasciculosus</i>, <a href="#page_232">232</a>.<br/>
+<i>Pentamerus</i>, <a href="#page_125">125</a>,
+  <a href="#page_126">126</a>; <i>galeatus</i>,
+  <a href="#page_126">126</a>; <i>Knightii</i>,
+  <a href="#page_128">128</a>.<br/>
+<i>Pentremites</i> (<i>see</i> Blastoidea).<br/>
+<i>Pentremites conoideus</i>, <a href="#page_176">176</a>;
+  <i>pyriformis</i>, <a href="#page_176">176</a>.<br/>
+Perching Birds, <a href="#page_297">297</a>.<br/>
+<i>Percidœ</i>, <a href="#page_276">276</a>.<br/>
+<i>Periechocrinus</i>, <a href="#page_122">122</a>.<br/>
+<i>Perissodactyle Ungulates</i>, <a href="#page_300">300</a>,
+  <a href="#page_315">315</a>, <a href="#page_327">327</a>.<br/>
+Permian period, <a href="#page_192">192-202</a>; rocks of, in
+  Britain, <a href="#page_194">194</a>; in North America,
+  <a href="#page_194">194</a>; life of,
+  <a href="#page_195">195-302</a>.<br/>
+Persistent types of life, <a href="#page_58">58</a>,
+  <a href="#page_371">371</a>.<br/>
+<i>Petalodus</i>, <a href="#page_188">188</a>.<br/>
+<i>Petraster</i>, <a href="#page_120">120</a>.<br/>
+Petroleum, origin of, <a href="#page_36">36</a>.<br/>
+Pezophaps, <a href="#page_348">348</a>.<br/>
+<i>Phacops</i>, <a href="#page_108">108</a>,
+  <a href="#page_123">123</a>, <a href="#page_145">145</a>;
+  <i>Downingiœ</i>, <a href="#page_124">124</a>;
+  <i>granulatus</i>, <a href="#page_144">144</a>;
+  <i>lœvis</i>, <a href="#page_144">144</a>;
+  <i>latifrons</i>, <a href="#page_144">144</a>,
+  <a href="#page_145">145</a>; <i>longicaudatus</i>,
+  <a href="#page_124">124</a>; <i>rana</i>,
+  <a href="#page_145">145</a>.<br/>
+<i>Phœnopora ensiformis</i>, <a href="#page_126">126</a>.<br/>
+Phalangers, <a href="#page_348">348</a>.<br/>
+Phanerogams, <a href="#page_164">164</a>.<br/>
+<i>Phaneropleuron</i>, <a href="#page_153">153</a>.<br/>
+<i>Phascolotherium</i>, <a href="#page_253">253</a>,
+  <a href="#page_254">254</a>.<br/>
+<i>Pheronema</i>, <a href="#page_264">164</a>.<br/>
+<i>Phillipsastrœa</i>, <a href="#page_142">142</a>.<br/>
+<i>Phillipsia</i>, <a href="#page_179">179</a>;
+  <i>seminifera</i>, <a href="#page_180">180</a>.<br/>
+<i>Pholadomya</i>, <a href="#page_235">235</a>.<br/>
+<i>Phormosoma</i>, <a href="#page_178">178</a>.<br/>
+<i>Phorus</i>, <a href="#page_271">271</a>.<br/>
+Phosphate of lime, concretions of, <a href="#page_30">30</a>;
+  disseminated in rocks, <a href="#page_30">30</a>; origin of,
+  <a href="#page_31">31</a>.<br/>
+<i>Phyllograptus</i>, <a href="#page_102">102</a>;
+  <i>typus</i>, <a href="#page_102">102</a>.<br/>
+<i>Phyllopoda</i>, of the Cambrian, <a href="#page_83">83</a>;
+  of the Lower Silurian, <a href="#page_108">108</a>; of the
+  Upper Silurian, <a href="#page_123">123</a>; of the Devonian,
+  <a href="#page_145">145</a>; of the Carboniferous,
+  <a href="#page_179">179</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_210">210</a>.<br/>
+<i>Phyllopora</i>, <a href="#page_210">210</a>.<br/>
+<i>Physa</i>, <a href="#page_294">294</a>;
+  <i>columnaris</i>, <a href="#page_294">294</a>.<br/>
+Pigs, <a href="#page_302">302</a>, <a href="#page_317">317</a>,
+  <a href="#page_329">329</a>, <a href="#page_354">354</a>.<br/>
+Pilton Group, <a href="#page_135">135</a>.<br/>
+<i>Pinites</i>, <a href="#page_170">170</a>.<br/>
+<i>Pisces</i> (<i>see</i> Fishes).<br/>
+<i>Pisolite</i>, <a href="#page_29">29</a>.<br/>
+Pisolitic Limestone of France, <a href="#page_259">259</a>,
+  <a href="#page_286">286</a>.<br/>
+<i>Placodus</i>, <a href="#page_220">220</a>; <i>gigas</i>,
+  <a href="#page_220">220</a>.<br/>
+Placoid Fishes, <a href="#page_150">150</a>; of the Upper
+  Silurian, <a href="#page_130">130</a>, <a href="#page_131">131</a>;
+  of the Devonian, <a href="#page_153">153-155</a>; of the
+  Carboniferous, <a href="#page_188">188</a>; of the Permian,
+  <a href="#page_199">199</a>; of the Trias,
+  <a href="#page_214">214</a>; of the Jurassic,
+  <a href="#page_241">241</a>; of the Cretaceous,
+  <a href="#page_275">275</a>; of the Eocene,
+  <a href="#page_295">295</a>; of the Miocene,
+  <a href="#page_312">312</a>.<br/>
+<i>Plagiaulax</i>, <a href="#page_254">254</a>.<br/>
+<i>Planolites</i>, <a href="#page_122">122</a>;
+  <i>vulgaris</i>, <a href="#page_123">123</a>.<br/>
+<i>Planorbis</i>, <a href="#page_294">294</a>.<br/>
+Plants, of the Cambrian, <a href="#page_80">80</a>,
+  <a href="#page_81">81</a>; of the Lower Silurian,
+  <a href="#page_97">97</a>, <a href="#page_98">98</a>; of the
+  Upper Silurian, <a href="#page_118">118</a>; of the Devonian,
+  <a href="#page_136">136-139</a>; of the Carboniferous,
+  <a href="#page_163">163-170</a>; of the Permian,
+  <a href="#page_196">196</a>; of the Trias,
+  <a href="#page_207">207</a>, <a href="#page_208">208</a>;
+  of the Jurassic, <a href="#page_229">229</a>,
+  <a href="#page_230">230</a>; of the Cretaceous,
+  <a href="#page_261">261-263</a>; of the Eocene,
+  <a href="#page_289">289</a>, <a href="#page_290">290</a>;
+  of the Miocene, <a href="#page_308">308-311</a>.<br/>
+<i>Plasmopora</i>, <a href="#page_119">119</a>.<br/>
+<i>Platanus</i>, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>; <i>aceroides</i>,
+  <a href="#page_309">309</a>.<br/>
+<i>Platephemera antiqua</i>, <a href="#page_145">145</a>.<br/>
+<i>Platyceras</i>, <a href="#page_128">128</a>,
+  <a href="#page_148">148</a>; <i>dumosum</i>,
+  <a href="#page_148">148</a>; <i>multisinuatum</i>,
+  <a href="#page_129">129</a>; <i>ventricosum</i>,
+  <a href="#page_129">129</a>.<br/>
+<i>Platycrinus</i>, <a href="#page_122">122</a>,
+  <a href="#page_175">175</a>; <i>tricontadactylus</i>,
+  <a href="#page_175">175</a>.<br/>
+<i>Platyostoma</i>, <a href="#page_129">129</a>;
+  <i>Niagarense</i>, <a href="#page_129">129</a>.<br/>
+Platyrhine Monkeys, <a href="#page_362">362</a>.<br/>
+<i>Platyschisma helicites</i>, <a href="#page_129">129</a>.<br/>
+<i>Platysomus</i>, <a href="#page_200">200</a>;
+  <i>gibbosus</i>, <a href="#page_199">199</a>.<br/>
+<i>Platystoma</i>, <a href="#page_213">213</a>.<br/>
+Pleistocene period; climate of.<br/>
+<i>Plesiosaurus</i>, <a href="#page_334">334</a>;
+  <i>dolichodeirus</i>, <a href="#page_244">244</a>.<br/>
+<i>Pleurocystites squamosus</i>, <a href="#page_106">106</a>.<br/>
+<i>Pleurotoma</i>, <a href="#page_293">293</a>.<br/>
+<i>Pleurotomaria</i>, <a href="#page_111">111</a>,
+  <a href="#page_129">129</a>, <a href="#page_186">186</a>,
+  <a href="#page_199">199</a>, <a href="#page_236">236</a>,
+  <a href="#page_271">271</a>.<br/>
+<i>Plicatula</i>, <a href="#page_213">213</a>.<br/>
+Pliocene period, <a href="#page_323">323</a>; rocks of, in
+  Britain, <a href="#page_324">324</a>; in Belgium,
+  <a href="#page_325">325</a>; in Italy,
+  <a href="#page_325">325</a>; in North America,
+  <a href="#page_326">326</a>; life of,
+  <a href="#page_326">326-331</a>.<br/>
+<i>Pliopithecus</i>, <a href="#page_322">322</a>;
+  <i>antiquus</i>, <a href="#page_323">323</a>.<br/>
+<i>Pliosaurus</i>, <a href="#page_245">245</a>.<br/>
+<i>Podocarya</i>, <a href="#page_230">230</a>.<br/>
+<i>Podozamites</i>, <a href="#page_208">208</a>;
+  <i>lanceolatus</i>, <a href="#page_209">209</a>.<br/>
+Polir-schiefer, <a href="#page_33">33</a>.<br/>
+<i>Polycystina</i>, <a href="#page_32">32</a>; of
+  Barbadoes-earth, <a href="#page_33">33</a>.<br/>
+<i>Polypora</i>, <a href="#page_145">145</a>,
+  <a href="#page_184">184</a>; <i>dendroides</i>,
+  <a href="#page_183">183</a>.<br/>
+<i>Polypterus</i>, <a href="#page_153">153</a>,
+  <a href="#page_188">188</a>.<br/>
+<i>Polystomella</i>, <a href="#page_311">311</a>.<br/>
+<i>Polytremacis</i>, <a href="#page_266">266</a>.<br/>
+<i>Polyzoa</i>, of the Cambrian, <a href="#page_81">81</a>,
+  <a href="#page_89">89</a>; of the Lower Silurian,
+  <a href="#page_108">108</a>; of the Upper Silurian,
+  <a href="#page_125">125</a>; of the Devonian,
+  <a href="#page_145">145</a>, <a href="#page_146">146</a>;
+  of the Carboniferous, <a href="#page_183">183</a>,
+  <a href="#page_184">184</a>; of the Permian,
+  <a href="#page_198">198</a>; of the Trias,
+  <a href="#page_210">210</a>; of the Cretaceous,
+  <a href="#page_267">267</a>; of the Miocene,
+  <a href="#page_312">312</a>.<br/>
+<i>Populus</i>, <a href="#page_262">262</a>.<br/>
+<i>Porcellia</i>, <a href="#page_186">186</a>.<br/>
+Porcupines, <a href="#page_322">322</a>.<br/>
+Portage Group, <a href="#page_135">135</a>.<br/>
+Port-Jackson Shark, <a href="#page_154">154</a>.<br/>
+Portland beds, <a href="#page_227">227</a>,
+  <a href="#page_229">229</a>.<br/>
+Post-Glacial deposits, <a href="#page_336">336</a>,
+  <a href="#page_338">338</a>.<br/>
+<a name="page_405"><span class="page">Page 405</span></a>
+Post-Pliocene period, <a href="#page_334">334</a>.<br/>
+Post-Tertiary period, <a href="#page_286">286</a>.<br/>
+<i>Poteriocrinus</i>, <a href="#page_175">175</a>.<br/>
+Potsdam Sandstone, <a href="#page_79">79</a>.<br/>
+Pre-Glacial deposits, <a href="#page_336">336</a>.<br/>
+<i>Prestwichia</i>, <a href="#page_179">179</a>;
+  <i>rotundata</i>, <a href="#page_179">179</a>.<br/>
+<i>Primitia</i>, <a href="#page_107">107</a>;
+  <i>strangulata</i>, <a href="#page_107">107</a>.<br/>
+Primordial Trilobites, <a href="#page_85">85</a>.<br/>
+Primordial zone, <a href="#page_79">79</a>.<br/>
+<i>Proboscidea</i>, of the Miocene,
+  <a href="#page_319">319</a>, <a href="#page_322">322</a>;
+  of the Pliocene, <a href="#page_329">329</a>,
+  <a href="#page_330">330</a>; of the Post-Pliocene,
+  <a href="#page_357">357-359</a>.<br/>
+<i>Producta</i>, <a href="#page_147">147</a>,
+  <a href="#page_184">184</a>, <a href="#page_198">198</a>;
+  <i>horrida</i>, <a href="#page_198">198</a>;
+  <i>longispina</i>, <a href="#page_185">185</a>;
+  <i>semireticulata</i>, <a href="#page_185">185</a>.<br/>
+<i>Productella</i>, <a href="#page_147">147</a>,
+  <a href="#page_184">184</a>.<br/>
+<i>Productidœ</i>, <a href="#page_147">147</a>,
+  <a href="#page_211">211</a>.<br/>
+<i>Pro&euml;tus</i>, <a href="#page_123">123</a>.<br/>
+Prong-buck, <a href="#page_318">318</a>.<br/>
+<i>Protaster</i>, <a href="#page_120">120</a>;
+  <i>Sedgwickii</i>, <a href="#page_121">121</a>.<br/>
+<i>Proteaceœ</i>, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>, <a href="#page_309">309</a>.<br/>
+<i>Proteus</i>, <a href="#page_189">189</a>.<br/>
+<i>Protichnites</i>, <a href="#page_87">87</a>.<br/>
+<i>Protocystites</i>, <a href="#page_82">82</a>.<br/>
+<i>Protornis Glarisiensis</i>, <a href="#page_279">279</a>.<br/>
+<i>Protorosaurus</i>, <a href="#page_201">201</a>,
+  <a href="#page_202">202</a>; <i>Speneri</i>,
+  <a href="#page_201">201</a>.<br/>
+<i>Protospongia</i>, <a href="#page_81">81</a>;
+  <i>fenestrata</i>, <a href="#page_88">88</a>.<br/>
+<i>Prototaxites</i>, <a href="#page_118">118</a>,
+  <a href="#page_138">138</a>; <i>Logani</i>,
+  <a href="#page_139">139</a>.<br/>
+<i>Psammobia</i>, <a href="#page_292">292</a>.<br/>
+<i>Psammodus</i>, <a href="#page_188">188</a>.<br/>
+<i>Psaronius</i>, <a href="#page_136">136</a>,
+  <a href="#page_164">164</a>.<br/>
+<i>Pseudocrinus bifasciatus</i>, <a href="#page_106">106</a>.<br/>
+<i>Psilophyton</i>, <a href="#page_118">118</a>,
+  <a href="#page_137">137</a>, <a href="#page_138">138</a>;
+  <i>princeps</i>, <a href="#page_138">138</a>.<br/>
+<i>Pteranodon</i>, <a href="#page_247">247</a>,
+  <a href="#page_277">277</a>; <i>longiceps</i>,
+  <a href="#page_277">277</a>.<br/>
+<i>Pteraspis</i>, <a href="#page_130">130</a>,
+  <a href="#page_152">152</a>; <i>Banksii</i>,
+  <a href="#page_130">130</a>.<br/>
+<i>Pterichthys</i>, <a href="#page_152">152</a>;
+  <i>cornutus</i>, <a href="#page_153">153</a>.<br/>
+<i>Pterinœa</i>, <a href="#page_128">128</a>;
+  <i>subfalcata</i>, <a href="#page_128">128</a>.<br/>
+<i>Pteroceras</i>, <a href="#page_237">237</a>,
+  <a href="#page_271">271</a>.<br/>
+<i>Pterodactylus</i>, <a href="#page_245">245</a>,
+  <a href="#page_277">277</a>; <i>crassirostris</i>,
+  <a href="#page_246">246</a>.<br/>
+<i>Pterophyllum</i>, <a href="#page_208">208</a>,
+  <a href="#page_230">230</a>; <i>Jœgeri</i>,
+  <a href="#page_209">209</a>.<br/>
+<i>Pteropoda</i>, of the Cambrian, <a href="#page_88">88</a>;
+  of the Lower Silurian, <a href="#page_111">111</a>; of the
+  Upper Silurian, <a href="#page_129">129</a>; of the Devonian,
+  <a href="#page_148">148</a>; of the Carboniferous,
+  <a href="#page_186">186</a>; of the Permian,
+  <a href="#page_199">199</a>; of the Jurassic,
+  <a href="#page_237">237</a>.<br/>
+<i>Pterosauria</i>, <a href="#page_245">245</a>; of the
+  Jurassic, <a href="#page_245">245-248</a>; of the
+  Cretaceous, <a href="#page_277">277</a>.<br/>
+<i>Pterygotus Anglicus</i>, <a href="#page_124">124</a>,
+  <a href="#page_125">125</a>.<br/>
+<i>Ptilodictya</i>, <a href="#page_108">108</a>,
+  <a href="#page_125">125</a>; <i>acuta</i>,
+  <a href="#page_109">109</a>; <i>falciformis</i>,
+  <a href="#page_109">109</a>; <i>raripora</i>,
+  <a href="#page_126">126</a>; <i>Schafferi</i>,
+  <a href="#page_109">109</a>.<br/>
+<i>Ptychoceras</i>, <a href="#page_273">273</a>;
+  <i>Emericianum</i>, <a href="#page_274">274</a>.<br/>
+<i>Ptychodus</i>, <a href="#page_275">275</a>.<br/>
+<i>Pupa vetusta</i>, <a href="#page_186">186</a>.<br/>
+Purbeck Beds, <a href="#page_228">228</a>; Mammals of,
+  <a href="#page_254">254</a>.<br/>
+<i>Puryuroidea</i>, <a href="#page_237">237</a>.<br/>
+<i>Pycnodus</i>, <a href="#page_275">275</a>.<br/>
+<i>Pyrula</i>, <a href="#page_293">293</a>.
+</p>
+
+<p class="index">
+<i>Quadrumana</i>, of the Eocene, <a href="#page_305">305</a>;
+  of the Miocene, <a href="#page_322">322</a>,
+  <a href="#page_323">323</a>; of the Pliocene,
+  <a href="#page_331">331</a>; of the Post-Pliocene,
+  <a href="#page_361">361</a>.<br/>
+Quadrupeds (<i>see</i> Mammalia).<br/>
+Quaternary period, <a href="#page_334">334</a>.<br/>
+Quebec Group, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+<i>Quercus</i>, <a href="#page_262">262</a>.
+</p>
+
+<p class="index">
+Rabbits, <a href="#page_322">322</a>.<br/>
+<i>Rana</i>, <a href="#page_313">313</a>.<br/>
+<i>Raptores</i>, <a href="#page_297">297</a>.<br/>
+<i>Rasores</i>, <a href="#page_297">297</a>.<br/>
+Recent period, <a href="#page_286">286</a>,
+  <a href="#page_334">334</a>.<br/>
+<i>Reptaculites</i>, <a href="#page_99">99</a>.<br/>
+Red clays, origin of, <a href="#page_35">35</a>.<br/>
+Red Coral, <a href="#page_311">311</a>.<br/>
+Red Crag, <a href="#page_324">324</a>.<br/>
+Red Deer, <a href="#page_336">336</a>,
+  <a href="#page_354">354</a>.<br/>
+Reindeer, <a href="#page_344">344</a>,
+  <a href="#page_345">345</a>, <a href="#page_354">354</a>,
+  <a href="#page_355">355</a>.<br/>
+<i>Remopleurides</i>, <a href="#page_188">188</a>.<br/>
+Reptiles, <a href="#page_200">200</a>; of the Permian,
+  <a href="#page_200">200-202</a>; of the Trias,
+  <a href="#page_217">217-221</a>; of the Jurassic,
+  <a href="#page_242">242-251</a>; of the Cretaceous,
+  <a href="#page_276">276-281</a>; of the Eocene,
+  <a href="#page_296">296</a>, <a href="#page_297">297</a>.<br/>
+<i>Retepora</i>, <a href="#page_108">108</a>,
+  <a href="#page_125">125</a>, <a href="#page_145">145</a>,
+  <a href="#page_184">184</a>, <a href="#page_198">198</a>,
+  <a href="#page_210">210</a>; <i>Ehrenbergi</i>,
+  <a href="#page_198">198</a>; <i>Phillipsi</i>,
+  <a href="#page_146">146</a>.<br/>
+<i>Retiolites</i>, <a href="#page_119">119</a>.<br/>
+<i>Retzia</i>, <a href="#page_127">127</a>.<br/>
+<i>Rhætic Beds</i>, <a href="#page_204">204-206</a>.<br/>
+<i>Rhamphorhynchus</i>, <a href="#page_247">247</a>;
+  <i>Bucklandi</i>, <a href="#page_248">248</a>.<br/>
+<i>Rhinoceridœ</i>, <a href="#page_315">315</a>.<br/>
+<i>Rhinoceros Etruscus</i>, <a href="#page_327">327</a>,
+  <a href="#page_328">328</a>, <a href="#page_336">336</a>,
+  <a href="#page_353">353</a>; <i>leptorhinus</i>,
+  <a href="#page_328">328</a>; <i>megarhinus</i>,
+  <a href="#page_327">327-329</a>, <a href="#page_336">336</a>,
+  <a href="#page_353">335</a>; <i>tichorhinus</i>,
+  <a href="#page_353">353</a>, <a href="#page_354">354</a>.<br/>
+<i>Rhinopora verrucosa</i>, <a href="#page_126">126</a>.<br/>
+<i>Rhizodus</i>, <a href="#page_188">188</a>.<br/>
+<i>Rhombus minimus</i>, <a href="#page_295">295</a>.<br/>
+Rhyncholites, <a href="#page_239">239</a>.<br/>
+<i>Rhynchonella</i>, <a href="#page_110">110</a>,
+  <a href="#page_127">127</a>, <a href="#page_147">147</a>,
+  <a href="#page_184">184</a>, <a href="#page_234">234</a>,
+  <a href="#page_268">268</a>, <a href="#page_292">292</a>;
+  <i>cuneata</i>, <a href="#page_127">127</a>; <i>neglecta</i>,
+  <a href="#page_127">127</a>; <i>pleurodon</i>,
+  <a href="#page_185">185</a>; <i>varians</i>,
+  <a href="#page_235">235</a>.<br/>
+<i>Rhynchosaurus</i>, <a href="#page_218">218</a>;
+  <i>articeps</i>, <a href="#page_218">218</a>.<br/>
+Rice-shells, <a href="#page_293">293</a>.<br/>
+Richmond Earth, <a href="#page_33">33</a>,
+  <a href="#page_307">307</a>.<br/>
+Ringed Worms (<i>see</i> Annelida).<br/>
+River-gravels, high-level and low-level,
+  <a href="#page_340">340</a>, <a href="#page_341">341</a>.<br/>
+<i>Robulina</i>, <a href="#page_311">311</a>.<br/>
+Rocks, definition of, <a href="#page_14">14</a>; divisions of,
+  <a href="#page_14">14</a>, <a href="#page_15">15</a>; igneous,
+  <a href="#page_14">14</a>; aqueous,
+  <a href="#page_15">15-18</a>; mechanically-formed,
+  <a href="#page_18">18-20</a>; chemically-formed,
+  <a href="#page_20">20</a>; organically-formed,
+  <a href="#page_20">20-37</a>; arenaceous,
+  <a href="#page_20">20</a>; argillaceous,
+  <a href="#page_20">20</a>; calcareous,
+  <a href="#page_20">20-32</a>; siliceous,
+  <a href="#page_20">20</a>, <a href="#page_32">32-34</a>.<br/>
+<i>Rodentia</i>, of the Eocene, <a href="#page_305">305</a>;
+  of the Miocene, <a href="#page_322">322</a>; of the
+  Post-Pliocene, <a href="#page_361">361</a>.<br/>
+Roebuck, <a href="#page_336">336</a>,
+  <a href="#page_354">354</a>.<br/>
+<i>Rostellaria</i>, <a href="#page_237">237</a>,
+  <a href="#page_293">293</a>.<br/>
+<i>Rotalia</i>, <a href="#page_22">22</a>,
+  <a href="#page_98">98</a>, <a href="#page_171">171</a>,
+  <a href="#page_264">264</a>; <i>Boueana</i>,
+  <a href="#page_264">264</a>.<br/>
+Rugose Corals, <a href="#page_104">104</a>; of the Lower
+  Silurian, <a href="#page_104">104</a>,
+  <a href="#page_105">105</a>; of the Upper Silurian,
+  <a href="#page_119">119</a>; of the Devonian,
+  <a href="#page_141">141</a>; of the Carboniferous,
+  <a href="#page_172">172-174</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Upper Greensand,
+  <a href="#page_266">266</a>.<br/>
+Rupelian Clay, <a href="#page_307">307</a>.
+</p>
+
+<p class="index">
+<i>Sabal major</i>, <a href="#page_309">309</a>.<br/>
+Sabre-toothed Tiger, <a href="#page_322">322</a>,
+  <a href="#page_331">331</a>.<br/>
+<i>Saccammina</i>, <a href="#page_172">172</a>.<br/>
+<i>Saccosoma</i>, <a href="#page_232">232</a>.<br/>
+Salamanders, <a href="#page_189">189</a>,
+  <a href="#page_313">313</a>.<br/>
+Salina Group, <a href="#page_117">117</a>.<br/>
+<i>Salix</i>, <a href="#page_262">262</a>; <i>Meeki</i>,
+  <a href="#page_263">263</a>.<br/>
+<i>Salmonidœ</i>, <a href="#page_276">276</a>.<br/>
+<i>Sao hirsuta</i>, <a href="#page_85">85</a>.<br/>
+<i>Sassafras cretacea</i>, <a href="#page_263">263</a>.<br/>
+<i>Sauropterygia</i>, <a href="#page_219">219</a>.<br/>
+<i>Scalaria</i>, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>; <i>Grœnlandica</i>,
+  <a href="#page_338">338</a>.<br/>
+<i>Scaphites</i>, <a href="#page_272">272</a>,
+  <a href="#page_273">273</a>; <i>œqualis</i>,
+  <a href="#page_274">274</a>.<br/>
+<i>Schizodus</i>, <a href="#page_198">198</a>,
+  <a href="#page_211">211</a>.<br/>
+Schoharie Grit, <a href="#page_135">135</a>,
+  <a href="#page_137">137</a>.<br/>
+<i>Scolecoderma</i>, <a href="#page_82">82</a>.<br/>
+<i>Scoliostoma</i>, <a href="#page_213">213</a>.<br/>
+<i>Scolithus</i>, <a href="#page_82">82</a>;
+  <i>Canadensis</i>, <a href="#page_83">83</a>.<br/>
+Scorpions of the Coal-measures,
+  <a href="#page_181">181</a>.<br/>
+Scorpion-shells, <a href="#page_271">271</a>.<br/>
+<a name="page_406"><span class="page">Page 406</span></a>
+Screw-pines, <a href="#page_230">230</a>.<br/>
+<i>Scutella</i>, <a href="#page_311">311</a>;
+  <i>subrotunda</i>, <a href="#page_312">312</a>.<br/>
+Sea-cows (<i>see</i> Sirenia).<br/>
+Sea-lilies (<i>see</i> Crinoidea).<br/>
+Sea-lizards (<i>see</i> Enaliosaurians).<br/>
+Seals, <a href="#page_322">322</a>.<br/>
+Sea-mats and Sea-mosses (<i>see</i> Polyzoa).<br/>
+Sea-shrubs (<i>see</i> Gorgonidæ).<br/>
+Sea-urchins (<i>see</i> Echinoidea).<br/>
+Sea-weeds, <a href="#page_80">80</a>, <a href="#page_81">81</a>,
+  <a href="#page_83">83</a>, <a href="#page_97">97</a>,
+  <a href="#page_136">136</a>, <a href="#page_164">164</a>,
+  <a href="#page_261">261</a>.<br/>
+Secondary period, <a href="#page_44">44</a>.<br/>
+Sedimentary rocks, <a href="#page_15">15</a>.<br/>
+<i>Semnopithecus</i>, <a href="#page_322">322</a>,
+  <a href="#page_331">331</a>.<br/>
+Septaria, <a href="#page_31">31</a>.<br/>
+<i>Sequoia</i>, <a href="#page_306">306</a>,
+  <a href="#page_309">309</a>, <a href="#page_310">310</a>;
+  <i>Couttsiœ</i>, <a href="#page_309">309</a>;
+  <i>gigantea</i>, <a href="#page_309">309</a>;
+  <i>Langsdorffii</i>, <a href="#page_309">309</a>.<br/>
+<i>Serolis</i>, <a href="#page_84">84</a>.<br/>
+Serpents (<i>see</i> Ophidia).<br/>
+<i>Serpulites</i>, <a href="#page_123">123</a>.<br/>
+Sewâlik Hills (<i>see</i> Siwâlik Hills).<br/>
+Sheep, <a href="#page_355">355</a>.<br/>
+Shell-sands, <a href="#page_19">19</a>.<br/>
+<i>Sigillaria</i>, <a href="#page_168">168</a>;
+  <i>Grœseri</i>, <a href="#page_168">168</a>.<br/>
+Sigillarioids, <a href="#page_136">136</a>,
+  <a href="#page_168">168</a>, <a href="#page_170">170</a>,
+  <a href="#page_196">196</a>.<br/>
+Silicates, infiltration of the shells of Foraminifera by,
+  <a href="#page_34">34</a>, <a href="#page_74">74</a>.<br/>
+Siliceous rocks, <a href="#page_20">20</a>,
+  <a href="#page_32">32</a>.<br/>
+Siliceous Sponges, <a href="#page_265">265</a>.<br/>
+Silicification, <a href="#page_13">13</a>,
+  <a href="#page_14">14</a>.<br/>
+Silurian period (<i>see</i> Lower Silurian and Upper Silurian),
+  <a href="#page_90">90-114</a>, <a href="#page_115">115-132</a>.<br/>
+<i>Simosaurus</i>, <a href="#page_219">219</a>; <i>Gaillardoti</i>,
+  <a href="#page_219">219</a>.<br/>
+<i>Siphonia</i>, <a href="#page_264">264</a>; <i>ficus</i>,
+  <a href="#page_265">265</a>.<br/>
+Siphonostomatous Univalves, <a href="#page_237">237</a>,
+  <a href="#page_271">271</a>, <a href="#page_293">293</a>.<br/>
+<i>Siphonotreta</i>, <a href="#page_110">110</a>.<br/>
+<i>Sirenia</i>, <a href="#page_299">299</a>,
+  <a href="#page_320">320</a>; of the Eocene,
+  <a href="#page_299">299</a>; of the Miocene,
+  <a href="#page_315">315</a>.<br/>
+<i>Siren lacertina</i>, <a href="#page_200">200</a>.<br/>
+<i>Sivatherium</i>, <a href="#page_318">318</a>;
+  <i>giganteum</i>, <a href="#page_319">319</a>.<br/>
+Siwâlik Hills, Miocene strata of,
+  <a href="#page_307">307</a>.<br/>
+Skiddaw Slates, <a href="#page_101">101</a>.<br/>
+Sloths, <a href="#page_315">315</a>,
+  <a href="#page_349">349-351</a>.<br/>
+<i>Smilax</i>, <a href="#page_308">308</a>.<br/>
+<i>Smithia</i>, <a href="#page_173">173</a>.<br/>
+Snakes (<i>see</i> Ophidia).<br/>
+Soft Tortoises, <a href="#page_296">296</a>.<br/>
+<i>Solarium</i>, <a href="#page_271">271</a>.<br/>
+Solenhofen Slates, <a href="#page_228">228</a>.<br/>
+Solitaire, <a href="#page_346">346</a>,
+  <a href="#page_348">348</a>.<br/>
+<i>Spalacotherium</i>, <a href="#page_254">254</a>.<br/>
+<i>Spatangus</i>, <a href="#page_311">311</a>.<br/>
+<i>Sphœrospongia</i>, <a href="#page_139">139</a>.<br/>
+<i>Sphagodus</i>, <a href="#page_130">130</a>.<br/>
+<i>Sphenodon</i>, <a href="#page_218">218</a>.<br/>
+<i>Sphenopteris</i>, <a href="#page_136">136</a>,
+  <a href="#page_165">165</a>, <a href="#page_196">196</a>.<br/>
+Spiders of the Coal-measures, <a href="#page_181">181</a>.<br/>
+Spider-shells, <a href="#page_237">237</a>.<br/>
+Spindle-shells, <a href="#page_237">237</a>.<br/>
+<i>Spirifera</i>, <a href="#page_125">125</a>,
+  <a href="#page_147">147</a>, <a href="#page_184">184</a>,
+  <a href="#page_198">198</a>, <a href="#page_234">234</a>;
+  <i>crispa</i>, <a href="#page_127">127</a>;
+  <i>disjuncta</i>, <a href="#page_147">147</a>;
+  <i>hysterica</i>, <a href="#page_126">126</a>;
+  <i>mucronata</i>, <a href="#page_147">147</a>;
+  <i>Niagarensis</i>, <a href="#page_127">127</a>;
+  <i>rostrata</i>, <a href="#page_235">235</a>;
+  <i>sculptilis</i>, <a href="#page_147">147</a>;
+  <i>trigonalis</i>, <a href="#page_185">185</a>.<br/>
+<i>Spiriferidœ</i>, <a href="#page_147">147</a>.<br/>
+<i>Spirophyton cauda-Galli</i>, <a href="#page_135">135</a>,
+  <a href="#page_164">164</a>.<br/>
+<i>Spirorbis</i>, <a href="#page_123">123</a>,
+  <a href="#page_143">143</a>, <a href="#page_178">178</a>;
+  <i>Arkonensis</i>, <a href="#page_144">144</a>;
+  <i>Carbonarus</i>, <a href="#page_178">178</a>;
+  <i>laxus</i>, <a href="#page_144">144</a>; <i>Lewisii</i>,
+  <a href="#page_123">123</a>; <i>omphalodes</i>,
+  <a href="#page_144">144</a>; <i>spinulifera</i>,
+  <a href="#page_144">144</a>.<br/>
+<i>Spirulirostra</i>, <a href="#page_312">312</a>.<br/>
+<i>Spondylus</i>, <a href="#page_269">269</a>;
+  <i>spinosus</i>, <a href="#page_270">270</a>.<br/>
+Sponges, of the Cambrian, <a href="#page_81">81</a>; of the
+  Lower Silurian, <a href="#page_98">98</a>; of the Upper
+  Silurian, <a href="#page_119">119</a>; of the Devonian,
+  <a href="#page_139">139</a>; of the Carboniferous,
+  <a href="#page_171">171</a>; of the Permian,
+  <a href="#page_197">197</a>; of the Trias,
+  <a href="#page_209">209</a>; of the Jurassic,
+  <a href="#page_230">230</a>; of the Cretaceous,
+  <a href="#page_264">264</a>, <a href="#page_265">265</a>.<br/>
+<i>Spongilla</i>, <a href="#page_197">197</a>.<br/>
+<i>Spongillopsis</i>, <a href="#page_197">197</a>.<br/>
+<i>Spongophyllum</i>, <a href="#page_173">173</a>.<br/>
+Spore-eases, of Cryptogams in the Ludlow rocks,
+  <a href="#page_118">118</a>; in the Coal,
+  <a href="#page_163">163</a>.<br/>
+Squirrels, <a href="#page_322">322</a>.<br/>
+<i>Stagonolepis</i>, <a href="#page_218">218</a>.<br/>
+Staircase-shell, <a href="#page_271">271</a>.<br/>
+Stalactite, <a href="#page_21">21</a>.<br/>
+Stalagmite, <a href="#page_21">21</a>.<br/>
+Star-corals, <a href="#page_231">231</a>.<br/>
+Star-fishes, <a href="#page_105">105</a>,
+  <a href="#page_120">120</a>, <a href="#page_210">210</a>.<br/>
+St Cassian Beds, <a href="#page_205">205</a>,
+  <a href="#page_206">206</a>.<br/>
+<i>Stephanophyllia</i>, <a href="#page_266">266</a>.<br/>
+<i>Stereognathus</i>, <a href="#page_253">253</a>,
+  <a href="#page_254">254</a>.<br/>
+<i>Stigmaria</i>, <a href="#page_169">169</a>;
+  <i>ficoides</i>, <a href="#page_169">169</a>.<br/>
+Stonesfield Slate, <a href="#page_227">227</a>;
+  Mammals of, <a href="#page_253">253</a>.<br/>
+Strata, contemporaneity of, <a href="#page_44">44</a>.<br/>
+Stratified rock, <a href="#page_15">15-18</a>.<br/>
+<i>Streptelasma</i>, <a href="#page_105">105</a>.<br/>
+<i>Streptorhynchus</i>, <a href="#page_198">198</a>.<br/>
+<i>Stromatopora</i>, <a href="#page_98">98</a>,
+  <a href="#page_99">99</a>, <a href="#page_118">118</a>,
+  <a href="#page_139">139</a>; <i>rugosa</i>,
+  <a href="#page_99">99</a>; <i>tuberculata</i>,
+  <a href="#page_140">140</a>.<br/>
+<i>Strombodes</i>, <a href="#page_119">119</a>;
+  <i>pentagonus</i>, <a href="#page_104">104</a>.<br/>
+<i>Strombus</i>, <a href="#page_271">271</a>.<br/>
+<i>Strophalosia</i>, <a href="#page_198">198</a>.<br/>
+<i>Strophodus</i>, <a href="#page_255">255</a>.<br/>
+<i>Strophomena</i>, <a href="#page_109">109</a>,
+  <a href="#page_110">110</a>; <i>alternata</i>,
+  <a href="#page_110">110</a>; <i>deltoidea</i>,
+  <a href="#page_109">109</a>; <i>filitexta</i>,
+  <a href="#page_110">110</a>; <i>rhomboidalis</i>,
+  <a href="#page_147">147</a>, <a href="#page_148">148</a>;
+  <i>Subplana</i>, <a href="#page_127">127</a>.<br/>
+Sub-Apennine Beds, <a href="#page_325">325</a>.<br/>
+Sub-Carboniferous rocks, <a href="#page_158">158</a>,
+  <a href="#page_161">161</a>.<br/>
+Succession of life upon the globe,
+  <a href="#page_367">367-374</a>.<br/>
+<i>Suida</i>, <a href="#page_302">302</a>,
+  <a href="#page_317">317</a>, <a href="#page_329">329</a>.<br/>
+Sulphate of lime, <a href="#page_22">22</a>.<br/>
+<i>Sus Erymanthius</i>, <a href="#page_317">317</a>;
+  <i>scrofa</i>, <a href="#page_354">354</a>.<br/>
+<i>Synastrœa</i>, <a href="#page_209">209</a>.<br/>
+<i>Synhelia Sharpeana</i>, <a href="#page_266">266</a>.<br/>
+<i>Synocladia</i>, <a href="#page_198">198</a>;
+  <i>virgulacea</i>, <a href="#page_198">198</a>.<br/>
+<i>Syringopora</i>, <a href="#page_119">119</a>,
+  <a href="#page_173">173</a>; <i>ramulosa</i>,
+  <a href="#page_174">174</a>.
+</p>
+
+<p class="index">
+Tabulate Corals, <a href="#page_104">104</a>; of the Lower
+  Silurian, <a href="#page_105">105</a>; of the Upper
+  Silurian, <a href="#page_142">142</a>; of the Devonian,
+  <a href="#page_142">142</a>; of the Carboniferous,
+  <a href="#page_172">172</a>; of the Permian,
+  <a href="#page_197">197</a>.<br/>
+<i>Talpa Europœa</i>, <a href="#page_336">336</a>.<br/>
+<i>Tapiridœ</i>, <a href="#page_300">300</a>.<br/>
+Tapirs, <a href="#page_300">300</a>.<br/>
+<i>Tapirus Arvernensis</i>, <a href="#page_327">327</a>.<br/>
+<i>Taxocrinus tuberculatus</i>, <a href="#page_122">122</a>.<br/>
+<i>Taxodium</i>, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>, <a href="#page_310">310</a>.<br/>
+<i>Teleosaurus</i>, <a href="#page_251">251</a>.<br/>
+Teleostean Fishes, <a href="#page_150">150</a>; of the
+  Cretaceous, <a href="#page_276">276</a>.<br/>
+<i>Telerpeton Elginense</i>, <a href="#page_218">218</a>.<br/>
+<i>Tellina proxima</i>, <a href="#page_338">338</a>.<br/>
+<i>Tentaculites</i>, <a href="#page_129">129</a>,
+  <a href="#page_148">148</a>; <i>ornatus</i>,
+  <a href="#page_129">129</a>.<br/>
+<i>Terebra</i>, <a href="#page_293">293</a>.<br/>
+<i>Terebratella</i>, <a href="#page_268">268</a>,
+  <i>Astleriana</i>, <a href="#page_268">268</a>.<br/>
+<i>Terebratula</i>, <a href="#page_184">184</a>,
+  <a href="#page_234">234</a>; <i>digona</i>,
+  <a href="#page_235">235</a>; <i>elongata</i>,
+  <a href="#page_168">168</a>; <i>hastata</i>,
+  <a href="#page_185">185</a>; <i>quadrifida</i>,
+  <a href="#page_235">235</a>; <i>sphœroidalis</i>,
+  <a href="#page_235">235</a>.<br/>
+<i>Terebratulina</i>, <a href="#page_268">268</a>;
+  <i>caput-serpentis</i>, <a href="#page_268">268</a>;
+  <i>striata</i>, <a href="#page_268">268</a>.<br/>
+Termites, <a href="#page_311">311</a>.<br/>
+Terrapins, <a href="#page_280">280</a>,
+  <a href="#page_296">296</a>.<br/>
+Tertiary period, <a href="#page_44">44</a>,
+  <a href="#page_284">284-287</a>.<br/>
+Tertiary rocks, classification of,
+  <a href="#page_284">284-287</a>.<br/>
+<a name="page_407"><span class="page">Page 407</span></a>
+<i>Testudinidœ</i>, <a href="#page_313">313</a>.<br/>
+Tetrabranchiate Cephalopods, <a href="#page_112">112</a>; of
+  the Cambrian, <a href="#page_89">89</a>; of the Lower
+  Silurian, <a href="#page_112">112-114</a>; of the Upper
+  Silurian, <a href="#page_130">130</a>; of the Devonian,
+  <a href="#page_149">149</a>; of the Carboniferous,
+  <a href="#page_186">186</a>, <a href="#page_187">187</a>;
+  of the Permian, <a href="#page_199">199</a>; of the Trias,
+  <a href="#page_212">212</a>; of the Jurassic,
+  <a href="#page_237">237-239</a>; of the Cretaceous,
+  <a href="#page_272">272-274</a>; of the Eocene,
+  <a href="#page_294">294</a>; of the Miocene,
+  <a href="#page_312">312</a>.<br/>
+<i>Textularia</i>, <a href="#page_22">22</a>,
+  <a href="#page_264">264</a>, <a href="#page_311">311</a>;
+  <i>Meyeriana</i>, <a href="#page_311">311</a>.<br/>
+Thanet Sands, <a href="#page_287">287</a>,
+  <a href="#page_288">288</a>.<br/>
+<i>Theca</i>, <a href="#page_88">88</a>,
+  <a href="#page_111">111</a>, <a href="#page_129">129</a>.<br/>
+<i>Theca Davidii</i>, <a href="#page_88">88</a>.<br/>
+<i>Thecidium</i>, <a href="#page_213">213</a>.<br/>
+Thecodont Reptiles, <a href="#page_218">218</a>.<br/>
+<i>Thecodontosaurus</i>, <a href="#page_200">200</a>,
+  <a href="#page_218">218</a>; <i>antiquus</i>,
+  <a href="#page_219">219</a>.<br/>
+<i>Thecosmilia annularis</i>, <a href="#page_231">231</a>.<br/>
+<i>Thelodus</i>, <a href="#page_131">131</a>.<br/>
+Theriodont Reptiles, <a href="#page_202">202</a>,
+  <a href="#page_220">220</a>.<br/>
+<i>Thylacoleo</i>, <a href="#page_349">349</a>.<br/>
+Tile-stones, <a href="#page_116">116</a>.<br/>
+<i>Titanotherium</i>, <a href="#page_316">316</a>.<br/>
+Toothed Birds, <a href="#page_281">281-283</a>.<br/>
+Tortoises, <a href="#page_202">202</a>,
+  <a href="#page_296">296</a>.<br/>
+<i>Tragoceras</i>, <a href="#page_318">318</a>.<br/>
+Travertine, <a href="#page_21">21</a>.<br/>
+Tree-Ferns, of the Devonian, <a href="#page_136">136</a>;
+  of the Coal-measures, <a href="#page_164">164</a>.<br/>
+Tremadoc Slates, <a href="#page_77">77-79</a>.<br/>
+<i>Trematis</i>, <a href="#page_110">110</a>.<br/>
+Trenton Limestone, <a href="#page_95">95</a>,
+  <a href="#page_96">96</a>.<br/>
+<i>Trianthrus Beckii</i>, <a href="#page_107">107</a>.<br/>
+Triassic period, <a href="#page_203">203</a>; rocks of, in
+  Britain, <a href="#page_204">204</a>; in Germany,
+  <a href="#page_204">204</a>; in the Austrian Alps,
+  <a href="#page_205">205</a>; in North America,
+  <a href="#page_205">205</a>; life of,
+  <a href="#page_206">206-224</a>.<br/>
+<i>Triconodon</i>, <a href="#page_254">254</a>.<br/>
+<i>Trigonia</i>, <a href="#page_235">235</a>,
+  <a href="#page_255">255</a>, <a href="#page_269">269</a>.<br/>
+<i>Trigoniadœ</i>, <a href="#page_198">198</a>,
+  <a href="#page_211">211</a>.<br/>
+<i>Trigonocarpum</i>, <a href="#page_170">170</a>;
+  <i>ovatum</i>, <a href="#page_170">170</a>.<br/>
+Trilobites, <a href="#page_84">84-87</a>; of the Cambrian,
+  <a href="#page_85">85</a>, <a href="#page_87">87</a>; of the
+  Lower Silurian, <a href="#page_107">107</a>,
+  <a href="#page_108">108</a>; of the Upper Silurian,
+  <a href="#page_123">123</a>, <a href="#page_124">124</a>; of
+  the Devonian, <a href="#page_144">144</a>,
+  <a href="#page_145">145</a>; of the Carboniferous,
+  <a href="#page_179">179</a>.<br/>
+<i>Trimerellidœ</i>, <a href="#page_127">127</a>.<br/>
+<i>Trinucleus</i>, <a href="#page_108">108</a>;
+  <i>concentricus</i>, <a href="#page_107">107</a>.<br/>
+<i>Trionycidœ</i>, <a href="#page_296">296</a>.<br/>
+<i>Triton</i>, <a href="#page_293">293</a>.<br/>
+<i>Trochocyathus</i>, <a href="#page_266">266</a>.<br/>
+<i>Trochonema</i>, <a href="#page_129">129</a>.<br/>
+<i>Trogontherium</i>, <a href="#page_361">361</a>;
+  <i>Cuvieri</i>, <a href="#page_336">336</a>,
+  <a href="#page_361">361</a>.<br/>
+Trumpet-shells, <a href="#page_293">293</a>.<br/>
+Tulip-tree, <a href="#page_262">262</a>,
+  <a href="#page_308">308</a>.<br/>
+<i>Turbinolia sulcata</i>, <a href="#page_292">292</a>.<br/>
+<i>Turbinolidœ</i>, <a href="#page_292">292</a>.<br/>
+<i>Turrilites</i>, <a href="#page_272">272</a>,
+  <a href="#page_273">273</a>; <i>catenulatus</i>,
+  <a href="#page_274">274</a>.<br/>
+<i>Turritella</i>, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>.<br/>
+Turtles, <a href="#page_202">202</a>,
+  <a href="#page_251">251</a>, <a href="#page_280">280</a>,
+  <a href="#page_296">296</a>.<br/>
+<i>Typhis tubifer</i>, <a href="#page_293">293</a>.
+</p>
+
+<p class="index">
+<i>Ullmania selaginoides</i>, <a href="#page_197">197</a>.<br/>
+Unconformability of strata, <a href="#page_48">48</a>.<br/>
+Under-clay of coal, <a href="#page_162">162</a>.<br/>
+<i>Ungulata</i>, of the Eocene, <a href="#page_300">300-303</a>;
+  of the Miocene, <a href="#page_315">315-319</a>; of the
+  Pliocene, <a href="#page_327">327-329</a>; of the
+  Post-Pliocene, <a href="#page_353">353-357</a>.<br/>
+Uniformity, doctrine of, <a href="#page_5">5-7</a>.<br/>
+<i>Unio</i>, <a href="#page_250">250</a>.<br/>
+Univalves (<i>see</i> Gasteropoda).<br/>
+Upper Cambrian, <a href="#page_77">77-79</a>; Chalk,
+  <a href="#page_259">259</a>; Cretaceous,
+  <a href="#page_257">257</a>, <a href="#page_259">259</a>;
+  Devonian, <a href="#page_135">135</a>; Eocene,
+  <a href="#page_287">287</a>, <a href="#page_288">288</a>;
+  Greensand, <a href="#page_258">258</a>; Helderberg,
+  <a href="#page_135">135</a>; Laurentian,
+  <a href="#page_66">66</a>; Llandovery,
+  <a href="#page_115">115</a>; Ludlow rock,
+  <a href="#page_116">116</a>; Miocene,
+  <a href="#page_305">305</a>; Oolites,
+  <a href="#page_227">227</a>; Silurian period,
+  <a href="#page_115">115</a>; rocks of, in Britain,
+  <a href="#page_115">115</a>, <a href="#page_116">116</a>;
+  in North America, <a href="#page_116">116-118</a>; life of,
+  <a href="#page_118">118-131</a>.<br/>
+<i>Ursus arctos</i>, <a href="#page_359">359</a>;
+  <i>Arvernensis</i>, <a href="#page_339">339</a>;
+  <i>ferox</i>, <a href="#page_359">359</a>;
+  <i>spelœa</i>, <a href="#page_360">360</a>.<br/>
+<i>Ursus</i>, <a href="#page_336">336</a>,
+  <a href="#page_356">356</a>.
+</p>
+
+<p class="index">
+Valley-gravels, high-level and low-level,
+  <a href="#page_339">339-341</a>.<br/>
+<i>Vanessa Pluto</i>, <a href="#page_312">312</a>.<br/>
+<i>Varanidœ</i>, <a href="#page_202">202</a>.<br/>
+Vegetation (<i>see</i> Plants).<br/>
+<i>Ventriculites</i>, <a href="#page_264">264</a>,
+  <a href="#page_265">265</a>; <i>simplex</i>,
+  <a href="#page_265">265</a>.<br/>
+Venus's Flower-basket, <a href="#page_265">265</a>.<br/>
+<i>Vermilia</i>, <a href="#page_197">197</a>.<br/>
+<i>Vespertilio Parisiensis</i>,
+  <a href="#page_304">304</a>, <a href="#page_305">305</a>.<br/>
+Vicksburg Beds, <a href="#page_289">289</a>.<br/>
+Vines, <a href="#page_306">306</a>,
+  <a href="#page_309">309</a>, <a href="#page_310">310</a>.<br/>
+Vitreous Sponges, <a href="#page_264">264</a>.<br/>
+<i>Voltzia</i>, <a href="#page_208">208</a>;
+  <i>heterophylla</i>, <a href="#page_209">209</a>.<br/>
+<i>Voluta</i>, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>; <i>elongata</i>,
+  <a href="#page_271">271</a>.<br/>
+Volutes, <a href="#page_271">271</a>,
+  <a href="#page_293">293</a>, <a href="#page_312">312</a>.
+</p>
+
+<p class="index">
+<i>Walchia</i>, <a href="#page_196">196</a>,
+  <a href="#page_197">197</a>; <i>piniformis</i>,
+  <a href="#page_196">196</a>.<br/>
+Walrus, <a href="#page_322">322</a>.<br/>
+Wealden Beds, <a href="#page_257">257</a>.<br/>
+<i>Wellingtonia</i>, <a href="#page_309">309</a>,
+  <a href="#page_310">310</a>.<br/>
+Wenlock Beds, <a href="#page_115">115</a>,
+  <a href="#page_117">117</a>; Limestone,
+  <a href="#page_115">115</a>; Shale,
+  <a href="#page_115">115</a>.<br/>
+Wentle-traps, <a href="#page_271">271</a>.<br/>
+Werfen Beds, <a href="#page_205">205</a>,
+  <a href="#page_206">206</a>.<br/>
+Whalebone Whales, <a href="#page_299">299</a>,
+  <a href="#page_315">315</a>.<br/>
+Whales, <a href="#page_299">299</a>,
+  <a href="#page_315">315</a>.<br/>
+Whelks, <a href="#page_237">237</a>.<br/>
+White Chalk, <a href="#page_259">259</a>; structure of,
+  <a href="#page_21">21</a>, <a href="#page_22">22</a>;
+  origin of, <a href="#page_23">23</a>,
+  <a href="#page_263">263</a>.<br/>
+White Crag, <a href="#page_324">324</a>.<br/>
+White River Beds, <a href="#page_307">307</a>.<br/>
+Wild Boar, <a href="#page_354">354</a>.<br/>
+<i>Williamsonia</i>, <a href="#page_230">230</a>.<br/>
+Winged Lizards (<i>see</i> Pterosauria).<br/>
+Winged Snails (<i>see</i> Pteropods).<br/>
+Wing-shells, <a href="#page_271">271</a>.<br/>
+Wolf, <a href="#page_336">336</a>,
+  <a href="#page_360">360</a>.<br/>
+Wolverine, <a href="#page_360">360</a>.<br/>
+Wombats, <a href="#page_348">348</a>.<br/>
+Woolhope Limestone, <a href="#page_115">115</a>.<br/>
+Woolly Rhinoceros, <a href="#page_339">339</a>,
+  <a href="#page_341">341</a>, <a href="#page_344">344</a>,
+  <a href="#page_353">353</a>.<br/>
+Woolwich and Reading Beds, <a href="#page_287">287</a>.<br/>
+Worm-burrows, <a href="#page_82">82</a>,
+  <a href="#page_83">83</a>, <a href="#page_123">123</a>.
+</p>
+
+<p class="index">
+<i>Xanthidia</i>, <a href="#page_138">138</a>,
+  <a href="#page_161">161</a>.<br/>
+<i>Xenoneura antiquorum</i>, <a href="#page_145">145</a>.<br/>
+<i>Xiphodon</i>, <a href="#page_303">303</a>.<br/>
+<i>Xylobius</i>, <a href="#page_182">182</a>;
+  <i>Sigillariœ</i>, <a href="#page_182">182</a>.
+</p>
+
+<p class="index">
+<i>Zamia spiralis</i>, <a href="#page_208">208</a>.<br/>
+<i>Zamites</i>, <a href="#page_208">208</a>,
+  <a href="#page_230">230</a>, <a href="#page_310">310</a>.<br/>
+<i>Zaphrentis</i>, <a href="#page_105">105</a>,
+  <a href="#page_119">119</a>, <a href="#page_142">142</a>,
+  <a href="#page_173">173</a>; <i>cornicula</i>,
+  <a href="#page_141">141</a>; <i>Stokesi</i>,
+  <a href="#page_104">104</a>; <i>vermicularis</i>,
+  <a href="#page_174">174</a>.<br/>
+<i>Zeacrinus</i>, <a href="#page_175">175</a>.<br/>
+Zechstein, <a href="#page_194">194</a>.<br/>
+<i>Zeuglodon</i>, <a href="#page_299">299</a>,
+  <a href="#page_315">315</a>; <i>cetoides</i>,
+  <a href="#page_299">200</a>, <a href="#page_300">300</a>.
+</p>
+
+<div>*** END OF THE PROJECT GUTENBERG EBOOK 14279 ***</div>
+</body>
+</html>
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