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+The Project Gutenberg EBook of Island Life, by Alfred Russel Wallace
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever. You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Island Life
+ Or the Phenomena and Causes of Insular Faunas and Floras
+
+Author: Alfred Russel Wallace
+
+Release Date: April 17, 2010 [EBook #32021]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK ISLAND LIFE ***
+
+
+
+
+Produced by StevenGibbs, Keith Edkins and the Online
+Distributed Proofreading Team at http://www.pgdp.net
+
+
+
+
+
+Transcriber's note: A few typographical errors have been corrected: they
+are listed at the end of the text.
+
+ * * * * *
+
+
+FRONTISPIECE
+
+[Illustration]
+
+ISLAND LIFE
+
+OR
+
+THE PHENOMENA AND CAUSES OF
+
+INSULAR FAUNAS AND FLORAS
+
+INCLUDING A REVISION AND ATTEMPTED SOLUTION OF
+THE PROBLEM OF
+
+GEOLOGICAL CLIMATES
+
+
+
+
+
+
+
+BY
+
+ALFRED RUSSEL WALLACE
+
+AUTHOR OF "THE MALAY ARCHIPELAGO," "THE GEOGRAPHICAL DISTRIBUTION OF
+ANIMALS,"
+"DARWINISM," ETC.
+
+
+
+
+
+_SECOND AND REVISED EDITION_
+
+London
+
+MACMILLAN AND CO.
+
+AND NEW YORK
+
+1895
+
+
+
+_The Right of Translation and Reproduction is Reserved_
+
+ * * * * *
+
+
+RICHARD CLAY AND SONS, LIMITED,
+LONDON AND BUNGAY.
+
+_First Edition printed 1880 (Med. 8vo).
+Second Edition 1892 (Extra cr. 8vo). Reprinted 1895._
+
+ * * * * *
+
+
+TO
+
+SIR JOSEPH DALTON HOOKER,
+
+K.C.S.I., C.B., F.R.S., ETC., ETC.
+
+WHO, MORE THAN ANY OTHER WRITER,
+
+HAS ADVANCED OUR KNOWLEDGE OF THE GEOGRAPHICAL
+
+DISTRIBUTION OF PLANTS, AND ESPECIALLY
+
+OF INSULAR FLORAS,
+
+I Dedicate this Volume;
+
+ON A KINDRED SUBJECT,
+
+AS A TOKEN OF ADMIRATION AND REGARD.
+
+ * * * * *
+
+
+{vi}
+
+CORRECTIONS IN PRESENT ISSUE.
+
+The first issue of this Edition being exhausted, the opportunity is taken
+of making a few corrections, the most important of which are here stated:--
+
+_Page_ 163. Statement modified as to supposed glaciation of South Africa.
+
+_Pages_ 174 and 338. Many geologists now hold that there was no great
+submergence during the glacial epoch. The passages referring to it have
+therefore been re-written.
+
+_Page_ 182. Colonel Fielden's explanation of the occurrence of large trees
+on shores and in recent drift in high latitudes, is now added.
+
+ " 272. A species of Carex peculiar to Bermuda is now given.
+
+ " 356. _Geomalacus maculosus_, as a peculiar British species, is now
+omitted.
+
+Verbal alterations have also been made at pages 41, 105, 356, and 360.
+
+ * * * * *
+
+
+{vii}
+
+PREFACE TO THE SECOND EDITION
+
+This edition has been carefully revised throughout, and owing to the great
+increase to our knowledge of the Natural History of some of the islands
+during the last twelve years considerable additions or alterations have
+been required. The more important of these changes are the following:--
+
+Chapter VII. The account of the migrations of animals and plants during and
+since the Glacial Epoch, has been modified to accord with newer
+information.
+
+Chapters VIII and IX. The discussion of the causes of Glacial Epochs and
+Mild Arctic Climates has been somewhat modified in view of the late Dr.
+Croll's remarks, and the argument rendered clearer.
+
+Chapter XIII. Several additions to the Fauna of the Galapagos have been
+noted.
+
+Chapter XV. Considerable additions have been made to this chapter embodying
+the recent discoveries of birds and insects new to the Sandwich Islands,
+while a much fuller account has been given of its highly peculiar and very
+interesting flora.
+
+Chapter XVI. Important additions and corrections have been made in the
+lists of peculiar British animals and plants embodying the most recent
+information.
+
+Chapter XVII. Very large additions have been made to the mammalia and birds
+of Borneo, and full lists of the peculiar species are given. {viii}
+
+Chapter XVIII. A more accurate account is given of the birds of Japan.
+
+Chapter XIX. The recent additions to the mammals and birds of Madagascar
+are embodied in this chapter, and a fuller sketch is given of the rich and
+peculiar flora of the island.
+
+Chapter XXI. and XXII. Some important additions have been made to these
+chapters owing to more accurate information as to the depth of the sea
+around New Zealand, and to the discovery of abundant remains of fossil
+plants of the tertiary and cretaceous periods both in New Zealand and
+Australia.
+
+In the body of the work I have in each case acknowledged the valuable
+information given me by naturalists of eminence in their various
+departments, and I return my best thanks to all who have so kindly assisted
+me. I am however indebted in a special manner to one gentleman--Mr. Theo.
+D. A. Cockerell, now Curator of the Museum of the Jamaica Institute--who
+supplied me with a large amount of information by searching the most recent
+works in the scientific libraries, by personal inquiries among naturalists,
+and also by giving me the benefit of his own copious notes and
+observations. Without his assistance it would have been difficult for me to
+have made the present edition so full and complete as I hope it now is. In
+a work of such wide range, and dealing with so large a body of facts some
+errors will doubtless be detected, though, I trust few of importance.
+
+ PARKSTONE, DORSET, _December, 1891_.
+
+ * * * * *
+
+
+{ix}
+
+PREFACE TO THE FIRST EDITION
+
+The present volume is the result of four years' additional thought and
+research on the lines laid down in my _Geographical Distribution of
+Animals_, and may be considered as a popular supplement to and completion
+of that work.
+
+It is, however, at the same time a complete work in itself: and, from the
+mode of treatment adopted, it will, I hope, be well calculated to bring
+before the intelligent reader the wide scope and varied interest of this
+branch of natural history. Although some of the earlier chapters deal with
+the same questions as my former volumes, they are here treated from a
+different point of view; and as the discussion of them is more elementary
+and at the same time tolerably full, it is hoped that they will prove both
+instructive and interesting. The plan of my larger work required that
+_genera_ only should be taken account of; in the present volume I often
+discuss the distribution of _species_, and this will help to render the
+work more intelligible to the unscientific reader.
+
+The full statement of the scope and object of the present essay given in
+the "Introductory" chapter, together with the "Summary" of the whole work
+and the general view of the more important arguments given in the
+"Conclusion," render it unnecessary for me to offer any further remarks on
+these points. I may, however, state {x} generally that, so far as I am able
+to judge, a real advance has here been made in the mode of treating
+problems in Geographical Distribution, owing to the firm establishment of a
+number of preliminary doctrines or "principles," which in many cases lead
+to a far simpler and yet more complete solution of such problems than have
+been hitherto possible. The most important of these doctrines are those
+which establish and define--(1) The former wide extension of all groups now
+discontinuous, as being a necessary result of "evolution"; (2) The
+permanence of the great features of the distribution of land and water on
+the earth's surface; and, (3) The nature and frequency of climatal changes
+throughout geological time.
+
+
+
+I have now only to thank the many friends and correspondents who have given
+me information or advice. Besides those whose assistance is acknowledged in
+the body of the work, I am especially indebted to four gentlemen who have
+been kind enough to read over the proofs of chapters dealing with questions
+on which they have special knowledge, giving me the benefit of valuable
+emendations and suggestions. Mr. Edward R. Alston has looked over those
+parts of the earlier chapters which relate to the mammals of Europe and the
+North Temperate zone; Mr. S. B. J. Skertchley, of the Geological Survey,
+has read the chapters which discuss the glacial epoch and other geological
+questions; Professor A. Newton has looked over the passages referring to
+the birds of the Madagascar group; while Sir Joseph D. Hooker has given me
+the invaluable benefit of his remarks on my two chapters dealing with the
+New Zealand flora.
+
+ CROYDON, _August, 1880_.
+
+ * * * * *
+
+
+{xi}
+
+CONTENTS
+
+PART I
+
+THE DISPERSAL OF ORGANISMS; ITS PHENOMENA, LAWS, AND CAUSES
+
+CHAPTER I
+
+INTRODUCTORY
+
+Remarkable Contrasts in the Distribution of Animals--Britain and
+Japan--Australia and New Zealand--Bali and Lombok--Florida and Bahama
+Islands--Brazil and Africa--Borneo, Madagascar, and Celebes--Problems in
+Distribution to be found in every Country--Can be Solved only by the
+Combination of many distinct lines of inquiry, Biological and
+Physical--Islands offer the best Subjects for the Study of
+Distribution--Outline of the Subjects to be discussed in the Present
+Volume.
+
+_Pages_ 3-11
+
+CHAPTER II
+
+THE ELEMENTARY FACTS OF DISTRIBUTION.
+
+Importance of Locality as an Essential Character of Species--Areas of
+Distribution--Extent and Limitations of Specific Areas--Specific Range of
+Birds--Generic Areas--Separate and Overlapping Areas--The Species of Tits
+as illustrating Areas of Distribution--The Distribution of the Species of
+Jays--Discontinuous Generic Areas--Peculiarities of Generic and Family
+Distribution--General Features of Overlapping and Discontinuous
+Areas--Restricted Areas of Families--The Distribution of Orders
+
+_Pages_ 12-30
+
+{xii}
+
+CHAPTER III
+
+CLASSIFICATION OF THE FACTS OF DISTRIBUTION.--ZOOLOGICAL REGIONS
+
+The Geographical Divisions of the Globe do not Correspond to Zoological
+Divisions--The Range of British Mammals as Indicating a Zoological
+Region--Range of East Asian and North African Mammals--The Range of British
+Birds--Range of East Asian Birds--The Limits of the Palæarctic
+Region--Characteristic Features of the Palæarctic Region--Definition and
+Characteristic Groups of the Ethiopian Region--Of the Oriental Region--Of
+the Australian Region--Of the Nearctic Region--Of the Neotropical
+Region--Comparison of Zoological Regions with the Geographical Divisions of
+the Globe
+
+_Pages_ 31-54
+
+CHAPTER IV
+
+EVOLUTION AS THE KEY TO DISTRIBUTION
+
+Importance of the Doctrine of Evolution--The Origin of New
+Species--Variation in Animals--The amount of Variation in North American
+Birds--How New Species Arise from a Variable Species--Definition and Origin
+of Genera--Cause of the Extinction of Species--The Rise and Decay of
+Species and Genera--Discontinuous Specific Areas, why Rare--Discontinuity
+of the Area of Parus Palustris--Discontinuity of Emberiza Schoeniclus--The
+European and Japanese Jays--Supposed examples of Discontinuity among North
+American Birds--Distribution and Antiquity of Families--Discontinuity a
+Proof of Antiquity--Concluding remarks
+
+_Pages_ 55-71
+
+CHAPTER V
+
+THE POWERS OF DISPERSAL OF ANIMALS AND PLANTS
+
+Statement of the General Question of Dispersal--The Ocean as a Barrier to
+the Dispersal of Mammals--The Dispersal of Birds--The Dispersal of
+Reptiles--The Dispersal of Insects--The Dispersal of Land Mollusca--Great
+Antiquity of Land-shells--Causes Favouring the Abundance of
+Land-shells--The Dispersal of Plants--Special Adaptability of Seeds for
+Dispersal--Birds as Agents in the Dispersal of Seeds--Ocean Currents as
+Agents in Plant Dispersal--Dispersal along Mountain Chains--Antiquity of
+Plants as Effecting their Distribution
+
+_Pages_ 72-82
+
+CHAPTER VI
+
+GEOGRAPHICAL AND GEOLOGICAL CHANGES: THE PERMANENCE OF CONTINENTS
+
+Changes of Land and Sea, their Nature and Extent--Shore-Deposits and
+Stratified Rocks--The Movements of Continents--Supposed Oceanic {xiii}
+Formations; the Origin of Chalk--Fresh-water and Shore-deposits as Proving
+the Permanence of Continents--Oceanic Islands as Indications of the
+Permanence of Continents and Oceans--General Stability of Continents with
+Constant Change of Form--Effect of Continental Changes on the Distribution
+of Animals--Changed Distribution Proved by the Extinct Animals of Different
+Epochs--Summary of Evidence for the General Permanence of Continents and
+Oceans.
+
+_Pages_ 83-105
+
+CHAPTER VII
+
+CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DISPERSAL OF ORGANISMS: THE
+GLACIAL EPOCH
+
+Proofs of the Recent Occurrence of a Glacial Epoch--Moraines--Travelled
+Blocks--Glacial Deposits of Scotland: the "Till"--Inferences from the
+Glacial Phenomena of Scotland--Glacial Phenomena of North America--Effects
+of the Glacial Epoch on Animal Life--Warm and Cold Periods--Palæontological
+Evidence of Alternate Cold and Warm Periods--Evidence of Interglacial Warm
+Periods on the Continent and in North America--Migrations and Extinctions
+of Organisms Caused by the Glacial Epoch
+
+_Pages_ 106-124
+
+CHAPTER VIII
+
+THE CAUSES OF GLACIAL EPOCHS
+
+Various Suggested Causes--Astronomical Causes of Changes of
+Climate--Difference of Temperature Caused by Varying Distances of the
+Sun--Properties of Air and Water, Snow and Ice, in Relation to
+Climate--Effects of Snow on Climate--High Land and Great Moisture Essential
+to the Initiation of a Glacial Epoch--Perpetual Snow nowhere Exists on
+Lowlands--Conditions Determining the Presence or Absence of Perpetual
+Snow--Efficiency of Astronomical causes in Producing Glaciation--Action of
+Meteorological Causes in Intensifying Glaciation--Summary of Causes of
+Glaciation--Effect of Clouds and Fog in Cutting off the Sun's Heat--South
+Temperate America as Illustrating the Influence of Astronomical Causes on
+Climate--Geographical Changes how far a Cause of Glaciation--Land Acting as
+a Barrier to Ocean-currents--The Theory of Interglacial Periods and their
+Probable Character--Probable Effect of Winter in _aphelion_ on the Climate
+of Britain--The Essential Principle of Climatal Change Restated--Probable
+Date of the Last Glacial Epoch--Changes of the Sea-level Dependent on
+Glaciation--The Planet Mars as Bearing on the Theory of Excentricity as a
+Cause of Glacial Epochs
+
+_Pages_ 125-168
+
+{xiv}
+
+CHAPTER IX
+
+ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARCTIC REGIONS
+
+Mr. Croll's Views on Ancient Glacial Epochs--Effects of Denudation in
+Destroying the Evidence of Remote Glacial Epochs--Rise of Sea-level
+Connected with Glacial Epochs a Cause of Further Denudation--What Evidence
+of Early Glacial Epochs may be Expected--Evidences of Ice-action During the
+Tertiary Period--The Weight of the Negative Evidence--Temperate Climates in
+the Arctic Regions--The Miocene Arctic Flora--Mild Arctic Climates of the
+Cretaceous Period--Stratigraphical Evidence of Long-continued Mild Arctic
+Conditions--The Causes of Mild Arctic Climates--Geographical Conditions
+Favouring Mild Northern Climates in Tertiary Times--The Indian Ocean as a
+Source of Heat in Tertiary Times--Condition of North America During the
+Tertiary Period--Effect of High Excentricity on Warm Polar
+Climates--Evidences as to Climate in the Secondary and Palæozoic
+Epochs--Warm Arctic Climates in Early Secondary and Palæozoic
+Times--Conclusions as to the Climates of Secondary and Tertiary
+Periods--General View of Geological Climates as Dependent on the Physical
+Features of the Earth's Surface--Estimate of the Comparative Effects of
+Geographical and Physical Causes in Producing Changes of Climate.
+
+_Pages_ 169-209
+
+CHAPTER X
+
+THE EARTH'S AGE, AND THE RATE OF DEVELOPMENT OF ANIMALS AND PLANTS
+
+Various Estimates of Geological Time--Denudation and Deposition of Strata
+as a Measure of Time--How to Estimate the Thickness of the Sedimentary
+Rocks--How to Estimate the Average Rate of Deposition of the Sedimentary
+Rocks--The Rate of Geological Change Probably Greater in very Remote
+Times--Value of the Preceding Estimate of Geological Time--Organic
+Modification Dependent on Change of Conditions--Geographical Mutations as a
+Motive Power in Bringing about Organic Changes--Climatal Revolutions as an
+Agent in Producing Organic Changes--Present Condition of the Earth One of
+Exceptional Stability as Regards Climate--Date of Last Glacial Epoch and
+its Bearing on the Measurement of Geological Time--Concluding Remarks
+
+_Pages_ 210-237
+
+{xv}
+
+PART II
+
+INSULAR FAUNAS AND FLORAS
+
+CHAPTER XI
+
+THE CLASSIFICATION OF ISLANDS
+
+Importance of Islands in the Study of the Distribution of
+Organisms--Classification of Islands with Reference to
+Distribution--Continental Islands--Oceanic Islands
+
+_Pages_ 241-245
+
+CHAPTER XII
+
+OCEANIC ISLANDS:--THE AZORES AND BERMUDA
+
+_The Azores, or Western Islands_
+
+Position and Physical Features--Chief Zoological Features of the
+Azores--Birds--Origin of the Azorean Bird-fauna--Insects of the
+Azores--Land-shells of the Azores--The Flora of the Azores--The Dispersal
+of Seeds--Birds as seed-carriers--Facilities for Dispersal of Azorean
+Plants--Important Deduction from the Peculiarities of the Azorean Fauna and
+Flora
+
+_Pages_ 246-262
+
+_Bermuda_
+
+Position and Physical Features--The Red Clay of Bermuda--Zoology of
+Bermuda--Birds of Bermuda--Comparison of the Bird-faunas of Bermuda and the
+Azores--Insects of Bermuda--Land Mollusca--Flora of Bermuda--Concluding
+Remarks on the Azores and Bermuda
+
+_Pages_ 263-274
+
+CHAPTER XIII
+
+THE GALAPAGOS ISLANDS
+
+Position and Physical Features--Absence of Indigenous Mammalia and
+Amphibia--Reptiles--Birds--Insects and Land-shells--The Keeling Islands as
+Illustrating the Manner in which Oceanic Islands are Peopled--Flora of the
+Galapagos--Origin of the Flora of the Galapagos--Concluding remarks
+
+_Pages_ 273-291
+
+CHAPTER XIV
+
+ST. HELENA
+
+Position and Physical Features of St. Helena--Change Effected by European
+Occupation--The Insects of St. Helena--Coleoptera--Peculiarities and Origin
+of the Coleoptera of St. Helena--Land-shells of St. Helena--Absence of
+Fresh-water Organisms--Native Vegetation of St. Helena--The Relations of
+the St. Helena Compositæ--Concluding Remarks on St. Helena
+
+_Pages_ 292-309
+
+{xvi}
+
+CHAPTER XV
+
+THE SANDWICH ISLANDS
+
+Position and Physical Features--Zoology of the Sandwich
+Islands--Birds--Reptiles--Land-shells--Insects--Vegetation of the Sandwich
+Islands--Peculiar Features of the Hawaiian Flora--Antiquity of the Hawaiian
+Fauna and Flora--Concluding Observations on the Fauna and Flora of the
+Sandwich Islands--General Remarks on Oceanic Islands
+
+_Pages_ 310-330
+
+CHAPTER XVI
+
+CONTINENTAL ISLANDS OF RECENT ORIGIN: GREAT BRITAIN
+
+Characteristic Features of Recent Continental Islands--Recent Physical
+Changes of the British Isles--Proofs of Former Elevation--Submerged
+Forests--Buried River Channels--Time of Last Union with the Continent--Why
+Britain is Poor in Species--Peculiar British Birds---Fresh-water
+Fishes--Cause of Great Speciality in Fishes--Peculiar British
+Insects--Lepidoptera Confined to the British Isles--Peculiarities of the
+Isle of Man Lepidoptera--Coleoptera Confined to the British
+Isles--Trichoptera Peculiar to the British Isles--Land and Fresh-water
+Shells--Peculiarities of the British Flora--Peculiarities of the Irish
+Flora--Peculiar British Mosses and Hepaticæ--Concluding Remarks on the
+Peculiarities of the British Fauna and Flora
+
+_Pages_ 331-372
+
+CHAPTER XVII
+
+BORNEO AND JAVA
+
+Position and Physical Features of Borneo--Zoological Features of Borneo:
+Mammalia--Birds--The Affinities of the Borneo Fauna--Java, its Position and
+Physical Features--General Character of the Fauna of Java--Differences
+Between the Fauna of Java and that of the other Malay Islands--Special
+Relations of the Javan Fauna to that of the Asiatic Continent--Past
+Geographical Changes of Java and Borneo--The Philippine Islands--Concluding
+Remarks on the Malay Islands
+
+_Pages_ 373-390
+
+CHAPTER XVIII
+
+JAPAN AND FORMOSA
+
+Japan, its Position and Physical Features--Zoological Features of
+Japan--Mammalia--Birds--Birds Common to Great Britain and Japan--Birds
+Peculiar to Japan--Japan Birds Recurring in Distant
+Areas--Formosa--Physical Features of Formosa--Animal Life of
+Formosa--Mammalia--Land Birds Peculiar to Formosa--Formosan Birds Recurring
+in India or Malaya--Comparison of Faunas of Hainan, Formosa, and
+Japan--General Remarks on Recent Continental Islands
+
+_Pages_ 391-410
+
+{xvii}
+
+CHAPTER XIX
+
+ANCIENT CONTINENTAL ISLANDS: THE MADAGASCAR GROUP
+
+Remarks on Ancient Continental Islands--Physical Features of
+Madagascar--Biological Features of Madagascar--Mammalia--Reptiles--Relation
+of Madagascar to Africa--Early History of Africa and Madagascar--Anomalies
+of Distribution and how to Explain Them--The Birds of Madagascar as
+Indicating a Supposed Lemurian Continent--Submerged Islands Between
+Madagascar and India--Concluding Remarks on "Lemuria"--The Mascarene
+Islands--The Comoro Islands--The Seychelles Archipelago--Birds of the
+Seychelles--Reptiles and Amphibia--Fresh-water Fishes--Land
+Shells--Mauritius, Bourbon, and Rodriguez--Birds--Extinct Birds and their
+Probable Origin--Reptiles--Flora of Madagascar and the Mascarene
+Islands--Curious Relations of Mascarene Plants--Endemic Genera of Mauritius
+and Seychelles--Fragmentary Character of the Mascarene Flora--Flora of
+Madagascar Allied to that of South Africa--Preponderance of Ferns in the
+Mascarene Flora--Concluding Remarks on the Madagascar Group
+
+_Pages_ 411-449
+
+CHAPTER XX
+
+ANOMALOUS ISLANDS: CELEBES
+
+Anomalous Relations of Celebes--Physical Features of the Island--Zoological
+Character of the Islands Around Celebes--The Malayan and Australian
+Banks--Zoology of Celebes: Mammalia--Probable Derivation of the Mammals of
+Celebes--Birds of Celebes--Bird-types Peculiar to Celebes--Celebes not
+Strictly a Continental Island--Peculiarities of the Insects of
+Celebes--Himalayan Types of Birds and Butterflies in Celebes--Peculiarities
+of Shape and Colour of Celebesian Butterflies--Concluding Remarks--Appendix
+on the Birds of Celebes
+
+_Pages_ 450-470
+
+CHAPTER XXI
+
+ANOMALOUS ISLANDS: NEW ZEALAND
+
+Position and Physical Features of New Zealand--Zoological Character of New
+Zealand--Mammalia--Wingless Birds Living and Extinct--Recent Existence of
+the Moa--Past Changes of New Zealand deduced from its Wingless Birds--Birds
+and Reptiles of New Zealand--Conclusions from the Peculiarities of the New
+Zealand Fauna
+
+_Pages_ 471-486
+
+{xviii}
+
+CHAPTER XXII
+
+THE FLORA OF NEW ZEALAND: ITS AFFINITIES AND PROBABLE ORIGIN
+
+Relations of the New Zealand Flora to that of Australia--General Features
+of the Australian Flora--The Floras of South-eastern and South-western
+Australia--Geological Explanation of the Differences of these Two
+Floras--The Origin of the Australian Element in the New Zealand
+Flora--Tropical Character of the New Zealand Flora Explained--Species
+Common to New Zealand and Australia mostly Temperate Forms--Why Easily
+Dispersed Plants have often Restricted Ranges--Summary and Conclusion on
+the New Zealand Flora
+
+_Pages_ 487-508
+
+CHAPTER XXIII
+
+ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS
+
+European Species and Genera of Plants in the Southern
+Hemisphere--Aggressive Power of the Scandinavian Flora--Means by which
+Plants have Migrated from North to South--Newly Moved Soil as Affording
+Temporary Stations to Migrating Plants--Elevation and Depression of the
+Snow-line as Aiding the Migration of Plants--Changes of Climate Favourable
+to Migration--The Migration from North to South has been Long going
+on--Geological Changes as Aiding Migration--Proofs of Migration by way of
+the Andes--Proofs of Migration by way of the Himalayas and Southern
+Asia--Proofs of Migration by way of the African Highlands--Supposed
+Connection of South Africa and Australia--The Endemic Genera of Plants in
+New Zealand--The Absence of Southern Types from the Northern
+Hemisphere--Concluding Remarks on the New Zealand and South Temperate
+Floras
+
+_Pages_ 509-530
+
+CHAPTER XXIV
+
+SUMMARY AND CONCLUSION
+
+The Present Volume is the Development and Application of a
+Theory--Statement of the Biological and Physical Causes of
+Dispersal--Investigation of the Facts of Dispersal--Of the Means of
+Dispersal--Of Geographical Changes Affecting Dispersal--Of Climatal Changes
+Affecting Dispersal--The Glacial Epoch and its Causes--Alleged Ancient
+Glacial Epochs--Warm Polar Climates and their Causes--Conclusions as to
+Geological Climates--How Far Different from those of Mr. Croll--Supposed
+Limitations of Geological Time--Time Amply Sufficient both for Geological
+and Biological Development--Insular Faunas and Floras--The North Atlantic
+Islands--The Galapagos--St. Helena and the Sandwich Islands--Great Britain
+as a Recent Continental Island--Borneo and Java--Japan and
+Formosa--Madagascar as an Ancient Continental Island--Celebes and New
+Zealand as Anomalous Islands--The Flora of New Zealand and its Origin--The
+European Element in the South Temperate Floras--Concluding Remarks
+
+_Pages_ 531-545
+
+ * * * * *
+
+
+{xix}
+
+MAPS AND ILLUSTRATIONS
+
+ PAGE
+
+ 1. MAP SHOWING THE DISTRIBUTION OF THE TRUE JAYS _Frontispiece._
+
+ 2. MAP SHOWING THE ZOOLOGICAL REGIONS _To face_ 31
+
+ 3. MAP SHOWING THE DISTRIBUTION OF _PARUS PALUSTRIS_ _To face_ 66
+
+ 4. A GLACIER WITH MORAINES (From Sir C. Lyell's _Principles
+ of Geology_) 109
+
+ 5. MAP OF THE ANCIENT RHONE GLACIER (From Sir C. Lyell's
+ _Antiquity of Man_) 110
+
+ 6. DIAGRAM SHOWING THE EFFECTS OF EXCENTRICITY AND PRECESSION
+ ON CLIMATE 127
+
+ 7. DIAGRAM OF EXCENTRICITY AND PRECESSION 129
+
+ 8. MAP SHOWING THE EXTENT OF THE NORTH AND SOUTH POLAR ICE 138
+
+ 9. DIAGRAM SHOWING CHANGES OF EXCENTRICITY DURING THREE MILLION
+ YEARS 171
+
+ 10. OUTLINE MAP OF THE AZORES 248
+
+ 11. MAP OF BERMUDA AND THE AMERICAN COAST 263
+
+ 12. SECTION OF BERMUDA AND ADJACENT SEA-BOTTOM 264
+
+ {xx}
+ 13. MAP OF THE GALAPAGOS AND ADJACENT COASTS OF SOUTH AMERICA 276
+
+ 14. MAP OF THE GALAPAGOS 277
+
+ 15. MAP OF THE SOUTH ATLANTIC, SHOWING POSITION OF ST. HELENA 293
+
+ 16. MAP OF THE SANDWICH ISLANDS 311
+
+ 17. MAP OF THE NORTH PACIFIC, WITH ITS SUBMERGED BANKS 312
+
+ 18. MAP SHOWING THE BANK CONNECTING BRITAIN WITH THE CONTINENT 333
+
+ 19. MAP OF BORNEO AND JAVA, SHOWING THE GREAT SUBMARINE BANK OF
+ SOUTH-EASTERN ASIA 373
+
+ 20. MAP OF JAPAN AND FORMOSA 392
+
+ 21. PHYSICAL SKETCH MAP OF MADAGASCAR (From _Nature_) 413
+
+ 22. MAP OF MADAGASCAR GROUP, SHOWING DEPTHS OF SEA 415
+
+ 23. MAP OF THE INDIAN OCEAN 424
+
+ 24. MAP OF CELEBES AND THE SURROUNDING ISLANDS 451
+
+ 25. MAP SHOWING DEPTHS OF SEA AROUND AUSTRALIA AND NEW ZEALAND 471
+
+ 26. MAP SHOWING THE PROBABLE CONDITION OF AUSTRALIA DURING THE
+ CRETACEOUS EPOCH 496
+
+ * * * * *
+
+
+ISLAND LIFE
+
+PART I
+
+_THE DISPERSAL OF ORGANISMS_
+
+_ITS PHENOMENA, LAWS, AND CAUSES_
+
+{3}
+
+CHAPTER I
+
+INTRODUCTORY
+
+ Remarkable Contrasts in distribution of Animals--Britain and
+ Japan--Australia and New Zealand--Bali and Lombok--Florida and Bahama
+ Islands--Brazil and Africa--Borneo, Madagascar, and Celebes--Problems
+ in distribution to be found in every country--Can be solved only by the
+ combination of many distinct lines of inquiry, biological and
+ physical--Islands offer the best subjects for the study of
+ distribution--Outline of the subjects to be discussed in the present
+ volume.
+
+When an Englishman travels by the nearest sea-route from Great Britain to
+Northern Japan he passes by countries very unlike his own, both in aspect
+and natural productions. The sunny isles of the Mediterranean, the sands
+and date-palms of Egypt, the arid rocks of Aden, the cocoa groves of
+Ceylon, the tiger-haunted jungles of Malacca and Singapore, the fertile
+plains and volcanic peaks of Luzon, the forest-clad mountains of Formosa,
+and the bare hills of China, pass successively in review; till after a
+circuitous voyage of thirteen thousand miles he finds himself at Hakodadi
+in Japan. He is now separated from his starting-point by the whole width of
+Europe and Northern Asia, by an almost endless succession of plains and
+mountains, arid deserts or icy plateaux, yet when he visits the interior of
+the country he sees so many familiar natural objects that he can hardly
+help fancying he is close to his home. He finds the woods and fields
+tenanted by tits, hedge-sparrows, wrens, wagtails, larks, redbreasts, {4}
+thrushes, buntings, and house-sparrows, some absolutely identical with our
+own feathered friends, others so closely resembling them that it requires a
+practised ornithologist to tell the difference. If he is fond of insects he
+notices many butterflies and a host of beetles which, though on close
+examination they are found to be distinct from ours, are yet of the same
+general aspect, and seem just what might be expected in any part of Europe.
+There are also of course many birds and insects which are quite new and
+peculiar, but these are by no means so numerous or conspicuous as to remove
+the general impression of a wonderful resemblance between the productions
+of such remote islands as Britain and Yesso.
+
+Now let an inhabitant of Australia sail to New Zealand, a distance of less
+than thirteen hundred miles, and he will find himself in a country whose
+productions are totally unlike those of his own. Kangaroos and wombats
+there are none, the birds are almost all entirely new, insects are very
+scarce and quite unlike the handsome or strange Australian forms, while
+even the vegetation is all changed, and no gum-tree, or wattle, or
+grass-tree meets the traveller's eye.
+
+But there are some more striking cases even than this, of the diversity of
+the productions of countries not far apart. In the Malay Archipelago there
+are two islands, named Bali and Lombok, each about as large as Corsica, and
+separated by a strait only fifteen miles wide at its narrowest part. Yet
+these islands differ far more from each other in their birds and quadrupeds
+than do England and Japan. The birds of the one are extremely _unlike_
+those of the other, the difference being such as to strike even the most
+ordinary observer. Bali has red and green woodpeckers, barbets,
+weaver-birds, and black-and-white magpie-robins, none of which are found in
+Lombok, where, however, we find screaming cockatoos and friar-birds, and
+the strange mound-building megapodes, which are all equally unknown in
+Bali. Many of the kingfishers, crow-shrikes, and other birds, though of the
+same general form, are of very distinct species; and though a considerable
+number of birds are the same in both islands the difference {5} is none the
+less remarkable--as proving that mere distance is one of the least
+important of the causes which have determined the likeness or unlikeness in
+the animals of different countries.
+
+In the western hemisphere we find equally striking examples. The Eastern
+United States possess very peculiar and interesting plants and animals, the
+vegetation becoming more luxuriant as we go south but not altering in
+essential character, so that when we reach Alabama or Florida we still find
+ourselves in the midst of pines, oaks, sumachs, magnolias, vines, and other
+characteristic forms of the temperate flora; while the birds, insects, and
+land-shells are of the same general character with those found further
+north.[1] But if we now cross over the narrow strait, about fifty miles
+wide, which separates Florida from the Bahama Islands, we find ourselves in
+a totally different country, surrounded by a vegetation which is
+essentially tropical and generally identical with that of Cuba. The change
+is most striking, because there is little difference of climate, of soil,
+or apparently of position, to account for it; and when we find that the
+birds, the insects, and especially the land-shells of the Bahamas are
+almost all West Indian, while the North American types of plants and
+animals have almost all completely disappeared, we shall be convinced that
+such differences and resemblances cannot be due to existing conditions, but
+must depend upon laws and causes to which mere proximity of position offers
+no clue.
+
+Hardly less uncertain and irregular are the effects of climate. Hot
+countries usually differ widely from cold ones in all their organic forms;
+but the difference is by no means constant, nor does it bear any proportion
+to difference of temperature. Between frigid Canada and sub-tropical
+Florida there are less marked differences in the animal productions than
+between Florida and Cuba or Yucatan, so much more alike in climate and so
+much nearer together. So the differences between the birds and quadrupeds
+of temperate Tasmania and tropical North {6} Australia are slight and
+unimportant as compared with the enormous differences we find when we pass
+from the latter country to equally tropical Java. If we compare
+corresponding portions of different continents, we find no indication that
+the almost perfect similarity of climate and general conditions has any
+tendency to produce similarity in the animal world. The equatorial parts of
+Brazil and of the West Coast of Africa are almost identical in climate and
+in luxuriance of vegetation, but their animal life is totally diverse. In
+the former we have tapirs, sloths, and prehensile-tailed monkeys; in the
+latter elephants, antelopes, and man-like apes; while among birds, the
+toucans, chatterers, and humming-birds of Brazil are replaced by the
+plantain-eaters, bee-eaters, and sun-birds of Africa. Parts of
+South-temperate America, South Africa, and South Australia, correspond
+closely in climate; yet the birds and quadrupeds of these three districts
+are as completely unlike each other as those of any parts of the world that
+can be named.
+
+If we visit the great islands of the globe, we find that they present
+similar anomalies in their animal productions, for while some exactly
+resemble the nearest continents others are widely different. Thus the
+quadrupeds, birds and insects of Borneo correspond very closely to those of
+the Asiatic continent, while those of Madagascar are extremely unlike
+African forms, although the distance from the continent is less in the
+latter case than in the former. And if we compare the three great islands
+Sumatra, Borneo, and Celebes--lying as it were side by side in the same
+ocean--we find that the two former, although furthest apart, have almost
+identical productions, while the two latter, though closer together, are
+more unlike than Britain and Japan situated in different oceans and
+separated by the largest of the great continents.
+
+These examples will illustrate the kind of questions it is the object of
+the present work to deal with. Every continent, every country, and every
+island on the globe, offers similar problems of greater or less complexity
+and interest, and the time has now arrived when their solution can be
+attempted with some prospect of success. Many {7} years study of this class
+of subjects has convinced me that there is no short and easy method of
+dealing with them; because they are, in their very nature, the visible
+outcome and residual product of the whole past history of the earth. If we
+take the organic productions of a small island, or of any very limited
+tract of country, such as a moderate-sized country parish, we have, in
+their relations and affinities--in the fact that they are _there_ and
+others are _not_ there, a problem which involves all the migrations of
+these species and their ancestral forms--all the vicissitudes of climate
+and all the changes of sea and land which have affected those
+migrations--the whole series of actions and reactions which have determined
+the preservation of some forms and the extinction of others,--in fact the
+whole history of the earth, inorganic and organic, throughout a large
+portion of geological time.
+
+We shall perhaps better exhibit the scope and complexity of the subject,
+and show that any intelligent study of it was almost impossible till quite
+recently, if we concisely enumerate the great mass of facts and the number
+of scientific theories or principles which are necessary for its
+elucidation.
+
+We require then in the first place an adequate knowledge of the fauna and
+flora of the whole world, and even a detailed knowledge of many parts of
+it, including the islands of more special interest and their adjacent
+continents. This kind of knowledge is of very slow growth, and is still
+very imperfect;[2] and in many cases it can {8} never now be obtained owing
+to the reckless destruction of forests and with them of countless species
+of plants and animals. In the next place we require a true and natural
+classification of animals and plants, so that we may know their real
+affinities; and it is only now that this is being generally arrived at. We
+further have to make use of the theory of "descent with modification" as
+the only possible key to the interpretation of the facts of distribution,
+and this theory has only been generally accepted within the last twenty
+years. It is evident that, so long as the belief in "special creations" of
+each species prevailed, no explanation of the complex facts of distribution
+_could_ be arrived at or even conceived; for if each species was created
+where it is now found no further inquiry can take us beyond that fact, and
+there is an end of the whole matter. Another important factor in our
+interpretation of the phenomena of distribution, is a knowledge of the
+extinct forms that have inhabited each country during the tertiary and
+secondary periods of geology. New facts of this kind are daily coming to
+light, but except as regards Europe, North America, and parts of India,
+they are extremely scanty; and even in the best-known countries the record
+itself is often very defective and fragmentary. Yet we have already
+obtained remarkable evidence of the migrations of many animals and plants
+in past ages, throwing an often unexpected light on the actual distribution
+of many groups.[3] By this means alone can we obtain positive evidence of
+the past migrations of organisms; and when, as too frequently is the case,
+this is altogether wanting, we {9} have to trust to collateral evidence and
+more or less probable hypothetical explanations. Hardly less valuable is
+the evidence of stratigraphical geology; for this often shows us what parts
+of a country have been submerged at certain epochs, and thus enables us to
+prove that certain areas have been long isolated and the fauna and flora
+allowed time for special development. Here, too, our knowledge is
+exceedingly imperfect, though the blanks upon the geological map of the
+world are yearly diminishing in extent. Lastly, as a most valuable
+supplement to geology, we require to know approximately, the depth and
+contour of the ocean-bed, since this affords an important clue to the
+former existence of now-submerged lands, uniting islands to continents, or
+affording intermediate stations which have aided the migrations of many
+organisms. This kind of information has only been partially obtained during
+the last few years; and it will be seen in the latter part of this volume,
+that some of the most recent deep-sea soundings have afforded a basis for
+an explanation of one of the most difficult and interesting questions in
+geographical biology--the origin of the fauna and flora of New Zealand.
+
+Such are the various classes of evidence that bear directly on the question
+of the distribution of organisms; but there are others of even a more
+fundamental character, and the importance of which is only now beginning to
+be recognised by students of nature. These are, firstly, the wonderful
+alterations of climate which have occurred in the temperate and polar
+zones, as proved by the evidences of glaciation in the one and of luxuriant
+vegetation in the other; and, secondly, the theory of the permanence of
+existing continents and oceans. If glacial epochs in temperate lands and
+mild climates near the poles have, as now believed by men of eminence,
+occurred several times over in the past history of the earth, the effects
+of such great and repeated changes, both on the migration, modification,
+and extinction, of species, must have been of overwhelming importance--of
+more importance perhaps than even the geological changes of sea and land.
+It is therefore necessary to consider the evidence for these climatal
+changes; {10} and then, by a critical examination of their possible causes,
+to ascertain whether they were isolated phenomena, were due to recurrent
+cosmical actions, or were the result of a great system of terrestrial
+development. The latter is the conclusion we arrive at; and this conclusion
+brings with it the conviction, that in the theory which accounts for both
+glacial epochs and warm polar climates, we have the key to explain and
+harmonize many of the most anomalous biological and geological phenomena,
+and one which is especially valuable for the light it throws on the
+dispersal and existing distribution of organisms. The other important
+theory, or rather corollary from the preceding theory--that of the
+permanence of oceans and the general stability of continents throughout all
+geological time, is as yet very imperfectly understood, and seems, in fact,
+to many persons in the nature of a paradox. The evidence for it, however,
+appears to me to be conclusive; and it is certainly the most fundamental
+question in regard to the subject we have to deal with: since, if we once
+admit that continents and oceans may have changed places over and over
+again (as many writers maintain), we lose all power of reasoning on the
+migrations of ancestral forms of life, and are at the mercy of every wild
+theorist who chooses to imagine the former existence of a now-submerged
+continent to explain the existing distribution of a group of frogs or a
+genus of beetles.
+
+As already shown by the illustrative examples adduced in this chapter, some
+of the most remarkable and interesting facts in the distribution and
+affinities of organic forms are presented by islands in relation to each
+other and to the surrounding continents. The study of the productions of
+the Galapagos--so peculiar, and yet so decidedly related to the American
+continent--appears to have had a powerful influence in determining the
+direction of Mr. Darwin's researches into the origin of species; and every
+naturalist who studies them has always been struck by the unexpected
+relations or singular anomalies which are so often found to characterize
+the fauna and flora of islands. Yet their full importance in connection
+with the history of the earth and its inhabitants has hardly yet {11} been
+recognised; and it is in order to direct the attention of naturalists to
+this most promising field of research, that I restrict myself in this
+volume to an elucidation of some of the problems they present to us. By far
+the larger part of the islands of the globe are but portions of continents
+undergoing some of the various changes to which they are ever subject; and
+the correlative proposition, that every portion of our continents has again
+and again passed through insular conditions, has not been sufficiently
+considered, but is, I believe, the statement of a great and most suggestive
+truth, and one which lies at the foundation of all accurate conception of
+the physical and organic changes which have resulted in the present state
+of the earth.
+
+
+
+The indications now given of the scope and purpose of the present volume
+renders it evident that, before we can proceed to the discussion of the
+remarkable phenomena presented by insular faunas and floras, and the
+complex causes which have produced them, we must go through a series of
+preliminary studies, adapted to give us a command of the more important
+facts and principles on which the solution of such problems depends. The
+succeeding eight chapters will therefore be devoted to the explanation of
+the mode of distribution, variation, modification, and dispersal, of
+species and groups, illustrated by facts and examples; of the true nature
+of geological change as affecting continents and islands; of changes of
+climate, their nature, causes, and effects; of the duration of geological
+time and the rate of organic development.
+
+ * * * * *
+
+
+{12}
+
+CHAPTER II
+
+THE ELEMENTARY FACTS OF DISTRIBUTION
+
+ Importance of Locality as an essential character of Species--Areas of
+ Distribution--Extent and Limitations of Specific Areas--Specific range
+ of Birds--Generic Areas--Separate and overlapping areas--The species of
+ Tits as illustrating Areas of Distribution--The distribution of the
+ species of Jays--Discontinuous generic areas--Peculiarities of generic
+ and family distribution--General features of overlapping and
+ discontinuous areas--Restricted areas of Families--The distribution of
+ Orders.
+
+So long as it was believed that the several species of animals and plants
+were "special creations," and had been formed expressly to inhabit the
+countries in which they are now found, their habitat was an ultimate fact
+which required no explanation. It was assumed that every animal was
+_exactly_ adapted to the climate and surroundings amid which it lived, and
+that the only, or, at all events, the chief reason why it did not inhabit
+another country was, that the climate or general conditions of that country
+were not suitable to it, but in what the unsuitability consisted we could
+rarely hope to discover. Hence the exact locality of any species was not
+thought of much importance from a scientific point of view, and the idea
+that anything could be learnt by a comparative study of different floras
+and faunas never entered the minds of the older naturalists.
+
+But so soon as the theory of evolution came to be generally adopted, and it
+was seen that each animal could only have come into existence in some area
+where ancestral {13} forms closely allied to it already lived, a real and
+important relation was established between an animal and its native
+country, and a new set of problems at once sprang into existence. From the
+old point of view the _diversities_ of animal life in the separate
+continents, even where physical conditions were almost identical, was the
+fact that excited astonishment; but seen by the light of the evolution
+theory, it is the _resemblances_ rather than the diversities in these
+distant continents and islands that are most difficult to explain. It thus
+comes to be admitted that a knowledge of the exact area occupied by a
+species or a group is a real portion of its natural history, of as much
+importance as its habits, its structure, or its affinities; and that we can
+never arrive at any trustworthy conclusions as to how the present state of
+the organic world was brought about, until we have ascertained with some
+accuracy the general laws of the distribution of living things over the
+earth's surface.
+
+_Areas of Distribution._--Every species of animal has a certain area of
+distribution to which, as a rule, it is permanently confined, although, no
+doubt, the limits of its range fluctuate somewhat from year to year, and in
+some exceptional cases may be considerably altered in a few years or
+centuries. Each species is moreover usually limited to one continuous area,
+over the whole of which it is more or less frequently to be met with, but
+there are many apparent and some real exceptions to this rule. Some animals
+are so adapted to certain kinds of country--as to forests or marshes,
+mountains or deserts--that they cannot, permanently, live elsewhere. These
+may be found scattered over a wide area in suitable spots only, but can
+hardly on that account be said to have several distinct areas of
+distribution. As an example we may name the chamois, which lives only on
+high mountains, but is found in the Pyrenees, the Alps, the Carpathians, in
+some of the Greek mountains and the Caucasus. The variable hare is another
+and more remarkable case, being found all over Northern Europe and Asia
+beyond lat. 55°, and also in Scotland and Ireland. In central Europe it is
+unknown till we come to the Alps, the Pyrenees, and the Caucasus, where it
+again appears. This is one of the best cases known of the {14}
+discontinuous distribution of a _species_, there being a gap of about a
+thousand miles between its southern limits in Russia, and its reappearance
+in the Alps. There are of course numerous instances in which species occur
+in two or more islands, or in an island and continent, and are thus
+rendered discontinuous by the sea, but these involve questions of changes
+in sea and land which we shall have to consider further on. Other cases are
+believed to exist of still wider separation of a species, as with the marsh
+titmice and the reed buntings of Europe and Japan, where similar forms are
+found in the extreme localities, while distinct varieties or sub-species,
+inhabit the intervening districts.
+
+_Extent and Limitations of Specific Areas._--Leaving for the present these
+cases of want of continuity in a species, we find the most wide difference
+between the extent of country occupied, varying in fact from a few square
+miles to almost the entire land surface of the globe. Among the mammalia,
+however, the same species seldom inhabits both the old and new worlds,
+unless they are strictly arctic animals, as the reindeer, the elk, the
+arctic fox, the glutton, the ermine, and some others. The common wolf of
+Europe and Northern Asia is thought by many naturalists to be identical
+with the variously coloured wolves of North America extending from the
+Arctic Ocean to Mexico, in which case this will have perhaps the widest
+range of any species of mammal. Little doubt exists as to the identity of
+the brown bears and the beavers of Europe and North America; but all these
+species range up to the arctic circle, and there is no example of a mammal
+universally admitted to be identical yet confined to the temperate zones of
+the two hemispheres. Among the undisputed species of mammalia the leopard
+has an enormous range, extending all over Africa and South Asia to Borneo
+and the east of China, and thus having probably the widest range of any
+known mammal. The winged mammalia have not usually very wide ranges, there
+being only one bat common to the Old and New Worlds. This is a British
+species, _Vesperugo serotinus_, which is found over the larger part of
+North America, Europe and Asia, as far {15} as Pekin, and even extends into
+tropical Africa, thus rivalling the leopard and the wolf in the extent of
+country it occupies.
+
+Of very restricted ranges there are many examples, but some of these are
+subject to doubts as to the distinctness of the species or as to its
+geographical limits being really known. In Europe we have a distinct
+species of ibex (_Capra Pyrenaica_) confined to the Pyrenean mountains,
+while the true marmot is restricted to the Alpine range. More remarkable is
+the Pyrenean water-mole (_Mygale Pyrenaica_), a curious small insectivorous
+animal found only in a few places in the northern valleys of the Pyrenees.
+In islands there are many cases of undoubted restriction of species to a
+small area, but these involve a different question from the range of
+species on continents where there is no _apparent_ obstacle to their wider
+extension.
+
+_Specific range of Birds._--Among birds we find instances of much wider
+range of species, which is only what might be expected considering their
+powers of flight; but, what is very curious, we also find more striking
+(though perhaps not more frequent) examples of extreme limitation of range
+among birds than among mammals. Of the former phenomenon perhaps the most
+remarkable case is that afforded by the osprey or fishing-hawk, which
+ranges over the greater portion of all the continents, as far as Brazil,
+South Africa, the Malay Islands, and Tasmania. The barn owl (_Strix
+flammea_) has nearly as wide a range, but in this case there is more
+diversity of opinion as to the specific difference of many of the forms
+inhabiting remote countries, some of which seem undoubtedly to be distinct.
+Among passerine birds the raven has probably the widest range, extending
+from the arctic regions to Texas and New Mexico in America, and to North
+India and Lake Baikal in Asia; while the little northern willow-wren
+(_Phylloscopus borealis_) ranges from arctic Norway across Asia to Alaska,
+and southward to Ceylon, China, Borneo, and Timor.
+
+Of very restricted continental ranges the best examples in Europe are, the
+little blue magpie (_Cyanopica cooki_) confined to the central portions of
+the Spanish peninsula; and the Italian sparrow found only in Italy and
+Corsica. {16} In Asia, Palestine affords some examples of birds of very
+restricted range--a beautiful sun-bird (_Nectarinea osea_) a peculiar
+starling (_Amydrus tristramii_) and some others, being almost or quite
+confined to the warmer portions of the valley of the Jordan. In the
+Himalayas there are numbers of birds which have very restricted ranges, but
+those of the Neilgherries are perhaps better known, several species of
+laughing thrushes and some other birds being found only on the summits of
+these mountains. The most wonderfully restricted ranges are, however, to be
+found among the humming-birds of tropical America. The great volcanic peaks
+of Chimborazo and Pichincha have each a peculiar species of humming-bird
+confined to a belt just below the limits of perpetual snow, while the
+extinct volcano of Chiriqui in Veragua has a species confined to its wooded
+crater. One of the most strange and beautiful of the humming-birds
+(_Loddigesia mirabilis_) was obtained once only, more than forty years ago,
+near Chachapoyas in the Andes of northern Peru; and though Mr. Gould sent
+many drawings of the bird to people visiting the district and for many
+years offered a high reward for a specimen, no other has ever been seen![4]
+
+The above details will sufficiently explain what is meant by the "specific
+area" or range of a species. The very wide and very narrow ranges are
+exceptional, the great majority of species both of mammals and birds
+ranging over moderately wide areas, which present no striking contrasts in
+climate and physical conditions. Thus a large proportion of European birds
+range over the whole continent in an east and west direction, but
+considerable numbers are restricted either to the northern or the southern
+half. In Africa some species range over all the continent south of the
+desert, while large numbers are restricted to the equatorial forests, or to
+the upland plains. In North America, if we exclude the tropical and the
+arctic portions, a considerable number of species range over all the
+temperate parts of the continent, while still {17} more are restricted to
+the east, the centre, or the west, respectively.
+
+_Generic Areas._--Having thus obtained a tolerably clear idea of the main
+facts as to the distribution of isolated species, let us now consider those
+collections of closely-allied species termed genera. What a genus is will
+be sufficiently understood by a few illustrations. All the different kinds
+of dogs, jackals, and wolves belong to the dog genus, Canis; the tiger,
+lion, leopard, jaguar, and the wild cats, to the cat genus, Felis; the
+blackbird, song-thrush, missel-thrush, fieldfare, and many others to the
+thrush genus, Turdus; the crow, rook, raven, and jackdaw, to the crow
+genus, Corvus; but the magpie belongs to another, though closely-allied
+genus, Pica, distinguished by the different form and proportions of its
+wings and tail from all the species of the crow genus. The number of
+species in a genus varies greatly, from one up to several hundreds. The
+giraffe, the glutton, the walrus, the bearded reedling, the secretary-bird,
+and many others, have no close allies, and each forms a genus by itself.
+The beaver genus, Castor, and the camel genus, Camelus, each consist of two
+species. On the other hand, the deer genus, Cervus has forty species; the
+mouse and rat genus, Mus more than a hundred species; and there is about
+the same number of the thrush genus; while among the lower classes of
+animals genera are often very extensive, the fine genus Papilio, or
+swallow-tailed butterflies, containing more than four hundred species; and
+Cicindela, which includes our native tiger beetles, has about the same
+number. Many genera of shells are very extensive, and one of them--the
+genus Helix, including the commonest snails, and ranging all over the
+world--is probably the most extensive in the animal kingdom, numbering
+about two thousand described species.[5]
+
+_Separate and Overlapping Areas._--The species of a genus are distributed
+in two ways. Either they occupy distinct areas which do not touch each
+other and are sometimes widely separated, or they touch and occasionally
+overlap {18} each other, each species occupying an area of its own which
+rarely coincides exactly with that of any other species of the same genus.
+In some cases, when a river, a mountain-chain, or a change of conditions as
+from pasture to desert or forest, determines the range of species, the
+areas of two species of the same genus may just meet, one beginning where
+the other ends; but this is comparatively rare. It occurs, however, in the
+Amazon valley, where several species of monkeys, birds, and insects come up
+to the south bank of the river but do not pass it, while allied species
+come to the north bank, which in like manner forms their boundary. As
+examples we may mention that one of the Saki monkeys (_Pithecia monachus?_)
+comes up to the south bank of the Upper Amazon, while immediately we cross
+over to the north bank we find another species (_Pithecia rufibarbata?_).
+Among birds we have the green jacamar (_Galbula viridis_), abundant on the
+north bank of the Lower Amazon, while on the south bank we have two allied
+species (_Galbula rufoviridis_ and _G. cyaneicollis_); and among insects we
+have at Santarem on the south bank of the Amazon, the beautiful blue
+butterfly, _Callithea sapphira_, while almost opposite to it, at
+Monte-alegre, an allied species, _Callithea Leprieuri_ is alone found.
+Perhaps the most interesting and best known case of a series of allied
+species, whose ranges are separate but conterminous, is that of the
+beautiful South American wading birds, called trumpeters, and forming the
+genus Psophia. There are five species, all found in the Amazon valley, but
+each limited to a well-marked district bounded by great rivers. On the
+north bank of the Amazon there are two species, one in its lower valley
+extending up to the Rio Negro; and the other in the central part of the
+valley beyond that river; while to the south of the Amazon there are three,
+one above the Madeira, one below it, and a third near Para, probably
+separated from the last by the Tocantins river.
+
+Overlapping areas among the species of a genus is a more common phenomenon,
+and is almost universal where these species are numerous in the same
+continent. It is, however, exceedingly irregular, so that we often find one
+{19} species extending over a considerable portion of the area occupied by
+the genus and including the entire areas of some of the other species. So
+little has been done to work out accurately the limits of species that it
+is very difficult to give examples. One of the best is to be found in the
+genus _Dendroeca_, a group of American wood-warblers. These little birds
+all migrate in the winter into the tropical regions, but in the summer they
+come north, each having its particular range. Thus, _D. dominica_ comes as
+far as the middle Eastern States, _D. coerulea_ keeps west of the
+Alleghanies, _D. discolor_ comes to Michigan and New England; four other
+species go farther north in Canada, while several extend to the borders of
+the Arctic zone.
+
+_The Species of Tits as Illustrating Areas of Distribution._--In our own
+hemisphere the overlapping of allied species may be well illustrated by the
+various kinds of titmice, constituting the genus Parus, several of which
+are among our best known English birds. The great titmouse (_Parus major_)
+has the widest range of all, extending from the Arctic circle to Algeria,
+Palestine, and Persia, and from Ireland right across Siberia to the Ochotsk
+sea, probably following the great northern forest belt. It does not extend
+into China and Japan, where distinct species are found. Next in extent of
+range is the coal tit (_Parus ater_) which inhabits all Europe from the
+Mediterranean to about 64° N. latitude, in Asia Minor to the Lebanon and
+Caucasus, and across Siberia to Amoorland and Japan. The marsh tit (_Parus
+palustris_) inhabits temperate and south Europe from 61° N. latitude in
+Norway to Poland and South-west Russia, and in the south from Spain to Asia
+Minor. Closely allied to this--of which it is probably only a variety or
+sub-species--is the northern marsh tit (_Parus borealis_), which overlaps
+the last in Norway and Sweden, and also in South Russia and the Alps, but
+extends further north into Lapland and North Russia, and thence probably in
+a south-easterly direction across Central Asia to North China. Yet another
+closely-allied species (_Parus camtschatkensis_) ranges from North-eastern
+Russia across Northern Siberia to Lake Baikal and to Hakodadi in Japan,
+thus overlapping _Parus borealis_ in the {20} western portion of its area.
+Our little favourite, the blue tit (_Parus coeruleus_) ranges over all
+Europe from the Arctic circle to the Mediterranean, and on to Asia Minor
+and Persia, but does not seem to pass beyond the Ural mountains. Its lovely
+eastern ally the azure tit (_Parus cyaneus_) overlaps the range of _P.
+coeruleus_ in Western Europe as far as St. Petersburg and Austria, rarely
+straggling to Denmark, while it stretches all across Central Asia between
+the latitudes 35° and 56° N. as far as the Amoor valley. Besides these
+wide-ranging species there are several others which are more restricted.
+_Parus teneriffæ_, a beautiful dark blue form of our blue tit, inhabits
+North-west Africa and the Canaries; _Parus ledouci_, closely allied to our
+coal tit, is found only in Algeria; _Parus lugubris_, allied to the marsh
+tit, is confined to South-east Europe and Asia Minor, from Hungary and
+South Russia to Palestine; and _Parus cinctus_, another allied form, is
+confined to the extreme north in Lapland, Finland, and perhaps Northern
+Russia and Siberia. Another beautiful little bird, the crested titmouse
+(_Parus cristatus_) is sometimes placed in a separate genus. It inhabits
+nearly all Central and South Europe, wherever there are pine forests, from
+64° N. latitude to Austria and North Italy, and in the west to Spain and
+Gibraltar, while in the east it does not pass the Urals and the Caucasus
+range. Its nearest allies are in the high Himalayas.
+
+These are all the European tits, but there are many others inhabiting Asia,
+Africa, and North America; so that the genus Parus has a very wide range,
+in Asia to Ceylon and the Malay Islands, in Africa to the Cape, and in
+North America to the highlands of Mexico.
+
+_The Distribution of the Species of Jays._--Owing to the very wide range of
+several of the tits, the uncertainty of the specific distinction of others,
+and the difficulty in many cases of ascertaining their actual distribution,
+it has not been found practicable to illustrate this genus by means of a
+map. For this purpose we have chosen the genus Garrulus or the jays, in
+which the species are less numerous, the specific areas less extensive, and
+the species generally better defined; while being large and handsome {21}
+birds they are sure to have been collected, or at least noticed, wherever
+they occur. There are, so far as yet known, twelve species of true jays,
+occupying an area extending from Western Europe to Eastern Asia and Japan,
+and nowhere passing the Arctic circle to the north, or the tropic of Cancer
+to the south, so that they constitute one of the most typical of the
+Palæarctic[6] genera. The following are the species, beginning with the
+most westerly and proceeding towards the east. The numbers prefixed to each
+species correspond to those on the coloured map which forms the
+frontispiece to this volume.
+
+1. _Garrulus glandarius._--The common jay, inhabits the British Isles and
+all Europe except the extreme north, extending also into North Africa,
+where it has been observed in many parts of Algeria. It occurs near
+Constantinople, but apparently not in Asia Minor; and in Russia, up to, but
+not beyond, the Urals. The jays being woodland birds are not found in open
+plains or barren uplands, and their distribution is hence by no means
+uniform within the area they actually occupy.
+
+2. _Garrulus cervicalis._--The Algerian jay, is a very distinct species
+inhabiting a limited area in North Africa, and found in some places along
+with the common species.
+
+3. _Garrulus krynicki._--The black-headed jay, is closely allied to the
+common species, but quite distinct, inhabiting a comparatively small area
+in South-eastern Europe, and Western Asia.
+
+4. _Garrulus atricapillus._--The Syrian jay, is very closely allied to the
+last, and inhabits an adjoining area in Syria, Palestine, and Southern
+Persia.
+
+5. _Garrulus hyrcanus._--The Persian jay, is a small species allied to our
+jay and only known from the Elburz Mountains in the north of Persia.
+
+6. _Garrulus brandti._--Brandt's jay, is a very distinct species, having an
+extensive range across Asia from the Ural Mountains to North China,
+Mandchuria, and the northern island of Japan, and also crossing the Urals
+into {22} Russia where it has been found as far west as Kazan in districts
+where the common jay also occurs.
+
+7. _Garrulus lanceolatus._--The black-throated jay, is a very distinct form
+known only from the North-western Himalayas and Nepal, common about Simla,
+and extending into Cashmere beyond the range of the next species.
+
+8. _Garrulus bispecularis._--The Himalayan jay is also very distinct,
+having the head coloured like the back, and not striped as in all the
+western species. It inhabits the Himalayas east of Cashmere, but is more
+abundant in the western than the eastern division, though according to the
+Abbé David it reaches Moupin in East Thibet.
+
+9. _Garrulus sinensis._--The Chinese jay, is very closely allied to the
+Himalayan, of which it is sometimes classed as a sub-species. It seems to
+be found in all the southern mountains of China, from Foochow on the east
+to Sze-chuen and East Thibet on the west, as it is recorded from Moupin by
+the Abbé David as well as the Himalayan bird--a tolerable proof that it is
+a distinct form.
+
+10. _Garrulus taivanus._--The Formosan jay is a very close ally of the
+preceding, confined to the island of Formosa.
+
+11. _Garrulus japonicus._--The Japanese jay is nearly allied to our common
+British species, being somewhat smaller and less brightly coloured, and
+with black orbits; yet these are the most widely separated species of the
+genus. According to Mr. Seebohm this species is equally allied to the
+Chinese and Siberian jays.
+
+In the accompanying map (see frontispiece) we have laid down the
+distribution of each species so far as it can be ascertained from the works
+of Sharpe and Dresser for Europe, Jerdon for India, Swinhoe for China, and
+Mr. Seebohm's recent work for Japan. There is, however, much uncertainty in
+many places, and gaps have to be filled up conjecturally, while such a
+large part of Asia is still very imperfectly explored, that considerable
+modifications may have to be made when the country becomes more accurately
+known. But though details may be modified we can hardly suppose that the
+great features of the several specific areas, or their relations to each
+other {23} will be much affected; and these are what we have chiefly to
+consider as bearing on the questions here discussed.
+
+The first thing that strikes us on looking at the map, is, the small amount
+of overlapping of the several areas, and the isolation of many of the
+species; while the next most striking feature is the manner in which the
+Asiatic species almost surround a vast area in which no jays are found. The
+only species with large areas, are the European _G. glandarius_ and the
+Asiatic _G. Brandti_. The former has three species overlapping it--in
+Algeria, in South-eastern and North-eastern Europe respectively. The Syrian
+jay (No. 4), is not known to occur anywhere with the black-headed jay (No.
+3), and perhaps the two areas do not meet. The Persian jay (No. 5), is
+quite isolated. The Himalayan and Chinese jays (Nos. 7, 8, and 9) form a
+group which are isolated from the rest of the genus; while the Japanese jay
+(No. 11), is also completely isolated as regards the European jays to which
+it is nearly allied. These peculiarities of distribution are no doubt in
+part dependent on the habits of the jays, which live only in well-wooded
+districts, among deciduous trees, and are essentially non-migratory in
+their habits, though sometimes moving southwards in winter. This will
+explain their absence from the vast desert area of Central Asia, but it
+will not account for the gap between the North and South Chinese species,
+nor for the absence of jays from the wooded hills of Turkestan, where Mr.
+N. A. Severtzoff collected assiduously, obtaining 384 species of birds but
+no jay. These peculiarities, and the fact that jays are never very abundant
+anywhere, seem to indicate that the genus is now a decaying one, and that
+it has at no very distant epoch occupied a larger and more continuous area,
+such as that of the genus Parus at the present day.
+
+_Discontinuous generic Areas._--It is not very easy to find good examples
+of genera whose species occupy two or more quite disconnected areas, for
+though such cases may not be rare, we are seldom in a position to mark out
+the limits of the several species with sufficient accuracy. The best and
+most remarkable case among European birds is {24} that of the blue magpies,
+forming the genus Cyanopica. One species (_C. cooki_) is confined (as
+already stated) to the wooded and mountainous districts of Spain and
+Portugal, while the only other species of the genus (_C. cyanus_) is found
+far away in North-eastern Asia and Japan, so that the two species are
+separated by about 5,000 miles of continuous land. Another case is that of
+the curious little water-moles forming the genus Mygale, one species _M.
+muscovitica_, being found only on the banks of the Volga and Don in
+South-eastern Russia, while the other, _M. pyrenaica_, is confined to
+streams on the northern side of the Pyrenees. In tropical America there are
+four different kinds of bell-birds belonging to the genus Chasmorhynchus,
+each of which appears to inhabit a restricted area completely separated
+from the others. The most northerly is _C. tricarunculatus_ of Costa Rica
+and Veragua, a brown bird with a white head and three long caruncles
+growing upwards at the base of the beak. Next comes _C. variegatus_, in
+Venezuela, a white bird with a brown head and numerous caruncles on the
+throat, perhaps conterminous with the last; in Guiana, extending to near
+the mouth of the Rio Negro, we have _C. niveus_, the bell-bird described by
+Waterton, which is pure white, with a single long fleshy caruncle at the
+base of the beak; the last species, _C. nudicollis_, inhabits South-east
+Brazil, and is also white, but with black stripes over the eyes, and with a
+naked throat. These birds are about the size of thrushes, and are all
+remarkable for their loud, ringing notes, like a bell or a blow on an
+anvil, as well as for their peculiar colours. They are therefore known to
+the native Indians wherever they exist, and we may be the more sure that
+they do not spread over the intervening areas where they have never been
+found, and where the natives know nothing of them.
+
+A good example of isolated species of a group nearer home, is afforded by
+the snow-partridges of the genus Tetraogallus. One species inhabits the
+Caucasus range and nowhere else, keeping to the higher slopes from 6,000 to
+11,000 feet above the sea, and accompanying the ibex in its wanderings, as
+both feed on the same plants. Another {25} has a wider range in Asia Minor
+and Persia, from the Taurus mountains to the South-east corner of the
+Caspian Sea; a third species inhabits the Western Himalayas, between the
+forests and perpetual snow, extending eastwards to Nepal; while a fourth is
+found on the north side of the mountains in Thibet, and the ranges of these
+two perhaps overlap; the last species inhabit the Altai mountains, and like
+the two first appears to be completely separated from all its allies.
+
+There are some few still more extraordinary cases in which the species of
+one genus are separated in remote continents or islands. The most striking
+of these is that of the tapirs, forming the genus Tapirus, of which there
+are two or three species in South America, and one very distinct species in
+Malacca and Borneo, separated by nearly half the circumference of the
+globe. Another example among quadrupeds is a peculiar genus of moles named
+Urotrichus, of which one species inhabits Japan and the other British
+Columbia. The cuckoo-like honey-guides, forming the genus Indicator, are
+tolerably abundant in tropical Africa, but there are two outlying species,
+one in the Eastern Himalaya mountains, the other in Borneo, both very rare,
+and recently an allied species has been found in the Malay peninsula. The
+beautiful blue and green thrush-tits forming the genus Cochoa, have two
+species in the Eastern Himalayas and Eastern China, while the third is
+confined to Java; the curious genus Eupetes, supposed to be allied to the
+dippers, has one species in Sumatra and Malacca, while four other species
+are found two thousand miles distant in New Guinea; lastly, the lovely
+ground-thrushes of the genus Pitta, range from Hindostan to Australia,
+while a single species, far removed from all its near allies, inhabits West
+Africa.
+
+_Peculiarities of Generic, and Family Distribution._--The examples now
+given sufficiently illustrate the mode in which the several species of a
+genus are distributed. We have next to consider genera as the component
+parts of families, and families of orders, from the same point of view.
+{26}
+
+All the phenomena presented by the species of a genus are reproduced by the
+genera of a family, and often in a more marked degree. Owing, however, to
+the extreme restriction of genera by modern naturalists, there are not many
+among the higher animals that have a world-wide distribution. Among the
+mammalia there is no such thing as a truly cosmopolitan genus. This is
+owing to the absence of all the higher orders except the mice from
+Australia, while the genus Mus, which occurs there, is represented by a
+distinct group, Hesperomys, in America. If, however, we consider the
+Australian dingo as a native animal we might class the genus Canis as
+cosmopolite, but the wild dogs of South America are now formed into
+separate genera by some naturalists. Many genera, however, range over three
+or more continents, as Felis (the cat genus) absent only from Australia;
+Ursus (the bear genus) absent from Australia and tropical Africa; Cervus
+(the deer genus) with nearly the same range; and Sciurus (the squirrel
+genus) found in all the continents but Australia. Among birds Turdus, the
+thrush, and Hirundo, the swallow genus, are the only perching birds which
+are truly cosmopolites; but there are many genera of hawks, owls, wading
+and swimming birds, which have a world-wide range.
+
+As a great many genera consist of single species there is no lack of cases
+of great restriction, such as the curious lemur called the "potto," which
+is found only at Sierra Leone, and forms the genus Perodicticus; the true
+chinchillas found only in the Andes of Peru and Chili south of 9° S. lat.
+and between 8,000 and 12,000 feet elevation; several genera of finches each
+confined to limited portions of the higher Himalayas, the blood-pheasants
+(Ithaginis) found only above 10,000 feet from Nepal to East Thibet; the
+bald-headed starling of the Philippine islands, the lyre-birds of East
+Australia, and a host of others.
+
+It is among the different genera of the same family that we meet with the
+most striking examples of discontinuity, although these genera are often as
+unmistakably allied as are the species of a genus; and it is these cases
+that furnish the most interesting problems to the student of distribution.
+{27} We must therefore consider them somewhat more fully.
+
+Among mammalia the most remarkable of these divided families is that of the
+camels, of which one genus Camelus, the true camels, comprising the camel
+and dromedary, is confined to Asia, while the other Auchenia, comprising
+the llamas and alpacas, is found only in the high Andes and in the plains
+of temperate South America. Not only are these two genera separated by the
+Atlantic and by the greater part of the land of two continents, but one is
+confined to the Northern and the other to the Southern hemisphere. The next
+case, though not so well known, is equally remarkable; it is that of the
+Centetidæ, a family of small insectivorous animals, which are wholly
+confined to Madagascar and the large West Indian islands Cuba and Hayti,
+the former containing five genera and the latter a single genus with a
+species in each island. Here again we have the whole continent of Africa as
+well as the Atlantic ocean separating allied genera. Two families (or
+subfamilies) of rat-like animals, Octodontidæ and Echimyidæ, are also
+divided by the Atlantic. Both are mainly South American, but the former has
+two genera in North and East Africa, and the latter also two in South and
+West Africa. Two other families of mammalia, though confined to the Eastern
+hemisphere, are yet markedly discontinuous. The Tragulidæ are small
+deer-like animals, known as chevrotains or mouse-deer, abundant in India
+and the larger Malay islands and forming the genus Tragulus; while another
+genus, Hyomoschus, is confined to West Africa. The other family is the
+Simiidæ or anthropoid apes, in which we have the gorilla and chimpanzee
+confined to West and Central Africa, while the allied orangs are found only
+in the islands of Sumatra and Borneo, the two groups being separated by a
+greater space than the Echimyidæ and other rodents of Africa and South
+America.
+
+Among birds and reptiles we have several families, which, from being found
+only within the tropics of Asia, Africa, and America, have been termed
+tropicopolitan groups. The Megalæmidæ or barbets are gaily coloured {28}
+fruit-eating birds, almost equally abundant in tropical Asia and Africa,
+but less plentiful in America, where they probably suffer from the
+competition of the larger sized toucans. The genera of each country are
+distinct, but all are closely allied, the family being a very natural one.
+The trogons form a family of very gorgeously coloured and remarkable
+insect-eating birds very abundant in tropical America, less so in Asia, and
+with a single genus of two species in Africa.
+
+Among reptiles we have two families of snakes--the Dendrophidæ or
+tree-snakes, and the Dryiophidæ or green whip-snakes--which are also found
+in the three tropical regions of Asia, Africa, and America, but in these
+cases even some of the genera are common to Asia and Africa, or to Africa
+and America. The lizards forming the family Amphisbænidæ are divided
+between tropical Africa and America, a few species only occurring in the
+southern portion of the adjacent temperate regions; while even the
+peculiarly American family of the iguanas is represented by two genera in
+Madagascar, and one in the Fiji and Friendly Islands. Passing on to the
+Amphibians the worm-like Cæciliadæ are tropicopolitan, as are also the
+toads of the family Engystomatidæ. Insects also furnish some analogous
+cases, three genera of Cicindelidæ, (Pogonostoma, Ctenostoma, and
+Peridexia) showing a decided connection between this family in South
+America and Madagascar; while the beautiful family of diurnal moths,
+Uraniidæ, is confined to the same two countries. A somewhat similar but
+better known illustration is afforded by the two genera of ostriches, one
+confined to Africa and Arabia, the other to the plains of temperate South
+America.
+
+_General features of Overlapping and Discontinuous Areas._--These numerous
+examples of discontinuous genera and families form an important section of
+the facts of animal dispersal which any true theory must satisfactorily
+account for. In greater or less prominence they are to be found all over
+the world, and in every group of animals, and they grade imperceptibly into
+those cases of conterminous and overlapping areas which we have seen to
+{29} prevail in most extensive groups of species, and which are perhaps
+even more common in those large families which consist of many closely
+allied genera. A sufficient proof of the overlapping of generic areas is
+the occurrence of a number of genera of the same family together. Thus in
+France or Italy about twenty genera of warblers (Sylviadæ) are found, and
+as each of the thirty-three genera of this family inhabiting temperate
+Europe and Asia has a different area, a great number must here overlap. So,
+in most parts of Africa, at least ten or twelve genera of antelopes may be
+found, and in South America a large proportion of the genera of monkeys of
+the family Cebidæ occur in many districts; and still more is this the case
+with the larger bird families, such as the tanagers, the tyrant shrikes, or
+the tree-creepers, so that there is in all these extensive families no
+genus whose area does not overlap that of many others. Then among the
+moderately extensive families we find a few instances of one or two genera
+isolated from the rest, as the spectacled bear, Tremarctos, found only in
+Chili, while the remainder of the family extends from Europe and Asia over
+North America to the Mountains of Mexico, but no further south; the Bovidæ,
+or hollow-horned ruminants, which have a few isolated genera in the Rocky
+Mountains and the islands of Sumatra and Celebes; and from these we pass on
+to the cases of wide separation already given.
+
+_Restricted Areas of Families._--As families sometimes consist of single
+genera and even single species, they often present examples of very
+restricted range; but what is perhaps more interesting are those cases in
+which a family contains numerous species and sometimes even several genera,
+and yet is confined to a narrow area. Such are the golden moles
+(Chrysochloridæ) consisting of two genera and three species, confined to
+extratropical South Africa; the hill-tits (Liotrichidæ), a family of
+numerous genera and species mainly confined to the Himalayas, but with a
+few straggling species in the Malay countries and the mountains of China;
+the Pteroptochidæ, large wren-like birds, consisting of eight genera and
+nineteen species, almost entirely confined to temperate South America and
+{30} the Andes; and the birds-of-paradise, consisting of nineteen or twenty
+genera and about thirty-five species, almost all inhabitants of New Guinea
+and the immediately surrounding islands, while a few, doubtfully belonging
+to the family, extend to East Australia. Among reptiles the most striking
+case of restriction is that of the rough-tailed burrowing snakes
+(Uropeltidæ), the five genera and eighteen species being strictly confined
+to Ceylon and the southern parts of the Indian Peninsula.
+
+_The Distribution of Orders._--When we pass to the larger groups, termed
+orders, comprising several families, we find comparatively few cases of
+restriction and many of worldwide distribution; and the families of which
+they are composed are strictly comparable to the genera of which families
+are composed, inasmuch as they present examples of overlapping, or
+conterminous, or isolated areas, though the latter are comparatively rare.
+Among mammalia the Insectivora offer the best example of an order, several
+of whose families inhabit areas more or less isolated from the rest; while
+the Marsupialia have six families in Australia, and one, the opossums, far
+off in America.
+
+Perhaps, more important is the limitation of some entire orders to certain
+well-defined portions of the globe. Thus the Proboscidea, comprising the
+single family and genus of the elephants, and the Hyracoidea, that of the
+Hyrax or Syrian coney, are confined to parts of Africa and Asia; the
+Marsupials to Australia and America; and the Monotremata, the lowest of all
+mammals--comprising the duck-billed Platypus and the spiny Echidna, to
+Australia and New Guinea. Among birds the Struthiones or ostrich tribe are
+almost confined to the three Southern continents, South America, Africa and
+Australia; and among Amphibia the tailed Batrachia--the newts and
+salamanders--are similarly restricted to the northern hemisphere.
+
+These various facts will receive their explanation in a future chapter.
+
+ * * * * *
+
+
+[Illustration]
+
+{31}
+
+CHAPTER III
+
+CLASSIFICATION OF THE FACTS OF DISTRIBUTION.--ZOOLOGICAL REGIONS
+
+ The Geographical Divisions of the Globe do not correspond to Zoological
+ divisions--The range of British Mammals as indicating a Zoological
+ Region--Range of East Asian and North African Mammals--The Range of
+ British Birds--Range of East Asian Birds--The limits of the Palæarctic
+ Region--Characteristic features of the Palæarctic Region--Definition
+ and characteristic groups of the Ethiopian Region--Of the Oriental
+ Region--Of the Australian Region--Of the Nearctic Region--Of the
+ Neotropical Region--Comparison of Zoological Regions with the
+ Geographical Divisions of the Globe.
+
+Having now obtained some notion of how animals are dispersed over the
+earth's surface, whether as single species or as collected in those groups
+termed genera, families, and orders, it will be well, before proceeding
+further, to understand something of the classification of the facts we have
+been considering, and some of the simpler conclusions these facts lead to.
+
+We have hitherto described the distribution of species and groups of
+animals by means of the great geographical divisions of the globe in common
+use; but it will have been observed that in hardly any case do these define
+the limits of anything beyond species, and very seldom, or perhaps never,
+even those accurately. Thus the term "Europe" will not give, with any
+approach to accuracy, the range of any one genus of mammals or birds, and
+{32} perhaps not that of half-a-dozen species. Either they range into
+Siberia, or Asia Minor, or Palestine, or North Africa; and this seems to be
+always the case when their area of distribution occupies a large portion of
+Europe. There are, indeed, a few species limited to Central or Western or
+Southern Europe, and these are almost the only cases in which we can use
+the word for zoological purposes without having to add to it some portion
+of another continent. Still less useful is the term Asia for this purpose,
+since there is probably no single animal or group confined to Asia which is
+not also more or less nearly confined to the tropical or the temperate
+portion of it. The only exception is perhaps the tiger, which may really be
+called an Asiatic animal, as it occupies nearly two-thirds of the
+continent; but this is an unique example, while the cases in which Asiatic
+animals and groups are strictly limited to a portion of Asia, or extend
+also into Europe or into Africa or to the Malay Islands, are exceedingly
+numerous. So, in Africa, very few groups of animals range over the whole of
+it without going beyond either into Europe or Asia Minor or Arabia, while
+those which are purely African are generally confined to the portion south
+of the tropic of Cancer. Australia and America are terms which better serve
+the purpose of the zoologist. The former defines the limit of many
+important groups of animals; and the same may be said of the latter, but
+the division into North and South America introduces difficulties, for
+almost all the groups especially characteristic of South America are found
+also beyond the isthmus of Panama, in what is geographically part of the
+northern continent.
+
+It being thus clear that the old and popular divisions of the globe are
+very inconvenient when used to describe the range of animals, we are
+naturally led to ask whether any other division can be made which will be
+more useful, and will serve to group together a considerable number of the
+facts we have to deal with. Such a division was made by Mr. P. L. Sclater
+more than twenty years ago, and it has, with some slight modifications,
+come into pretty general use in this country, and to some extent also {33}
+abroad; we shall therefore proceed to explain its nature and the principles
+on which it is established, as it will have to be often referred to in
+future chapters of this work, and will take the place of the old
+geographical divisions whose inconvenience has already been pointed out.
+The primary zoological divisions of the globe are called "regions," and we
+will begin by ascertaining the limits of the region of which our own
+country forms a part.
+
+_The Range of British Mammals as indicating a Zoological Region._--We will
+first take our commonest wild mammalia and see how far they extend, and
+especially whether they are confined to Europe or range over parts of other
+continents:
+
+ 1. Wild Cat | Europe | N. Africa | Siberia, Afghanistan.
+ 2. Fox | Europe | N. Africa | Central Asia to Amoor.
+ 3. Weasel | Europe | N. Africa | Central Asia to Amoor.
+ 4. Otter | Europe | N. Africa | Siberia.
+ 5. Badger | Europe | N. Africa | Central Asia to Amoor.
+ 6. Stag | Europe | N. Africa | Central Asia to Amoor.
+ 7. Hedgehog | Europe | -- | Central Asia to Amoor.
+ 8. Mole | Europe | -- | Central Asia.
+ 9. Squirrel | Europe | -- | Central Asia to Amoor.
+ 10. Dormouse | Europe | -- | --
+ 11. Water-rat | Europe | -- | Central Asia to Amoor.
+ 12. Hare | Europe | -- | W. Siberia, Persia.
+ 13. Rabbit | Europe | N. Africa | --
+
+We thus see that out of thirteen of our commonest quadrupeds only one is
+confined to Europe, while seven are found also in Northern Africa, and
+eleven range into Siberia, most of them stretching quite across Asia to the
+valley of the Amoor on the extreme eastern side of that continent. Two of
+the above-named British species, the fox and weasel, are also inhabitants
+of the New World, being as common in the northern parts of North America as
+they are with us; but with these exceptions the entire range of our
+commoner species is given, and they clearly show that all Northern Asia and
+Northern Africa must be added to Europe in order to form the region which
+they collectively inhabit. If now we go into Central Europe and take, for
+example, the quadrupeds of Germany, we shall find that these too, although
+much more numerous, are confined to the same limits, except that some of
+the {34} more arctic kinds, as already stated, extend into the colder
+regions of North America.
+
+_Range of East Asian and North African Mammals._--Let us now pass to the
+other side of the great northern continent, and examine the list of the
+quadrupeds of Amoorland, in the same latitude as Germany. We find that
+there are forty-four terrestrial species (omitting the bats, the seals, and
+other marine animals), and of these no less than twenty-six are identical
+with European species, and twelve or thirteen more are closely allied
+representatives, leaving only five or six which are peculiarly Asiatic. We
+can hardly have a more convincing proof of the essential oneness of the
+mammalia of Europe and Northern Asia.
+
+In Northern Africa we do not find so many European species (though even
+here they are very numerous) because a considerable number of West Asiatic
+and desert forms occur. Having, however, shown that Europe and Western Asia
+have almost identical animals, we may treat all these as really European,
+and we shall then be able to compare the quadrupeds of North Africa with
+those of Europe and West Asia. Taking those of Algeria as the best known,
+we find that there are thirty-three species identical with those of Europe
+and West Asia, while twenty-four more, though distinct, are closely allied,
+belonging to the same genera; thus making a total of fifty-seven of
+European type. On the other hand, we have seven species which are either
+identical with species of tropical Africa or allied to them, and six more
+which are especially characteristic of the African and Asiatic deserts
+which form a kind of neutral zone between the temperate and tropical
+regions. If now we consider that Algeria and the adjacent countries
+bordering the Mediterranean form part of Africa, while they are separated
+from Europe by a wide sea and are only connected with Asia by a narrow
+isthmus, we cannot but feel surprised at the wonderful preponderance of the
+European and West Asiatic elements in the mammalia which inhabit the
+district.
+
+_The Range of British Birds._--As it is very important that no doubt should
+exist as to the limits of the zoological {35} region of which Europe forms
+a part, we will now examine the birds, in order to see how far they agree
+in their distribution with the mammalia. Of late years great attention has
+been paid to the distribution of European and Asiatic birds, many
+ornithologists having travelled in North Africa, in Palestine, in Asia
+Minor, in Persia, in Siberia, in Mongolia, and in China; so that we are now
+able to determine the exact ranges of many species in a manner that would
+have been impossible a few years ago. These ranges are given for all
+British species in the new edition of Yarrell's _History of British Birds_
+edited by Professor Newton, while those of all European birds are given in
+still more detail in Mr. Dresser's beautiful work on the birds of Europe.
+In order to confine our examination within reasonable limits, and at the
+same time give it the interest attaching to familiar objects, we will take
+the whole series of British Passeres or perching birds given in Professor
+Newton's work (118 in number) and arrange them in series according to the
+extent of their range. These include not only the permanent residents and
+regular migrants to our country, but also those which occasionally straggle
+here, so that it really comprises a large proportion of all European birds.
+
+I. BRITISH BIRDS WHICH EXTEND TO NORTH AFRICA AND CENTRAL OR NORTH-EAST
+ASIA.
+
+ 1. _Lanius collurio_ Red backed Shrike (also all Africa).
+ 2. _Oriolus Galbula_ Golden Oriole (also all Africa).
+ 3. _Turdus musicus_ Song-Thrush.
+ 4. ,, _iliacus_ Red-wing.
+ 5. ,, _pilaris_ Fieldfare.
+ 6. _Monticola saxatilis_ Blue rock Thrush.
+ 7. _Ruticilla suecica_ Bluethroat (also India in winter).
+ 8. _Saxicola rubicola_ Stonechat (also India in winter).
+ 9. ,, _oenanthe_ Wheatear (also N. America).
+ 10. _Acrocephalus arundinaceus_ Great Reed-Warbler.
+ 11. _Sylvia curruca_ Lesser Whitethroat.
+ 12. _Parus major_ Great Titmouse.
+ 13. _Motacilla sulphurea_ Grey Wagtail (also China and Malaya).
+ 14. ,, _raii_ Yellow Wagtail.
+ 15. _Anthus trivialis_ Tree Pipit.
+ 16. ,, _spiloletta_ Water Pipit.
+ 17. ,, _campestris_ Tawny Pipit.
+ 18. _Alauda arvensis_ Skylark.
+ 19. ,, _cristata_ Crested Lark.
+ {36}
+ 20. _Emberiza schoeniclus_ Reed Bunting.
+ 21. ,, _citrinella_ Yellow-hammer.
+ 22. _Fringilla montifringilla_ Brambling.
+ 23. _Passer montanus_ Tree Sparrow (also S. Asia).
+ 24. ,, _domesticus_ House Sparrow.
+ 25. _Coccothraustes vulgaris_ Hawfinch.
+ 26. _Carduelis spinus_ Siskin (also China).
+ 27. _Loxia curvirostra_ Crossbill.
+ 28. _Sturnus vulgaris_ Starling.
+ 29. _Pyrrhocorax graculus_ Chough.
+ 30. _Corvus corone_ Crow.
+ 31. _Hirundo rustica_ Swallow (all Africa and Asia).
+ 32. _Cotyle riparia_ Sand Martin (also India and N. America).
+
+II. BRITISH BIRDS WHICH RANGE TO CENTRAL OR NORTH-EAST ASIA.
+
+ 1. _Lanius excubitor_ Great Grey Shrike.
+ 2. _Turdus varius_ White's Thrush (also to Japan).
+ 3. ,, _atrigularis_ Black-throated Thrush.
+ 4. _Acrocephalus nævius_ Grasshopper Warbler.
+ 5. _Phylloscopus superciliosus_ Yellow-browed Warbler.
+ 6. _Certhia familiaris_ Tree-creeper.
+ 7. _Parus coeruleus_ Blue Titmouse.
+ 8. ,, _ater_ Coal Titmouse.
+ 9. ,, _palustris_ Marsh Titmouse.
+ 10. _Acredula caudata_ Long-tailed Titmouse.
+ 11. _Ampelis garrulus_ Wax-wing.
+ 12. _Anthus richardi_ Richard's Pipit.
+ 13. _Alauda alpestris_ Shore Lark (also N. America).
+ 14. _Plectrophanes nivalis_ Snow-Bunting (also N. America).
+ 15. ,, _lapponicus_ Lapland Bunting.
+ 16. _Emberiza rustica_ Rustic Bunting (also China).
+ 17. ,, _pusilla_ Little Bunting.
+ 18. _Linota linaria_ Mealy Redpole (also N. America).
+ 19. _Pyrrhula erythrina_ Scarlet Grosbeak (also N. India, China).
+ 20. ,, _enucleator_ Pine Grosbeak (also N. America).
+ 21. _Loxia bifasciata_ Two-barred Crossbill.
+ 22. _Pastor roseus_ Rose-coloured Starling (also India).
+ 23. _Corvus corax_ Raven (also N. America).
+ 24. _Pica rustica_ Magpie.
+ 25. _Nucifraga caryocatactes_ Nutcracker.
+
+III. BRITISH BIRDS RANGING INTO N. AFRICA AND W. ASIA.
+
+ 1. _Lanius minor_ Lesser Grey Shrike.
+ 2. ,, _auriculatus_ Woodchat (also Tropical Africa).
+ 3. _Muscicapa grisola_ Spotted Flycatcher (also E. and S.
+ Africa).
+ 4. ,, _atricapilla_ Pied Flycatcher (also Central Africa).
+ 5. Turdus _viscivorus_ Mistletoe-Thrush (N. India in winter).
+ 6. ,, _merula_ Blackbird.
+ 7. ,, _torquatus_ Ring Ouzel.
+ 8. _Accentor modularis_ Hedge Sparrow.
+ 9. _Erithacus rubecula_ Redbreast.
+ 10. _Daulias luscinia_ Nightingale.
+ {37}
+ 11. _Ruticilla phænicurus_ Redstart.
+ 12. ,, _tithys_ Black Redstart.
+ 13. _Saxicola rubetra_ Whinchat.
+ 14. _Aëdon galactodes_ Rufous Warbler.
+ 15. _Acrocephalus streperus_ Reed Warbler.
+ 16. ,, _schænobenus_ Sedge Warbler.
+ 17. _Melizophilus undatus_ Dartford Warbler.
+ 18. _Sylvia rufa_ Greater Whitethroat.
+ 19. ,, _salicaria_ Garden Warbler.
+ 20. ,, _atricapilla_ Blackcap.
+ 21. ,, _orphea_ Orphean Warbler.
+ 22. _Phylloscopus sibilatrix_ Wood Wren.
+ 23. ,, _trochilus_ Willow Wren.
+ 24. ,, _collybita_ Chiffchaff.
+ 25. _Regulus cristatus_ Golden-crested Wren.
+ 26. ,, _ignicapillus_ Fire-crested Wren.
+ 27. _Troglodytes parvulus_ Wren.
+ 28. _Sitta cæsia_ Nuthatch.
+ 29. _Motacilla alba_ White Wagtail (also W. Africa).
+ 30. ,, _flava_ Blue-headed Wagtail.
+ 31. _Anthus pratensis_ Meadow-Pipit.
+ 32. _Alauda arborea_ Woodlark.
+ 33. _Calandrella brachydactyla_ Short-toed Lark.
+ 34. _Emberiza miliaria_ Common Bunting.
+ 35. ,, _cirlus_ Cirl Bunting.
+ 36. ,, _hortulana_ Ortolan.
+ 37. _Fringilla coelebs_ Chaffinch.
+ 38. _Coccothraustes chloris_ Greenfinch.
+ 39. _Serinus hortulanus_ Serin.
+ 40. _Carduelis elegans_ Goldfinch.
+ 41. _Linota cannabina_ Linnet.
+ 42. _Corvus monedula_ Jackdaw.
+ 43. _Chelidon urbica_ House-Martin.
+
+IV. BRITISH BIRDS RANGING TO NORTH AFRICA.
+
+ 1. _Hypolais icterina_ Icterine Warbler.
+ 2. _Acrocephalus aquaticus_ Aquatic Warbler.
+ 3. ,, _luscinioides_ Savi's Warbler.
+ 4. _Motacilla lugubris_ Pied Wagtail.
+ 5. _Pyrrhula europæa_ Bullfinch.
+ 6. _Garrulus glandarius_ Jay.
+
+V. BRITISH BIRDS RANGING TO WEST ASIA ONLY.
+
+ 1. _Accentor collaris_ Alpine Accentor.
+ 2. _Muscicapa parva_ Red-breasted Flycatcher (to N. W.
+ India).
+ 3. _Panurus biarmicus_ Bearded Titmouse.
+ 4. _Melanocorypha sibirica_ White-winged Lark.
+ 5. _Euspiza melanocephala_ Black-headed Bunting.
+ 6. _Linota flavirostris_ Twite.
+ 7. _Corvus frugilegus_ Rook.
+
+VI. BRITISH BIRDS CONFINED TO EUROPE.
+
+ 1. _Cinclus aquaticus_ Dipper (closely allied races inhabit
+ other parts of the Palæarctic Region).
+ 2. _Parus cristatus_ Crested Titmouse.
+ {38}
+ 3. _Anthus obscurus_ Rock Pipit.
+ 4. _Linota rufescens_ Lesser Redpoll (closely allied races in
+ N. Asia and N. America).
+ 5. _Loxia pityopsittacus_ Parrot Crossbill (a closely allied form
+ in N. Asia).
+
+We find, that out of a total of 118 British Passeres there are:
+
+ 32 species which range to North Africa and Central or East Asia.
+
+ 25 species which range to Central or East Asia, but not to North
+ Africa.
+
+ 43 species which range to North Africa and Western Asia.
+
+ 6 species which range to North Africa, but not at all into Asia.
+
+ 7 species which range to West Asia, but not to North Africa.
+
+ 5 species which do not range out of Europe.
+
+These figures agree essentially with those furnished by the mammalia, and
+complete the demonstration that all the temperate portions of Asia and
+North Africa must be added to Europe to form a natural zoological division
+of the earth. We must also note how comparatively few of these overpass the
+limits thus indicated; only seven species extending their range
+occasionally into tropical or South Africa, eight into some parts of
+tropical Asia, and six into arctic or temperate North America.
+
+_Range of East Asian Birds._--To complete the evidence we only require to
+know that the East Asiatic birds are as much like those of Europe, as we
+have already shown to be the case when we take the point of departure from
+our end of the continent. This does not follow necessarily, because it is
+possible that a totally distinct North Asiatic fauna might there prevail;
+and, although our birds go eastward to the remotest parts of Asia, their
+birds might not come westward to Europe. The birds of Eastern Siberia have
+been carefully studied by Russian naturalists and afford us the means of
+making the required comparison. There are 151 species belonging to the
+orders Passeres and Picariæ (the perching and climbing birds), and of these
+no less than 77, or more than half, are absolutely identical {39} with
+European species; 63 are peculiar to North Asia, but all except five or six
+of these are allied to European forms; the remaining 11 species are
+migrants from South-eastern Asia. The resemblance is therefore equally
+close whichever extremity of the Euro-Asiatic continent we take as our
+starting point, and is equally remarkable in birds as in mammalia. We have
+now only to determine the limits of this, our first zoological region,
+which has been termed the "Palæarctic" by Mr. Sclater, meaning the
+"northern old-world" region--a name now well known to naturalists.
+
+_The Limits of the Palæarctic Region._--The boundaries of this region, as
+nearly as they can be ascertained, are shown on our general map at the
+beginning of this chapter, but it will be evident on consideration, that,
+except in a few places, its limits can only be approximately defined. On
+the north, east, and west it extends to the ocean, and includes a number of
+islands whose peculiarities will be pointed out in a subsequent chapter; so
+that the southern boundary alone remains, but as this runs across the
+entire continent from the Atlantic to the Pacific ocean, often traversing
+little-known regions, we may perhaps never be able to determine it
+accurately, even if it admits of such determination. In drawing the
+boundary line across Africa we meet with our first difficulty. The
+Euro-Asiatic animals undoubtedly extend to the northern borders of the
+Sahara, while those of tropical Africa come up to its southern margin, the
+desert itself forming a kind of sandy ocean between them. Some of the
+species on either side penetrate and even cross the desert, but it is
+impossible to balance these with any accuracy, and it has therefore been
+thought best, as a mere matter of convenience, to consider the geographical
+line of the tropic of Cancer to form the boundary. We are thus enabled to
+define the Palæarctic region as including all north temperate Africa; and,
+a similar intermingling of animal types occurring in Arabia, the same
+boundary line is continued to the southern shore of the Persian Gulf.
+Persia and Afghanistan undoubtedly belong to the Palæarctic region, and
+Baluchistan should probably go with these. The boundary in the
+north-western part of India is again difficult to determine, but it {40}
+cannot be far one way or the other from the river Indus as far up as
+Attock, opposite the mouth of the Cabool river. Here it will bend to the
+south-east, passing a little south of Cashmeer, and along the southern
+slopes of the Himalayas into East Thibet and China, at heights varying from
+9,000 to 11,000 feet according to soil, aspect, and shelter. It may,
+perhaps, be defined as extending to the upper belt of forests as far as
+coniferous trees prevail; but the temperate and tropical faunas are here so
+intermingled that to draw any exact parting line is impossible. The two
+faunas are, however, very distinct. In and above the pine woods there are
+abundance of warblers of northern genera, with wrens, numerous titmice, and
+a great variety of buntings, grosbeaks, bullfinches and rosefinches, all
+more or less nearly allied to the birds of Europe and Northern Asia; while
+a little lower down we meet with a host of peculiar birds allied to those
+of tropical Asia and the Malay Islands, but often of distinct genera. There
+can be no doubt, therefore, of the existence here of a pretty sharp line of
+demarkation between the temperate and tropical faunas, though this line
+will be so irregular, owing to the complex system of valleys and ridges,
+that in our present ignorance of much of the country it cannot be marked in
+detail on any map.
+
+Further east in China it is still more difficult to determine the limits of
+the region, owing to the great intermixture of migrating birds; tropical
+forms passing northwards in summer as far as the Amoor river, while the
+northern forms visit every part of China in winter. From what we know,
+however, of the distribution of some of the more typical northern and
+southern species, we are able to fix the limits of the Palæarctic region a
+little south of Shanghai on the east coast. Several tropical genera come as
+far north as Ningpo or even Shanghai, but rarely beyond; while in Formosa
+and Amoy tropical forms predominate. Such decidedly northern forms as
+bullfinches and hawfinches are found at Shanghai; hence we may commence the
+boundary line on the coast between Shanghai and Ningpo, but inland it
+probably bends a little southward, and then northward to the mountains and
+valleys of West {41} China and East Thibet in about 32° N. latitude; where,
+at Moupin, a French missionary, Père David, made extensive collections
+showing this district to be at the junction of the tropical and temperate
+faunas. Japan, as a whole, is decidedly Palæarctic, although its extreme
+southern portion, owing to its mild insular climate and evergreen
+vegetation, gives shelter to a number of tropical forms.
+
+_Characteristic Features of the Palæarctic Region._--Having thus
+demonstrated the unity of the Palæarctic region by tracing out the
+distribution of a large proportion of its mammalia and birds, it only
+remains to show how far it is characterised by peculiar groups such as
+genera and families, and to say a few words on the lower forms of life
+which prevail in it.
+
+Taking first the mammalia, we find this region distinguished by possessing
+two peculiar genera of Talpidæ or moles, the family being confined to the
+Palæarctic and Nearctic regions. The true hedgehogs (Erinaceus) are also
+characteristic, being only found elsewhere in South Africa and in the
+northern part of the Oriental region. Among Carnivora, the racoon-dog
+(Nyctereutes) of North-eastern Asia, and the true badgers of the genus
+Meles are peculiar, most other parts of the world possessing distinct
+genera of badgers. It has six peculiar genera, or subgenera, of deer; seven
+peculiar genera of Bovidæ, chiefly antelopes; while the entire group of
+goats and sheep, comprising twenty-two species, is almost confined to it,
+one species only occurring in the Rocky mountains of North America and
+another in the Nilgiris of Southern India. Among the rodents there are nine
+genera with twenty-seven species wholly confined to it, while several
+others, as the hamsters, the dormice, and the pikas, have only a few
+species elsewhere.
+
+In birds there are a large number of peculiar genera of which we need
+mention only a few of the more important, as the grass-hopper warblers
+(Locustella) with seven species, the Accentors with twelve species, and
+about a dozen other genera of warblers, including the robins; the bearded
+titmouse and several allied genera; the long-tailed titmice forming the
+genus Acredula; the magpies, choughs, and nut-crackers; a host of finches,
+among which the bullfinches (Pyrrhula) and the buntings (Emberiza) are the
+{42} most important. The true pheasants (Phasianus) are wholly Palæarctic,
+except one species in Formosa, as are several genera of wading birds.
+Though the reptiles of cold countries are few as compared with those of the
+tropics, the Palæarctic region in its warmer portions has a considerable
+number, and among these are many which are peculiar to it. Such are four
+genera of snakes, seven of lizards, five of frogs and toads, and twelve of
+newts and salamanders; while of fresh-water fishes there are about twenty
+peculiar genera.[7] Among insects we may mention the elegant Apollo
+butterflies of the Alps as forming a peculiar genus (Parnassius), only
+found elsewhere in the Rocky Mountains of North America, while the
+beautiful genus Thais of the south of Europe and Sericinus of North China
+are equally remarkable. Among other insects we can only now refer to the
+great family of Carabidæ, or predaceous ground-beetles, which are immensely
+numerous in this region, there being about fifty peculiar genera; while the
+large and handsome genus Carabus, with its allies Procerus and Procrustes,
+containing nearly 300 species, is almost wholly confined to this region,
+and would alone serve to distinguish it zoologically from all other parts
+of the globe.
+
+{43}
+
+Having given so full an exposition of the facts which determine the extent
+and boundaries of the Palæarctic region, there is less need of entering
+into much detail as regards the other regions of the Eastern Hemisphere;
+their boundaries being easily defined, while their forms of animal life are
+well marked and strongly contrasted.
+
+_Definition and Characteristic Groups of the Ethiopian Region._--The
+Ethiopian region consists of all tropical and south Africa, to which are
+appended the large island of Madagascar and the Mascarene Islands to the
+east and north of it, though these differ materially from the continent,
+and will have to be discussed in a separate chapter. For the present, then,
+we will take Africa south of the tropic of Cancer, and consider how far its
+animals are distinct from those of the Palæarctic region.
+
+Taking first the mammalia, we find the following remarkable animals at once
+separating it from the Palæarctic and every other region. The gorilla and
+chimpanzee, the baboons, numerous lemurs, the spotted hyæna, the aard-wolf
+and hyæna-dog, zebras, the hippopotamus, giraffe, and more than seventy
+peculiar antelopes. Here we have a wonderful collection of large and
+peculiar quadrupeds, but the Ethiopian region is also characterised by the
+absence of others which are not only abundant in the Palæarctic region but
+in many tropical regions as well. The most remarkable of these deficiencies
+are the bears the deer and the wild oxen, all of which abound in the
+tropical parts of Asia while bears and deer extend into both North and
+South America. Besides the large and conspicuous animals mentioned above,
+Africa possesses a number of completely isolated groups; such are the
+potamogale, a curious otter-like water-shrew, discovered by Du Chaillu in
+West Africa, so distinct as to constitute a new family, Potamogalidæ; the
+goldenmoles, also forming a peculiar family, Chrysochloridæ; as do the
+elephant-shrews, Macroscelididæ; the singular aard-varks, or earth-pigs,
+forming a peculiar family of Edentata called Orycteropodidæ; while there
+are numerous peculiar genera of monkeys, swine, civets, and rodents.
+
+Among birds the most conspicuous and remarkable are, the great-billed
+vulture-crows (Corvultur), the long-tailed {44} whydah finches (Vidua), the
+curious ox-peckers (Buphaga), the splendid metallic starlings
+(Lamprocolius), the handsome plantain-eaters (Musophaga), the
+ground-hornbills (Bucorvus), the numerous guinea-fowls belonging to four
+distinct genera, the serpent-eating secretary-bird (Serpentarius), the huge
+boat-billed heron (Balæniceps), and the true ostriches. There are also
+three quite peculiar African families, the Musophagidæ or plantain-eaters,
+including the elegant crested touracos; the curious little finch-like
+colies (Coliidæ), and the Irrisoridæ, insect-eating birds allied to the
+hoopoes but with glossy metallic plumage and arboreal habits.
+
+In reptiles, fishes, insects, and land-shells, Africa is very rich, and
+possesses an immense number of peculiar forms. These are not sufficiently
+familiar to require notice in a work of this character, but we may mention
+a few as mere illustrations: the puff-adders, the most hideous of poisonous
+snakes; the chameleons, the most remarkable of lizards; the
+goliath-beetles, the largest and handsomest of the Cetoniidæ; and some of
+the Achatinæ, which are the largest of all known land-shells.
+
+_Definition and Characteristic Groups of the Oriental Region._--The
+Oriental region comprises all Asia south of the Palæarctic limits, and
+along with this the Malay Islands as far as the Philippines, Borneo, and
+Java. It was called the Indian region by Mr. Sclater, but this term has
+been objected to because the Indo-Chinese and Malayan districts are the
+richest and most characteristic, while the peninsula of India is the
+poorest portion of it. The name "Oriental" has therefore been adopted in my
+work on _The Geographical Distribution of Animals_ as preferable to either
+Malayan or Indo-Australian, both of which have been proposed, but are
+objectionable, as being already in use in a different sense.
+
+The great features of the mammals of the Oriental region are, the
+long-armed apes, the orang-utans, the tiger, the sun-bears and honey-bears,
+the tapir, the chevrotains or mouse-deer, and the Indian elephant. Its most
+conspicuous birds are the immense number and variety of babbling-thrushes
+(Timaliidæ), its beautiful little hill-tits (Liotrichidæ), its green
+bulbuls (Phyllornithidæ), its many varieties {45} of the crow-family, its
+beautiful gapers and pittas adorned with the most delicate colours, its
+great variety of hornbills, and its magnificent Phasianidæ, comprising the
+peacocks, argus-pheasants, fire-backed pheasants, and jungle-fowl. Many of
+these are, it is true, absent from the peninsula of Hindostan, but
+sufficient remain there to ally it with the other parts of the region.
+
+Among the remarkable but less conspicuous forms of mammalia which are
+peculiar to this region are, monkeys of the genus Presbyter, extending to
+every part of it; lemurs of three peculiar genera--Nycticebus and Loris
+(slow lemurs) and Tarsius (spectre lemurs); the flying lemur
+(Galeopithecus), now classed as a peculiar family of Insectivora and found
+only in the Malay Islands; the family of the Tupaias, or squirrel-shrews,
+curious little arboreal Insectivora somewhat resembling squirrels; no less
+than twelve peculiar genera of the civet family, three peculiar antelopes,
+five species of rhinoceros, and the round-tailed flying squirrels forming
+the genus Pteromys.
+
+Of the peculiar groups of birds we can only mention a few. The curious
+little tailor-birds of the genus Orthotomus are found over the whole region
+and almost alone serve to characterise it, as do the fine
+laughing-thrushes, forming the genus Garrulax; while the beautiful
+grass-green fruit-thrushes (Phyllornis), and the brilliant little minivets
+(Pericrocotus), are almost equally universal. Woodpeckers are abundant,
+belonging to a dozen peculiar genera; while gaudy barbets and strange forms
+of cuckoos and hornbills are also to be met with everywhere. Among game
+birds, the only genus that is universally distributed, and which may be
+said to characterise the region, is Gallus, comprising the true
+jungle-fowl, one of which, Gallus bankiva, is found from the Himalayas and
+Central India to Malacca, Java, and even eastward to Timor, and is the
+undoubted origin of almost all our domestic poultry. Southern India and
+Ceylon each possesses distinct species of jungle-fowl, and a third very
+handsome green bird (Gallus æneus inhabits Java.)
+
+Reptiles are as abundant as in Africa, but they present no well-known
+groups which can be considered as specially characteristic. Among insects
+we may notice the {46} magnificent golden and green Papilionidæ of various
+genera as being unequalled in the world; while the great Atlas moth is
+probably the most gigantic of Lepidoptera, being sometimes ten inches
+across the wings, which are also very broad. Among the beetles the strange
+flat-bodied Malayan mormolyce is the largest of all the Carabidæ, while the
+catoxantha is equally a giant among the Buprestidæ. On the whole, the
+insects of this region probably surpass those of any other part of the
+world, except South America, in size, variety, and beauty.
+
+_Definition and Characteristic Groups of the Australian Region._--The
+Australian region is so well marked off from the Oriental, as well as from
+all other parts of the world, by zoological peculiarities, that we need not
+take up much time in describing it, especially as some of its component
+islands will come under review at a subsequent stage of our work. Its most
+important portions are Australia and New Guinea, but it also includes all
+the Malayan and Pacific Islands to the east of Borneo, Java, and Bali, the
+Oriental region terminating with the submarine bank on which those islands
+are situated. The island of Celebes is included in this region from a
+balance of considerations, but it almost equally well belongs to the
+Oriental, and must be left out of the account in our general sketch of the
+zoological features of the Australian region.
+
+The great feature of the Australian region is the almost total absence of
+all the forms of terrestrial mammalia which abound in the rest of the
+world, their place being supplied by a great variety of Marsupials. In
+Australia and New Guinea there are no Insectivora, Carnivora, nor Ungulata,
+while even the rodents are only represented by a few small rats and mice.
+In the remoter Pacific Islands mammals are altogether absent (except
+perhaps in New Zealand), but in the Moluccas and other islands bordering on
+the Oriental region the higher mammals are represented by a few deer,
+civets, and pigs, though it is doubtful whether the two former may not have
+been introduced by man, as was almost certainly the case with the
+semi-domesticated dingo of Australia.[8] These peculiarities in the
+mammalia {47} are so great that every naturalist agrees that Australia must
+be made a separate region, the only difference of opinion being as to its
+extent, some thinking that New Zealand should form another separate region;
+but this question need not now delay us.
+
+In birds Australia is by no means so isolated from the rest of the world,
+as it contains great numbers of warblers, thrushes, flycatchers, shrikes,
+crows, and other familiar types of the Eastern Hemisphere; yet a
+considerable number of the most characteristic Oriental families are
+absent. Thus there are no vultures, woodpeckers, pheasants, bulbuls, or
+barbets in the Australian region; and the absence of these is almost as
+marked a feature as that of cats, deer, or monkeys, among mammalia. The
+most conspicuous and characteristic birds of the Australian region are, the
+piping crows; the honey-suckers (Meliphagidæ), a family quite peculiar to
+the region; the lyre-birds; the great terrestrial kingfishers (Dacelo); the
+great goat-suckers called more-porks in Australia and forming the genus
+Podargus; the wonderful abundance of parrots, including such remarkable
+forms as the white and black cockatoos, and the gorgeously coloured
+brush-tongued lories; the almost equal abundance of fine pigeons more gaily
+coloured than any others on the globe; the strange brush-turkeys and
+mound-builders, the only birds that {48} never sit upon their eggs, but
+allow them to be hatched, reptile-like, by the heat of the sand or of
+fermenting vegetable matter; and lastly, the emus and cassowaries, in which
+the wings are far more rudimentary than in the ostriches of Africa and
+South America. New Guinea and the surrounding islands are remarkable for
+their tree-kangaroos, their birds-of-paradise, their raquet-tailed
+kingfishers, their great crown-pigeons, their crimson lories, and many
+other remarkable birds. This brief outline being sufficient to show the
+distinctness and isolation of the Australian region, we will now pass to
+the consideration of the Western Hemisphere.
+
+_Definition and Characteristic Groups of the Nearctic Region._--The
+Nearctic region comprises all temperate and arctic North America, including
+Greenland, the only doubt being as to its southern boundary, many northern
+types penetrating into the tropical zone by means of the highlands and
+volcanic peaks of Mexico and Guatemala, while a few which are
+characteristic of the tropics extend northward into Texas and California.
+There is, however, considerable evidence showing that on the east coast the
+Rio Grande del Norte, and on the west a point nearly opposite Cape St.
+Lucas, form the most natural boundary; but instead of being drawn straight
+across, the line bends to the south-east as soon as it rises on the flanks
+of the table-land, forming a deep loop which extends some distance beyond
+the city of Mexico, and perhaps ought to be continued along the higher
+ridges of Guatemala.
+
+The Nearctic region is so similar to the Palæarctic in position and
+climate, and the two so closely approach each other at Behring Straits,
+that we cannot wonder at there being a certain amount of similarity between
+them--a similarity which some naturalists have so far over-estimated as to
+think that the two regions ought to be united. Let us therefore carefully
+examine the special zoological features of this region, and see how far it
+resembles, and how far differs from, the Palæarctic.
+
+At first sight the mammalia of North America do not seem to differ much
+from those of Europe or Northern Asia. There are cats, lynxes, wolves and
+foxes, weasels, bears, elk and deer, voles, beavers, squirrels, marmots,
+and {49} hares, all very similar to those of the Eastern Hemisphere, and
+several hardly distinguishable. Even the bison or "buffalo" of the
+prairies, once so abundant and characteristic, is a close ally of the now
+almost extinct "aurochs" of Lithuania. Here, then, we undoubtedly find a
+very close resemblance between the two regions, and if this were all, we
+should have great difficulty in separating them. But along with these, we
+find another set of mammals, not quite so conspicuous but nevertheless very
+important. We have first, three peculiar genera of moles, one of which, the
+star-nosed mole, is a most extraordinary creature, quite unlike anything
+else. Then there are three genera of the weasel family, including the
+well-known skunk (Mephitis), all quite different from Eastern forms. Then
+we come to a peculiar family of carnivora, the racoons, very distinct from
+anything in Europe or Asia; and in the Rocky Mountains we find the
+prong-horn antelope (Antilocapra) and the mountain goat of the trappers
+(Aplocerus), both peculiar genera. Coming to the rodents we find that the
+mice of America differ in some dental peculiarities from those of the rest
+of the world, and thus form several distinct genera; the jumping mouse
+(Xapus) is a peculiar form of the jerboa family, and then we come to the
+pouched rats (Geomyidæ), a very curious family consisting of four genera
+and nineteen species, peculiar to North America, though not confined to the
+Nearctic region. The prairie dogs (Cynomys), the tree porcupine
+(Erethizon), the curious sewellel (Haploodon), and the opossum (Didelphys)
+complete the list of peculiar mammalia which distinguish the northern
+region of the new world from that of the old. We must add to these
+peculiarities some remarkable deficiencies. The Nearctic region has no
+hedgehogs, nor wild pigs, nor dormice, and only one wild sheep in the Rocky
+Mountains as against twenty species of sheep and goats in the Palæarctic
+region.
+
+In birds also the similarities to our own familiar songsters first strike
+us, though the differences are perhaps really greater than in the
+quadrupeds. We see thrushes and wrens, tits and finches, and what seem to
+be warblers and flycatchers and starlings in abundance; but a closer
+examination shows the ornithologist that what he took for the {50} latter
+are really quite distinct, and that there is not a single true flycatcher
+of the family Muscicapidæ, or a single starling of the family Sturnidæ in
+the whole continent, while there are very few true warblers (Sylviidæ),
+their place being taken by the quite distinct families Mniotiltidæ or
+wood-warblers, and Vireonidæ or greenlets. In like manner the flycatchers
+of America belong to the totally distinct family of tyrant-birds,
+Tyrannidæ, and those that look like starlings to the hang-nests, Icteridæ;
+and these four peculiar families comprise about a hundred and twenty
+species, and give a special character to the ornithology of the country.
+Add to these such peculiar birds as the mocking thrushes (Mimus), the blue
+jays (Cyanocitta), the tanagers, the peculiar genera of cuckoos (Coccygus
+and Crotophaga), the humming-birds, the wild turkeys (Meleagris), and the
+turkey-buzzards (Cathartes), and we see that if there is any doubt as to
+the mammals of North America being sufficiently distinct to justify the
+creation of a separate region, the evidence of the birds would alone settle
+the question.
+
+The reptiles, and some others of the lower animals, add still more to this
+weight of evidence. The true rattlesnakes are highly characteristic, and
+among the lizards are several genera of the peculiar American family, the
+Iguanidæ. Nowhere in the world are the tailed batrachians so largely
+developed as in this region, the Sirens and the Amphiumidæ forming two
+peculiar families, while there are nine peculiar genera of salamanders, and
+two others allied respectively to the Proteus of Europe and the Sieboldia
+or giant salamander of Japan. There are seven peculiar families and about
+thirty peculiar genera of fresh-water fishes; while the fresh-water
+molluscs are more numerous than in any other region, more than thirteen
+hundred species and varieties having been described.
+
+Combining the evidence derived from all these classes of animals, we find
+the Nearctic region to be exceedingly well characterised, and to be amply
+distinct from the Palæarctic. The few species that are common to the two
+are almost all arctic, or, at least, northern types, and may be compared
+with those desert forms which occupy the debatable ground between the
+Palæarctic, Ethiopian, and Oriental regions. {51} If, however, we compare
+the number of species, which are common to the Nearctic and Palæarctic
+regions with the number common to the western and eastern extremities of
+the latter region, we shall find a wonderful difference between the two
+cases; and if we further call to mind the number of important groups
+characteristic of the one region but absent from the other, we shall be
+obliged to admit that the relation that undoubtedly exists between the
+faunas of North America and Europe is of a very distinct nature from that
+which connects together Western Europe and North-eastern Asia in the bonds
+of zoological unity.
+
+_Definition and Characteristic Groups of the Neotropical Region._--The
+Neotropical region requires very little definition, since it comprises the
+whole of America south of the Nearctic region, with the addition of the
+Antilles or West Indian Islands. Its zoological peculiarities are almost as
+marked as those of Australia, which, however, it far exceeds in the extreme
+richness and variety of all its forms of life. To show how distinct it is
+from all the other regions of the globe, we need only enumerate some of the
+best known and more conspicuous of the animal forms which are peculiar to
+it. Such are, among mammalia--the prehensile-tailed monkeys and the
+marmosets, the blood-sucking bats, the coati-mundis, the peccaries, the
+llamas and alpacas, the chinchillas, the agoutis, the sloths, the
+armadillos, and the ant-eaters; a series of types more varied, and more
+distinct from those of the rest of the world than any other continent can
+boast of. Among birds we have the charming sugar-birds, forming the family
+Coerebidæ; the immense and wonderfully varied group of tanagers; the
+exquisite little manakins, and the gorgeously-coloured chatterers; the host
+of tree-creepers of the family Dendrocolaptidæ; the wonderful toucans; the
+puff-birds, jacamars, todies and motmots; the marvellous assemblage of four
+hundred distinct kinds of humming-birds; the gorgeous macaws; the
+curassows, the trumpeters, and the sun-bitterns. Here again there is no
+other continent or region that can produce such an assemblage of remarkable
+and perfectly distinct groups of birds; and no less wonderful is its
+richness in species, since these fully equal, if they do not surpass, those
+of the {52} two great tropical regions of the Eastern Hemisphere (the
+Ethiopian and the Oriental) combined.
+
+As an additional indication of the distinctness and isolation of the
+Neotropical region from all others, and especially from the whole Eastern
+Hemisphere, we must say something of the otherwise widely distributed
+groups which are absent. Among mammalia we have first the order
+Insectivora, entirely absent from South America, though a few species are
+found in Central America and the West Indies; the Viverridæ or civet family
+is wholly wanting, as are every form of sheep, oxen, or antelopes; while
+the swine, the elephants, and the rhinoceroses of the old world are
+represented by the diminutive peccaries and tapirs.
+
+Among birds we have to notice the absence of tits, true flycatchers,
+shrikes, sunbirds, starlings, larks (except a solitary species in the
+Andes), rollers, bee-eaters, and pheasants, while warblers are very scarce,
+and the almost cosmopolitan wagtails are represented by a single species of
+pipit.
+
+We must also notice the preponderance of low or archaic types among the
+animals of South America. Edentates, marsupials, and rodents form the
+majority of the terrestrial mammalia; while such higher groups as the
+carnivora and hoofed animals are exceedingly deficient. Among birds a low
+type of Passeres, characterised by the absence of the singing muscles, is
+excessively prevalent, the enormous groups of the ant-thrushes, tyrants,
+tree-creepers, manakins, and chatterers belonging to it. The Picariæ (a
+lower group) also prevail to a far greater extent than in any other
+regions, both in variety of forms and number of species; and the chief
+representatives of the gallinaceous birds--the curassows and tinamous, are
+believed to be allied, the former to the brush-turkeys of Australia, the
+latter (very remotely) to the ostriches, two of the least developed types
+of birds.
+
+Whether, therefore, we consider its richness in peculiar forms of animal
+life, its enormous variety of species, its numerous deficiencies as
+compared with other parts of the world, or the prevalence of a low type of
+organisation among its higher animals, the Neotropical region stands out as
+undoubtedly the most remarkable of the great zoological divisions of the
+earth.
+
+In reptiles, amphibia, fresh-water fishes, and insects, {53} this region is
+equally peculiar, but we need not refer to these here, our only object now
+being to establish by a sufficient number of well-known and easily
+remembered examples, the distinctness of each region from all others, and
+its unity as a whole. The former has now been sufficiently demonstrated,
+but it may be well to say a few words as to the latter point.
+
+The only outlying portions of the region about which there can be any doubt
+are--Central America, or that part of the region north of the Isthmus of
+Panama, the Antilles or West Indian Islands, and the temperate portion of
+South America including Chili and Patagonia.
+
+In Central America, and especially in Mexico, we have an intermixture of
+South American and North American animals, but the former undoubtedly
+predominate, and a large proportion of the peculiar Neotropical groups
+extend as far as Costa Rica. Even in Guatemala and Mexico we have howling
+and spider-monkeys, coati-mundis, tapirs, and armadillos; while chatterers,
+manakins, ant-thrushes, and other peculiarly Neotropical groups of birds
+are abundant. There is therefore no doubt as to Mexico forming part of this
+region, although it is comparatively poor, and exhibits the intermingling
+of temperate and tropical forms.
+
+The West Indies are less clearly Neotropical, their poverty in mammals as
+well as in most other groups being extreme, while great numbers of North
+American birds migrate there in winter. The resident birds, however,
+comprise trogons, sugar-birds, chatterers, with many humming-birds and
+parrots, representing eighteen peculiar Neotropical genera; a fact which
+decides the region to which the islands belong.
+
+South temperate America is also very poor as compared with the tropical
+parts of the region, and its insects contain a considerable proportion of
+north temperate forms. But it contains armadillos, cavies and opossums; and
+its birds all belong to American groups, though, owing to the inferior
+climate and deficiency of forests, a number of the families of birds
+peculiar to tropical America are wanting. Thus there are no manakins,
+chatterers, toucans, trogons, or motmots; but there are abundance of
+hang-nests, tyrant-birds, ant-thrushes, tree-creepers, and a fair {54}
+proportion of humming-birds, tanagers and parrots. The zoology is therefore
+thoroughly Neotropical, although somewhat poor; and it has a number of
+peculiar forms of strictly Neotropical types--as the chinchillas, alpacas,
+&c., which are not found in the tropical regions except in the high Andes.
+
+_Comparison of Zoological Regions with the Geographical Divisions of the
+Globe._--Having now completed our survey of the great zoological regions of
+the globe, we find that they do not differ so much from the old
+geographical divisions as our first example might have led us to suppose.
+Europe, Asia, Africa, Australia, North America, and South America, really
+correspond, each to a zoological region, but their boundaries require to be
+modified more or less considerably; and if we remember this, and keep their
+extensions or limitations always in our mind, we may use the terms "South
+American" or "North American," as being equivalent to Neotropical and
+Nearctic, without much inconvenience, while "African" and "Australian"
+equally well serve to express the zoological type of the Ethiopian and
+Australian regions. Europe and Asia require more important modifications.
+The European fauna does indeed well represent the Palæarctic in all its
+main features, and if instead of Asia we say tropical Asia we have the
+Oriental region very fairly defined; so that the relation of the
+geographical with the zoological primary divisions of the earth is
+sufficiently clear. In order to make these relations visible to the eye and
+more easily remembered, we will put them into a tabular form:
+
+ Regions. Geographical Equivalent.
+ Palæarctic EUROPE, with north temperate Africa and Asia.
+ Ethiopian AFRICA (south of the Sahara) with Madagascar.
+ Oriental TROPICAL ASIA, to Philippines and Java.
+ Australian AUSTRALIA, with Pacific Islands, Moluccas, &c.
+ Nearctic NORTH AMERICA, to North Mexico.
+ Neotropical SOUTH AMERICA, with tropical N. America and W. Indies.
+
+The following arrangement of the regions will indicate their geographical
+position, and to a considerable extent their relation to each other.
+
+ N E A R C T I C--P A L Æ A R C T I C
+ | | |
+ | | ORIENTAL
+ | ETHIOPIAN |
+ NEO- |
+ TROPICAL AUSTRALIAN
+
+ May 4th. Diameter of spot 31° 24'
+ June 4th. ,, ,, 28° 0'
+ ,, 17th. ,, ,, 22° 54'
+ July 4th. ,, ,, 18° 24'
+ ,, 12th. ,, ,, 15° 20'
+ ,, 20th. ,, ,, 18° 0'
+
+We thus see that Mars has two permanent snow-caps, of nearly equal size in
+winter but diminishing very unequally {55} in summer, when the southern cap
+is reduced to nearly one third the size of the northern; and this fact is
+held by Mr. Carpenter, as it was by the late Mr. Belt, to be opposed to the
+view of the hemisphere which has winter in _aphelion_ (as the southern now
+has both in the Earth and Mars), having been alone glaciated during periods
+of high excentricity.[9]
+
+Before, however, we can draw any conclusion from the case of Mars, we must
+carefully scrutinise the facts, and the conditions they imply. In the first
+place, there is evidently this radical difference between the state of Mars
+now and of the Earth during a glacial period--that Mars has no great
+ice-sheets spreading over its temperate zone, as the Earth undoubtedly had.
+This we know from the fact of the _rapid_ disappearance of the white
+patches over a belt three degrees wide in a fortnight (equal to a width of
+about 100 miles of our measure), and in the northern hemisphere of eight
+degrees wide (about 280 miles) between May 4th and July 12th. Even with our
+much more powerful sun, which gives us more than twice as much heat as Mars
+receives, no such diminution of an ice-sheet, or of glaciers of even
+moderate thickness, could possibly occur; but the phenomenon is on the
+contrary exactly analogous to what actually takes place on the plains of
+Siberia in summer. These, as I am informed by Mr. Seebohm, are covered with
+snow during winter and spring to a depth of six or eight feet, which
+diminishes very little even under the hot suns of May, till warm winds
+combine with the sun in June, when in about a fortnight the whole of it
+disappears, and a little later the whole of northern Asia is free from its
+winter covering. As, however, the sun of Mars is so much less powerful than
+ours, we may be {56} sure that the snow (if it is real snow) is much less
+thick--a mere surface-coating in fact, such as occurs in parts of Russia
+where the precipitation is less, and the snow accordingly does not exceed
+two or three feet in thickness.
+
+We now see the reason why the _southern_ pole of Mars parts with its white
+covering so much more quickly and to so much greater an extent than the
+_northern_, for the south pole during summer is nearest the sun, and, owing
+to the great excentricity of Mars, would have about one-third more heat
+than during the summer of the northern hemisphere; and this greater heat
+would cause the winds from the equator to be both warmer and more powerful,
+and able to produce the same effects on the scanty Martian snows as they
+produce on our northern snow-plains. The reason why both poles of Mars are
+almost equally snow-covered in winter is not difficult to understand. Owing
+to the greater obliquity of the ecliptic, and the much greater length of
+the year, the polar regions will be subject to winter darkness fully twice
+as long as with us, and the fact that one pole is nearer the sun during
+this period than the other at a corresponding period, will therefore make
+no perceptible difference. It is also probable that the two poles of Mars
+are approximately alike as regards their geographical features, and that
+neither of them is surrounded by very high land on which ice may
+accumulate. With us at the present time, on the other hand, geographical
+conditions completely mask and even reverse the influence of excentricity,
+and that of winter in _perihelion_ in the northern, and summer in
+_perihelion_ in the southern, hemisphere. In the north we have a
+preponderance of sea within the Arctic circle, and of lowlands in the
+temperate zone. In the south exactly opposite conditions prevail, for there
+we have a preponderance of land (and much of it high land) within the
+Antarctic circle, and of sea in the temperate zone. Ice, therefore,
+accumulates in the south, while a thin coating of snow, easily melted in
+summer, is the prevalent feature in the north; and these contrasts react
+upon climate to such an extent, that in the southern ocean, islands in the
+latitude of Ireland have glaciers descending to the level of the sea, and
+constant snowstorms {57} in the height of summer, although the sun is then
+actually nearer the earth than it is during our northern summer!
+
+It is evident, therefore, that the phenomena presented by the varying polar
+snows of Mars are in no way opposed to that modification of Dr. Croll's
+theory of the conditions which brought about the glacial epochs of our
+northern hemisphere, which is here advocated; but are perfectly explicable
+on the same general principles, if we keep in mind the distinction between
+an ice-sheet--which a summer's sun cannot materially diminish, but may even
+increase by bringing vapour to be condensed into snow--and a thin snowy
+covering which may be annually melted and annually renewed, with great
+rapidity and over large areas. Except within the small circles of perpetual
+polar snow there can at the present time be no ice-sheets in Mars; and the
+reason why this permanent snowy area is more extensive around the northern
+than around the southern pole may be partly due to higher land at the
+north, but is perhaps sufficiently explained by the diminished power of the
+summer sun, owing to its greatly increased distance at that season in the
+northern hemisphere, so that it is not able to melt so much of the snow
+which has accumulated during the long night of winter.
+
+ * * * * *
+
+
+{58}
+
+CHAPTER IX
+
+ANCIENT GLACIAL EPOCHS, AND MILD CLIMATES IN THE ARCTIC REGIONS
+
+ Dr. Croll's Views on Ancient Glacial Epochs--Effects of Denudation in
+ Destroying the Evidence of Remote Glacial Epochs--Rise of Sea-level
+ Connected with Glacial Epochs a Cause of Further Denudation--What
+ Evidence of Early Glacial Epochs may be Expected--Evidences of
+ Ice-action During the Tertiary Period--The Weight of the Negative
+ Evidence--Temperate Climates in the Arctic Regions--The Miocene Arctic
+ Flora--Mild Arctic Climates of the Cretaceous Period--Stratigraphical
+ Evidence of Long-continued Mild Arctic Conditions--The Causes of Mild
+ Arctic Climates--Geographical Conditions Favouring Mild Northern
+ Climates in Tertiary Times--The Indian Ocean as a Source of Heat in
+ Tertiary Times--Condition of North America During the Tertiary
+ Period--Effect of High Excentricity on Warm Polar Climates--Evidences
+ as to Climate in the Secondary and Palæozoic Epochs--Warm Arctic
+ Climates in Early Secondary and Palæozoic Times--Conclusions as to the
+ Climates of Secondary and Tertiary Periods--General View of Geological
+ Climates as Dependent on the Physical Features of the Earth's
+ Surface--Estimate of the Comparative Effects of Geographical and
+ Physical Causes in Producing Changes of Climate.
+
+If we adopt the view set forth in the preceding chapter as to the character
+of the glacial epoch and of the accompanying alternations of climate, it
+must have been a very important agent in producing changes in the
+distribution of animal and vegetable life. The intervening mild periods,
+which almost certainly occurred during its earlier and later phases, may
+have been sometimes more equable than even our present insular climate, and
+severe frosts were probably then unknown. During the four or five {59}
+thousand years that each specially mild period may have lasted, some
+portions of the north temperate zone, which had been buried in snow or ice,
+would become again clothed with vegetation and stocked with animal life,
+both of which, as the cold again came on, would be driven southward, or
+perhaps partially exterminated. Forms usually separated would thus be
+crowded together, and a struggle for existence would follow, which must
+have led to the modification or the extinction of many species. When the
+survivors in the struggle had reached a state of equilibrium, a fresh field
+would be opened to them by the later ameliorations of climate; the more
+successful of the survivors would spread and multiply; and after this had
+gone on for thousands of generations, another change of climate, another
+southward migration, another struggle of northern and southern forms would
+take place.
+
+But if the last glacial epoch has coincided with, and has been to a
+considerable extent caused by, a high excentricity of the earth's orbit, we
+are naturally led to expect that earlier glacial epochs would have occurred
+whenever the excentricity was unusually large. Dr. Croll has published
+tables showing the varying amounts of excentricity for three million years
+back; and from these it appears that there have been many periods of high
+excentricity, which has often been far greater than at the time of the last
+glacial epoch.[10] The accompanying diagram has been drawn from these
+tables, and it will be seen that the highest excentricity occurred 850,000
+years ago, at which time the difference between the sun's distance at
+_aphelion_ and _perihelion_ was thirteen and a half millions of miles,
+whereas during the last glacial period the maximum difference was ten and a
+half million miles.
+
+[Illustration: DIAGRAM SHOWING THE CHANGES OF EXCENTRICITY DURING THE LAST
+THREE MILLION YEARS.]
+
+Now, judging by the amount of organic and physical change that occurred
+during and since the glacial epoch, and that which has occurred since the
+Miocene period, it is considered probable that this maximum of excentricity
+coincided with some part of the latter period; and Dr. Croll maintains that
+a glacial epoch must then have {60} occurred surpassing in severity that of
+which we have such convincing proofs, and consisting like it of
+alternations of cold and warm phases every 10,500 years. The diagram also
+shows us another long-continued period of high excentricity from 1,750,000
+to 1,950,000 years ago, and yet another almost equal to the maximum
+2,500,000 years back. These may perhaps have occurred during the Eocene and
+Cretaceous epochs respectively, or all may have been included within the
+limits of the Tertiary period. As two of these high excentricities greatly
+exceed that which caused our glacial epoch, while the third is almost equal
+to it and of longer duration, they seem to afford us the means of testing
+rival theories of the causes of glaciation. If, as Dr. Croll argues, high
+excentricity is the great and dominating agency in bringing on glacial
+epochs, geographical changes being subordinate, then there must have been
+glacial epochs of great severity at all these three periods; while if he is
+also correct in supposing that the alternate phases of precession would
+inevitably produce glaciation in one hemisphere, and a proportionately mild
+and equable climate in the opposite hemisphere, then we should have to look
+for evidence of exceptionally warm and exceptionally cold periods,
+occurring {61} alternately and with several repetitions, within a space of
+time which, geologically speaking, is very short indeed.
+
+Let us then inquire first into the character of the evidence we should
+expect to find of such changes of climate, if they have occurred; we shall
+then be in a better position to estimate at its proper value the evidence
+that actually exists, and, after giving it due weight, to arrive at some
+conclusion as to the theory that best explains and harmonises it.
+
+
+
+_Effects of Denudation in Destroying the Evidence of Remote Glacial
+Epochs._--It may be supposed, that if earlier glacial epochs than the last
+did really occur, we ought to meet with some evidence of the fact
+corresponding to that which has satisfied us of the extensive recent
+glaciation of the northern hemisphere; but Dr. Croll and other writers have
+ably argued that no such evidence is likely to be found. It is now
+generally admitted that sub-aërial denudation is a much more powerful agent
+in lowering and modifying the surface of a country than was formerly
+supposed. It has in fact been proved to be so powerful that the difficulty
+now felt is, not to account for the denudation which can be proved to have
+occurred, but to explain the apparent persistence of superficial features
+which ought long ago to have been destroyed.
+
+A proof of the lowering and eating away of the land-surface which every one
+can understand, is to be found in the quantity of solid matter carried down
+to the sea and to low grounds by rivers. This is capable of pretty accurate
+measurement, and it has been carefully measured for several rivers, large
+and small, in different parts of the world. The details of these
+measurements will be given in a future chapter, and it is only necessary
+here to state that the average of them all gives us this result--that one
+foot must, on an average, be taken off the entire surface of the land each
+3,000 years in order to produce the amount of sediment and matter in
+solution which is actually carried into the sea. To give an idea of the
+limits of variation in different rivers it may be mentioned that the
+Mississippi is one which denudes its valley at a slow rate, taking 6,000
+{62} years to remove one foot; while the Po is the most rapid, taking only
+729 years to do the same work in its valley. The cause of this difference
+is very easy to understand. A large part of the area of the Mississippi
+basin consists of the almost rainless prairie and desert regions of the
+west, while its sources are in comparatively arid mountains with scanty
+snow-fields, or in a low forest-clad plateau. The Po, on the other hand, is
+wholly in a district of abundant rainfall, while its sources are spread
+over a great amphitheatre of snowy Alps nearly 400 miles in extent, where
+the denuding forces are at a maximum. As Scotland is a mountain region of
+rather abundant rainfall, the denuding power of its rains and rivers is
+probably rather above than under the average, but to avoid any possible
+exaggeration we will take it at a foot in 4,000 years.
+
+Now if the end of the glacial epoch be taken to coincide with the
+termination of the last period of high excentricity, which occurred about
+80,000 years ago (and no geologist will consider this too long for the
+changes which have since taken place), it follows that the entire surface
+of Scotland must have been since lowered an average amount of twenty feet.
+But over large areas of alluvial plains, and wherever the rivers have
+spread during floods, the ground will have been raised instead of lowered;
+and on all nearly level ground and gentle slopes there will have been
+comparatively little denudation; so that proportionally much more must have
+been taken away from mountain sides and from the bottoms of valleys having
+a considerable downward slope. One of the very highest authorities on the
+subject of denudation, Mr. Archibald Geikie, estimates the area of these
+more rapidly denuded portions as only one-tenth of the comparatively level
+grounds, and he further estimates that the former will be denuded about ten
+times as fast as the latter. It follows that the valleys will be deepened
+and widened on the average about five feet in the 4,000 years instead of
+one foot; and thus many valleys must have been deepened and widened 100
+feet, and some even more, since the glacial epoch, while the more level
+portions of the country will have been lowered on the average only about
+two feet. {63}
+
+Now Dr. Croll gives us the following account of the present aspect of the
+surface of a large part of the country:--
+
+"Go where one will in the lowlands of Scotland and he shall hardly find a
+single acre whose upper surface bears the marks of being formed by the
+denuding agents now in operation. He will observe everywhere mounds and
+hollows which cannot be accounted for by the present agencies at work....
+In regard to the general surface of the country the present agencies may be
+said to be just beginning to carve a new line of features out of the old
+glacially-formed surface. But so little progress has yet been made, that
+the kames, gravel-mounds, knolls of boulder clay, &c., still retain in most
+cases their original form."[11]
+
+The facts here seem a little inconsistent, and we must suppose that Dr.
+Croll has somewhat exaggerated the universality and complete preservation
+of the glaciated surface. The amount of average denudation, however, is not
+a matter of opinion but of measurement; and its consequences can in no way
+be evaded. They are, moreover, strictly proportionate to the time elapsed;
+and if so much of the old surface of the country has certainly been
+remodelled or carried into the sea since the last glacial epoch, it becomes
+evident that any surface-phenomena produced by still earlier glacial epochs
+_must_ have long since entirely disappeared.
+
+_Rise of the Sea-level Connected with Glacial Epochs, a Cause of Further
+Denudation._--There is also another powerful agent that must have assisted
+in the destruction of any such surface deposits or markings. During the
+last glacial epoch itself there were several minor oscillations of the
+land, without counting the great submergence of over 1,300 feet, supposed
+to be indicated by patches of shelly clays and gravels in Wales and
+Ireland, and also in a few localities in England and Scotland, since these
+are otherwise explained by many geologists. Other subsidences have no doubt
+occurred in the same areas during the Tertiary epoch, and some writers
+connect these subsidences with the glacial {64} period itself, the unequal
+amount of ice at the two poles causing the centre of gravity of the earth
+to be displaced when, of course, the surface of the ocean will conform to
+it and appear to rise in the one hemisphere and sink in the other. If this
+is the case, subsidences of the land are natural concomitants of a glacial
+period, and will powerfully aid in removing all evidence of its occurrence.
+We have seen reason to believe, however, that during the height of the
+glacial epoch the extreme cold persisted through the successive phases of
+precession, and if so, both polar areas would probably be glaciated at
+once. This would cause the abstraction of a large quantity of water from
+the ocean, and a proportionate elevation of the land, which would react on
+the accumulation of snow and ice, and thus add another to that wonderful
+series of physical agents which act and react on each other so as to
+intensify glacial epochs.
+
+But whether or not these causes would produce any important fluctuations of
+the sea-level is of comparatively little importance to our present inquiry,
+because the wide extent of marine Tertiary deposits in the northern
+hemisphere and their occurrence at considerable elevations above the
+present sea-level, afford the most conclusive proofs that great changes of
+sea and land have occurred throughout the entire Tertiary period; and these
+repeated submergences and emergences of the land combined with sub-aërial
+and marine denudation, would undoubtedly destroy all those superficial
+evidences of ice-action on which we mainly depend for proofs of the
+occurrence of the last glacial epoch.
+
+_What Evidence of Early Glacial Epochs may be Expected._--Although we may
+admit the force of the preceding argument as to the extreme improbability
+of our finding any clear evidence of the superficial action of ice during
+remote glacial epochs, there is nevertheless one kind of evidence that we
+ought to find, because it is both wide-spread and practically
+indestructible.
+
+One of the most constant of all the phenomena of a glaciated country is the
+abundance of icebergs produced by the breaking off of the ends of glaciers
+which terminate {65} in arms of the sea, or of the terminal face of the
+ice-sheet which passes beyond the land into the ocean. In both these cases
+abundance of rocks and _débris_, such as form the terminal moraines of
+glaciers on land, are carried out to sea and deposited over the sea-bottom
+of the area occupied by icebergs. In the case of an ice-sheet it is almost
+certain that much of the ground-moraine, consisting of mud and imbedded
+stones, similar to that which forms the "till" when deposited on land, will
+be carried out to sea with the ice and form a deposit of marine "till" near
+the shore.
+
+It has indeed been objected that when an ice-sheet covered an entire
+country there would be no moraines, and that rocks or _débris_ are very
+rarely seen on icebergs. But during every glacial epoch there will be a
+southern limit to the glaciated area, and everywhere near this limit the
+mountain-tops will rise far above the ice and deposit on it great masses of
+_débris_; and as the ice-sheet spreads, and again as it passes away, this
+moraine-forming area will successively occupy the whole country. But even
+such an ice-clad country as Greenland is now known to have protruding peaks
+and rocky masses which give rise to moraines on its surface;[12] and, as
+rocks from Cumberland and Ireland were carried by the ice-sheet to the Isle
+of Man, there must have been a very long period during which the ice-sheets
+of Britain and Ireland terminated in the ocean and sent off abundance of
+rock-laden bergs into the surrounding seas; and the same thing must have
+occurred along all the coasts of Northern Europe and Eastern America.
+
+We cannot therefore doubt that throughout the greater part of the duration
+of a glacial epoch the seas adjacent to the glaciated countries would
+receive continual deposits of large rocks, rock-fragments, and gravel,
+similar to the material of modern and ancient moraines, and analogous to
+the drift and the numerous travelled blocks which the ice has undoubtedly
+scattered broadcast over every glaciated country; and these rocks and
+boulders would be imbedded in whatever deposits were then forming, either
+from the matter carried down by rivers or from the mud ground off {66} the
+rocks and carried out to sea by the glaciers themselves. Moreover, as
+icebergs float far beyond the limits of the countries which gave them
+birth, these ice-borne materials would be largely imbedded in deposits
+forming from the denudation of countries which had never been glaciated, or
+from which the ice had already disappeared.
+
+But if every period of high excentricity produced a glacial epoch of
+greater or less extent and severity, then, on account of the frequent
+occurrence of a high phase of excentricity during the three million years
+for which we have the tables, these boulder and rock-strewn deposits would
+be both numerous and extensive. Four hundred thousand years ago the
+excentricity was almost exactly the same as it is now, and it continually
+increased from that time up to the glacial epoch. Now if we take double the
+present excentricity as being sufficient to produce some glaciation in the
+temperate zone, we find (by drawing out the diagram at p. 171 on a larger
+scale) that during 1,150,000 years out of the 2,400,000 years immediately
+preceding the last glacial epoch, the excentricity reached or exceeded this
+amount, consisting of sixteen separate epochs, divided from each other by
+periods varying from 30,000 to 200,000 years. But if the last glacial epoch
+was at its maximum 200,000 years ago, a space of three million years will
+certainly include much, if not all, of the Tertiary period; and even if it
+does not, we have no reason to suppose that the character of the
+excentricity would suddenly change beyond the three million years.
+
+It follows, therefore, that if periods of high excentricity, like that
+which appears to have been synchronous with our last glacial epoch and is
+generally admitted to have been one of its efficient causes, always
+produced glacial epochs (with or without alternating warm periods), then
+the whole of the Tertiary deposits in the north temperate and Arctic zones
+should exhibit frequent alternations of boulder and rock-bearing beds, or
+coarse rock-strewn gravels analogous to our existing glacial drift, and
+with some corresponding change of organic remains. Let us then see what
+evidence can be adduced of the existence of such deposits, and whether it
+is adequate to support the {67} theory of repeated glacial epochs during
+the Tertiary period.
+
+_Evidences of Ice-action during the Tertiary Period._--The Tertiary fossils
+both of Europe and North America indicate throughout warm or temperate
+climates, except those of the more recent Pliocene deposits which merge
+into the earlier glacial beds. The Miocene deposits of Central and Southern
+Europe, for example, contain marine shells of some genera now only found
+farther south, while the fossil plants often resemble those of Madeira and
+the southern states of North America. Large reptiles, too, abounded, and
+man-like apes lived in the south of France and in Germany. Yet in Northern
+Italy, near Turin, there are beds of sandstone and conglomerate full of
+characteristic Miocene shells, but containing in an intercalated deposit
+angular blocks of serpentine and greenstone often of enormous size, one
+being fourteen feet long, and another twenty-six feet. Some of the blocks
+were observed by Sir Charles Lyell to be faintly striated and partly
+polished on one side, and they are scattered through the beds for a
+thickness of nearly 150 feet. It is interesting that the particular bed in
+which the blocks occur yields no organic remains, though these are
+plentiful both in the underlying and overlying beds, as if the cold of the
+icebergs, combined with the turbidity produced by the glacial mud, had
+driven away the organisms adapted to live only in a comparatively warm sea.
+Rock similar in kind to these erratics occurs about twenty miles distant in
+the Alps.
+
+The Eocene period is even more characteristically tropical in its flora and
+fauna, since palms and Cycadaceæ, turtles, snakes, and crocodiles then
+inhabited England. Yet on the north side of the Alps, extending from
+Switzerland to Vienna, and also south of the Alps near Genoa, there is a
+deposit of finely-stratified sandstone several thousand feet in thickness,
+quite destitute of organic remains, but containing in several places in
+Switzerland enormous blocks either angular or partly rounded, and composed
+of oolitic limestone or of granite. Near the Lake of Thun some of the
+granite blocks found in this deposit are of enormous size, one of them
+being 105 feet long, ninety feet wide, {68} and forty-five feet thick! The
+granite is red, and of a peculiar kind which cannot be matched anywhere in
+the Alps, or indeed elsewhere. Similar erratics have also been found in
+beds of the same age in the Carpathians and in the Apennines, indicating
+probably an extensive inland European sea into which glaciers descended
+from the surrounding mountains, depositing these erratics, and cooling the
+water so as to destroy the mollusca and other organisms which had
+previously inhabited it. It is to be observed that wherever these erratics
+occur they are always in the vicinity of great mountain ranges; and
+although these can be proved to have been in great part elevated during the
+Tertiary period, we must also remember that they must have been since very
+much lowered by denudation, of the amount of which, the enormously thick
+Eocene and Miocene beds now forming portions of them is in some degree a
+measure as well as a proof. It is not therefore at all improbable that
+during some part of the Tertiary period these mountains may have been far
+higher than they are now, and this we know might be sufficient for the
+production of glaciers descending to the sea-level, even were the climate
+of the lowlands somewhat warmer than at present.[13]
+
+_The Weight of the Negative Evidence._--But when we proceed to examine the
+Tertiary deposits of other parts of {69} Europe, and especially of our own
+country, for evidence of this kind, not only is such evidence completely
+wanting, but the facts are of so definite a character as to satisfy most
+geologists that it can never have existed; and the same maybe said of
+temperate North America and of the Arctic regions generally.
+
+In his carefully written paper on "The Climate Controversy" the late Mr.
+Searles V. Wood, Jun., remarks on this point as follows: "Now the Eocene
+formation is complete in England, and is exposed in continuous section
+along the north coast of the Isle of Wight from its base to its junction
+with the Oligocene (or Lower Miocene according to some), and along the
+northern coast of Kent from its base to the Lower Bagshot Sand. It has been
+intersected by railway and other cuttings in all directions and at all
+horizons, and pierced by wells innumerable; while from its strata in
+England, France, and Belgium, the most extensive collections of organic
+remains have been made of any formation yet explored, and from nearly all
+its horizons, for at one place or another in these three countries nearly
+every horizon may be said to have yielded fossils of some kind. These
+fossils, however, whether they be the remains of a flora such as that of
+Sheppey, or of a vertebrate fauna containing the crocodile and alligator,
+such as is yielded by beds indicative of terrestrial conditions, or of a
+molluscan assemblage such as is present in marine or fluvio-marine beds of
+the formation, are of unmistakably tropical or sub-tropical character
+throughout; and no trace whatever has appeared of the intercalation of a
+glacial period, much less of successive intercalations indicative of more
+than one period of 10,500 years' glaciation. Nor can it be urged that the
+glacial epochs of the Eocene in England were intervals of dry land, and so
+have left no evidence of their existence behind them, because a large part
+of the continuous sequence of Eocene deposits in this country consists of
+alternations of fluviatile, fluvio-marine, and purely marine strata; so
+that it seems impossible that during the accumulation of the Eocene
+formation in England a glacial period could have occurred without its
+evidences being {70} abundantly apparent. The Oligocene of Northern Germany
+and Belgium, and the Miocene of those countries and of France, have also
+afforded a rich molluscan fauna, which, like that of the Eocene, has as yet
+presented no indication of the intrusion of anything to interfere with its
+uniformly sub-tropical character."[14]
+
+This is sufficiently striking; but when we consider that this enormous
+series of deposits, many thousand feet in thickness, consists wholly of
+alternations of clays, sands, marls, shales, or limestones, with a few beds
+of pebbles or conglomerate, not one of the whole series containing
+irregular blocks of foreign material, boulders or gravel, such as we have
+seen to be the essential characteristic of a glacial epoch; and when we
+find that this same general character pervades all the extensive Tertiary
+deposits of temperate North America, we shall, I think, be forced to the
+conclusion that no general glacial epochs could have occurred during their
+formation. It must be remembered that the "imperfection of the geological
+record" will not help us here, because the series of Tertiary deposits is
+unusually complete, and we must suppose some destructive agency to have
+selected all the intercalated glacial beds and to have so completely made
+away with them that not a fragment remains, while preserving all or almost
+all the _interglacial_ beds; and to have acted thus capriciously, not in
+one limited area only, but over the whole northern hemisphere, with the
+local exceptions on the flanks of great mountain ranges already referred
+to.
+
+_Temperate Climates in the Arctic Regions._--As we have just seen, the
+geological evidence of the persistence of sub-tropical or warm climates in
+the north temperate zone during the greater part of the Tertiary period is
+almost irresistible, and we have now to consider the still more
+extraordinary series of observations which demonstrate that this
+amelioration of climate extended into the Arctic zone, and into countries
+now almost wholly buried in snow and ice. These warm Arctic climates have
+been explained by Dr. Croll as due to periods of high excentricity with
+winter in _perihelion_, a theory which implies alternating {71} epochs of
+glaciation far exceeding what now prevails; and it is therefore necessary
+to examine the evidence pretty closely in order to see if this view is more
+tenable in the case of the north polar regions than we have found it to be
+in that of the north temperate zone.
+
+The most recent of these milder climates is perhaps indicated by the
+abundant remains of large mammalia--such as the mammoth, woolly rhinoceros,
+bison and horse, in the icy alluvial plains of Northern Siberia, and
+especially in the Liakhov Islands in the same latitude as the North Cape of
+Asia. These remains occur not in one or two spots only, as if collected by
+eddies at the mouth of a river, but along the whole borders of the Arctic
+Ocean; and it is generally admitted that the animals must have lived upon
+the adjacent plains, and that a considerably milder climate than now
+prevails could alone have enabled them to do so. How long ago this occurred
+we do not know, but one of the last intercalated mild periods of the
+glacial epoch itself seems to offer all the necessary conditions. Again,
+Sir Edward Belcher discovered on the dreary shores of Wellington Channel in
+75ϡ N. Lat. the trunk and root of a fir tree which had evidently grown
+where it was found. It appeared to belong to the species _Abies alba_, or
+white fir, which now reaches 68° N. Lat. and is the most northerly conifer
+known. Similar trees, one four feet in circumference and thirty feet long,
+were found by Lieut. Mecham in Prince Patrick's Island in Lat. 76° 12' N.,
+and other Arctic explorers have found remains of trees in high
+latitudes.[15]
+
+Similar indications of a recent milder climate are found in Spitzbergen.
+Professor Nordenskjöld says: "At various places on Spitzbergen, at the
+bottom of Lomme Bay, at Cape Thordsen, in Blomstrand's strata in Advent
+Bay, there are found large and well-developed shells of a bivalve, _Mytilus
+edulis_, which is not now found living on the coast of Spitzbergen, though
+on the west coast of Scandinavia it everywhere covers the rocks near the
+sea-shore. These shells occur most plentifully in the bed of a river which
+runs through Reindeer Valley at Cape Thordsen. They {72} are probably
+washed out of a thin bed of sand at a height of about twenty or thirty feet
+above the present sea-level, which is intersected by the river. The
+geological age of this bed cannot be very great, and it has clearly been
+formed since the present basin of the Ice Sound, or at least the greater
+part of it, has been hollowed out by glacial action."[16]
+
+_The Miocene Arctic Flora._--One of the most startling and important of the
+scientific discoveries of the last forty years has been that of the relics
+of a luxuriant Miocene flora in various parts of the Arctic regions. It is
+a discovery that was totally unexpected, and is even now considered by many
+men of science to be completely unintelligible; but it is so thoroughly
+established, and it has such a direct and important bearing on the subjects
+we are discussing in the present volume, that it is necessary to lay a
+tolerably complete outline of the facts before our readers.
+
+The Miocene flora of temperate Europe was very like that of Eastern Asia,
+Japan, and the warmer part of Eastern North America of the present day. It
+is very richly represented in Switzerland by well preserved fossil remains,
+and after a close comparison with the flora of other countries Professor
+Heer concludes that the Swiss Lower Miocene flora indicates a climate
+corresponding to that of Louisiana, North Africa, and South China, while
+the Upper Miocene climate of the same country would correspond to that of
+the south of Spain, Southern Japan, and Georgia (U.S. of America). Of this
+latter flora, found chiefly at Oeninghen in the northern extremity of
+Switzerland, 465 species are known, of which 166 species are trees or
+shrubs, half of them being evergreens. They comprise sequoias like the
+Californian giant trees, camphor-trees, cinnamons, sassafras, bignonias,
+cassias, gleditschias, tulip-trees, and many other American genera,
+together with maples, ashes, planes, oaks, poplars, and other familiar
+European trees represented by a variety of extinct species. If we now go to
+the west coast of Greenland in 70° N. Lat. we find abundant remains of a
+flora of the same general {73} type as that of Oeninghen but of a more
+northern character. We have a sequoia identical with one of the species
+found at Oeninghen, a chestnut, salisburia, liquidambar, sassafras, and
+even a magnolia. We have also seven species of oaks, two planes, two vines,
+three beeches, four poplars, two willows, a walnut, a plum, and several
+shrubs supposed to be evergreens; altogether 137 species, mostly well and
+abundantly preserved!
+
+But even further north, in Spitzbergen, in 78° and 79° N. Lat. and one of
+the most barren and inhospitable regions on the globe, an almost equally
+rich fossil flora has been discovered including several of the Greenland
+species, and others peculiar, but mostly of the same genera. There seem to
+be no evergreens here except coniferæ, one of which is identical with the
+swamp-cypress (_Taxodium distichum_) now found living in the Southern
+United States! There are also eleven pines, two Libocedrus, two sequoias,
+with oaks, poplars, birches, planes, limes, a hazel, an ash, and a walnut;
+also water-lilies, pond-weeds, and an iris--altogether about a hundred
+species of flowering plants. Even in Grinnell Land, within 8Πdegrees of
+the pole, a similar flora existed, twenty-five species of fossil plants
+having been collected by the last Arctic expedition, of which eighteen were
+identical with the species from other Arctic localities. This flora
+comprised poplars, birches, hazels, elms, viburnums, and eight species of
+conifers including the swamp cypress and the Norway spruce (_Pinus abies_)
+which last does not now extend beyond 69ϡ N.
+
+Fossil plants closely resembling those just mentioned have been found at
+many other Arctic localities, especially in Iceland, on the Mackenzie River
+in 65° N. Lat. and in Alaska. As an intermediate station we have, in the
+neighbourhood of Dantzic in Lat. 55° N., a similar flora, with the
+swamp-cypress, sequoias, oaks, poplars, and some cinnamons, laurels, and
+figs. A little further south, near Breslau, north of the Carpathians, a
+rich flora has been found allied to that of Oeninghen, but wanting in some
+of the more tropical forms. Again, in the Isle of Mull in Scotland, in
+about 56ϡ N. Lat., a plant-bed has been discovered {74} containing a
+hazel, a plane, and a sequoia, apparently identical with a Swiss Miocene
+species.
+
+We thus find one well-marked type of vegetation spread from Switzerland and
+Vienna to North Germany, Scotland, Iceland, Greenland, Alaska, and
+Spitzbergen, some few of the species even ranging over the extremes of
+latitude between Oeninghen and Spitzbergen, but the great majority being
+distinct, and exhibiting decided indications of a decrease of temperature
+according to latitude, though much less in amount than now exists. Some
+writers have thought that the great similarity of the floras of Greenland
+and Oeninghen is a proof that they were not contemporaneous, but
+successive; and that of Greenland has been supposed to be as old as the
+Eocene. But the arguments yet adduced do not seem to prove such a
+difference of age, because there is only that amount of specific and
+generic diversity between the two which might be produced by distance and
+difference of temperature, under the exceptionally equable climate of the
+period. We have even now examples of an equally wide range of well-marked
+types; as in temperate South America, where many of the genera and some of
+the species range from the Straits of Magellan to Valparaiso--places
+differing as much in latitude as Switzerland and West Greenland; and the
+same may be said of North Australia and Tasmania, where, at a greater
+latitudinal distance apart, closely allied forms of Eucalyptus, Acacia,
+Casuarina, Stylidium, Goodenia, and many other genera would certainly form
+a prominent feature in any fossil flora now being preserved.
+
+_Mild Arctic Climates of the Cretaceous Period._--In the Upper Cretaceous
+deposits of Greenland (in a locality not far from those of the Miocene age
+last described) another remarkable flora has been discovered, agreeing
+generally with that of Europe and North America of the same geological age.
+Sixty-five species of plants have been identified, of which there are
+fifteen ferns, two cycads, eleven coniferæ, three monocotyledons, and
+thirty-four dicotyledons. One of the ferns is a tree-fern with thick stems,
+which has also been found in the Upper Greensand of England. Among the
+conifers the giant sequoias are found, and among {75} the dicotyledons the
+genera Populus, Myrica, Ficus, Sassafras, Andromeda, Diospyros, Myrsine,
+Panax, as well as magnolias, myrtles, and leguminosæ. Several of these
+groups occur also in the much richer deposits of the same age in North
+America and Central Europe; but all of them evidently afford such
+fragmentary records of the actual flora of the period, that it is
+impossible to say that any genus found in one locality was absent from the
+other merely because it has not yet been found there. On the whole, there
+seems to be less difference between the floras of Arctic and temperate
+latitudes in Upper Cretaceous than in Miocene times.
+
+In the same locality in Greenland (70° 33' N. Lat. and 52° W. Long.), and
+also in Spitzbergen, a more ancient flora, of Lower Cretaceous age, has
+been found; but it differs widely from the other in the great abundance of
+cycads and conifers and the scarcity of exogens, which latter are
+represented by a single poplar. Of the thirty-eight ferns, fifteen belong
+to the genus Gleichenia now almost entirely tropical. There are four genera
+of cycads, and three extinct genera of conifers, besides Glyptostrobus and
+Torreya now found only in China and California, six species of true pines,
+and five of the genus Sequoia, one of which occurs also in Spitzbergen. The
+European deposits of the same age closely agree with these in their general
+character, conifers, cycads, and ferns forming the mass of the vegetation,
+while exogens are entirely absent, the above-named Greenland poplar being
+the oldest known dicotyledonous plant.[17]
+
+If we take these facts as really representing the flora of the period, we
+shall be forced to conclude that, measured by the change effected in its
+plants, the lapse of time between the Lower and Upper Cretaceous deposits
+was far greater than between the Upper Cretaceous and the Miocene--a
+conclusion quite opposed to the indications afforded by the mollusca and
+the higher animals of the two periods. It seems probable, therefore, that
+these Lower Cretaceous plants represent local peculiarities of {76}
+vegetation such as now sometimes occur in tropical countries. On sandy or
+coralline islands in the Malay Archipelago there will often be found a
+vegetation consisting almost wholly of cycads, pandani, and palms, while a
+few miles off, on moderately elevated land, not a single specimen of either
+of these families may be seen, but a dense forest of dicotyledonous trees
+covering the whole country. A lowland vegetation, such as that above
+described, might be destroyed and its remains preserved by a slight
+depression, allowing it to be covered up by the detritus of some adjacent
+river, while not only would the subsidence of high land be a less frequent
+occurrence, but when it did occur the steep banks would be undermined by
+the waves, and the trees falling down would be floated away, and would
+either be cast on some distant shore or slowly decay on the surface or in
+the depths of the ocean.
+
+From the remarkable series of facts now briefly summarized, we learn, that
+whenever plant-remains have been discovered within the Arctic regions,
+either in Tertiary or Cretaceous deposits, they show that the climate was
+one capable of supporting a rich vegetation of trees, shrubs, and
+herbaceous plants, similar in general character to that which prevailed in
+the temperate zone at the same periods, but showing the influence of a less
+congenial climate. These deposits belong to at least four distinct
+geological horizons, and have been found widely scattered within the Arctic
+circle, yet nowhere has any proof been obtained of intercalated cold
+periods, such as would be indicated by the remains of a stunted vegetation,
+or a molluscan fauna similar to that which now prevails there.
+
+_Stratigraphical Evidence of Long-Continued Mild Arctic Conditions._--Let
+us now turn to the stratigraphical evidence, which, as we have already
+shown, offers a crucial test of the occurrence or non-occurrence of
+glaciation during any extensive geological period; and here we have the
+testimony of perhaps the greatest living authority on Arctic
+geology--Professor Nordenskjöld. In his lecture on "The Former Climate of
+the Polar Regions," he says: "The character of the coasts in the Arctic
+regions is especially favourable to geological investigations. While the
+valleys are for the {77} most part filled with ice, the sides of the
+mountains in summer, even in the 80th degree of latitude, and to a height
+of 1,000 or 1,500 feet above the level of the sea, are almost wholly free
+from snow. Nor are the rocks covered with any amount of vegetation worth
+mentioning; and, moreover, the sides of the mountains on the shore itself
+frequently present perpendicular sections, which everywhere expose their
+bare surfaces to the investigator. The knowledge of a mountain's geognostic
+character, at which one, in the more southerly countries, can only arrive
+after long and laborious researches, removal of soil and the like, is here
+gained almost at the first glance; and as we have never seen in Spitzbergen
+nor in Greenland, in these sections often many miles in length, and
+including one may say all formations from the Silurian to the Tertiary, any
+boulders even as large as a child's head, there is not the smallest
+probability that strata of any considerable extent, containing boulders,
+are to be found in the polar tracts previous to the middle of the Tertiary
+period. Since, then, both an examination of the geognostic condition, and
+an investigation of the fossil flora and fauna of the polar lands, show no
+signs of a glacial era having existed in those parts before the termination
+of the Miocene period, we are fully justified in rejecting, on the evidence
+of actual observation, the hypotheses founded on purely theoretical
+speculations, which assume the many times repeated alternation of warm and
+glacial climates between the present time and the earliest geological
+ages."[18] And again, in his _Sketch of the Geology of Spitzbergen_, after
+describing the various formations down to the Miocene, he says: "All the
+fossils found in the foregoing strata show that Spitzbergen, during former
+geological ages, enjoyed a magnificent climate, which indeed was somewhat
+colder during the Miocene period, but was still favourable for an
+extraordinarily abundant vegetation, much more luxuriant than that which
+now occurs even in the southern part of Scandinavia: and I have in those
+strata sought in vain for any sign, that, as some geologists have of late
+endeavoured to render probable, these favourable climatic conditions have
+been broken off {78} by intervals of ancient glacial periods. The profiles
+I have had the opportunity to examine during my various Spitzbergen
+expeditions would certainly, if laid down on a line, occupy an extent of _a
+thousand English miles_; and if any former glacial period had existed in
+this region, there ought to have been some trace to be observed of erratic
+blocks, or other formations which distinguish glacial action. But this has
+not been the case. In the strata, whose length I have reckoned alone, I
+have not found a single fragment of a foreign rock so large as a child's
+head."[19]
+
+Now it is quite impossible to ignore or evade the force of this testimony
+as to the continuous warm climates of the north temperate and polar zones
+throughout Tertiary times. The evidence extends over a vast area, both in
+space and time, it is derived from the work of the most competent living
+geologists, and it is absolutely consistent in its general tendency. We
+have in the Lower Cretaceous period an almost tropical climate in France
+and England, a somewhat lower temperature in the United States, and a mild
+insular climate in the Arctic regions. In each successive period the
+climate becomes somewhat less tropical; but down to the Upper Miocene it
+remains warm temperate in Central Europe, and cold temperate within the
+polar area, with not a trace of any intervening periods of Arctic cold. It
+then gradually cools down and merges through the Pliocene into the glacial
+epoch in Europe, while in the Arctic zone there is a break in the record
+between the Miocene and the recent glacial deposits.[20]
+
+{79}
+
+Accepting this as a substantially correct account of the general climatic
+aspect of the Tertiary period in the northern hemisphere, let us see
+whether the principles we have already laid down will enable us to give a
+satisfactory explanation of its causes.
+
+_The Causes of mild Arctic Climates._--In his remarkable series of papers
+on "Ocean Currents," the late Dr. James Croll has proved, with a wealth of
+argument and illustration whose cogency is irresistible, that the very
+habitability of our globe is due to the equalizing climatic effects of the
+waters of the ocean; and that it is to the same cause that we owe, either
+directly or indirectly, almost all the chief diversities of climate between
+places situated in the same latitude. Owing to the peculiar distribution of
+land and sea upon the globe, more than its fair proportion of the warm
+equatorial waters is directed towards the western shores of Europe, the
+result being that the British Isles, Norway, and Spitzbergen, have all a
+milder climate than any other parts of the globe in corresponding
+latitudes. A very small portion of the Arctic regions, however, obtains
+this benefit, and it thus remains, generally speaking, a land of snow and
+ice, with too short a summer to nourish more than a very scanty and
+fugitive vegetation. The only other opening than that between Iceland and
+Britain by which warm water penetrates within the Arctic circle, is through
+Behring's Straits; but this is both shallow and limited in width, and the
+consequence is that the larger part of the warm currents of the Pacific
+turns back along the shores of the Aleutian Islands and North-west America,
+while a very small quantity enters the icy ocean.
+
+But if there were other and wider openings into the Arctic Ocean, a vast
+quantity of the heated water which is now turned backward would enter it,
+and would produce an amelioration of the climate of which we can hardly
+form a conception. A great amelioration of climate would also be caused by
+the breaking up or the lowering of such {80} Arctic highlands as now favour
+the accumulation of ice; while the interpenetration of the sea into any
+part of the great continents in the tropical or temperate zones would again
+tend to raise the winter temperature, and render any long continuance of
+snow in their vicinity almost impossible.
+
+Now geologists have proved, quite independently of any such questions as we
+are here discussing, that changes of the very kinds above referred to have
+occurred during the Tertiary period; and that there has been, speaking
+broadly, a steady change from a comparatively fragmentary and insular
+condition of the great north temperate lands in early Tertiary times, to
+that more compact and continental condition which now prevails. It is, no
+doubt, difficult and often impossible to determine how long any particular
+geographical condition lasted, or whether the changes in one country were
+exactly coincident with those in another; but it will be sufficient for our
+purpose briefly to indicate those more important changes of land and sea
+during the Tertiary period, which must have produced a decided effect on
+the climate of the northern hemisphere.
+
+_Geographical Changes Favouring Mild Northern Climates in Tertiary
+Times._--The distribution of the Eocene and Miocene formations shows, that
+during a considerable portion of the Tertiary period, an inland sea, more
+or less occupied by an archipelago of islands, extended across Central
+Europe between the Baltic and the Black and Caspian Seas, and thence by
+narrower channels south-eastward to the valley of the Euphrates and the
+Persian Gulf, thus opening a communication between the North Atlantic and
+the Indian Oceans. From the Caspian also a wide arm of the sea extended
+during some part of the Tertiary epoch northwards to the Arctic Ocean, and
+there is nothing to show that this sea may not have been in existence
+during the whole Tertiary period. Another channel probably existed over
+Egypt[21] into the eastern {81} basin of the Mediterranean and the Black
+Sea; while it is probable that there was a communication between the Baltic
+and the White Sea, leaving Scandinavia as an extensive island. Turning to
+India, we find that an arm of the sea of great width and depth extended
+from the Bay of Bengal to the mouths of the Indus; while the enormous
+depression indicated by the presence of marine fossils of Eocene age at a
+height of 10,500 feet in Western Tibet, renders it not improbable that a
+more direct channel across Afghanistan may have opened a communication
+between the West Asiatic and Polar seas.
+
+It may be said that the changes here indicated are not warranted by an
+actual knowledge of continuous Tertiary deposits over the situations of the
+alleged marine channels; but it is no less certain that the seas in which
+any particular strata were deposited were _always_ more extensive than the
+fragments of those strata now existing, and _often_ immensely more
+extensive. The Eocene deposits of Europe, for example, have certainly
+undergone enormous denudation both marine and subaërial, and may have once
+covered areas where we now find older deposits (as the chalk once covered
+the weald), while a portion of them may lie concealed under Miocene,
+Pliocene, or recent beds. We find them widely scattered over Europe and
+Asia, and often elevated into lofty mountain ranges; and we should
+certainly err far more seriously in confining the Eocene seas to the exact
+areas where we now find Eocene rocks, than in liberally extending them, so
+as to connect the several detached portions of the formation whenever there
+is no valid argument against our doing so. Considering then, that some one
+or more of the sea-communications here indicated almost certainly existed
+during Eocene and Miocene times, let us endeavour to estimate the probable
+effect such communications would have upon the climate of the northern
+hemisphere.
+
+_The Indian Ocean as a Source of Heat in Tertiary Times._--If we compare
+the Indian Ocean with the South Atlantic we shall see that the position and
+outline of the former are very favourable for the accumulation of a large
+body of warm water moving northwards. Its southern {82} opening between
+South Africa and Australia is very wide, and the tendency of the
+trade-winds would be to concentrate the currents towards its north-western
+extremity, just where the two great channels above described formed an
+outlet to the northern seas. As will be shown in our nineteenth chapter,
+there was probably, during the earlier portion of the Tertiary period at
+least, several large islands in the space between Madagascar and South
+India; but these had wide and deep channels between them, and their
+existence may have been favourable to the conveyance of heated water
+northward, by concentrating the currents, and thus producing massive bodies
+of moving water analogous to the Gulf Stream of the Atlantic.[22] Less heat
+would thus be lost by evaporation and radiation in the tropical zone, and
+an impulse would be acquired which would carry the warm water into the
+north polar area. About the same period Australia was probably divided into
+two islands, separated by a wide channel in a north and south direction
+(see Chapter XXII.), and through this another current would almost
+certainly set northwards, and be directed to the north-west by the southern
+extension of Malayan Asia. The more insular condition at this period of
+Australia, India, and North Africa, with the depression and probable
+fertility of the Central Asiatic plateau, would lead to the Indian Ocean
+being traversed by regular trade-winds instead of by variable monsoons, and
+thus the constant _vis a tergo_, which is so efficient in the Atlantic,
+would keep up a steady and powerful current towards the northern parts of
+the Indian Ocean, and thence through the midst of the European archipelago
+to the northern seas.
+
+Now it is quite certain that such a condition as we have here sketched out
+would produce a wonderful effect on the climate of Central Europe and
+Western and Northern Asia. Owing to the warm currents being concentrated in
+inland seas instead of being dispersed over a wide ocean like the {83}
+North Atlantic, much more heat would be conveyed into the Arctic Ocean, and
+this would altogether prevent the formation of ice on the northern shores
+of Asia, which continent did not then extend nearly so far north and was
+probably deeply inter-penetrated by the sea. This open ocean to the north,
+and the warm currents along all the northern lands, would so equalise
+temperature, that even the northern parts of Europe might then have enjoyed
+a climate fully equal to that of the warmer parts of New Zealand at the
+present day, and might have well supported the luxuriant vegetation of the
+Miocene period, even without any help from similar changes in the western
+hemisphere.[23]
+
+_Condition of North America during the Tertiary Period._--But changes of a
+somewhat similar character have also taken place in America and the
+Pacific. An enormous area west of the Mississippi, extending over much of
+the Rocky Mountains, consists of marine Cretaceous beds 10,000 feet thick,
+indicating great and long-continued subsidence, and an insular condition of
+Western America with a sea probably extending northwards to the Arctic
+Ocean. As marine Tertiary deposits are found conformably overlying these
+Cretaceous strata, Professor Dana is of opinion that the great elevation of
+this part of America did not begin till early Tertiary times. Other
+Tertiary beds in California, Alaska, Kamschatka, the Mackenzie River, the
+Parry Islands, and Greenland, indicate partial submergence {84} of all
+these lands with the possible influx of warm water from the Pacific; and
+the considerable elevation of some of the Miocene beds in Greenland and
+Spitzbergen renders it probable that these countries were then much less
+elevated, in which case only their higher summits would be covered with
+perpetual snow, and no glaciers would descend to the sea.
+
+In the Pacific there was probably an elevation of land counterbalancing, to
+some extent, the great depression of so much of the northern continents.
+Our map in Chapter XV. shows the islands that would be produced by an
+elevation of the great shoals under a thousand fathoms deep, and it is seen
+that these all trend in a south-east and north-west direction, and would
+thus facilitate the production of definite currents impelled by the
+south-east trades towards the north-west Pacific, where they would gain
+access to the polar seas through Behring's Straits, which were, perhaps,
+sometimes both wider and deeper than at present.
+
+_Effect of these Changes on the Climate of the Arctic Regions._--These
+various changes of sea and land, all tending towards a transference of heat
+from the equator to the north temperate zone, were not improbably still
+further augmented by the existence of a great inland South American sea
+occupying what are now the extensive valleys of the Amazon and Orinoco, and
+forming an additional reservoir of super-heated water to add to the supply
+poured into the North Atlantic.
+
+It is not of course supposed that all the modifications here indicated
+co-existed at the same time. We have good reason to believe, from the known
+distribution of animals in the Tertiary period, that land-communications
+have at times existed between Europe or Asia and North America, either by
+way of Behring's Straits, or by Iceland, Greenland, and Labrador. But the
+same evidence shows that these land-communications were the exception
+rather than the rule, and that they occurred only at long intervals and for
+short periods, so as at no time to bring about anything like a complete
+interchange of the productions of the two continents.[24] We may therefore
+admit that the {85} communication between the tropical and Arctic oceans
+was occasionally interrupted in one or other direction; but if we look at a
+globe instead of a Mercator's chart of the world, we shall see that the
+disproportion between the extent of the polar and tropical seas is so
+enormous that a single wide opening, with an adequate impulse to carry in a
+considerable stream of warm water, would be amply sufficient for the
+complete abolition of polar snow and ice, when aided by the absence of any
+great areas of high land within the polar circle, such high land being, as
+we have seen, essential to the production of perpetual snow even at the
+present time.
+
+Those who wish to understand the effect of oceanic currents in conveying
+heat to the north temperate and polar regions, should study the papers of
+Dr. Croll already referred to. But the same thing is equally well shown by
+the facts of the actual distribution of heat due to the Gulf Stream. The
+difference between the mean annual temperatures of the opposite coasts of
+Europe and America is well known and has been already quoted, but the
+difference of their mean _winter_ temperature is still more striking, and
+it is this which concerns us as more especially affecting the distribution
+of vegetable and animal life. Our mean winter temperature in the west of
+England is the same as that of the Southern United States, as well as that
+of Shanghai in China, both about twenty degrees of latitude further south;
+and as we go northward the difference increases, so that the winter climate
+of Nova Scotia in Lat. 45° is found within the Arctic circle on the coast
+of Norway; and if the latter country did not consist almost wholly of
+precipitous snow-clad mountains, it would be capable of supporting most of
+the vegetable products of the American coast in the latitude of
+Bordeaux.[25]
+
+{86}
+
+With these astounding facts before us, due wholly to the transference of a
+portion of the warm currents of the Atlantic to the shores of Europe, even
+with all the disadvantages of an icy sea to the north-east and ice-covered
+Greenland to the north-west, how can we doubt the enormously greater effect
+of such a condition of things as has been shown to have existed during the
+Tertiary epoch? Instead of _one_ great stream of warm water spreading
+widely over the North Atlantic and thus losing the greater part of its
+store of heat _before_ it reaches the Arctic seas, we should have _several_
+streams conveying the heat of far more extensive tropical oceans by
+comparatively narrow inland channels, thus being able to transfer a large
+proportion of their heat _into_ the northern and Arctic seas. The heat that
+they gave out during the passage, instead of being widely dispersed by
+winds and much of it lost in the higher atmosphere, would directly
+ameliorate the climate of the continents they passed through, and prevent
+all accumulation of snow except on the loftiest mountains. The formation of
+ice in the Arctic seas would then be impossible; and the mild winter
+climate of the latitude of North {87} Carolina, which by the Gulf Stream is
+transferred 20° northwards to our islands, might certainly, under the
+favourable conditions which prevailed during the Cretaceous, Eocene, and
+Miocene periods, have been carried another 20° north to Greenland and
+Spitzbergen; and this would bring about exactly the climate indicated by
+the fossil Arctic vegetation. For it must be remembered that the Arctic
+summers are, even now, really hotter than ours, and if the winter's cold
+were abolished and all ice-accumulation prevented, the high northern lands
+would be able to support a far more luxuriant summer vegetation than is
+possible in our unequal and cloudy climate.[26]
+
+_Effect of High Excentricity on the Warm Polar Climates._--If the
+explanation of the cause of the glacial epoch given in the last chapter is
+a correct one, it will, I believe, follow that changes in the amount of
+excentricity will produce no important alteration of the climates of the
+temperate and Arctic zones so long as favourable geographical conditions,
+such as have been now sketched out, render the accumulation of ice
+impossible. The effect of a high excentricity in producing a glacial epoch
+was shown to be due to the capacity of snow and ice for storing up cold,
+and its singular power (when in large masses) of preserving itself unmelted
+under a hot sun by itself causing the interposition of a protective
+covering of cloud and vapour. But mobile currents of water have no such
+power of {88} accumulating and storing up heat or cold from one year to
+another, though they do in a pre-eminent degree possess the power of
+equalising the temperature of winter and summer and of conveying the
+superabundant heat of the tropics to ameliorate the rigour of the Arctic
+winters. However great was the difference between the amount of heat
+received from the sun in winter and summer in the Arctic zone during a
+period of high excentricity and winter in _aphelion_, the inequality would
+be greatly diminished by the free ingress of warm currents to the polar
+area; and if this was sufficient to prevent any accumulation of ice, the
+summers would be warmed to the full extent of the powers of the sun during
+the long polar day, which is such as to give the pole at midsummer actually
+more heat during the twenty-four hours than the equator receives during its
+day of twelve hours. The only difference, then, that would be directly
+produced by the changes of excentricity and precession would be, that the
+summers would be at one period almost tropical, at the other of a more mild
+and uniform temperate character; while the winters would be at one time
+somewhat longer and colder, but never, probably, more severe than they are
+now in the west of Scotland.
+
+But though high excentricity would not directly modify the mild climates
+produced by the state of the northern hemisphere which prevailed during
+Cretaceous, Eocene, and Miocene times, it might indirectly affect it by
+increasing the mass of Antarctic ice, and thus increasing the force of the
+trade-winds and the resulting northward-flowing warm currents. Now there
+are many peculiarities in the distribution of plants and of some groups of
+animals in the southern hemisphere, which render it almost certain that
+there has sometimes been a greater extension of the Antarctic lands during
+Tertiary times; and it is therefore not improbable that a more or less
+glaciated condition may have been a long persistent feature of the southern
+hemisphere, due to the peculiar distribution of land and sea which favours
+the production of ice-fields and glaciers. And as we have seen that during
+the last three million years the excentricity has been almost always much
+higher than {89} it is now, we should expect that the quantity of ice in
+the southern hemisphere will usually have been greater, and will thus have
+tended to increase the force of those oceanic currents which produce the
+mild climates of the northern hemisphere.
+
+_Evidences of Climate in the Secondary and Palæozoic Epochs._--We have
+already seen, that so far back as the Cretaceous period there is the most
+conclusive evidence of the prevalence of a very mild climate not only in
+temperate but also in Arctic lands, while there is no proof whatever, or
+even any clear indication, of early glacial epochs at all comparable in
+extent and severity with that which has so recently occurred; and we have
+seen reason to connect this state of things with a distribution of land and
+sea highly favourable to the transference of warm water from equatorial to
+polar latitudes. So far as we can judge by the plant-remains of our own
+country, the climate appears to have been almost tropical in the Lower
+Eocene period; and as we go further back we find no clear indications of a
+higher, but often of a lower temperature, though always warmer or more
+equable than our present climate. The abundant corals and reptiles of the
+Oolite and Lias indicate equally tropical conditions; but further back, in
+the Trias, the flora and fauna, in the British area, become poorer, and
+there is nothing incompatible with a climate no warmer than that of the
+Upper Miocene. This poverty is still more marked in the Permian formation,
+and it is here that some indications of ice-action are found in the Lower
+Permian conglomerates of the west of England. These beds contain abundant
+fragments of various rocks, often angular and sometimes weighing half a
+ton, while others are partially rounded, and have polished and striated
+surfaces, just like the stones of the "till." They lie confusedly bedded in
+a red unstratified marl, and some of them can be traced to the Welsh hills
+from twenty to fifty miles distant. This remarkable formation was first
+pointed out as proving a remote glacial period, by Professor Ramsay; and
+Sir Charles Lyell agreed that this is the only possible explanation that,
+with our present knowledge, we can give of them.
+
+Permian breccias are also found in Ireland, containing {90} blocks of
+Silurian and Old Red sandstone rocks which Professor Hull believes could
+only have been carried by floating ice. Similar breccias occur in the south
+of Scotland, and these are stated to be "overlain by a deposit of glacial
+age, so similar to the breccia below as to be with difficulty distinguished
+from it."[27]
+
+These numerous physical indications of ice-action over a considerable area
+during the same geological period, coinciding with just such a poverty of
+organic remains as might be produced by a very cold climate, are very
+important, and seem clearly to indicate that at this remote period
+geographical conditions were such as to bring about a glacial epoch, or
+perhaps only local glaciation, in our part of the world.
+
+Boulder-beds also occur in the Carboniferous formation, both in Scotland,
+on the continent of Europe, and in North America; and Professor Dawson
+considers that he has detected true glacial deposits of the same age in
+Nova Scotia. Boulder-beds also occur in the Silurian rocks of Scotland and
+North America, and according to Professor Dawson, even in the Huronian,
+older than our Cambrian. None of these indications are however so
+satisfactory as those of Permian age, where we have the very kind of
+evidence we looked for in vain throughout the whole of the Tertiary and
+Secondary periods. Its presence in several localities in such ancient rocks
+as the Permian is not only most important as indicating a glacial epoch of
+some kind in Palæozoic times, but confirms us in the validity of our
+conclusion, that the _total_ absence of any such evidence throughout the
+Tertiary and Secondary epochs demonstrates the absence of recurring glacial
+epochs in the northern hemisphere, notwithstanding the frequent recurrence
+of periods of high excentricity.
+
+_Warm Arctic Climates in Early Secondary and Palæozoic Times._--The
+evidence we have already adduced of the mild climates prevailing in the
+Arctic regions throughout the Miocene, Eocene, and Cretaceous periods is
+supplemented by a considerable body of facts relating to still earlier
+epochs.
+
+{91}
+
+In the Jurassic period, for example, we have proofs of a mild Arctic
+climate, in the abundant plant-remains of East Siberia and Amurland, with
+less productive deposits in Spitzbergen, and at Ando in Norway just within
+the Arctic circle. But even more remarkable are the marine remains found in
+many places in high northern latitudes, among which we may especially
+mention the numerous ammonites and the vertebræ of huge reptiles of the
+genera Ichthyosaurus and Teleosaurus found in the Jurassic deposits of the
+Parry Islands in 77° N. Lat.
+
+In the still earlier Triassic age, nautili and ammonites inhabited the seas
+of Spitzbergen, where their fossil remains are now found.
+
+In the Carboniferous formation we again meet with plant-remains and beds of
+true coal in the Arctic regions. Lepidodendrons and Calamites, together
+with large spreading ferns, are found at Spitzbergen, and at Bear Island in
+the extreme north of Eastern Siberia; while marine deposits of the same age
+contain abundance of large stony corals.
+
+Lastly, the ancient Silurian limestones, which are widely spread in the
+high Arctic regions, contain abundance of corals and cephalopodous mollusca
+resembling those from the same deposits in more temperate lands.
+
+_Conclusions as to the Climates of Tertiary and Secondary Periods._--If now
+we look at the whole series of geological facts as to the animal and
+vegetable productions of the Arctic regions in past ages, it is certainly
+difficult to avoid the conclusion that they indicate a climate of a
+uniformly temperate or warm character. Whether in Miocene, Upper or Lower
+Cretaceous, Jurassic, Triassic, Carboniferous or Silurian times, and in all
+the numerous localities extending over more than half the polar regions, we
+find one uniform climatic aspect in the fossils. This is quite inconsistent
+with the theory of alternate cold and mild epochs during phases of high
+excentricity, and persistent cold epochs when the excentricity was as low
+as it is now or lower, for that would imply that the duration of cold
+conditions was _greater_ than that of warm. Why then should the fauna and
+flora of the cold epochs _never_ be {92} preserved? Mollusca and many other
+forms of life are abundant in the Arctic seas, and there is often a
+luxuriant dwarf woody vegetation on the land, yet in no one case has a
+single example of such a fauna or flora been discovered of a date anterior
+to the last glacial epoch. And this argument is very much strengthened when
+we remember that an exactly analogous series of facts is found over all the
+temperate zones. Everywhere we have abundant floras and faunas indicating
+warmer conditions than such as now prevail, but never in a single instance
+one which as clearly indicates colder conditions. The fact that drift with
+Arctic shells was deposited during the last glacial epoch, as well as
+gravels and crag with the remains of arctic animals and plants, shows us
+that there is nothing to prevent such deposits being formed in cold as well
+as in warm periods; and it is quite impossible to believe that in every
+place and at all epochs all records of the former have been destroyed,
+while in a considerable number of instances those of the latter have been
+preserved. When to this uniform testimony of the palæontological evidence
+we add the equally uniform absence of any indication of those ice-borne
+rocks, boulders, and drift, which are the constant and necessary
+accompaniment of every period of glaciation, and which must inevitably
+pervade all the marine deposits formed over a wide area so long as the
+state of glaciation continues, we are driven to the conclusion that the
+last glacial epoch of the northern hemisphere was exceptional, and was not
+preceded by numerous similar glacial epochs throughout Tertiary and
+Secondary time.
+
+But although glacial epochs (with the one or two exceptions already
+referred to) were certainly absent, considerable changes of climate may
+have frequently occurred, and these would lead to important changes in the
+organic world. We can hardly doubt that some such change occurred between
+the Lower and Upper Cretaceous periods, the floras of which exhibit such an
+extraordinary contrast in general character. We have also the testimony of
+Mr. J. S. Gardner, who has long worked at the fossil floras of the Tertiary
+deposits, and who states, that {93} there is strong negative and some
+positive evidence of alternating warmer and colder conditions, not glacial,
+contained not only in English Eocene, but all Tertiary beds throughout the
+world.[28] In the case of marine faunas it is more difficult to judge, but
+the numerous changes in the fossil remains from bed to bed only a few feet
+and sometimes a few inches apart, may be sometimes due to change of
+climate; and when it is recognised that such changes have probably occurred
+at all geological epochs and their effects are systematically searched for,
+many peculiarities in the distribution of organisms through the different
+members of one deposit may be traced to this cause.
+
+_General View of Geological Climates as dependent on the Physical Features
+of the Earth's Surface._--In the preceding chapters I have earnestly
+endeavoured to arrive at an explanation of geological climates in the
+temperate and Arctic zones, which should be in harmony with the great body
+of geological facts now available for their elucidation. If my conclusions
+as here set forth diverge considerably from those of Dr. Croll, it is not
+from any want of appreciation of his facts and arguments, since for many
+years I have upheld and enforced his views to the best of my ability. But a
+careful re-examination of the whole question has now convinced me that an
+error has been made in estimating the comparative effect of geographical
+and astronomical causes on changes of climate, and that, while the latter
+have undoubtedly played an important part in bringing about the glacial
+epoch, it is to the former that the mild climates of the Arctic regions are
+almost entirely due. If I have now succeeded in approaching to a true
+solution of this difficult problem, I owe it mainly to the study of Dr.
+Croll's writings, since my theory is entirely based on the facts and
+principles so clearly set forth in his admirable papers on "Ocean Currents
+in relation to the Distribution of Heat over the Globe." The main features
+of this theory as distinct from that of Dr. Croll I will now endeavour to
+summarise.
+
+Looking at the subject broadly, we see that the climatic {94} condition of
+the northern hemisphere is the result of the peculiar distribution of land
+and water upon the globe; and the general permanence of the position of the
+continental and oceanic areas--which we have shown to be proved by so many
+distinct lines of evidence--is also implied by the general stability of
+climate throughout long geological periods. The land surface of our earth
+appears to have always consisted of three great masses in the north
+temperate zone, narrowing southward, and terminating in three comparatively
+narrow extremities represented by Southern America, South Africa, and
+Australia. Towards the north these masses have approached each other, and
+have sometimes become united; leaving beyond them a considerable area of
+open polar sea. Towards the south they have never been much further
+prolonged than at present, but far beyond their extremities an extensive
+mass of land has occupied the south polar area.
+
+This arrangement is such as would cause the northern hemisphere to be
+always (as it is now) warmer than the southern, and this would lead to the
+preponderance of northward winds and ocean currents, and would bring about
+the concentration of the latter in three great streams carrying warmth to
+the north-polar regions. These streams would, as Dr. Croll has so well
+shown, be greatly increased in power by the glaciation of the south polar
+land; and whenever any considerable portion of this land was elevated, such
+a condition of glaciation would certainly be brought about, and would be
+heightened whenever a high degree of excentricity prevailed.
+
+It is now the general opinion of geologists that the great continents have
+undergone a process of development from earlier to later times. Professor
+Dana appears to have been the first who taught it explicitly in the case of
+the North American continent, and he has continued the development of his
+views from 1856, when he discussed the subject in the _American Journal_,
+to the later editions of his _Manual of Geology_ in which the same views
+are extended to all the great continents. He says:--
+
+"The North American continent, which since early {95} time had been
+gradually expanding in each direction from the northern Azoic, eastward,
+westward, and southward, and which, after the Palæozoic, was finished in
+its rocky foundation, excepting on the borders of the Atlantic and Pacific
+and the area of the Rocky Mountains, had reached its full expansion at the
+close of the Tertiary period. The progress from the first was uniform and
+systematic: the land was at all times simple in outline; and its
+enlargement took place with almost the regularity of an exogenous
+plant."[29]
+
+A similar development undoubtedly took place in the European area, which
+was apparently never so compact and so little interpenetrated by the sea as
+it is now, while Europe and Asia have only become united into one unbroken
+mass since late Tertiary times.
+
+If, however, the greater continents have become more compact and massive
+from age to age, and have received their chief extensions northward at a
+comparatively recent period, while the Antarctic lands had a corresponding
+but somewhat earlier development, we have all the conditions requisite to
+explain the persistence, with slight fluctuations, of warm climates far
+into the north-polar area throughout Palæozoic, Mesozoic, and Tertiary
+times. At length, during the latter part of the Tertiary epoch, a
+considerable elevation took place, closing up several of the water passages
+to the north, and raising up extensive areas in the Arctic regions to
+become the receptacle of snow and ice-fields. This elevation is indicated
+by the abundance of Miocene and the absence of Pliocene deposits in the
+Arctic zone and the considerable altitude of many Miocene rocks in Europe
+and North America; and the occurrence at this time of a long-continued
+period of high excentricity necessarily brought on the glacial epoch in the
+manner already described in our last chapter. A depression seems to have
+occurred during the glacial period itself in North America as in Britain,
+but this may have been due partly to the weight of the ice and partly to a
+rise of the ocean {96} level caused by the earth's centre of gravity being
+shifted towards the north.
+
+We thus see that the last glacial epoch was the climax of a great process
+of continental development which had been going on throughout long
+geological ages; and that it was the direct consequence of the north
+temperate and polar land having attained a great extension and a
+considerable altitude just at the time when a phase of very high
+excentricity was coming on. Throughout earlier Tertiary and Secondary times
+an equally high excentricity often occurred, but it never produced a
+glacial epoch, because the north temperate and polar areas had less high
+land, and were more freely open to the influx of warm oceanic currents. But
+wherever great plateaux with lofty mountains occurred in the temperate zone
+a considerable _local_ glaciation might be produced, which would be
+specially intense during periods of high excentricity; and it is to such
+causes we must impute the indications of ice-action in the vicinity of the
+Alps during the Tertiary period. The Permian glaciation appears to have
+been more extensive, and it is quite possible that at this remote epoch a
+sufficient mass of high land existed in our area and northwards towards the
+pole, to have brought on a true glacial period comparable with that which
+has so recently passed away.
+
+_Estimate of the comparative effects of Geographical and Astronomical
+Causes in producing Changes of Climate._--It appears then, that while
+geographical and physical causes alone, by their influence on ocean
+currents, have been the main agents in producing the mild climates which
+for such long periods prevailed in the Arctic regions, the concurrence of
+astronomical causes--high excentricity with winter in _aphelion_--was
+necessary to the production of the great glacial epoch. If we reject this
+latter agency, we shall be obliged to imagine a concurrence of geographical
+changes at a very recent period of which we have no evidence. We must
+suppose, for example, that a large part of the British Isles--Scotland,
+Ireland, and Wales at all events--were simultaneously elevated so as to
+bring extensive areas above the line of perpetual snow; that {97} about the
+same time Scandinavia, the Alps, and the Pyrenees received a similar
+increase of altitude; and that, almost simultaneously, Eastern North
+America, the Sierra Nevada of California, the Caucasus, Lebanon, the
+southern mountains of Spain, the Atlas range, and the Himalayas, were each
+some thousands of feet higher than they are now; for all these mountains
+present us with indications of a recent extension of their glaciers, in
+superficial phenomena so similar to those which occur in our own country
+and in Western Europe, that we cannot suppose them to belong to a different
+epoch. Such a supposition is rendered more difficult by the general
+concurrence of scientific testimony to a partial submergence during the
+glacial epoch, not only in all parts of Britain, but in North America,
+Scandinavia, and, as shown by the wide extension of the drift, in Northern
+Europe; and when to this we add the difficulty of understanding how any
+probable addition to the altitude of our islands could have brought about
+the extreme amount of glaciation which they certainly underwent, and when,
+further, we know that a phase of very high excentricity did occur at a
+period which is generally admitted to agree well with physical evidence of
+the time elapsed since the cold passed away, there seems no sufficient
+reason why such an agency should be ignored.
+
+No doubt a prejudice has been excited against it in the minds of many
+geologists, by its being thought to lead _necessarily_ to frequently
+recurring glacial epochs throughout all geological time. But I have here
+endeavoured to show that this is _not_ a necessary consequence of the
+theory, because a concurrence of favourable geographical conditions is
+essential to the initiation of a glaciation, which when once initiated has
+a tendency to maintain itself throughout the varying phases of precession
+occurring during a period of high excentricity. When, however, geographical
+conditions favour warm Arctic climates--as it has been shown they have done
+throughout the larger portion of geological time--then changes of
+excentricity, to however great an extent, have no tendency to bring about a
+state of glaciation, because warm oceanic currents have a {98}
+preponderating influence, and without very large areas of high northern
+land to act as condensers, no perpetual snow is possible, and hence the
+initial process of glaciation does not occur.
+
+The theory as now set forth should commend itself to geologists, since it
+shows the direct dependence of climate on physical processes, which are
+guided and modified by those changes in the earth's surface which geology
+alone can trace out. It is in perfect accord with the most recent teachings
+of the science as to the gradual and progressive development of the earth's
+crust from the rudimentary formations of the Azoic age, and it lends
+support to the view that no inportant[**important] departure from the great
+lines of elevation and depression originally marked out on the earth's
+surface has ever taken place.
+
+It also shows us how important an agent in the production of a habitable
+globe with comparatively small extremes of climates over its whole area, is
+the great disproportion between the extent of the land and the water
+surfaces. For if these proportions had been reversed, large areas of land
+would necessarily have been removed from the beneficial influence of
+aqueous currents or moisture-laden winds; and slight geological changes
+might easily have led to half the land surface becoming covered with
+perpetual snow and ice, or being exposed to extremes of summer heat and
+winter cold, of which our water-permeated globe at present affords no
+example. We thus see that what are usually regarded as geographical
+anomalies--the disproportion of land and water, the gathering of the land
+mainly into one hemisphere, and the singular arrangement of the land in
+three great southward-pointing masses--are really facts of the greatest
+significance and importance, since it is to these very anomalies that the
+universal spread of vegetation and the adaptability of so large a portion
+of the earth's surface for human habitation is directly due.
+
+ * * * * *
+
+
+{99}
+
+CHAPTER X
+
+THE EARTH'S AGE, AND THE RATE OF DEVELOPMENT OF ANIMALS AND PLANTS
+
+ Various Estimates of Geological Time--Denudation and Deposition of
+ Strata as a Measure of Time--How to Estimate the Thickness of the
+ Sedimentary Rocks--How to Estimate the Average Rate of Deposition of
+ the Sedimentary Rocks--The Rate of Geological Change Probably greater
+ in very Remote Times--Value of the Preceding Estimate of Geological
+ Time--Organic Modification Dependent on Change of
+ Conditions--Geographical Mutations as a Motive Power in bringing about
+ Organic Changes--Climatal Revolutions as an Agent in Producing Organic
+ Changes--Present Condition of the Earth one of Exceptional Stability as
+ Regards Climate--Date of last Glacial Epoch and its Bearing on the
+ Measurement of Geological Time--Concluding Remarks.
+
+The subjects discussed in the last three chapters introduce us to a
+difficulty which has hitherto been considered a very formidable one--that
+the maximum age of the habitable earth, as deduced from physical
+considerations, does not afford sufficient time either for the geological
+or the organic changes of which we have evidence. Geologists continually
+dwell on the slowness of the processes of upheaval and subsidence, of
+denudation of the earth's surface, and of the formation of new strata;
+while on the theory of development, as expounded by Mr. Darwin, the
+variation and modification of organic forms is also a very slow process,
+and has usually been considered to require an {100} even longer series of
+ages than might satisfy the requirements of physical geology alone.
+
+As an indication of the periods usually contemplated by geologists, we may
+refer to Sir Charles Lyell's calculation in the tenth edition of his
+_Principles of Geology_ (omitted in later editions), by which he arrived at
+240 millions of years as having probably elapsed since the Cambrian
+period--a very moderate estimate in the opinion of most geologists. This
+calculation was founded on the rate of modification of the species of
+mollusca; but much more recently Professor Haughton has arrived at nearly
+similar figures from a consideration of the rate of formation of rocks and
+their known maximum thickness, whence he deduces a maximum of 200 millions
+of years for the whole duration of geological time, as indicated by the
+series of stratified formations.[30] But in the opinion of all our first
+naturalists and geologists, the period occupied in the formation of the
+known stratified rocks only represents a portion, and perhaps a small
+portion, of geological time. In the sixth edition of the _Origin of
+Species_ (p. 286), Mr. Darwin says: "Consequently, if the theory be true,
+it is indisputable that before the lowest Cambrian stratum was deposited
+long periods elapsed, as long as, or probably far longer than, the whole
+interval from the Cambrian age to the present day; and that during these
+vast periods the world swarmed with living creatures." Professor Huxley, in
+his anniversary address to the Geological Society in 1870, adduced a number
+of special cases showing that, on the theory of development, almost all the
+higher forms of life must have existed during the Palæozoic period. Thus,
+from the fact that almost the whole of the Tertiary period has been
+required to convert the ancestral Orohippus into the true horse, he
+believes that, in order to have time for the much greater change of the
+ancestral Ungulata into the two great odd-toed and even-toed divisions (of
+which change there is no trace even among the earliest Eocene mammals), we
+should require a large portion, if not the whole, of the Mesozoic or
+Secondary period. Another case is furnished by the bats and whales, both of
+which strange modifications of the {101} mammalian type occur perfectly
+developed in the Eocene formation. What countless ages back must we then go
+for the origin of these groups, the whales from some ancestral carnivorous
+animal, and the bats from the insectivora! And even then we have to seek
+for the common origin of carnivora, insectivora, ungulata, and marsupials
+at a far earlier period; so that, on the lowest estimate, we must place the
+origin of the mammalia very far back in Palæozoic times. Similar evidence
+is afforded by reptiles, of which Professor Huxley says: "If the very small
+differences which are observable between the crocodiles of the older
+Secondary formations and those of the present day furnish any sort of an
+approximation towards an estimate of the average rate of change among
+reptiles, it is almost appalling to reflect how far back in Palæozoic times
+we must go before we can hope to arrive at that common stock from which the
+crocodiles, lizards, _Ornithoscelida_, and _Plesiosauria_, which had
+attained so great a development in the Triassic epoch, must have been
+derived." Professor Ramsay has expressed similar views, derived from a
+general study of the whole series of geological formations and their
+contained fossils. He says, speaking of the abundant, varied, and
+well-developed fauna of the Cambrian period: "In this earliest known
+_varied_ life we find no evidence of its having lived near the beginning of
+the zoological series. In a broad sense, compared with what must have gone
+before, both biologically and physically, all the phenomena connected with
+this old period seem, to my mind, to be of quite a recent description; and
+the climates of seas and lands were of the very same kind as those the
+world enjoys at the present day."[31]
+
+These opinions, and the facts on which they are founded, are so weighty,
+that we can hardly doubt that, if the time since the Cambrian epoch is
+correctly estimated at 200 millions of years, the date of the commencement
+of life on the earth cannot be much less than 500 millions; while it may
+not improbably have been longer, because the reaction of {102} the organism
+under changes of the environment is believed to have been less active in
+low and simple, than in high and complex forms of life, and thus the
+processes of organic development may for countless ages have been
+excessively slow.
+
+But according to the physicists, no such periods as are here contemplated
+can be granted. From a consideration of the possible sources of the heat of
+the sun, as well as from calculations of the period during which the earth
+can have been cooling to bring about the present rate of increase of
+temperature as we descend beneath the surface, Sir William Thomson
+concludes that the crust of the earth cannot have been solidified much
+longer than 100 million years (the maximum possible being 400 millions),
+and this conclusion is held by Dr. Croll and other men of eminence to be
+almost indisputable.[32] It will therefore be well to consider on what data
+the calculations of geologists have been founded, and how far the views
+here set forth, as to frequent changes of climate throughout all geological
+time, may affect the rate of biological change.
+
+_Denudation and Deposition of Strata as a Measure of Time._--The materials
+of all the stratified rocks of the globe have been obtained from the dry
+land. Every point of the surface is exposed to the destructive influences
+of sun and wind, frost, snow, and rain, which break up and wear away the
+hardest rocks as well as the softer deposits, and by means of rivers convey
+the worn material to the sea. The existence of a considerable depth of soil
+over the greater part of the earth's surface; of vast heaps of rocky
+_débris_ at the foot of every inland cliff; of enormous deposits of gravel,
+sand, and loam; as well as the shingle, pebbles, sand or mud, of every
+sea-shore, alike attest the universality of this destructive agency. It is
+no less clearly shown by the way in which almost every drop of running
+water--whether in gutter, brooklet, stream or large river--becomes
+discoloured after each heavy rainfall, since the matter which causes this
+discolouration must be derived from the surface {103} of the country, must
+always pass from a higher to a lower level, and must ultimately reach the
+sea, unless it is first deposited in some lake, or by the overflowing of a
+river goes to form an alluvial plain. The universality of this subaërial
+denudation, both as regards space and time, renders it certain that its
+cumulative effects must be very great; but no attempt seems to have been
+made to determine the magnitude of these effects till Mr. Alfred Tylor, in
+1853,[33] pointed out that by measuring the quantity of solid matter
+brought down by rivers (which can be done with considerable accuracy), we
+may obtain the amount of lowering of the land-area, and also the rise of
+the ocean level, owing to the quantity of matter deposited on its floor. A
+few years later Dr. Croll applied the same method in more detail to an
+estimate of the amount by which the land is lowered in a given period; and
+the validity of this method has been upheld by Sir A. Geikie, Sir Charles
+Lyell, and all our best geologists, as affording a means of actually
+determining with some approach to accuracy, the time occupied by one
+important phase of geological change.
+
+The quantity of matter carried away from the land by a river is greater
+than at first sight appears, and is more likely to be under- than
+over-estimated. By taking samples of water near the mouth of a river (but
+above the influence of the tide) at a sufficient number of points in its
+channel and at different depths, and repeating this daily or at other short
+intervals throughout the year, it is easy to determine the quantity of
+solid matter held in suspension and solution; and if corresponding
+observations determine the quantity of water that is discharged, the total
+amount of solid matter brought down annually may be calculated. But besides
+this, a considerable quantity of sand or even gravel is carried along the
+bottom or bed of the river, and this has rarely been estimated, so that the
+figures hitherto obtained are usually under the real quantities. There is
+also another source of error caused by the quantity of matter the river may
+deposit in lakes or in flooded lands during its course, for this adds to
+the amount of denudation performed by the river, although {104} the matter
+so deposited does not come down to the sea. After a careful examination of
+all the best records, Sir A. Geikie arrives at the following results, as to
+the quantity of matter removed by seven rivers from their basins, estimated
+by the number of years required to lower the whole surface an average of
+one foot:
+
+ The Mississippi removes one foot in 6,000 years.
+ ,, Ganges ,, ,, 2,358 ,,
+ ,, Hoang Ho ,, ,, 1,464 ,,
+ ,, Rhone ,, ,, 1,528 ,,
+ ,, Danube ,, ,, 6,846 ,,
+ ,, Po ,, ,, 729 ,,
+ ,, Nith ,, ,, 4,723 ,,
+
+Here we see an intelligible relation between the character of the river
+basin and the amount of denudation. The Mississippi has a large portion of
+its basin in an arid country, and its sources are either in forest-clad
+plateaux or in mountains free from glaciers and with a scanty rainfall. The
+Danube flows through Eastern Europe where the rainfall is considerably less
+than in the west, while comparatively few of its tributaries rise among the
+loftiest Alps. The proportionate amounts of denudation being then what we
+might expect, and as all are probably under rather than over the truth, we
+may safely take the average of them all as representing an amount of
+denudation which, if not true for the whole land surface of the globe, will
+certainly be so for a very considerable proportion of it. This average is
+almost exactly one foot in three thousand years.[34] The mean altitude of
+the several {105} continents has been recently estimated by Mr. John
+Murray,[35] to be as follows: Europe 939 feet, Asia 3,189 feet, Africa 2020
+feet, North America 1,888 feet, and South America 2,078 feet. At the rate
+of denudation above given, it results that, were no other forces at work,
+Europe would be planed down to the sea-level in about two million eight
+hundred thousand years; while if we take a somewhat slower rate for North
+America, that continent might last about four or five million years.[36]
+This also implies that the mean height of these continents would have been
+about double what it is now three million and five million years ago
+respectively: and as we have no reason to suppose this to have been the
+case, we are led to infer the constant action of that upheaving force which
+the presence of sedimentary formations even on the highest mountains also
+demonstrates.
+
+We have already discussed the unequal rate of denudation on hills, valleys,
+and lowlands, in connection with the evidence of remote glacial epochs (p.
+173); what we have now to consider is, what becomes of all this denuded
+matter, and how far the known rate of denudation affords us a measure of
+the rate of deposition, and thus gives us some indication of the lapse of
+geological time from a comparison of this rate with the observed thickness
+of stratified rocks on the earth's surface.
+
+{106}
+
+_How to Estimate the Thickness of the Sedimentary Rocks._--The sedimentary
+rocks of which the earth's crust is mainly composed consist, according to
+Sir Charles Lyell's classification, of fourteen great formations, of which
+the most ancient is the Laurentian, and the most recent the Post-Tertiary
+or Pleistocene; with thirty important subdivisions, each of which again
+consists of a more or less considerable number of distinct beds or strata.
+Thus, the Silurian formation is divided into Upper and Lower Silurian, each
+characterized by a distinct set of fossil remains, and the Upper Silurian
+again consists of a large number of separate beds, such as the Wenlock
+Limestone, the Upper Llandovery Sandstone the Lower Llandovery Slates, &c.,
+each usually characterised by a difference of mineral composition or
+mechanical structure, as well as by some peculiar fossils. These beds and
+formations vary greatly in extent, both above and beneath the surface, and
+are also of very various thicknesses in different localities. A thick bed
+or series of beds often thins out in a given direction, and sometimes
+disappears altogether, so that two beds which were respectively above and
+beneath it may come into contact. As an example of this thinning out,
+American geologists adduce the Palæozoic formations of the Appalachian
+Mountains, which have a total thickness of 42,000 feet, but as they are
+traced westward thin out till they become only 4,000 feet in total
+thickness. In like manner the Carboniferous grits and shales are 18,000
+feet thick in Yorkshire and Lancashire, but they thin out southwards, so
+that in Leicestershire they are only 3,000 feet thick; and similar
+phenomena occur in all strata and in every part of the world. It must be
+observed that this thinning out has nothing to do with denudation (which
+acts upon the surface of a country so as to produce great irregularities of
+contour), but is a regular attenuation of the layers of rock, due to a
+deficiency of sediment in certain directions at the original formation of
+the deposit. Owing to this thinning out of stratified rocks, they are on
+the whole of far less extent than is usually supposed. When we see a
+geological map showing successive formations following each other in long
+irregular belts across the country (as is well {107} seen in the case of
+the Secondary rocks of England), and a corresponding section showing each
+bed dipping beneath its predecessor, we are apt to imagine that beneath the
+uppermost bed we should find all the others following in succession like
+the coats of an onion. But this is far from being the case, and a
+remarkable proof of the narrow limitation of these formations has been
+recently obtained by a boring at Ware through the Chalk and Gault Clay,
+which latter immediately rests on the Upper Silurian Wenlock Limestone full
+of characteristic fossils, at a depth of only 800 feet. Here we have an
+enormous gap, showing that none of earlier Secondary or late Palæozoic
+formations extend to this part of England, unless indeed they had been all
+once elevated and entirely swept away by denudation.[37]
+
+But if we consider how such deposits are now forming, we shall find that
+the thinning out of the beds of each formation, and their restriction to
+irregular bands and patches, is exactly what we should expect. The enormous
+quantity of sediment continually poured into the sea by rivers, gradually
+subsides to the bottom as soon as the motion of the water is checked. All
+the heavier material must be deposited near the shore or in those areas
+over which it is first spread by the tides or currents of the ocean; while
+only the very fine mud and clay is carried out to considerable distances.
+Thus all stratified deposits {108} will form most quickly near the shores,
+and will thin out rapidly at greater distances, little or none being formed
+in the depths of the great oceans. This important fact was demonstrated by
+the specimens of sea-bottom examined during the voyage of the _Challenger_,
+all the "shore deposits" being usually confined within a distance of 100 or
+150 miles from the coast; while the "deep-sea deposits" are either purely
+organic, being formed of the calcareous or siliceous skeletons of
+globigerinæ, radiolarians, and diatomaceæ, or are clays formed of
+undissolved portions of these, together with the disintegrated or dissolved
+materials of pumice and volcanic dust, which being very light are carried
+by wind or by water over the widest oceans.
+
+From the preceding considerations we shall be better able to appreciate the
+calculations as to the thickness of stratified deposits made by geologists.
+Professor Ramsay has calculated that the sedimentary rocks of Britain alone
+have a total _maximum_ thickness of 72,600 feet; while Professor Haughton,
+from a survey of the whole world, estimates the _maximum_ thickness of the
+known stratified rocks at 177,200 feet. Now these _maximum_ thicknesses of
+each deposit will have been produced only where the conditions were
+exceptionally favourable, either in deep water near the mouths of great
+rivers, or in inland seas, or in places to which the drainage of extensive
+countries was conveyed by ocean currents; and this great thickness will
+necessarily be accompanied by a corresponding thinness, or complete absence
+of deposit, elsewhere. How far the series of rocks found in any extensive
+area, as Europe or North America, represents the whole series of deposits
+which have been made there we cannot tell; but there is no reason to think
+that it is a very inadequate representation of their _maximum_ thickness,
+though it undoubtedly is of their _extent_ and _bulk_. When we see in how
+many distinct localities patches of the same formation occur, it seems
+improbable that the whole of the deposits formed during any one period
+should have been destroyed, even in such an area as Europe, while it is
+still more improbable that they should be so destroyed over the whole
+world; and {109} if any considerable portion of them is left, that portion
+may give a fair idea of their average, or even of their maximum, thickness.
+In his admirable paper on "The Mean Thickness of the Sedimentary
+Rocks,"[38] Dr. James Croll has dwelt on the extent of denudation in
+diminishing the mean thickness of the rocks that have been formed,
+remarking, "Whatever the present mean thickness of all the sedimentary
+rocks of our globe may be, it must be small in comparison to the mean
+thickness of all the sedimentary rocks which have been formed. This is
+obvious from the fact that the sedimentary rocks of one age are partly
+formed from the destruction of the sedimentary rocks of former ages. From
+the Laurentian age down to the present day the stratified rocks have been
+undergoing constant denudation." This is perfectly true, and yet the mean
+thickness of that portion of the sedimentary rocks which remains may not be
+very different from that of the entire mass, because denudation acts only
+on those rocks which are exposed on the surface of a country, and most
+largely on those that are upheaved; while, except in the rare case of an
+extensive formation being _quite horizontal_, and wholly exposed to the sea
+or to the atmosphere, denudation can have no tendency to diminish the
+thickness of any entire deposit.[39] Unless, therefore, a formation is
+completely destroyed by denudation in every part of the world (a thing very
+improbable), we may have in existing rocks a not very inadequate
+representation of the _mean thickness_ of all that have been formed, and
+even of the _maximum_ thickness of the larger portion. This will be the
+more likely because it is almost certain that many rocks contemporaneously
+formed are counted by geologists as distinct formations, whenever they
+differ in lithological character or in organic remains. But we know that
+limestones, sandstones, and shales, are always forming at the same time;
+{110} while a great difference in organic remains may arise from
+comparatively slight changes of geographical features, or from difference
+in the depth or purity of the water in which the animals lived.[40]
+
+_How to Estimate the Average Rate of Deposition of the Sedimentary
+Rocks._--But if we take the estimate of Professor Haughton (177,200 feet),
+which, as we have seen, is probably excessive, for the maximum thickness of
+the sedimentary rocks of the globe of all known geological ages, can we
+arrive at any estimate of the rate at which they were formed? Dr. Croll has
+attempted to make such an estimate, but he has taken for his basis the
+_mean_ thickness of the rocks, which we have no means whatever of arriving
+at, and which he guesses, allowing for denudation, to be equal to the
+_maximum_ thickness as measured by geologists. The land-area of the globe
+is, according to Dr. Croll, 57,000,000[41] square miles, and he gives the
+coast-line as 116,000 miles. This, however, is, for our purpose, rather too
+much, as it allows for bays, inlets, and the smaller islands. An
+approximate measurement on a globe shows that 100,000 miles will be nearer
+the mark, and this has the advantage of being an easily remembered even
+number. The distance from the coast, to which shore-deposits usually
+extend, may be reckoned at about 100 or 150 miles, but by far the larger
+portion of the matter brought down from the land will be deposited
+comparatively close to the shore; that is, within twenty or thirty miles.
+If we suppose the portion deposited beyond thirty miles to be added to the
+deposits within that distance, and the whole reduced to a uniform thickness
+in a direction at right angles to the coast, we should probably include all
+areas where deposits of the maximum thickness {111} are forming at the
+present time, along with a large but unknown proportion of surface where
+the deposits were far below the maximum thickness. This follows, if we
+consider that deposit must go on very unequally along different parts of a
+coast, owing to the distance from each other of the mouths of great rivers
+and the limitations of ocean currents; and because, compared with the areas
+over which a thick deposit is forming annually, those where there is little
+or none are probably at least twice as extensive. If, therefore, we take a
+width of thirty miles along the whole coast-line of the globe as
+representing the area over which deposits are forming, corresponding to the
+maximum thickness as measured by geologists, we shall certainly over rather
+than under-estimate the possible rate of deposit.[42]
+
+Now a coast line of 100,000 miles with a width of 30 gives an area of
+3,000,000 square miles, on which the denuded matter of the whole land-area
+of 57,000,000 square {112} miles is deposited. As these two areas are as 1
+to 19, it follows that deposition, as measured by _maximum_ thickness, goes
+on at least nineteen times as fast as denudation--probably very much
+faster. But the mean rate of denudation over the whole earth is about one
+foot in three thousand years; therefore the rate of maximum deposition will
+be at least 19 feet in the same time; and as the total maximum thickness of
+all the stratified rocks of the globe is, according to Professor Haughton,
+177,200 feet, the time required to produce this thickness of rock, at the
+present rate of denudation and deposition, is only 28,000,000 years.[43]
+
+_The Rate of Geological Change Probably Greater in very Remote Times._--The
+opinion that denudation and deposition went on more rapidly in earlier
+times owing to the frequent occurrence of vast convulsions and cataclysms
+was strenuously opposed by Sir Charles Lyell, who so well showed that
+causes of the very same nature as those now in action were sufficient to
+account for all the phenomena presented by the rocks throughout the whole
+series of geological formations. But while upholding the soundness of the
+views of the "uniformitarians" as opposed to the "convulsionists," we must
+yet admit that there is reason for believing in a gradually increasing
+intensity of all telluric action as we go back into past time. This subject
+has been well treated by Mr. W. J. Sollas,[44] who shows that, if, as all
+physicists maintain, the sun gave out perceptibly more heat in past ages
+than now, this alone would cause an increase in almost all the forces that
+have brought about geological phenomena. With greater heat there would be a
+more extensive aqueous atmosphere, and, perhaps, a greater difference
+between equatorial and polar temperatures; hence more violent winds,
+heavier rains and snows, {113} and more powerful oceanic currents, all
+producing more rapid denudation. At the same time, the internal heat of the
+earth being greater, it would be cooling more rapidly, and thus the forces
+of contraction--which cause the upheaving of mountains, the eruption of
+volcanoes, and the subsidence of extensive areas--would be more powerful
+and would still further aid the process of denudation. Yet again, the
+earth's rotation was certainly more rapid in very remote times, and this
+would cause more impetuous tides and still further add to the denuding
+power of the ocean. It thus appears that, as we go back into the past,
+_all_ the forces tending to the continued destruction and renewal of the
+earth's surface would be in more powerful action, and must therefore tend
+to reduce the time required for the deposition and upheaval of the various
+geological formations. It may be true, as many geologists assert, that the
+changes here indicated are so slow that they would produce comparatively
+little effect within the time occupied by the known sedimentary rocks, yet,
+whatever effect they did produce would certainly be in the direction here
+indicated, and as several causes are acting together, their combined
+effects may have been by no means unimportant. It must also be remembered
+that such an increase of the primary forces on which all geologic change
+depends would act with great effect in still further intensifying those
+alternations of cold and warm periods in each hemisphere, or, more
+frequently, of excessive and equable seasons, which have been shown to be
+the result of astronomical, combined with geographical, revolutions; and
+this would again increase the rapidity of denudation and deposition, and
+thus still further reduce the time required for the production of the known
+sedimentary rocks. It is evident therefore that these various
+considerations all combine to prove that, in supposing that the rate of
+denudation has been on the average only what it is now, we are almost
+certainly over-estimating the _time_ required to have produced the whole
+series of formations from the Cambrian upwards.
+
+_Value of the Preceding Estimate of Geological Time._--It is not of course
+supposed that the calculation here given {114} makes any approach to
+accuracy, but it is believed that it does indicate the _order_ of magnitude
+of the time required. We have a certain number of data, which are not
+guessed but the result of actual measurement; such are, the amount of solid
+matter carried down by rivers, the width of the belt within which this
+matter is mainly deposited, and the maximum thickness of the known
+stratified rocks.[45] A considerable but unknown amount of denudation is
+effected by the waves of the ocean eating away coast lines. This was once
+thought to be of more importance than sub-aërial denudation, but it is now
+believed to be comparatively slow in its action.[46] Whatever it may be,
+however, it adds to the rate of formation of new strata, and its omission
+from the calculation is again on the side of making the lapse of time
+greater rather than less than the true amount. Even if a considerable
+modification should be needed in some of the assumptions it has been
+necessary to make, the result must still show that, so far as the time
+required for the formation of the known stratified rocks, the hundred
+million years allowed by physicists is not only ample, but will permit of
+even more than an equal period anterior to the lowest Cambrian rocks, as
+demanded by Mr. Darwin--a demand supported and enforced by the arguments,
+taken from independent standpoints, of Professor Huxley and Professor
+Ramsay.
+
+_Organic Modification Dependent on Change of Conditions._--Having {115}
+thus shown that the physical changes of the earth's surface may have gone
+on much more rapidly and occupied much less time than has generally been
+supposed, we have now to inquire whether there are any considerations which
+lead to the conclusion that organic changes may have gone on with
+corresponding rapidity.
+
+There is no part of the theory of natural selection which is more clear and
+satisfactory than that which connects changes of specific forms with
+changes of external conditions or environment. If the external world
+remains for a moderate period unchanged, the organic world soon reaches a
+state of equilibrium through the struggle for existence; each species
+occupies its place in nature, and there is then no inherent tendency to
+change. But almost any change whatever in the external world disturbs this
+equilibrium, and may set in motion a whole series of organic revolutions
+before it is restored. A change of climate in any direction will be sure to
+injure some and benefit other species. The one will consequently diminish,
+the other increase in number; and the former may even become extinct. But
+the extinction of a species will certainly affect other species which it
+either preyed upon, or competed with, or served for food; while the
+increase of any one animal may soon lead to the extinction of some other to
+which it was inimical. These changes will in their turn bring other
+changes; and before an equilibrium is again established, the proportions,
+ranges, and numbers, of the species inhabiting the country may be
+materially altered. The complex manner in which animals are related to each
+other is well exhibited by the importance of insects, which in many parts
+of the world limit the numbers or determine the very existence of some of
+the higher animals. Mr. Darwin says:--"Perhaps Paraguay offers the most
+curious instance of this; for here neither cattle, nor horses, nor dogs
+have ever run wild, though they swarm southward and northward in a wild
+state; and Azara and Rengger have shown that this is caused by the greater
+number in Paraguay of a certain fly, which lays its eggs in the navels of
+these animals when first born. The increase of these flies, numerous as
+they are, must be {116} habitually checked by some means, probably by other
+parasitic insects. Hence, if certain insectivorous birds were to decrease
+in Paraguay, the parasitic insects would probably increase; and this would
+lessen the number of navel-frequenting flies--then cattle and horses would
+run wild; and this would certainly alter (as indeed I have observed in
+parts of South America) the vegetation: this again would largely affect the
+insects, and this, as we have seen in Staffordshire, the insectivorous
+birds, and so onwards in ever increasing circles of complexity."
+
+Geographical changes would be still more important, and it is almost
+impossible to exaggerate the modifications of the organic world that might
+result from them. A subsidence of land separating a large island from a
+continent would affect the animals and plants in a variety of ways. It
+would at once modify the climate, and so produce a series of changes from
+this cause alone; but more important would be its effect by isolating small
+groups of individuals of many species and thus altering their relations to
+the rest of the organic world. Many of these would at once be exterminated,
+while others, being relieved from competition, might flourish and become
+modified into new species. Even more striking would be the effects when two
+continents, or any two land areas which had been long separated, were
+united by an upheaval of the strait which divided them. Numbers of animals
+would now be brought into competition for the first time. New enemies and
+new competitors would appear in every part of the country; and a struggle
+would commence which, after many fluctuations, would certainly result in
+the extinction of some species, the modification of others, and a
+considerable alteration in the proportionate numbers and the geographical
+distribution of almost all.
+
+Any other changes which led to the intermingling of species whose ranges
+were usually separate would produce corresponding results. Thus, increased
+severity of winter or summer temperature, causing southward migrations and
+the crowding together of the productions of distinct regions, must
+inevitably produce a struggle for existence, which would lead to many
+changes both in the characters and {117} the distribution of animals. Slow
+elevations of the land would produce another set of changes, by affording
+an extended area in which the more dominant species might increase their
+numbers; and by a greater range and variety of alpine climates and mountain
+stations, affording room for the development of new forms of life.
+
+_Geographical Mutations as a Motive Power in Bringing about Organic
+Changes._--Now, if we consider the various geographical changes which, as
+we have seen, there is good reason to believe have ever been going on in
+the world, we shall find that the motive power to initiate and urge on
+organic changes has never been wanting. In the first place, every
+continent, though permanent in a general sense, has been ever subject to
+innumerable physical and geographical modifications. At one time the total
+area has increased, and at another has diminished; great plateaus have
+gradually risen up, and have been eaten out by denudation into mountain and
+valley; volcanoes have burst forth, and, after accumulating vast masses of
+eruptive matter, have sunk down beneath the ocean, to be covered up with
+sedimentary rocks, and at a subsequent period again raised above the
+surface; and the _loci_ of all these grand revolutions of the earth's
+surface have changed their position age after age, so that each portion of
+every continent has again and again been sunk under the ocean waves, formed
+the bed of some inland sea, or risen high into plateaus and mountain
+ranges. How great must have been the effects of such changes on every form
+of organic life! And it is to such as these we may perhaps trace those
+great changes of the animal world which have seemed to revolutionise it,
+and have led us to class one geological period as the age of reptiles,
+another as the age of fishes, and a third as the age of mammals.
+
+But such changes as these must necessarily have led to repeated unions and
+separations of the land masses of the globe, joining together continents
+which were before divided, and breaking up others into great islands or
+extensive archipelagoes. Such alterations of the means of transit would
+probably affect the organic world even more profoundly than the changes of
+area, of altitude, or {118} of climate, since they afforded the means, at
+long intervals, of bringing the most diverse forms into competition, and of
+spreading all the great animal and vegetable types widely over the globe.
+But the isolation of considerable masses of land for long periods also
+afforded the means of preservation to many of the lower types, which thus
+had time to become modified into a variety of distinct forms, some of which
+became so well adapted to special modes of life that they have continued to
+exist to the present day, thus affording us examples of the life of early
+ages which would probably long since have become extinct had they been
+always subject to the competition of the more highly organised animals. As
+examples of such excessively archaic forms, we may mention the mud-fishes
+and the ganoids, confined to limited fresh-water areas; the frogs and
+toads, which still maintain themselves vigorously in competition with
+higher forms; and among mammals the Ornithorhynchus and Echidna of
+Australia; the whole order of Marsupials--which, out of Australia, where
+they are quite free from competition, only exist abundantly in South
+America, which was certainly long isolated from the northern continents;
+the Insectivora, which, though widely scattered, are generally nocturnal or
+subterranean in their habits; and the Lemurs, which are most abundant in
+Madagascar, where they have long been isolated, and almost removed from the
+competition of higher forms.
+
+_Climatal Revolutions as an Agent in Producing Organic Changes._--The
+geographical and geological changes we have been considering are probably
+those which have been most effective in bringing about the great features
+of the distribution of animals, as well as the larger movements in the
+development of organised beings; but it is to the alternations of warm and
+cold, or of uniform and excessive climates--of almost perpetual spring in
+arctic as well as in temperate lands, with occasional phases of cold
+culminating at remote intervals in glacial epochs,--that we must impute
+some of the more remarkable changes both in the specific characters and in
+the distribution of organisms.[47] {119} Although the geological evidence
+is opposed to the belief in early glacial epochs except at very remote and
+distant intervals, there is nothing which contradicts the occurrence of
+repeated changes of climate, which, though too small in amount to produce
+any well-marked physical or organic change, would yet be amply sufficient
+to keep the organic world in a constant state of movement, and which, by
+subjecting the whole flora and fauna of a country at comparatively short
+intervals to decided changes of physical conditions, would supply that
+stimulus and motive power which, as we have seen, is all that is necessary
+to keep the processes of "natural selection" in constant operation.
+
+The frequent recurrence of periods of high and of low excentricity must
+certainly have produced changes of climate of considerable importance to
+the life of animals and plants. During periods of high excentricity with
+summer in _perihelion_, that season would be certainly very much hotter,
+while the winters would be longer and colder than at present; and although
+geographical conditions might prevent any permanent increase of snow and
+ice even in the extreme north, yet we cannot doubt that the whole northern
+hemisphere would then have a very different climate than when the changing
+phase of precession brought a very cool summer and a very mild winter--a
+perpetual spring, in fact. Now, such a change of climate would certainly be
+calculated to bring about a considerable change of _species_, both by
+modification and migration, without any such decided change of _type_
+either in the vegetation or the animals that we could say from their fossil
+remains that any change of climate had taken place. Let us suppose, for
+instance, that the climate of England and that of Canada were to be
+mutually exchanged, and that the change took five or six thousand years to
+bring about, it cannot be doubted that considerable modifications in the
+fauna and flora of both countries would be the result, although it is
+impossible to predict {120} what the precise changes would be. We can
+safely say, however, that some species would stand the change better than
+others, while it is highly probable that some would be actually benefited
+by it, and that others would be injured. But the benefited would certainly
+increase, and the injured decrease, in consequence, and thus a series of
+changes would be initiated that might lead to most important results.
+Again, we are sure that some species would become modified in adaptation to
+the change of climate more readily than others, and these modified species
+would therefore increase at the expense of others not so readily modified;
+and hence would arise on the one hand extinction of species, and on the
+other the production of new forms.
+
+But this is the very least amount of change of climate that would certainly
+occur every 10,500 years when there was a high excentricity, for it is
+impossible to doubt that a varying distance of the sun in summer from 86 to
+99 millions of miles (which is what occurred during--as supposed--the
+Miocene period, 850,000 years ago) would produce an important difference in
+the summer temperature and in the actinic influence of sunshine on
+vegetation. For the intensity of the sun's rays would vary as the square of
+the distance, or nearly as 74 to 98, so that the earth would be actually
+receiving one-fourth less sun-heat during summer at one time than at the
+other. An equally high excentricity occurred 2,500,000 years back, and no
+doubt was often reached during still earlier epochs, while a lower but
+still very high excentricity has frequently prevailed, and is probably near
+its average value. Changes of climate, therefore, every 10,500 years, of
+the character above indicated and of varying intensity, have been the rule
+rather than the exception in past time; and these changes must have been
+variously modified by changing geographical conditions so as to produce
+climatic alterations in different directions, giving to the ancient lands
+either dry or wet seasons, storms or calms, equable or excessive
+temperatures, in a variety of combinations of which the earth perhaps
+affords no example under the present low phase of {121} excentricity and
+consequent slight inequality of sun-heat.
+
+_Present Condition of the Earth One of Exceptional Stability as Regards
+Climate._--It will be seen, by a reference to the diagram at page 171, that
+during the last three million years the excentricity has been _less_ than
+it is now on eight occasions, for short periods only, making up a total of
+about 280,000 years; while it has been _more_ than it is now for many long
+periods, of from 300,000 to 700,000 years each, making a total of 2,720,000
+years; or nearly as 10 to 1. For nearly half the entire period, or
+1,400,000 years, the excentricity has been nearly double what it is now,
+and this is not far from its mean condition. We have no reason for
+supposing that this long period of three million years, for which we have
+tables, was in any way exceptional as regards the degree or variation of
+excentricity; but, on the contrary, we may pretty safely assume that its
+variations during this time fairly represent its average state of increase
+and decrease during all known geological time. But when the glacial epoch
+ended, 72,000 years ago, the excentricity was about double its present
+amount; it then rapidly decreased till, at 60,000 years back, it was very
+little greater than it is now, and since then it has been uniformly small.
+It follows that, for about 60,000 years before our time, the mutations of
+climate every 10,500 years have been comparatively unimportant, and that
+the temperate zones have enjoyed _an exceptional stability of climate_.
+During this time those powerful causes of organic change which depend on
+considerable changes of climate and the consequent modifications,
+migrations, and extinctions of species, will not have been at work; the
+slight changes that did occur would probably be so slow and so little
+marked that the various species would be able to adapt themselves to them
+without much disturbance; and the result would be _an epoch of exceptional
+stability of species_.
+
+But it is from this very period of _exceptional stability_ that we obtain
+our only _scale_ for measuring the rate of organic change. It includes not
+only the historical period, {122} but that of the Swiss Lake dwellings, the
+Danish shell-mounds, our peat-bogs, our sunken forests, and many of our
+superficial alluvial deposits--the whole in fact, of the iron, bronze, and
+neolithic ages. Even some portion of the palæolithic age, and of the more
+recent gravels and cave-earths may come into the same general period if
+they were formed when the glacial epoch was passing away. Now throughout
+all these ages we find no indication of change of species, and but little,
+comparatively, of migration. We thus get an erroneous idea of _the
+permanence and stability of specific forms_, due to the period immediately
+antecedent to our own being a _period of exceptional permanence and
+stability_ as regards climatic and geographical conditions.[48]
+
+_Date of Last Glacial Epoch and its Bearing on the Measurement of
+Geological Time._--Directly we go back from this stable period we come upon
+changes both in the forms and in the distribution of species; and when we
+pass beyond the last glacial epoch into the Pliocene period we find
+ourselves in a comparatively new world, surrounded by a considerable number
+of species altogether different from any which now exist, together with
+many others which, though still living, now inhabit distant regions. It
+seems not improbable that what is termed the Pliocene period, was really
+the coming on of the glacial epoch, and this is the opinion of Professor
+Jules Marcou.[49] According to our views, a considerable amount of
+geographical change must have occurred at the change from the Miocene to
+the Pliocene, favouring the refrigeration of the northern hemisphere, and
+leading, in the way already pointed out, to the glacial epoch whenever a
+high degree of excentricity {123} prevailed. As many reasons combine to
+make us fix the height of the glacial epoch at the period of high
+excentricity which occurred 200,000 years back, and as the Pliocene period
+was probably not of long duration, we must suppose the next great phase of
+very high excentricity (850,000 years ago) to fall within the Miocene
+epoch. Dr. Croll believes that this must have produced a glacial period,
+but we have shown strong reasons for believing that, in concurrence with
+favourable geographical conditions, it led to uninterrupted warm climates
+in the temperate and northern zones. This, however, did not prevent the
+occurrence of local glaciation wherever other conditions led to its
+initiation, and the most powerful of such conditions is a great extent of
+high land. Now we know that the Alps acquired a considerable part of their
+elevation during the latter part of the Miocene period, since Miocene rocks
+occur at an elevation of over 6,000 feet, while Eocene beds occur at nearly
+10,000 feet. But since that time there has been a vast amount of
+denudation, so that these rocks may have been at first raised much higher
+than we now find them, and thus a considerable portion of the Alps may have
+been more elevated than they are now. This would certainly lead to an
+enormous accumulation of snow, which would be increased when the
+excentricity reached a maximum, as already fully explained, and may then
+have caused glaciers to descend into the adjacent sea, carrying those
+enormous masses of rock which are buried in the Upper Miocene of the
+Superga in Northern Italy. An earlier epoch of great altitude in the Alps
+coinciding with the very high excentricity 2,500,000 years ago, may have
+caused the local glaciation of the Middle Eocene period when the enormous
+erratics of the Flysch conglomerate were deposited in the inland seas of
+Northern Switzerland, the Carpathians, and the Apennines. This is quite in
+harmony with the indications of an uninterrupted warm climate and rich
+vegetation during the very same period in the adjacent low countries, just
+as we find at the present day in New Zealand a delightful climate and a
+rich vegetation of Metrosideros, {124} fuchsias and tree-ferns on the very
+borders of huge glaciers, descending to within 700 feet of the sea-level.
+It is not pretended that these estimates of geological time have any more
+value than probable guesses; but it is certainly a curious coincidence that
+two remarkable periods of high excentricity should have occurred, at such
+periods and at such intervals apart, as very well accord with the
+comparative remoteness of the two deposits in which undoubted signs of
+ice-action have been found, and that both these are localised in the
+vicinity of mountains which are known to have acquired a considerable
+elevation at about the same period of time.
+
+In the tenth edition of the _Principles of Geology_, Sir Charles Lyell,
+taking the amount of change in the species of mollusca as a guide,
+estimated the time elapsed since the commencement of the Miocene as
+one-third that of the whole Tertiary epoch, and the latter at one-fourth
+that of geological time since the Cambrian period. Professor Dana, on the
+other hand, estimates the Tertiary as only one-fifteenth of the Mesozoic
+and Palæozoic combined. On the estimate above given, founded on the dates
+of phases of high excentricity, we shall arrive at about four million years
+for the Tertiary epoch, and sixteen million years for the time elapsed
+since the Cambrian, according to Lyell, or sixty millions according to
+Dana. The estimate arrived at from the rate of denudation and deposition
+(twenty-eight million years) is nearly midway between these, and it is, at
+all events, satisfactory that the various measures result in figures of the
+same order of magnitude, which is all one can expect when discussing so
+difficult and exceedingly speculative a subject.
+
+The only value of such estimates is to define our notions of geological
+time, and to show that the enormous periods, of hundreds of millions of
+years, which have sometimes been indicated by geologists, are neither
+necessary nor warranted by the facts at our command; while the present
+result places us more in harmony with the calculations of physicists, by
+leaving a very wide margin between geological time as defined by the
+fossiliferous rocks, and that {125} far more extensive period which
+includes all possibility of life upon the earth.
+
+_Concluding Remarks._--In the present chapter I have endeavoured to show
+that, combining the measured rate of denudation with the estimated
+thickness and probable extent of the known series of sedimentary rocks, we
+may arrive at a rude estimate of the time occupied in the formation of
+those rocks. From another point of departure--that of the probable date of
+the Miocene period, as determined by the epoch of high excentricity
+supposed to have aided in the production of the Alpine glaciation during
+that period, and taking the estimate of geologists as to the proportionate
+amount of change in the animal world since that epoch--we obtain another
+estimate of the duration of geological time, which, though founded on far
+less secure data, agrees pretty nearly with the former estimate. The time
+thus arrived at is immensely less than the usual estimates of geologists,
+and is so far within the limits of the duration of the earth as calculated
+by Sir William Thomson, as to allow for the development of the lower
+organisms an amount of time anterior to the Cambrian period several times
+greater than has elapsed between that period and the present day. I have
+further shown that, in the continued mutations of climate produced by high
+excentricity and opposite phases of precession, even though these did not
+lead to glacial epochs, we have a motive power well calculated to produce
+far more rapid organic changes than have hitherto been thought possible;
+while in the enormous amount of specific variation (as demonstrated in an
+earlier chapter), we have ample material for that power to act upon, so as
+to keep the organic world in a state of rapid change and development
+proportioned to the comparatively rapid changes in the earth's surface.
+
+
+
+We have now finished the series of preliminary studies of the biological
+conditions and physical changes which have affected the modification and
+dispersal of organisms, and have thus brought about their actual
+distribution on {126} the surface of the earth. These studies will, it is
+believed, place us in a condition to solve most of the problems presented
+by the distribution of animals and plants, whenever the necessary facts,
+both as to their distribution and their affinities, are sufficiently well
+known; and we now proceed to apply the principles we have established to
+the interpretation of the phenomena presented by some of the more important
+and best known of the islands of our globe, limiting ourselves to these for
+reasons which have been already sufficiently explained in our preface.
+
+ * * * * *
+
+
+PART II
+
+_INSULAR FAUNAS AND FLORAS_
+
+{241}
+
+CHAPTER XI
+
+THE CLASSIFICATION OF ISLANDS
+
+ Importance of Islands in the Study of the Distribution of
+ Organisms--Classification of Islands with Reference to
+ Distribution--Continental Islands--Oceanic Islands.
+
+In the preceding chapters, forming the first part of our work, we have
+discussed, more or less fully, the general features presented by animal
+distribution, as well as the various physical and biological changes which
+have been the most important agents in bringing about the present condition
+of the organic world.
+
+We now proceed to apply these principles to the solution of the numerous
+problems presented by the distribution of animals; and in order to limit
+the field of our inquiry, and at the same time to deal only with such facts
+as may be rendered intelligible and interesting to those readers who have
+not much acquaintance with the details of natural history, we propose to
+consider only such phenomena as are presented by the islands of the globe.
+
+_Importance of Islands in the Study of the Distribution of
+Organisms._--Islands possess many advantages for the study of the laws and
+phenomena of distribution. As compared with continents they have a
+restricted area and definite boundaries, and in most cases their
+geographical and biological limits coincide. The number of species and of
+genera they contain is always much smaller than in the {242} case of
+continents, and their peculiar species and groups are usually well defined
+and strictly limited in range. Again, their relations with other lands are
+often direct and simple, and even when more complex are far easier to
+comprehend than those of continents; and they exhibit besides certain
+influences on the forms of life and certain peculiarities in their
+distribution which continents do not present, and whose study offers many
+points of interest.
+
+In islands we have the facts of distribution presented to us, sometimes in
+their simplest forms, in other cases becoming gradually more and more
+complex; and we are therefore able to proceed step by step in the solution
+of the problems they present. But as in studying these problems we have
+necessarily to take into account the relations of the insular and
+continental faunas, we also get some knowledge of the latter, and acquire
+besides so much command over the general principles which underlie all
+problems of distribution, that it is not too much to say that when we have
+mastered the difficulties presented by the peculiarities of island life we
+shall find it comparatively easy to deal with the more complex and less
+clearly defined problems of continental distribution.
+
+_Classification of Islands with Reference to Distribution._--Islands have
+had two distinct modes of origin--they have either been separated from
+continents of which they are but detached fragments, or they have
+originated in the ocean and have never formed part of a continent or any
+large mass of land. This difference of origin is fundamental, and leads to
+a most important difference in their animal inhabitants; and we may
+therefore first distinguish the two classes--oceanic and continental
+islands.
+
+Mr. Darwin appears to have been the first writer who called attention to
+the number and importance, both from a geological and biological point of
+view, of oceanic islands. He showed that with very few exceptions all the
+remoter islands of the great oceans were of volcanic or coralline
+formation, and that none of them contained indigenous mammalia or amphibia.
+He also showed the connection of these two phenomena, and maintained that
+none of the islands so characterised had ever formed {243} part of a
+continent. This was quite opposed to the opinions of the scientific men of
+the day, who almost all held the idea of continental extensions, and of
+oceanic islands being their fragments, and it was long before Mr. Darwin's
+views obtained general acceptance. Even now the belief still lingers; and
+we continually hear of old Atlantic or Pacific continents, of "Atlantis" or
+"Lemuria," of which hypothetical lands many existing islands, although
+wholly volcanic, are thought to be the remnants. We have already seen that
+Darwin connected the peculiar geological structure of oceanic islands with
+the permanence of the great oceans which contain them, and we have shown
+that several distinct lines of evidence all point to the same conclusion.
+We may therefore define oceanic islands, as follows:--Islands of volcanic
+or coralline formation, usually far from continents and always separated
+from them by very deep sea, entirely without indigenous land mammalia or
+amphibia, but with a fair number of birds and insects, and usually with
+some reptiles. This definition will exclude only two islands which have
+been sometimes classed as oceanic--New Zealand and the Seychelles.
+Rodriguez, which was once thought to be another exception, has been shown
+by the explorations during the Transit of Venus Expedition to be
+essentially volcanic, with some upraised coralline limestone.
+
+_Continental Islands._--Continental islands are always more varied in their
+geological formation, containing both ancient and recent stratified rocks.
+They are rarely very remote from a continent, and they always contain some
+land mammals and amphibia, as well as representatives of the other classes
+and orders in considerable variety. They may, however, be divided into two
+well-marked groups--ancient and recent continental islands--the characters
+of which may be easily defined.
+
+Recent continental islands are always situated on submerged banks
+connecting them with a continent, and the depth of the intervening sea
+rarely exceeds 100 fathoms. They resemble the continent in their geological
+structure, while their animal and vegetable productions are either almost
+identical with those of the continent, or if {244} otherwise, the
+difference consists in the presence of closely allied species of the same
+types, with occasionally a very few peculiar genera. They possess in fact
+all the characteristics of a portion of the continent, separated from it at
+a recent geological period.
+
+Ancient continental islands differ greatly from the preceding in many
+respects. They are not united to the adjacent continent by a shallow bank,
+but are usually separated from it by a depth of sea of several hundreds to
+more than a thousand fathoms. In geological structure they agree generally
+with the more recent islands; like them they possess mammalia and amphibia,
+usually in considerable abundance, as well as all other classes of animals;
+but these are highly peculiar, almost all being distinct species, and many
+forming distinct and peculiar genera or families. They are also well
+characterised by the fragmentary nature of their fauna, many of the most
+characteristic continental orders or families being quite unrepresented,
+while some of their animals are allied, not to such forms as inhabit the
+adjacent continent, but to others found only in remote parts of the world.
+This very remarkable set of characters marks off the islands which exhibit
+them as a distinct class, which often present the greatest anomalies and
+most difficult problems to the student of distribution.
+
+_Oceanic Islands._--The total absence of warm-blooded terrestrial animals
+in an island otherwise well suited to maintain them, is held to prove that
+such island is no mere fragment of any existing or submerged continent, but
+one that has been actually produced in mid-ocean. It is true that if a
+continental island were to be completely submerged for a single day and
+then again elevated, its higher terrestrial animals would be all destroyed,
+and if it were situated at a considerable distance from land it would be
+reduced to the same zoological condition as an oceanic island. But such a
+complete submergence and re-elevation appears never to have taken place,
+for there is no single island on the globe which has the physical and
+geological features of a continental, combined with the zoological features
+of an oceanic island. It is true that some of the coral-islands may be
+formed upon submerged lands {245} of a continental character, but we have
+no proof of this; and even if it were so, the existing islands are to all
+intents and purposes oceanic.
+
+We will now pass on to a consideration of some of the more interesting
+examples of these three classes, beginning with oceanic islands.
+
+All the animals which now inhabit such oceanic islands must either
+themselves have reached them by crossing the ocean, or be the descendants
+of ancestors who did so. Let us then see what are, in fact, the animal and
+vegetable inhabitants of these islands, and how far their presence can be
+accounted for. We will begin with the Azores, or Western Islands, because
+they have been thoroughly well explored by naturalists, and in their
+peculiarities afford us an important clue to some of the most efficient
+means of distribution among several classes of animals.
+
+ * * * * *
+
+
+{246}
+
+CHAPTER XII
+
+OCEANIC ISLANDS:--THE AZORES AND BERMUDA
+
+THE AZORES, OR WESTERN ISLANDS
+
+ Position and Physical Features--Chief Zoological Features of the
+ Azores--Birds--Origin of the Azorean Bird Fauna--Insects of the
+ Azores--Land-Shells of the Azores--The Flora of the Azores--The
+ Dispersal of Seeds--Birds as Seed-Carriers--Facilities for Dispersal of
+ Azorean Plants--Important Deduction from the Peculiarities of the
+ Azorean Fauna and Flora.
+
+BERMUDA
+
+ Position and Physical Features--The Red Clay of Bermuda--Zoology of
+ Bermuda--Birds of Bermuda--Comparison of the Bird Faunas of Bermuda and
+ the Azores--Insects of Bermuda--Land Mollusca--Flora of
+ Bermuda--Concluding Remarks on the Azores and Bermuda.
+
+We will commence our investigation into the phenomena presented by oceanic
+islands, with two groups of the North Atlantic, in which the facts are of a
+comparatively simple nature and such as to afford us a valuable clue to a
+solution of the more difficult problems we shall have to deal with further
+on. The Azores and Bermuda offer great contrasts in physical features, but
+striking similarities in geographical position. The one is volcanic, the
+other coralline; but both are surrounded by a wide expanse of ocean of
+enormous depth, the one being about as far from Europe as the other is from
+America. Both are situated in the {247} temperate zone, and they differ
+less than six degrees in latitude, yet the vegetation of the one is wholly
+temperate, while that of the other is almost tropical. The productions of
+the one are related to Europe, as those of the other are to America, but
+they present instructive differences; and both afford evidence of the
+highest value as to the means of dispersal of various groups of organisms
+across a wide expanse of ocean.
+
+THE AZORES, OR WESTERN ISLANDS.
+
+These islands, nine in number, form a widely scattered group, situated
+between 37° and 39° 40' N. Lat. and stretching in a south-east and
+north-west direction over a distance of nearly 400 miles. The largest of
+the islands, San Miguel, is about forty miles long, and is one of the
+nearest to Europe, being rather under 900 miles from the coast of Portugal,
+from which it is separated by an ocean 2,500 fathoms deep. The depth
+between the islands does not seem to be known, but the 1,000 fathom line
+encloses the whole group pretty closely, while a depth of about 1,800
+fathoms is reached within 300 miles in all directions. These great depths
+render it in the highest degree improbable that the Azores have ever been
+united with the European continent; while their being wholly volcanic is
+equally opposed to the view of their having formed part of an extensive
+Atlantis including Madeira and the Canaries. The only exception to their
+volcanic structure is the occurrence in one small island only (Santa Maria)
+of some marine deposits of Upper Miocene age--a fact which proves some
+alterations of level, and perhaps a greater extension of this island at
+some former period, but in no way indicates a former union of the islands,
+or any greater extension of the whole group. It proves, however, that the
+group is of considerable antiquity, since it must date back to Miocene
+times; and this fact may be of importance in considering the origin and
+peculiar features of the fauna and flora. It thus appears that in all
+physical features the Azores correspond strictly with our physical
+definition of "oceanic islands," while their great distance {248} from any
+other land, and the depth of the ocean around them, make them typical
+examples of the class. We should therefore expect them to be equally
+typical in their fauna and flora; and this is the case as regards the most
+important characteristics, although in some points of detail they present
+exceptional phenomena.
+
+[Illustration: OUTLINE MAP OF THE AZORES.]
+
+ NOTE.--
+ The light tint shows where the sea is less than 1,000 fathoms deep.
+ The dark tint " " " more than 1,000 fathoms deep.
+ The figures show depths in fathoms.
+
+_Chief Zoological Features of the Azores._[50]--The great feature of
+oceanic islands--the absence of all indigenous land-mammalia and
+amphibia--is well shown in this {249} group; and it is even carried
+further, so as to include all terrestrial vertebrata, there being no snake,
+lizard, frog, or fresh-water fish, although the islands are sufficiently
+extensive, possess a mild and equable climate, and are in every way adapted
+to support all these groups. On the other hand, flying creatures, as birds
+and insects, are abundant; and there is also one flying mammal--a small
+European bat. It is true that rabbits, weasels, rats and mice, and a small
+lizard peculiar to Madeira and Teneriffe, are now found wild in the Azores,
+but there is good reason to believe that these have all been introduced by
+human agency. The same may be said of the gold-fish and eels now found in
+some of the lakes, there being not a single fresh-water fish which is truly
+indigenous to the islands. When we consider that the nearest part of the
+group is about 900 miles from Portugal, and more than 550 miles from
+Madeira, it is not surprising that none of these terrestrial animals can
+have passed over such a wide expanse of ocean unassisted by man.
+
+Let us now see what animals are believed to have reached the group by
+natural means, and thus constitute its indigenous fauna. These consist of
+birds, insects, and land-shells, each of which must be considered
+separately.
+
+_Birds._--Fifty-three species of birds have been observed at the Azores,
+but the larger proportion (thirty-one) are either aquatic or waders--birds
+of great powers of flight, whose presence in the remotest islands is by no
+means remarkable. Of these two groups twenty are residents, breeding in the
+islands, while eleven are stragglers only visiting the islands
+occasionally, and all are common European species. The land-birds,
+twenty-two in number, are more interesting, four only being stragglers,
+while eighteen are permanent residents. The following is a list of these
+resident land-birds:--
+
+ 1. Common Buzzard (_Buteo vulgaris_)
+ 2. Long-eared Owl (_Asio otus_)
+ 3. Barn Owl (_Strix flammea_)
+ 4. Blackbird (_Turdus merula_)
+ 5. Robin (_Erythacus rubecula_)
+ 6. Blackcap (_Sylvia atricapilla_)
+ {250}
+ 7. Gold-crest (_Regulus cristatus_)
+ 8. Wheatear (_Saxicola oenanthe_)
+ 9. Grey Wagtail (_Motacilla sulphurea_)
+ 10. Atlantic Chaffinch (_Fringilla tintillon_)
+ 11. Azorean Bullfinch (_Pyrrhula murina_)
+ 12. Canary (_Serinus canarius_)
+ 13. Common Starling (_Sturnus vulgaris_)
+ 14. Lesser Spotted Woodpecker (_Dryobates minor_)
+ 15. Wood-pigeon (_Columba palumbus_)
+ 16. Rock Dove (_Columba livia_)
+ 17. Red-legged Partridge (_Caccabis rufa_)
+ 18. Common Quail (_Coturnix communis_)
+
+All the above-named birds are common in Europe and North Africa except
+three--the Atlantic chaffinch and the canary which inhabit Madeira and the
+Canary Islands, and the Azorean bullfinch, which is peculiar to the islands
+we are considering.
+
+_Origin of the Azorean Bird-fauna._--The questions we have now before us
+are--how did these eighteen species of birds first reach the Azores, and
+how are we to explain the presence of a single peculiar species while all
+the rest are identical with European birds? In order to answer them, let us
+first see what stragglers now actually visit the Azores from the nearest
+continents. The four species given in Mr. Godman's list are the kestrel,
+the oriole, the snow-bunting, and the hoopoe; but he also tells us that
+there are certainly others, and adds: "Scarcely a storm occurs in spring or
+autumn without bringing one or more species foreign to the islands; and I
+have frequently been told that swallows, larks, grebes, and other species
+not referred to here, are not uncommonly seen at those seasons of the
+year."
+
+We have, therefore, every reason to believe that the birds which are now
+residents originated as stragglers, which occasionally found a haven in
+these remote islands when driven out to sea by storms. Some of them, no
+doubt, still often arrive from the continent, but these cannot easily be
+distinguished as new arrivals among those which are permanent inhabitants.
+Many facts mentioned by Mr. Godman show that this is the case. A barn-owl,
+much exhausted, flew on board a whaling-ship when 500 miles S.W. of the
+Azores; and even if it had come from {251} Madeira it must have travelled
+quite as far as from Portugal to the islands. Mr. Godman also shot a single
+specimen of the wheatear in Flores after a strong gale of wind, and as no
+one on the island knew the bird, it was almost certainly a recent arrival.
+Subsequently a few were found breeding in the old crater of Corvo, a small
+adjacent island; and as the species is not found in any other island of the
+group, we may infer that this bird is a recent immigrant in process of
+establishing itself.
+
+Another fact which is almost conclusive in favour of the bird-population
+having arrived as stragglers is, that they are most abundant in the islands
+nearest to Europe and Africa. The Azores consist of three divisions--an
+eastern, consisting of two islands, St. Michael's and St. Mary's; a central
+of five, Terceira, Graciosa, St. George's, Pico, and Fayal; and a western
+of two, Flores and Corvo. Now had the whole group once been united to the
+continent, or even formed parts of one extensive Atlantic island, we should
+certainly expect the central group, which is more compact and has a much
+larger area than all the rest, to have the greatest number and variety of
+birds. But the fact that birds are most numerous in the eastern group, and
+diminish as we go westward, is entirely opposed to this theory, while it is
+strictly in accordance with the view that they are all stragglers from
+Europe, Africa, or the other Atlantic islands. Omitting oceanic wanderers,
+and including all birds which have probably arrived involuntarily, the
+numbers are found to be forty species in the eastern group, thirty-six in
+the central, and twenty-nine in the western.
+
+To account for the presence of one peculiar species--the bullfinch (which,
+however, does not differ from the common European bullfinch more than do
+some of the varieties of North American birds from their type-species) is
+not difficult; the wonder rather being that there are not more peculiar
+forms. In our third chapter we have seen how great is the amount of
+individual variation in birds, and how readily local varieties become
+established wherever the physical conditions are sufficiently distinct. Now
+we can hardly have a greater difference of conditions {252} than between
+the continent of Europe or North Africa, and a group of rocky islands in
+mid-Atlantic, situated in the full course of the Gulf Stream and with an
+excessively mild though stormy climate. We have every reason to believe
+that special modifications would soon become established in any animals
+completely isolated under such conditions. But they are not, as a rule,
+thus completely isolated, because, as we have seen, stragglers arrive at
+short intervals; and these, mixing with the residents, keep up the purity
+of the breed. It follows, that only those species which reach the Azores at
+very remote intervals will be likely to acquire well-marked distinctive
+characters; and this appears to have happened with the bullfinch alone, a
+bird which does not migrate, and is therefore less likely to be blown out
+to sea, more especially as it inhabits woody districts. A few other Azorean
+birds, however, exhibit slight differences from their European allies.
+
+There is another reason for the very slight amount of peculiarity presented
+by the fauna of the Azores as compared with many other oceanic islands,
+dependent on its comparatively recent origin. The islands themselves may be
+of considerable antiquity, since a few small deposits, believed to be of
+Miocene age, have been found on them, but there can be little doubt that
+their present fauna, at all events as concerns the birds, had its origin
+since the date of the last glacial epoch. Even now icebergs reach the
+latitude of the Azores but a little to the west of them; and when we
+consider the proofs of extensive ice-action in North America and Europe, we
+can hardly doubt that these islands were at that time surrounded with
+pack-ice, while their own mountains, reaching 7,600 feet high in Pico,
+would almost certainly have been covered with perpetual snow and have sent
+down glaciers to the sea. They might then have had a climate almost as bad
+as that now endured by the Prince Edward Islands in the southern
+hemisphere, nearly ten degrees farther from the equator, where there are no
+land-birds whatever, although the distance from Africa is not much greater
+than that of the Azores from Europe, while the vegetation is limited to a
+few alpine plants and mosses. This recent origin of the {253} birds
+accounts in a great measure for their identity with those of Europe,
+because, whatever change has occurred must have been effected in the
+islands themselves, and in a time limited to that which has elapsed since
+the glacial epoch passed away.
+
+_Insects of the Azores._--Having thus found no difficulty in accounting for
+the peculiarities presented by the birds of these islands, we have only to
+see how far the same general principles will apply to the insects and
+land-shells. The butterflies, moths, and hymenoptera, are few in number,
+and almost all seem to be common European species, whose presence is
+explained by the same causes as those which have introduced the birds.
+Beetles, however, are more numerous, and have been better studied, and
+these present some features of interest. The total number of species yet
+known is 212, of which 175 are European; but out of these 101 are believed
+to have been introduced by human agency, leaving seventy-four really
+indigenous. Twenty-three of these indigenous species are not found in any
+of the other Atlantic islands, showing that they have been introduced
+directly from Europe by causes which have acted more powerfully here than
+farther south. Besides these there are thirty-six species not found in
+Europe, of which nineteen are natives of Madeira or the Canaries, three are
+American, and fourteen are altogether peculiar to the Azores. These latter
+are mostly allied to species found in Europe or in the other Atlantic
+islands, while one is allied to an American species, and two are so
+distinct as to constitute new genera. The following list of these peculiar
+species will be interesting:--
+
+ CARABIDÆ.
+
+ _Anchomenus aptinoides_ Allied to a species from the Canaries.
+ _Bembidium hesperus_ Allied to the European _B. lætum_.
+
+ DYTISCIDÆ.
+
+ _Agabus godmanni_ Allied to the European _A. dispar_.
+
+ COLYDIIDÆ.
+
+ _Tarphius wollastoni_ A genus almost peculiar to the Atlantic
+ islands.
+ {254}
+
+ ELATERIDÆ.
+
+ _Heteroderes azoricus_ Allied to a Brazilian species.
+ _Elastrus dolosus_ Belongs to a peculiar Madagascar genus!
+
+ MELYRIDÆ.
+
+ _Attalus miniaticollis_ Allied to a Canarian species.
+
+ RHYNCOPHORA.
+
+ _Phlæophagus variabilis_ Allied to European and Atlantic species.
+ _Acalles droueti_ A Mediterranean and Atlantic genus.
+ _Laparocerus azoricus_ Allied to Madeiran species.
+ _Asynonychun godmansi_ A peculiar genus, allied to _Brachyderes_, of
+ the south of Europe.
+ _Neocnemis occidentalis_ A peculiar genus, allied to the European
+ genus _Strophosomus_.
+
+ HETEROMERA.
+
+ _Helops azoricus_ Allied to _H. vulcanus_ of Madeira.
+
+ STAPHYLINIDÆ.
+
+ _Xenomma melanocephala_ Allied to _X. filiforme_ from the Canaries.
+
+This greater amount of speciality in the beetles than in the birds may be
+due to two causes. In the first place many of these small insects have no
+doubt survived the glacial epoch, and may, in that case, represent very
+ancient forms which have become extinct in their native country; and in the
+second place, insects have many more chances of reaching remote islands
+than birds, for not only may they be carried by gales of wind, but
+sometimes, in the egg or larva state or even as perfect insects, they may
+be drifted safely for weeks over the ocean, buried in the light stems of
+plants or in the solid wood of trees in which many of them undergo their
+transformations. Thus we may explain the presence of three common South
+American species (two elaters and a longicorn), all wood-eaters, and
+therefore liable to be occasionally brought in floating timber by the Gulf
+Stream. But insects are also immensely more numerous in species than are
+land-birds, and their transmission would be in most cases quite
+involuntary, and not dependent on their own powers of flight as with birds;
+and thus the chances against the same species being frequently carried to
+the same island would be considerable. If we add to this the dependence of
+so {255} many insects on local conditions of climate and vegetation, and
+their liability to be destroyed by insectivorous birds, we shall see that,
+although there may be a greater probability of insects as a whole reaching
+the islands, the chance against any particular species arriving there, or
+against the same species arriving frequently, is much greater than in the
+case of birds. The result is, that (as compared with Britain for example)
+the birds are, proportionately, much more numerous than the beetles, while
+the peculiar species of beetles are much more numerous than among birds,
+both facts being quite in accordance with what we know of the habits of the
+two groups. We may also remark, that the small size and obscure characters
+of many of the beetles renders it probable that species now supposed to be
+peculiar, really inhabit some parts of Europe or North Africa.
+
+It is interesting to note that the two families which are pre-eminently
+wood, root, or seed eaters, are those which present the greatest amount of
+speciality. The two Elateridæ alone exhibit remote affinities, the one with
+a Brazilian the other with a Madagascar group; while the only peculiar
+genera belong to the Rhyncophora, but are allied to European forms. These
+last almost certainly form a portion of the more ancient fauna of the
+islands which migrated to them in pre-glacial times, while the Brazilian
+elater appears to be the solitary example of a living insect brought by the
+Gulf Stream to these remote shores. The elater, having its nearest living
+ally in Madagascar (_Elastrus dolosus_), cannot be held to indicate any
+independent communication between these distant islands; but is more
+probably a relic of a once more widespread type which has only been able to
+maintain itself in these localities. Mr. Crotch states that there are some
+_species_ of beetles common to Madagascar and the Canary Islands, while
+there are several _genera_, common to Madagascar and South America, and
+some to Madagascar and Australia. The clue to these apparent anomalies is
+found in other genera being common to Madagascar, Africa, and South
+America, while others are Asiatic or Australian. Madagascar, in fact, has
+insect relations with every part of {256} the globe, and the only rational
+explanation of such facts is, that they are indications of very ancient and
+once widespread groups, maintaining themselves only in a few widely
+separated portions of what was at one time or another the area of their
+distribution.
+
+_Land-shells of the Azores._--Like the insects and birds, the land-shells
+of these islands have a generally European aspect, but with a larger
+proportion of peculiar species. This was to be expected, because the means
+by which molluscs are carried over the sea are far less numerous and varied
+than in the case of insects;[51] and we may therefore conclude that their
+introduction is a very rare event, and that a species once arrived remains
+for long periods undisturbed by new arrivals, and is therefore more likely
+to become modified by the new conditions, and then fixed as a distinct
+type. Out of the sixty-nine known species, thirty-seven are common to
+Europe or the other Atlantic islands, while thirty-two are peculiar, though
+almost all are distinctly allied to European types. The majority of these
+shells, especially the peculiar forms, are very small, and many of them may
+date back to beyond the glacial epoch. The eggs of these would be
+exceedingly minute, and might occasionally be carried on leaves or other
+materials during gales of exceptional violence and duration, while others
+might be conveyed with the earth that often sticks to the feet of birds.
+There are also, probably, other unknown means of conveyance; but however
+this may be, the general character of the land-molluscs is such as to
+confirm the conclusions we have arrived at from a study of the birds and
+insects,--that these islands have never been connected with a continent,
+and have been peopled with living things by such forms only as in some way
+or other have been able to reach them across many hundred miles of ocean.
+
+_The Flora of the Azores._--The flowering-plants of the Azores have been
+studied by one of our first botanists, Mr. H. C. Watson, who has himself
+visited the islands and made extensive collections; and he has given a
+complete catalogue of the species in Mr. Godman's volume. As our {257}
+object in the present work is to trace the past history of the more
+important islands by means of the forms of life that inhabit them, and as
+for this purpose plants are sometimes of more value than any class of
+animals, it will be well to take advantage of the valuable materials here
+available, in order to ascertain how far the evidence derived from the two
+organic kingdoms agrees in character; and also to obtain some general
+results which may be of service in our discussion of more difficult and
+more complex problems.
+
+There are in the Azores 480 known species of flowering-plants and ferns, of
+which no less than 440 are found also in Europe, Madeira, or the Canary
+Islands; while forty are peculiar to the Azores, but are more or less
+closely allied to European species. As botanists are no less prone than
+zoologists to invoke former land-connections and continental extensions to
+account for the wide dispersal of objects of their study, it will be well
+to examine somewhat closely what these facts really imply.
+
+_The Dispersal of Seeds._--The seeds of plants are liable to be dispersed
+by a greater variety of agents than any other organisms, while their
+tenacity of life, under varying conditions of heat and cold, drought and
+moisture, is also exceptionally great. They have also an advantage, in that
+the great majority of flowering plants have the sexes united in the same
+individual, so that a single seed in a state fit to germinate may easily
+stock a whole island. The dispersal of seeds has been studied by Sir Joseph
+Hooker, Mr. Darwin, and many other writers, who have made it sufficiently
+clear that they are in many cases liable to be carried enormous distances.
+An immense number are specially adapted to be carried by the wind, through
+the possession of down or hairs, or membranous wings or processes; while
+others are so minute, and produced in such profusion, that it is difficult
+to place a limit to the distance they might be carried by gales of wind or
+hurricanes. Another class of somewhat heavier seeds or dry fruits are
+capable of being exposed for a long time to sea-water without injury. Mr.
+Darwin made many experiments on this point, and he found that many seeds,
+especially of Atriplex, {258} Beta, oats, Capsicum, and the potato, grew
+after 100 days' immersion, while a large number survived fifty days. But he
+also found that most of them sink after a few days' immersion, and this
+would certainly prevent them being floated to very great distances. It is
+very possible, however, that dried branches or flower-heads containing
+seeds would float longer, while it is quite certain that many tropical
+seeds do float for enormous distances, as witness the double cocoa-nuts
+which cross the Indian ocean from the Seychelle Islands to the coast of
+Sumatra, and the West Indian beans which frequently reach the west coast of
+Scotland. There is therefore ample evidence of the possibility of seeds
+being conveyed across the sea for great distances by winds and surface
+currents.[52]
+
+_Birds as Seed-carriers._--The great variety of fruits that are eaten by
+birds afford a means of plant-dispersal in the fact that seeds often pass
+through the bodies of birds in a state well-fitted for germination; and
+such seeds may occasionally be carried long distances by this means. Of the
+twenty-two land-birds found in the Azores, half are, more or less,
+fruit-eaters, and these may have been the means of introducing many plants
+into the islands.
+
+Birds also frequently have small portions of earth on their feet; and Mr.
+Darwin has shown by actual experiment that almost all such earth contains
+seeds. Thus in {259} nine grains of earth on the leg of a woodcock a seed
+of the toad-rush was found which germinated; while a wounded red-legged
+partridge had a ball of earth weighing six and a half ounces adhering to
+its leg, and from this earth Mr. Darwin raised no less than eighty-two
+separate plants of about five distinct species. Still more remarkable was
+the experiment with six and three-quarter ounces of mud from the edge of a
+little pond, which, carefully treated under glass, produced 537 distinct
+plants! This is equal to a seed for every six grains of mud, and when we
+consider how many birds frequent the edges of ponds in search of food, or
+come there to drink, it is evident that great numbers of seeds may be
+dispersed by this means.
+
+Many seeds have hispid awns, hooks, or prickles which readily attach them
+to the feathers of birds, and a great number of aquatic birds nest inland
+on the ground; and as these are pre-eminently wanderers, they must often
+aid in the dispersal of such plants.[53]
+
+{260}
+
+_Facilities for Dispersal of Azorean Plants._--Now in the course of very
+long periods of time the various causes here enumerated would be sufficient
+to stock the remotest islands with vegetation, and a considerable part of
+the Azorean flora appears well adapted to be so conveyed. Of the 439
+flowering-plants in Mr. Watson's list, I find that about forty-five belong
+to genera that have either pappus or winged seeds; sixty-five to such as
+have very minute seeds; thirty have fleshy fruits such as are greedily
+eaten by birds; several have hispid seeds; and eighty-four are glumaceous
+plants, which are all probably well-adapted for being carried partly by
+winds and partly by currents, as well as by some of the other causes
+mentioned. On the other hand we have a very suggestive fact in the absence
+from the Azores of most of the trees and shrubs with large and heavy
+fruits, however common they may be in Europe. Such are oaks, chestnuts,
+hazels, apples, beeches, alders, and firs; while the only trees or large
+shrubs are the Portugal laurel, myrtle, laurestinus, elder, _Laurus
+canariensis_, _Myrica faya_, and a doubtfully peculiar juniper--all small
+berry-bearers, and therefore likely to have been conveyed by one or other
+of the modes suggested above.
+
+There can be little doubt that the truly indigenous flora of the islands is
+far more scanty than the number of plants recorded would imply, because a
+large but unknown proportion of the species are certainly importations,
+voluntary or involuntary, by man. As, however, the general character of the
+whole flora is that of the south-western peninsula of Europe, and as most
+of the introduced plants have come from the same country, it is almost
+impossible now to separate them, and Mr. Watson has not attempted to do so.
+The whole flora contains representatives of eighty natural orders and 250
+genera: and even if we suppose that one-half the species only are truly
+indigenous, {261} there will still remain a wonderfully rich and varied
+flora to have been carried, by the various natural means above indicated,
+over 900 miles of ocean, more especially as the large proportion of species
+identical with those of Europe shows that their introduction has been
+comparatively recent, and that it is, probably (as in the case of the
+birds) still going on. We may therefore feel sure that we have here by no
+means reached the limit of distance to which plants can be conveyed by
+natural means across the ocean; and this conclusion will be of great value
+to us in investigating other cases where the evidence at our command is
+less complete, and the indications of origin more obscure or conflicting.
+
+Of the forty species which are considered to be peculiar to the islands,
+all are allied to European plants except six, whose nearest affinities are
+in the Canaries or Madeira. Two of the Compositæ are considered to be
+distinct genera, but in this order generic divisions rest on slight
+technical distinctions; and the _Campanula vidalii_ is very distinct from
+any other known species. With these exceptions, most of the peculiar
+Azorean species are closely allied to European plants, and are in several
+cases little more than varieties of them. While therefore we may believe
+that the larger part of the existing flora reached the islands since the
+glacial epoch, a portion of it may be more ancient, as there is no doubt
+that a majority of the species could withstand some lowering of
+temperature; while in such a warm latitude and surrounded with sea, there
+would always be many sunny and sheltered spots in which even tender plants
+might flourish.
+
+_Important Deduction from the Peculiarities of the Azorean Fauna and
+Flora._--There is one conclusion to be drawn from the almost wholly
+European character of the Azorean fauna and flora which deserves special
+attention, namely, that the peopling of remote islands is not due so much
+to ordinary or normal, as to extraordinary and exceptional causes. These
+islands lie in the course of the south-westerly return trades and also of
+the Gulf Stream, and we should therefore naturally expect that American
+birds, insects, and plants would preponderate if they were {262} conveyed
+by the regular winds and currents, which are both such as to prevent
+European species from reaching the islands. But the violent storms to which
+the Azores are liable blow from all points of the compass; and it is
+evidently to these, combined with the greater proximity and more favourable
+situation of the coasts of Europe and North Africa, that the presence of a
+fauna and flora so decidedly European is to be traced.
+
+
+
+The other North Atlantic Islands--Madeira, the Canaries, and the Cape de
+Verdes--present analogous phenomena to those of the Azores, but with some
+peculiarities dependent on their more southern position, their richer
+vegetation, and perhaps their greater antiquity. These have been
+sufficiently discussed in my _Geographical Distribution of Animals_ (Vol.
+I. pp. 208-215); and as we are now dealing with what may be termed typical
+examples of oceanic islands, for the purpose of illustrating the laws, and
+solving the problems presented by the dispersal of animals, we will pass on
+to other cases which have been less fully discussed in that work.
+
+BERMUDA.
+
+The Bermudas are a small group of low islands formed of coral, and blown
+coral-sand consolidated into rock. They are situated in 32° N. Lat., about
+700 miles from North Carolina, and somewhat farther from the Bahama
+Islands, and are thus rather more favourably placed for receiving
+immigrants from America and its islands than the Azores are with respect to
+Europe. There are about 100 islands and islets in all, but their total area
+does not exceed fifty square miles. They are surrounded by reefs, some at a
+distance of thirty miles from the main group; and the discovery of a layer
+of earth with remains of cedar-trees forty-eight feet below the present
+high-water mark shows that the islands have once been more extensive and
+probably included the whole area now occupied by shoals and reefs.[54]
+Immediately beyond these reefs, {263} however, extends a very deep ocean,
+while about 450 miles distant in a south-east direction, the deepest part
+of the North Atlantic is reached, where soundings of 3,825 and 3,875
+fathoms have been obtained. It is clear therefore that these islands are
+typically oceanic.
+
+[Illustration: MAP OF BERMUDA AND THE AMERICAN COAST.]
+
+ NOTE.--The light tint indicates sea less than 1,000 fathoms deep.
+ The dark tint ,, ,, more than 1,000 fathoms deep.
+ The figures show the depth in fathoms.
+
+Soundings were taken by the _Challenger_ in four {264} different directions
+around Bermuda, and always showed a rapid deepening of the sea to about
+2,500 fathoms. This was so remarkable, that in his reports to the
+Admiralty, Captain Nares spoke of Bermuda as "a solitary peak rising
+abruptly from a base only 120 miles in diameter;" and in another place as
+"an isolated peak rising abruptly from a very small base." These
+expressions show that Bermuda is looked upon as a typical example of an
+"oceanic peak"; and on examining the series of official reports of the
+_Challenger_ soundings, I can find no similar case, although some coasts,
+both of continents and islands, descend more abruptly. In order to show,
+therefore, what is the real character of this peak, I have drawn a section
+of it on a true scale from the soundings taken in a north and south
+direction where the descent is steepest. It will be seen that the slope is
+on both sides very easy, being 1 in 16 on the south, and 1 in 19 on the
+north. The portion nearest the islands will slope more rapidly, perhaps
+reaching in places 1 in 10; but even this is not steeper than many country
+roads in hilly countries, while the remainder would be a hardly perceptible
+slope. Although generally very low, some parts of these islands rise to 250
+feet above the sea-level, consisting of various kinds of limestone rock,
+sometimes soft and friable, but often very hard and even crystalline. It
+consists of beds which sometimes dip as much as 30°, and which also show
+great contortions, so that at first sight the islands appear to exhibit on
+a small scale the phenomena of a disturbed Palæozoic district. It has
+however long been known that these rocks are all due to the wind, {265}
+which blows up the fine calcareous sand, the product of the disintegration
+of coral, shells, serpulæ, and other organisms, forming sand-hills forty
+and fifty feet high, which move gradually along, overwhelming the lower
+tracts of land behind them. These are consolidated by the percolation of
+rain-water, which dissolves some of the lime from the more porous tracts
+and deposits it lower down, filling every fissure with stalagmite.
+
+[Illustration: SECTION OF BERMUDA AND ADJACENT SEA BOTTOM.
+
+The figures show the depth in fathoms at fifty-five miles north and
+forty-six miles south of the islands respectively.]
+
+_The Red Clay of Bermuda._--Besides the calcareous rocks there is found in
+many parts of the islands a layer of red earth or clay, containing about
+thirty per cent. of oxide of iron. This very closely resembles, both in
+colour and chemical composition, the red clay of the ocean floor, found
+widely spread in the Atlantic at depths of from 2,300 to 3,150 fathoms, and
+occurring abundantly all round Bermuda. It appears, therefore, at first
+sight, as if the ocean bed itself has been here raised to the surface, and
+a portion of its covering of red clay preserved; and this is the view
+adopted by Mr. Jones in his paper on the "Botany of Bermuda." He says,
+after giving the analysis: "This analysis tends to convince us that the
+deep chocolate-coloured red clay of the islands found in the lower levels,
+and from high-water mark some distance into the sea, originally came from
+the ocean floor, and that when by volcanic agency the Bermuda column was
+raised from the depths of the sea, its summit, most probably broken in
+outline, appeared above the surface covered with this red mud, which in the
+course of ages has but slightly changed its composition, and yet possesses
+sufficient evidence to prove its identity with that now lying contiguous to
+the base of the Bermuda column." But in his _Guide to Bermuda_ Mr. Jones
+tells us that this same red earth has been found, two feet thick, under
+coral rock at a depth of forty-two feet below low-water mark, and that it
+"rested on a bed of compact calcareous sandstone." Now it is quite certain
+that this "calcareous sandstone" was never formed at the bottom of the deep
+ocean 700 miles from land; and the occurrence of the red earth at different
+levels upon coralline sand rock is therefore more probably due to some
+process of decomposition of the rock itself, {266} or of the minute
+organisms which abound in the blown sand.[55]
+
+_Zoology of Bermuda._--As might be expected from their extreme isolation,
+these islands possess no indigenous terrestrial mammalia, frogs, or
+snakes.[56] There is however one lizard, which Professor Cope considers to
+be distinct from any American species, and which he has named _Plestiodon
+(Eumeces) longirostris_. It is said to be most nearly allied to _Eumeces
+quinquelineatus_ of the south-eastern States, from which it differs in
+having nearly ten more rows of scales, the tail thicker, and the muzzle
+longer. In colour it is ashy brown above, greenish blue beneath, with a
+white line black-margined on the sides, and it seems to be tolerably
+abundant in the islands. This lizard is especially interesting as being the
+only vertebrate animal which exhibits any peculiarity.
+
+_Birds._--Notwithstanding its small size, low altitude and {267} remote
+position, a great number of birds visit Bermuda annually, some in large
+numbers, others only as accidental stragglers. Altogether, over 180 species
+have been recorded, rather more than half being wading and swimming birds,
+whose presence is not so much to be wondered at as they are great
+wanderers; while about eighty-five are land birds, many of which would
+hardly be supposed capable of flying so great a distance. Of the 180
+species, however, about thirty have only been seen once, and a great many
+more are very rare; but about twenty species of land birds are recorded as
+tolerably frequent visitors, and nearly half these appear to come every
+year.
+
+There are only eleven species which are permanent residents on the
+island--eight land, and three water birds, and of these one has been almost
+certainly introduced. These resident birds are as follows:--
+
+ 1. _Galeoscoptes carolinensis._ (The Cat bird.) Migrates along the east
+ coast of the United States.
+
+ 2. _Sialia sialis._ (The Blue bird.) Migrates along the east coast.
+
+ 3. _Vireo novæboracensis._ (The White-eyed green Tit.) Migrates along
+ the east coast.
+
+ 4. _Passer domesticus._ (The English Sparrow.) ? Introduced.
+
+ 5. _Corvus americanus._ (The American Crow.) Common over all North
+ America.
+
+ 6. _Cardinalis virginianus._ (The Cardinal bird.) Migrates from
+ Carolina southward.
+
+ 7. _Chamoepelia passerina._ (The ground Dove.) Louisiana, W. Indies,
+ and Mexico.
+
+ 8. _Ortyx virginianus._ (The American Quail.) New England to Florida.
+
+ 9. _Ardea herodias._ (The Great Blue Heron.) All North America.
+
+ 10. _Gailinula galeata._ (The Florida Gallinule.) Temperate and
+ tropical North America.
+
+ 11. _Phäeton flavirostris._ (The Tropic Bird.)
+
+It will be seen that these are all very common North American birds, and
+most of them are constant visitors from the mainland, so that however long
+they may have inhabited the islands there has been no chance for them to
+have acquired any distinctive characters owing to the want of isolation.
+
+Among the most regular visitants which are not resident, are the common N.
+American kingfisher (_Ceryle alcyon_), {268} the night-hawk (_Chordeiles
+virginianus_), the wood wagtail (_Siurus novæboracensis_), the snow-bunting
+(_Plectrophanes nivalis_), and the wide-ranging rice-bird (_Dolichonyx
+oryzivora_), all very common and widespread in North America.
+
+_Comparison of the Bird-faunas of Bermuda and the Azores._--The bird-fauna
+of Bermuda thus differs from that of the Azores, in the much smaller number
+of resident species, and the presence of several regular migrants. This is
+due, first, to the small area and little varied surface of these islands,
+as well as to their limited flora and small supply of insects not affording
+conditions suitable for the residence of many species all the year round;
+and, secondly, to the peculiarity of the climate of North America, which
+causes a much larger number of its birds to be migratory than in Europe.
+The Northern United States and Canada, with a sunny climate, luxuriant
+vegetation, and abundant insect-life during the summer, supply food and
+shelter to an immense number of insectivorous and frugivorous birds; so
+that during the breeding season Canada is actually richer in bird-life than
+Florida. But as the severe winter comes on all these are obliged to migrate
+southward, some to Carolina, Georgia, and Florida, others as far as the
+West Indies, Mexico, or even to Guatemala and South America.
+
+Every spring and autumn, therefore a vast multitude of birds, belonging to
+more than a hundred distinct species, migrate northward or southward in
+Eastern America. A large proportion of these pass along the Atlantic coast,
+and it has been observed that many of them fly some distance out to sea,
+passing straight across bays from headland to headland by the shortest
+route.
+
+Now as the time of these migrations is the season of storms, especially the
+autumnal one, which nearly coincides with the hurricanes of the West Indies
+and the northerly gales of the coast of America, the migrating birds are
+very liable to be carried out to sea. Sometimes they may, as Mr. Jones
+suggests, be carried up by local whirlwinds to a great height, where
+meeting with a westerly or north-westerly gale, they are rapidly driven
+sea-ward. The great majority no doubt perish, but some reach the Bermudas
+{269} and form one of its most striking autumnal features. In October, Mr.
+Jones tells us, the sportsman enjoys more shooting than at any other time.
+The violent revolving gales, which occur almost weekly, bring numbers of
+birds of many species from the American continent, the different members of
+the duck tribe forming no inconsiderable portion of the whole; while the
+Canada goose, and even the ponderous American swan, have been seen amidst
+the migratory host. With these come also such delicate birds as the
+American robin (_Turdus migratorius_), the yellow-rumped warbler
+(_Dendroeca coronata_), the pine warbler (_Dendroeca pinus_), the wood
+wagtail (_Siurus novæboracensis_), the summer red bird (_Pyranga æstiva_),
+the snow-bunting (_Plectrophanes nivalis_), the red-poll (_Ægiothus
+linarius_), the king bird (_Tyrannus carolinensis_), and many others. It is
+no doubt in consequence of this repeated immigration that none of the
+Bermuda birds have acquired any special peculiarity constituting even a
+distinct variety; for the few species that are resident and breed in the
+islands are continually crossed by individual immigrants of the same
+species from the mainland.
+
+Four European birds also have occurred in Bermuda;--the wheatear (_Saxicola
+oenanthe_), which visits Iceland and Lapland and sometimes the northern
+United States; the skylark (_Alauda arvensis_), but this was probably an
+imported bird or an escape from some ship; the land-rail (_Crex
+pratensis_), which also wanders to Greenland and the United States; and the
+common snipe (_Scolopax gallinago_), which occurs not unfrequently in
+Greenland but has not yet been noticed in North America. It is however so
+like the American snipe (_S. wilsoni_), that a straggler might easily be
+overlooked.
+
+Two small bats of N. American species also occasionally reach the island,
+while two others from the West Indies have more rarely occurred, and these
+are the only wild mammalia except rats and mice.
+
+_Insects of Bermuda._--Insects appear to be very scarce; but it is evident
+from the lists given by Mr. Jones, and more recently by Professor Heilprin,
+that only the more conspicuous species have been yet collected. These {270}
+comprise nineteen beetles, eleven bees and wasps, twenty-six butterflies
+and moths, nine flies, and the same number of Hemiptera, Orthoptera, and
+Neuroptera respectively. All appear to be common North American or West
+Indian species; but until some competent entomological collector visits the
+islands it is impossible to say whether there are or are not any peculiar
+species.[57]
+
+_Land Mollusca._--The land-shells of the Bermudas are somewhat more
+interesting, as they appear to be the only group of animals except reptiles
+in which there are any peculiar species. The following list was kindly
+furnished me by Mr. Thomas Bland of New York, who has made a special study
+of the terrestrial molluscs of the West Indian Islands, from which those of
+the Bermudas have undoubtedly been derived. The nomenclature has been
+corrected in accordance with the list given in Professor Heilprin's work on
+the islands. The species which are peculiar to the islands are indicated by
+italics.
+
+LIST OF THE LAND-SHELLS OF BERMUDA.
+
+ 1. Succinea fulgens. (Lea.) Also in Cuba.
+
+ 2. ,, Bermudensis. (Pfeiffer.) ,, Barbadoes (?)
+
+ 3. ,, margarita. (Pfr.) ,, Haiti.
+
+ 4. _Poecilozonites Bermudensis._ (Pfr.) A peculiar form, which, according
+ to Mr. Binney, "cannot be
+ placed in any recognised genus."
+ A larger sub-fossil variety also
+ occurs, named _H. Nelsoni_, by
+ Mr. Bland, and which appears
+ sufficiently distinct to be
+ classed as another species.
+
+ 5. ,, _circumfirmatas_ (Redfield.)
+
+ 6. ,, _discrepans._ (Pfr.)
+
+ 7. ,, _Reinianus._ (Pfr.)
+
+ 8. Patula (Thysanophora) hypolepta (Shuttleworth.)
+
+ 9. ,, vortex. (Pfr.) Southern Florida and West Indies.
+
+ 10. Helix microdonta. (Desh.) Bahama Islands, Florida, Texas.
+
+ 11. ,, appressa. (Say.) Virginia and adjacent states;
+ perhaps introduced into Bermuda.
+
+ {271}
+ 12. ,, pulchella. (Müll.) Europe; very close to _H.
+ minuta_ (Say) of the United
+ States. Introduced into Bermuda
+ (?)
+
+ 13. ,, ventricosa. (Drap.) Azores, Canary Islands, and South
+ Europe.
+
+ 14. Bulimulus nitidulus. (Pfr.) Cuba, Haiti, &c.
+
+ 15. Stenogyra octona. (Ch.) West Indies and South America.
+
+ 16. Stenogyra decollata (Linn.) A South European species.
+ Introduced.
+
+ 17. Coecilianella acicula. (Müll.) Florida, New Jersey, and Europe.
+
+ 18. Pupa pellucida. (Pfr.) West Indies, and Yucatan.
+
+ 19. ,, Barbadensis. (Pfr.) Barbadoes (?)
+
+ 20. ,, Jamaicensis. (C. B. Ad.) Jamaica.
+
+ 21. Helicina convexa. (Pfr.) Barbuda.[58]
+
+Mr. Bland indicates only four species as certainly peculiar to Bermuda, and
+another sub-fossil species; while one or two of the remainder are indicated
+as doubtfully identical with those of other countries. We have thus about
+one-fifth of the land-shells peculiar, while almost all the other
+productions of the islands are identical with those of the adjacent
+continent and islands. This corresponds, however, with what occurs
+generally in islands at some distance from continents. In the Azores only
+one land-bird is peculiar out of eighteen resident species; the beetles
+show about one-eighth of the probably non-introduced species as peculiar;
+the plants about one-twentieth; while the land-shells have about half the
+species peculiar. This difference is well explained by the much greater
+difficulty of transmission over wide seas, in the case of land-shells, than
+of any other terrestrial organisms. It thus happens that when a species has
+once been conveyed it may remain isolated for unknown ages, and has time to
+become modified by local conditions unchecked by the introduction of other
+individuals of the original type.
+
+_Flora of Bermuda._--Unfortunately no good account of the plants of these
+islands has yet been published. Mr. {272} Jones, in his paper "On the
+Vegetation of the Bermudas" gives a list of no less than 480 species of
+flowering plants; but this number includes all the culinary plants,
+fruit-trees, and garden flowers, as well as all the ornamental trees and
+shrubs from various parts of the world which have been introduced, mixed up
+with the European and American weeds that have come with agricultural or
+garden seeds, and the really indigenous plants, in one undistinguished
+series. It appears too, that the late Governor, Major-General Lefroy, "has
+sown and distributed throughout the islands packets of seeds from Kew,
+representing no less than 600 species, principally of trees and shrubs
+suited to sandy coast soils"--so that it will be more than ever difficult
+in future years to distinguish the indigenous from the introduced
+vegetation.
+
+From the researches of Dr. Rein and Mr. Moseley there appear to be about
+250 flowering plants in a wild state, and of these Mr. Moseley thinks less
+than half are indigenous. The majority are tropical and West Indian, while
+others are common to the Southern States of North America; the former class
+having been largely brought by means of the Gulf Stream, the latter by the
+agency of birds or by winds. Mr. Jones tells us that the currents bring
+numberless objects animate and inanimate from the Carribean Sea, including
+the seeds of trees, shrubs, and other plants, which are continually cast
+ashore and sometimes vegetate. The soap-berry tree (_Sapindus saponaria_)
+has been actually observed to originate in this way.
+
+The only _species_ of flowering plant peculiar to Bermuda is _Carex
+Bermudiana_ (Hemsley), which is said to be allied to a species found only
+in St. Helena; but there are some local forms of continental species, among
+which are _Sisyrinchium Bermudianum_ and a variety of _Rhus toxicodendron_.
+There are, however, two ferns--an Adiantum and a Nephrodium, which are
+unknown from any other locality. The juniper, which is so conspicuous a
+feature of the islands, is said to be a West Indian species (_Juniperus
+barbadensis_) found in Jamaica and the Bahamas, not the North American red
+{273} cedar; but there seems to be still some doubt about this common
+plant.
+
+Mr. Moseley, who visited Bermuda in the _Challenger_, has well explained
+the probable origin of the vegetation. The large number of West Indian
+plants is no doubt due to the Gulf Stream and constant surface drift of
+warm water in this direction, while others have been brought by the annual
+cyclones which sweep over the intervening ocean. The great number of
+American migratory birds, including large flocks of the American golden
+plover, with ducks and other aquatic species, no doubt occasionally bring
+seeds, either in the mud attached to their feet or in their stomachs.[59]
+As these causes are either constantly in action or recur annually, it is
+not surprising that almost all the species should be unchanged owing to the
+frequent intercrossing of freshly-arrived specimens. If a competent
+botanist were thoroughly to explore Bermuda, eliminate the species
+introduced by human agency, and investigate the source from whence the
+others were derived and the mode by which they had reached so remote an
+island, we should obtain important information as to the dispersal of
+plants, which might afford us a clue to the solution of many difficult
+problems in their geographical distribution.
+
+_Concluding Remarks._--The two groups of islands we have now been
+considering furnish us with some most instructive facts as to the power of
+many groups of organisms to pass over from 700 to 900 miles of open sea.
+There is no doubt whatever that all the indigenous species have thus
+reached these islands, and in many cases the process may be seen going on
+from year to year. We find that, as regards birds, migratory habits and the
+liability to be caught by violent storms are the conditions which determine
+the island-population. In both islands the land-birds are almost
+exclusively migrants; and in both, the non-migratory groups--wrens, tits,
+creepers, and nuthatches--are absent; while the number of annual visitors
+is greater in proportion as the migratory habits and prevalence of storms
+afford more efficient means for their introduction. {274}
+
+We find also, that these great distances do not prevent the immigration of
+some insects of most of the orders, and especially of a considerable number
+and variety of beetles; while even land-shells are fairly represented in
+both islands, the large proportion of peculiar species clearly indicating
+that, as we might expect, individuals of this group of organisms arrive
+only at long and irregular intervals.
+
+Plants are represented by a considerable variety of orders and genera, most
+of which show some special adaptation for dispersal by wind or water, or
+through the medium of birds; and there is no reason to doubt that besides
+the species that have actually established themselves, many others must
+have reached the islands, but were either not suited to the climate and
+other physical conditions, or did not find the insects necessary to their
+fertilisation, and were therefore unable to maintain themselves.
+
+If now we consider the extreme remoteness and isolation of these islands,
+their small area and comparatively recent origin, and that, notwithstanding
+all these disadvantages, they have acquired a very considerable and varied
+flora and fauna, we shall, I think, be convinced, that with a larger area
+and greater antiquity, mere separation from a continent by many hundred
+miles of sea would not prevent a country from acquiring a very luxuriant
+and varied flora, and a fauna also rich and peculiar as regards all classes
+except terrestrial mammals, amphibia, and some groups of reptiles. This
+conclusion will be of great importance in those cases where the evidence as
+to the exact origin of the fauna and flora of an island is less clear and
+satisfactory than in the case of the Azores and Bermuda.
+
+ * * * * *
+
+
+{275}
+
+CHAPTER XIII
+
+THE GALAPAGOS ISLANDS
+
+ Position and Physical Features--Absence of Indigenous Mammalia and
+ Amphibia--Reptiles--Birds--Insects and Land-Shells--The Keeling Islands
+ as Illustrating the Manner in which Oceanic Islands are Peopled--Flora
+ of the Galapagos--Origin of the Flora of the Galapagos--Concluding
+ Remarks.
+
+The Galapagos differ in many important respects from the islands we have
+examined in our last chapter, and the differences are such as to have
+affected the whole character of their animal inhabitants. Like the Azores,
+they are volcanic, but they are much more extensive, the islands being both
+larger and more numerous; while volcanic action has been so recent that a
+large portion of their surface consists of barren lava-fields. They are
+considerably less distant from a continent than either the Azores or
+Bermuda, being about 600 miles from the west coast of South America and a
+little more than 700 from Veragua, with the small Cocos Islands
+intervening; and they are situated on the equator instead of being in the
+north temperate zone. They stand upon a deeply submerged bank, the 1,000
+fathom line encircling all the more important islands at a few miles
+distance, whence there appears to be a comparatively steep descent all
+round to the average depth of that portion of the Pacific, between 2,000
+and 3,000 fathoms. {276}
+
+[Illustration: MAP OF THE GALAPAGOS AND ADJACENT COASTS OF SOUTH AMERICA.]
+
+ The light tint shows where the sea is less than 1,000 fathoms deep.
+ The figures show the depth in fathoms.
+
+The whole group occupies a space of about 300 by 200 miles. It consists of
+five large and twelve small islands; the largest (Albemarle Island) being
+about eighty miles long and of very irregular shape, while the four next in
+importance--Chatham, Indefatigable, James, and Narborough Islands, are each
+about twenty-five or thirty miles {277} long, and of a rounded or elongate
+form. The whole are entirely volcanic, and in the western islands there are
+numerous active volcanoes. Unlike the other groups of islands we have been
+considering, these are situated in a comparatively calm sea, where storms
+are of rare occurrence and even strong winds almost unknown. They are
+traversed by ocean currents which are strong and constant, flowing towards
+the north-west from the coast of Peru; {278} and these physical conditions
+have had a powerful influence on the animal and vegetable forms by which
+the islands are now inhabited. The Galapagos have also, during three
+centuries, been frequently visited by Europeans, and were long a favourite
+resort of buccaneers and traders, who found an ample supply of food in the
+large tortoises which abound there; and to these visits we may perhaps
+trace the introduction of some animals whose presence it is otherwise
+difficult to account for. The vegetation is generally scanty, but still
+amply sufficient for the support of a considerable amount of animal life,
+as shown by the cattle, horses, asses, goats, pigs, dogs, and cats, which
+now run wild in some of the islands.
+
+[Illustration: MAP OF THE GALAPAGOS.]
+
+ The light tint shows a depth of less than 1,000 fathoms.
+ The figures show the depth in fathoms.
+
+_Absence of Indigenous Mammalia and Amphibia._--As in all other oceanic
+islands, we find here no truly indigenous mammalia, for though there is a
+mouse of the American genus Hesperomys, which differs somewhat from any
+known species, we can hardly consider this to be indigenous; first, because
+these creatures have been little studied in South America, and there may
+yet be many undescribed species, and in the second place because even had
+it been introduced by some European or native vessel, there is ample time
+in two or three hundred years for the very different conditions to have
+established a marked diversity in the characters of the species. This is
+the more probable because there is also a true rat of the Old World genus
+Mus, which is said to differ slightly from any known species; and as this
+genus is not a native of the American continents we are sure that it must
+have been recently introduced into the Galapagos. There can be little doubt
+therefore that the islands are completely destitute of truly indigenous
+mammalia; and frogs and toads, the only tropical representatives of the
+Amphibia, are equally unknown.
+
+_Reptiles._--Reptiles, however, which at first sight appear as unsuited as
+mammals to pass over a wide expanse of ocean, abound in the Galapagos,
+though the species are not very numerous. They consist of land-tortoises,
+lizards and snakes. The tortoises consist of two peculiar species, _Testudo
+microphyes_, found in most of the islands, and _T. {279} abingdonii_
+recently discovered on Abingdon Island, as well as one extinct species, _T.
+ephippium_, found on Indefatigable Island. These are all of very large
+size, like the gigantic tortoises of the Mascarene Islands, from which,
+however, they differ in structural characters; and Dr. Günther believes
+that they have been originally derived from the American continent.[60]
+Considering the well known tenacity of life of these animals, and the large
+number of allied forms which have aquatic or sub-aquatic habits, it is not
+a very extravagant supposition that some ancestral form, carried out to sea
+by a flood, was once or twice safely drifted as far as the Galapagos, and
+thus originated the races which now inhabit them.
+
+The lizards are five in number; a peculiar species of gecko,
+_Phyllodactylus galapagensis_, and four species of the American family
+Iguanidæ. Two of these are distinct species of the genus Tropidurus, the
+other two being large, and so very distinct as to be classed in peculiar
+genera. One of these is aquatic and found in all the islands, swimming in
+the sea at some distance from the shore and feeding on seaweed; the other
+is terrestrial, and is confined to the four central islands. These last
+were originally described as _Amblyrhynchus cristatus_ by Mr. Bell, and _A.
+subcristatus_ by Gray; they were afterwards placed in two other genera
+Trachycephalus and Oreocephalus (_see_ Brit. Mus. Catalogue of Lizards),
+while in a recent paper by Dr. Steindachner, the marine species is again
+classed as Amblyrhynchus, while the terrestrial form is placed in another
+genus Conolophus, both genera being peculiar to the Galapagos.
+
+How these lizards reached the islands we cannot tell. The fact that they
+all belong to American genera or families indicates their derivation from
+that continent, while their being all distinct species is a proof that
+their arrival took place at a remote epoch, under conditions perhaps
+somewhat different from any which now prevail. It is certain that animals
+of this order have some means of crossing the sea not possessed by any
+other land vertebrates, {280} since they are found in a considerable number
+of islands which possess no mammals nor any other land reptiles; but what
+those means are has not yet been positively ascertained.
+
+It is unusual for oceanic islands to possess snakes, and it is therefore
+somewhat of an anomaly that two species are found in the Galapagos. Both
+are closely allied to South American forms, and one is hardly different
+from a Chilian snake, so that they indicate a more recent origin than in
+the case of the lizards. Snakes it is known can survive a long time at sea,
+since a living boa-constrictor once reached the island of St. Vincent from
+the coast of South America, a distance of two hundred miles by the shortest
+route. Snakes often frequent trees, and might thus be conveyed long
+distances if carried out to sea on a tree uprooted by a flood such as often
+occurs in tropical climates and especially during earthquakes. To some such
+accident we may perhaps attribute the presence of these creatures in the
+Galapagos, and that it is a very rare one is indicated by the fact that
+only two species have as yet succeeded in obtaining a footing there.
+
+_Birds._--We now come to the birds, whose presence here may not seem so
+remarkable, but which yet present features of interest not exceeded by any
+other group. About seventy species of birds have now been obtained on these
+islands, and of these forty-one are peculiar to them. But all the species
+found elsewhere, except one, belong to the aquatic tribes or the waders
+which are pre-eminently wanderers, yet even of these eight are peculiar.
+The true land-birds are forty-two in number, and all but one are entirely
+confined to the Galapagos; while three-fourths of them present such
+peculiarities that they are classed in distinct genera. All are allied to
+birds inhabiting tropical America, some very closely; while one--the common
+American rice-bird which ranges over the whole northern and part of the
+southern continents--is the only land-bird identical with those of the
+mainland. The following is a list of these land-birds taken from Mr.
+Salvin's memoir in the _Transactions of the Zoological Society_ for the
+year 1876, to which are added nine species collected in 1888 and {281}
+described by Mr. Ridgway in the _Proceedings of the U.S. National Museum_
+(XII. p. 101) and some additional species obtained in 1889.
+
+ TURDIDÆ.
+
+ 1. Nesomimus trifasciatus } This and the two allied species
+ 2. ,, melanotus } are related to a Peruvian bird
+ 3. ,, parvulus } _Mimus longicaudus_.
+ 4. ,, macdonaldi (Ridg.)
+ 5. ,, personatus (Ridg.)
+
+ MNIOTILTIDÆ.
+
+ 6. Dendroeca aureola { Closely allied to the wide-ranging
+ { _D. æstiva_.
+
+ HIRUNDINIDÆ.
+
+ 7. Progne concolor { Allied to _P. purpurea_ of North
+ { and South America.
+
+ COEREBIDÆ.
+
+ 8. Certhidea olivacea } A peculiar genus allied to the
+ 9. ,, fusca } Andean genus Conirostrum.
+ 10. ,, cinerascens }
+
+ FRINGILLIDÆ.
+
+ 11. Geospiza magnirostris
+ 12. ,, strenua
+ 13. ,, dubia A distinct genus, but allied to the
+ 14. ,, fortis South American genus Guiraca.
+ 15. ,, nebulosa
+ 16. ,, fuliginosa
+ 17. ,, parvula
+ 18. ,, dentirostris
+ 19. ,, conirostris (Ridg.)
+ 20. ,, media (Ridg.)
+ 21. ,, difficilis (Sharpe)
+ 22. Cactornis scandens
+ 23. ,, assimilis
+ 24. ,, abingdoni
+ 25. ,, pallida A genus allied to the last.
+ 26. ,, brevirostris (Ridg.)
+ 27. ,, hypoleuca (Ridg.) A very peculiar genus allied to
+ 28. Camarhynchus psittaculus Neorhynchus of the west coast
+ 29. ,, crassirostris of Peru.
+ 30. ,, variegatus
+ 31. ,, prosthemelas
+ 32. ,, habeli
+ 33. ,, townsendi (Ridg.)
+ 34. ,, pauper (Ridg.)
+ {282}
+
+ ICTERIDÆ.
+
+ 35. Dolichonyx oryzivorus Ranges from Canada to Paraguay.
+
+ TYRANNIDÆ.
+
+ 36. Pyrocephalus nanus
+ 37. P. minimus (Ridg.) Allied to _P. rubincus_ of Ecuador.
+ 38. Myiarchus magnirostris Allied to West Indian species.
+
+ COLUMBIDÆ.
+
+ 39. Zenaida galapagensis { A peculiar species of a S.
+ { American genus.
+
+ FALCONIDÆ.
+
+ 40. Buteo galapagensis A buzzard of peculiar coloration.
+
+ STRIGIDÆ.
+
+ 41. Asio galapagensis } Hardly distinct from the widespread
+ } _A. brachyotus._
+
+ 42. Strix punctatissima Allied to _S. flammea_ but quite
+ distinct.
+
+We have here every gradation of difference from perfect identity with the
+continental species to genera so distinct that it is difficult to determine
+with what forms they are most nearly allied; and it is interesting to note
+that this diversity bears a distinct relation to the probabilities of, and
+facilities for, migration to the islands. The excessively abundant
+rice-bird, which breeds in Canada and swarms over the whole United States,
+migrating to the West Indies and South America, visiting the distant
+Bermudas almost every year, and extending its range as far as Paraguay, is
+the only species of land-bird which remains completely unchanged in the
+Galapagos; and we may therefore conclude that some stragglers of the
+migrating host reach the islands sufficiently often to keep up the purity
+of the breed. Next, we have the almost cosmopolite short-eared owl (_Asio
+brachyotus_), which ranges from China to Ireland, and from Greenland to the
+Straits of Magellan, and of this the Galapagos bird is probably only one of
+the numerous varieties. The little wood warbler (_Dendroeca aureola_) is
+closely allied to a species which {283} ranges over the whole of North
+America and as far south as New Grenada. It has also been occasionally met
+with in Bermuda, an indication that it has considerable powers of flight
+and endurance. The more distinct _species_--as the tyrant fly-catchers
+(Pyrocephalus and Myiarchus), the ground-dove (Zenaida), and the buzzard
+(Buteo), are all allied to non-migratory species peculiar to tropical
+America, and of a more restricted range; while the distinct _genera_ are
+allied to South American groups of thrushes, finches, and sugar-birds which
+have usually restricted ranges, and whose habits are such as not to render
+them likely to be carried out to sea. The remote ancestral forms of these
+birds which, owing to some exceptional causes, reached the Galapagos, have
+thus remained uninfluenced by later migrations, and have, in consequence,
+been developed into a variety of distinct types adapted to the peculiar
+conditions of existence under which they have been placed. Sometimes the
+different species thus formed are confined to one or two of the islands
+only, as the three species of Certhidea, which are divided between the
+islands but do not appear ever to occur together. _Nesomimus parvulus_ is
+confined to Albemarle Island, and _N. trifasciatus_ to Charles Island;
+_Cactornis pallida_ to Indefatigable Island, _C. brevirostris_ to Chatham
+Island, and _C. abingdoni_ to Abingdon Island.
+
+Now all these phenomena are strictly consistent with the theory of the
+peopling of the islands by accidental migrations, if we only allow them to
+have existed for a sufficiently long period; and the fact that volcanic
+action has ceased on many of the islands, as well as their great extent,
+would certainly indicate a considerable antiquity.
+
+The great difference presented by the birds of these islands as compared
+with those of the equally remote Azores and Bermudas, is sufficiently
+explained by the difference of climatal conditions. At the Galapagos there
+are none of those periodic storms, gales, and hurricanes which prevail in
+the North Atlantic, and which every year carry some straggling birds of
+Europe or North America to the former islands; while, at the same time, the
+majority of the tropical American birds are {284} nonmigratory, and thus
+afford none of the opportunities presented by the countless hosts of
+migrants which pass annually northward and southward along the European,
+and especially along the North American coasts. It is strictly in
+accordance with these different conditions that we find in one case an
+almost perfect identity with, and in the other an almost equally complete
+diversity from, the continental species of birds.
+
+_Insects and Land-shells._--The other groups of land-animals add little of
+importance to the facts already referred to. The insects are very scanty;
+the most plentiful group, the beetles, only furnishing about forty species
+belonging to thirty-two genera and nineteen families. The species are
+almost all peculiar, as are some of the genera. They are mostly small and
+obscure insects, allied either to American or to world-wide groups. The
+Carabidæ and the Heteromera are the most abundant groups, the former
+furnishing six and the latter nine species.[61]
+
+{285}
+
+The land-shells are not abundant--about twenty in all, most of them
+peculiar species, but not otherwise remarkable. The observation of Captain
+Collnet, quoted by Mr. Darwin in his _Journal_, that drift-wood, bamboos,
+canes, and the nuts of a palm, are often washed on the south-eastern shores
+of the islands, furnishes an excellent clue to the manner in which many of
+the insects and land-shells may have reached the Galapagos. Whirlwinds also
+have been known to carry quantities of leaves and other vegetable _débris_
+to great heights in the air, and these might be then carried away by strong
+upper currents and dropped at great distances, and with them small insects
+and mollusca, or their eggs. We must also remember that volcanic islands
+are subject to subsidence as well as elevation; and it is quite possible
+that during the long period the Galapagos have existed some islands may
+have intervened between them and the coast, and have served as
+stepping-stones by which the passage to them of various organisms would be
+greatly facilitated. Sunken banks, the relics of such islands, are known to
+exist in many parts of the ocean, and countless others, no doubt, remain
+undiscovered.
+
+_The Keeling Islands as Illustrating the Manner in which Oceanic Islands
+are Peopled._--That such causes as have been here adduced are those by
+which oceanic islands have been peopled, is further shown by the condition
+of equally remote islands which we know are of comparatively recent origin.
+Such are the Keeling or Cocos Islands in the Indian Ocean, situated about
+the same distance from Sumatra as the Galapagos from South America, but
+mere coral reefs, supporting abundance of cocoa-nut palms as their chief
+vegetation. These islands were visited by Mr. {286} Darwin, and their
+natural history carefully examined. The only mammals are rats, brought by a
+wrecked vessel and said by Mr. Waterhouse to be common English rats, "but
+smaller and more brightly coloured;" so that we have here an illustration
+of how soon a difference of race is established under a constant and
+uniform difference of conditions. There are no true land-birds, but there
+are snipes and rails, both apparently common Malayan species. Reptiles are
+represented by one small lizard, but no account of this is given in the
+_Zoology of the Voyage of the Beagle_, and we may therefore conclude that
+it was an introduced species. Of insects, careful collecting only produced
+thirteen species belonging to eight distinct orders. The only beetle was a
+small Elater, the Orthoptera were a Gryllus and a Blatta; and there were
+two flies, two ants, and two small moths, one a Diopæa which swarms
+everywhere in the eastern tropics in grassy places. All these insects were
+no doubt brought either by winds, by floating timber (which reaches the
+islands abundantly), or by clinging to the feathers of aquatic or wading
+birds; and we only require more time to introduce a greater variety of
+species, and a better soil and more varied vegetation, to enable them to
+live and multiply, in order to give these islands a fauna and flora equal
+to that of the Bermudas. Of wild plants there were only twenty species,
+belonging to nineteen genera and to no less than sixteen natural families,
+while all were common tropical shore plants.[62] These islands are thus
+evidently stocked by waifs and strays brought by the winds and waves; but
+their scanty vegetation is mainly due to unfavourable conditions--the
+barren coral rock and sand, of which they are wholly composed, together
+with exposure to sea-air, being suitable to a very limited number of
+species which soon monopolise the surface. With more variety of soil and
+aspect a greater variety of plants would establish themselves, and these
+would favour the preservation and increase of more insects, birds, and
+{287} other animals, as we find to be the case in many small and remote
+islands.[63]
+
+_Flora of the Galapagos._--The plants of these islands are so much more
+numerous than the known animals, even including the insects, they have been
+so carefully studied by eminent botanists, and their relations throw so
+much light on the past history of the group, that no apology is needed for
+giving a brief outline of the peculiarities and affinities of the flora.
+The statements we shall make on this subject will be taken from the Memoir
+of Sir Joseph Hooker in the _Linnæan Transactions_ for 1851, founded on Mr.
+Darwin's collections, and a later paper by N. J. Andersson in the _Linnæa_
+of 1861, embodying more recent discoveries. {288}
+
+The total number of flowering plants known at the latter date was 332, of
+which 174 were peculiar to the islands, while 158 were common to other
+countries.[64] Of these latter about twenty have been introduced by man,
+while the remainder are all natives of some part of America, though about a
+third part are species of wide range extending into both hemispheres. Of
+those confined to America, forty-two are found in both the northern and
+southern continents, twenty-one are confined to South America, while twenty
+are found only in North America, the West Indies, or Mexico. This equality
+of North American and South American species in the Galapagos is a fact of
+great significance in connection with the observation of Sir Joseph Hooker
+that the _peculiar_ species are allied to the plants of temperate America
+or to those of the high Andes, while the non-peculiar species are mostly
+such as inhabit the hotter regions of the tropics near the level of the
+sea. He also observes that the seeds of this latter class of Galapagos
+plants often have special means of transport, or belong to groups whose
+seeds are known to stand long voyages and to possess great vitality. Mr.
+Bentham also, in his elaborate account of the Compositæ,[65] remarks on the
+decided Central American or Mexican affinities of the Galapagos species, so
+that we may consider this to be a thoroughly well-established fact.
+
+The most prevalent families of plants in the Galapagos are the Compositæ
+(40 sp.), Gramineæ (32 sp.), Leguminosæ (30 sp.), and Euphorbiaceæ (29
+sp.). Of the Compositæ most of the species, except such as are common weeds
+or shore plants, are peculiar, but there are only two peculiar genera,
+allied to Mexican forms and not very distinct; while the genus Lipochæta,
+represented here by a single species, is only found elsewhere in the
+Sandwich Islands though it has American affinities.
+
+_Origin of the Galapagos Flora._--These facts are explained by the past
+history of the American continent, its {289} separation at various epochs
+by arms of the sea uniting the two oceans across what is now Central
+America (the last separation being of recent date, as shown by the
+considerable number of identical species of fishes on both sides of the
+isthmus), and the influence of the glacial epoch in driving the temperate
+American flora southward along the mountain plateaus.[66] At the time when
+the two oceans were united a portion of the Gulf Stream may have been
+diverted into the Pacific, giving rise to a current, some part of which
+would almost certainly have reached the Galapagos, and this may have helped
+to bring about that singular assemblage of West Indian and Mexican plants
+now found there. And as we now believe that the duration of the last
+glacial epoch in its successive phases was much longer than the time which
+has elapsed since it finally passed away, while throughout the Miocene
+epoch the snow-line would often be lowered during periods of high
+excentricity, we are enabled to comprehend the nature of the causes which
+may have led to the islands being stocked with those north tropical or
+mountain types which are so characteristic a feature of that portion of the
+Galapagos flora which consists of peculiar species.
+
+On the whole, the flora agrees with the fauna in indicating a moderately
+remote origin, great isolation, and changes of conditions affording
+facilities for the introduction of organisms from various parts of the
+American coast, and even from the West Indian Islands and Gulf of Mexico.
+As in the case of the birds, the several islands differ considerably in
+their native plants, many species being limited to one or two islands only,
+while others extend to several. This is, of course, what might be expected
+on any theory of their origin; because, even if the whole of the islands
+had once been united and afterwards separated, long continued isolation
+would often lead to the differentiation of species, while the varied
+conditions to be found upon islands differing in size and altitude as well
+as in luxuriance of vegetation, would often lead to the extinction of a
+species on one island and its preservation on another. If the several
+islands had been equally well {290} explored, it might be interesting to
+see whether, as in the case of the Azores, the number of species diminished
+in those more remote from the coast; but unfortunately our knowledge of the
+productions of the various islands of the group is exceedingly unequal,
+and, except in those cases in which representative species inhabit distinct
+islands, we have no certainty on the subject. All the more interesting
+problems in geographical distribution, however, arise from the relation of
+the fauna and flora of the group as a whole to those of the surrounding
+continents, and we shall therefore for the most part confine ourselves to
+this aspect of the question in our discussion of the phenomena presented by
+oceanic or continental islands.
+
+_Concluding Remarks._--The Galapagos offer an instructive contrast with the
+Azores, showing how a difference of conditions that might be thought
+unimportant may yet produce very striking results in the forms of life.
+Although the Galapagos are much nearer a continent than the Azores, the
+number of species of plants common to the continent is much less in the
+former case than in the latter, and this is still more prominent a
+characteristic of the insect and the bird faunas. This difference has been
+shown to depend, almost entirely, on the one archipelago being situated in
+a stormy, the other in a calm portion of the ocean; and it demonstrates the
+preponderating importance of the atmosphere as an agent in the dispersal of
+birds, insects, and plants. Yet ocean-currents and surface-drifts are
+undoubtedly efficient carriers of plants, and, with plants, of insects and
+shells, especially in the tropics; and it is probably to this agency that
+we may impute the recent introduction of a number of common Peruvian and
+Chilian littoral species, and also of several West Indian types at a more
+remote period when the Isthmus of Panama was submerged.
+
+In the case of these islands we see the importance of taking account of
+past conditions of sea and land and past changes of climate, in order to
+explain the relations of the peculiar or endemic species of their fauna and
+flora; and we may even see an indication of the effects of climatal changes
+in the northern hemisphere, in the north {291} temperate or alpine
+affinities of many of the plants, and even of some of the birds. The
+relation between the migratory habits of the birds and the amount of
+difference from continental types is strikingly accordant with the fact
+that it is almost exclusively migratory birds that annually reach the
+Azores and Bermuda; while the corresponding fact that the seeds of those
+plants, which are common to the Galapagos and the adjacent continent, have
+all--as Sir Joseph Hooker states--some special means of dispersal, is
+equally intelligible. The reason why the Galapagos possess four times as
+many peculiar species of plants as the Azores is clearly a result of the
+less constant introduction of seeds, owing to the absence of storms; the
+greater antiquity of the group, allowing more time for specific change; and
+the influence of cold epochs and of alterations of sea and land, in
+bringing somewhat different sets of plants at different times within the
+influence of such modified winds and currents as might convey them to the
+islands.
+
+On the whole, then, we have no difficulty in explaining the probable origin
+of the flora and fauna of the Galapagos, by means of the illustrative facts
+and general principles already adduced.
+
+ * * * * *
+
+
+{292}
+
+CHAPTER XIV
+
+ST. HELENA
+
+ Position and Physical Features of St. Helena--Change Effected by
+ European Occupation--The Insects of St.
+ Helena--Coleoptera--Peculiarities and Origin of the Coleoptera of St.
+ Helena--Land-shells of St. Helena--Absence of Fresh-water
+ Organisms--Native Vegetation of St. Helena--The Relations of the St.
+ Helena Compositæ--Concluding Remarks on St. Helena.
+
+In order to illustrate as completely as possible the peculiar phenomena of
+oceanic islands, we will next examine the organic productions of St. Helena
+and of the Sandwich Islands, since these combine in a higher degree than
+any other spots upon the globe, extreme isolation from all more extensive
+lands, with a tolerably rich fauna and flora whose peculiarities are of
+surpassing interest. Both, too, have received considerable attention from
+naturalists; and though much still remains to be done in the latter group,
+our knowledge is sufficient to enable us to arrive at many interesting
+results.
+
+{293} [Illustration: MAP OF THE SOUTH ATLANTIC OCEAN SHOWING THE POSITION
+OF ST. HELENA.]
+
+ The light tint shows depths of less than 1,000 fathoms.
+ The figures show depths of the sea in fathoms.
+
+_Position and Physical Features of St. Helena._--This island is situated
+nearly in the middle of the South Atlantic Ocean, being more than 1,100
+miles from the coast of Africa, and 1,800 from South America. It is about
+ten miles long by eight wide, and is wholly volcanic, consisting of ancient
+basalts, lavas, and other volcanic products. It is very mountainous and
+rugged, bounded for {294} the most part by enormous precipices, and rising
+to a height of 2,700 feet above the sea-level. An ancient crater, about
+four miles across, is open on the south side, and its northern rim forms
+the highest and central ridge of the island. Many other hills and peaks,
+however, are more than two thousand feet high, and a considerable portion
+of the surface consists of a rugged plateau, having an elevation of about
+fifteen hundred to two thousand feet. Everything indicates that St. Helena
+is an isolated volcanic mass built up from the depths of the ocean. Mr.
+Wollaston remarks: "There are the strongest reasons for believing that the
+area of St. Helena was never _very_ much larger than it is at present--the
+comparatively shallow sea-soundings within about a mile and a half from the
+shore revealing an abruptly defined ledge, _beyond_ which no bottom is
+reached at a depth of 250 fathoms; so that the original basaltic mass,
+which was gradually piled up by means of successive eruptions from beneath
+the ocean, would appear to have its limit definitely marked out by this
+suddenly-terminating submarine cliff--the space between it and the existing
+coast-line being reasonably referred to that slow process of disintegration
+by which the island has been reduced, through the eroding action of the
+elements, to its present dimensions." If we add to this that between the
+island and the coast of Africa, in a south-easterly direction, is a
+profound oceanic gulf known to reach a depth of 2,860 fathoms, or 17,160
+feet, while an equally deep, or perhaps deeper, ocean, extends to the west
+and south-west, we shall be satisfied that St. Helena is a true oceanic
+island, and that it owes none of its peculiarities to a former union with
+any continent or other distant land.
+
+_Change Effected by European Occupation._--When first discovered, in the
+year 1501, St. Helena was densely covered with a luxuriant forest
+vegetation, the trees overhanging the seaward precipices and covering every
+part of the surface with an evergreen mantle. This indigenous vegetation
+has been almost wholly destroyed; and although an immense number of foreign
+plants have been introduced, and have more or less completely established
+themselves, {295} yet the general aspect of the island is now so barren and
+forbidding that some persons find it difficult to believe that it was once
+all green and fertile. The cause of the change is, however, very easily
+explained. The rich soil formed by decomposed volcanic rock and vegetable
+deposits could only be retained on the steep slopes so long as it was
+protected by the vegetation to which it in great part owed its origin. When
+this was destroyed, the heavy tropical rains soon washed away the soil, and
+has left a vast expanse of bare rock or sterile clay. This irreparable
+destruction was caused in the first place by goats, which were introduced
+by the Portuguese in 1513, and increased so rapidly that in 1588, they
+existed in thousands. These animals are the greatest of all foes to trees,
+because they eat off the young seedlings, and thus prevent the natural
+restoration of the forest. They were, however, aided by the reckless waste
+of man. The East India Company took possession of the island in 1651, and
+about the year 1700 it began to be seen that the forests were fast
+diminishing, and required some protection. Two of the native trees, redwood
+and ebony, were good for tanning, and to save trouble the bark was
+wastefully stripped from the trunks only, the remainder being left to rot;
+while in 1709 a large quantity of the rapidly disappearing ebony was used
+to burn lime for building fortifications! By the MSS. records quoted in Mr.
+Melliss' interesting volume on St. Helena,[67] it is evident that the evil
+consequences of allowing the trees to be destroyed were clearly foreseen,
+as the following passages show: "We find the place called the Great Wood in
+a flourishing condition, full of young trees, where the hoggs (of which
+there is a great abundance) do not come to root them up. But the Great Wood
+is miserably lessened and destroyed within our memories, and is not near
+the circuit and length it was. But we believe it does not contain now less
+than fifteen hundred acres of fine woodland and good ground, but no springs
+of water but what is salt or brackish, which we take to be the reason that
+that part was not inhabited when the people first {296} chose out their
+settlements and made plantations; but if wells could be sunk, which the
+governor says he will attempt when we have more hands, we should then think
+it the most pleasant and healthiest part of the island. But as to
+healthiness, we don't think it will hold so if the wood that keeps the land
+warm were destroyed, for then the rains, which are violent here, would
+carry away the upper soil, and it being a clay marl underneath would
+produce but little; as it is, we think in case it were enclosed it might be
+greatly improved" ... "When once this wood is gone the island will soon be
+ruined" ... "We viewed the wood's end which joins the Honourable Company's
+plantation called the Hutts, but the wood is so destroyed that the
+beginning of the Great Wood is now a whole mile beyond that place, and all
+the soil between being washed away, that distance is now entirely barren."
+(MSS. records, 1716.) In 1709 the governor reported to the Court of
+Directors of the East India Company that the timber was rapidly
+disappearing, and that the goats should be destroyed for the preservation
+of the ebony wood, and because the island was suffering from droughts. The
+reply was, "The goats are not to be destroyed, being more valuable than
+ebony." Thus, through the gross ignorance of those in power, the last
+opportunity of preserving the peculiar vegetation of St. Helena, and
+preventing the island from becoming the comparatively rocky desert it now
+is, was allowed to pass away.[68] Even in a mere {297} pecuniary point of
+view the error was a fatal one, for in the next century (in 1810) another
+governor reports the total destruction of the great forests by the goats,
+and that in consequence the cost of importing fuel for government use was
+2,729l. 7s. 8d. for a single year! About this time large numbers of
+European, American, Australian, and South African plants were imported, and
+many of these ran wild and increased so rapidly as to drive out and
+exterminate much of the relics of the native flora; so that now English
+broom gorse and brambles, willows and poplars, and some common American,
+Cape, and Australian weeds, alone meet the eye of the ordinary visitor.
+These, in Sir Joseph Hooker's opinion, render it absolutely impossible to
+restore the native flora, which only lingers in a few of the loftiest
+ridges and most inaccessible precipices, and is rarely seen except by some
+exploring naturalist.
+
+This almost total extirpation of a luxuriant and highly peculiar vegetation
+must inevitably have caused the destruction of a considerable portion of
+the lower animals which once existed on the island, and it is rather
+singular that so much as has actually been discovered should be left to
+show us the nature of the aboriginal fauna. Many naturalists have made
+small collections during short visits, but we owe our present complete
+knowledge of the two most interesting groups of animals, the insects, and
+the land-shells, mainly to the late Mr. T. Vernon Wollaston, who, after
+having thoroughly explored Madeira and the Canaries, undertook a voyage to
+St. Helena for the express purpose of studying its terrestrial fauna, and
+resided for six months (1875-76) in a high central position, whence the
+loftiest peaks could be explored. The results of his labours are contained
+in two volumes,[69] which, like all that he wrote, are models of accuracy
+and research, and it is to these volumes that we are indebted for the
+interesting and suggestive facts which we here lay before our readers.
+
+{298}
+
+_Insects--Coleoptera._--The total number of species of beetles hitherto
+observed at St. Helena is 203, but of these no less than seventy-four are
+common and wide-spread insects, which have certainly, in Mr. Wollaston's
+opinion, been introduced by human agency. There remain 129 which are
+believed to be truly aborigines, and of these all but one are found nowhere
+else on the globe. But in addition to this large amount of specific
+peculiarity (perhaps unequalled anywhere else in the world) the beetles of
+this island are equally remarkable for their generic isolation, and for the
+altogether exceptional proportion in which the great divisions of the order
+are represented. The species belong to thirty-nine genera, of which no less
+than twenty-five are peculiar to the island; and many of these are such
+isolated forms that it is impossible to find their allies in any particular
+country. Still more remarkable is the fact, that more than two-thirds of
+the whole number of indigenous species are Rhyncophora or weevils, while
+more than two-fifths (fifty-four species) belong to one family, the
+Cossonidæ. Now although the Rhyncophora are an immensely numerous group and
+always form a large portion of the insect population, they nowhere else
+approach such a proportion as this. For example, in Madeira they form
+one-sixth of the whole of the indigenous Coleoptera, in the Azores less
+than one-tenth, and in Britain one-seventh. Even more interesting is the
+fact that the twenty genera to which these insects belong are every one of
+them peculiar to the island, and in many cases have no near allies
+elsewhere, so that we cannot but look on this group of beetles as forming
+the most characteristic portion of the ancient insect fauna. Now, as the
+great majority of these are wood borers, and all are closely attached to
+vegetation and often to particular species of plants, we might, as Mr.
+Wollaston well observes, deduce the former luxuriant vegetation of the
+island from the great preponderance of this group, even had we not positive
+evidence that it was at no distant epoch densely forest-clad. We will now
+proceed briefly to indicate the numbers and peculiarities of each of the
+families of beetles which enter into the St. Helena fauna, taking them, not
+in {299} systematic order, but according to their importance in the island.
+
+1. RHYNCOPHORA.--This great division includes the weevils and allied
+groups, and, as above stated, exceeds in number of species all the other
+beetles of the island. Four families are represented; the Cossonidæ, with
+fifteen peculiar genera comprising fifty-four species, and one minute
+insect (_Stenoscelis hylastoides_) forming a peculiar genus, but which has
+been found also at the Cape of Good Hope. It is therefore impossible to say
+of which country it is really a native, or whether it is indigenous to
+both, and dates back to the remote period when St. Helena received its
+early emigrants. All the Cossonidæ are found in the highest and wildest
+parts of the island where the native vegetation still lingers, and many of
+them are only found in the decaying stems of tree-ferns, box-wood,
+arborescent Compositæ, and other indigenous plants. They are all
+pre-eminently peculiar and isolated, having no direct affinity to species
+found in any other country. The next family, the Tanyrhynchidæ, has one
+peculiar genus in St. Helena, with ten species. This genus (Nesiotes) is
+remotely allied to European, Australian, and Madeiran insects of the same
+family: the habits of the species are similar to those of the Cossonidæ.
+The Trachyphloeidæ are represented by a single species belonging to a
+peculiar genus not very remote from a European form. The Anthribidæ again
+are highly peculiar. There are twenty-six species belonging to three
+genera, all endemic, and so extremely peculiar that they form two new
+subfamilies. One of the genera, Acarodes, is said to be allied to a
+Madeiran genus.
+
+2. GEODEPHAGA.--These are the terrestrial carnivorous beetles, very
+abundant in all parts of the world, especially in the temperate regions of
+the northern hemisphere. In St. Helena there are fourteen species belonging
+to three genera, one of which is peculiar. This is the _Haplothorax
+burchellii_, the largest beetle on the island, and now very rare. It
+resembles a large black Carabus. There is also a peculiar Calosoma, very
+distinct, though resembling in some respects certain African species. The
+rest of the {300} Geodephaga, twelve in number, belong to the wide-spread
+genus Bembidium, but they are altogether peculiar and isolated, except one,
+which is of European type, and alone has wings, all the rest being
+wingless.
+
+3. HETEROMERA.--This group is represented by three peculiar genera
+containing four species, with two species belonging to European genera.
+They belong to the families Opatridæ, Mordellidæ, and Anthicidæ.
+
+4. BRACHYELYTRA.--Of this group there are six peculiar species belonging to
+four European genera--Homalota, Philonthus, Xantholinus, and Oxytelus.
+
+5. PRIOCERATA.--The families Elateridæ and Anobiidæ are each represented by
+a peculiar species of a European genus.
+
+6. PHYTOPHAGA.--There are only three species of this tribe, belonging to
+the European genus Longitarsus.
+
+7. LAMELLICORNIS.--Here are three species belonging to two genera. One is a
+peculiar species of Trox, allied to South African forms; the other two
+belong to the peculiar genus Melissius, which Mr. Wollaston considers to be
+remotely allied to Australian insects.
+
+8. PSEUDO-TRIMERA.--Here we have the fine lady-bird _Chilomenus lunata_,
+also found in Africa, but apparently indigenous in St. Helena; and a
+peculiar species of Euxestes, a genus only found elsewhere in Madeira.
+
+9. TRICHOPTERYGIDÆ.--These, the minutest of beetles, are represented by one
+species of the European and Madeiran genus Ptinella.
+
+10. NECROPHAGA.--One indigenous species of Cryptophaga inhabits St. Helena,
+and this is said to be very closely allied to a Cape species.
+
+_Peculiarities and Origin of the Coleoptera of St. Helena._--We see that
+the great mass of the indigenous species are not only peculiar to the
+island, but so isolated in their characters as to show no close affinity
+with any existing insects; while a small number (about one-third of the
+whole) have some relations, though often very remote, with species now
+inhabiting Europe, Madeira, or South Africa. These facts clearly point to
+the very great antiquity of the insect fauna of St. Helena, which has
+allowed {301} time for the modification of the originally introduced
+species, and their special adaptation to the conditions prevailing in this
+remote island. This antiquity is also shown by the remarkable specific
+modification of a few types. Thus the whole of the Cossonidæ may be
+referred to three types, one species only (_Hexacoptus ferrugineus_) being
+allied to the European Cossonidæ though forming a distinct genus; a group
+of three genera and seven species remotely allied to the _Stenoscelis
+hylastoides_, which occurs also at the Cape; while a group of twelve genera
+with forty-six species have their only (remote) allies in a few insects
+widely scattered in South Africa, New Zealand, Europe, and the Atlantic
+Islands. In like manner, eleven species of Bembidium form a group by
+themselves; and the Heteromera form two groups, one consisting of three
+genera and species of Opatridæ allied to a type found in Madeira, the
+other, Anthicodes, altogether peculiar.
+
+Now each of these types may well be descended from a single species which
+originally reached the island from some other land; and the great variety
+of generic and specific forms into which some of them have diverged is an
+indication, and to some extent a measure, of the remoteness of their
+origin. The rich insect fauna of Miocene age found in Switzerland consists
+mostly of genera which still inhabit Europe, with others which now inhabit
+the Cape of Good Hope or the tropics of Africa and South America; and it is
+not at all improbable that the origin of the St. Helena fauna dates back to
+at least as remote, and not improbably to a still earlier, epoch. But if
+so, many difficulties in accounting for its origin will disappear. We know
+that at that time many of the animals and plants of the tropics, of North
+America, and even of Australia, inhabited Europe; while during the changes
+of climate, which, as we have seen, there is good reason to believe
+periodically occurred, there would be much migration from the temperate
+zones towards the equator, and the reverse. If, therefore, the nearest ally
+of any insular group now inhabits a particular country, we are not obliged
+to suppose that it reached the island from that country, since we know that
+most groups have ranged in past times over {302} wider areas than they now
+inhabit. Neither are we limited to the means of transmission across the
+ocean that now exist, because we know that those means have varied greatly.
+During such extreme changes of conditions as are implied by glacial periods
+and by warm polar climates, great alterations of winds and of
+ocean-currents are inevitable, and these are, as we have already proved,
+the two great agencies by which the transmission of living things to
+oceanic islands has been brought about. At the present time the south-east
+trade-winds blow almost constantly at St. Helena, and the ocean-currents
+flow in the same direction, so that any transmission of insects by their
+means must almost certainly be from South Africa. Now there is undoubtedly
+a South African element in the insect-fauna, but there is no less clearly a
+European, or at least a north-temperate element, and this is very difficult
+to account for by causes now in action. But when we consider that this
+northern element is chiefly represented by remote generic affinity, and has
+therefore all the signs of great antiquity, we find a possible means of
+accounting for it. We have seen that during early Tertiary times an almost
+tropical climate extended far into the northern hemisphere, and a temperate
+climate to the Arctic regions. But if at this time (as is not improbable)
+the Antarctic regions were as much ice-clad as they are now it is certain
+that an enormous change must have been produced in the winds. Instead of a
+great difference of temperature between each pole and the equator, the
+difference would be mainly between one hemisphere and the other, and this
+might so disturb the trade winds as to bring St. Helena within the south
+temperate region of storms--a position corresponding to that of the Azores
+and Madeira in the North Atlantic, and thus subject it to violent gales
+from all points of the compass. At this remote epoch the mountains of
+equatorial Africa may have been more extensive than they are now, and may
+have served as intermediate stations by which some northern insects may
+have migrated to the southern hemisphere.
+
+We must remember also that these peculiar forms are said to be northern
+only because their nearest allies are {303} now found in the North Atlantic
+islands and Southern Europe; but it is not at all improbable that they are
+really widespread Miocene types, which have been preserved mainly in
+favourable insular stations. They may therefore have originally reached St.
+Helena from Southern Africa, or from some of the Atlantic islands, and may
+have been conveyed by oceanic currents as well as by winds.[70] This is the
+more probable, as a large proportion of the St. Helena beetles live even in
+the perfect state within the stems of plants or trunks of trees, while the
+eggs and larvæ of a still larger number are likely to inhabit similar
+stations. Drift-wood might therefore be one of the most important agencies
+by which these insects reached the island.
+
+Let us now see how far the distribution of other groups support the
+conclusions derived from a consideration of the beetles. The Hemiptera have
+been studied by Dr. F. Buchanan White, and though far less known than the
+beetles, indicate somewhat similar relations. Eight out of twenty-one
+genera are peculiar, and the thirteen other genera are for the most part
+widely distributed, while one of the peculiar genera is of African type.
+The other orders of insects have not been collected or studied with {304}
+sufficient care to make it worth while to refer to them in detail; but the
+land-shells have been carefully collected and minutely described by Mr.
+Wollaston himself, and it is interesting to see how far they agree with the
+insects in their peculiarities and affinities.
+
+_Land-shells of St. Helena._--The total number of species is only
+twenty-nine, of which seven are common in Europe or the other Atlantic
+islands, and are no doubt recent introductions. Two others, though
+described as distinct, are so closely allied to European forms, that Mr.
+Wollaston thinks they have probably been introduced and have become
+slightly modified by new conditions of life; so that there remain exactly
+twenty species which may be considered truly indigenous. No less than
+thirteen of these, however, appear to be extinct, being now only found on
+the surface of the ground or in the surface soil in places where the native
+forests have been destroyed and the land not cultivated. These twenty
+peculiar species belong to the following genera: Hyalina (3 sp.), Patula (4
+sp.), Bulimus (7 sp.), Subulina (3 sp.), Succinea (3 sp.); of which, one
+species of Hyalina, three of Patula, all the Bulimi, and two of Subulina
+are extinct. The three Hyalinas are allied to European species, but all the
+rest appear to be highly peculiar, and to have no near allies with the
+species of any other country. Two of the Bulimi (_B. auris vulpinæ_ and _B.
+darwinianus_) are said to somewhat resemble Brazilian, New Zealand, and
+Solomon Island forms, while neither Bulimus nor Succinea occur at all in
+the Madeira group.
+
+Omitting the species that have probably been introduced by human agency, we
+have here indications of a somewhat recent immigration of European types
+which may perhaps be referred to the glacial period; and a much more
+ancient immigration from unknown lands, which must certainly date back to
+Miocene, if not to Eocene, times.
+
+_Absence of Fresh-water Organisms._--A singular phenomenon is the total
+absence of indigenous aquatic forms of life in St. Helena. Not a single
+water-beetle or fresh-water shell has been discovered; neither do there
+seem to be any water-plants in the streams, except the common {305}
+water-cress, one or two species of Cyperus, and the Australian _Isapis
+prolifera_. The same absence of fresh-water shells characterises the
+Azores, where, however, there is one indigenous water-beetle. In the
+Sandwich Islands also recent observations refer to the absence of
+water-beetles, though here there are a few fresh-water shells. It would
+appear therefore that the wide distribution of the same generic and
+specific forms which so generally characterises fresh-water organisms, and
+which has been so well illustrated by Mr. Darwin, has its limits in the
+_very remote_ oceanic islands, owing to causes of which we are at present
+ignorant.
+
+The other classes of animals in St. Helena need occupy us little. There are
+no indigenous mammals, reptiles, fresh-water fishes or true land-birds; but
+there is one species of wader--a small plover (_Ægialitis
+sanctæ-helenæ_)--very closely allied to a species found in South Africa,
+but presenting certain differences which entitle it to the rank of a
+peculiar species. The plants, however, are of especial interest from a
+geographical point of view, and we must devote a few pages to their
+consideration as supplementing the scanty materials afforded by the animal
+life, thus enabling us better to understand the biological relations and
+probable history of the island.
+
+_Native Vegetation of St. Helena._--Plants have certainly more varied and
+more effectual means of passing over wide tracts of ocean than any kinds of
+animals. Their seeds are often so minute, of such small specific gravity,
+or so furnished with downy or winged appendages, as to be carried by the
+wind for enormous distances. The bristles or hooked spines of many small
+fruits cause them to become easily attached to the feathers of aquatic
+birds, and they may thus be conveyed for thousands of miles by these
+pre-eminent wanderers; while many seeds are so protected by hard outer
+coats and dense inner albumen, that months of exposure to salt water does
+not prevent them from germinating, as proved by the West Indian seeds that
+reach the Azores or even the west coast of Scotland, and, what is more to
+the point, by the fact stated by Mr. Melliss, that large seeds which have
+floated from {306} Madagascar or Mauritius round the Cape of Good Hope,
+have been thrown on the shores of St. Helena and have then sometimes
+germinated!
+
+We have therefore little difficulty in understanding _how_ the island was
+first stocked with vegetable forms. _When_ it was so stocked (generally
+speaking), is equally clear. For as the peculiar coleopterous fauna, of
+which an important fragment remains, is mainly composed of species which
+are specially attached to certain groups of plants, we may be sure that the
+plants were there long before the insects could establish themselves.
+However ancient then is the insect fauna the flora must be more ancient
+still. It must also be remembered that plants, when once established in a
+suitable climate and soil, soon take possession of a country and occupy it
+almost to the complete exclusion of later immigrants. The fact of so many
+European weeds having overrun New Zealand and temperate North America may
+seem opposed to this statement, but it really is not so. For in both these
+cases the native vegetation has first been artificially removed by man and
+the ground cultivated; and there is no reason to believe that any similar
+effect would be produced by the scattering of any amount of foreign seed on
+ground already completely clothed with an indigenous vegetation. We might
+therefore conclude _à priori_, that the flora of such an island as St.
+Helena would be of an excessively ancient type, preserving for us in a
+slightly modified form examples of the vegetation of the globe at the time
+when the island first rose above the ocean. Let us see then what botanists
+tell us of its character and affinities.
+
+The truly indigenous flowering plants are about fifty in number, besides
+twenty-six ferns. Forty of the former and ten of the latter are absolutely
+peculiar to the island, and, as Sir Joseph Hooker tells us, "with scarcely
+an exception, cannot be regarded as very close specific allies of any other
+plants at all. Seventeen of them belong to peculiar genera, and of the
+others, all differ so markedly as species from their congeners, that not
+one comes under the category of being an insular form of a continental
+species." The affinities of this flora are, Sir Joseph Hooker thinks, {307}
+mainly African and especially South African, as indicated by the presence
+of the genera Phylica, Pelargonium, Mesembryanthemum, Oteospermum, and
+Wahlenbergia, which are eminently characteristic of southern extra-tropical
+Africa. The sixteen ferns which are not peculiar are common either to
+Africa, India, or America, a wide range sufficiently explained by the
+dust-like spores of ferns, capable of being carried to unknown distances by
+the wind, and the great stability of their generic and specific forms, many
+of those found in the Miocene deposits of Switzerland, being hardly
+distinguishable from living species. This shows, that identity of _species_
+of ferns between St. Helena and distant countries does not necessarily
+imply a recent origin.
+
+_The Relation of the St. Helena Compositæ._--In an elaborate paper on the
+Compositæ,[71] Mr. Bentham gives us some valuable remarks on the affinities
+of the seven endemic species belonging to the genera Commidendron,
+Melanodendron, Petrobium, and Pisiadia, which forms so important a portion
+of the existing flora of St. Helena. He says: "Although nearer to Africa
+than to any other continent, those composite denizens which bear evidence
+of the greatest antiquity have their affinities for the most part in South
+America, while the colonists of a more recent character are South African."
+... "Commidendron and Melanodendron are among the woody Asteroid forms
+exemplified in the Andine Diplostephium, and in the Australian Olearia.
+Petrobium is one of three genera, remains of a group probably of great
+antiquity, of which the two others are Podanthus in Chile and Astemma in
+the Andes. The Pisiadia is an endemic species of a genus otherwise
+Mascarene or of Eastern Africa, presenting a geographical connection
+analogous to that of the St. Helena Melhaniæ,[72] with the Mascarene
+Trochetia."
+
+Whenever such remote and singular cases of geographical affinity as the
+above are pointed out, the first {308} impression is to imagine some mode
+by which a communication between the distant countries implicated might be
+effected; and this way of viewing the problem is almost universally
+adopted, even by naturalists. But if the principles laid down in this work
+and in my _Geographical Distribution of Animals_ are sound, such a course
+is very unphilosophical. For, on the theory of evolution, nothing can be
+more certain than that groups now broken up and detached were once
+continuous, and that fragmentary groups and isolated forms are but the
+relics of once widespread types, which have been preserved in a few
+localities where the physical conditions were especially favourable, or
+where organic competition was less severe. The true explanation of all such
+remote geographical affinities is, that they date back to a time when the
+ancestral group of which they are the common descendants had a wider or a
+different distribution; and they no more imply any closer connection
+between the distant countries the allied forms now inhabit, than does the
+existence of living Equidæ in South Africa and extinct Equidæ in the
+Pliocene deposits of the Pampas, imply a continent bridging the South
+Atlantic to allow of their easy communication.
+
+_Concluding Remarks on St. Helena._--The sketch we have now given of the
+chief members of the indigenous fauna and flora of St. Helena shows, that
+by means of the knowledge we have obtained of past changes in the physical
+history of the earth, and of the various modes by which organisms are
+conveyed across the ocean, all the more important facts become readily
+intelligible. We have here an island of small size and great antiquity,
+very distant from every other land, and probably at no time very much less
+distant from surrounding continents, which became stocked by chance
+immigrants from other countries at some remote epoch, and which has
+preserved many of their more or less modified descendants to the present
+time. When first visited by civilised man it was in all probability far
+more richly stocked with plants and animals, forming a kind of natural
+museum or vivarium in which ancient types, perhaps dating back to the
+Miocene {309} period, or even earlier, had been saved from the destruction
+which has overtaken their allies on the great continents. Unfortunately
+many, we do not know how many, of these forms have been exterminated by the
+carelessness and improvidence of its civilised but ignorant rulers; and it
+is only by the extreme ruggedness and inaccessibility of its peaks and
+crater-ridges that the scanty fragments have escaped by which alone we are
+able to obtain a glimpse of this interesting chapter in the life-history of
+our earth.
+
+ * * * * *
+
+
+{310}
+
+CHAPTER XV
+
+THE SANDWICH ISLANDS
+
+ Position and Physical Features--Zoology of the Sandwich
+ Islands--Birds--Reptiles--Land-shells--Insects--Vegetation of the
+ Sandwich Islands--Peculiar Features of the Hawaiian Flora--Antiquity of
+ the Hawaiian Fauna and Flora--Concluding Observations on the Fauna and
+ Flora of the Sandwich Islands--General Remarks on Oceanic Islands.
+
+The Sandwich Islands are an extensive group of large islands situated in
+the centre of the North Pacific, being 2,350 miles from the nearest part of
+the American coast--the bay of San Francisco, and about the same distance
+from the Marquesas and the Samoa Islands to the south, and the Aleutian
+Islands a little west of north. They are, therefore, wonderfully isolated
+in mid-ocean, and are only connected with the other Pacific Islands by
+widely scattered coral reefs and atolls, the nearest of which, however, are
+six or seven hundred miles distant, and are all nearly destitute of animal
+or vegetable life. The group consists of seven large inhabited islands
+besides four rocky islets; the largest, Hawaii, being seventy miles across
+and having an area 3,800 square miles--being somewhat larger than all the
+other islands together. A better conception of this large island will be
+formed by comparing it with Devonshire, with which it closely agrees both
+in size and shape, though its enormous volcanic mountains rise to nearly
+14,000 feet high. {311} Three of the smaller islands are each about the
+size of Hertfordshire or Bedfordshire, and the whole group stretches from
+north-west to south-east for a distance of about 350 miles. Though so
+extensive, the entire archipelago is volcanic, and the largest island is
+rendered sterile and comparatively uninhabitable by its three active
+volcanoes and their widespread deposits of lava.
+
+[Illustration: MAP OF THE SANDWICH ISLANDS.]
+
+ The light tint shows where the sea is less than 1,000 fathoms deep.
+ The figures show the depth in fathoms.
+
+The ocean depths by which these islands are separated from the nearest
+continents are enormous. North, east, and south, soundings have been
+obtained a little over or under three thousand fathoms, and these profound
+deeps extend over a large part of the North Pacific. We may {312} be quite
+sure, therefore, that the Sandwich Islands have, during their whole
+existence, been as completely severed from the great continents as they are
+now; but on the west and south there is a possibility of more extensive
+islands having existed, serving as stepping-stones to the island groups of
+the Mid-Pacific. This is indicated by a few widely-scattered coral islets,
+around which extend {313} considerable areas of less depth, varying from
+two hundred to a thousand fathoms, and which _may_ therefore indicate the
+sites of submerged islands of considerable extent. When we consider that
+east of New Zealand and New Caledonia, all the larger and loftier islands
+are of volcanic origin, with no trace of any ancient stratified rocks
+(except, perhaps, in the Marquesas, where, according to Jules Marcou,
+granite and gneiss are said to occur) it seems probable that the
+innumerable coral-reefs and atolls, which occur in groups on deeply
+submerged banks, mark the sites of bygone volcanic islands, similar to
+those which now exist, but which, after becoming extinct, have been lowered
+or destroyed by denudation, and finally have altogether disappeared except
+where their sites are indicated by the upward-growing coral-reefs. If this
+view is correct we should give up all idea of there ever having been a
+Pacific continent, but should look upon that vast ocean as having from the
+remotest geological epochs been the seat of volcanic forces, which from its
+profound depths have gradually built up the islands which now dot its
+surface, as well as many others which have sunk beneath its waves. The
+number of islands, as well as the total quantity of land-surface, may
+sometimes have been greater than it is now, and may thus have facilitated
+the transfer of organisms from one group to another, and more rarely even
+from the American, Asiatic, or Australian continents. Keeping these various
+facts and considerations in view, we may now proceed to examine the fauna
+and flora of the Sandwich Islands, and discuss the special phenomena they
+present.
+
+[Illustration: MAP OF THE NORTH PACIFIC WITH ITS SUBMERGED BANKS.]
+
+ The light tint shows where the sea is less than 1,000 fathoms deep.
+ The dark tint ,, ,, ,, more than 1,000 fathoms deep.
+ The figures show the depths in fathoms.
+
+_Zoology of the Sandwich Islands: Birds._--It need hardly be said that
+indigenous mammalia are quite unknown in the Sandwich Islands, the most
+interesting of the higher animals being the birds, which are tolerably
+numerous and highly peculiar. Many aquatic and wading birds which range
+over the whole Pacific visit these islands, twenty-five species having been
+observed, but even of these six are peculiar--a coot, _Fulica alai_; a
+moorhen, _Gallinula galeata_ var _sandvichensis_; a rail with rudimentary
+wings, _Pennula millei_; a stilt-plover, _Himantopus knudseni_; and {314}
+two ducks, _Anas Wyvilliana_ and _Bernicla sandvichensis_. The birds of
+prey are also great wanderers. Four have been found in the islands--the
+short-eared owl, _Otus brachyotus_, which ranges over the greater part of
+the globe, but is here said to resemble the variety found in Chile and the
+Galapagos; the barn owl, _Strix flammea_, of a variety common in the
+Pacific; a peculiar sparrow-hawk, _Accipiter hawaii_; and _Buteo
+solitarius_, a buzzard of a peculiar species, and coloured so as to
+resemble a hawk of the American subfamily Polyborinæ. It is to be noted
+that the genus Buteo abounds in America, but is not found in the Pacific;
+and this fact, combined with the remarkable colouration, renders it almost
+certain that this peculiar species is of American origin.
+
+The Passeres, or true perching birds, are especially interesting, being all
+of peculiar species, and, all but one, belonging to peculiar genera. Their
+numbers have been greatly increased since the first edition of this work
+appeared, partly by the exertions of American naturalists, and very largely
+by the researches of Mr. Scott B. Wilson, who visited the Sandwich Islands
+for the purpose of investigating their ornithology, and collected
+assiduously in the various islands of the group for a year and a half. This
+gentleman is now publishing a finely illustrated work on Hawaiian birds,
+and he has kindly furnished me with the following list.
+
+ PASSERES OF THE SANDWICH ISLANDS.
+
+ MUSCICAPIDÆ (Flycatchers).
+
+ 1. _Chasiempis ridgwayi_ Hawaii.
+ 2. ,, _sclateri_ Kauai.
+ 3. ,, _dolei_ Kauai.
+ 4. ,, _gayi_ Oahu.
+ 5. ,, _ibidis_ Oahu.
+ 6. _Phæornis obscura_ Hawaii.
+ 7. ,, _myadestina_ Kauai.
+
+ MELIPHAGIDÆ (Honeysuckers).
+
+ 8. _Acrulocercus nobilis_ Hawaii.
+ 9. ,, _braccalus_ Kauai.
+ 10. ,, _apicalis_ (extinct) Oahu or Maui.
+ 11. _Chætoptila angustipluma_ (extinct) Hawaii.
+ {315}
+
+ DREPANIDIDÆ.
+
+ 12. _Drepanis pacifica_ (extinct) Hawaii.
+ 13. _Vastiaria coccinea_ All the Islands.
+ 14. _Hiniatione vireus_ Hawaii.
+ 15. ,, _dolii_ Maui.
+ 16. ,, _sanguinea_ All the Islands.
+ 17. ,, _montana_ Lanai.
+ 18. ,, _chloris_ Oahu.
+ 19. ,, _maculata_ Oahu.
+ 20. ,, _parva_ Kauai.
+ 21. ,, _stejnegeri_ Kauai.
+ 22. _Oreomyza bairdi_ Kauai.
+ 23. _Hemignathus obscurus_ Hawaii.
+ 24. ,, _olivaceus_ Hawaii.
+ 25. ,, _lichtensteini_ Oahu.
+ 26. ,, _lucidus_ Oahu.
+ 27. ,, _stejnegeri_ Kauai.
+ 28. ,, _hanapepe_ Kauai.
+ 29. _Loxops coccinea_ Hawaii.
+ 30. ,, _flammea_ Molokai.
+ 31. ,, _aurea_ Maui.
+ 32. _Chrysomitridops coeruleorostris_ Kaui.
+ 33. ,, _anna_ (extinct)
+
+ FRINGILLIDÆ (Finches).
+
+ 34. _Loxioides bailleni_ Hawaii.
+ 35. _Psittirostra psittacea_ All the Islands.
+ 36. _Chloridops kona_ Hawaii.
+
+ CORVIDÆ (Crows).
+
+ 37. _Corvus hawaiiensis_ Hawaii.
+
+Many of the birds recently described are representative forms found in the
+several islands of the group.
+
+Taking the above in the order here given, we have, first, two peculiar
+genera of true flycatchers, a family confined to the Old World, but
+extending over the Pacific as far as the Marquesas Islands. Next we have
+two peculiar genera (with four species) of honeysuckers, a family confined
+to the Australian region, and also ranging over all the Pacific Islands to
+the Marquesas. We now come to the most important group of birds in the
+Sandwich Islands, comprising seven or eight peculiar genera, and twenty-two
+species which are believed to form a peculiar family allied to the Oriental
+flower-peckers (Diceidæ), and perhaps remotely to the American greenlets
+(Vireonidæ), or {316} tanagers (Tanagridæ). They possess singularly varied
+beaks, some having this organ much thickened like those of finches, to
+which family some of them have been supposed to belong. In any case they
+form a most peculiar group, and cannot be associated with any other known
+birds. The last species, and the only one not belonging to a peculiar
+genus, is the Hawaiian crow, belonging to the almost universally
+distributed genus Corvus.
+
+On the whole, the affinities of these birds are, as might be expected,
+chiefly with Australia and the Pacific Islands; but they exhibit in the
+buzzard, one of the owls, and perhaps in some of the Drepanididæ, slight
+indications of very rare or very remote communication with America. The
+amount of speciality is, however, wonderful, far exceeding that of any
+other islands; the only approach to it being made by New Zealand and
+Madagascar, which have a much more varied bird fauna and a smaller
+_proportionate_ number of peculiar genera. The Galapagos, among the true
+oceanic islands, while presenting many peculiarities have only four out of
+the ten genera of Passeres peculiar. These facts undoubtedly indicate an
+immense antiquity for this group of islands, or the vicinity of some very
+ancient land (now submerged), from which some portion of their peculiar
+fauna might be derived. For further details as to the affinities and
+geographical distribution of the genera and species, the reader must
+consult Mr. Scott Wilson's work _The Birds of the Sandwich Islands_,
+already alluded to.
+
+_Reptiles._--The only other vertebrate animals are two lizards. One of
+these is a very widespread species, _Ablepharus poecilopleurus_, ranging
+from the Pacific Islands to West Africa. The other is said to form a
+peculiar genus of geckoes, but both its locality and affinities appear to
+be somewhat doubtful.
+
+_Land-shells._--The only other group of animals which has been carefully
+studied, and which presents features of especial interest, are the
+land-shells. These are very numerous, about thirty genera, and between
+three and four hundred species having been described; and it is remarkable
+that this single group contains as many species of {317} land-shells as all
+the other Polynesian Islands from the Pelew Islands and Samoa to the
+Marquesas. All the species are peculiar, and about three-fourths of the
+whole belong to peculiar genera, fourteen of which constitute the subfamily
+Achatinellinæ, entirely confined to this group of islands and constituting
+its most distinguishing feature. Thirteen genera (comprising sixty-four
+species) are found also in the other Polynesian Islands, but three genera
+of Auriculidæ (Plecotrema, Pedipes, and Blauneria) are not found in the
+Pacific, but inhabit--the former genus Australia, China, Bourbon, and Cuba,
+the two latter the West Indian Islands. Another remarkable peculiarity of
+these islands is the small number of Operculata, which are represented by
+only one genus and five species, while the other Pacific Islands have
+twenty genera and 115 species, or more than half the number of the
+Inoperculata. This difference is so remarkable that it is worth stating in
+a comparative form:--
+
+ Inoperculata. Operculata. Auriculidæ.
+ Sandwich Islands 332 5 9
+ Rest of Pacific Islands 200 115 16
+
+When we remember that in the West Indian Islands the Operculata abound in a
+greater proportion than even in the Pacific Islands generally, we are led
+to the conclusion that limestone, which is plentiful in both these areas,
+is especially favourable to them, while the purely volcanic rocks are
+especially unfavourable. The other peculiarities of the Sandwich Islands,
+however, such as the enormous preponderance of the strictly endemic
+Achatinellinæ, and the presence of genera which occur elsewhere only beyond
+the Pacific area in various parts of the great continents, undoubtedly
+point to a very remote origin, at a time when the distribution of many of
+the groups of mollusca was very different from that which now prevails.
+
+A very interesting feature of the Sandwich group is the extent to which the
+species and even the genera are confined to separate islands. Thus the
+genera Carelia and Catinella with eight species are peculiar to the island
+of Kaui; Bulimella, Apex, Frickella, and Blauneria, to Oahu; Perdicella to
+Maui; and Eburnella to Lanai. {318} The Rev. John T. Gulick, who has made a
+special study of the Achatinellinæ, informs us that the average range of
+the species in this sub-family is five or six miles, while some are
+restricted to but one or two square miles, and only very few have the range
+of a whole island. Each valley, and often each side of a valley, and
+sometimes even every ridge and peak possesses its peculiar species.[73] The
+island of Oahu, in which the capital is situated, has furnished about half
+the species already known. This is partly due to its being more
+forest-clad, but also, no doubt, in part to its being better explored, so
+that notwithstanding the exceptional riches of the group, we have no reason
+to suppose that there are not many more species to be found in the less
+explored islands. Mr. Gulick tells us that the forest region that covers
+one of the mountain ranges of Oahu is about forty miles in length, and five
+or six miles in width, yet this small territory furnishes about 175 species
+of Achatinellidæ, represented by 700 or 800 varieties. The most important
+peculiar genus, not belonging to the Achatinella group, is Carelia, with
+six species and several named varieties, all peculiar to Kaui, the most
+westerly of the large islands. This would seem to show that the small
+islets stretching westward, and situated on an extensive bank with less
+than a thousand fathoms of water over it, may indicate the position of a
+large submerged island whence some portion of the Sandwich Island fauna was
+derived.
+
+_Insects._--Owing to the researches of the Rev. T. Blackburn we have now a
+fair knowledge of the Coleopterous fauna of these islands. Unfortunately
+some of the most productive islands in plants--Kaui and Maui--were very
+little explored, but during a residence of six years the equally rich Oahu
+was well worked, and the general character of the beetle fauna must
+therefore be considered to be pretty accurately determined. Out of 428
+species collected, many being obviously recent introductions, no {319} less
+than 352 species and 99 of the genera appear to be quite peculiar to the
+archipelago. Sixty of these species are Carabidæ, forty-two are
+Staphylinidæ, forty are Nitidulidæ, twenty are Ptinidæ, twenty are Ciodidæ,
+thirty are Aglycyderidæ, forty-five are Curculionidæ, and fourteen are
+Cerambycidæ, the remainder being distributed among twenty-two other
+families. Many important families, such as Cicindelidæ, Scaraboeidæ,
+Buprestidæ, and the whole of the enormous series of the Phytophaga are
+either entirely absent or are only represented by a few introduced species.
+In the eight families enumerated above most of the species belong to
+peculiar genera which usually contain numerous distinct species; and we may
+therefore consider these to represent the descendants of the most ancient
+immigrants into the islands.
+
+Two important characteristics of the Coleopterous fauna are, the small size
+of the species, and the great scarcity of individuals. Dr. Sharp, who has
+described many of them,[74] says they are "mostly small or very minute
+insects," and that "there are few--probably it would be correct to say
+absolutely none--that would strike an ordinary observer as being
+beautiful." Mr. Blackburn says that it was not an uncommon thing for him to
+pass a morning on the mountains and to return home with perhaps two or
+three specimens, having seen literally nothing else except the few species
+that are generally abundant. He states that he "has frequently spent an
+hour sweeping flower-covered herbage, or beating branches of trees over an
+inverted white umbrella without seeing the sign of a beetle of any kind."
+To those who have collected in any tropical or even temperate country on or
+near a continent, this poverty of insect life must seem almost incredible;
+and it affords us a striking proof of how erroneous are those now almost
+obsolete views which imputed the abundance, variety, size, and colour of
+insects to the warmth and sunlight and luxuriant vegetation of the tropics.
+The facts become quite intelligible, however, if we consider that only
+{320} minute insects of certain groups could ever reach the islands by
+natural means, and that these, already highly specialised for certain
+defined modes of life, could only develop slowly into slightly modified
+forms of the original types. Some of the groups, however, are considered by
+Dr. Sharp to be very ancient generalised forms, especially the peculiar
+family Aglycyderidæ, which he looks upon as being "absolutely the most
+primitive of all the known forms of Coleoptera, it being a synthetic form
+linking the isolated Rhynchophagous series of families with the Clavicorn
+series. About thirty species are known in the Hawaiian Islands, and they
+exhibit much difference _inter se_." A few remarks on each of the more
+important of the families will serve to indicate their probable mode and
+period of introduction into the islands.
+
+The Carabidæ consist chiefly of seven peculiar genera of Anchomenini
+comprising fifty-one species, and several endemic species of Bembidiinæ.
+They are highly peculiar and are all of small size, and may have originally
+reached the islands in the crevices of the drift wood from N.W. America
+which is still thrown on their shores, or, more rarely, by means of a
+similar drift from the N.-Western islands of the Pacific.[75] It is
+interesting to note that peculiar species of the same groups of Carabidæ
+are found in the Azores, Canaries, and St. Helena, indicating that they
+possess some special facilities for transmission across wide oceans and for
+establishing themselves upon oceanic islands. The Staphylinidæ present many
+peculiar species of known genera. Being still more minute and usually more
+ubiquitous than the Carabidæ, there is no difficulty in accounting for
+their presence in the islands by the same means of dispersal. The
+Nitidulidæ, Ptinidæ, and Ciodidæ being very small and of varied habits,
+either the perfect insects, their eggs or larvæ, may have been introduced
+either by water or wind carriage, or through the agency of birds. The
+Curculionidæ, being wood bark or nut borers, would have considerable
+facilities for transmission by floating timber, fruits, or nuts; and the
+eggs or larvæ of the {321} peculiar Cerambycidæ must have been introduced
+by the same means. The absence of so many important and cosmopolitan groups
+whose size or constitution render them incapable of being thus transmitted
+over the sea, as well as of many which seem equally well adapted as those
+which are found in the islands, indicate how rare have been the conditions
+for successful immigration; and this is still further emphasized by the
+extreme specialisation of the fauna, indicating that there has been no
+repeated immigration of the same species which would tend, as in the case
+of Bermuda, to preserve the originally introduced forms unchanged by the
+effects of repeated intercrossing.
+
+_Vegetation of the Sandwich Islands._--The flora of these islands is in
+many respects so peculiar and remarkable, and so well supplements the
+information derived from its interesting but scanty fauna, that a brief
+account of its more striking features will not be out of place; and we
+fortunately have a pretty full knowledge of it, owing to the researches of
+the German botanist Dr. W. Hildebrand.[76]
+
+Considering their extreme isolation, their uniform volcanic soil, and the
+large proportion of the chief island which consists of barren lava-fields,
+the flora of the Sandwich Islands is extremely rich, consisting, so far as
+at present known, of 844 species of flowering plants and 155 ferns. This is
+considerably richer than the Azores (439 Phanerogams and 39 ferns), which
+though less extensive are perhaps better known, or than the Galapagos (332
+Phanerogams), which are more strictly comparable, being equally volcanic,
+while their somewhat smaller area may perhaps be compensated by their
+proximity to the American continent. Even New Zealand with more than twenty
+times the area of the Sandwich group, whose soil and climate are much more
+varied and whose botany has been thoroughly explored, has not a very much
+larger number of flowering plants (935 species), while in ferns it is
+barely equal.
+
+{322}
+
+The following list gives the number of indigenous species in each natural
+order.
+
+_Number of Species in each Natural Order in the Hawaiian Flora, excluding
+the introduced Plants._
+
+ DICOTYLEDONS. 48. Gentianaceæ (Erythræa) 1
+ 49. Loganiaceæ 7
+ 1. Ranunculaceæ 2 50. Apocynaceæ 4
+ 2. Menispermaceæ 4 51. Hydrophyllaceæ (Nama ...
+ 3. Papaveraceæ 1 allies Andes) 1
+ 4. Cruciferæ 3 52. Oleaceæ 1
+ 5. Capparidaceæ 2 53. Solanaceæ 12
+ 6. Violaceæ 8 54. Convolvulaceæ 14
+ 7. Bixaceæ 2 55. Boraginaceæ 3
+ 8. Pittosporaceæ 10 56. Scrophulariaceæ 2
+ 9. Caryophyllaceæ 23 57. Gesneriaceæ 24
+ 10. Portulaceæ 3 58. Myoporaceæ 1
+ 11. Guttiferæ 1 59. Verbenaceæ 1
+ 12. Ternstræmiaceæ 1 60. Labiatæ 39
+ 13. Malvaceæ 14 61. Plantaginaceæ 2
+ 14. Sterculiaceæ 2 62. Nyctaginaceæ 5
+ 15. Tiliaceæ 1 63. Amarantaceæ 9
+ 16. Geraniaceæ 6 64. Phytolaccaceæ 1
+ 17. Zygophyllaceæ 1 65. Polygonaceæ 3
+ 18. Oxalidaceæ 1 66. Chenopodiaceæ 2
+ 19. Rutaceæ 30 67. Lauraceæ 2
+ 20. Ilicineæ 1 68. Thymelæaceæ 7
+ 21. Celastraceæ 1 69. Santalaceæ 5
+ 22. Rhamnaceæ 7 70. Loranthaceæ 1
+ 23. Sapindaceæ 6 71. Euphorbiaceæ 12
+ 24. Anacardiaceæ 1 72. Urticaceæ 15
+ 25. Leguminosæ 21 73. Piperaceæ 20
+ 26. Rosaceæ 6
+ 27. Saxifragaceæ (trees) 2 MONOCOTYLEDONS.
+ 28. Droseraceæ 1
+ 29. Halorageæ 1 74. Orchidaceæ 3
+ 30. Myrtaceæ 6 75. Scitaminaceæ 4
+ 31. Lythraceæ 1 76. Iridaceæ 1
+ 32. Onagraceæ 1 77. Taccaceæ 1
+ 33. Cucurbitaceæ 8 78. Dioscoreaceæ 2
+ 34. Ficoideæ 1 79. Liliaceæ 7
+ 35. Begoniaceæ 1 80. Commelinaceæ 1
+ 36. Umbelliferæ 5 81. Flagellariaceæ 1
+ 37. Araliaceæ 12 82. Juncaceæ 1
+ 38. Rubiaceæ 49 83. Palmaceæ 3
+ 39. Compositæ 70 84. Pandanaceæ 2
+ 40. Lobeliaceæ 58 85. Araceæ 2
+ 41. Goodeniaceæ 8 86. Naiadaceæ 4
+ 42. Vaccinaceæ 2 87. Cyperaceæ 47
+ 43. Epacridaceæ 2 88. Graminaceæ 57
+ 44. Sapotaceæ 3
+ 45. Myrsinaceæ 5 VASCULAR CRYPTOGAMS.
+ 46. Primulaceæ (Lysimachia)
+ shrubs 6 Ferns 136
+ 47. Plumbaginaceæ 1 Lycopodiaceæ 17
+ Rhizocarpeæ 2
+
+{323}
+
+_Peculiar Features of the Flora._--This rich insular flora is wonderfully
+peculiar, for if we deduct 115 species, which are believed to have been
+introduced by man, there remain 705 species of flowering plants of which
+574, or more than four-fifths, are quite peculiar to the islands. There are
+no less than 38 peculiar genera out of a total of 265 and these 38 genera
+comprise 254 species, so that the most isolated forms are those which most
+abound and thus give a special character to the flora. Besides these
+peculiar types, several genera of wide range are here represented by highly
+peculiar species. Such are the Hawaiian species of Lobelia which are woody
+shrubs either creeping or six feet high, while a species of one of the
+peculiar genera of Lobeliaceæ is a tree reaching a height of forty feet.
+Shrubby geraniums grow twelve or fifteen feet high, and some vacciniums
+grow as epiphytes on the trunks of trees. Violets and plantains also form
+tall shrubby plants, and there are many strange arborescent compositæ, as
+in other oceanic islands.
+
+The affinities of the flora generally are very wide. Although there are
+many Polynesian groups, yet Australian, New Zealand, and American forms are
+equally represented. Dr. Pickering notes the total absence of a large
+number of families found in Southern Polynesia, such as Dilleniceæa,
+Anonaceæ, Olacaceæ, Aurantiaceæ, Guttiferæ, Malpighiaceæ, Meliaceæ,
+Combretaceæ, Rhizophoraceæ, Melastomaceæ, Passifloraceæ, Cunoniaceæ,
+Jasminaceæ, Acanthaceæ, Myristicaceæ, and Casuaraceæ, as well as the genera
+Clerodendron, Ficus, and epidendric orchids. Australian affinities are
+shown by the genera Exocarpus, Cyathodes, Melicope, Pittosporum, and by a
+phyllodinous Acacia. New Zealand is represented by Ascarina, Coprosma,
+Acæna, and several Cyperaceæ; while America is represented by the genera
+Nama, Gunnera, Phyllostegia, Sisyrinchium, and by a red-flowered Rubus and
+a yellow-flowered Sanicula allied to Oregon species.
+
+There is no true alpine flora on the higher summits, but several of the
+temperate forms extend to a great elevation. Thus Mr. Pickering records
+Vaccinium, Ranunculus, Silene, Gnaphalium and Geranium, as occurring above
+ten {324} thousand feet elevation; while Viola, Drosera, Acæna, Lobelia,
+Edwardsia, Dodonæa, Lycopodium, and many Compositæ, range above six
+thousand feet. Vaccinium and Silene are very interesting, as they are
+almost peculiar to the North Temperate zone; while many plants allied to
+Antarctic species are found in the bogs of the high plateaux.
+
+The proportionate abundance of the different families in this interesting
+flora is as follows:--
+
+ 1. Compositæ 70 species, 12. Urticaceæ 15 species,
+ 2. Lobeliaceæ 58 ,, 13. Malvaceæ 14 ,,
+ 3. Graminaceæ 57 ,, 14. Convolvulaceæ 14 ,,
+ 4. Rubiaceæ 49 ,, 15. Araliaceæ 12 ,,
+ 5. Cyperaceæ 47 ,, 16. Solanaceæ 12 ,,
+ 6. Labiatæ 39 ,, 17. Euphorbiaceæ 12 ,,
+ 7. Rutaceæ 30 ,, 18. Pittosporaceæ 10 ,,
+ 8. Gesneriaceæ 24 ,, 19. Amarantaceæ 9 ,,
+ 9. Caryophyllaceæ 23 ,, 20. Violaceæ 8 ,,
+ 10. Leguminosæ 21 ,, 21. Goodeniaceæ 8 ,,
+ 11. Piperaceæ 20 ,,
+
+Nine other orders, Geraniaceæ, Rhamnaceæ, Rosaceæ, Myrtaceæ, Primulaceæ,
+Loganiaceæ, Liliaceæ, Thymelaceæ, and Cucurbitaceæ, have six or seven
+species each; and among the more important orders which have less than five
+species each are Ranunculaceæ, Cruciferæ, Vaccinacæ, Apocynaceæ,
+Boraginaceæ, Scrophulariaceæ, Polygonaceæ, Orchidaceæ, and Juncaceæ. The
+most remarkable feature here is the great abundance of Lobeliaceæ, a
+character of the flora which is probably unique; while the superiority of
+Labiatæ to Leguminosæ and the scarcity of Rosaceæ and Orchidaceæ are also
+very unusual. Composites, as in most temperate floras, stand at the head of
+the list, and it will be interesting to note the affinities which they
+indicate. Omitting eleven species which are cosmopolitan, and have no doubt
+entered with civilised man, there remain nineteen genera and seventy
+species of Compositæ in the islands. Sixty-one of the species are peculiar,
+as are eight of the genera; while the genus Lipochæta with eleven species
+is only known elsewhere in the Galapagos, where a single species occurs. We
+may therefore consider that nine out of the nineteen genera of Hawaiian
+{325} Compositæ are really confined to the Archipelago. The relations of
+the peculiar genera and species are indicated in the following table.[77]
+
+_Affinities of Hawaiian Composites._
+
+ No. of
+ Peculiar Genera. Species. External Affinities of the Genus.
+
+ Remya 2 Very peculiar. Allied to the North American
+ genus Grindelia.
+ Tetramolobium 7 South Temperate America and Australia.
+ Lipochæta 11 Allied to American genera.
+ Campylothæca 12 With Tropical American species of Bidens and
+ Coreopsis.
+ Argyroxiphium 2 With the Mexican Madieæ.
+ Wilkesia 2 Same affinities.
+ Dubantia 6 With the Mexican Raillardella.
+ Raillardia 12 Same affinities.
+ Hesperomannia 2 Allied to Stifftia and Wunderlichia of Brazil.
+
+ Peculiar Species.
+
+ Lagenophora 1 Australia, New Zealand, Antarctic America,
+ Fiji Islands.
+ Senecio 2 Universally distributed.
+ Artemisia 2 North Temperate Regions.
+
+The great preponderance of American relations in the Compositæ, as above
+indicated, is very interesting and suggestive, since the Compositæ of
+Tahiti and the other Pacific Islands are allied to Malaysian types. It is
+here that we meet with some of the most isolated and remarkable forms,
+implying great antiquity; and when we consider the enormous extent and
+world-wide distribution of this order (comprising about ten thousand
+species), its distinctness from all others, the great specialisation of its
+flowers to attract insects, and of its seeds for dispersal by wind and
+other means, we can hardly doubt that its origin dates back to a very
+remote epoch. We may therefore look upon the Compositæ as representing the
+most ancient portion of the existing flora of the Sandwich Islands,
+carrying us back to a very remote period when the facilities for
+communication with America were greater than they are now. This may be
+indicated by the two deep submarine banks in the North Pacific, between the
+Sandwich Islands and San Francisco, which, from an ocean floor {326} nearly
+3,000 fathoms deep, rise up to within a few hundred fathoms of the surface,
+and seem to indicate the subsidence of two islands, each about as large as
+Hawaii. The plants of North Temperate affinity may be nearly as old, but
+these may have been derived from Northern Asia by way of Japan and the
+extensive line of shoals which run north-westward from the Sandwich
+Islands, as shown on our map. Those which exhibit Polynesian or Australian
+affinities, consisting for the most part of less highly modified species,
+usually of the same genera, may have had their origin at a later, though
+still somewhat remote period, when large islands, indicated by the
+extensive shoals to the south and south-west, offered facilities for the
+transmission of plants from the tropical portions of the Pacific Ocean.
+
+It is in the smaller and most woody islands in the westerly portion of the
+group, especially in Kauai and Oahu, that the greatest number and variety
+of plants are found and the largest proportion of peculiar species and
+genera. These are believed to form the oldest portion of the group, the
+volcanic activity having ceased and allowed a luxuriant vegetation more
+completely to cover the islands, while in the larger and much newer islands
+of Hawaii and Maui the surface is more barren and the vegetation
+comparatively monotonous. Thus while twelve of the arborescent Lobeliaceæ
+have been found on Hawaii no less than seventeen occur on the much smaller
+Oahu, which has even a genus of these plants confined to it.
+
+It is interesting to note that while the non-peculiar genera of flowering
+plants have little more than two species to a genus, the endemic genera
+average six and three-quarter species to a genus. These may be considered
+to represent the earliest immigrants which became firmly established in the
+comparatively unoccupied islands, and have gradually become modified into
+such complete harmony with their new conditions that they have developed
+into many diverging forms adapting them to different _habitats_. The
+following is a list of the peculiar genera with the number of species in
+each. {327}
+
+_Peculiar Hawaiian Genera of Flowering Plants._
+
+ Genus. No. of Species. Natural Order.
+
+ 1. Isodendrion 3 Violaceæ.
+ 2. Schiedea (seeds rugose or muricate) 17 Caryophyllaceæ.
+ 3. Alsinidendron 1 ,,
+ 4. Pelea 20 Rutaceæ.
+ 5. Platydesma 4 ,,
+ 6. Mahoe 1 Sapindaceæ.
+ 7. Broussaisia 2 Saxifragaceæ.
+ 8. Hildebrandia 1 Begoniaceæ.
+ 9. Cheirodendron (fleshy fruit) 2 Araliaceæ.
+ 10. Pterotropia (succulent) 3 ,,
+ 11. Triplasandra (drupe) 4 ,,
+ 12. Kadua (small, flat, winged seeds) 16 Rubiaceæ.
+ 13. Gouldia (berry) 5 ,,
+ 14. Bobea (drupe) 5 ,,
+ 15. Straussia (drupe) 5 ,,
+ 16. Remya 2 Compositæ.
+ 17. Tetramolobium 7 ,,
+ 18. Lipochæta 11 ,,
+ 19. Campylotheca 12 ,,
+ 20. Argyroxiphium 2 ,,
+ 21. Wilkesia 2 ,,
+ 22. Dubautia 6 ,,
+ 23. Raillardia 12 ,,
+ 24. Hesperomannia 2 ,,
+ 25. Brighamia 1 Lobeliaceæ.
+ 26. Clermontia (berry) 11 ,,
+ 27. Rollandia 6 ,,
+ 28. Delissea 7 ,,
+ 29. Cyanea 28 ,,
+ 30. Labordea 9 Loganiaceæ.
+ 31. Nothocestrum 4 Solanaceæ.
+ 32. Haplostachys (nucules dry) 3 Labiatæ.
+ 33. Phyllostegia (nucules fleshy) 16 ,,
+ 34. Stenogyne (nucules fleshy) 16 ,,
+ 35. Nototrichium 3 Amarantaceæ.
+ 36. Charpentiera 2 ,,
+ 37. Touchardia 1 Urticaceæ.
+ 38. Neraudia 2 ,,
+ ----
+ Total 254 species.
+
+The great preponderance of the two orders Compositæ and Lobeliaceæ are what
+first strike us in this list. In the former case the facilities for
+wind-dispersal afforded by the structure of so many of the seeds render it
+comparatively easy to account for their having reached the islands at an
+early period. The Lobelias, judging from Hildebrand's descriptions, may
+have been transported in several {328} different ways. Most of the endemic
+genera are berry-bearers and thus offer the means of dispersal by
+fruit-eating birds. The endemic species of the genus Lobelia have sometimes
+very minute seeds, which might be carried long distances by wind, while
+other species, especially Lobelia gaudichaudii, have a "hard, almost woody
+capsule which opens late," apparently well adapted for floating long
+distances. Afterwards "the calycine covering withers away, leaving a
+fenestrate woody network" enclosing the capsule, and the seeds themselves
+are "compressed, reniform, or orbicular, and margined," and thus of a form
+well adapted to be carried to great heights and distances by gales or
+hurricanes.
+
+In the other orders which present several endemic genera indications of the
+mode of transit to the islands are afforded us. The Araliaceæ are said to
+have fleshy fruits or drupes more or less succulent. The Rubiaceæ have
+usually berries or drupes, while one genus, Kadua, has "small, flat, winged
+seeds." The two largest genera of the Labiatæ are said to have "fleshy
+nucules," which would no doubt be swallowed by birds.[78]
+
+_Antiquity of the Hawaiian Fauna and Flora._--The great antiquity implied
+by the peculiarities of the fauna and flora, no less than by the
+geographical conditions and surroundings, of this group, will enable us to
+account for another peculiarity of its flora--the absence of so many
+families found in other Pacific Islands. For the earliest immigrants would
+soon occupy much of the surface, and become specially modified in
+accordance with the conditions of the locality, and these would serve as a
+barrier against the intrusion of many forms which at a later {329} period
+spread over Polynesia. The extreme remoteness of the islands, and the
+probability that they have always been more isolated than those of the
+Central Pacific, would also necessarily result in an imperfect and
+fragmentary representation of the flora of surrounding lands.
+
+_Concluding Observations on the Fauna and Flora of the Sandwich
+Islands._--The indications thus afforded by a study of the flora seem to
+accord well with what we know of the fauna of the islands. Plants having so
+much greater facilities for dispersal than animals, and also having greater
+specific longevity and greater powers of endurance under adverse
+conditions, exhibit in a considerable degree the influence of the primitive
+state of the islands and their surroundings; while members of the animal
+world, passing across the sea with greater difficulty and subject to
+extermination by a variety of adverse conditions, retain much more of the
+impress of a recent state of things, with perhaps here and there an
+indication of that ancient approach to America so clearly shown in the
+Compositæ and some other portions of the flora.
+
+GENERAL REMARKS ON OCEANIC ISLANDS.
+
+We have now reviewed the main features presented by the assemblages of
+organic forms which characterise the more important and best known of the
+Oceanic Islands. They all agree in the total absence of indigenous mammalia
+and amphibia, while their reptiles, when they possess any, do not exhibit
+indications of extreme isolation and antiquity. Their birds and insects
+present just that amount of specialisation and diversity from continental
+forms which may be well explained by the known means of dispersal acting
+through long periods; their land shells indicate greater isolation, owing
+to their admittedly less effective means of conveyance across the ocean;
+while their plants show most clearly the effects of those changes of
+conditions which we have reason to believe have occurred during the
+Tertiary epoch, and preserve to us in highly specialised and archaic forms
+some record of the primeval immigration by which the islands were
+originally {330} clothed with vegetation. But in every case the series of
+forms of life in these islands is scanty and imperfect as compared with far
+less favourable continental areas, and no one of them presents such an
+assemblage of animals or plants as we always find in an island which we
+know has once formed part of a continent.
+
+It is still more important to note that none of these oceanic archipelagoes
+present us with a single type which we may suppose to have been preserved
+from Mesozoic times; and this fact, taken in connection with the volcanic
+or coralline origin of all of them, powerfully enforces the conclusion at
+which we have arrived in the earlier portion of this volume, that during
+the whole period of geologic time as indicated by the fossiliferous rocks,
+our continents and oceans have, speaking broadly, been permanent features
+of our earth's surface. For had it been otherwise--had sea and land changed
+place repeatedly as was once supposed--had our deepest oceans been the seat
+of great continents while the site of our present continents was occupied
+by an oceanic abyss--is it possible to imagine that no fragments of such
+continents would remain in the present oceans, bringing down to us some of
+their ancient forms of life preserved with but little change? The
+correlative facts, that the islands of our great oceans are all volcanic
+(or coralline built probably upon degraded volcanic islands or extinct
+submarine volcanoes), and that their productions are all more or less
+clearly related to the existing inhabitants of the nearest continents, are
+hardly consistent with any other theory than the permanence of our oceanic
+and continental areas.
+
+We may here refer to the one apparent exception, which, however, lends
+additional force to the argument. New Zealand is sometimes classed as an
+oceanic island, but it is not so really; and we shall discuss its
+peculiarities and probable origin further on.
+
+ * * * * *
+
+
+{331}
+
+CHAPTER XVI
+
+CONTINENTAL ISLANDS OF RECENT ORIGIN: GREAT BRITAIN
+
+ Characteristic Features of Recent Continental Islands--Recent Physical
+ Changes of the British Isles--Proofs of Former Elevation--Submerged
+ Forests--Buried River Channels--Time of Last Union with the
+ Continent--Why Britain is poor in Species--Peculiar British
+ Birds--Freshwater Fishes--Cause of Great Speciality in Fishes--Peculiar
+ British Insects--Lepidoptera Confined to the British
+ Isles--Peculiarities of the Isle of Man--Lepidoptera--Coleoptera
+ confined to the British Isles--Trichoptera Peculiar to the British
+ Isles--Land and Freshwater Shells--Peculiarities of the British
+ Flora--Peculiarities of the Irish Flora--Peculiar British Mosses and
+ Hepaticæ--Concluding Remarks on the Peculiarities of the British Fauna
+ and Flora.
+
+We now proceed to examine those islands which are the very reverse of the
+"oceanic" class, being fragments of continents or of larger islands from
+which they have been separated, by subsidence of the intervening land at a
+period which, geologically, must be considered recent. Such islands are
+always still connected with their parent land by a shallow sea, usually
+indeed not exceeding a hundred fathoms deep; they always possess mammalia
+and reptiles either wholly or in large proportion identical with those of
+the mainland; while their entire flora and fauna is characterised either by
+the total absence or comparative scarcity of those endemic or peculiar
+species and genera which are so striking a feature of almost all oceanic
+islands. Such islands will, of course, differ from each {332} other in
+size, in antiquity, and in the richness of their respective faunas, as well
+as in their distance from the parent land and the facilities for
+intercommunication with it; and these diversities of conditions will
+manifest themselves in the greater or less amount of speciality of their
+animal productions.
+
+This speciality, when it exists, may have been brought about in two ways. A
+species or even a genus may on a continent have had a very limited area of
+distribution, and this area may be wholly or almost wholly contained in the
+separated portion or island, to which it will henceforth be peculiar. Even
+when the area occupied by a species is pretty equally divided at the time
+of separation between the island and the continent, it may happen that it
+will become extinct on the latter, while it may survive on the former,
+because the limited number of individuals after division may be unable to
+maintain themselves against the severer competition or more contrasted
+climate of the continent, while they may flourish, under the more
+favourable insular conditions. On the other hand, when a species continues
+to exist in both areas, it may on the island be subjected to some
+modifications by the altered conditions, and may thus come to present
+characters which differentiate it from its continental allies and
+constitute it a new species. We shall in the course of our survey meet with
+cases illustrative of both these processes.
+
+The best examples of recent continental islands are Great Britain and
+Ireland, Japan, Formosa, and the larger Malay Islands, especially Borneo,
+Java, and Celebes; and as each of these presents special features of
+interest, we will give a short outline of their zoology and past history in
+relation to that of the continents from which they have recently been
+separated, commencing with our own islands, to which the present chapter
+will be devoted.
+
+_Recent Physical Changes in the British Isles._--Great Britain is perhaps
+the most typical example of a large and recent continental island now to be
+found upon the globe. It is joined to the Continent by a shallow bank which
+extends from Denmark to the Bay of Biscay, the 100 fathom line from these
+extreme points receding from the {333} coasts so as to include the whole of
+the British Isles and about fifty miles beyond them to the westward. (_See_
+Map.)
+
+[Illustration: MAP SHOWING THE SHALLOW BANK CONNECTING THE BRITISH ISLES
+WITH THE CONTINENT.]
+
+ The light tint indicates a depth of less than 100 fathoms.
+ The figures show the depth in fathoms.
+ The narrow channel between Norway and Denmark is 2,580 feet deep.
+
+Beyond this line the sea deepens rapidly to the 500 and 1,000 fathom lines,
+the distance between 100 and 1,000 {334} fathoms being from twenty to fifty
+miles, except where there is a great outward curve to include the Porcupine
+Bank 170 miles west of Galway, and to the north-west of Caithness where a
+narrow ridge less than 500 fathoms below the surface joins the extensive
+bank under 300 fathoms, on which are situated the Faroe Islands and
+Iceland, and which stretches across to Greenland. In the North Channel
+between Ireland and Scotland, and in the Minch between the outer Hebrides
+and Skye, are a series of hollows in the sea-bottom from 100 to 150 fathoms
+deep. These correspond exactly to the points between the opposing highlands
+where the greatest accumulations of ice would necessarily occur during the
+glacial epoch, and they may well be termed submarine lakes, of exactly the
+same nature as those which occur in similar positions on land.
+
+_Proofs of Former Elevation--Submerged Forests._--What renders Britain
+particularly instructive as an example of a recent continental island is
+the amount of direct evidence that exists, of several distinct kinds,
+showing that the land has been sufficiently elevated (or the sea depressed)
+to unite it with the Continent,--and this at a very recent period. The
+first class of evidence is the existence, all round our coasts, of the
+remains of submarine forests often extending far below the present
+low-water mark. Such are the submerged forests near Torquay in Devonshire,
+and near Falmouth in Cornwall, both containing stumps of trees in their
+natural position rooted in the soil, with deposits of peat, branches, and
+nuts, and often with remains of insects and other land animals. These occur
+in very different conditions and situations, and some have been explained
+by changes in the height of the tide, or by pebble banks shutting out the
+tidal waters from estuaries; but there are numerous examples to which such
+hypotheses cannot apply, and which can only be explained by an actual
+subsidence of the land (or rise of the sea-level) since the trees grew.
+
+We cannot give a better idea of these forests than by quoting the following
+account by Mr. Pengelly of a visit to one which had been exposed by a
+violent storm on the coast of Devonshire, at Blackpool near Dartmouth:--
+{335}
+
+"We were so fortunate as to reach the beach at spring-tide low-water, and
+to find, admirably exposed, by far the finest example of a submerged forest
+which I have ever seen. It occupied a rectangular area, extending from the
+small river or stream at the western end of the inlet, about one furlong
+eastward; and from the low-water line thirty yards up the strand. The lower
+or seaward portion of the forest area, occupying about two-thirds of its
+entire breadth, consisted of a brownish drab-coloured clay, which was
+crowded with vegetable _débris_, such as small twigs, leaves, and nuts.
+There were also numerous prostrate trunks and branches of trees, lying
+partly imbedded in the clay, without anything like a prevalent direction.
+The trunks varied from six inches to upwards of two feet in diameter. Much
+of the wood was found to have a reddish or bright pink hue, when fresh
+surfaces were exposed. Some of it, as well as many of the twigs, had almost
+become a sort of ligneous pulp, while other examples were firm, and gave a
+sharp crackling sound on being broken. Several large stumps projected above
+the clay in a vertical direction, and sent roots and rootlets into the soil
+in all directions and to considerable distances. It was obvious that the
+movement by which the submergence was effected had been so uniform as not
+to destroy the approximate horizontality of the old forest ground. One fine
+example was noted of a large prostrate trunk having its roots still
+attached, some of them sticking up above the clay, while others were buried
+in it. Hazelnuts were extremely abundant--some entire, others broken, and
+some obviously gnawed.... It has been stated that the forest area reached
+the spring-tide low-water line; hence as the greatest tidal range on this
+coast amounts to eighteen feet, we are warranted in inferring that the
+subsidence amounted to eighteen feet as a minimum, even if we suppose that
+some of the trees grew in a soil the surface of which was not above the
+level of high water. There is satisfactory evidence that in Torbay it was
+not less than forty feet, and that in Falmouth Harbour it amounted to at
+least sixty-seven feet."[79]
+
+{336}
+
+On the coast of the Bristol Channel similar deposits occur, as well as
+along much of the coast of Wales and in Holyhead Harbour. It is believed by
+geologists that the whole Bristol Channel was, at a comparatively recent
+period, an extensive plain, through which flowed the River Severn; for in
+addition to the evidence of submerged forests there are on the coast of
+Glamorganshire numerous caves and fissures in the face of high sea cliffs,
+in one of which no less than a thousand antlers of the reindeer were found,
+the remains of animals which had been devoured there by bears and hyænas;
+facts which can only be explained by the existence of some extent of dry
+land stretching seaward from the present cliffs, but since submerged and
+washed away. This plain may have continued down to very recent times, since
+the whole of the Bristol Channel to beyond Lundy Island is under
+twenty-five fathoms deep. In the east of England we have a similar
+forest-bed at Cromer in Norfolk; and in the north of Holland an old land
+surface has been found fifty-six feet below high-water mark.
+
+_Buried River Channels._--Still more remarkable are the buried river
+channels which have been traced on many parts of our coasts. In order to
+facilitate the study of the glacial deposits of Scotland, Dr. James Croll
+obtained the details of about 250 bores put down in all parts of the mining
+districts of Scotland for the purpose of discovering minerals.[80] These
+revealed the interesting fact that there are ancient valleys and river
+channels at depths of from 100 to 260 feet below the present sea-level.
+These old rivers sometimes run in quite different directions from the
+present lines of drainage, connecting what are now distinct valleys; and
+they are so completely filled up and hidden by boulder clay, drift, and
+sands, that there is no indication of their presence on the surface, which
+often consists of mounds or low hills more than 100 feet high. One of these
+old valleys connects the Clyde near Dumbarton with the Forth at
+Grangemouth, and appears to have contained two streams flowing in opposite
+directions from a watershed about midway at Kilsith. At {337} Grangemouth
+the old channel is 260 feet below the sea-level. The watershed at Kilsith
+is now 160 feet above the sea, the old valley bottom being 120 feet deep or
+forty feet above the sea. In some places the old valley was a ravine with
+precipitous rocky walls, which have been found in mining excavations. Sir
+A. Geikie, who has himself discovered many similar buried valleys, is of
+opinion that "they unquestionably belong to the period of the boulder
+clay."
+
+We have here a clear proof that, when these rivers were formed, the land
+must have stood in relation to the sea _at least_ 260 feet higher than it
+does now, and probably much more; and this is sufficient to join England to
+the continent. Supporting this evidence, we have freshwater or littoral
+shells found at great depths off our coasts. Mr. Godwin Austen records the
+dredging up of a freshwater shell (_Unio pictorum_) off the mouth of the
+English Channel between the fifty fathom and 100 fathom lines, while in the
+same locality gravel banks with littoral shells now lie under sixty or
+seventy fathoms water.[81] More recently Mr. Gwyn Jeffreys has recorded the
+discovery of eight species of fossil arctic shells off the Shetland Isles
+in about ninety fathoms water, all being characteristic shallow water
+species, so that their association at this great depth is a distinct
+indication of considerable subsidence.[82]
+
+_Time of Last Union with the Continent._--The period when this last union
+with the continent took place was comparatively recent, as shown by the
+identity of the shells with living species, and the fact that the buried
+river channels are all covered with clays and gravels of the glacial
+period, of such a character as to indicate that most of them were deposited
+above the sea-level. From these and various other indications geologists
+are all agreed that the last continental period, as it is called, was
+subsequent to the greatest development of the ice, but probably before the
+cold epoch had wholly passed away. But if so recent, we should naturally
+expect our land still {338} to show an almost perfect community with the
+adjacent parts of the continent in its natural productions; and such is
+found to be the case. All the higher and more perfectly organised animals
+are, with but few exceptions, identical with those of France and Germany;
+while the few species still considered to be peculiar may be accounted for
+either by an original local distribution, by preservation here owing to
+favourable insular conditions, or by slight modifications having been
+caused by these conditions resulting in a local race, sub-species, or
+species.
+
+_Why Britain is Poor in Species._--The former union of our islands with the
+continent, is not, however, the only recent change they have undergone.
+There have been partial submergences to the depth of from one hundred to
+perhaps three hundred feet over a large part of our country; while during
+the period of maximum glaciation the whole area north of the Thames was
+buried in snow and ice. Even the south of England must have suffered the
+rigour of an almost arctic climate, since Mr. Clement Reid has shown that
+floating ice brought granite blocks from the Channel Islands to the coast
+of Sussex. Such conditions must have almost exterminated our preexisting
+fauna and flora, and it was only during the subsequent union of Britain
+with the continent that the bulk of existing animals and plants could have
+entered our islands. We know that just before and during the glacial period
+we possessed a fauna almost or quite identical with that of adjacent parts
+of the continent and equally rich in species. The glaciation and
+submergence destroyed much of this fauna; and the permanent change of
+climate on the passing away of the glacial conditions appears to have led
+to the extinction or migration of many species in the adjacent continental
+areas, where they were succeeded by the assemblage of animals now occupying
+Central Europe. When England became continental, these entered our country;
+but sufficient time does not seem to have elapsed for the migration to have
+been completed before subsidence again occurred, cutting off the further
+influx of purely terrestrial animals, and leaving us without the number of
+species which our favourable climate and varied surface entitle us to.
+{339}
+
+To this cause we must impute our comparative poverty in mammalia and
+reptiles--more marked in the latter than the former, owing to their lower
+vital activity and smaller powers of dispersal. Germany, for example,
+possesses nearly ninety species of land mammalia, and even Scandinavia
+about sixty, while Britain has only forty, and Ireland only twenty-two. The
+depth of the Irish Sea being somewhat greater than that of the German
+Ocean, the connecting land would there probably be of small extent and of
+less duration, thus offering an additional barrier to migration, whence has
+arisen the comparative zoological poverty of Ireland. This poverty attains
+its maximum in the reptiles, as shown by the following figures:--
+
+ Belgium has 22 species of reptiles and amphibia.
+ Britain ,, 13 ,, ,, ,,
+ Ireland ,, 4 ,, ,, ,,
+
+Where the power of flight existed, and thus the period of migration was
+prolonged, the difference is less marked; so that Ireland has seven bats to
+twelve in Britain, and about 110 as against 130 land-birds.
+
+Plants, which have considerable facilities for passing over the sea, are
+somewhat intermediate in proportionate numbers, there being about 970
+flowering plants and ferns in Ireland to 1,425 in Great Britain,--or almost
+exactly two-thirds, a proportion intermediate between that presented by the
+birds and the mammalia.
+
+_Peculiar British Birds._--Among our native mammalia, reptiles, and
+amphibia, it is the opinion of the best authorities that we possess neither
+a distinct species nor distinguishable variety. In birds, however, the case
+is different, since some of our species, in particular our coal-tit and
+long-tailed tit, present well-marked differences of colour as compared with
+continental specimens; and in Mr. Dresser's work on the _Birds of Europe_
+they are considered to be distinct species, while Professor Newton, in his
+new edition of Yarrell's _British Birds_, does not consider the difference
+to be sufficiently great or sufficiently constant to warrant this, and
+therefore classes {340} them as insular races of the continental species.
+We have, however, one undoubted case of a bird peculiar to the British
+Isles, in the red grouse (_Lagopus scoticus_), which abounds in Scotland,
+Ireland, the north of England, and Wales, and is very distinct from any
+continental species, although closely allied to the willow grouse of
+Scandinavia. This latter species resembles it considerably in its summer
+plumage, but becomes pure white in winter; whereas our species retains its
+dark plumage throughout the year, becoming even darker in winter than in
+summer. We have here therefore a most interesting example of an insular
+form in our own country; but it is difficult to determine how it
+originated. On the one hand, it may be an old continental species which
+during the glacial epoch found a refuge here when driven from its native
+haunts by the advancing ice; or, on the other hand, it may be a descendant
+of the Northern willow grouse, which has lost its power of turning white in
+winter owing to its long residence in the lowlands of an island where there
+is little permanent snow, and where assimilation in colour to the heather
+among which it lurks is at all times its best protection. In either case it
+is equally interesting, as the one large and handsome bird which is
+peculiar to our islands notwithstanding their recent separation from the
+continent.
+
+The following is a list of the birds now held to be peculiar to the British
+Isles:--
+
+ 1. Parus ater, _sub. sp._ BRITANNICUS Closely allied to _P. ater_ of
+ the continent; a local race or
+ sub-species.
+
+ 2. Acredula caudata, _sub. sp._ ROSEA Allied to _A. caudata_ of the
+ continent.
+
+ 3. LAGOPUS SCOTICUS Allied to _L. albus_ of
+ Scandinavia, a distinct species.
+
+_Freshwater Fishes._--Although the productions of fresh waters have
+generally, as Mr. Darwin has shown, a wide range, fishes appear to form an
+exception, many of them being extremely limited in distribution. Some are
+confined to particular river valleys or even to single rivers, others
+inhabit the lakes of a limited district only, while some are {341} confined
+to single lakes, often of small area, and these latter offer examples of
+the most restricted distribution of any organisms whatever. Cases of this
+kind are found in our own islands, and deserve our especial attention. It
+has long been known that some of our lakes possessed peculiar species of
+trout and charr, but how far these were unknown on the continent, and how
+many of those in different parts of our islands were really distinct, had
+not been ascertained till Dr. Günther, so well known for his extensive
+knowledge of the species of fishes, obtained numerous specimens from every
+part of the country, and by comparison with all known continental species
+determined their specific differences. The striking and unexpected result
+has thus been attained, that no less than fifteen well-marked species of
+freshwater fishes are altogether peculiar to the British Islands. The
+following is the list, with their English names and localities:--[83]
+
+_Freshwater Fishes peculiar to the British Isles._
+
+ _Latin Name._ | _English Name._ | _Locality._
+ | |
+ 1. SALMO BRACHYPOMA |Short-headed salmon|Firth of Forth, Tweed,
+ | |Ouse.
+ | |
+ 2. ,, GALLIVENSIS |Galway sea-trout |Galway, West Ireland.
+ | |
+ 3. ,, ORCADENSIS |Loch Stennis trout |Lakes of Orkney.
+ | |
+ 4. ,, FEROX |Great lake trout |Larger lakes of Scotland,
+ | |Ireland, the N. of England,
+ | |and Wales.
+ | |
+ 5. ,, STOMACHICUS |Gillaroo trout |Lakes of Ireland.
+ | |
+ 6. ,, NIGRIPINNIS |Black-finned trout |Mountain lochs of Wales
+ | |and Scotland.
+ | |
+ 7. ,, LEVENENSIS |Loch Leven Trout |Loch Leven, Loch Lomond,
+ | |Windermere.
+ | |
+ 8. ,, PERISII |Welsh charr |Llanberris lakes, N.
+ | |Wales.
+ | |
+ 9. ,, WILLUGHBII |Windermere charr |Lake Windermere and
+ | |others in N. of England,
+ | |and Lake Bruiach in
+ | |Scotland.
+ | |
+ 10. ,, KILLINENSIS |Lock Killin charr |Killin lake in
+ | |Inverness-shire.
+ | |
+ 11. ,, COLII |Cole's charr |Lough Eske and Lough
+ | |Dan, Ireland.
+ | |
+ 12. ,, GRAYI |Gray's charr |Lough Melvin, Leitrim,
+ | |N.W. Ireland.
+ | |
+ {342}
+ 13. COREGONUS CLUPEOIDES |The gwyniad, or |Loch Lomond, Ulleswater,
+ |schelly |Derwentwater,
+ | |Haweswater, and Bala
+ | |lake.
+ | |
+ 14. ,, VANDESIUS |The vendace |Loch Maben, Dumfriesshire.
+ | |
+ 15. ,, POLLAN |The pollan |Lough Neagh and Lough
+ | |Earne, N. of Ireland.
+
+These fifteen peculiar fishes differ from each other and from all British
+and continental species, not in colour only, but in such important
+structural characters as the number and size of the scales, form and size
+of the fins, and the form or proportions of the head, body, or tail. Some
+of them, like _S. killinensis_ and the Coregoni are in fact, as Dr. Günther
+assures me, just as good and distinct species as any other recognised
+species of fish. It may indeed be objected that, until all the small lakes
+of Scandinavia are explored, and their fishes compared with ours, we cannot
+be sure that we have any peculiar species. But this objection has very
+little weight if we consider how our own species vary from lake to lake and
+from island to island, so that the Orkney species is not found in Scotland,
+and only one of the peculiar British species extends to Ireland, which has
+no less than five species altogether peculiar to it. If the species of our
+own two islands are thus distinct, what reason have we for believing that
+they will be otherwise than distinct from those of Scandinavia? At all
+events, with the amount of evidence we already possess of the very
+restricted ranges of many of our species, we must certainly hold them to be
+peculiar till they have been proved to be otherwise.
+
+The great speciality of the Irish fishes is very interesting, because it is
+just what we should expect on the theory of evolution. In Ireland the two
+main causes of specific change--isolation and altered conditions--are each
+more powerful than in Britain. Whatever difficulty continental fishes may
+have in passing over to Britain, that difficulty will certainly be
+increased by the second sea passage to Ireland; and the latter country has
+been longer isolated, for the Irish Sea with its northern and southern
+channels is considerably deeper than the German Ocean and the {343} Eastern
+half of the English Channel, so that, when the last subsidence occurred,
+Ireland would have been an island for some length of time while England and
+Scotland still formed part of the continent. Again, whatever differences
+have been produced by the exceptional climate of our islands will have been
+greater in Ireland, where insular conditions are at a maximum, the
+abundance of moisture and the equability of temperature being far more
+pronounced than in any other part of Europe.
+
+Among the remarkable instances of limited distribution afforded by these
+fishes, we have the Loch Stennis trout confined to the little group of
+lakes in the mainland of Orkney, occupying altogether an area of about ten
+miles by three; the Welsh charr confined to the Llanberris lakes, about
+three miles in length; Gray's charr confined to Lough Melvin, about seven
+miles long; while the Loch Killin charr, known only from a small mountain
+lake in Inverness-shire, and the vendace, from the equally small lakes at
+Loch Maben in Scotland, are two examples of restricted distribution which
+can hardly be surpassed.
+
+_Cause of Great Speciality in Fishes._--The reason why fishes alone should
+exhibit such remarkable local modifications in lakes and islands is
+sufficiently obvious. It is due to the extreme rarity of their transmission
+from one lake to another. Just as we found to be the case in Oceanic
+Islands, where the means of transmission were ample hardly any modification
+of species occurred, while where these means were deficient and individuals
+once transported remained isolated during a long succession of ages, their
+forms and characters became so much changed as to bring about what we term
+distinct species or even distinct genera,--so these lake fishes have become
+modified because the means by which they are enabled to migrate so rarely
+occur. It is quite in accordance with this view that some of the smaller
+lakes contain no fishes, because none have ever been conveyed to them.
+Others contain several; and some fishes which have peculiarities of
+constitution or habits which render their transmission somewhat less
+difficult occur in several lakes over a wide area of country, though only
+one appears to be common to the British and Irish lakes. {344}
+
+The manner in which fishes are enabled to migrate from lake to lake is
+unknown, but many suggestions have been made. It is a fact that whirlwinds
+and waterspouts sometimes carry living fish in considerable numbers and
+drop them on the land. Here is one mode which might certainly have acted
+now and then in the course of thousands of years, and the eggs of fishes
+may have been carried with even greater ease. Again we may well suppose
+that some of these fish have once inhabited the streams that enter or flow
+out of the lakes as well as the lakes themselves; and this opens a wide
+field for conjecture as to modes of migration, because we know that rivers
+have sometimes changed their courses to such an extent as to form a union
+with distinct river basins. This has been effected either by floods rising
+over low watersheds, by elevations of the land changing lines of drainage,
+or by ice blocking up valleys and compelling the streams to flow over
+watersheds to find an outlet. This is known to have occurred during the
+glacial epoch, and is especially manifest in the case of the Parallel Roads
+of Glenroy, and it probably affords the true solution of many of the cases
+in which existing species of fish inhabit distinct river basins whether in
+streams or lakes. If a fish thus wandered out of one river-basin into
+another, it might then retire up the streams to some of the lakes, where
+alone it might find conditions favourable to it. By a combination of the
+modes of migration here indicated it is not difficult to understand how so
+many species are now common to the lakes of Wales, Cumberland, and
+Scotland, while others less able to adapt themselves to different
+conditions have survived only in one or two lakes in a single district; or
+these last may have been originally identical with other forms, but have
+become modified by the particular conditions of the lake in which they have
+found themselves isolated.
+
+_Peculiar British Insects._--We now come to the class of insects, and here
+we have much more difficulty in determining what are the actual facts,
+because new species are still being yearly discovered and considerable
+portions of Europe are but imperfectly explored. It often happens that an
+insect is discovered in our islands, and for some {345} years Britain is
+its only recorded locality; but at length it is found on some part of the
+continent, and not unfrequently has been all the time known there, but
+disguised by another name, or by being classed as a variety of some other
+species. This has occurred so often that our best entomologists have come
+to take it for granted that _all_ our supposed peculiar British species are
+really natives of the continent and will one day be found there; and owing
+to this feeling little trouble has been taken to bring together the names
+of such as from time to time remain known from this country only. The view
+of the probable identity of our entire insect-fauna with that of the
+continent has been held by such well-known authorities as the late Mr.
+E. C. Rye and Dr. D. Sharp for the beetles, and by Mr. H. T. Stainton for
+butterflies and moths; but as we have already seen that among two orders of
+vertebrates--birds and fishes--there are undoubtedly peculiar British
+species, it seems to me that all the probabilities are in favour of there
+being a much larger number of peculiar species of insects. In every other
+island where some of the vertebrates are peculiar--as in the Azores, the
+Canaries, the Andaman Islands, and Ceylon--the insects show an equal if not
+a higher proportion of speciality, and there seems no reason whatever why
+the same law should not apply to us. Our climate is undoubtedly very
+distinct from that of any part of the continent, and in Scotland, Ireland,
+and Wales we possess extensive tracts of wild mountainous country where a
+moist uniform climate, an alpine or northern vegetation, and a considerable
+amount of isolation, offer all the conditions requisite for the
+preservation of some species which may have become extinct elsewhere, and
+for the slight modification of others since our last separation from the
+continent. I think, therefore, that it will be very interesting to take
+stock, as it were, of our recorded peculiarities in the insect world, for
+it is only by so doing that we can hope to arrive at any correct solution
+of the question on which there is at present so much difference of opinion.
+For the list of Coleoptera with the accompanying notes I was originally
+indebted to the late Mr. E. C. Rye; and Dr. Sharp also gave me valuable
+information as to the recent {346} occurrence of some of the supposed
+peculiar species on the continent. The list has now been revised by the
+Rev. Canon Fowler, author of the best modern work on the British
+Coleoptera, who has kindly furnished some valuable notes.
+
+For the Lepidoptera I first noted all the species and varieties marked as
+British only in Staudinger's Catalogue of European Lepidoptera. This list
+was carefully corrected by Mr. Stainton, who weeded out all the species
+known by him to have been since discovered, and furnished me with valuable
+information on the distribution and habits of the species. This information
+often has a direct bearing on the probability of the insect being peculiar
+to Britain, and in some cases may be said to explain why it should be so.
+For example, the larvæ of some of our peculiar species of Tineina feed
+during the winter, which they are enabled to do owing to our mild and
+insular climate, but which the severer continental winters render
+impossible. A curious example of the effect this habit may have on
+distribution is afforded by one of our commonest British species,
+_Elachista rufocinerea_, the larva of which mines in the leaves of _Holcus
+mollis_ and other grasses from December to March. This species, though
+common everywhere with us, extending to Scotland and Ireland, is quite
+unknown in similar latitudes on the continent, but appears again in Italy,
+the South of France, and Dalmatia, where the mild winters enable it to live
+in its accustomed manner.
+
+Such cases as this afford an excellent illustration of those changes of
+distribution, dependent probably on recent changes of climate, which may
+have led to the restriction of certain species to our islands. For should
+any change of climate lead to the extinction of the species in South
+Europe, where it is far less abundant than with us, we should have a common
+and wide-spread species entirely restricted to our islands. Other species
+feed in the larva state on our common gorse, a plant found only in limited
+portions of Western and Southern Europe; and the presence of this plant in
+a mild and insular climate such as ours may well be supposed to have led to
+the preservation of some of the numerous species which are or have been
+dependent on it. Since the first edition was {347} published many new
+British species have been discovered, while some of the supposed peculiar
+species have been found on the continent. Information as to these has been
+kindly furnished by Mr. W. Warren, Mr. C. G. Barrett, Lord Walsingham, and
+other students of British Lepidoptera, and the first-named gentleman has
+also looked over the proofs.
+
+Mr. McLachlan has kindly furnished me with some valuable information on
+certain species of Trichoptera or Caddis flies which seem to be peculiar to
+our islands; and this completes the list of orders which have been studied
+with sufficient care to afford materials for such a comparison. We will now
+give the list of peculiar British Insects, beginning with the Lepidoptera
+and adding such notes as have been supplied by the gentlemen already
+referred to.
+
+_List of the Species or Varieties of Lepidoptera which, so far as at
+present known, are confined to the British Islands. (The figures show the
+dates when the species was first described. Species added since the first
+edition are marked with an asterisk.)_
+
+ DIURNI.
+
+ 1. POLYOMMATUS DISPAR. "The large copper." This fine insect, once
+ common in the fens, but now extinct owing to extensive drainage, is
+ generally admitted to be peculiar to our island, at all events as a
+ variety or local form. Its continental ally differs constantly in being
+ smaller and in having smaller spots; but the difference, though
+ constant, is so slight that it is now classed as a variety under the
+ name of _rutilus_. Our insect may therefore be stated to be a
+ well-marked local form of a continental species.
+
+ 2. Lycæna astrarche, _var._ ARTAXERXES. This very distinct form is
+ confined to Scotland and the north of England. The species of which it
+ is considered a variety (more generally known to English entomologists
+ as _P. agestis_) is found in the southern half of England, and almost
+ everywhere on the continent.
+
+ BOMBYCES.
+
+ 3. Lithosia complana, _var._ SERICEA. North of England (1861).
+
+ 4. Hepialus humuli, _var._ HETHLANDICA. Shetland Islands (1865). A
+ remarkable form, in which the male is usually yellow and buff instead
+ of pure white, as in the common form, but exceedingly variable in tint
+ and markings.
+
+ 5. EPICHNOPTERYX RETICELLA. Sheerness, Gravesend, and other localities
+ along the Thames (1847); Hayling Island, Sussex.
+
+ 6. E. pulla, _var._ RADIELLA. Near London, rare (1830?); the species in
+ Central and Southern Europe. (Doubtfully peculiar in Mr. Stainton's
+ opinion.) {348}
+
+ NOCTUÆ.
+
+ 7. Acronycta euphorbiæ, _var._ MYRICÆ. Scotland only (1852). A melanic
+ form of a continental species.
+
+ 8. AGROTIS SUBROSEA. Cambridgeshire and Huntingdonshire fens, perhaps
+ extinct (1835). The _var._ _subcærulea_ is found in Finland and
+ Livonia.
+
+ 9. Agrotis candelarum _var._ ASHWORTHII. South and West (1855).
+ Distinct and not uncommon.
+
+ 10. Luperina luteago, _var._ BARRETTI. Ireland (1864).
+
+ 11. Aporophyla australis, _var._ PASCUEA. South of England (1830). A
+ variety of a species otherwise confined to South Europe.
+
+ 12. Hydræcia nictitans, _var._ PALUDRIS.
+
+ GEOMETRÆ.
+
+ 13. Boarmia gemmaria, _var._ PERFUMARIA. Near London and elsewhere. A
+ large dark variety of a common species.
+
+ 14. *B. repandata, _var._ SODORENSIUM. Outer Hebrides.
+
+ 15. *Emmelesia albulata, _var._ HEBRIDIUM. Outer Hebrides.
+
+ 16. *E. albulata, _var._ THULES. Shetland Islands.
+
+ 17. *Melanippe montanata, _var._ SHETLANDICA. Shetland Islands.
+
+ 18. *M. sociata, _var._ OBSCURATA. Outer Hebrides. A dark form.
+
+ 19. Cidaria albulata, _var._ GRISEATA. East of England (1835). A
+ variety of a species otherwise confined to Central and Southern Europe.
+
+ 20. EUPITHECIA CONSTRICTATA.. Widely spread, but local (1835). Larva on
+ thyme.
+
+ 21. *E. satyrata, _var._ CURZONI. N. Scotland.
+
+ 22. *E. nanata _var._ CURZONI. Shetland Islands.
+
+ PYRALIDINA.
+
+ 23. Aglossa pinguinalis, _var._ STREATFIELDI. Mendip Hills (1830). A
+ remarkable variety of the common "tabby."
+
+ 24. *Scoparia cembræ, _var._ SCOTICA. Scotland (1872).
+
+ 25. *Myelois ceratoniæ, _var._ PRYERELLA. North London (1871).
+
+ 26. *Howoeosoma nimbella, _var._ SAXICOLA. England, Scotland, Isle of
+ Man (1871).
+
+ 27. *Epischnia bankesiella. Isle of Portland (1888).
+
+ TORTRICINA.
+
+ 28. APHELIA NIGROVITTANA. Scotland (1852). A local form of the
+ generally distributed _A. lanceolana_.
+
+ 29. GRAPHOLITA PARVULANA. Isle of Wight (1858). Rare. A distinct
+ species.
+
+ 30. CONCHYLIS ERIGERANA. South-east of England (1866).
+
+ 31. *BRACHYTÆNIA WOODIANA. Herefordshire (1882).
+
+ 32. *Eupoecilia angustana, _var._ THULEANA. Shetland Islands.
+
+ 33. *TORTRIX DONELANA. Connemara, Ireland (1890).
+
+ TINEINA.
+
+ 34. TINEA COCHYLIDELLA. Sanderstead, near Croydon (1854). Unique!
+
+ 35. ACROLEPIA BETULÆTELLA. Yorkshire and Durham (1840). Rare.
+
+ 36. ARGYRESTHIA SEMIFUSCA. North and West of England (1829). Rather
+ scarce. A distinct species.
+
+ 37. GELECHIA DIVISELLA. A fen insect (1856). Rare. {349}
+
+ 38. G. CELERELLA. West of England (1854). A doubtful species.
+
+ 39. *G. TETRAGONELLA. Yorkshire. Norfolk. Salt marshes.
+
+ 40. *G. SPARSICILIELLA. Pembroke.
+
+ 41. *G. PLANTAGINELLA. A salt-marsh species.
+
+ 42. G. OCELLATELLA (Barrett _nec_ Stainton). Bred from _Beta maritima_.
+ Very distinct.
+
+ 43. BRYOTROPHA POLITELLA. Moors of North of England. Norfolk (1854).
+
+ 44. *B. PORTLANDICELLA. Isle of Portland (1890).
+
+ 45. LITA FRATERNELLA. Widely scattered (1834). Larva feeds on shoots of
+ _Stellaria uliginosa_ in spring.
+
+ 46. L. BLANDULELLA. Kent.
+
+ 47. ANACAMPSIS SIRCOMELLA. North and West England (1854). Perhaps a
+ melanic variety of the more widely spread _A. tæniolella_.
+
+ 48. A. IMMACULATELLA. West Wickham (1834). Unique! A distinct species.
+
+ 49. *OECOPHORA WOODIELLA?
+
+ 50. GLYPHIPTERYX CLADIELLA. Eastern Counties (1859). Abundant.
+
+ 51. G. SCHOENICOLELLA. In several localities (1859).
+
+ 52. GRACILARIA STRAMINEELLA. (1850). On birch. Perhaps a local form of
+ _G. elongella_, found on alder.
+
+ 53. ORNIX LOGANELLA. Scotland (1848). Abundant, and a distinct species.
+
+ 54. O. DEVONIELLA. In Devonshire (1854). Unique!
+
+ 55. COLEOPHORA SATURATELLA. South of England (1850). Abundant on broom.
+
+ 56. C. INFLATÆ. South and East of England. On _Silene inflata._ ?
+ continental.
+
+ 57. C. SQUAMOSELLA. Surrey (1856). Very rare, but an obscure species.
+
+ 58. C. SALINELLA. On Sea-coast (1859). Abundant.
+
+ 59. *C. POTENTILLÆ. South of England.
+
+ 60. *C. ADJUNCTELLA. Essex salt marshes. ? Lancashire (1882).
+
+ 61. *C. LIMONIELLA. Isle of Wight. Feeds on _Statice limonium_.
+
+ 62. ELACHISTA FLAVICOMELLA. Dublin (1856). Excessively rare, two
+ specimens only known.
+
+ 63. *E. SCIRPI. Wales and Sussex. Salt marshes.
+
+ 64. E. CONSORTELLA. Scotland (1854). A doubtful species.
+
+ 65. E. MEGERLELLA. Widely distributed (1854). Common. Larva feeds in
+ grass during winter and early spring.
+
+ 66. E. OBLIQUELLA. Near London (1854). Unique!
+
+ 67. E. TRISERIATELLA. South of England (1854). Very local; an obscure
+ species.
+
+ 68. *TINAGMA BETULÆ. East Dorset (1891).
+
+ 69. LITHOCOLLETIS NIGRESCENTELLA. Northumberland (1850). Rare; a dark
+ form of _L. Bremiella_, which is widely distributed.
+
+ 70. *L. ANDERIDÆ. Sussex. Dorset (1886).
+
+ 71. L. IRRADIELLA. North Britain (1854). A northern form of the more
+ southern and wide-spread _L. lautella_.
+
+ 72. L. TRIGUTTELLA. Sanderstead, near Croydon (1848). Unique! very
+ peculiar.
+
+ 73. L. ULICICOLELLA. In a few wide-spread localities (1854). A peculiar
+ form.
+
+ 74. L. CALEDONIELLA. North Britain (1854). A local variety of the more
+ widespread _L. corylifoliella_. {350}
+
+ 75. L. DUNNINGIELLA. North of England (1852). A somewhat doubtful
+ species.
+
+ 76. BUCCULATRIX DEMARYELLA. Widely distributed (1848). Rather common.
+
+ 77. TRIFURCULA SQUAMATELLA. South of England (1854). A doubtful
+ species.
+
+ 78. NEPTICULA IGNOBILIELLA. Widely scattered (1854). On hawthorn, not
+ common. ? on continent.
+
+ 79. N. POTERII. South of England (1858). Bred from Larvæ in _Poterium
+ sanguisorba_.
+
+ 80. N. QUINQUELLA. South of England (1848). On oak leaves, very local.
+ ? continental.
+
+ 81. N. APICELLA. Local (1854). Probably confused with allied species on
+ the continent.
+
+ 82. N. HEADLEYELLA. Local (1854). A rare species.
+
+ 83. *N. HODGKINSONI. Lancashire.
+
+ 84. *N. WOOLHOPIELLA. Herefordshire.
+
+ 85. *N. SERELLA. Westmoreland and S. England.
+
+ 86. *N. AUROMARGINELLA. Dorset (1890).
+
+ 87. *MICROPTERYX SANGII. (1891).
+
+ 88. *M. SALOPIELLA.
+
+ PTEROPHORINA.
+
+ 89. AGDISTIS BENNETTI. East coast. I. of Wight (1840). Common on
+ _Statice limonium_.
+
+We have here a list of eighty-nine species, which, according to the best
+authorities, are, in the present state of our knowledge, peculiar to
+Britain. It is a curious fact that no less than fifty of these have been
+described more than twenty-five years; and as during all that time they
+have not been recognised on the continent, notwithstanding that good
+coloured figures exist of almost all of them, it seems highly probable that
+many of them are really confined to our island. At the same time we must
+not apply this argument too rigidly, for the very day before my visit to
+Mr. Stainton he had received a letter from Professor Zeller announcing the
+discovery on the continent of a species of our last family, Pterophorina,
+which for more than forty years had been considered to be exclusively
+British. This insect, _Platyptilia similidactyla_ (_Pterophorus
+isodactylus_, Stainton's _Manual_), had been taken rarely in the extreme
+north and south of our islands--Teignmouth and Orkney, a fact which seemed
+somewhat indicative of its being a straggler. Again, seven of the species
+are unique, that is, have only been captured once; and it may be supposed
+that, as they are so rare as to have been found only once in England, they
+may be all {351} equally rare and not yet found on the continent. But this
+is hardly in accordance with the laws of distribution. Widely scattered
+species are generally abundant in some localities; while, when a species is
+on the point of extinction, it must for a time be very rare in the single
+locality where it last maintains itself. It is then more probable that some
+of these unique species represent such as are almost extinct, than that
+they have a wide range and are equally rare everywhere; and the peculiarity
+of our insular climate, combined with our varied soil and vegetation, offer
+conditions which may favour the survival of some species with us after they
+have become extinct on the continent.
+
+Of the sixty-nine species recorded in my first edition fourteen have been
+since discovered on the continent, while no less than twenty-two species
+and eleven varieties have been added to the list. As we can hardly suppose
+continental entomologists to be less thorough collectors than ourselves, it
+ought to be more and more difficult to find any insects which are unknown
+on the continent if all ours really exist there; and the fact that the list
+of apparently peculiar British species is an increasing one renders it
+probable that many of them are not only apparently but really so. Both
+general considerations dependent on the known laws of distribution, and the
+peculiar habits, conspicuous appearance, and restricted range, of many of
+our species, alike indicate that some considerable proportion of them will
+remain permanently as peculiar British species.
+
+We will now pass on to the Coleoptera, or beetles, an order which has been
+of late years energetically collected and carefully studied by British
+entomologists.
+
+_List of the Species and Varieties of Beetles which, so far as at present
+known, are confined to the British Islands. Those added since the first
+edition are marked with an asterisk._
+
+ CARABIDÆ.
+
+ 1. *Bembidium saxatile, _var._ VECTENSIS (Fowler). Isle of Wight.
+
+ 2. DROMIUS VECTENSIS (Rye). Common in the Isle of Wight, also in Kent,
+ and at Weymouth and Seaton. Closely allied to _D. sigma_.
+
+ 3. Harpalus latus, _var._ METALLESCENS (Rye). Unique, but very marked!
+ South coast. "Perhaps a sport or a hybrid" (Fowler).
+
+ 4. ACUPALPUS DERELICTUS (Dawson). Unique! North Kent. Canon Fowler
+ thinks it may be a variety of _A. dorsalis_. {352}
+
+ DYTICIDÆ.
+
+ 5. *Acilius sulcatus, _var._ SCOTICUS (Curtis). Scotland. A melanic
+ variety.
+
+ HELOPHORIDÆ.
+
+ 6. OCHTHEBIUS POWERI (Rye). Very marked. S. coast. A few specimens
+ only.
+
+ 7. *O. ÆNEUS (Steph).
+
+ BRACHYELYTRA.
+
+ 8. OCYUSA HIBERNICA (Rye). Ireland, mountain tops, and at Braemar.
+
+ 9. *OXYPODA TARDA (Sharp).
+
+ 10. ,, PECTITA (Sharp). Scotland.
+
+ 11. ,, VERECUNDA (Sharp). Scotland, also London districts.
+
+ 12. HOMALOTA DIVERSA (Sharp).
+
+ 13. ,, FULVIPENNIS (Rye).
+
+ 14. ,, OBLONGIUSCULA (Sharp). Scotland, also England and Ireland.
+
+ 15. ,, PRINCEPS (Sharp). A coast insect.
+
+ 16. ,, CURTIPENNIS (Sharp). Scotland and near Birmingham.
+
+ 17. H. levana, _var._ SETIGERA (Sharp).
+
+ 18. STENUS OSCILLATOR (Rye). Unique! South coast. May be a hybrid.
+
+ 19. TROGOPHLÆUS SPINICOLLIS (Rye). Mersey estuary, unique! Most
+ distinguishable, nothing like it in Europe. Perhaps imported from
+ another continent.
+
+ 20. EUDECTUS WHITEI (Sharp). Scotch hills. A variety of _E. Giraudi_ of
+ Germany (the only European species) _fide_ Kraatz (Sharp).
+
+ 21. HOMALIUM RUGULIPENNE (Rye). Exceedingly marked form. Northern and
+ western coasts; rare.
+
+ 22. *MYCETOPORUS MONTICOLA (Fowler). Cheviots and Inverness-shire.
+
+ SCYDMÆNIDÆ.
+
+ 23. *SCYDMÆNUS POWERI (Fowler) S. England. A recent discovery.
+
+ 24. *S. PLANIFRONS (Fowler). ,, ,,
+
+ PSELAPHIDÆ.
+
+ 25. BRYAXIS COTUS (De Sauley). Scotland.
+
+ 26. BYTHINUS GLABRATUS (Rye). Sussex coast; also Isle of Wight; a few
+ specimens; very distinguishable; myrmecophilous (lives in ants' nests).
+
+ TRICHOPTERYGIDÆ.
+
+ 27. PTINELLA MARIA (Matthews) Derbyshire.
+
+ 28. TRICHOPTERYX SARÆ ( ,, ) Notts.
+
+ 29. ,, POWERI ( ,, ) Oxon.
+
+ 30. ,, EDITHIA ( ,, ) Kent.
+
+ 31. ,, *ANGUSTA ( ,, ) Leicestershire.
+
+ 32. ,, KIRBII ( ,, ) Norfolk.
+
+ 33. ,, FRATERCULA ( ,, )
+
+ 34. ,, WATERHOUSII ( ,, )
+
+ 35. ,, CHAMPIONIS ( ,, ) Wicken Fen.
+
+ 36. ,, JANSONI ( ,, ) Leicestershire.
+
+ 37. ,, SUFFOCATA (Haliday). Ireland, Co. Cork.
+
+ 38. ,, CARBONARIA (Matthews). Notts.
+
+ {353} 39. Ptilium halidayi (Matthews). Sherwood Forest.
+
+ 40. ,, caledonicum (Sharp). Scotland; very marked form.
+
+ 41. ,, insigne (Matthews). London district.
+
+ 42. *ORTHOPERUS MUNDUS (Matthews). Oxfordshire.
+
+ 43. *O. PUNCTULATUS (Matthews). Lincolnshire.
+
+ ANISOTOMIDÆ.
+
+ 44. AGATHIDIUM RHINOCEROS (Sharp). Old fir-woods in Perthshire; local,
+ many specimens; a very marked species.
+
+ 45. ANISOTOMA SIMILATA (Rye). South of England. Two specimens.
+
+ 46. ,, LUNICOLLIS (Rye). North-east and South of England, a very
+ marked form; several specimens.
+
+ PHALACRIDÆ.
+
+ 47. PHALACRUS BRISOUTI (Rye). South of England. Rare. "Perhaps a small
+ form of _P. coruscus_" (Fowler).
+
+ CRYPTOPHAGIDÆ.
+
+ 48. ATOMARIA DIVISA (Rye). Unique! South of England.
+
+ LATHRIDIIDÆ.
+
+ 49. Melanopthalma transversalis, _var._ WOLLASTONI (Waterhouse). South
+ coast, and Lincolnshire.
+
+ BYRRHIDÆ.
+
+ 50. SYNCALYPTA HIRSUTA (Sharp). South of England, local. "Closely
+ allied to _S. setigera_" (Fowler).
+
+ MORDELLIDÆ.
+
+ 51. *ANASPIS SEPTENTRIONALIS. Scotland (1891). (Champion.)
+
+ 52. * ,, GARNEYSI (Fowler). London District. (1890.)
+
+ TELEPHORIDÆ.
+
+ 53. TELEPHORUS DARWINIANUS (Sharp). Scotland, sea-coast. A stunted form
+ of abnormal habits. Perhaps a variety of _T. lituratus_.
+
+ CYPHONIDÆ.
+
+ 54. CYPHON PUNCTIPENNIS (Sharp). Scotland.
+
+ ANTHICIDÆ.
+
+ 55. ANTHICUS SALINUS (Crotch). South coast.
+
+ 56. ,, SCOTICUS (Rye). Loch Leven; very distinct; many specimens.
+
+ CIOIDÆ.
+
+ 57. *CIS BILAMELLATUS (Wood). West Wickham, Kent. "Perhaps imported.
+ Has the appearance of an exotic Cis" (Fowler).
+
+ TOMICIDÆ.
+
+ 58. *Pityopthorus lichtensteinii, _var._ SCOTICUS (Blandford).
+ Scotland.
+
+ CURCULIONIDÆ.
+
+ 59. Ceuthorhynchus contractus, _var._ PALLIPES (Crotch). Lundy Island;
+ several specimens. A curious variety only known from this island.
+
+ 60. LIOSOMUS TROGLODYTES (Rye). A very queer form. Two or three
+ specimens. South of England.
+
+ 61. *Orcheites ilicis, _var._ NIGRIPES (Fowler). London District.
+ (1890.)
+
+ {354}
+
+ 62. APION RYEI (Blackburn). Shetland Islands. Several specimens.
+ Perhaps a _var._ of _A. fagi_.
+
+ CHRYSOMELIDÆ.
+
+ 63. Chrysomela staphylea, _var._ SHARPI (Fowler). Solway district.
+
+ HALTICIDÆ.
+
+ 64. LONGITARSUS AGILIS (Rye). South of England; many specimens.
+
+ 65. ,, DISTINGUENDA (Rye). South of England; many specimens.
+
+ 66. PSYLLIODES LURIDIPENNIS (Kutschera). Lundy Island. A very curious
+ form, not uncommon in this small island, to which it appears to be
+ confined. "An extreme and local variety of _P. chrysocephala_"
+ (Fowler).
+
+ COCCINELLIDÆ.
+
+ 67. SCYMNUS LIVIDUS (Bold). Northumberland. A doubtful species.
+
+Of the sixty-seven species and varieties of beetles in the preceding list,
+a considerable number no doubt owe their presence there to the fact that
+they have not yet been discovered or recognised on the continent. This is
+almost certainly the case with many of those which have been separated from
+other species by very minute and obscure characters, and especially with
+the excessively minute Trichopterygidæ described by Mr. Matthews. There are
+others, however, to which this mode of getting rid of them will not apply,
+as they are so marked as to be at once recognised by any competent
+entomologist, and often so plentiful that they can be easily obtained when
+searched for. The peculiar species of Apion in the Shetland Islands is
+interesting, and may be connected with the very peculiar climatal
+conditions there prevailing, which have led in some cases to a change of
+habits, so that a species of weevil (_Otiorhynchus maurus_) always found on
+mountain sides in Scotland here occurs on the sea-shore. Still more curious
+is the occurrence of two distinct forms (a species and a well-marked
+variety) on the small granitic Lundy Island in the Bristol Channel. This
+island is about three miles long and twelve from the coast of Devonshire,
+consisting mainly of granite with a little of the Devonian formation, and
+the presence here of peculiar insects can only be due to isolation with
+special conditions, and immunity from enemies or competing forms. When we
+consider the similar islands off {355} the coast of Scotland and Ireland,
+with the Isle of Man and the Scilly Islands, none of which have been yet
+thoroughly explored for beetles, it is probable that many similar examples
+of peculiar isolated forms remain to be discovered.
+
+Looking, then, at what seem to me the probabilities of the case from the
+standpoint of evolution and natural selection, and giving due weight to the
+facts of local distribution as they are actually presented to us, I am
+forced to differ from the opinion held by our best entomological
+authorities, and to believe that some at least, perhaps many, of the
+species which, in the present state of our knowledge, appear to be peculiar
+to our islands, are, not only apparently, but really, so peculiar.
+
+I am indebted to Mr. Robert McLachlan for the following information on
+certain Trichopterous Neuroptera (or caddis-flies) which appear to be
+confined to our islands. The peculiar aquatic habits of the larvæ of these
+insects, some living in ponds or rivers, others in lakes, and others again
+only in clear mountain streams, render it not improbable that some of them
+should have become isolated and preserved in our islands, or that they
+should be modified owing to such isolation.
+
+_Trichoptera peculiar to the British Isles._
+
+ 1. PHILOPOTAMUS INSULARIS. (? A variety of _P. montanus_.)--This can
+ hardly be termed a British species or variety, because, so far as at
+ present known, it is peculiar to the Island of Guernsey. It agrees
+ structurally with _P. montanus_, a species found both in Britain and on
+ the continent, but it differs in its strikingly yellow colour, and less
+ pronounced markings. All the specimens from Guernsey are alike, and
+ resident entomologists assured Mr. McLachlan that no other kind is
+ known. Strange to say, some examples from Jersey differ considerably,
+ resembling the common European and British form. Even should this
+ peculiar variety be at some future time found on the continent it would
+ still be a remarkable fact that the form of insect inhabiting two small
+ islands only twenty miles apart should constantly differ; but as Jersey
+ is between Guernsey and the coast, it seems just possible that the more
+ insular conditions, and perhaps some peculiarity of the soil and water
+ in the former island, have really led to the production or preservation
+ of a well-marked variety of insect. In the first edition of this work
+ two other species were named as then, peculiar to Britain--Setodes
+ argentipunctella and Rhyacophila munda, but both have now been taken on
+ the continent.
+
+ 2. MESOPHYLAX IMPUNCTATUS, _var._ ZETLANDICUS.--A variety of a South
+ and Central European species, one specimen of which has been found in
+ Dumfriesshire. The variety is distinguished by its small size and dark
+ colour.
+
+{356}
+
+_Land and Freshwater Shells._--In the first edition of this work four
+species were noted as being, so far as was then known, exclusively British.
+Two of these, _Cyclas pisidioides_ (now called _Sphærium pisidioides_) and
+_Geomalacus maculosus_, have been discovered on the continent, but the
+other two remain still apparently confined to these islands; and to these
+another has been added by the discovery of a new species of Hydrobia in the
+estuary of the Thames. The peculiar species now stands as follows:--
+
+ 1. LIMNEA INVOLUTA.--A pond snail with a small polished amber-coloured
+ shell found only in a small alpine lake and its inflowing stream on
+ Cromagloun mountain near the lakes of Killarney. It was discovered in
+ 1838, and has frequently been obtained since in the same locality. It
+ is sometimes classed as a variety of _Limnea peregra_, and is at all
+ events closely allied to that species.
+
+ 2. HYDROBIA JENKINSII.--A small shell of the family Rissoidæ inhabiting
+ the Thames estuary both in Essex and Kent. It was discovered only a few
+ years ago, and was first described in 1889.
+
+ 3. ASSIMINEA GRAYANA.--A small estuarine pulmonobranch found on the
+ banks of the Thames between Greenwich and Gravesend, on mud at the
+ roots of aquatic plants. It has been discovered more than sixty years.
+
+But besides the above-named species there are a considerable number of
+well-marked varieties of shells which seem to be peculiar to our islands. A
+list of these has been kindly furnished me by Mr. Theo. D. A. Cockerell,
+who has paid much attention to the subject; and after omitting all those
+whose peculiarities are very slight or whose absence from the continent is
+doubtful, there remain a series of forms some of which are in all
+probability really endemic with us. This is the more probable from the fact
+that an introduced colony of _Helix nemoralis_ at Lexington, Virginia,
+presents numerous varieties among which are several which do not occur in
+Europe.[84] The following list is therefore given in the hope that it may
+be useful in calling attention to those varieties which are not yet
+positively known to occur elsewhere than in our islands, and {357} thus
+lead, ultimately, to a more accurate knowledge of the facts. It is only by
+obtaining a full knowledge of varieties, their distribution and their
+comparative stability, that we can ever hope to detect the exact process by
+which nature works in the formation of species.
+
+LIST OF THE SPECIES AND VARIETIES OF LAND AND FRESHWATER SHELLS WHICH, SO
+FAR AS AT PRESENT KNOWN, ARE BELIEVED TO BE PECULIAR TO THE BRITISH ISLES
+OR NOT FOUND ON THE CONTINENT.
+
+ LIMACIDÆ.
+
+ 1. Limax marginatus, _var._ MACULATUS. Ireland; frequent, very
+ distinct.
+
+ 2. ,, ,, ,, DECIPIENS. Ireland and England.
+
+ 3. ,, flavus, _var._ SUFFUSUS. England; Melanic form.
+
+ 4. ,, ,, ,, GRISEUS. England; Melanic form.
+
+ 5. Agriolimax agrestis, _var._ NIGER. Yorkshire. Melanic. Azores.
+
+ 6. ,, ,, ,, GRISEUS. England. Melanic.
+
+ 7. Amalia gagates, _var._ RAVA. W. of England.
+
+ 8. ,, sowerbyi, _var._ RUSTICA. England.
+
+ 9. ,, ,, ,, NIGRESCENS. Surrey and Middlesex.
+
+ 10. ,, ,, ,, BICOLOR. Ealing.
+
+ 11. Hyalina crystallina, _var._ COMPLANATA. Near Bristol.
+
+ 12. ,, fulva, _var._ ALDERI.
+
+ 13. Vitrina pellucida, _var._ DEPRESSIUSCULA. S. England, Wales.
+
+ HELICIDÆ.
+
+ 14. Arion ater, _var._ ALBO-LATERALIS. England, Wales, Isle of Man;
+ very distinct.
+
+ 15. ,, hortensis, _var._ FALLAX. England. Common at Boxhill.
+
+ 16. GEOMALACUS MACULOSUS. Kerry and Cork. Three varieties have been
+ described, one of which occurs in Portugal.
+
+ 17. Helix aspersa, _var._ LUTESCENS. England. Not rare perhaps in
+ France.
+
+ 18. ,, nemoralis, _var._ HIBERNICA. Ireland.
+
+ 19. ,, rufescens, _var._ MANCHESTERIENSIS. England.
+
+ 20. ,, hispida, _var._ SUBGLOBOSA. England.
+
+ 21. ,, ,, ,, DEPILATA. England.
+
+ 22. ,, ,, ,, MINOR. England, Ireland.
+
+ 23. ,, granulata, _var._ CORNEA. Lulworth, Dorset.
+
+ 24. ,, virgata, _var._ SUBAPERTA. Bath.
+
+ 25. ,, ,, ,, SUBGLOBOSA. England, Wales, Bantry Bay.
+
+ 26. ,, ,, ,, CARINATA. Wareham, Dorset.
+
+ 27. ,, caperata, _var._ MAJOR. England, Wales, Scotland. Distinct.
+
+ 28. ,, ,, ,, NANA. England.
+
+ 29. ,, ,, ,, SUBSCALARIS. Wales, Ireland.
+
+ 30. ,, ,, ,, ALTERNATA. England, Kent.
+
+ 31. ,, acuta, _var._ NIGRESCENS. England.
+
+ PUPIDÆ.
+
+ 32. Pupa anglica, _var._ PALLIDA. Not rare.
+
+ 33. ,, lilljeborgi, _var._ BIDENTATA. Ireland.
+
+ {358} 34. ,, pygmea, _var._ PALLIDA. Dorset and Devon.
+
+ 35. Clausilia rugosa, _var._ PARVULA. Ireland.
+
+ STENOGYRIDÆ.
+
+ 36. Cochlicopa lubrica, _var._ HYALINA. Wales, Scotland.
+
+ 37. Coecilianella acicula, _var._ ANGLICA. England.
+
+ SUCCINEIDÆ.
+
+ 38. Succinea putris, _var._ SOLIDULA. Wiltshire.
+
+ 39. ,, virescens, _var._ AUREA. Ireland.
+
+ 40. ,, pfeifferi, ,, RUFESCENS. England, Ireland.
+
+ 41. ,, ,, ,, MINOR. England.
+
+ LIMNÆIDÆ.
+
+ 42. Planorbis fontanus, _var._ MINOR. England.
+
+ 43. ,, carinatus, ,, DISCIFORMIS. England.
+
+ 44. ,, contortus, ,, EXCAVATUS. Ireland.
+
+ 45. ,, ,, ,, MINOR.
+
+ 46. Physa fontinalus, _var._ OBLONGA. England, Wales, Ireland.
+
+ 47. LIMNÆA INVOLUTA. Ireland.
+
+ 48. Limnæa glutinosa, _var._ MUCRONATA.
+
+ 49. ,, peregra, _var._ BURNETTI. Scotland. Very distinct.
+
+ 50. ,, ,, ,, LACUSTRIS. Perhaps in C. Verde Islands.
+
+ 51. ,, ,, ,, MARITIMA. Great Britain.
+
+ 52. ,, ,, ,, LINEATA. England.
+
+ 53. ,, ,, ,, STAGNALIFORMIS. England.
+
+ 54. ,, stagnalis, _var._ ELAGANTULA. Curious. In a pond at
+ Chislehurst.
+
+ 55. ,, palustris, _var._ CONICA. England, Ireland.
+
+ 56. ,, ,, ,, TINCTA. England, Wales.
+
+ 57. ,, ,, ,, ALBIDA. England.
+
+ 58. ,, truncatula, _var._ ELEGANS. England, Ireland. Distinct.
+
+ 59. ,, ,, ,, FUSCA. Wales.
+
+ 60. Ancylus lacustris, _var._ COMPRESSUS. England.
+
+ PALUDINIDÆ.
+
+ 61. Paludina vivipara, _var._ EFASCIATA. England. Not uncommon.
+
+ 62. ,, ,, ,, ATROPURPUREA. Pontypool.
+
+ RISSOIDÆ.
+
+ 63. HYDROBIA JENKINSII. Thames Estuary.
+
+ 64. ,, ventrosa, _var._ MINOR.
+
+ 65. ,, ,, ,, DECOLLATA.
+
+ 66. ,, ,, ,, OVATA.
+
+ 67. ,, ,, ,, ELONGATA.
+
+ 68. ,, ,, ,, PELLUCIDA.
+
+ CYRENIDÆ.
+
+ 69. Sphærium corneum, _var._ COMPRESSUM.
+
+ 70. ,, ,, ,, MINOR.
+
+ 71. ,, ,, ,, STAGNICOLA.
+
+ 72. ,, ovale, _var._ PALLIDUM. England.
+
+ 73. ,, lacustre, _var._ ROTUNDUM. Wales.
+
+ 74. Pisidium pusillum, _var._ GRANDIS.
+
+ 75. ,, ,, ,, CIRCULARE. Wales.
+
+ 76. ,, nitidum, _var._ GLOBOSUM.
+
+ {359} UNIONIDÆ.
+
+ 77. Unio tumidus, _var._ RICHENSIS. Regent's Park. Peculiar form.
+
+ 78. ,, pictorum, _var._ LATIOR. England.
+
+ 79. ,, ,, ,, COMPRESSUS. England.
+
+ 80. ,, margaritifer, _var._ OLIVACEUS.
+
+ 81. Anodonta cygnæa, _var._ INCRASSATA. England.
+
+ 82. ,, ,, ,, PALLIDA. England, Ireland.
+
+ ESTUARINE OR MARINE PULMONOTRANCHS.
+
+ 83. ASSIMINEA GRAYANA. Thames Estuary.
+
+_Peculiarities of the British Flora._--Thinking it probable that there must
+also be some peculiar British plants, but not finding any enumeration of
+such in the _British Floras_ of Babington, Hooker, or Bentham, I applied to
+the greatest living authority on the distribution of British plants--the
+late Mr. H. C. Watson, who very kindly gave me the information I required,
+and I cannot do better than quote his words: "It may be stated pretty
+confidently that there is no 'species' (generally accepted among botanists
+as a good species) peculiar to the British Isles. True, during the past
+hundred years, nominally new species have been named and described on
+British specimens only, from time to time. But these have gradually come to
+be identified with species described elsewhere under other names--or they
+have been reduced in rank by succeeding botanists, and placed or replaced
+as varieties of more widely distributed species. In his _British Rubi_
+Professor Babington includes as good species, some half-dozen which he has,
+apparently, not identified with any foreign species or variety. None of
+these are accepted as 'true species,' nor even as 'sub-species' in the
+_Students' Flora_, where the brambles are described by Baker, a botanist
+well acquainted with the plants of Britain. And as all these nominal
+species of Rubi are of late creation, they have truly never been subjected
+to real or critical tests as 'species.'"
+
+In my first edition I was only able to name four species, sub-species, or
+varieties of flowering plants which were believed to be unknown on the
+continent. But much attention has of late years been paid to the critical
+examination of British plants in comparison with continental specimens, and
+I am now enabled to give a much more {360} extensive list of the species or
+forms which at present seem to be peculiar. For the following list I am
+primarily indebted to Mr. Arthur Bennett of Croydon. Sir Joseph Hooker has
+been so kind as to examine it carefully and to give me his conclusions on
+the relative value of the differences of the several forms, and Mr. Baker,
+of Kew, has also assisted with his extensive knowledge of British plants.
+
+ LIST OF SPECIES, SUB-SPECIES, AND VARIETIES OF FLOWERING PLANTS FOUND
+ IN GREAT BRITAIN OR IRELAND, BUT NOT AT PRESENT KNOWN IN CONTINENTAL
+ EUROPE. BY ARTHUR BENNETT, F.L.S. THE MOST DISTINCT AND BEST DETERMINED
+ FORMS ARE MARKED WITH AN ASTERISK.
+
+ 1. *Caltha radicans (Forst.). "A much disputed species, or form of _C.
+ palustris_. It is a relatively rare plant." (J. D. H.) "Certainly
+ distinct from the Scandinavian form." (Ar. Bennett.)
+
+ 2. *Arabis petræa (Lam.) _var._ grandifolia (Druce). Scotch mountains.
+ "The larger flowers alone distinguish this." (J. D. H.)
+
+ 3. Arabis ciliata (R. Br.). In Nyman's _Conspectus Floræ Europææ_ this
+ species is given as found in England and Ireland only. "A very much
+ disputed form of a plant of very wide distribution in Europe and North
+ America." (J. D. H.)
+
+ 4. Brassica monensis (Huds.). "This and the continental _B.
+ cheiranthus_ (also found in Cornwall) are barely distinguishable from
+ one another." (J. D. H.)
+
+ 5. Diplotaxis muralis (D. C.) _var._ Babingtonii (Syme). South of
+ England. "A biennial or perennial form; considered to be a denizen by
+ Watson." (J. D. H.)
+
+ 6. *Helianthemum guttatum (Mill), _var._ Breweri (Planch). Anglesea.
+ "Very doubtful local plant. _H. guttatum_ (true) has lately been found
+ in the same locality." (J. D. H.)
+
+ 7. *Polygala vulgaris (L.), _var._ grandiflora (Bab). Sligo, Ireland.
+ "A very distinct variety." (J. D. H.)
+
+ 8. Viola lutea (Huds.), _var._ amoena (Symons). "_V. lutea_ itself is
+ considered to be a form of _V. tricolor_, and _V. amoena_ the better
+ coloured of the two forms of _V. lutea_." (J. D. H.)
+
+ 9. *Cerastium arcticum (Lange), _var._ Edmonstonii (Beeby). Shetland
+ Is. "But _C. arcticum_ is referable to the very variable _C. alpinum_."
+ (J. D. H.) "Near to the European _C. latifolium_." (Ar. Bennett.)
+
+ 10. *Geranium sanguineum (L.), _var._ Lancastriense (With.).
+ Lancashire. "A prostrate local form growing out of its native soil in
+ sand by the sea." (J. D. H.) Mr. Bennett writes: "I have grown _G.
+ sanguineum_ and its prostrate variety in sand, and neither became
+ Lancastriense."
+
+ 11. Genista tinctoria (L.), _var._ humifusa (Dickson). Cornwall. "A
+ decumbent hairy form confined to the Lizard." (J. D. H.)
+
+ 12. Cytisus scoparius (Link.), _var._ prostratus (Bailey). Cornwall. "A
+ prostrate form." (J. D. H.)
+
+ 13. Anthyllis vulneraria (L.), _var._ ovata (Bab.). Shetland Is. "A
+ slight variety." (J. D. H.)
+
+ 14. *Trifolium repens (L.), _var._ Townsendii (Bab.). Scilly Isles. "A
+ {361} well-marked form by its rose-purple flowers. Confined to the
+ Scilly Isles." (J. D. H.)
+
+ 15. *Rosa involuta (Sm.), _var._ Wilsoni. (Borrer.) Wales. "There are a
+ multitude of forms or varieties of _R. involuta_, and _R. wilsoni_ is
+ one of the best-marked, found on the Menai Straits and Derry."
+ (J. D. H.)
+
+ 16. Rosa involuta _var._ gracilis (Woods). "This is considered by many
+ as one of the commonest forms of _R. involuta_." (J. D. H.)
+
+ 17. Rosa involuta _var._ Nicholsoni (Crepin). "Another slight variety
+ of _R. involuta_." (J. D. H.)
+
+ 18. Rosa involuta _var._ Woodsiana (Groves). "A Wimbledon Common
+ variety of _R. villosa_." (J. D. H.)
+
+ 19. Rosa involuta _var._ Grovesii (Baker). "Mr. Baker thinks this of no
+ account." (J. D. H.)
+
+ 20. Rubus echinatus (Lind.). "A variety of the widely spread _R.
+ Radula_, itself a form of _R. fruticosus_." (J. D. H.)
+
+ 21. *Rubus longithyrsiger (Lees). "Mr. Baker informs me that this is a
+ very distinct plant never yet found on the continent." (J. D. H.)
+
+ 22. Pyrus aria (Sm.) _var._ rupicola (Syme). "A very local form,
+ confined to Gt. Britain, and owing its characters to its starved
+ position." (Baker.)
+
+ 23. Callitriche obtusangula (Le Gall), _var._ Lachii (Warren).
+ Cheshire. "This is intermediate between two sub-species of _C. verna_."
+ (J. D. H.)
+
+ 24. *Oenanthe fluviatilis (Coleman). South of England. "The fluitant
+ form of _Æ. Phellandrium_." (J. D. H.)
+
+ 25. Anthemis arvensis (L.), _var._ anglica (Spreng). N. Coast of
+ England. "A maritime form with more fleshy leaves formerly found near
+ Durham. It has other very trifling characters." (J. D. H.)
+
+ 26. Arctium intermedium (Bab.). "There are two sub-species of _A.
+ lappa_, _majus_ and _minus_, each with varieties, and this is one of
+ the intermediates." (J. D. H.)
+
+ 27. Hieracium holosericium (Backh.). Scotch Alps.
+
+ 28. H. gracilentum (Backh.). ,,
+
+ 29. H. lingulatum (Backh.). ,, A var. of this in
+ Scandinavia.
+
+ 30. H. senescens (Backh.). ,,
+
+ 31. H. chrysanthenum (Backh.). ,,
+
+ 32. H. iricum (Fr.). Teesdale and Scotland.
+
+ 33. H. gibsoni (Backh.). Yorkshire and Westmoreland.
+
+ 34. Hieracium nitidum (Backh.). Lower glens of the Scotch Alps. Mr.
+ Bennett writes:--"The following Hieracia have been named by Mr. F. J.
+ Hanbury _as endemic forms_. One can only safely say they are certainly
+ not known in Scandinavia, as they have all been submitted to Dr.
+ Lindeberg. But usually Scotch species are not represented in Central
+ Europe to any great extent, though several do occur. Still these new
+ forms ought to be critically compared with all Dr. Peters' new
+ species."
+
+ 35. H. Langewellense (Hanb.). Caithness.
+
+ 36. H. pollinarium (Hanb.). Sutherland.
+
+ 37. H. scoticum (Hanb.). Sutherland and Caithness.
+
+ 38. H. Backhousei (Hanb.). Aberdeen, Banff, Inverness.
+
+ 39. H. caledonicum (Hanb.). Caithness and Sutherland.
+
+ 40. H. Farrense (Hanb.). Sutherland and Shetland Is.
+
+ 41. H. proximum (Hanb.). Caithness. With regard to all these {362}
+ Hieracia Sir Joseph Hooker and Mr. Baker say:--"No case can be made of
+ these. They are local forms with the shadowest of shady characters."
+ Mr. Bennett writes: "H. iricum and H. Gibsoni are the best marked
+ forms."
+
+ 42. *Campanula rotundifolia (L.), _var._ speciosa (A. G. More). W.
+ Ireland. "Very well distinguished by its large flowers and small calyx
+ lobes, approaching the Swiss C. Scheuzeri." (J. D. H.)
+
+ 43. Statice reticulata (Sm.). "Baker agrees with me that this is also a
+ Mediterranean species." (J. D. H.)
+
+ 44. Erythræa capitata (Willd.), _var._ sphærocephala (Towns.). Isle of
+ Wight. "A form of _E. centaurium_ utterly anomalous in its genus in the
+ insertion of the stamens. A monster rather than a species." (J. D. H.)
+
+ 45. *Erythræa latifolia (Sm.). On the sandy dunes near Liverpool. "A
+ local form." (J. D. H.)
+
+ 46. Myosotis collina (Hoffim.), _var._ Mittenii (Baker). Sussex.
+
+ 47. Veronica officinalis (L.), _var._ hirsuta (Hopk.). Ayr, Scotland.
+
+ 48. Veronica arvensis (L.), _var._ eximia (Towns.). Hampshire.
+
+ 49. Mentha alopecuroides (Hull). Nearest to _M. dulcissima_ (Dum.).
+
+ 50. Mentha pratensis (Sole). Only once found.
+
+ 51. Chenopodium rubrum (L.), _var._ pseudobotryoides (H. C. Watson).
+
+ 52. Salix ferruginea (Forbes). England, Scotland. "Probably a hybrid
+ between _S. viminalis_ and _S. cinerea_." (J. D. H.)
+
+ 53. Salix Grahami (Borr.). Sutherland, Perth. "A hybrid?" (J. D. H.)
+
+ 54. Salix Sadleri (Syme). Aberdeen. "A hybrid?" (J. D. H.)
+
+ 55. *Spiranthes Romanzoviana (Cham.). Ireland (N. America).
+
+ 56. *Sisyrinchium angustifolium (Mill.). Ireland. (Arctic and Temp. N.
+ America.)
+
+ 57. Allium Babingtonii (Borrer). West England, West Ireland. "A form of
+ _A. ampeloprasum_, itself a naturalised species." (J. D. H.)
+
+ 58. *POTAMOGETON LANCEOLATUS (Sm.). Anglesea, Cambridgeshire, Ireland.
+ Mr. Bennett writes:--"Endemic! I have taken a good amount of trouble to
+ ascertain this. Nearly 400 specimens I have distributed all over the
+ world with requests for information as to anything like it. The
+ response is everywhere the same, 'nothing.' The nearest to it occurs in
+ the Duchy of Lauenberg but is referable to _P. heterophyllus_."
+
+ 59. Potamogeton Griffithii (Ar. Bennett). Carnarvon. "Nearest to this
+ is a probable hybrid from N. America, but not identical." (Ar.
+ Bennett.)
+
+ 60. Potamogeton pusillus (L.), _sub-sp._ Sturrockii (Ar. Benn.). Perth.
+
+ 61. Potamogeton pusillus (L.), _var._ rigidus (Ar. Benn.). Orkneys,
+ Shetlands.
+
+ 62. Ruppia rostellata (Koch.), _var._ nana (Bosw.). Orkneys.
+
+ 63. *Eriocaulon septangulare (With.). Hebrides, Ireland. N. America.
+
+ 64. Scirpus uniglumis (Link), _var._ Watsoni (Bab.). Scotland, England.
+ "This is a variety of a sub-species of the common _S. palustris_."
+ (J. D. H.)
+
+ 65. Luzula pilosa (Willd.), _var._ Borreri (Bromf).
+
+ 66. *Carex involuta (Bab.). Cheshire. "A distinct enough plant but
+ probably a hybrid between _C. vesicaria_ and _C. ampullacea_, found in
+ one place only." (J. D. H.)
+
+ 67. Carex glauca (Murr.), _var._ stictocarpa (Sm.). Scotland.
+
+ {363} 68. Carex precox (Jacq.), _var._ capitata (Ar. Benn.). Ireland.
+ "A remarkable plant (monstrosity?) simulating _C. capitata_ (L.)." (Ar.
+ Bennett.)
+
+ 69. *Carex Grahami (Boott). "A mountain form of _C. vesicaria_."
+ (J. D. H.)
+
+ 70. *Spartina Townsendi (Groves). Hampshire. "A distinct but very local
+ form of _S. stricta_, found in one place only." (J. D. H.)
+
+ 71. Agrostis nigra (With.).
+
+ 72. Deschampsia flexuosa (Trin.), _var._ Voirlichensis (J. C. Melvill).
+ Perth.
+
+ 73. *Deyeuxia neglecta (Kunth), _var._ Hookeri (Syme). Ireland. "A
+ distinct variety confined to Lough Neagh." (J. D. H.)
+
+ 74. Glyceria maritima (Willd.), _var._ riparia (Towns.). Hampshire.
+
+ 75. Poa Balfouri (Bab.). Scotland. "An alpine sub-variety of a variety
+ of the protean _P. nemoralis_." (J. D. H.)
+
+In his comments on this extensive list of supposed peculiar British plants,
+Sir Joseph Hooker arrives at the following conclusions:--
+
+ 1. There are four unquestionably distinct species which do not occur in
+ continental Europe: viz.--
+
+ _One_ absolutely endemic species, POTAMOGETON LANCEOLATUS.
+
+ _Three_ American species, SISYRINCHIUM ANGUSTIFOLIUM, SPIRANTHES
+ ROMANZOVIANA, ERIOCAULON SEPTANGULARE.
+
+ 2. There are sixteen endemic varieties of British species, viz.--
+
+ _Eleven_ of more or less variable species, Caltha palustris, _var._
+ RADICANS; Polygala vulgaris, _var._ GRANDIFLORA; Cerastium arcticum,
+ _var._ EDMONSTONII; Trifolium repens, _var._ TOWNSENDII; Rosa involuta,
+ _var._ WILSONI; Rubus fruticosus, _sub-sp._ LONGITHYRSIGER; Campanula
+ rotundifolia, _var._ SPECIOSA; Erythræa centaurium, _sub-sp._
+ LATIFOLIA; Carex involuta, (? Hyb.); Carex vesicaria, _var._ GRAHAMI;
+ Deyeuxia neglecta, _var._ HOOKERI.
+
+ _Five_ of comparatively well limited species. Arabis petræa, _var._
+ GRANDIFOLIA; Helianthemum guttatum, _var._ BREWERI; Geranium
+ sanguineum, _var._ LANCASTRIENSE; Oenanthe Phellandrium, _var._
+ FLUVIATILIS; Spartium stricta, _var._ TOWNSENDI.
+
+The above twenty species are marked in the list with an asterisk. Of the
+remaining fifty-five, Sir Joseph Hooker says, "that for various reasons it
+would not be safe to rely on them as evidence. In most cases the varietal
+form is so very trifling a departure from the type that this may be safely
+set down to a local cause, and is probably not constant. In others the
+plant is doubtfully endemic; in still others a hybrid."
+
+Even should it ultimately prove that of the whole number of the fifty-five
+doubtful forms none are established as peculiar British varieties, the
+number admitted after so {364} rigorous an examination is about what we
+should expect in comparison with the limited amount of speciality we have
+seen to exist in other groups. The three American species which inhabit the
+extreme west and north-west of the British Isles, but are not found on the
+continent of Europe are especially interesting, because they demonstrate
+the existence of some peculiar conditions such as would help to explain the
+presence of the other peculiar species. Whether we suppose these American
+forms to have migrated from America to Europe before the glacial epoch, or
+to be the remnants of a vegetation once spread over the north temperate
+zone, we can only explain their presence with us and not further east by
+something favourable either in our insular climate or in the limited
+competition due to our comparative poverty in species.
+
+About half of the peculiar forms are found in the extreme west or north of
+Britain or in Ireland, where peculiar insular conditions are at a maximum;
+and the influence of these conditions is further shown by the number of
+species of West or South European plants which occur in the same districts.
+
+We may here notice the interesting fact that Ireland possesses no less than
+twenty species or sub-species of flowering plants not found in Britain, and
+some of these _may_ be altogether peculiar. As a whole they show the effect
+of the pre-eminently mild and insular climate of Ireland in extending the
+range of some south European species. The following list of these plants,
+for which I am indebted to Mr. A. G. More, with a few remarks on their
+distribution, will be found interesting:--
+
+LIST OF IRISH FLOWERING PLANTS WHICH ARE NOT FOUND IN BRITAIN.
+
+ 1. _Polygala vulgaris_ (_var._ grandiflora). Sligo.
+
+ 2. _Campanula rotundifolia_ (_var._ speciosa). W. Ireland.
+
+ 3. _Arenaria ciliata._ W. Ireland (also Auvergne, Pyrenees, Crete).
+
+ 4. _Saxifraga umbrosa._ W. Ireland (also Pyrenees, N. Spain, Portugal).
+
+ 5. ,, _geum._ S. W. Ireland (also Pyrenees).
+
+ 6. ,, _hirsuta._ S. W. Ireland (also Pyrenees).
+
+ 7. _Inula salicina._ W. Ireland (Scandinavia, Middle and South Europe).
+
+ 8. _Erica mediterranea._ W. Ireland (W. France, Spain, Portugal).
+
+ 9. ,, _mackaiana_ (_tetralix_ sub.-sp.) W. Ireland (Spain).
+
+ 10. _Arbutus unedo._ S. W. Ireland (W. of France, Spain, Portugal and
+ shores of Mediterranean).
+
+ 11. _Dabeocia polifolia._ W. Ireland (W. of France, Spain and
+ Portugal).
+
+ {365} 12. _Pinguicula grandiflora._ S. W. Ireland (Spain, Pyrenees,
+ Alps of France and Switzerland).
+
+ 13. _Neotinea intacta._ W. Ireland (S. France, Portugal, Spain, and
+ shores of Mediterranean).
+
+ 14. _Spiranthes romanzoviana._ S. W. Ireland (North America).
+
+ 15. _Sisyrinchium angustifolium._ W. Ireland (North America, Arctic and
+ Temp.).
+
+ 16. _Potamogeton lonchites._ Ireland, Mr. Arthur Bennett informs me
+ that this is certainly not British or European, but may possibly be
+ identical with _P. fluitans_ _var._ _Americanus_ of the U. States.
+
+ 17. _Potamogeton kirkii_ (_natans_ sub.-sp.). W. Ireland. (Arctic
+ Europe?)
+
+ 18. _Eriocaulon septangulare._ W. Ireland, Skye, Hebrides (North
+ America).
+
+ 19. _Carex buxbaumii._ N. E. Ireland, on an island in Lough Neagh
+ (Arctic and Alpine Europe, North America).
+
+ 20. _Deyeuxia neglecta_ (_var._ _Hookeri_). On the shores and islands
+ of Lough Neagh. (And in Germany, Arctic Europe, and North America.)
+
+We find here nine south-west European species which probably had a wider
+range in mild preglacial times, and have been preserved in the south and
+west of Ireland owing to its milder climate. It must be remembered that
+during the height of the glacial epoch Ireland was continental, so that
+these plants may have followed the retreating ice to their present stations
+and survived the subsequent depression. This seems more probable than that
+so many species should have reached Ireland for the first time during the
+last union with the continent subsequent to the glacial epoch. The Arctic,
+Alpine, and American plants may all be examples of species which once had a
+wider range, and which, owing to the more favourable conditions, have
+continued to exist in Ireland while becoming extinct in the adjacent parts
+of Britain and Western Europe.
+
+As contrasted with the extreme scarcity of peculiar species among the
+flowering plants, it is the more interesting and unexpected to find a
+considerable number of peculiar mosses and Hepaticæ, some of which present
+us with phenomena of distribution of a very remarkable character. For the
+following lists and the information as to the distribution of the genera
+and species I am indebted to Mr. William Mitten, one of the first
+authorities on these beautiful little plants. That of the mosses has been
+corrected for this edition by Dr. R. Braithwaite, and several species of
+hepaticæ have been added by Mr. Mitten. {366}
+
+LIST OF THE SPECIES OF MOSSES AND HEPATICÆ WHICH ARE PECULIAR TO THE
+BRITISH ISLES (OR NOT FOUND IN EUROPE).
+
+(_Those belonging to non-European genera in Italics._)
+
+MOSSES.
+
+ 1. Systegium Mittenii South England.
+ 2. Campylopus Shawii North Britain.
+ 3. ,, setifolius Ireland, Wales, and Hebrides.
+ 4. Seligeria calcicola South England.
+ 5. Pottia viridifolia South England.
+ 6. Leptodontium recurvifolium Ireland and Scotland.
+ 7. Tortula Hybernica Ireland.
+ 8. _Streptopogon gemmascens_ Sussex.
+ 9. Bryum barbatum Scotland.
+ 10. _Bartramidula Wilsoni_ Ireland, Wales, and Scotland.
+ 11. _Daltonia splachnoides_ Ireland, Antilles, and Mexico.
+ 12. _Hookeria laetevirens_ Ireland, Cornwall, and Madeira.
+ 13. Hypnum micans Ireland.
+ 14. Myurium Hebridarium Hebrides and Atlantic Islands.
+ 15. Hedwigia ciliata _var._ striata Wales and Scotland.
+
+HEPATICÆ.
+
+ 1. Frullania germana Ireland.
+ 2. ,, Hutchinsiæ Ireland, Scotland, Wales, Devon,
+ Tropical regions.
+ 3. Lejeunia flava Ireland, Atlantic Islands, S. America,
+ Africa, &c.
+ 4. ,, microscopica Ireland, Wales, Cumberland, Madeira.
+ 5. ,, Holtii Ireland (Killarney).
+ 6. ,, diversiloba Ireland (Killarney), Mexico?
+ 7. ,, patens Ireland.
+ 8. Radula tenax Ireland.
+ 9. ,, Holtii Ireland.
+ 10. ,, voluta Ireland, Wales, Cumberland, Mexico?
+ 11. ,, Carringtonii Ireland.
+ 12. Lepidozia Pearsoni Wales.
+ 13. Adilocolia decipiens Ireland, Wales, Africa, and S. America.
+ 14. Cephalozia aeraria Wales.
+ 15. Lophocolia spicata Ireland, Cornwall, Anglesea.
+ 16. Martinellia nimbosa Ireland (Brandon Mountain).
+ 17. Plagiochila spinulosa Wales, Ireland, and Scotland, Atlantic
+ Islands.
+ 18. ,, ambagiosa Ireland, India.
+ 19. Jamesoniella Carringtonii Scotland.
+ 20. Gymnocolea Nevicensis Scotland.
+ 21. Jungermannia Doniana Scotland.
+ 22. Cesia crenulata Ireland, Wales.
+ 23. Chasmatocolea cuneifolia Ireland.
+ 24. Aerobolbus Wilsoni Ireland, S. America, New Zealand.
+ 25. Petalophyllum Ralfsii Ireland, Cornwall, Devon.
+
+{367}
+
+Many of the above are minute or obscure plants, and are closely allied to
+other European species with which they may have been confounded. We cannot
+therefore lay any stress on these individually as being absent from the
+continent of Europe so much of which is imperfectly explored, though it is
+probable that several of them are really confined to Britain. But there are
+a few--indicated by italics--which are in a very different category; for
+they belong to genera which are altogether unknown in any other part of
+Europe, and their nearest allies are to be found in the tropics or in the
+southern hemisphere. The four non-European genera of mosses to which we
+refer all have their maximum of development in the Andes, while the three
+non-European Hepaticæ appear to have their maximum in the temperate regions
+of the southern hemisphere. Mr. Mitten has kindly furnished me with the
+following particulars of the distribution of these genera:--
+
+ BARTRAMIDULA. Asia, Africa, S. America and Australia, but not Europe or
+ N. America.
+
+ STREPTOPOGON is a comparatively small genus, with seven species in the
+ Andes, one in the Himalayas, and three in the south temperate zone,
+ besides our English species.
+
+ DALTONIA is a large genus of inconspicuous mosses, having seventeen
+ species in the Andes, two in Brazil, two in Mexico, one in the
+ Galapagos, six in India and Ceylon, five in Java, two in Africa, and
+ three in the Antarctic Islands, and one in Ireland.
+
+ HOOKERIA (restricting that term to the species referable to
+ Cyclodictyon) is still a large genus of handsome and remarkable mosses,
+ having twenty-six species in the Andes, eleven in Brazil, eight in the
+ Antilles, one in Mexico, two in the Pacific Islands, one in New
+ Zealand, one in Java, one in India, and five in Africa--besides our
+ British species, which is found also in Madeira and the Azores but in
+ no part of Europe proper.
+
+These last two are very remarkable cases of distribution, since Mr. Mitten
+assures me that the plants are so markedly different from all other mosses
+that they would scarcely be overlooked in Europe.
+
+The distribution of the non-European genera of Hepaticæ is as follows:--
+
+ CHASMATOCOLIA. South America and Ireland.
+
+ ACROBOLBUS. A small genus found only in New Zealand and the adjacent
+ islands, besides Ireland.
+
+ {368} PETALOPHYLLUM. A small genus confined to Australia and New
+ Zealand in the southern hemisphere, Algeria, and Ireland in the
+ northern. We have also one of the Hepaticæ--_Mastigophora
+ Woodsii_--found in Ireland and the Himalayas, but unknown in any part
+ of continental Europe. The genus is most developed in New Zealand.
+
+These are certainly very interesting facts, but they are by no means so
+exceptional in this group of plants as to throw any doubt upon their
+accuracy. The Atlantic islands present very similar phenomena in the
+_Rhamphidium purpuratum_, whose nearest allies are in the West Indies and
+South America; and in three species of Sciaromium, whose only allies are in
+New Zealand, Tasmania, and the Andes of Bogota. An analogous and equally
+curious fact is the occurrence in the Drontheim mountains in Central
+Norway, of a little group of four or five peculiar species of mosses of the
+genus Mnium, which are found nowhere else; although the genus extends over
+Europe, India, and the southern hemisphere, but always represented by a
+very few wide-ranging species except in this one mountain group![85]
+
+Such facts show us the wonderful delicacy of the balance of conditions
+which determine the existence of particular species in any locality. The
+spores of mosses and Hepaticæ are so minute that they must be continually
+carried through the air to great distances, and we can hardly doubt that,
+so far as its powers of diffusion are concerned, any species which fruits
+freely might soon spread itself over the whole world. That they do not do
+so must depend on peculiarities of habit and constitution, which fit the
+different species for restricted stations and special climatic conditions;
+and according as the adaptation is more general, or the degree of
+specialisation extreme, species will have wide or restricted ranges.
+Although their fossil remains have been rarely detected, we can hardly
+doubt that mosses have as high an antiquity as ferns or Lycopods; and
+coupling this antiquity with their great powers of dispersal we may
+understand how many of the genera have come to occupy a number of detached
+areas scattered over the whole earth, but {369} always such as afford the
+peculiar conditions of climate and soil best suited to them. The repeated
+changes of temperature and other climatic conditions, which, as we have
+seen, occurred through all the later geological epochs, combined with those
+slower changes caused by geographical mutations, must have greatly affected
+the distribution of such ubiquitous yet delicately organised plants as
+mosses. Throughout countless ages they must have been in a constant state
+of comparatively rapid migration, driven to and fro by every physical and
+organic change, often subject to modification of structure or habit, but
+always seizing upon every available spot in which they could even
+temporarily maintain themselves.[86]
+
+Here then we have a group in which there is no question of the means of
+dispersal; and where the difficulties that present themselves are not how
+the species reached the remote localities in which they are now found, but
+rather why they have not established themselves in {370} many other
+stations which, so far as we can judge, seem equally suitable to them. Yet
+it is a curious fact, that the phenomena of distribution actually presented
+by this group do not essentially differ from those presented by the higher
+flowering plants which have apparently far less diffusive power, as we
+shall find when we come to treat of the floras of oceanic islands; and we
+believe that the explanation of this is, that the life of _species_, and
+especially of _genera_, is often so prolonged as to extend over whole
+cycles of such terrestrial mutations as we have just referred to; and that
+thus the majority of plants are afforded means of dispersal which are
+usually sufficient to carry them into all suitable localities on the globe.
+Hence it follows that their actual existence in such localities depends
+mainly upon vigour of constitution and adaptation to conditions just as it
+does in the case of the lower and more rapidly diffused groups, and only
+partially on superior facilities for diffusion. This important principle
+will be used further on to afford a solution of some of the most difficult
+problems in the distribution of plant life.[87]
+
+_Concluding Remarks on the Peculiarities of the British Fauna and
+Flora._--The facts, now I believe for the first time brought together,
+respecting the peculiarities of the British fauna and flora, are sufficient
+to show that there is considerable scope for the study of geographical
+distribution even in so apparently unpromising a field as one of the most
+recent of continental islands. Looking at the general bearing of these
+facts, they prove, that the idea so generally entertained as to the
+biological identity of the British Isles with the adjacent continent is not
+altogether correct. Among birds we have undoubted peculiarities in at least
+three instances; peculiar fishes are much more numerous, and in this case
+the fact that the Irish species {371} are almost all different from the
+British, and those of the Orkneys distinct from those of Scotland, renders
+it almost certain that the great majority of the fifteen peculiar British
+fishes are really peculiar and will never be found on the European
+Continent. The mosses and Hepaticæ also have been sufficiently collected in
+Europe to render it pretty certain that the more remarkable of the peculiar
+British forms are not found there; why therefore, it may be well asked,
+should there not be a proportionate number of peculiar British insects? It
+is true that numerous species have been first discovered in Britain, and,
+subsequently, on the continent; but we have many species which have been
+known for twenty, thirty, or forty years, some of which are not rare with
+us, and yet have never been found on the continent. We have also the
+curious fact of our outlying islands, such as the Shetland Isles, the Isle
+of Man, and the little Lundy Island, possessing each some peculiar forms
+which, _certainly_, do not exist on our principal island which has been so
+very thoroughly worked. Analogy, therefore, would lead us to conclude that
+many other species or varieties would exist on our islands and not on the
+continent; and when we find that a very large number (150) in three orders
+only, are so recorded, we may I think be sure that some considerable
+portion of these (though how many we cannot say) are really endemic British
+species.
+
+The general laws of distribution also lead us to expect such phenomena.
+Very rare and very local species are such as are becoming extinct; and it
+is among insects, which are so excessively varied and abundant, which
+present so many isolated forms, and which, even on continents, afford
+numerous examples of very rare species confined to restricted areas, that
+we should have the best chance of meeting with every degree of rarity down
+to the point of almost complete extinction. But we know that in all parts
+of the world islands are the refuge of species or groups which have become
+extinct elsewhere; and it is therefore in the highest degree probable that
+some species which have ceased to exist on the continent should be
+preserved in some part or other of our islands, especially {372} as these
+present favourable climatic conditions such as do not exist elsewhere.
+
+There is therefore a considerable amount of harmony in the various facts
+adduced in this chapter, as well as a complete accordance with what the
+laws of distribution in islands would lead us to expect. In proportion to
+the species of birds and fresh-water fishes, the number of insect-forms is
+enormously great, so that the numerous species or varieties here recorded
+as not yet known on the continent are not to be wondered at; while it
+would, I think, be almost an anomaly if, with peculiar birds and fishes
+there were _not_ a fair proportion of peculiar insects. Our entomologists
+should, therefore, give up the assumption, that all our insects do exist on
+the continent, and will some time or other be found there, as not in
+accordance either with the evidence or the probabilities of the case; and
+when this is done, and the interesting peculiarities of some of our smaller
+islands are remembered, the study of our native animals and plants, in
+relation to those of other countries, will acquire a new interest. The
+British Isles are said to consist of more than a thousand islands and
+islets. How many of these have ever been searched for insects? With the
+case of Lundy Island before us, who shall say that there is not yet scope
+for extensive and interesting investigations into the British fauna and
+flora?
+
+ * * * * *
+
+
+{373}
+
+CHAPTER XVII
+
+BORNEO AND JAVA
+
+ Position and Physical Features of Borneo--Zoological Features of
+ Borneo: Mammalia--Birds--The Affinities of the Bornean Fauna--Java, its
+ Position and Physical Features--General Character of the Fauna of
+ Java--Differences Between the Fauna of Java and that of the other Malay
+ Islands--Special Relations of the Javan Fauna to that of the Asiatic
+ Continent--Past Geographical Changes of Java and Borneo--The Philippine
+ Islands--Concluding Remarks on the Malay Islands.
+
+As a representative of recent continental islands situated in the tropics,
+we will take Borneo, since, although perhaps not much more ancient than
+Great Britain, it presents a considerable amount of speciality; and, in its
+relations to the surrounding islands and the Asiatic continent, offers us
+some problems of great interest and considerable difficulty.
+
+The accompanying map shows that Borneo is situated on the eastern side of a
+submarine bank of enormous extent, being about 1,200 miles from north to
+south, and 1,500 from east to west, and embracing Java, Sumatra, and the
+Malay Peninsula. This vast area is all included within the 100 fathom line,
+but by far the larger part of it--from the Gulf of Siam to the Java Sea--is
+under fifty fathoms, or about the same depth as the sea that separates our
+own island from the continent. The distance from Borneo to the southern
+extremity of the Malay Peninsula is about 350 miles, and it is nearly as
+far from Sumatra and Java, while it is more than 600 miles from the Siamese
+Peninsula, opposite to which its long northern coast extends. There is, I
+believe, nowhere else upon the globe, an island so far from a continent,
+yet separated from it by so shallow a sea. Recent changes of sea and land
+must have occurred here on a grand scale, and this adds to the interest
+attaching to the study of this large island.
+
+{374}
+
+[Illustration: MAP OF BORNEO AND JAVA, SHOWING THE GREAT SUBMARINE BANK OF
+SOUTH-EASTERN ASIA.]
+
+ The light tint shows a less depth than 100 fathoms.
+ The figures show the depth of the sea in fathoms.
+
+{375} The internal geography of Borneo is somewhat peculiar. A large
+portion of its surface is lowland, consisting of great alluvial valleys
+which penetrate far into the interior; while the mountains except in the
+north, are of no great elevation, and there are no extensive plateaux. A
+subsidence of 500 feet would allow the sea to fill the great valleys of the
+Pontianak, Banjarmassing, and Coti rivers, almost to the centre of the
+island, greatly reducing its extent, and causing it to resemble in form the
+island of Celebes to the east of it.
+
+In geological structure Borneo is thoroughly continental, possessing
+formations of all ages, with basalt and crystalline rocks, but no recent
+volcanoes. It possesses vast beds of coal of Tertiary age; and these, no
+less than the great extent of alluvial deposits in its valleys, indicate
+great changes of level in recent geological times.
+
+Having thus briefly indicated those physical features of Borneo which are
+necessary for our inquiry, let us turn to the organic world.
+
+Neither as regards this great island nor those which surround it, have we
+the amount of detailed information in a convenient form that is required
+for a full elucidation of its past history. We have, however, a tolerable
+acquaintance with the two higher groups--mammalia and birds, both of Borneo
+and of all the surrounding countries, and to these alone will it be
+necessary to refer in any detail. The most convenient course, and that
+which will make the subject easiest for the reader, will be to give, first,
+a connected sketch of what is known of the zoology of Borneo itself, with
+the main conclusions to which they point; and then to discuss the mutual
+relations of some of {376} the adjacent islands, and the series of
+geographical changes that seem required to explain them.
+
+ZOOLOGICAL FEATURES OF BORNEO.
+
+_Mammalia._--Nearly a hundred and forty species of mammalia have been
+discovered in Borneo, and of these more than three-fourths are identical
+with those of the surrounding countries, and more than one half with those
+of the continent. Among these are two lemurs, nine civets, five cats, five
+deer, the tapir, the elephant, the rhinoceros, and many squirrels, an
+assemblage which could certainly only have reached the country by land. The
+following species of mammalia are supposed to be peculiar to Borneo:--
+
+ QUADRUMANA.
+ 1. Simia morio. A small orangutan
+ with large incisor teeth.
+ 2. Hylobates mulleri.
+ 3. Nasalis larvatus.
+ 4. Semnopithecus rubicundus.
+ 5. " chrysomelas.
+ 6. " frontatus.
+ 7. " hosei. (Thomas.) Kini Balu.
+
+ CARNIVORA.
+ 8. Herpestes semitorquatus.
+ 9. Felis badia.
+
+ UNGULATA.
+ 10. Sus barbatus.
+
+ RODENTIA.
+ 11. Pteromys phæomelas.
+ 12. Sciurus jentinki. (Th.) Kini Balu.
+ 13. Sciurus whiteheadi. (Th.) Kini Balu.
+ 14. " everetti.
+ 15. Rheithrosciurus macrotis.
+ 16. Hystrix crassispinis.
+ 17. Trichys guentheri.
+ 18. Mus infraluteus. (Th.) Kini Balu.
+ 19. " alticola. (Th.) Kini Balu.
+
+ INSECTIVORA.
+ 20. Tupaia splendidula.
+ 21. " minor.
+ 22. " dorsalis.
+ 23. Dendrogale murina.
+
+ CHIROPTERA.
+ 24. Vesperugo stenopterus.
+ 25. " doriæ
+ 26. Cynopterus brachyotus.
+ 27. " lucasii.
+ 28. " spadiceus.
+ 29. Hipposideros doriæ.
+
+Of the twenty-nine peculiar species here enumerated it is possible that a
+few may be found to be identical with those of Malacca or Sumatra; but
+there are also four peculiar genera which are less likely to be discovered
+elsewhere. These are Nasalis, the remarkable long-nosed monkey;
+Rheithrosciurus, a peculiar form of squirrel; and Trichys, a tailless
+porcupine. These peculiar forms do not, however, imply that the separation
+of the island from the continent is of very ancient date, for the country
+is so vast and {377} so much of the once connecting land is covered with
+water, that the amount of speciality is hardly, if at all, greater than
+occurs in many continental areas of equal extent and remoteness. This will
+be more evident if we consider that Borneo is as large as the Indo-Chinese
+Peninsula, or as the Indian Peninsula south of Bombay, and if either of
+these countries were separated from the continent by the submergence of the
+whole area north of them as far as the Himalayas, they would be found to
+contain quite as many peculiar genera and species as Borneo actually does
+now. A more decisive test of the lapse of time since the separation took
+place is to be found in the presence of a number of representative species
+closely allied to those of the surrounding countries, such as the tailed
+monkeys and the numerous squirrels. These relationships, however, are best
+seen among the birds, which have been more thoroughly collected and more
+carefully studied than the mammalia.
+
+_Birds._--About 580 species of birds are now known to inhabit Borneo, of
+which 420 species are land-birds.[88] One hundred and eight species are
+supposed to be peculiar to the island, and of these one half have been
+noted, either by Count Salvadori or Mr. Everett, as being either
+representative species of, or closely allied to birds inhabiting other
+islands or countries. The majority of these are, as might be expected,
+allied to species inhabiting the surrounding countries, especially Sumatra,
+the Malay Peninsula, or Java, a smaller number having their representative
+forms in the Philippine Islands or Celebes. But there is another group of
+eight species whose nearest allies are found in such remote lands as
+Ceylon, North India, Burma, or China. These last have been indicated in the
+following list by a double star (**) while those which are representative
+of forms found in the immediately surrounding area, and are in many cases
+very slightly differentiated from their allies, are indicated by a single
+star (*). {378}
+
+LIST OF BIRDS WHICH ARE SUPPOSED TO BE PECULIAR TO BORNEO.
+
+ TURDIDÆ (Thrushes).
+
+ 1. **Cettia oreophila.
+ 2. *Merula seebohmi.
+ 3. **Geocichla aurata.
+ 4. **Myiophoneus borneensis.
+ 5. Brachypteryx erythrogyna.
+ 6. Copsychus niger.
+ 7. *Cittocincla suavis.
+ 8. * ,, stricklandi.
+ 9. *Henicurus borneensis.
+ 10. *Phyllergates cinereicollis.
+ 11. Burnesia superciliaris.
+
+ TIMELIIDÆ (Babbling Thrushes).
+
+ 12. *Garrulax schistochlamys.
+ 13. Rhinocichla treacheri.
+ 14. Allocotops calvus.
+ 15. **Stachyris borneensis.
+ 16. Cyanoderma bicolor.
+ 17. Chlorocharis æmiliæ.
+ 18. Androphilus accentor.
+ 19. Malacopterum cinereocapillum.
+ 20. **Staphidia everetti.
+ 21. *Herporius brunnescens.
+ 22. *Mixornis borneensis.
+ 23. * ,, montana.
+ 24. *Turdinus canicapillus.
+ 25. ,, atrigularis.
+ 26. *Drymocataphus capistratoides.
+ 27. Ptilophaga rufiventris.
+ 28. ,, leucogrammica.
+ 29. *Corythocichla crassa.
+ 30. *Turdinulus exsul.
+ 31. Orinthocichla whiteheadi.
+
+ BRACHYPODIDÆ (Bulbuls).
+
+ 32. *Hemixus connectens.
+ 33. Criniger diardi.
+ 34. * ,, ruficrissus.
+ 35. Tricophoropsis typus.
+ 36. Oreostictes leucops.
+ 37. Rubigula montis.
+ 38. * ,, paroticalis.
+ 39. Chloropsis kinabaluensis.
+ 40. * ,, irridinucha.
+
+ ORIOLIDÆ (Orioles).
+
+ 41. Oriolus consobrinus.
+ 42. *Oriolus vulneratus.
+
+ PARIDÆ (Tits).
+
+ 43. Parus sarawakensis.
+ 44. *Dendrophila corallipes.
+
+ LANIIDÆ (Shrikes).
+
+ 45. Pityriasis gymnocephala.
+ 46. *Hyloterpe hypoxantha.
+
+ DICRURIDÆ (Drongo-shrikes).
+
+ 47. *Chibia borneensis.
+
+ CAMPOPHAGIDÆ (Caterpillar-catchers).
+
+ 48. Chlamodychæra jeffreyi.
+ 49. *Artamides normani.
+ 50. Pericrocotus cinereigula.
+
+ MUSCICAPIDÆ (Flycatchers).
+
+ 51. **Hemichelidon cinereiceps.
+ 52. *Rhinomyias gularis.
+ 53. * ,, ruficrissa.
+ 54. Cryptolopha schwaneri.
+ 55. ,, montis.
+ 56. *Stoparola cerviniventris.
+ 57. Siphia coeruleata.
+ 58. ,, beccariana.
+ 59. ,, clopurensis.
+ 60. ,, obscura.
+ 61. ,, everetti.
+ 62. ,, nigrogularis.
+
+ NECTARINEIDÆ (Sun-birds).
+
+ 63. Arachnothera juliæ.
+
+ {379}
+ DICÆIDÆ (Flower-peckers).
+
+ 64. *Diceum monticolum.
+ 65. * ,, pryeri.
+ 66. *Prionochilus xanthopygius.
+ 67. **Prionochilus everetti.
+ 68. *Zosterops clara.
+
+ PLOCEIDÆ (Weavers).
+
+ 69. Chlorura borneensis.
+ 70. Munia fuscans.
+
+ CORVIDÆ (Crows).
+
+ 71. *Dendrocitta cinerascens.
+ 72. Cissa jeffreyi.
+ 73. *Platysmurus aterrimus.
+
+ PITTIDÆ (Ground Thrushes).
+
+ 74. Pitta bertæ.
+ 75. ,, arcuata.
+ 76. ,, baudi.
+ 77. *Pitta usheri.
+ 78. * ,, granatina.
+ 79. * ,, schwaneri.
+
+ EURYLÆMIDÆ (Gapers).
+
+ 80. Calyptomena whiteheadi.
+
+ CYPSELIDÆ (Swifts).
+
+ 81. Cypselus lowi.
+
+ PODARGIDÆ (Frogmouths).
+
+ 82. *Batrachostomus adspersus.
+
+ CAPRIMULGIDAE (Goatsuckers).
+
+ 83. Caprimulgus borneensis.
+ 84. Caprimulgus concretus.
+
+ PICIDÆ (Woodpeckers).
+
+ 85. *Jyngipicus aurantiiventris.
+ 86. ,, picatus.
+ 87. *Micropternus badiosus.
+ 88. Sasia everetti.
+
+ ALCEDINIDÆ (Kingfishers).
+
+ 89. *Pelargopsis leucocephala.
+ 90. *Carcineutes melanops.
+
+ TROGONIDÆ (Trogons).
+
+ 91. Harpactes whiteheadi.
+
+ CUCULIDÆ (Cuckoos).
+
+ 92. *Rhopodytes borneensis.
+
+ CAPITONIDÆ (Barbets).
+
+ 93. Cyanops pulcherrimus.
+ 94. ,, monticulus.
+ 95. *Megalæma chrysopsis.
+
+ BUBONIDÆ (Owls).
+
+ 96. Heteroscops luciæ.
+ 97. *Syrnium leptogrammicum.
+
+ FALCONIDÆ (Hawks, &c.).
+
+ 98. Spilornis pallidus.
+ 99. *Accipiter nigrotibialis.
+ 100. Microhierax latifrons.
+
+ PHASIANIDÆ (Pheasants).
+
+ 101. Polyplectron schliermacheri.
+ 102. Lobiophasis bulweri.
+ 103. *Argusianus grayi.
+ 104. *Euplocamus pyrronotus.
+ {380}
+
+ TETRAONIDÆ (Grouse, &c.).
+
+ 105. Bambusicola hyperythra.
+ 106. ,, erythrophrys.
+ 107. Hæmatortyx sanguiniceps.
+
+ RALLIDÆ (Rails).
+
+ 108. Rallina rufigenys.
+
+Representative forms of the same character as those noted above are found
+in all extensive continental areas, but they are rarely so numerous. Thus,
+in Mr. Elwes' paper on the "Distribution of Asiatic Birds," he states that
+12.5 per cent. of the land birds of Burmah and Tenasserim are peculiar
+species, whereas we find that in Borneo they are about 25 per cent., and
+the difference may fairly be imputed to the greater proportion of slightly
+modified representative species due to a period of complete isolation. Of
+peculiar genera, the Indo-Chinese Peninsula has one--Ampeliceps, a
+remarkable yellow-crowned starling, with bare pink-coloured orbits; while
+two others, Temnurus and Crypsirhina--singular birds allied to the
+jays--are found in no other part of the Asiatic continent though they occur
+in some of the Malay Islands. Borneo has seven peculiar genera of
+passeres,[89] as well as Hæmatortyx, a crested partridge; and Lobiophasis,
+a pheasant hardly distinct from Euplocamus; while two others, Pityriasis,
+an extraordinary bare-headed bird between a jay and a shrike, and
+Carpococcyx, a pheasant-like ground cuckoo formerly thought to be peculiar,
+are said to have been discovered also in Sumatra.
+
+The insects and land-shells of Borneo and of the surrounding countries are
+too imperfectly known to enable us to arrive at any accurate results with
+regard to their distribution. They agree, however, with the birds and
+mammals in their general approximation to Malayan forms, but the number of
+peculiar species is perhaps larger.
+
+The proportion here shown of less than one-fourth peculiar species of
+mammalia and fully one-fourth peculiar species of land-birds, teaches us
+that the possession of the power of flight affects but little the
+distribution of {381} land-animals, and gives us confidence in the results
+we may arrive at in those cases where we have, from whatever cause, to
+depend on a knowledge of the birds alone. And if we consider the wide range
+of certain groups of powerful flight--as the birds of prey, the swallows
+and swifts, the king-crows, and some others, we shall be forced to conclude
+that the majority of forest-birds are restricted by even narrow watery
+barriers, to an even greater extent than mammalia.
+
+_The Affinities of the Bornean Fauna._--The animals of Borneo exhibit an
+almost perfect identity in general character, and a close similarity in
+species, with those of Sumatra and the Malay Peninsula. So great is this
+resemblance that it is a question whether it might not be quite as great
+were the whole united; for the extreme points of Borneo and Sumatra are
+1,500 miles apart--as far as from Madrid to Constantinople, or from the
+Missouri valley to California. In such an extent of country we always meet
+with some local species, and representative forms, so that we hardly
+require any great lapse of time as an element in the production of the
+peculiarities we actually find. So far as the forms of life are concerned,
+Borneo, as an island, may be no older than Great Britain; for the time that
+has elapsed since the glacial epoch would be amply sufficient to produce
+such a redistribution of the species, consequent on their mutual relations
+being disturbed, as would bring the islands into their present zoological
+condition. There are, however, other facts to be considered, which seem to
+imply much greater and more complex revolutions than the recent separation
+of Borneo from Sumatra and the Malay Peninsula, and that these changes must
+have been spread over a considerable lapse of time. In order to understand
+what these changes probably were, we must give a brief sketch of the fauna
+of Java, the peculiarities of which introduce a new element into the
+question we have to discuss. {382}
+
+JAVA.
+
+The rich and beautiful island of Java, interesting alike to the politician,
+the geographer, and the naturalist, is more especially attractive to the
+student of geographical distribution, because it furnishes him with some of
+the most curious anomalies and difficult problems in a place where such
+would be least expected. As Java forms with Sumatra one almost unbroken
+line of volcanoes and volcanic mountains, interrupted only by the narrow
+Straits of Sunda, we should naturally expect a close resemblance between
+the productions of the two islands. But in point of fact there is a much
+greater difference between them than between Sumatra and Borneo, so much
+further apart, and so very unlike in physical features.[90] Java differs
+from the three great land masses--Borneo, Sumatra, and the Malay Peninsula,
+far more than either of these do from each other; and this is the first
+anomaly we encounter. But a more serious difficulty than this remains to be
+stated. Java has certain close resemblances to the Siamese Peninsula, and
+also to the Himalayas, which Borneo and Sumatra do not exhibit to so great
+a proportionate extent; and looking at the relative position of these lands
+respectively, this seems most incomprehensible. In order fully to
+appreciate the singularity and difficulty of the problem, it will be
+necessary to point out the exact nature and amount of these peculiarities
+in the fauna of Java.
+
+_General Character of the Fauna of Java._--If we were only to take account
+of the number of peculiar species in Java, and the relations of its fauna
+generally to that of the surrounding lands, we might pass it over as a less
+interesting island than Borneo or Sumatra. Its mammalia (ninety species)
+are nearly as numerous as those of Borneo, but are apparently less
+peculiar, none of the genera and only five or six of the species being
+confined to the island. In land-birds it is decidedly less rich, having
+only 300 species, of which about forty-five are peculiar, and only one
+{383} or two belong to peculiar genera; so that here again the amount of
+speciality is considerably less than in Borneo. It is only when we proceed
+to analyse the species of the Javan fauna, and trace their distribution and
+affinities, that we discover its interesting nature.
+
+_Difference Between the Fauna of Java and that of the other great Malay
+Islands._--Comparing the fauna of Java with that which may be called the
+typical Malayan fauna as exhibited in Borneo, Sumatra, and the Malay
+Peninsula, we find the following differences. No less than thirteen genera
+of mammalia, each of which is known to inhabit at least two, and generally
+all three, of the above-named Malayan countries, are totally absent from
+Java; and they include such important forms as the elephant, the tapir, and
+the Malay bear. It cannot be said that this difference depends on imperfect
+knowledge, for Java is one of the oldest European settlements in the East,
+and has been explored by a long succession of Dutch and English
+naturalists. Every part of it is thoroughly well known, and it would be
+almost as difficult to find a new mammal of any size in Europe as in Java.
+Of birds there are twenty-five genera, all typically Malayan and occurring
+at least in two, and for the most part in all three of the Malay countries,
+which are yet absent from Java. Most of these are large and conspicuous
+forms, such as jays, gapers, bee-eaters, woodpeckers, hornbills, cuckoos,
+parrots, pheasants, and partridges, as impossible to have remained
+undiscovered in Java as the large mammalia above referred to.
+
+Besides these absent _genera_ there are some curious illustrations of Javan
+isolation in the _species_; there being several cases in which the same
+species occurs in all three of the typical Malay countries, while in Java
+it is represented by an allied species. These occur chiefly among birds,
+there being no less than seven species which are common to the three great
+Malay countries but are represented in Java by distinct though closely
+allied species.
+
+From these facts it is impossible to doubt that Java has had a history of
+its own, quite distinct from that of the other portions of the Malayan
+area. {384}
+
+_Special Relations of the Javan Fauna to that of the Asiatic
+Continent._--These relations are indicated by comparatively few examples,
+but they are very clear and of great importance. Among mammalia, the genus
+Helictis is found in Java but in no other Malay country, though it inhabits
+also North India; while two species, _Rhinoceros javanicus_ and _Lepus
+kurgosa_, are natives of Indo-Chinese countries and Java, but not of
+typical Malaya. In birds there are five genera or sub-genera--Zoothera,
+Notodela, Crypsirhina, Allotrius, and Cochoa, which inhabit Java, the
+Himalayas, and Indo-China, all but the last extending south to Tenasserim,
+but none of them occurring in Malacca, Sumatra, or Borneo. There are also
+two species of birds--a trogon (_Harpactes oreskios_), and the Javanese
+peacock (_Pavo muticus_), which inhabit only Java and the Indo-Chinese
+countries, the former reaching Tenasserim and the latter Perak in the Malay
+Peninsula.
+
+Here, then, we find a series of remarkable similarities between Java and
+the Asiatic continent, quite independent of the typical Malay
+countries--Borneo, Sumatra, and the Malay Peninsula, which latter have
+evidently formed one connected land, and thus appear to preclude any
+independent union of Java and Siam.
+
+The great difficulty in explaining these facts is, that all the required
+changes of sea and land must have occurred within the period of existing
+species of mammalia. Sumatra, Borneo, and Malacca have, as we have seen, a
+great similarity as regards their species of mammals and birds, while Java,
+though it differs from them in so curious a manner, has no greater degree
+of speciality, since its species, when not Malayan, are almost all North
+Indian or Siamese.
+
+There is, however, one consideration which may help us over this
+difficulty. It seems highly probable that in the equatorial regions species
+have changed less rapidly than in the north temperate zone, on account of
+the equality and stability of the equatorial climate. We have seen, in
+Chapter X., how important an agent in producing extinction and modification
+of species must have been the repeated changes from cold to warm, and from
+warm to cold {385} conditions, with the migrations and crowding together
+that must have been their necessary consequence. But in the lowlands, near
+the equator, these changes would be very little if at all felt, and thus
+one great cause of specific modification would be wanting. Let us now see
+whether we can sketch out a series of not improbable changes which may have
+brought about the existing relations of Java and Borneo to the continent.
+
+_Past Geographical Changes of Java and Borneo._--Although Java and Sumatra
+are mainly volcanic, they are by no means wholly so. Sumatra possesses in
+its great mountain masses ancient crystalline rocks with much granite,
+while there are extensive Tertiary deposits of Eocene age, overlying which
+are numerous beds of coal now raised up many thousand feet above the
+sea.[91] The volcanoes appear to have burst through these older mountains,
+and to have partly covered them as well as great areas of the lowlands with
+the products of their eruptions. In Java either the fundamental strata were
+less extensive and less raised above the sea, or the period of volcanic
+action has been of longer duration; for here no crystalline rocks have been
+found except a few boulders of granite in the western part of the island,
+perhaps the relics of a formation destroyed by denudation or covered up by
+volcanic deposits. In the southern part of Java, however, there is an
+extensive range of low mountains, about 3,000 feet high, consisting of
+basalt with limestone, apparently of Miocene age.
+
+During this last named period, then, Java would have been at least 3,000
+feet lower than it is now, and such a depression would probably extend to
+considerable parts of Sumatra and Borneo, so as to reduce them all to a few
+small islands. At some later period a gradual elevation occurred, which
+ultimately united the whole of the islands with the continent. This may
+have continued till the glacial period of the northern hemisphere, during
+the severest part of which a few Himalayan species of birds and mammals may
+have been driven southward, and {386} have ranged over suitable portions of
+the whole area. Java then became separated by subsidence, and these species
+were imprisoned in the island; while those in the remaining part of the
+Malayan area again migrated northward when the cold had passed away from
+their former home, the equatorial forests of Borneo, Sumatra, and the Malay
+Peninsula being more especially adapted to the typical Malayan fauna which
+is there developed in rich profusion. A little later the subsidence may
+have extended farther north, isolating Borneo and Sumatra, in which a few
+other Indian or Indo-Chinese forms have been retained, but probably leaving
+the Malay Peninsula as a ridge between them as far as the islands of Banca
+and Biliton. Other slight changes of climate followed, when a further
+subsidence separated these last-named islands from the Malay Peninsula, and
+left them with two or three species which have since become slightly
+modified. We may thus explain how it is that a species is sometimes common
+to Sumatra and Borneo, while the intervening island (Banca) possesses a
+distinct form.[92]
+
+In my _Geographical Distribution of Animals_, Vol. I., p. 357, I have given
+a somewhat different hypothetical explanation of the relations of Java and
+Borneo to the continent, in which I took account of changes of land and sea
+only; but a fuller consideration of the influence of changes of climate on
+the migration of animals, has led me to the much simpler, and, I think,
+more probable, explanation above given. The amount of the relationship
+between Java and Siam, as well as of that between Java and the Himalayas,
+is too small to be well accounted for by an independent geographical
+connection in which Borneo and Sumatra did not take part. It is, at the
+same time, too distinct and indisputable to be ignored; and a change of
+climate which should drive a portion of the Himalayan fauna southward,
+leaving a few species in Java and Borneo from which they could not return
+owing to the subsequent isolation of those islands by subsidence, seems
+{387} to be a cause exactly adapted to produce the kind and amount of
+affinity between these distant countries that actually exists.
+
+THE PHILIPPINE ISLANDS.
+
+A general account of the fauna of these islands, and of their biological
+relations to the countries which form the subject of this chapter, has been
+given in my _Geographical Distribution of Animals_, Vol. I. pp. 345-349;
+but since the publication of that work considerable additions have been
+made to their fauna, having the effect of somewhat diminishing their
+isolation from the other islands. Four genera have been added to the
+terrestrial mammalia--Crocidura, Felis, Pteromys, and Mus, as well as two
+additional squirrels; while the black ape (_Cynopithecus niger_) has been
+struck out as not inhabiting the Philippines. This brings the true land
+mammalia to twenty-one species, of which fourteen are peculiar to the
+islands; but to these we must add no less than thirty-three species of bats
+of which only ten are peculiar.[93] In these estimates the Palawan {388}
+group has been omitted as these islands contain so many Bornean species
+that if included they obscure the special features of the fauna.
+
+_Birds._--The late Marquis of Tweeddale made a special study of Philippine
+birds, and in 1873 published a catalogue in the _Transactions of the
+Zoological Society_ (Vol. IX. Pt. 2, pp. 125-247). But since that date
+large collections have been made by Everett, Steere, and other travellers,
+the result of which has been to more than double the known species, and to
+render the ornithological fauna an exceedingly rich one. Many of the
+Malayan genera which were thought to be absent when the first edition of
+this work was published have since been discovered, among which are
+Phyllornis, Criniger, Diceum, Prionochilus, and Batrachostomus. But there
+still remain a large number of highly characteristic Malayan genera whose
+absence gives a distinctive feature to the Philippine bird fauna. Among
+these are Tiga and Meiglyptes, genera of woodpeckers; Phænicophaes and
+Centropus, remarkable cuckoos; the long-tailed paroquets, Palæornis; all
+the genera of Barbets except Xantholæma; the small but beautiful family
+Eurylæmidæ; many genera allied to Timalia and Ixos; the mynahs, Gracula;
+the long-tailed flycatchers, Tchitrea; the fire-backed pheasants,
+Euplocamus; the argus pheasants, the jungle-fowl, and many others.
+
+The following tabular statement will illustrate the rapid growth of our
+knowledge of the birds of the Philippines:--
+
+ |Land-birds.|Water-birds.|Total.
+ +-----------+------------+------
+ Lord Tweeddale's Catalogue (1873) | 158 | 60 | 218
+ Mr. Wardlaw Ramsay's List (1881) | 265 | 75 | 340
+ Mr. Everett's MSS. List of Additions (1891)| 370 | 102 | 472
+
+The number of peculiar species is very large, there being about 300 land
+and forty-two water birds, which are not {389} known to occur beyond the
+group. We have here, still more pronounced than in the case of Borneo, the
+remarkable fact of the true land birds presenting a larger amount of
+speciality than the land mammals; for while more than four-fifths of the
+birds are peculiar, only a little more than half the mammals are so, and if
+we exclude the bats only two-thirds.
+
+The general character of the fauna of this group of islands is evidently
+the result of their physical conditions and geological history. The
+Philippines are almost surrounded by deep sea, but are connected with
+Borneo by means of two narrow submarine banks, on the northern of which is
+situated Palawan, and on the southern the Sulu Islands. Two small groups of
+islands, the Bashees and Babuyanes, have also afforded a partial connection
+with the continent by way of Formosa. It is evident that the Philippines
+once formed part of the great Malayan extension of Asia, but that they were
+separated considerably earlier than Java; and having been since greatly
+isolated and much broken up by volcanic disturbances, their species have
+for the most part become modified into distinct local forms, representative
+species often occurring in the different islands of the group. They have
+also received a few Chinese types by the route already indicated, and a few
+Australian forms owing to their proximity to the Moluccas. Their
+comparative poverty in genera and species of the mammalia is perhaps due to
+the fact that they have been subjected to a great amount of submersion in
+recent times, greatly reducing their area and causing the extinction of a
+considerable portion of their fauna. This is not a mere hypothesis, but is
+supported by direct evidence; for I am informed by Mr. Everett, who has
+made extensive explorations in the islands, that almost everywhere are
+found large tracts of elevated coral-reefs, containing shells similar to
+those living in the adjacent seas, an indisputable proof of recent
+elevation.
+
+_Concluding Remarks on the Malay Islands._--This completes our sketch of
+the great Malay islands, the seat of the typical Malayan fauna. It has been
+shown that the peculiarities presented by the individual islands may be all
+{390} sufficiently well explained by a very simple and comparatively
+unimportant series of geographical changes, combined with a limited amount
+of change of climate towards the northern tropic. Beginning in late Miocene
+times when the deposits on the south coast of Java were upraised, we
+suppose a general elevation of the whole of the extremely shallow seas
+uniting what are now Sumatra, Java, Borneo, and the Philippines with the
+Asiatic continent, and forming that extended equatorial area in which the
+typical Malayan fauna was developed. After a long period of stability,
+giving ample time for the specialisation of so many peculiar types, the
+Philippines were first separated; then at a considerably later period Java;
+a little later Sumatra and Borneo; and finally the islands south of
+Singapore to Banca and Biliton. This one simple series of elevations and
+subsidences, combined with the changes of climate already referred to, and
+such local elevations and depressions as must undoubtedly have occurred,
+appears sufficient to have brought about the curious, and at first sight
+puzzling, relations, of the faunas of Java and the Philippines, as compared
+with those of the larger islands.
+
+We will now pass on to the consideration of two other groups which offer
+features of special interest, and which will complete our illustrative
+survey of recent continental islands.
+
+ * * * * *
+
+
+{391}
+
+CHAPTER XVIII
+
+JAPAN AND FORMOSA
+
+ Japan, its Position and Physical Features--Zoological Features of
+ Japan--Mammalia--Birds--Birds Common to Great Britain and Japan--Birds
+ Peculiar to Japan--Japan Birds Recurring in Distant
+ Areas--Formosa--Physical Features of Formosa--Animal Life of
+ Formosa--Mammalia--Land-birds Peculiar to Formosa--Formosan Birds
+ Recurring in India or Malaya--Comparison of Faunas of Hainan, Formosa,
+ and Japan--General Remarks on Recent Continental Islands.
+
+JAPAN.
+
+The Japanese Islands occupy a very similar position on the eastern shore of
+the great Euro-Asiatic continent to that of the British Islands on the
+western, except that they are about sixteen degrees further south, and
+having a greater extension in latitude enjoy a more varied as well as a
+more temperate climate. Their outline is also much more irregular and their
+mountains loftier, the volcanic peak of Fusiyama being 14,177 feet high;
+while their geological structure is very complex, their soil extremely
+fertile, and their vegetation in the highest degree varied and beautiful.
+Like our own islands, too, they are connected with the continent by a
+marine bank less than a hundred fathoms below the surface--at all events
+towards the north and south; but in the intervening space the Sea of Japan
+opens out to a width of six hundred miles, and in its central portion is
+very deep, and this may be an indication that the connection between the
+islands and the continent is of rather ancient date. At the Straits of
+Corea the distance from the main land is about 120 miles, while at the
+northern extremity of Yesso it is about 200. The island of Saghalien,
+however, separated from Yesso by a strait only twenty-five miles wide,
+forms a connection with Amoorland in about 52° N. Lat. A southern warm
+current flowing a little to the eastward of the islands, ameliorates their
+climate much in the same way as the Gulf Stream does ours, and added to
+their insular position enables them to support a more tropical vegetation
+and more varied forms of life than are found at corresponding latitudes in
+China.
+
+{392}
+
+[Illustration: MAP OF JAPAN AND FORMOSA (with depths in fathoms).
+
+Light tint, sea under 100 fathoms. Medium tint, under 1,000 fathoms. Dark
+tint, over 1,000 fathoms. The figures show the depth in fathoms.]
+
+{393}
+
+_Zoological Features of Japan._--As we might expect from the conditions
+here sketched out, Japan exhibits in all its forms of animal life a close
+general resemblance to the adjacent continent, but with a considerable
+element of specific individuality; while it also possesses some remarkable
+isolated groups. Its fauna presents indications of there having been two or
+more lines of migration at different epochs. The majority of its animals
+are related to those of the temperate or cold regions of the continent,
+either as identical or allied species; but a smaller number have a tropical
+character, and these have in several instances no allies in China but occur
+again only in Northern India or the Malay Archipelago. There is also a
+slight American element in the fauna of Japan, a relic probably of the
+period when a land communication existed between the two continents over
+what are now the shallow seas of Japan, Ochotsk, and Kamschatka. We will
+now proceed to examine the peculiarities and relations of the fauna.
+
+_Mammalia._--The mammalia of Japan at present known are forty in number;
+not very many when compared with the rich fauna of China and Manchuria, but
+containing monkeys, bears, deer, wild goats and wild boars, as well as
+foxes, badgers, moles, squirrels, and hares, so that there can be no doubt
+whatever that they imply a land connection with the continent. No complete
+account of Japan mammals has been given by any competent zoologist since
+the publication of Von Siebold's _Fauna Japonica_ in 1844, {394} but by
+collecting together most of the scattered observations since that period
+the following list has been drawn up, and will, it is hoped, be of use to
+naturalists. The species believed to be peculiar to Japan are printed in
+italics. These are very numerous, but it must be remembered that Corea and
+Manchuria (the portions of the continent opposite Japan) are comparatively
+little known, while in very few cases have the species of Japan and of the
+continent been critically compared. Where this has been done, however, the
+peculiar species established by the older naturalists have been in many
+cases found to be correct.
+
+LIST OF THE MAMMALIA OF THE JAPANESE ISLANDS.
+
+ 1. _Macacus speciosus._ A monkey with rudimentary tail and red face,
+ allied to the Barbary ape. It inhabits the island of Niphon up to 41°
+ N. Lat., and has thus the most northern range of any living monkey.
+
+ 2. _Pteropus dasymallus._ A peculiar fruit-bat, found in Kiusiu Island
+ only (Lat. 33° N.), and thus ranging further north of the equator than
+ any other species of the genus.
+
+ 3. Rhinolophus ferrum-equinum. The great horse-shoe bat, ranges from
+ Britain across Europe and temperate Asia to Japan. It is the _R.
+ nippon_ of the Fauna Japonica according to Mr. Dobson's _Monograph of
+ Asiatic Bats_.
+
+ 4. R. minor. Found also in Burma, Yunan, Java, Borneo, &c.
+
+ 5. Vesperugo pipistrellus. From Britain across Europe and Asia.
+
+ 6. V. abramus. Also in India and China.
+
+ 7. V. noctula. From Britain across Europe and Asia.
+
+ 8. V. molossus. Also in China.
+
+ 9. Vespertilio capaccinii. Philippine Islands, and Italy! This is _V.
+ macrodactylus_ of the Fauna Japonica according to Mr. Dobson.
+
+ 10. Miniopterus schreibersii. Philippines, Burma, Malay Islands. This
+ is _Vespertilio blepotis_ of the Fauna Japonica.
+
+ 11. _Talpa wogura._ Closely resembles the common mole of Europe, but
+ has six incisors instead of eight in the lower jaw.
+
+ 12. _Talpa mizura._ Günth. Allied to _T. wogura_.
+
+ 13. _Urotrichus talpoides._ A peculiar genus of moles confined to
+ Japan. An American species has been named _Urotrichus gibsii_, and Mr.
+ Lord after comparing the two says that he "can find no difference
+ whatever, either generic or specific. In shape, size, and colour, they
+ are exactly alike." But Dr. Günther (_P. Z. S._ 1880, p. 441) states
+ that _U. gibsii_ differs so much in dentition from the Japanese species
+ that it should be placed in a distinct genus, which he calls
+ Neurotrichus.
+
+ 14. Sorex myosurus. A shrew, found also in India and Malaya.
+
+ 15. _Sorex dzi-nezumi._
+
+ 16. _S. umbrinus._
+
+ 17. _S. platycephalus._ {395}
+
+ 18. Ursus arctos. var. A peculiar variety of the European brown bear
+ which inhabits also Amoorland and Kamschatka. It is the _Ursus ferox_
+ of the Fauna Japonica.
+
+ 19. _Ursus japonicus._ A peculiar species allied to the Himalayan and
+ Formosan species. Named _U. tibetanus_ in the Fauna Japonica.
+
+ 20. _Meles anakuma._ Differs from the European and Siberian badgers in
+ the form of the skull.
+
+ 21. _Mustela brachyura._ A peculiar martin found also in the Kurile
+ Islands.
+
+ 22. _Mustela melanopus._ The Japanese sable.
+
+ 23. _M. Japonica._ A peculiar martin (See _Proc. Zool. Soc._ 1865, p.
+ 104).
+
+ 24. _M. Sibericus._ Also Siberia and China. This is the _M. italsi_ of
+ the Fauna Japonica according to Dr. Gray.
+
+ 25. _Lutronectes whiteleyi._ A new genus and species of otter
+ (_P. Z. S._ 1867, p. 180). In the Fauna Japonica named _Lutra
+ vulgaris_.
+
+ 26. Enhydris marina. The sea-otter of California and Kamschatka.
+
+ 27. _Canis hodophylax._ According to Dr. Gray allied to _Cuon
+ sumatranus_ of the Malay Islands, and _C. alpinus_ of Siberia, if not
+ identical with one of them (_P. Z. S._ 1868, p. 500).
+
+ 28. _Vulpes japonica._ A peculiar fox. _Canis vulpes_ of Fauna
+ Japonica.
+
+ 29. Nyctereutes procyonoides. The racoon-dog of N. China and Amoorland.
+
+ 30. _Lepus brachyurus._ A peculiar hare.
+
+ 31. _Sciurus lis._ A peculiar squirrel.
+
+ 32. _Pteromys leucogenys._ The white-cheeked flying squirrel.
+
+ 33. _P. momoga._ Perhaps identical with a Cambojan species (_P. Z. S._
+ 1861, p. 137).
+
+ 34. _Myoxus japonicus._ A peculiar dormouse. _M. elegans_ of the Fauna
+ Japonica; _M. javanicus_, Schinz (_Synopsis Mammalium_, ii. p. 530).
+
+ 35. _Mus argenteus._ China.
+
+ 36. _Mus molossinus._
+
+ 37. _M. nezumi._
+
+ 38. _M. speciosus._
+
+ 39. _Cervus sika._ A peculiar deer allied to _C. pseudaxis_ of Formosa
+ and _C. mantchuricus_ of Northern China.
+
+ 40. _Nemorhedus crispa._ A goat-like antelope allied to _N. sumatranus_
+ of Sumatra, and _N. Swinhoei_ of Formosa.
+
+ 41. _Sus leucomystax._ A wild boar allied to _S. taeranus_ of Formosa.
+
+We thus find that no less than twenty-six out of the forty-one Japanese
+mammals are peculiar, and if we omit the aërial bats (nine in number), as
+well as the marine sea-otter, we shall have remaining only thirty strictly
+land mammalia, of which twenty-five are peculiar, or five-sixths of the
+whole. Nor does this represent all their speciality; for we have a mole
+differing in its dentition from the European mole; another superficially
+resembling but quite distinct from an American species; a peculiar genus of
+otters; and an antelope whose nearest allies are in Formosa and Sumatra.
+The importance of these facts will {396} be best understood when we have
+examined the corresponding affinities of the birds of Japan.
+
+_Birds._--Owing to the recent researches of some English residents we have
+probably a fuller knowledge of the birds than of the mammalia; yet the
+number of true land-birds ascertained to inhabit the islands either as
+residents or migrants is only 200, which is less than might be expected
+considering the highly favourable conditions of mild climate, luxuriant
+vegetation, and abundance of insect-life, and the extreme riches of the
+adjacent continent,--Mr. Swinhoe's list of the birds of China containing
+more than 400 land species, after deducting all which are peculiar to the
+adjacent islands. Only seventeen species, or about one-twelfth of the
+whole, are now considered to be peculiar to Japan proper; while seventeen
+more are peculiar to the various outlying small islands constituting the
+Bonin and Loo Choo groups. Even of these, six or seven are classed by Mr.
+Seebohm as probably sub-species or slightly modified forms of continental
+birds, so that ten only are well-marked species, undoubtedly distinct from
+those of any other country.
+
+The great majority of the birds are decidedly temperate forms identical
+with those of Northern Asia and Europe; while no less than forty of the
+species of land-birds are also found in Britain, or are such slight
+modifications of British species that the difference is only perceptible to
+a trained ornithologist. The following list of the land-birds common to
+Britain and Japan is very interesting, when we consider that these
+countries are separated by the whole extent of the European and Asiatic
+continents, or by almost exactly one-fourth of the circumference of the
+globe:--
+
+LAND BIRDS COMMON TO GREAT BRITAIN AND JAPAN.[94]
+
+(_Either Identical Species or Representative sub-species._)
+
+ 1. Goldcrest _Regulus cristatus_ sub-sp. _orientalis_.
+ 2. Marsh tit _Parus palustris_ sub-sp. _japonicus_.
+ 3. Coal tit _Parus ater_ sub-sp. _pekinensis_.
+ 4. Long-tailed tit _Acredula caudata_ (the sub-sp. _rosea_, is
+ British).
+ {397}
+ 5. Common creeper _Certhia familiaris._
+ 6. Nuthatch _Sitta europæa_ sub-sp. _amurensis._
+ 7. Carrion crow _Corvus corone._
+ 8. Nutcracker _Nucifraga caryocatactes._
+ 9. Magpie _Pica caudata._
+ 10. Pallass' grey shrike _Lanius excubitor_ sub-sp. _major._
+ 11. Waxwing _Ampelis garrulus._
+ 12. Grey wagtail _Motacilla boarula_ sub-sp. _melanope._
+ 13. Alpine Pipit _Anthus spinoletta_ sub-sp. _japonicus._
+ 14. Skylark _Alauda arvensis_ sub-sp. _japonica._
+ 15. Common hawfinch _Coccothraustes vulgaris._
+ 16. Common Crossbill _Loxia curvirostra._
+ 17. Siskin _Fringilla spinus._
+ 18. Mealy redpole ,, _linaria._
+ 19. Brambling ,, _montifringilla._
+ 20. Tree sparrow _Passer montanus._
+ 21. Reed bunting _Emberiza schoeniculus_ sub-sp.
+ _palustris._
+ 22. Rustic bunting ,, _rustica._
+ 23. Snow bunting ,, _nivalis._
+ 24. Chimney swallow _Hirundo rustica_ sub-sp. _gutturalis._
+ 25. Sand martin _Cotyle riparia._
+ 26. Great spotted woodpecker _Picus major_ sub-sp. _japonicus._
+ 27. Lesser spotted woodpecker ,, _minor._
+ 28. Wryneck _Jynx torquilla._
+ 29. Hoopoe _Upupa epops._
+ 30. Blue rock pigeon _Columba livia._
+ 31. Cuckoo _Cuculus canorus._
+ 32. Kingfisher _Alcedo ispida_ sub-sp. _bengalensis._
+ 33. Eagle owl _Bubo maximus._
+ 34. Snowy owl _Surnia nyctea._
+ 35. Long-eared owl _Strix otus._
+ 36. Short-eared owl ,, _brachyotus._
+ 37. Scops owl _Scops scops._
+ 38. Jer falcon _Falco gyrfalco._
+ 39. Peregrine falcon ,, _peregrinus._
+ 40. Hobby ,, _subbuteo._
+ 41. Merlin _Falco æsalon._
+ 42. Kestrel _Tinnunculus alaudarius_ sub-sp.
+ _japonicus._
+ 43. Osprey _Pandion haliäctus._
+ 44. Honey-buzzard _Pernis apivorus._
+ 45. White-tailed eagle _Haliäetus albicilla._
+ 46. Golden eagle _Aquila chrysäetus._
+ 47. Common buzzard _Buteo vulgaris_ sub-sp. _plumipes._
+ 48. Hen-harrier _Circus cyaneus._
+ 49. Marsh-harrier ,, _æruginosus._
+ 50. Gos-hawk _Astur palumbarius._
+ 51. Sparrow-hawk _Accipiter nisus._
+ 52. Ptarmigan _Tetrao mutus._
+ 53. Common quail _Coturnix communis._
+
+But even these fifty-three species by no means fairly represent the amount
+of _resemblance_ between Britain and {398} Japan as regards birds; for
+there are also thrushes, robins, stonechats, wrens, hedge-sparrows,
+sedge-warblers, jays, starlings, swifts, goatsuckers, and some others,
+which, though distinct _species_ from our own, have the same general
+appearance, and give a familiar aspect to the ornithology. There remains,
+however, a considerable body of Chinese and Siberian species, which link
+the islands to the neighbouring parts of the continent; and there are also
+a few which are Malayan or Himalayan rather than Chinese, and thus afford
+us an interesting problem in distribution.
+
+The seventeen species and sub-species which are altogether peculiar to
+Japan proper, are for the most part allied to birds of North China and
+Siberia, but three are decidedly tropical, and one of them--a fruit pigeon
+(_Treron sieboldi_)--has no close ally nearer than Burmah and the
+Himalayas. In the following list the affinities of the species are
+indicated wherever they have been ascertained:--
+
+LIST OF THE SPECIES OF LAND BIRDS PECULIAR TO JAPAN.
+
+ 1. _Accentor rubidus._ Nearly allied to our hedge-sparrow, and less
+ closely to the Central Asian _A. immaculatus._
+
+ (1a. _Hypsipetes amaurotis._ Migrates to the Corea, otherwise
+ peculiar.)
+
+ 2. _Zosterops japonica._ Allied to two Chinese species.
+
+ 3. _Lusciniola pryeri._
+
+ 4. _Garrulus japonicus._ Allied to the Siberian and British Jays.
+
+ 5. _Fringilla kawarahiba._ Allied to the Chinese greenfinch.
+
+ 6. _Emberiza ciopsis._ Allied to the E. Siberian bunting _E. cioides_,
+ of which it may be considered a sub-species.
+
+ 7. ,, _yessoensis._ A distinct species.
+
+ 8. ,, _personata._ A sub-species of _E. spodocephala._
+
+ 9. _Gecinus awokera._ A distinct species of green woodpecker.
+
+ 10. _Picus namiyei._ Allied to a Formosan species.
+
+ 11. _Treron sieboldi._ Allied to _T. sphenura_ of the Himalayas, and to
+ a Formosan species.
+
+ 12. _Carpophaga ianthina._ A distinct species of fruit-pigeon.
+
+ 13. _Bubo blakistoni._ Allied to a Philippine eagle-owl.
+
+ 14. _Scops semitorgues._ A distinct species.
+
+ 15. _Phasianus versicolor._ A distinct species.
+
+ 16. ,, _soemmeringi._ A distinct species.
+
+ 17. ,, _scintillaus._ A sub-species of the last.
+
+The large number of seventeen peculiar species in the outlying Bonin and
+Loo Choo Islands is an interesting feature of Japanese ornithology. The
+comparative remoteness of {399} these islands, their mild sub-tropical
+climate and luxuriant vegetation, and perhaps the absence of violent storms
+and their being situated out of the line of continental migration, seem to
+be the conditions that have favoured the specialisation of modified types
+adapted to the new environment.
+
+_Japan Birds Recurring in Distant Areas._--The most interesting feature in
+the ornithology of Japan is, undoubtedly, the presence of several species
+which indicate an alliance with such remote districts as the Himalayas, the
+Malay Islands, and Europe. Among the peculiar species, the most remarkable
+of this class are,--the fruit-pigeon of the genus Treron, entirely unknown
+in China, but reappearing in Formosa and Japan; the Hypsipetes, whose
+nearest ally is in South China at a distance of nearly 500 miles; and the
+jay (_Garrulus japonicus_), whose near ally (_G. glandarius_) inhabits
+Europe only, at a distance of 3,700 miles. But even more extraordinary are
+the following non-peculiar species:--_Spizaetus orientalis_, a crested
+eagle, inhabiting the Himalayas, Formosa, and Japan, but unknown in
+Southern or Eastern China; _Ceryle guttata_, a spotted kingfisher, almost
+confined to the Himalayas and Japan, though occurring rarely in Central
+China; and _Halcyon coromanda_, a brilliant red kingfisher inhabiting
+Northern India, the Malay Islands to Celebes, Formosa, and Japan. We have
+here an excellent illustration of the favourable conditions which islands
+afford both for species which elsewhere live further south (_Halcyon
+coromanda_), and for the preservation in isolated colonies of species which
+are verging towards extinction; for such we must consider the above-named
+eagle and kingfisher, both confined to a very limited area on the
+continent, but surviving in remote islands. Referring to our account of the
+birth, growth, and death of a species (in Chapter IV.) it can hardly be
+doubted that the _Ceryle guttata_ formerly ranged from the Himalayas to
+Japan, and has now almost died out in the intervening area owing to
+geographical and physical changes, a subject which will be better discussed
+when we have examined the interesting fauna of the island of Formosa. {400}
+
+The other orders of animals are not yet sufficiently known to enable us to
+found any accurate conclusions upon them. The main facts of their
+distribution have already been given in my _Geographical Distribution of
+Animals_ (Vol I., pp. 227-231), and they sufficiently agree with the birds
+and mammalia in showing a mixture of temperate and tropical forms with a
+considerable proportion of peculiar species. Owing to the comparatively
+easy passage from the northern extremity of Japan through the island of
+Saghalien to the mainland of Asia, a large number of temperate forms of
+insects and birds are still able to enter the country, and thus diminish
+the proportionate number of peculiar species. In the case of mammals this
+is more difficult; and the large proportion of specific difference in their
+case is a good indication of the comparatively remote epoch at which Japan
+was finally separated from the continent. How long ago this separation took
+place we cannot of course tell, but we may be sure it was much longer than
+in the case of our own islands, and therefore probably in the earlier
+portion of the Pliocene period.
+
+FORMOSA.
+
+Among recent continental islands there is probably none that surpasses in
+interest and instructiveness the Chinese island named by the Portuguese,
+Formosa, or "The Beautiful." Till quite recently it was a _terra incognita_
+to naturalists, and we owe almost all our present knowledge of it to a
+single man, the late Mr. Robert Swinhoe, who, in his official capacity as
+one of our consuls in China, visited it several times between 1856 and
+1866, besides residing on it for more than a year. During this period he
+devoted all his spare time and energy to the study of natural history, more
+especially of the two important groups, birds and mammals; and by employing
+a large staff of native collectors and hunters, he obtained a very complete
+knowledge of its fauna. In this case, too, we have the great advantage of a
+very thorough knowledge of the adjacent parts of the continent, in great
+part due to Mr. Swinhoe's own exertions during the twenty years of his
+service in {401} that country. We possess, too, the further advantage of
+having the whole of the available materials in these two classes collected
+together by Mr. Swinhoe himself after full examination and comparison of
+specimens; so that there is probably no part of the world (if we except
+Europe, North America, and British India) of whose warm-blooded vertebrates
+we possess fuller or more accurate knowledge than we do of those of the
+coast districts of China and its islands.[95]
+
+_Physical Features of Formosa._--The island of Formosa is nearly half the
+size of Ireland, being 220 miles long, and from twenty to eighty miles
+wide. It is traversed down its centre by a fine mountain range, which
+reaches an altitude of about 8,000 feet in the south and 12,000 feet in the
+northern half of the island, and whose higher slopes and valleys are
+everywhere clothed with magnificent forests. It is crossed by the line of
+the Tropic of Cancer a little south of its centre; and this position,
+combined with its lofty mountains, gives it an unusual variety of tropical
+and temperate climates. These circumstances are all highly favourable to
+the preservation and development of animal life, and from what we already
+know of its productions, it seems probable that few, if any islands of
+approximately the same size and equally removed from a continent will be
+found to equal it in the number and variety of their higher animals. The
+outline map (at page 392) shows that Formosa is connected with the mainland
+by a submerged bank, the hundred-fathom line including it along with Hainan
+to the south-west and Japan on the north-east; while the line of
+two-hundred fathoms includes also the Madjico-Sima and Loo-Choo Islands,
+and may, perhaps, mark out approximately the last great extension of the
+Asiatic continent, the submergence of which isolated these islands from the
+mainland.
+
+_Animal Life of Formosa._--We are at present acquainted {402} with 35
+species of mammalia, and 128 species of land-birds from Formosa, fourteen
+of the former and forty-three of the latter being peculiar, while the
+remainder inhabit also some part of the continent or adjacent islands. This
+proportion of peculiar species is perhaps (as regards the birds) the
+highest to be met with in any island which can be classed as both
+continental and recent, and this, in all probability, implies that the
+epoch of separation is somewhat remote. It was not, however, remote enough
+to reach back to a time when the continental fauna was very different from
+what it is now, for we find all the chief types of living Asiatic mammalia
+represented in this small island. Thus we have monkeys; insectivora;
+numerous carnivora; pigs, deer, antelopes, and cattle among ungulata;
+numerous rodents, and the edentate Manis,--a very fair representation of
+Asiatic mammals, all being of known genera, and of species either
+absolutely identical with some still living elsewhere or very closely
+allied to them. The birds exhibit analogous phenomena, with the exception
+that we have here two peculiar and very interesting genera.
+
+But besides the amount of specific and generic modification that has
+occurred, we have another indication of the lapse of time in the peculiar
+relations of a large proportion of the Formosan animals, which show that a
+great change in the distribution of Asiatic species must have taken place
+since the separation of the island from the continent. Before pointing
+these out it will be advantageous to give lists of the mammalia and
+peculiar birds of the island, as we shall have frequent occasion to refer
+to them.
+
+LIST OF THE MAMMALIA OF FORMOSA. (The peculiar species are printed in
+italics.)
+
+ 1. _Macacus cyclopis._ A rock-monkey more allied to _M. rhesus_ of
+ India than to _M. sancti-johannis_ of South China.
+ 2. _Pteropus formosus._ A fruit-bat closely allied to the Japanese
+ species. None of the genus are found in China.
+ 3. Vesperugo abramus. China.
+ 4. Vespertilio formosus. Black and orange Bat. China.
+ 5. Nyctinomus cestonii. Large-eared Bat. China, S. Europe.
+ 6. _Talpa insularis._ A blind mole of a peculiar species.
+ {403} 7. Sorex murinus. Musk Rat. China.
+ 8. Sorex sp. A shrew, undescribed.
+ 9. Erinaceus sp. A Hedgehog, undescribed.
+ 10. Ursus tibetanus. The Tibetan Bear. Himalayas and North China.
+ 11. _Helictis subaurantiaca._ The orange-tinted Tree Civet. Allied to
+ _H. nipalensis_ of the Himalayas more than to _H. moschata_ of
+ China.
+ 12. Martes flavigula, var. The yellow-necked Marten. India, China.
+ 13. Felis macroscelis. The clouded Tiger of Siam and Malaya.
+ 14. Felis viverrina. The Asiatic wild Cat. Himalayas and Malacca.
+ 15. Felis chinensis. The Chinese Tiger Cat. China.
+ 16. Viverricula malaccensis. Spotted Civet. China, India.
+ 17. Paguma larvata. Gem-faced Civet. China.
+ 18. _Sus taivanus._ Allied to the wild Pig of Japan.
+ 19. Cervulus reevesii. Reeve's Muntjac. China.
+ 20. _Cervus pseudaxis._ Formosan Spotted Deer. Allied to _C. sika_ of
+ Japan.
+ 21. _Cervus swinhoii._ Swinhoe's Rusa Deer. Allied to Indian and
+ Malayan species.
+ 22. _Nemorhedus swinhoii._ Swinhoe's Goat-antelope. Allied to the
+ species of Sumatra and Japan.
+ 23. Bos chinensis. South China wild Cow.
+ 24. Mus bandicota. The Bandicoot Rat. Perhaps introduced from India.
+ 25. Mus indicus. Indian Rat.
+ 26. _Mus coxinga._ Spinous Country-rat.
+ 27. _Mus canna._ Silken Country-rat.
+ 28. _Mus losca_. Brown Country-rat.
+ 29. Sciurus castaneoventris. Chestnut-bellied Squirrel. China and
+ Hainan.
+ 30. Sciurus m'clellandi. McClelland's Squirrel. Himalayas, China.
+ 31. _Sciuropterus kaleensis._ Small Formosan Flying Squirrel. Allied to
+ _S. alboniger_ of Nepal.
+ 32. _Pteromys grandis._ Large Red Flying Squirrel. Allied to Himalayan
+ and Bornean species. From North Formosa.
+ 33. _Pteromys pectoralis._ White-breasted Flying Squirrel. From South
+ Formosa.
+ 34. Lepus sinensis. Chinese Hare. Inhabits South China.
+ 35. Manis dalmanni. Scaly Ant-eater. China and the Himalayas.
+
+The most interesting and suggestive feature connected with these Formosan
+mammals is the identity or affinity of several of them, with Indian or
+Malayan rather than with Chinese species. We have the rock-monkey of
+Formosa allied to the rhesus monkeys of India and Burma, not to those of
+South China and Hainan. The tree civet (_Helictis subaurantiaca_), and the
+small flying squirrel (_Sciuropterus kaleensis_), are both allied to
+Himalayan species. Swinhoe's deer and goat-antelope are nearest to Malayan
+species, as are the red and white-breasted flying squirrels; while the
+fruit-bat, the wild pig, {404} and the spotted deer are all allied to
+peculiar Japanese species. The clouded tiger is a Malay species unknown in
+China, while the Asiatic wild cat is a native of the Himalayas and Malacca.
+It is clear, therefore, that before Formosa was separated from the mainland
+the above named animals or their ancestral types must have ranged over the
+intervening country as far as the Himalayas on the west, Japan on the
+north, and Borneo or the Philippines on the south; and that after that
+event occurred, the conditions were so materially changed as to lead to the
+extinction of these species in what are now the coast provinces of China,
+while they or their modified descendants continued to exist in the dense
+forests of the Himalayas and the Malay Islands, and in such detached
+islands as Formosa and Japan. We will now see what additional light is
+thrown upon this subject by an examination of the birds.
+
+LIST OF THE LAND BIRDS PECULIAR TO FORMOSA.
+
+ TURDIDÆ (Thrushes).
+
+ 1. _Turdus albiceps._ Allied to Chinese species.
+
+ SYLVIDIÆ (Warblers).
+
+ 2. _Cisticola volitans._ Allied to _C. schoenicola_ of India and
+ China.
+ 3. _Herbivox cantans._ Sub-species of _H. cantillaus_ of N. China and
+ Japan.
+ 4. _Notodela montium._ Allied to _N. leucura_ of the Himalayas; no ally
+ in China.
+
+ TIMALIIDÆ (Babblers).
+
+ 5. _Pomatorhinus musicus._ Allies in S. China and the Himalayas.
+ 6. _P. erythroenemis._ Do. do.
+ 7. _Garrulax ruficeps._ Allied to _G. albogularis_ of N. India and East
+ Thibet, not to the species of S. China (_G. sannio_).
+ 8. _Janthocincla poecilorhyncha._ Allied to _J. coerulata_ of the
+ Himalayas. None of the genus in China.
+ 9. _Trochalopteron taivanus._ Allied to a Chinese species.
+ 10. _Alcippe morrisoniana._} Near the Himalayan _A. nipalensis_.
+ 11. _A. brunnea._ } None of the genus in China.
+ 12. _Sibia auricularis._ Allied to the Himalayan _S. capistrata_. The
+ genus not known in China.
+
+ PANURIDÆ (Bearded Tits, &c.).
+
+ 13. _Suthora bulomachus._ Allied to the Chinese _S. suffusa_.
+
+ CINCLIDÆ (Dippers and Whistling Thrushes).
+
+ 14. _Myiophoneus insularis._ Allied to _M. horsfieldi_ of South India.
+ {405}
+
+ PARIDÆ (Tits).
+
+ 15. _Parus insperatus._ Sub-species of _P. monticola_ of the Himalayas
+ and East Thibet.
+ 16. _P. castaneiventris._ Allied to _P. varius_ of Japan.
+
+ LIOTRICHIDÆ (Hill Tits).
+
+ 17. _Liocichla steerii._ A peculiar genus of a specially Himalayan
+ family, quite unknown in China.
+
+ PYCNONOTIDÆ (Bulbuls).
+
+ 18. _Pycnonotus (Spizixos) cinereicapillus_. Very near _P. semitorques_
+ of China.
+ 19. _Hypsipetes nigerrimus._ Allied to _H. concolor_ of Assam, not to
+ _H. macclellandi_ of China.
+
+ ORIOLIDÆ (Orioles).
+
+ 20. _Analcipus ardens._ Allied to _A. traillii_ of the Himalayas and
+ Tenasserim.
+
+ CAMPEPHAGIDÆ (Caterpillar Shrikes).
+
+ 21. _Graucalus rex-pineti._ Closely allied to the Indian _G. macei_. No
+ ally in China.
+
+ DICRURIDÆ (King Crows).
+
+ 22. _Chaptia brauniana._ Closely allied to _C. ænea_ of Assam. No ally
+ in China.
+
+ MUSCICAPIDÆ (Flycatchers).
+
+ 23. _Cyornis vivida._ Allied to _C. rubeculoides_ of India.
+
+ CORVIDÆ (Jays and Crows).
+
+ 24. _Garrulus taivanus._ Allied to _G. sinensis_ of S. China.
+ 25. _Urocissa coerulea._ A very distinct species from its Indian and
+ Chinese allies.
+ 26. _Dendrocitta formosæ._ A sub-species of the Chinese _D. sinensis_.
+
+ PLOCEIDÆ (Weaver Finches).
+
+ 27. _Munia formosana._ Allied to _M. rubronigra_ of India and Burmah.
+
+ ALAUDIDÆ (Larks).
+
+ 28. _Alauda sala._}Allies in South China.
+ 29. _A. wattersi._}
+
+ PITTIDÆ (Pittas).
+
+ 30. _Pitta oreas._ Allied to _P. cyanoptera_ of Malaya and S. China.
+
+ PICIDÆ (Woodpeckers).
+
+ 31. _Picus insularis._ Allied to _P. leuconotus_ of Japan and Siberia.
+
+ MEGALÆMIDÆ.
+
+ 32. _Megalæma nuchalis._ Allied to _M. oortii_ of Sumatra and _M.
+ faber_ of Hainan. No allies in China.
+
+ CAPRIMULGIDÆ (Goatsuckers).
+
+ 33. _Caprimulgus stictomus._ A sub-species of _C. monticolus_ of India
+ and China.
+
+ {406}
+
+ COLUMBIDÆ (Pigeons).
+
+ 34. _Treron formosæ._ Allied to Malayan species.
+ 35. _Sphenocercus sororius._ Allied to Malay species and to _S.
+ sieboldi_ of Japan. No allies of these two birds inhabit China.
+ 36. _Chalcophaps formosana._ Allied to the Indian species which extends
+ to Tenasserim and Hainan.
+
+ TETRAONIDÆ (Grouse and Partridges).
+
+ 37. _Orcoperdix crudigularis._ A peculiar genus of partridges.
+ 38. _Bambusicola sonorivox._ Allied to the Chinese _B. thoracica_.
+ 39. _Arcoturnix rostrata._ Allied to the Chinese _A. blakistonii_.
+
+ PHASIANIDÆ (Pheasants).
+
+ 40. _Phasianus formosanus._ Allied to _P. torquatus_ of China.
+ 41. _Euplocamus swinhoii._ A very peculiar and beautiful species allied
+ to the tropical fire-backed pheasants, and to the silver pheasant of
+ North China.
+
+ STRIGIDÆ (Owls).
+
+ 42. _Athene pardalota._ Closely allied to a Chinese species.
+ 43. _Lempigius hambroekii._ Allied to a Chinese species.
+
+This list exhibits to us the marvellous fact that more than half the
+peculiar species of Formosan birds have their nearest allies in such remote
+regions as the Himalayas, South India, the Malay Islands, or Japan, rather
+than in the adjacent parts of the Asiatic continent. Fourteen species have
+Himalayan allies, and six of these belong to genera which are unknown in
+China. One has its nearest ally in the Nilgherries, and five in the Malay
+Islands; and of these six, four belong to genera which are not Chinese. Two
+have their only near allies in Japan. Perhaps more curious still are those
+cases in which, though the genus is Chinese, the nearest allied species is
+to be sought for in some remote region. Thus we have the Formosan babbler
+(_Garrulax ruficeps_) not allied to the species found in South China, but
+to one inhabiting North India and East Thibet; while the black bulbul
+(_Hypsipetes nigerrimus_), is not allied to the Chinese species but to an
+Assamese form.
+
+In the same category as the above we must place eight species not peculiar
+to Formosa, but which are Indian or Malayan rather than Chinese, so that
+they offer examples of discontinuous distribution somewhat analogous to
+what {407} we found to occur in Japan. These are enumerated in the
+following list.
+
+SPECIES OF BIRDS COMMON TO FORMOSA AND INDIA OR MALAYA, BUT NOT FOUND IN
+CHINA.
+
+1. _Siphia superciliaris._ The Rufous-breasted Flycatcher of the S. E.
+Himalayas.
+
+2. _Halcyon coromanda._ The Great Red Kingfisher of India, Malaya, and
+Japan.
+
+3. _Palumbus pulchricollis._ The Darjeeling Wood-pigeon of the S. E.
+Himalayas.
+
+4. _Turnix dussumieri._ The larger Button-quail of India.
+
+5. _Spizaetus nipalensis._ The Spotted Hawk-eagle of Nepal and Assam.
+
+6. _Lophospiza trivirgata._ The Crested Gos-hawk of the Malay Islands.
+
+7. _Bulaca newarensis._ The Brown Wood-owl of the Himalayas.
+
+8. _Strix candida._ The Grass-owl of India and Malaya.
+
+The most interesting of the above are the pigeon and the flycatcher, both
+of which are, so far as yet known, strictly confined to the Himalayan
+mountains and Formosa. They thus afford examples of discontinuous specific
+distribution exactly parallel to that of the great spotted kingfisher,
+already referred to as found only in the Himalayas and Japan.
+
+_Comparison of the Faunas of Hainan, Formosa, and Japan._--The island of
+Hainan on the extreme south of China, and only separated from the mainland
+by a strait fifteen miles wide, appears to have considerable similarity to
+Formosa, inasmuch as it possesses seventeen peculiar land-birds (out of 130
+obtained by Mr. Swinhoe), two of which are close allies of Formosan
+species, while two others are identical. We also find four species whose
+nearest allies are in the Himalayas. Our knowledge of this island and of
+the adjacent coast of China is not yet sufficient to enable us to form an
+accurate judgment of its relations, but it seems probable that it was
+separated from the continent at, approximately, the same epoch as Formosa
+and Japan, and that the special features of each of these islands are
+mainly due to their geographical position. Formosa, being more completely
+isolated than either of the others, possesses a larger proportion of
+peculiar species of birds, while its tropical situation and lofty mountain
+ranges {408} have enabled it to preserve an unusual number of Himalayan and
+Malayan forms. Japan, almost equally isolated towards the south, and having
+a much greater variety of climate as well as a much larger area, possesses
+about an equal number of mammalia with Formosa, and an even larger
+proportion of peculiar species. Its birds, however, though more numerous
+are less peculiar; and this is probably due to the large number of species
+which migrate northwards in summer, and find it easy to enter Japan through
+the Kurile Isles or Saghalien.[96] Japan too, is largely peopled by those
+northern types which have an unusually wide range, and which, being almost
+all migratory, are accustomed to cross over seas of moderate extent. The
+regular or occasional influx of these species prevents the formation of
+special insular races, such as are almost always produced when a portion of
+the population of a species remains for a considerable time completely
+isolated. We thus have explained the curious fact, that while the mammalia
+of the two islands are almost equally peculiar, (those of Japan being most
+so in the present state of our knowledge), the birds of Formosa show a far
+greater number of peculiar species than those of Japan.
+
+_General Remarks on Recent Continental Islands._--We have now briefly
+sketched the zoological peculiarities of an illustrative series of recent
+continental islands, commencing with one of the most recent--Great
+Britain--in which the process of formation of peculiar species has only
+just commenced, and terminating with Formosa, probably one of the most
+ancient of the series, and which accordingly presents us with a very large
+proportion of peculiar species, not only in its mammalia, which have no
+means of crossing the wide strait which separates it from the mainland, but
+also in its birds, many of which are quite able to cross over.
+
+Here, too, we obtain a glimpse of the way in which {409} species die out
+and are replaced by others, which quite agrees with what the theory of
+evolution assures us must have occurred. On a continent, the process of
+extinction will generally take effect on the circumference of the area of
+distribution, because it is there that the species comes into contact with
+such adverse conditions or competing forms as prevent it from advancing
+further. A very slight change will evidently turn the scale and cause the
+species to contract its range, and this usually goes on till it is reduced
+to a very restricted area, and finally becomes extinct. It may conceivably
+happen (and almost certainly has sometimes happened) that the process of
+restriction of range by adverse conditions may act in one direction only,
+and over a limited district, so as ultimately to divide the specific area
+into two separated parts, in each of which a portion of the species will
+continue to maintain itself. We have seen that there is reason to believe
+that this has occurred in a very few cases both in North America and in
+Northern Asia. (_See_ pp. 65-68.) But the same thing has certainly occurred
+in a considerable number of cases, only it has resulted in the divided
+areas being occupied by _representative forms_ instead of by the very same
+species. The cause of this is very easy to understand. We have already
+shown that there is a large amount of local variation in a considerable
+number of species, and we may be sure that were it not for the constant
+intermingling and intercrossing of the individuals inhabiting adjacent
+localities this tendency to local variation in adaptation to slightly
+different conditions, would soon form distinct races. But as soon as the
+area is divided into two portions the intercrossing is stopped, and the
+usual result is that two closely allied races, classed as representative
+species, become formed. Such pairs of allied species on the two sides of a
+continent, or in two detached areas, are very numerous; and their existence
+is only explicable on the supposition that they are descendants of a parent
+form which once occupied an area comprising that of both of them,--that
+this area then became discontinuous,--and, lastly, that, as a consequence
+of the discontinuity, the two sections of the parent species became
+segregated into distinct races or new species. {410}
+
+Now, when the division of the area leaves one portion of the species in an
+island, a similar modification of the species, either in the island or in
+the continent, occurs, resulting in closely-allied but distinct forms; and
+such forms are, as we have seen, highly characteristic of island-faunas.
+But islands also favour the occasional preservation of the unchanged
+species--a phenomenon which very rarely occurs in continents. This is
+probably due to the absence of competition in islands, so that the parent
+species there maintains itself unchanged, while the continental portion, by
+the force of that competition, is driven back to some remote mountain area,
+where it also obtains a comparative freedom from competition. Thus may be
+explained the curious fact, that the species common to Formosa and India
+are generally confined to limited areas in the Himalayas, or in other cases
+are found only in remote islands, as Japan or Hainan.
+
+The distribution and affinities of the animals of continental islands thus
+throws much light on that obscure subject--the decay and extinction of
+species; while the numerous and delicate gradations in the modification of
+the continental species, from perfect identity, through slight varieties,
+local forms, and insular races, to well-defined species and even distinct
+genera, afford an overwhelming mass of evidence in favour of the theory of
+"descent with modification."
+
+We shall now pass on to another class of islands, which, though originally
+forming parts of continents, were separated from them at very remote
+epochs. This antiquity is clearly manifested in their existing faunas,
+which present many peculiarities, and offer some most curious problems to
+the student of distribution.
+
+ * * * * *
+
+
+{411}
+
+CHAPTER XIX
+
+ANCIENT CONTINENTAL ISLANDS: THE MADAGASCAR GROUP
+
+ Remarks on Ancient Continental Islands--Physical Features of
+ Madagascar--Biological Features of
+ Madagascar--Mammalia--Reptiles--Relation of Madagascar to Africa--Early
+ History of Africa and Madagascar--Anomalies of Distribution and How to
+ Explain Them--The Birds of Madagascar as Indicating a Supposed Lemurian
+ Continent--Submerged Islands between Madagascar and India--Concluding
+ Remarks on "Lemuria"--The Mascarene Islands--The Comoro Islands--The
+ Seychelles Archipelago--Birds of the Seychelles--Reptiles and
+ Amphibia--Freshwater Fishes--Land Shells--Mauritius, Bourbon, and
+ Rodriguez--Birds--Extinct Birds and their Probable
+ Origin--Reptiles--Flora of Madagascar and the Mascarene
+ Islands--Curious Relations of Mascarene Plants--Endemic Genera of
+ Mauritius and Seychelles--Fragmentary Character of the Mascarene
+ Flora--Flora of Madagascar Allied to that of South
+ Africa--Preponderance of Ferns in the Mascarene Flora--Concluding
+ Remarks on the Madagascar Group.
+
+We have now to consider the phenomena presented by a very distinct class of
+islands--those which, although once forming part of a continent, have been
+separated from it at a remote epoch when its animal forms were very unlike
+what they are now. Such islands preserve to us the record of a by-gone
+world,--of a period when many of the higher types had not yet come into
+existence and when the distribution of others was very different from what
+prevails at the present day. The problem presented by these ancient islands
+is often complicated by the changes they themselves have undergone since
+the period of their separation. A partial subsidence will have led to the
+{412} extinction of some of the types that were originally preserved, and
+may leave the ancient fauna in a very fragmentary state; while subsequent
+elevations may have brought it so near to the continent that some
+immigration even of mammalia may have taken place. If these elevations and
+subsidences occurred several times over, though never to such an extent as
+again to unite the island with the continent, it is evident that a very
+complex result might be produced; for besides the relics of the ancient
+fauna, we might have successive immigrations from surrounding lands
+reaching down to the era of existing species. Bearing in mind these
+possible changes, we shall generally be able to arrive at a fair
+conjectural solution of the phenomena of distribution presented by these
+ancient islands.
+
+Undoubtedly the most interesting of such islands, and that which exhibits
+their chief peculiarities in the greatest perfection, is Madagascar, and we
+shall therefore enter somewhat fully into its biological and physical
+history.
+
+_Physical Features of Madagascar._--This great island is situated about 250
+miles from the east coast of Africa, and extends from 12° to 25œ° S. Lat.
+It is almost exactly 1,000 miles long, with an extreme width of 360 and an
+average width of more than 260 miles. A lofty granitic plateau, from eighty
+to 160 miles wide and from 3,000 to 5,000 feet high, occupies its central
+portion, on which rise peaks and domes of basalt and granite to a height of
+nearly 9,000 feet; and there are also numerous extinct volcanic cones and
+craters. All round the island, but especially developed on the south and
+west, are plains of a few hundred feet elevation, formed of rocks which are
+shown by their fossils to be of Jurassic age, or at all events to belong to
+somewhere near the middle portion of the Secondary period. The higher
+granitic plateau consists of bare undulating moors, while the lower
+Secondary plains are more or less wooded; and there is here also a
+continuous belt of dense forest, varying from six or eight to fifty miles
+wide, encircling the whole island, usually at about thirty miles distance
+from the coast but in the north-east coming down to the sea-shore. {413}
+
+[Illustration]
+
+{414}
+
+The sea around Madagascar, when the shallow bank on which it stands is
+passed, is generally deep. This 100-fathom bank is only from one to three
+miles wide on the east side, but on the west it is much broader, and
+stretches out opposite Mozambique to a distance of about eighty miles. The
+Mozambique Channel is rather more than 1,000 fathoms deep, but there is
+only a narrow belt of this depth opposite Mozambique, and still narrower
+where the Comoro Islands and adjacent shoals seem to form stepping-stones
+to the continent of Africa. The 1,000-fathom line includes Aldabra and the
+small Farquhar Islands to the north of Madagascar; while to the east the
+sea deepens rapidly to the 1,000-fathom line and then more slowly, a
+profound channel of 2,400 fathoms separating Madagascar from Bourbon and
+Mauritius. To the north-east of Mauritius are a series of extensive shoals
+forming four large banks less than 100 fathoms below the surface, while the
+1,000-fathom line includes them all, with an area about half that of
+Madagascar itself. A little further north is the Seychelles group, also
+standing on an extensive 1,000-fathom bank, while all round the sea is more
+than 2,000 fathoms deep.
+
+It seems probable, then, that to the north-east of Madagascar there was
+once a series of very large islands, separated from it by not very wide
+straits; while eastward across the Indian Ocean we find the Chagos and
+Maldive coral atolls, perhaps marking the position of other large islands,
+which together would form a line of communication, by comparatively easy
+stages of 400 or 500 miles each between Madagascar and India. These
+submerged islands, as shown in our map at p. 424, are of great importance
+in explaining some anomalous features in the zoology of this great island.
+
+If the rocks of Secondary age which form a belt around the island are held
+to indicate that Madagascar was once of less extent than it is now (though
+this by no means necessarily follows), we have also evidence that it has
+recently been considerably larger; for along the east coast there is an
+extensive barrier coral-reef about 350 miles in length, and varying in
+distance from the land from a quarter of a mile to three or four miles.
+This seems to indicate recent subsidence; while we have no record of raised
+coral rocks inland which would certainly mark any recent elevation, though
+fringing coral reefs surround a considerable portion of the northern,
+eastern, and south-western coasts. We may therefore conclude that during
+Tertiary times the island was usually as large as, and often probably much
+larger than, it is now. {415}
+
+[Illustration: MAP OF THE MADAGASCAR GROUP, SHOWING DEPTHS OF SEA.]
+
+In this Map the depth of the sea is shown by three tints; the lightest tint
+indicating from 0 to 100 fathoms, the medium tint from 100 to 1,000
+fathoms, the dark tint more than 1,000 fathoms.
+
+{416}
+
+_Biological Features of Madagascar._--Madagascar possesses an exceedingly
+rich and beautiful fauna and flora, rivalling in some groups most tropical
+countries of equal extent, and even when poor in species, of surpassing
+interest from the singularity, the isolation, or the beauty of its forms of
+life. In order to exhibit the full peculiarity of its natural history and
+the nature of the problems it offers to the biological student, we must
+give an outline of its more important animal forms in systematic order.
+
+_Mammalia._--Madagascar possesses no less than sixty-six species of
+mammals--a certain proof in itself that the island has once formed part of
+a continent; but the character of these animals is very extraordinary and
+altogether different from the assemblage now found in Africa or in any
+other existing continent. Africa is now most prominently characterised by
+its monkeys, apes, and baboons; by its lions, leopards, and hyænas; by its
+zebras, rhinoceroses, elephants, buffaloes, giraffes, and numerous species
+of antelopes. But no one of these animals, nor any thing like them, is
+found in Madagascar, and thus our first impression would be that it could
+never have been united with the African continent. But, as the tigers, the
+bears, the tapirs, the deer, and the numerous squirrels of Asia are equally
+absent, there seems no probability of its having been united with that
+continent. Let us then see to what groups the mammalia of Madagascar
+belong, and where we must look for their probable allies.
+
+First and most important are the lemurs, consisting of six genera and
+thirty-three species, thus comprising just half the entire mammalian
+population of the island. This group of lowly-organised and very ancient
+creatures {417} still exists scattered over a wide area; but they are
+nowhere so abundant as in the island of Madagascar. They are found from
+West Africa to India, Ceylon, and the Malay Archipelago, consisting of a
+number of isolated genera and species, which appear to maintain their
+existence by their nocturnal and arboreal habits, and by haunting dense
+forests. It can hardly be said that the African forms of lemurs are more
+nearly allied to those of Madagascar than are the Asiatic, the whole series
+appearing to be the disconnected fragments of a once more compact and
+extensive group of animals.
+
+Next, we have about a dozen species of Insectivora, consisting of one
+shrew, a group distributed over all the great continents; and five genera
+of a peculiar family, Centetidæ, which family exists nowhere else on the
+globe except in the two largest West Indian Islands, Cuba and Hayti, thus
+adding still further to our embarrassment in seeking for the original home
+of the Madagascar fauna.
+
+We then come to the Carnivora, which are represented by a peculiar cat-like
+animal, Cryptoprocta, forming a distinct family, and having no close allies
+in any part of the globe; and eight civets belonging to four peculiar
+genera. Here we first meet with some decided indications of an African
+origin; for the civet family is more abundant in this continent than in
+Asia, and some of the Madagascar genera seem to be decidedly allied to
+African groups--as, for example, Eupleres to Suricata and Crossarchus.[97]
+
+The Rodents consist only of four rats and mice of peculiar genera, one of
+which is said to be allied to an American genus; and lastly we have a
+river-hog of the African genus Potamochærus, and a small sub-fossil
+hippopotamus, both of which being semi-aquatic animals might easily have
+reached the island from Africa, by way of the Comoros, without any actual
+land connection.[98]
+
+_Reptiles of Madagascar._--Passing over the birds for the present, as not
+so clearly demonstrating {418} land-connection, let us see what indications
+are afforded by the reptiles. The large and universally distributed family
+of Colubrine snakes is represented in Madagascar, not by African or Asiatic
+genera, but by two American genera--Philodryas and Heterodon, and by
+Herpetodryas, a genus found in America and China. The other genera are all
+peculiar, and belong mostly to widespread tropical families; but two
+families--Lycodontidæ and Viperidæ, both abundant in Africa and the Eastern
+tropics--are absent. Lizards are mostly represented by peculiar genera of
+African or tropical families, but several African genera are represented by
+peculiar species, and there are also some species belonging to two American
+genera of the Iguanidæ, a family which is exclusively American; while a
+genus of geckoes, inhabiting America and Australia, also occurs in
+Madagascar.
+
+_Relation of Madagascar to Africa._--These facts taken all together are
+certainly very extraordinary, since they show in a considerable number of
+cases as much affinity with America as with Africa; while the most striking
+and characteristic groups of animals now inhabiting Africa are entirely
+wanting in Madagascar. Let us first deal with this fact, of the absence of
+so many of the most dominant African groups. The explanation of this
+deficiency is by no means difficult, for the rich deposits of fossil
+mammals of Miocene or Pliocene age in France, Germany, Greece, and
+North-west India, have demonstrated the fact that all the great African
+mammals then inhabited Europe and temperate Asia. We also know that a
+little earlier (in Eocene times) tropical Africa was cut off from Europe
+and Asia by a sea stretching from the Atlantic to the Bay of Bengal, at
+which time Africa must have formed a detached island-continent such as
+Australia is now, and probably, like it, very poor in the higher forms of
+life. Coupling these two facts, the inference seems clear, that all the
+higher types of mammalia were developed in the great Euro-Asiatic continent
+(which then included Northern Africa), and that they only migrated into
+tropical Africa when the two continents became united by the upheaval of
+the sea-bottom, probably {419} in the latter portion of the Miocene or
+early in the Pliocene period.[99]
+
+It is clear, therefore, that if Madagascar had once formed part of Africa,
+but had been separated from it before Africa was united to Europe and Asia,
+it would not contain any of those kinds of animals which then first entered
+the country. But, besides the African mammals, we know that some birds now
+confined to Africa then inhabited Europe, and we may therefore fairly
+assume that all the more important groups of birds, reptiles, and insects,
+now abundant in Africa but absent from Madagascar, formed no part of the
+original African fauna, but entered the country only after it was joined to
+Europe and Asia.
+
+_Early History of Africa and Madagascar._--We have seen that Madagascar
+contains an abundance of mammals, and that most of them are of types either
+peculiar to, or existing also in, Africa; it follows that that continent
+must have had an earlier union with Europe, Asia, or America, or it could
+never have obtained any mammals at all.
+
+{420} Now these ancient African mammals are Lemurs, Insectivora, and small
+Carnivora, chiefly Viverridæ; and all these groups are known to have
+inhabited Europe in Eocene and Miocene times; and that the union was with
+Europe rather than with America is clearly proved by the fact that even the
+insectivorous Centetidæ, now confined to Madagascar and the West Indies,
+inhabited France in the Lower Miocene period, while the Viverridæ, or
+civets, which form so important a part of the fauna of Madagascar as well
+as of Africa, were abundant in Europe throughout the whole Tertiary period,
+but are not known to have ever lived in any part of the American continent.
+We here see the application of the principle which we have already fully
+proved and illustrated (Chapter IV., p. 60), that all extensive groups have
+a wide range at the period of their maximum development; but as they decay
+their area of distribution diminishes or breaks up into detached fragments,
+which one after another disappear till the group becomes extinct. Those
+animal forms which we now find isolated in Madagascar and other remote
+portions of the globe all belong to ancient groups which are in a decaying
+or nearly extinct condition, while those which are absent from it belong to
+more recent and more highly-developed types, which range over extensive and
+continuous areas, but have had no opportunity of reaching the more ancient
+continental islands.
+
+_Anomalies of Distribution and How to Explain Them._--If these
+considerations have any weight, it follows that there is no reason whatever
+for supposing any former direct connection between Madagascar and the
+Greater Antilles merely because the insectivorous Centetidæ now exist only
+in these two groups of islands; for we know that the ancestors of this
+family must once have had a much wider range, which almost certainly
+extended over the great northern continents. We might as reasonably suppose
+a land-connection across the Pacific to account for the camels of Asia
+having their nearest existing allies in the llamas and alpacas of the
+Peruvian Andes, and another between Sumatra and Brazil, in order that the
+ancestral tapir of one country might have passed over to the other. In both
+{421} these cases we have ample proof of the former wide extension of the
+group. Extinct camels of numerous species abounded in North America in
+Miocene, Pliocene, and even Post-pliocene times, and one has also been
+found in North-western India, but none whatever among all the rich deposits
+of mammalia in Europe. We are thus told, as clearly as possible, that from
+the North American continent as a centre the camel tribe spread westward,
+over now-submerged land at the shallow Behring Straits and Kamschatka Sea,
+into Asia, and southward along the Andes into South America. Tapirs are
+even more interesting and instructive. Their remotest known ancestors
+appear in Western Europe in the early portion of the Eocene period; in the
+latter Eocene and the Miocene other forms occur both in Europe and North
+America. These seem to have become extinct in North America, while in
+Europe they developed largely into many forms of true tapirs, which at a
+much later period found their way again to North, and thence to South,
+America, where their remains are found in caves and gravel deposits. It is
+an instructive fact that in the Eastern continent, where they were once so
+abundant, they have dwindled down to a single species, existing in small
+numbers in the Malay Peninsula, Sumatra, and Borneo only; while in the
+Western continent, where they are comparatively recent immigrants, they
+occupy a much larger area, and are represented by three or four distinct
+species. Who could possibly have imagined such migrations, and extinctions,
+and changes of distribution as are demonstrated in the case of the tapirs,
+if we had only the distribution of the existing species to found an opinion
+upon? Such cases as these--and there are many others equally striking--show
+us with the greatest distinctness how nature has worked in bringing about
+the examples of anomalous distribution that everywhere meet us; and we
+must, on every ground of philosophy and common sense, apply the same method
+of interpretation to the more numerous instances of anomalous distribution
+we discover among such groups as reptiles, birds, and insects, where we
+rarely have any direct evidence of their past migrations through the
+discovery of {422} fossil remains. Whenever we can trace the past history
+of any group of terrestrial animals, we invariably find that its actual
+distribution can be explained by migrations effected by means of
+comparatively slight modifications of our existing continents. In no single
+case have we any direct evidence that the distribution of land and sea has
+been radically changed during the whole lapse of the Tertiary and Secondary
+periods, while, as we have already shown in our fifth chapter, the
+testimony of geology itself, if fairly interpreted, upholds the same theory
+of the stability of our continents and the permanence of our oceans. Yet so
+easy and pleasant is it to speculate on former changes of land and sea with
+which to cut the gordian knot offered by anomalies of distribution, that we
+still continually meet with suggestions of former continents stretching in
+every direction across the deepest oceans, in order to explain the presence
+in remote parts of the globe of the same genera even of plants or of
+insects--organisms which possess such exceptional facilities both for
+terrestrial, aërial, and oceanic transport, and of whose distribution in
+early geological periods we generally know little or nothing.
+
+_The Birds of Madagascar, as Indicating a Supposed Lemurian
+Continent._--Having thus shown how the distribution of the land mammalia
+and reptiles of Madagascar may be well explained by the supposition of a
+union with Africa before the greater part of its existing fauna had reached
+it, we have now to consider whether, as some ornithologists think, the
+distribution and affinities of the birds present an insuperable objection
+to this view, and require the adoption of a hypothetical
+continent--Lemuria--extending from Madagascar to Ceylon and the Malay
+Islands.
+
+There are about one hundred and fifty land birds known from the island of
+Madagascar, of which a hundred and twenty-seven are peculiar; and about
+half of these peculiar species belong to peculiar genera, many of which are
+extremely isolated, so that it is often difficult to class them in any of
+the recognised families, or to determine their affinities to any living
+birds.[100] Among the other moiety, {423} belonging to known genera, we
+find fifteen which have undoubted African affinities, while five or six are
+as decidedly Oriental, the genera or nearest allied species being found in
+India or the Malay Islands. It is on the presence of these peculiar Indian
+types that Dr. Hartlaub, in his recent work on the _Birds of Madagascar and
+the Adjacent Islands_, lays great stress, as proving the former existence
+of "Lemuria"; while he considers the absence of such peculiar African
+families as the plantain-eaters, glossy-starlings, ox-peckers, barbets,
+honey-guides, hornbills, and bustards--besides a host of peculiar African
+genera--as sufficiently disproving the statement in my _Geographical
+Distribution of Animals_ that Madagascar is "more nearly related to the
+Ethiopian than to any other region," and that its fauna was evidently
+"mainly derived from Africa."
+
+But the absence of the numerous peculiar groups of African birds is so
+exactly parallel to the same phenomenon among mammals, that we are
+justified in imputing it to the same cause, the more especially as some of
+the very groups that are wanting--the plantain-eaters and the trogons, for
+example,--are actually known to have inhabited Europe along with the large
+mammalia which subsequently migrated to Africa. As to the peculiarly
+Eastern genera--such as Copsychus and Hypsipetes, with a Dicrurus, a
+Ploceus, a Cisticola, and a Scops, all closely allied to Indian or Malayan
+species--although very striking to the ornithologist, they certainly do not
+outweigh the fourteen African genera found in Madagascar. Their presence
+may, moreover, be accounted for more satisfactorily than by means of an
+ancient Lemurian continent, which, even if granted, would not explain the
+very facts adduced in its support.
+
+Let us first prove this latter statement.
+
+The supposed "Lemuria" must have existed, if at all, at so remote a period
+that the higher animals did not then inhabit either Africa or Southern
+Asia, and it must have {424} become partially or wholly submerged before
+they reached those countries; otherwise we should find in Madagascar many
+other animals besides Lemurs, Insectivora, and Viverridæ, especially such
+active arboreal creatures as monkeys and squirrels, such hardy grazers as
+deer or antelopes, or such wide-ranging carnivores as foxes or bears. This
+obliges us to date the disappearance of the hypothetical continent about
+the earlier part of the Miocene epoch at latest, for during the latter part
+of that period we know that such animals existed in abundance in every part
+of the great northern continents wherever we have found organic remains.
+But the Oriental birds in Madagascar, by whose presence Dr. Hartlaub
+upholds the theory of a Lemuria, are slightly modified forms of _existing
+Indian genera_, or sometimes, as Dr. Hartlaub himself points out, _species
+hardly distinguishable from those of India_. Now all the evidence at our
+command leads us to conclude that, even if these genera and species were in
+existence in the early Miocene period, they must have had a widely
+different distribution from what they have now. Along with so many African
+and Indian genera of mammals they then probably inhabited Europe, which at
+that epoch enjoyed a sub-tropical climate; and this is rendered almost
+certain by the discovery in the Miocene of France of fossil remains of
+trogons and jungle-fowl. If, then, these Indian birds date back to the very
+period during which alone Lemuria could have existed, that continent was
+quite unnecessary for their introduction into Madagascar, as they could
+have followed the same track as the mammalia of Miocene Europe and Asia;
+while if, as I maintain, they are of more recent date, then Lemuria had
+ceased to exist, and could not have been the means of their introduction.
+
+_Submerged Islands between Madagascar and India._--Looking at the
+accompanying map of the Indian Ocean, we see that between Madagascar and
+India there are now extensive shoals and coral reefs, such as are usually
+held to indicate subsidence; and we may therefore fairly postulate the
+former existence here of several large islands, some of them not much
+inferior to Madagascar itself. These reefs are all separated from each
+other by very deep {425} sea--much deeper than that which divides
+Madagascar from Africa, and we have therefore no reason to imagine their
+former union. But they would nevertheless greatly facilitate the
+introduction of Indian birds into the Mascarene Islands and Madagascar; and
+these facilities existing, such an immigration would be sure to take place,
+just as surely as American birds have entered the Galapagos and Juan
+Fernandez, as European birds now reach the Azores, and as Australian birds
+reach such a distant island as New Zealand. This would take place the more
+certainly because the Indian Ocean is a region of violent periodical storms
+at the changes of the monsoons, and we have seen in the case of the Azores
+and Bermuda how important a factor this is in determining the transport of
+birds across the ocean.
+
+[Illustration: MAP OF THE INDIAN OCEAN.
+
+Showing the position of banks less than 1,000 fathoms deep between Africa
+and the Indian Peninsula.]
+
+{426}
+
+The final disappearance of these now sunken islands does not, in all
+probability, date back to a very remote epoch; and this exactly accords
+with the fact that some of the birds, as well as the fruit-bats of the
+genus Pteropus, are very closely allied to Indian species, if not actually
+identical, others being distinct species of the same genera. The fact that
+not one closely-allied species or even genus of Indian or Malayan mammals
+is found in Madagascar, sufficiently proves that it is no land-connection
+that has brought about this small infusion of Indian birds and bats; while
+we have sufficiently shown, that, when we go back to remote geological
+times no land-connection in this direction was necessary to explain the
+phenomena of the distribution of the Lemurs and Insectivora. A
+land-connection with _some_ continent was undoubtedly necessary, or there
+would have been no mammalia at all in Madagascar; and the nature of its
+fauna on the whole, no less than the moderate depth of the intervening
+strait and the comparative approximation of the opposite shores, clearly
+indicate that the connection was with Africa.
+
+_Concluding Remarks on "Lemuria."_--I have gone into this question in some
+detail, because Dr. Hartlaub's criticism on my views has been reproduced in
+a scientific periodical,[101] and the supposed Lemurian continent is
+constantly referred to by quasi-scientific writers, as well as by
+naturalists and geologists, as if its existence had been demonstrated by
+facts, or as if it were absolutely necessary to postulate such a land in
+order to account for the entire series of phenomena connected with the
+Madagascar fauna, and especially with the distribution of the
+Lemuridæ.[102] I {427} think I have now shown, on the other hand, that it
+was essentially a provisional hypothesis, very useful in calling attention
+to a remarkable series of problems in geographical distribution, but not
+affording the true solution of those problems, any more than the hypothesis
+of an Atlantis solved the problems presented by the Atlantic Islands and
+the relations of the European and North American flora and fauna. The
+Atlantis is now rarely introduced seriously except by the absolutely
+unscientific, having received its death-blow by the chapter on Oceanic
+Islands in the _Origin of Species_, and the researches of Professor Asa
+Gray on the affinities of the North American and Asiatic floras. But
+"Lemuria" still keeps its place--a good example of the survival of a
+provisional hypothesis which offers what seems an easy solution of a
+difficult problem, and has received an appropriate and easily remembered
+name, long after it has been proved to be untenable.
+
+It is now more than fifteen years since I first showed, by a careful
+examination of all the facts to be accounted for, that the hypothesis of a
+Lemurian continent was alike unnecessary to explain one portion of the
+facts, and inadequate to explain the remaining portion.[103] Since that
+time I have seen no attempt even to discuss the question on general grounds
+in opposition to my views, nor on the other hand have those who have
+hitherto supported the hypothesis taken any opportunity of acknowledging
+its weakness and inutility. I have therefore here explained my reasons for
+rejecting it somewhat more fully and in a more popular form, in the hope
+that a check may thus be placed on the continued re-statement of this
+unsound theory as if it were one of the accepted conclusions of modern
+science.
+
+{428}
+
+_The Mascarene Islands._[104]--In the _Geographical Distribution of
+Animals_, a summary is given of all that was known of the zoology of the
+various islands near Madagascar, which to some extent partake of its
+peculiarities, and with it form the Malagasy sub-region of the Ethiopian
+region. As no great additions have since been made to our knowledge of the
+fauna of these islands, and my object in this volume being more especially
+to illustrate the mode of solving distributional problems by means of the
+most suitable examples, I shall now confine myself to pointing out how far
+the facts presented by these outlying islands support the views already
+enunciated with regard to the origin of the Madagascar fauna.
+
+_The Comoro Islands._--This group of islands is situated nearly midway
+between the northern extremity of Madagascar and the coast of Africa. The
+four chief islands vary between sixteen and forty miles in length, the
+largest being 180 miles from the coast of Africa, while one or two smaller
+islets are less than 100 miles from Madagascar. All are volcanic, Great
+Comoro being an active volcano 8,500 feet high; and, as already stated,
+they are situated on a submarine bank with less than 500 fathoms soundings,
+connecting Madagascar with Africa. There is reason to believe, however,
+that these islands are of comparatively recent origin, and that the bank
+has been formed by matter ejected by the volcanoes or by upheaval. Anyhow,
+there is no indication whatever of there having been here a land-connection
+between Madagascar and Africa; while the islands themselves have been
+mainly colonised from Madagascar, some of them making a near approach to
+the 100-fathom bank which surrounds that island.
+
+The Comoros contain two land mammals, a lemur and a civet, both of
+Madagascar genera and the latter an identical species, and there is also a
+peculiar species of fruit-bat (_Pteropus comorensis_), a group which ranges
+from Australia to Asia and Madagascar but is unknown in Africa. Of
+land-birds forty-one species are known, of {429} which sixteen are peculiar
+to the islands, twenty-one are found also in Madagascar, and three found in
+Africa and not in Madagascar; while of the peculiar species, six belong to
+Madagascar or Mascarene genera. A species of Chameleon is also peculiar to
+the islands.
+
+These facts point to the conclusion that the Comoro Islands have been
+formerly more nearly connected with Madagascar than they are now, probably
+by means of intervening islets and the former extension of the latter
+island to the westward, as indicated by the extensive shallow bank at its
+northern extremity, so as to allow of the easy passage of birds, and the
+occasional transmission of small mammalia by means of floating trees.[105]
+
+_The Seychelles Archipelago._--This interesting group consists of about
+thirty small islands situated 700 miles N.N.E. of Madagascar, or almost
+exactly in the line formed by continuing the central ridge of that great
+island. The Seychelles stand upon a rather extensive shallow bank, the
+100-fathom line around them enclosing an area nearly 200 miles long by 100
+miles wide, while the 500-fathom line shows an extension of nearly 100
+miles in a southern direction. All the larger islands are of granite, with
+mountains rising to 3,000 feet in Mahé, and to from 1,000 to 2,000 feet in
+several of the other islands. We can therefore hardly doubt that they form
+a portion of the great line of upheaval which produced the central granitic
+mass of Madagascar, intervening points being indicated by the Amirantes,
+the Providence, and the Farquhar Islands, which, though all coralline,
+probably rest on a granitic basis. Deep channels of more than 1,000 fathoms
+now separate these islands from each other, and if they were ever
+sufficiently elevated to be united, it was probably at a very remote epoch.
+
+The Seychelles may thus have had ample facilities for receiving from
+Madagascar such immigrants as can pass over narrow seas; and, on the other
+hand, they were equally favourably situated as regards the extensive Saya
+de Malha and Cargados banks, which were probably once {430} large islands,
+and may have supported a rich insular flora and fauna of mixed Mascarene
+and Indian type. The existing fauna and flora of the Seychelles must
+therefore be looked upon as the remnants which have survived the partial
+submergence of a very extensive island; and the entire absence of
+non-aërial mammalia may be due, either to this island having never been
+actually united to Madagascar, or to its having since undergone so much
+submergence as to have led to the extinction of such mammals as may once
+have inhabited it. The birds and reptiles, however, though few in number,
+are very interesting, and throw some further light on the past history of
+the Seychelles.
+
+_Birds of the Seychelles._--Fifteen indigenous land-birds are known to
+inhabit the group, thirteen of which are peculiar species,[106] belonging
+to genera which occur also in Madagascar or Africa. The genera which are
+more peculiarly Indian are,--Copsychus and Hypsipetes, also found in
+Madagascar; and Palæornis, which has species in Mauritius and Rodriguez, as
+well as one on the continent of Africa. A black parrot (Coracopsis),
+congeneric with two species that inhabit Madagascar and with one that is
+peculiar to the Comoros; and a beautiful red-headed blue pigeon
+(_Alectorænas pulcherrimus_) allied to those of Madagascar and Mauritius,
+but very distinct, are the most remarkable species characteristic of this
+group of islands.
+
+_Reptiles and Amphibia of the Seychelles._--The reptiles and amphibia are
+rather numerous and very interesting, indicating clearly that the islands
+can hardly be classed as oceanic. There are seven species of lizards, three
+being peculiar to the islands, while the others have rather a wide range.
+The first is a chameleon--defenceless {431} slow-moving lizards, especially
+abundant in Madagascar, from which no less than eighteen species are now
+known, about the same number as on the continent of Africa. The Seychelles
+species (_Chamæleon tigris_) also occurs at Zanzibar. The next are skinks
+(Scincidæ), small ground-lizards with a wide distribution in the Eastern
+hemisphere. Two species are however peculiar to the islands--_Mabuia
+seychellensis_ and _M. wrightii_. The other peculiar species is one of the
+geckoes (Geckotidæ) named _Æluronyx seychellensis_, and there are also
+three other geckoes, _Phelsuma madagascarensis_, _Gehyra mutilata_ and
+_Hemidactylus frenatus_, the two latter having a wide distribution in the
+tropical regions of both hemispheres. These lizards, clinging as they do to
+trees and timber, are exceedingly liable to be carried in ships from one
+country to another, and I am told by Dr. Günther that some are found almost
+every year in the London Docks. It is therefore probable, that when species
+of this family have a very wide range they have been assisted in their
+migrations by man, though their habit of clinging to trees also renders
+them likely to be floated with large pieces of timber to considerable
+distances. Dr. Percival Wright, to whom I am indebted for much information
+on the productions of the Seychelles Archipelago, informs me that the
+last-named species varies greatly in colour in the different islands, so
+that he could always tell from which particular island a specimen had been
+brought. This is analogous to the curious fact of certain lizards on the
+small islands in the Mediterranean being always very different in colour
+from those of the mainland, usually becoming rich blue or black (see
+_Nature_, Vol. XIX. p. 97); and we thus learn how readily in some cases
+differences of colour are brought about, either directly or indirectly, by
+local conditions.
+
+Snakes, as is usually the case in small or remote islands, are far less
+numerous than lizards, only two species being known. One, _Dromicus
+seychellensis_, is a peculiar species of the family Colubridæ, the rest of
+the genus being found in Madagascar and South America. The other, _Boodon
+geometricus_, one of the Lycodontidæ, or fanged ground-snakes, is also
+peculiar. So far, then, as the reptiles are {432} concerned, there is
+nothing but what is easily explicable by what we know of the general means
+of distribution of these animals.
+
+We now come to the Amphibia, which are represented in the Seychelles by two
+tailless and two serpent-like forms. The frogs are _Rana mascareniensis_,
+found also in Mauritius, Bourbon, Angola, and Abyssinia, and probably all
+over tropical Africa; and _Megalixalus seychellensis_ a peculiar tree-frog
+having allies in Madagascar and tropical Africa. It is found, Dr. Wright
+informs me, on the Pandani or screw-pines; and as these form a very
+characteristic portion of the vegetation of the Mascarene Islands, all the
+species being peculiar and confined each to a single island or small group,
+we may perhaps consider it as a relic of the indigenous fauna of that more
+extensive land of which the present islands are the remains.
+
+The serpentine Amphibia are represented by two species of Cæcilia. These
+creatures externally resemble large worms, except that they have a true
+head with jaws and rudimentary eyes, while internally they have of course a
+true vertebrate skeleton. They live underground, burrowing by means of the
+ring-like folds of the skin which simulate the jointed segments of a worm's
+body, and when caught they exude a viscid slime. The young have external
+gills which are afterwards replaced by true lungs, and this peculiar
+metamorphosis shows that they belong to the amphibia rather than to the
+reptiles. The Cæcilias are widely but very sparingly distributed through
+all the tropical regions; a fact which may, as we have seen, be taken as an
+indication of the great antiquity of the group, and that it is now verging
+towards extinction. In the Seychelles Islands there appear to be three
+species of these singular animals. _Cryptopsophis multiplicatus_ is
+confined to the islands; _Herpele squalostoma_ is found also in Western
+India and in Africa; while _Hypogeophis rostratus_ inhabits both West
+Africa and South America.[107] This last is certainly one of the most
+remarkable cases of the wide and discontinuous distribution of a species;
+and {433} when we consider the habits of life of these animals and the
+extreme slowness with which it is likely they can migrate into new areas,
+we can hardly arrive at any other conclusion than that this species once
+had an almost world-wide range, and that in the process of dying out it has
+been left stranded, as it were, in these three remote portions of the
+globe. The extreme stability and long persistence of specific form which
+this implies is extraordinary, but not unprecedented, among the lower
+vertebrates. The crocodiles of the Eocene period differ but slightly from
+those of the present day, while a small freshwater turtle from the Pliocene
+deposits of the Siwalik Hills is absolutely identical with a still living
+Indian species, _Emys tectus_. The mud-fish of Australia, _Ceratodus
+forsteri_ is a very ancient type, and may well have remained specifically
+unchanged since early Tertiary times. It is not, therefore, incredible that
+this Seychelles Cæcilia may be the oldest land vertebrate now living on the
+globe; dating back to the early part of the Tertiary period, when the warm
+climate of the northern hemisphere in high latitudes and the union of the
+Asiatic and American continents allowed of the migration of such types over
+the whole northern hemisphere, from which they subsequently passed into the
+southern hemisphere, maintaining themselves only in certain limited areas,
+where the physical conditions were especially favourable, or where they
+were saved from the attacks of enemies or the competition of higher forms.
+
+_Fresh-water Fishes._--The only other vertebrates in the Seychelles are two
+fresh-water fishes abounding in the streams and rivulets. One, _Haplochilus
+playfairii_ is peculiar to the islands, but there are allied species in
+Madagascar. It is a pretty little fish about four inches long, of an olive
+colour, with rows of red spots, and is very abundant in some of the
+mountain streams. The fishes of this genus, as I am informed by Dr.
+Günther, often inhabit both sea and fresh water, so that their migration
+from {434} Madagascar to the Seychelles and subsequent modification, offers
+no difficulty. The other species is _Fundulus orthonotus_, found also on
+the east coast of Africa; and as both belong to the same
+family--Cyprinodontidæ--this may possibly have migrated in a similar
+manner.
+
+_Land-shells._--The only other group of animals inhabiting the Seychelles
+which we know with any approach to completeness, are the land and
+fresh-water mollusca, but they do not furnish any facts of special
+interest. About forty species are known, and Mr. Geoffrey Nevill, who has
+studied them, thinks their meagre number is chiefly owing to the
+destruction of so much of the forests which once covered the islands. Seven
+of the species--and among them one of the most conspicuous, _Achatina
+fulica_--have almost certainly been introduced; and the remainder show a
+mixture of Madagascar and Indian forms, with a preponderance of the latter.
+Five genera--Streptaxis, Cyathoponea, Onchidium, Helicina and Paludomus,
+are mentioned as being especially Indian, while only two--Tropidophora and
+Gibbus, are found in Madagascar but not in India.[108] About two-thirds of
+the species appear to be peculiar to the islands.
+
+_Mauritius, Bourbon and Rodriguez._--These three islands are somewhat out
+of place in this chapter, because they really belong to the oceanic group,
+being of volcanic formation, surrounded by deep sea, and possessing no
+indigenous mammals or amphibia. Yet their productions are so closely
+related to those of Madagascar, to which they may be considered as
+attendant satellites, that it is absolutely necessary to associate them
+together if we wish to comprehend and explain their many interesting
+features.
+
+Mauritius and Bourbon are lofty volcanic islands, evidently of great
+antiquity. They are about 100 miles apart, and the sea between them is less
+than 1,000 fathoms deep, while on each side it sinks rapidly to depths of
+2,400 and 2,600 fathoms. We have therefore no reason to believe that they
+have ever been connected with {435} Madagascar, and this view is strongly
+supported by the character of their indigenous fauna. Of this, however, we
+have not a very complete or accurate knowledge, for though both islands
+have long been occupied by Europeans, the study of their natural products
+was for a long time greatly neglected, and owing to the rapid spread of
+sugar cultivation, the virgin forests, and with them no doubt many native
+animals, have been almost wholly destroyed. There is, however, no good
+evidence of there ever having been any indigenous mammals or amphibia,
+though both are now found and are often recorded among the native
+animals.[109]
+
+The smaller and more remote island, Rodriguez, is also volcanic; but it
+has, besides a good deal of coralline rock, an indication of partial
+submergence helping to account for the poverty of its fauna and flora. It
+stands on a 100-fathom bank of considerable extent, but beyond this the
+{436} sea rapidly deepens to more than 2,000 fathoms, so that it is truly
+oceanic like its larger sister isles.
+
+_Birds._--The living birds of these islands are few in number and consist
+mainly of peculiar species of Mascarene types, together with two peculiar
+genera--Oxynotus belonging to the Campephagidæ or caterpillar-catchers, a
+family abundant in the old-world tropics; and a dove, Trocazza, forming a
+peculiar sub-genus. The origin of these birds offers no difficulty, looking
+at the position of the islands and of the surrounding shoals and islets.
+
+_Extinct Birds._--These three islands are, however, preeminently remarkable
+as having been the home of a group of large ground-birds, quite incapable
+of flight, and altogether unlike anything found elsewhere on the globe; and
+which, though once very abundant, have become totally extinct within the
+last two hundred years. The best known of these birds is the dodo, which
+inhabited Mauritius; while allied species certainly lived in Bourbon and
+Rodriguez, abundant remains of the species of the latter island--the
+"solitaire," having been discovered, corresponding with the figure and
+description given of it by Legouat, who resided in Rodriguez in 1692. These
+birds constitute a distinct family, Dididæ, allied to the pigeons but very
+isolated. They were quite defenceless, and were rapidly exterminated when
+man introduced dogs, pigs, and cats into the island, and himself sought
+them for food. The fact that such perfectly unprotected creatures survived
+in great abundance to a quite recent period in these three islands only,
+while there is no evidence of their ever having inhabited any other
+countries whatever, is itself almost demonstrative that Mauritius, Bourbon,
+and Rodriguez are very ancient but truly oceanic islands. From what we know
+of the general similarity of Miocene birds to living genera and families,
+it seems clear that the origin of so remarkable a type as the dodos must
+date back to early Tertiary times. If we suppose some ancestral
+ground-feeding pigeon of large size to have reached the group by means of
+intervening islands afterwards submerged, and to have thenceforth remained
+to increase and multiply unchecked by the attacks of any more {437}
+powerful animals, we can well understand that the wings, being useless,
+would in time become almost aborted.[110] It is also not improbable that
+this process would be aided by natural selection, because the use of wings
+might be absolutely prejudicial to the birds in their new home. Those that
+flew up into trees to roost, or tried to cross over the mouths of rivers,
+might be blown out to sea and destroyed, especially during the hurricanes
+which have probably always more or less devastated the islands; while on
+the other hand the more bulky and short-winged individuals, who took to
+sleeping on the ground in the forest, would be preserved from such dangers,
+and perhaps also from the attacks of birds of prey which may always have
+visited the islands. But whether or no this was the mode by which these
+singular birds acquired their actual form and structure, it is perfectly
+certain that their existence and development depended on complete isolation
+and on freedom from the attacks of enemies. We have no single example of
+such defenceless birds having ever existed on a continent at any geological
+period, whereas analogous though totally distinct forms do exist in New
+Zealand, where enemies are equally wanting. On the other hand, every
+continent has always produced abundance of carnivora adapted to prey upon
+the herbivorous animals inhabiting it at the same period; and we may
+therefore be sure that {438} these islands have never formed part of a
+continent during any portion of the time when the dodos inhabited them.
+
+It is a remarkable thing that an ornithologist of Dr. Hartlaub's
+reputation, looking at the subject from a purely ornithological point of
+view, should yet entirely ignore the evidence of these wonderful and unique
+birds against his own theory, when he so confidently characterises Lemuria
+as "that sunken land, which, containing parts of Africa, must have extended
+far eastward over Southern India and Ceylon, and the highest points of
+which we recognise in the volcanic peaks of Bourbon and Mauritius, and in
+the central range of Madagascar itself--the last resorts of the mostly
+extinct Lemurine race which formerly peopled it."[111] It is here implied
+that lemurs formerly inhabited Bourbon and Mauritius, but of this there is
+not a particle of evidence, and we feel pretty sure that had they done so
+the dodos would never have been developed there. In Madagascar there are no
+traces of dodos, while there are remains of extinct gigantic struthious
+birds of the genus Æpyornis, which were no doubt as well able to protect
+themselves against the smaller carnivora as are the ostriches, emus, and
+cassowaries in their respective countries at the present day.
+
+The whole of the evidence at our command, therefore, tends to establish in
+a very complete manner the "oceanic" character of the three
+islands--Mauritius, Bourbon, and Rodriguez, and that they have never formed
+part of "Lemuria" or of any continent.
+
+_Reptiles._--Mauritius, like Bourbon, has lizards, some of which are
+peculiar species; but no snakes, and no frogs or toads but such as have
+been introduced.[112] Strange to say, however, a small islet called Round
+Island, only about a mile across, and situated about fourteen miles
+north-east of Mauritius, possesses a snake which is not only unknown in
+Mauritius, but also in any other part of the world, being {439} altogether
+confined to this minute islet! It belongs to the boa family, and forms a
+peculiar and very distinct genus, Casaria, whose nearest allies seem to be
+the Ungalia of Cuba and Bolyeria of Australia. It is hardly possible to
+believe that this serpent has very long maintained itself on so small an
+island; and though we have no record of its existence on Mauritius, it may
+very well have inhabited the lowland forests without being met with by the
+early settlers; and the introduction of swine, which soon ran wild and
+effected the final destruction of the dodo, may also have been fatal to
+this snake. It is, however, now almost certainly confined to the one small
+islet, and is probably the land-vertebrate of most restricted distribution
+on the globe.
+
+On the same island there is a small lizard, _Scelotes bojeri_, recorded
+also from Mauritius and Bourbon, though it appears to be rare in both
+islands; but a gecko, _Phelsuma guentheri_, is restricted to the island. As
+Round Island is connected with Mauritius by a bank under a hundred fathoms
+below the surface, it has probably been once joined to it, and when first
+separated would have been both much larger and much nearer the main island,
+circumstances which would greatly facilitate the transmission of these
+reptiles to their present dwelling-place, where they have been able to
+maintain themselves owing to the complete absence of competition, while
+some of them have become extinct in the larger island.
+
+_Flora of Madagascar and the Mascarene Islands._--The botany of the great
+island of Madagascar has been perhaps more thoroughly explored than that of
+the opposite coasts of Africa, so that its peculiarities may not be really
+so great as they now appear to be. Yet there can be no doubt of its extreme
+richness and grandeur, its remarkable speciality, and its anomalous
+external relations. It is characterised by a great abundance of
+forest-trees and shrubs of peculiar genera or species, and often adorned
+with magnificent flowers. Some of these are allied to African forms, others
+to those of Asia, and it is said that of the two affinities the latter
+preponderates. But there are also, as in the animal world, some decided
+South {440} American relations, while other groups point to Australia, or
+are altogether isolated.
+
+No less than 3,740 flowering plants are now known from Madagascar with 360
+ferns and fern-allies. The most abundant natural orders are the following:
+
+ Species.
+ Leguminosæ 346
+ Ferns 318
+ Compositæ 281
+ Euphorbiaceæ 228
+ Orchideæ 170
+ Cyperaceæ 160
+ Rubiaceæ 147
+ Acanthaceæ 131
+ Gramineæ 130
+
+The flora contains representatives of 144 natural orders and 970 genera,
+one of the former and 148 of the latter being peculiar to the island. The
+peculiar order, Chælnaceæ, comprises seven genera and twenty-four species;
+while Rubiaceæ and Compositæ have the largest number of peculiar genera,
+followed by Leguminosæ and Melastomaceæ. Nearly three-fourths of the
+species are endemic.
+
+Beautiful flowers are not conspicuous in the flora of Madagascar, though it
+contains several magnificent flowering plants. A shrub with the dreadful
+name _Harpagophytum Grandidieri_ has bunches of gorgeous red flowers;
+_Tristellateia madagascariensis_ is a climbing plant with spikes of rich
+yellow flowers; while _Poinciana regia_, a tall tree, _Rhodolæna altivola_
+and _Astrapoea Wallichii_, shrubs, are among the most magnificent flowering
+plants in the world. _Disa Buchenaviana_, _Commelina madagascarica_, and
+_Tachiadenus platypterus_ are fine blue-flowered plants, while the superb
+orchid _Angræcum sesquipedale_, _Vinca rosea_, _Euphorbia splendens_, and
+_Stephanotis floribunda_, have been long cultivated in our hot-houses.
+There are also many handsome Combretaceæ, Rubiaceæ, and Leguminosæ; but, as
+in most tropical regions, this wealth of floral beauty has to be searched
+for, and produces little effect in the landscape.
+
+The affinities of the Madagascar flora are to a great extent in accordance
+with those of the fauna. The tropical portion of the flora agrees closely
+with that of tropical Africa, while the plants of the highlands are {441}
+equally allied to those of the Cape and of the mountains of Central Africa.
+Some Asiatic types are present which do not occur in Africa; and even the
+curious American affinities of some of the animals are reproduced in the
+vegetable kingdom. These last are so interesting that they deserve to be
+enumerated. An American genus of Euphorbiaceæ, Omphalea, has one species in
+Madagascar, and Pedilanthus, another genus of the same natural order, has a
+similar distribution. Myrosma, an American genus of Scitamineæ has one
+Madagascar species; while the celebrated "travellers' tree," _Ravenala
+madagascariensis_, belonging to the order Musaceæ, has its nearest ally in
+a plant inhabiting N. Brazil and Guiana. Echinolæna, a genus of grasses,
+has the same distribution.[113]
+
+Of the flora of the smaller Madagascarian islands we possess a fuller
+account, owing to the recent publication of Mr. Baker's _Flora of the
+Mauritius and the Seychelles_, including also Rodriguez. The total number
+of species in this flora is 1,058, more than half of which (536) are
+exclusively Mascarene--that is, found only in some of the islands of the
+Madagascar group, while nearly a third (304) are endemic or confined to
+single islands. Of the widespread plants sixty-six are found in Africa but
+not in Asia, and eighty-six in Asia but not in Africa, showing a similar
+Asiatic preponderance to what is said to occur in Madagascar. With the
+genera, however, the proportions are different, for I find by going through
+the whole of the generic distributions as given by Mr. Baker, that out of
+the 440 genera of wild plants fifty are endemic, twenty-two are Asiatic but
+not African, while twenty-eight are African but not Asiatic. This implies
+that the more ancient connection has been on the side of Africa, while a
+more recent immigration, shown by identity of species, has come from the
+side of Asia; and it is already certain that when the flora of Madagascar
+is more thoroughly worked out, a still greater African preponderance will
+be found in that island.
+
+{442}
+
+A few Mascarene genera are found elsewhere only in South America,
+Australia, or Polynesia; and there are also a considerable number of genera
+whose metropolis is South America, but which are represented by one or more
+species in Madagascar, and by a single often widely distributed species in
+Africa. This fact throws light upon the problem offered by those mammals,
+reptiles, and insects of Madagascar which now have their only allies in
+South America, since the two cases would be exactly parallel were the
+African plants to become extinct. Plants, however, are undoubtedly more
+long-lived specifically than animals--especially the more highly organised
+groups, and are less liable to complete extinction through the attacks of
+enemies or through changes of climate or of physical geography; hence we
+find comparatively few cases in which groups of Madagascar plants have
+their _only_ allies in such distant regions as America and Australia, while
+such cases are numerous among animals, owing to the extinction of the
+allied forms in intervening areas, for which extinction, as we have already
+shown, ample cause can be assigned.
+
+_Curious Relations of Mascarene Plants._--Among the curious affinities of
+Mascarene plants we have culled the following from Mr. Baker's volume.
+Trochetia, a genus of Sterculiaceæ, has four species in Mauritius, one in
+Madagascar, and one in the remote island of St. Helena. Mathurina, a genus
+of Turneraceæ, consisting of a single species peculiar to Rodriguez, has
+its nearest ally in another monotypic genus, Erblichia, confined to Central
+America. Siegesbeckia, one of the Compositæ, consists of two species, one
+inhabiting the Mascarene islands, the other Peru. Labourdonasia, a genus of
+Sapotaceæ, has two species in Mauritius, one in Natal, and one in Cuba.
+Nesogenes, belonging to the verbena family, has one species in Rodriguez
+and one in Polynesia. Mespilodaphne, an extensive genus of Lauraceæ, has
+six species in the Mascarene islands, and all the rest (about fifty
+species) in South America. Nepenthes, the well-known pitcher plants, are
+found chiefly in the Malay Islands, South China, and Ceylon, with species
+in the Seychelles Islands, {443} and in Madagascar. Milla, a large genus of
+Liliaceæ, is exclusively American, except one species found in Mauritius
+and Bourbon. Agauria, a genus of Ericaceæ, is found in Madagascar, the
+Mascarene islands, the plateau of Central Africa, and the Camaroon
+Mountains in West Africa. An acacia, found in Mauritius and Bourbon (_A.
+heterophylla_), can hardly be separated specifically from _Acacia koa_ of
+the Sandwich Islands. The genus Pandanus, or screw-pine, has sixteen
+species in the three islands--Mauritius, Rodriguez, and the Seychelles--all
+being peculiar, and none ranging beyond a single island. Of palms there are
+fifteen species belonging to ten genera, and all these genera are peculiar
+to the islands. We have here ample evidence that plants exhibit the same
+anomalies of distribution in these islands as do the animals, though in a
+smaller proportion; while they also exhibit some of the transitional stages
+by which these anomalies have, in all probability, been brought about,
+rendering quite unnecessary any other changes in the distribution of sea
+and land than physical and geological evidence warrants.[114]
+
+{444}
+
+_Fragmentary Character of the Mascarene Flora._--Although the peculiar
+character and affinities of the vegetation of these islands is sufficiently
+apparent, there can be little doubt that we only possess a fragment of the
+rich flora which once adorned them. The cultivation of sugar, and other
+tropical products, has led to the clearing away of the virgin forests from
+all the lowlands, plateaus, and accessible slopes of the mountains, so that
+remains of the aboriginal woodlands only linger in the recesses of the
+hills, and numbers of forest-haunting plants must inevitably have been
+exterminated. The result is, that nearly three hundred species of foreign
+plants have run wild in Mauritius, and have in their turn helped to
+extinguish the native {445} species. In the Seychelles, too, the indigenous
+flora has been almost entirely destroyed in most of the islands, although
+the peculiar palms, from their longevity and comparative hardiness, have
+survived. Mr. Geoffrey Nevill tells us, that at Mahé, and most of the other
+islands visited by him, it was only in a few spots near the summits of the
+hills that he could perceive any remains of the ancient flora. Pine-apples,
+cinnamon, bamboos, and other plants have obtained a firm footing, covering
+large tracts of country and killing the more delicate native flowers and
+ferns. The pine-apple, especially, grows almost to the tops of the
+mountains. Where the timber and shrubs have been destroyed, the water
+falling on the surface immediately cuts channels, runs off rapidly, and
+causes the land to become dry and arid; and the same effect is largely seen
+both in Mauritius and Bourbon, where, originally, dense forest covered the
+entire surface, and perennial moisture, with its ever-accompanying
+luxuriance of vegetation, prevailed.
+
+_Flora of Madagascar Allied to that of South Africa._--In my _Geographical
+Distribution of Animals_ I have remarked on the relation between the
+insects of Madagascar and those of south temperate Africa, and have
+speculated on a great _southern_ extension of the continent at the time
+when Madagascar was united with it. As supporting this view I now quote Mr.
+Bentham's remarks on the Compositæ. He says: "The connections of the
+Mascarene endemic Compositæ, especially those of Madagascar itself, are
+eminently with the southern and sub-tropical African races; the more
+tropical races, Plucheineæ, &c., may be rather more of an Asiatic type." He
+further says that the Composite flora is almost as strictly endemic as that
+of the Sandwich Islands, and that it is much diversified, with evidences of
+great antiquity, while it shows insular characteristics in the tendency to
+tall shrubby or arborescent forms in several of the endemic or prevailing
+genera.
+
+_Preponderance of Ferns in the Mascarene Flora._--A striking character of
+the flora of these smaller Mascarene islands is the great preponderance of
+ferns, and next to them of orchideæ. The following figures are taken from
+{446} Mr. Baker's _Flora_ for Mauritius and the Seychelles, and from an
+estimate by M. Frappier of the flora of Bourbon given in Maillard's volume
+already quoted:--
+
+ _Mauritius, &c._ _Bourbon._
+
+ Ferns 168 Ferns 240
+ Orchideæ 79 Orchideæ 120
+ Gramineæ 69 Gramineæ 60
+ Cyperaceæ 62 Compositæ 60
+ Rubiaceæ 57 Leguminosæ 36
+ Euphorbiaceæ 45 Rubiaceæ 24
+ Compositæ 43 Cyperaceæ 24
+ Leguminosæ 41 Euphorbiaceæ 18
+
+The cause of the great preponderance of ferns in oceanic islands has
+already been discussed in my book on _Tropical Nature_; and we have seen
+that Mauritius, Bourbon, and Rodriguez must be classed as such, though from
+their proximity to Madagascar they have to be considered as satellites to
+that great island. The abundance of orchids, the reverse of what occurs in
+remoter oceanic islands, may be in part due to analogous causes. Their
+usually minute and abundant seeds would be as easily carried by the wind as
+the spores of ferns, and their frequent epiphytic habit affords them an
+endless variety of stations on which to vegetate, and at the same time
+removes them in a great measure from the competition of other plants. When,
+therefore, the climate is sufficiently moist and equable, and there is a
+luxuriant forest vegetation, we may expect to find orchids plentiful on
+such tropical islands as possess an abundance of insects adapted to
+fertilise them, and which are not too far removed from other lands or
+continents from which their seeds might be conveyed.
+
+_Concluding Remarks on Madagascar and the Mascarene Islands._--There is
+probably no portion of the globe that contains within itself so many and
+such varied features of interest connected with geographical distribution,
+or which so well illustrates the mode of solving the problems it presents,
+as the comparatively small insular region which comprises the great island
+of Madagascar and the smaller islands and island-groups which immediately
+surround it. In Madagascar we have a continental island of the first rank,
+and undoubtedly of immense antiquity; we have detached fragments of this
+island in the Comoros and {447} Aldabra; in the Seychelles we have the
+fragments of another very ancient island, which may perhaps never have been
+continental; in Mauritius, Bourbon, and Rodriguez we have three undoubtedly
+oceanic islands; while in the extensive banks and coral reefs of Cargados,
+Saya de Malha, the Chagos, and the Maldive Isles, we have indications of
+the submergence of many large islands which may have aided in the
+transmission of organisms from the Indian Peninsula. But between and around
+all these islands we have depths of 2,500 fathoms and upwards, which
+renders it very improbable that there has ever been here a continuous land
+surface, at all events during the Tertiary or Secondary periods of geology.
+
+It is most interesting and satisfactory to find that this conclusion,
+arrived at solely by a study of the form of the sea-bottom and the general
+principle of oceanic permanence, is fully supported by the evidence of the
+organic productions of the several islands; because it gives us confidence
+in those principles, and helps to supply us with a practical demonstration
+of them. We find that the entire group contains just that amount of Indian
+forms which could well have passed from island to island; that many of
+these forms are slightly modified species, indicating that the migration
+occurred during late Tertiary times, while others are distinct genera,
+indicating a more ancient connection; but in no one case do we find animals
+which necessitate an actual land-connection, while the numerous Indian
+types of mammalia, reptiles, birds, and insects, which must certainly have
+passed over had there been such an actual land-connection, are totally
+wanting. The one fact which has been supposed to require such a
+connection--the distribution of the lemurs--can be far more naturally
+explained by a general dispersion of the group from Europe, where we know
+it existed in Eocene times; and such an explanation applies equally to the
+affinity of the Insectivora of Madagascar and Cuba; the snakes
+(Herpetodryas, &c.) of Madagascar and America; and the lizards
+(Cryptoblepharus) of Mauritius and Australia. To suppose, in all these
+cases, and in many others, a direct land-connection, is really absurd,
+because {448} we have the evidence afforded by geology of wide differences
+of distribution directly we pass beyond the most recent deposits; and when
+we go back to Mesozoic--and still more to Palæozoic--times, the majority of
+the groups of animals and plants appear to have had a world-wide range. A
+large number of our European Miocene genera of vertebrates were also Indian
+or African, or even American; the South American Tertiary fauna contained
+many European types; while many Mesozoic reptiles and mollusca ranged from
+Europe and North America to Australia and New Zealand.
+
+By very good evidence (the occurrence of wide areas of marine deposits of
+Eocene age), geologists have established the fact that Africa was cut off
+from Europe and Asia by an arm of the sea in early Tertiary times, forming
+a large island-continent. By the evidence of abundant organic remains we
+know that all the types of large mammalia now found in Africa (but which
+are absent from Madagascar) inhabited Europe and Asia, and many of them
+also North America, in the Miocene period. At a still earlier epoch Africa
+may have received its lower types of mammals--lemurs, insectivora, and
+small carnivora, together with its ancestral struthious birds, and its
+reptiles and insects of American or Australian affinity; and at this period
+it was joined to Madagascar. Before the later continental period of Africa,
+Madagascar had become an island; and thus, when the large mammalia from the
+northern continent overran Africa, they were prevented from reaching
+Madagascar, which thenceforth was enabled to develop its singular forms of
+low-type mammalia, its gigantic ostrich-like Æpyornis, its isolated birds,
+its remarkable insects, and its rich and peculiar flora. From it the
+adjacent islands received such organisms as could cross the sea; while they
+transmitted to Madagascar some of the Indian birds and insects which had
+reached them.
+
+The method we have followed in these investigations is to accept the
+results of geological and palæontological science, and the ascertained
+facts as to the powers of dispersal of the various animal groups; to take
+full account of the laws of evolution as affecting distribution, {449} and
+of the various ocean depths as implying recent or remote union of islands
+with their adjacent continents; and the result is, that wherever we possess
+a sufficient knowledge of these various classes of evidence, we find it
+possible to give a connected and intelligible explanation of all the most
+striking peculiarities of the organic world. In Madagascar we have
+undoubtedly one of the most difficult of these problems; but we have, I
+think, fairly met and conquered most of its difficulties. The complexity of
+the organic relations of this island is due, partly to its having derived
+its animal forms from two distinct sources--from one continent through a
+direct land-connection, and from another by means of intervening islands
+now submerged; but, mainly to the fact of its having been separated from a
+continent which is now, zoologically, in a very different condition from
+that which prevailed at the time of the separation; and to its having been
+thus able to preserve a number of types which may date back to the Eocene,
+or even to the Cretaceous, period. Some of these types have become
+altogether extinct elsewhere; others have spread far and wide over the
+globe, and have survived only in a few remote countries--and especially in
+those which have been more or less secured by their isolated position from
+the incursions of the more highly-developed forms of later times. This
+explains why it is that the nearest allies of the Madagascar fauna and
+flora are now so often to be found in South America or Australia--countries
+in which low forms of mammalia and birds still largely prevail;--it being
+on account of the long-continued isolation of all these countries that
+similar forms (descendants of ancient types) are preserved in them. Had the
+numerous suggested continental extensions connecting these remote
+continents at various geological periods been realities, the result would
+have been that all these interesting archaic forms, all these defenceless
+insular types, would long ago have been exterminated, and one comparatively
+monotonous fauna have reigned over the whole earth. So far from explaining
+the anomalous facts, the alleged continental extensions, had they existed,
+would have left no such facts to be explained.
+
+ * * * * *
+
+
+{450}
+
+CHAPTER XX
+
+ANOMALOUS ISLANDS: CELEBES
+
+ Anomalous Relations of Celebes--Physical Features of the
+ Island--Zoological Character of the Islands Around Celebes--The Malayan
+ and Australian Banks--Zoology of Celebes: Mammalia--Probable Derivation
+ of the Mammals of Celebes--Birds of Celebes--Bird-types Peculiar to
+ Celebes--Celebes not Strictly a Continental Island--Peculiarities of
+ the Insects of Celebes--Himalayan Types of Birds and Butterflies in
+ Celebes--Peculiarities of Shape and Colour of Celebesian
+ Butterflies--Concluding Remarks--Appendix on the Birds of Celebes.
+
+The only other islands of the globe which can be classed as "ancient
+continental" are the larger Antilles (Cuba, Haiti, Jamaica, and Porto
+Rico), Iceland, and perhaps Celebes. The Antilles have been so fully
+discussed and illustrated in my former work, and there is so little fresh
+information about them, that I do not propose to treat of them here,
+especially as they fall short of Madagascar in all points of biological
+interest, and offer no problems of a different character from such as have
+already been sufficiently explained.
+
+Iceland, also, must apparently be classed as belonging to the "Ancient
+Continental Islands," for though usually described as wholly volcanic, it
+is, more probably, an island of varied geological structure buried under
+the lavas of its numerous volcanoes. But of late years extensive Tertiary
+deposits of Miocene age have been discovered, showing that it is not a mere
+congeries of {451} volcanoes; it is connected with the British Islands and
+with Greenland by seas less than 500 fathoms deep; and it possesses a few
+mammalia, one of which is peculiar, and at least three peculiar species of
+birds. It was therefore almost certainly united with Greenland, and
+probably with Europe by way of Britain, in the early part of the Tertiary
+period, and thus afforded one of the routes by which that intermigration of
+American and European animals and plants was effected which we know
+occurred during some portion of the Eocene and Miocene periods, and
+probably also in the Pliocene. The fauna and flora of this island are,
+however, so poor, and offer so few peculiarities, that it is unnecessary to
+devote more time to their consideration.
+
+There remains the great Malay island--Celebes, which, owing to its
+possession of several large and very peculiar mammalia, must be classed,
+zoologically, as "ancient continental"; but whose central position and
+relations both to Asia and to Australia render it very difficult to decide
+in which of the primary zoological regions it ought to be placed, or
+whether it has ever been united with either of the great continents.
+Although I have pretty fully discussed its zoological peculiarities and
+past history in my _Geographical Distribution of Animals_, it seems
+advisable to review the facts on the present occasion, more especially as
+the systematic investigation of the characteristics of continental islands
+we have now made will place us in a better position for determining its
+true zoo-geographical relations.
+
+_Physical Features of Celebes._--This large and still comparatively
+unexplored island is interesting to the geographer on account of its
+remarkable outline, but much more so to the zoologist for its curious
+assemblage of animal forms. The geological structure of Celebes is almost
+unknown. The extremity of the northern peninsula is volcanic; while in the
+southern peninsula there are extensive deposits of a crystalline limestone,
+in some places overlying basalt. Gold is found in the northern peninsula
+and in the central mass, as well as iron, tin, and copper in small
+quantities; so that there can be little {452} doubt that the mountain
+ranges of the interior consist of ancient stratified rocks.
+
+[Illustration: MAP OF CELEBES AND THE SURROUNDING ISLANDS.
+
+The depth of sea is shown by three tints: the lightest indicating less than
+100 fathoms, the medium tint less than 1,000 fathoms, and the dark tint
+more than 1,000 fathoms. The figures show depths in fathoms.]
+
+It is not yet known whether Celebes is completely separated from the
+surrounding islands by a deep sea, but {453} the facts at our command
+render it probable that it is so. The northern and eastern portions of the
+Celebes Sea have been ascertained to be from 2,000 to 2,600 fathoms deep,
+and such depths may extend over a considerable portion of it, or even be
+much exceeded in the centre. In the Molucca passage a single sounding on
+the Gilolo side gave 1,200 fathoms, and a large part of the Molucca and
+Banda Seas probably exceed 2,000 fathoms. The southern portion of the
+Straits of Macassar is full of coral reefs, and a shallow sea of less than
+100 fathoms extends from Borneo to within about forty miles of the western
+promontory of Celebes; but farther north there is deep water close to the
+shore, and it seems probable that a deep channel extends quite through the
+straits, which have no doubt been much shallowed by the deposits from the
+great Bornean rivers as well as by those of Celebes itself. Southward
+again, the chain of volcanic islands from Bali to Timor appears to rise out
+of a deep ocean, the few soundings we possess showing depths of from 670 to
+1,300 fathoms almost close to their northern shores. We seem justified,
+therefore, in concluding that Celebes is entirely surrounded by a deep sea,
+which has, however, become partially filled up by river deposits, by
+volcanic upheaval, or by coral reefs. Such shallows, where they exist, may
+therefore be due to antiquity and isolation, instead of being indications
+of a former union with any of the surrounding islands.
+
+_Zoological Character of the Islands around Celebes._--In order to have a
+clear conception of the peculiar character of the Celebesian fauna, we must
+take into account that of the surrounding countries from which we may
+suppose it to have received immigrants. These we may divide broadly into
+two groups, those on the west belonging to the Oriental region of our
+zoological geography, and those on the east belonging to the Australian
+region. Of the first group Borneo is a typical representative; and from its
+proximity and the extent of its opposing coasts it is the island which we
+should expect to show most resemblance to Celebes. We have already seen
+that the fauna of Borneo is essentially the same as that of Southern Asia,
+and that it is excessively rich in all the Malayan types of {454} mammalia
+and birds. Java and Bali closely resemble Borneo in general character,
+though somewhat less rich and with several peculiar forms; while the
+Philippine Islands, though very much poorer, and with a greater amount of
+speciality, yet exhibit essentially the same character. These islands,
+taken as a whole, may be described as having a fauna almost identical with
+that of Southern Asia; for no family of mammalia is found in the one which
+is absent from the other, and the same may be said, with very few and
+unimportant exceptions, of the birds; while hundreds of genera and of
+species are common to both.
+
+In the islands east and south of Celebes--the Moluccas, New Guinea, and the
+Timor group from Lombok eastward--we find, on the other hand, the most
+wonderful contrast in the forms of life. Of twenty-seven families of
+terrestrial mammals found in the great Malay islands, all have disappeared
+but four, and of these it is doubtful whether two have not been introduced
+by man. We also find here four families of Marsupials, all totally unknown
+in the western islands. Even birds, though usually more widely spread, show
+a corresponding difference, about eleven Malayan families being quite
+unknown east of Celebes, where six new families make their appearance which
+are equally unknown to the westward.[115]
+
+We have here a radical difference between two sets of islands not very far
+removed from each other, the one set belonging zoologically to Asia, the
+other to Australia. The Asiatic or Malayan group is found to be bounded
+strictly by the eastward limits of the great bank (for the most part less
+than fifty fathoms below the surface) which {455} stretches out from the
+Siamese and Malayan peninsula as far as Java, Sumatra, Borneo, and the
+Philippines. To the east another bank unites New Guinea and the Papuan
+Islands as far as Aru, Mysol, and Waigiou, with Australia; while the
+Moluccas and Timor groups are surrounded by much deeper water, which forms,
+in the Banda and Celebes Seas and perhaps in other parts of this area,
+great basins of enormous depths (2,000 to 3,000 fathoms or even more)
+enclosed by tracts under a thousand fathoms, which separate the basins from
+each other and from the adjacent Pacific and Indian Oceans (see map). This
+peculiar formation of the sea-bottom probably indicates that this area has
+been the seat of great local upheavals and subsidences; and it is quite in
+accordance with this view that we find the Moluccas, while closely agreeing
+with New Guinea in their forms of life, yet strikingly deficient in many
+important groups, and exhibiting an altogether poverty-stricken appearance
+as regards the higher animals. It is a suggestive fact that the Philippine
+Islands bear an exactly parallel relation to Borneo, being equally
+deficient in many of the higher groups; and here too, in the Sooloo Sea, we
+find a similar enclosed basin of great depth. Hence we may in both cases
+connect, on the one hand, the extensive area of land-surface and of
+adjacent shallow sea with a long period of stability and a consequent rich
+development of the forms of life; and, on the other hand, a highly broken
+land-surface with the adjacent seas of great but very unequal depths, with
+a period of disturbance, probably involving extensive submersions of the
+land, resulting in a scanty and fragmentary vertebrate fauna.
+
+_Zoology of Celebes._--The zoology of Celebes differs so remarkably from
+that of both the great divisions of the Archipelago above indicated, that
+it is very difficult to decide in which to place it. It possesses only
+about sixteen species of terrestrial mammalia, so that it is at once
+distinguished from Borneo and Java by its extreme poverty in this class. Of
+this small number four belong to the Moluccan and Australian fauna--there
+being two marsupials of the genus Cuscus, and two forest rats said to be
+allied to Australian types. {456}
+
+The remaining twelve species are, generally speaking, of Malayan or Asiatic
+types, but some of them are so peculiar that they have no near allies in
+any part of the world; while the rest are of the ordinary Malay type or
+even identical with Malayan species, and some of these may be recent
+introductions through human agency. These twelve species of Asiatic type
+will be now enumerated. They consist of five peculiar squirrels--a group
+unknown farther east; a peculiar species of wild pig; a deer so closely
+allied to the _Cervus hippelaphus_ of Borneo that it may well have been
+introduced by man both here and in the Moluccas; a civet, _Viverra
+tangalunga_, common in all the Malay Islands, and also perhaps introduced;
+the curious Malayan tarsier (_Tarsius spectrum_) said to be only found in a
+small island off the coast;--and besides these, three remarkable animals,
+all of large size and all quite unlike anything found in the Malay Islands
+or even in Asia. These are a black and almost tailless baboon-like ape
+(_Cynopithecus nigrescens_); an antelopean buffalo (_Anoa depressicornis_),
+and the strange babirusa (_Babirusa alfurus_).
+
+None of these three animals last mentioned has any close allies elsewhere,
+and their presence in Celebes may be considered the crucial fact which must
+give us the clue to the past history of the island. Let us then see what
+they teach us. The ape is apparently somewhat intermediate between the
+great baboons of Africa and the short-tailed macaques of Asia, but its
+cranium shows a nearer approach to the former group, in its flat projecting
+muzzle, large superciliary crests, and maxillary ridges. The anoa, though
+anatomically allied to the buffaloes, externally more resembles the bovine
+antelopes of Africa; while the babirusa is altogether unlike any other
+living member of the swine family, the canines of the upper jaws growing
+directly upwards like horns, forming a spiral curve over the eyes, instead
+of downwards, as in all other mammalia. An approach to this peculiarity is
+made by the African wart-hogs, in which the upper tusk grows out laterally
+and then curves up; but these animals are not otherwise closely allied to
+the babirusa. {457}
+
+_Probable Derivation of the Mammals of Celebes._--It is clear that we have
+here a group of extremely peculiar, and, in all probability, very ancient
+forms, which have been preserved to us by isolation in Celebes, just as the
+monotremes and marsupials have been preserved in Australia, and so many of
+the lemurs and Insectivora in Madagascar. And this compels us to look upon
+the existing island as a fragment of some ancient land, once perhaps
+forming part of the great northern continent, but separated from it far
+earlier than Borneo, Sumatra, and Java. The exceeding scantiness of the
+mammalian fauna, however, remains to be accounted for. We have seen that
+Formosa, a much smaller island, contains more than twice as many species;
+and we may be sure that at the time when such animals as apes and buffaloes
+existed, the Asiatic continent swarmed with varied forms of mammals to
+quite as great an extent as Borneo does now. If the portion of separated
+land had been anything like as large as Celebes now is, it would certainly
+have preserved a far more abundant and varied fauna. To explain the facts
+we have the choice of two theories:--either that the original island has
+since its separation been greatly reduced by submersion, so as to lead to
+the extinction of most of the higher land animals; or, that it originally
+formed part of an independent land stretching eastward, and was only united
+with the Asiatic continent for a short period, or perhaps even never united
+at all, but so connected by intervening islands separated by narrow straits
+that a few mammals might find their way across. The latter supposition
+appears best to explain the facts. The three animals in question are such
+as might readily pass over narrow straits from island to island; and we are
+thus better enabled to understand the complete absence of the arboreal
+monkeys, of the Insectivora, and of the very numerous and varied Carnivora
+and Rodents of Borneo, all of which except the squirrels are entirely
+unrepresented in Celebes by any peculiar and ancient forms.
+
+The question at issue can only be finally determined by geological
+investigations. If Celebes has once formed part of Asia, and participated
+in its rich mammalian fauna, which has been since destroyed by submergence,
+then some {458} remains of this fauna must certainly be preserved in caves
+or late Tertiary deposits, and proofs of the submergence itself will be
+found when sought for. If, on the other hand, the existing animals fairly
+represent those which have ever reached the island, then no such remains
+will be discovered, and there need be no evidence of any great and
+extensive subsidence in late Tertiary times.
+
+_Birds of Celebes._--Having thus clearly placed before us the problem
+presented by the mammalian fauna of Celebes, we may proceed to see what
+additional evidence is afforded by the birds and any other groups of which
+we have sufficient information. About 164 species of true land-birds are
+now known to inhabit the island of Celebes itself. Considerably more than
+half of these (ninety-four species) are peculiar to it; twenty-nine are
+found also in Borneo and the other Malay Islands, to which they specially
+belong; while sixteen are common to the Moluccas or other islands of the
+Australian region; the remainder being species of wide range and not
+characteristic of either division of the Archipelago. We have here a large
+preponderance of western over eastern species of birds inhabiting Celebes,
+though not to quite so great an extent as in the mammalia; and the
+inference to be drawn from this fact is, simply, that more birds have
+migrated from Borneo than from the Moluccas--which is exactly what we might
+expect both from the greater extent of the coast of Borneo opposite that of
+Celebes, and also from the much greater richness in species of the Bornean
+than the Moluccan bird-fauna.
+
+It is, however, to the relations of the peculiar species of Celebesian
+birds that we must turn, in order to ascertain the origin of the fauna in
+past times; and we must look to the source of the generic types which they
+represent to give us this information. The ninety-four peculiar species
+above noted belong to about sixty-six genera, of which about twenty-three
+are common to the whole Archipelago, and have therefore little
+significance. Of the remainder, twelve are altogether peculiar to Celebes;
+twenty-one are Malayan, but not Moluccan or Australian; while ten are
+Moluccan or Australian, but not Malayan. This {459} proportion does not
+differ much from that afforded by the non-peculiar species; and it teaches
+us that, for a considerable period, Celebes has been receiving immigrants
+from all sides, many of which have had time to become modified into
+distinct representative species. These evidently belong to the period
+during which Borneo on the one side, and the Moluccas on the other, have
+occupied very much the same relative position as now. There remain the
+twelve peculiar Celebesian genera, to which we must look for some further
+clue as to the origin of the older portion of the fauna; and as these are
+especially interesting we must examine them somewhat closely.
+
+_Bird-types Peculiar to Celebes._--First we have Artamides, one of the
+Campephaginæ or caterpillar-shrikes--a not very well-marked genus, and
+which may have been derived, either from the Malayan or the Moluccan side
+of the Archipelago. Two peculiar genera of kingfishers--Monachalcyon and
+Cittura--seem allied, the former to the widespread Todiramphus and to the
+Caridonax of Lombok, the latter to the Australian Melidora. Another
+kingfisher, Ceycopsis, combines the characters of the Malayan Ceyx and the
+African Ispidina, and thus forms an example of an ancient generalised form
+analogous to what occurs among the mammalia. Streptocitta is a peculiar
+form allied to the magpies; while Basilornis (found also in Ceram), Enodes,
+and Scissirostrum, are very peculiar starlings, the latter altogether
+unlike any other bird, and perhaps forming a distinct sub-family. Meropogon
+is a peculiar bee-eater, allied to the Malayan Nyctiornis; Rhamphococyx is
+a modification of Phænicophaes, a Malayan genus of cuckoos; Prioniturus
+(found also in the Philippines) is a genus of parrots distinguished by
+raquet-formed tail feathers, altogether unique in the order; while
+Megacephalon is a remarkable and very isolated form of the Australian
+Megapodiidæ, or mound-builders.
+
+Omitting those whose affinity may be pretty clearly traced to groups still
+inhabiting the islands of the western or the eastern half of the
+Archipelago, we find four birds which have no near allies at all, but
+appear to be either ancestral forms, or extreme modifications, of Asiatic
+or {460} African birds--Basilornis, Enodes, Scissirostrum, Ceycopsis. These
+may fairly be associated with the baboon-ape, anoa, and babirusa, as
+indicating extreme antiquity and some communication with the Asiatic
+continent at a period when the forms of life and their geographical
+distribution differed considerably from what they are at the present time.
+
+But here again we meet with exactly the same difficulty as in the mammalia,
+in the comparative poverty of the types of birds now inhabiting Celebes.
+Although the preponderance of affinity, especially in the case of its more
+ancient and peculiar forms, is undoubtedly with Asia rather than with
+Australia; yet, still more decidedly than in the case of the mammalia, are
+we forbidden to suppose that it ever formed a part of the old Asiatic
+continent, on account of the _total_ absence of so many important and
+extensive groups of Asiatic birds. It is not single species or even genera,
+but whole families that are thus absent, and among them families which are
+pre-eminently characteristic of all tropical Asia. Such are the Timaliidæ,
+or babblers, of which there are twelve genera in Borneo, and nearly thirty
+genera in the Oriental Region, but of which one species only, hardly
+distinguishable from a Malayan form, inhabits Celebes; the Phyllornithidæ,
+or green bulbuls, and the Pycnonotidæ, or bulbuls, both absolutely
+ubiquitous in tropical Asia and Malaya, but unknown in Celebes; the
+Eurylæmidæ, or gapers, found everywhere in the great Malay Islands; the
+Megalæmidæ, or barbets; the Trogonidæ, or trogons; and the Phasianidæ, or
+pheasants, all pre-eminently Asiatic and Malayan but all absent from
+Celebes, with the exception of the common jungle-fowl, which, owing to the
+passion of Malays for cock-fighting, may have been introduced. To these
+important _families_ may be added Asiatic and Malayan _genera_ by the
+score; but, confining ourselves to these seven ubiquitous families, we must
+ask,--Is it possible, that, at the period when the ancestors of the
+peculiar Celebes mammals entered the island, and when the forms of life,
+though distinct, could not have been quite unlike those now living, it
+could have actually formed a part of the continent without {461} possessing
+representatives of the greater part of these extensive and important
+families of birds? To get rid altogether of such varied and dominant types
+of bird-life by any subsequent process of submersion is more difficult than
+to exterminate mammalia; and we are therefore again driven to our former
+conclusion--that the present land of Celebes has never (in Tertiary times)
+been united to the Asiatic continent, but has received its population of
+Asiatic forms by migration across narrow straits and intervening islands.
+Taking into consideration the amount of affinity on the one hand, and the
+isolation on the other, of the Celebesian fauna, we may probably place the
+period of this earlier migration in the early part of the latter half of
+the Tertiary period, that is, in middle or late Miocene times.
+
+_Celebes not Strictly a Continental Island._--A study of the mammalian and
+of the bird-fauna of Celebes thus leads us in both cases to the same
+conclusion, and forbids us to rank it as a strictly continental island on
+the Asiatic side. But facts of a very similar character are equally opposed
+to the idea of a former land-connection with Australia or New Guinea, or
+even with the Moluccas. The numerous marsupials of those countries are all
+wanting in Celebes, except the phalangers of the genus Cuscus, and these
+arboreal creatures are very liable to be carried across narrow seas on
+trees uprooted by earthquakes or floods. The terrestrial cassowaries are
+equally absent; and thus we can account for the presence of all the
+Moluccan or Australian types actually found in Celebes without supposing
+any land-connection on this side during the Tertiary period. The presence
+of the Celebes ape in the island of Batchian, and of the babirusa in Bouru,
+can be sufficiently explained by a somewhat closer approximation of the
+respective lands, or by a few intervening islands which have since
+disappeared, or it may even be due to human agency.
+
+If the explanation now given of the peculiar features presented by the
+fauna of Celebes be the correct one, we are fully justified in classing it
+as an "anomalous island," since it possesses a small but very remarkable
+mammalian fauna, without ever having been directly united with any {462}
+continent or extensive land; and, both by what it has and what it wants,
+occupies such an exactly intermediate position between the Oriental and
+Australian regions that it will perhaps ever remain a mere matter of
+opinion with which it should properly be associated. Forming, as it does,
+the western limit of such typical Australian groups as the Marsupials among
+mammalia, and the Trichoglossidæ and Meliphagidæ among birds, and being so
+strikingly deficient in all the more characteristic Oriental families and
+genera of both classes, I have always placed it in the Australian Region;
+but it may perhaps with equal propriety be left out of both till a further
+knowledge of its geology enables us to determine its early history with
+more precision.
+
+_Peculiarities of the Insects of Celebes._--The only other class of animals
+in Celebes, of which we have a tolerable knowledge, is that of insects,
+among which we meet with peculiarities of a very remarkable kind, and such
+as are found in no other island on the globe. Having already given a full
+account of some of these peculiarities in a paper read before the Linnean
+Society--republished in my _Contributions to the Theory of Natural
+Selection_,--while others have been discussed in my _Geographical
+Distribution of Animals_ (Vol. I. p. 434)--I will only here briefly refer
+to them in order to see whether they accord with, or receive any
+explanation from, the somewhat novel view of the past history of the island
+here advanced.
+
+The general distribution of the two best known groups of insects--the
+butterflies and the beetles--agrees very closely with that of the birds and
+mammalia, inasmuch as Celebes forms the eastern limit of a number of
+Asiatic and Malayan genera, and at the same time the western limit of
+several Moluccan and Australian genera, the former perhaps preponderating
+as in the higher animals.
+
+_Himalayan Types of Birds and Butterflies in Celebes._--A curious fact of
+distribution exhibited both among butterflies and birds, is the occurrence
+in Celebes of species and genera unknown to the adjacent islands, but only
+found again when we reach the Himalayan mountains or the Indian Peninsula.
+Among birds we have a small yellow {463} flycatcher (_Myialestes
+helianthea_), a flower-pecker (_Pachyglossa aureolimbata_), a finch (_Munia
+brunneiceps_), and a roller (_Coracias temminckii_), all closely allied to
+Indian (not Malayan) species,--all the genera, except Munia, being, in
+fact, unknown in any Malay island. An exactly parallel case is that of a
+butterfly of the genus Dichorrhagia, which has a very close ally in the
+Himalayas, but nothing like it in any intervening country. These facts call
+to mind the similar case of Formosa, where some of its birds and mammals
+occurred again, under identical or closely allied forms, in the Himalayas;
+and in both instances they can only be explained by going back to a period
+when the distribution of these forms was very different from what it is
+now.
+
+_Peculiarities of Shape and Colour in Celebesian Butterflies._--Even more
+remarkable are the peculiarities of shape and colour in a number of
+Celebesian butterflies of different genera. These are found to vary all in
+the same manner, indicating some general cause of variation able to act
+upon totally distinct groups, and produce upon them all a common result.
+Nearly thirty species of butterflies, belonging to three different
+families, have a common modification in the shape of their wings, by which
+they can be distinguished at a glance from their allies in any other island
+or country whatever; and all these are larger than the representative forms
+inhabiting most of the adjacent islands.[116] No such remarkable local
+modification as this is known to occur in any other part of the globe; and
+whatever may have been its cause, that cause must certainly have been long
+in action, and have been confined to a limited area. We have here,
+therefore, another argument in favour of the long-continued isolation of
+Celebes from all the surrounding islands and continents--a hypothesis which
+we have seen to afford the best, if not the only, explanation of its
+peculiar vertebrate fauna.
+
+_Concluding Remarks._--If the view here given of the origin of the
+remarkable Celebesian fauna is correct, we have in this island a fragment
+of the great eastern {464} continent which has preserved to us, perhaps
+from Miocene times, some remnants of its ancient animal forms. There is no
+other example on the globe of an island so closely surrounded by other
+islands on every side, yet preserving such a marked individuality in its
+forms of life; while, as regards the special features which characterise
+its insects, it is, so far as yet known, absolutely unique. Unfortunately
+very little is known of the botany of Celebes, but it seems probable that
+its plants will to some extent partake of the speciality which so markedly
+distinguishes its animals; and there is here a rich field for any botanist
+who is able to penetrate to the forest-clad mountains of its interior.
+{465}
+
+APPENDIX TO CHAPTER XX
+
+The following list of the Land Birds of Celebes and the adjacent islands
+which partake of its zoological peculiarities, in which are incorporated
+all the species discovered up to 1890, has been drawn up from the following
+sources:--
+
+ 1. A List of the Birds known to inhabit the Island of Celebes, By
+ Arthur, Viscount Walden, F.R.S. (Trans. Zool. Soc. 1872. Vol. viii. pt.
+ ii.)
+
+ 2. Intorno al Genere Hermotimia. (Rchb.) Nota di Tommaso Salvadori.
+ (Atti della Reale Accademia delle Scienze di Torino. Vol x. 1874.)
+
+ 3. Intorno a due Collezioni di Ucelli di Celebes--Note di Tommaso
+ Salvadori. (Annali del Mus. Civ. di St. Nat. di Genova. Vol. vii.
+ 1875.)
+
+ 4. Beiträge zur Ornithologie von Celebes und Sangir. Von Dr. Friedrich
+ Brüggemann. Bremen, 1876.
+
+ 5. Intorno a due piccole Collezioni di Ucelli di Isole Sanghir e di
+ Tifore. Nota di Tommaso Salvadori. (Annali del Mus. Civ. di St. Nat. di
+ Genova. Vol. ix. 1876-77.)
+
+ 6. Intorno alle Specie di Nettarinie delle Molucche e del Gruppo di
+ Celebes. Note di Tommaso Salvadori. (Atti della Reale Accad. delle
+ Scienze di Torino. Vol. xii. 1877.)
+
+ 7. Descrizione di tre Nuove Specie di Ucelli, e note intorno ad altre
+ poco conosciute delle Isole Sanghir. Per Tommaso Salvadori. (L. c. Vol.
+ xiii. 1878.)
+
+ 8. Field Notes on the Birds of Celebes. By A. B. Meyer, M.D., &c.
+ (Ibis, 1879.)
+
+ 9. On the Collection of Birds made by Dr. Meyer during his Expedition
+ to New Guinea and some neighbouring Islands. By R. Boulder Sharpe.
+ (Mitth. d. kgl. Zool. Mus. Dresden, 1878. Heft 3.) New species from the
+ Sula and Sanghir Islands are described.
+
+ 10. List of Birds from the Sula Islands (East of Celebes) with
+ Descriptions of the New Species. By Alfred Russel Wallace, F.Z.S.
+ (_Proc. Zool. Soc._ 1862, p. 333.)
+
+ 11. The Zoological Record, and "The Ibis" to 1890.
+
+{466}
+
+LIST OF LAND BIRDS OF CELEBES
+
+_N.B.--The Species marked with an * are not included in Viscount Walden's
+list. For these only, an authority is usually given._
+
+ --------------------------------+-------+-------+-------+-------------
+ |Celebes| Sula |Sanghir| Range and
+ | | Is. | Is. | Remarks
+ --------------------------------+-------+-------+-------+-------------
+ TURDIDÆ. | | | |
+ 1. Geocichla erythronota | X | | |
+ 2. Monticola solitaria | X | | X |Phil., China,
+ | | | | Japan
+ | | | |
+ SYLVIIDÆ. | | | |
+ 3. Cisticola cursitans | X | | |Assam
+ 4 ,, grayi | X | | |
+ 5. Acrocephalus orientalis | X | | |China, Japan
+ *6. ,, insularis | -- | -- | X |Moluccas
+ | | |(Salv.)|
+ 7. Pratincola caprata | X | | |Asia, Java,
+ | | | | Timor
+ *8. Gerygone flaveola (Cab.) | X | | |(Near G.
+ |(Meyer)| | |_sulphurea_,
+ | | | |Timor)
+ | | | |
+ TIMALIIDÆ. | | | |
+ 9. Trichostoma celebense | X | | |
+ | | | |
+ PYCNONOTIDÆ. | | | |
+ *10. Criniger longirostris | | | |
+ (Wall.) | | X | |Oriental
+ | | | | genus (near
+ | | | | Bouru sp.)
+ 11. ,, aureus (Wald.) | X | | |
+ | | | |
+ ORIOLIDÆ. | | | |
+ 12. Oriolus celebensis | X | | |(Var of O.
+ | | | | _coronatus_,
+ | | | | Java)
+ 13. ,, formosus (Cab.) | -- | -- | X |(Var. of
+ | | |(Brugg.) Philipp.
+ | | | | sp.)
+ 14. ,, frontalis (Wall.) | -- | X | |
+ | | | |
+ CAMPEPHAGIDÆ. | | | |
+ 15. Graucalus atriceps | X | | |Ceram, Flores
+ 16. ,, leucopygius | X | | |
+ 17. ,, temminckii | X | X | |
+ 18. Campephaga morio | X | | |
+ *19. ,, melanotis | -- | X | |Moluccas
+ *20. ,, salvadorii | |(Wall.)| |
+ (Sharpe) | -- | -- | X |
+ 21. Lalage leucopygialis | X | | |
+ *22. ,, dominica | X | -- | -- |Java
+ |(Meyer)| | |
+ 23. Artamides bicolor | X | | |
+ *24. ,, schistaceus | | | |
+ (Sharpe) | -- | X | |
+ | | | |
+ DICRURIDÆ. | | | |
+ 25. Dicrurus leucops | X | | |
+ *26. ,, axillaris (Salv.) | -- | -- | X |
+ *27. ,, pectoralis (Wall.) | | X | |
+ {467}
+ | | | |
+ MUSCICAPIDÆ. | | | |
+ 28. Cyornis rufigula | X | | |
+ 29. ,, banyumas | X | | |Java and Borneo
+ 30. Myialestes helianthea | X | | |(Indian ally)
+ 31. Hypothymis puella | X | X | |
+ 32. ,, menadensis? | X | | |
+ *33. Monarcha commutata | | | |
+ (Brugg.) | X | | |
+ *34. ,, cinerascens | -- | X | |Moluccas
+ | |(Wall.)| |
+ PACHYCEPHALIDÆ. | | | |
+ 35. Hylocharis sulfuriventra | X | | |
+ *36. Pachycephala lineolata | | | |
+ (Wall.) | -- | X | -- |Bouru
+ *37. Pachycephala rufescens | | | |
+ (Wall.) | -- | X | -- |Bouru
+ *38. Pachycephala clio (Wall.) | -- | X | -- |Bouru
+ | | | |
+ LANIIDÆ. | | | |
+ *39. Lanius magnirostris (Meyer)| X | -- | -- |Java
+ | | | |
+ CORVIDÆ. | | | |
+ 40. Corvus enca | X | X var.| |Java
+ *41. ,, annectens (Brugg.) | X | | |
+ 42. ,,(Gazzola) typica | X | | |
+ 43. Streptocitta caledonica | X | | |
+ 44. ,, torquata | X | | |
+ *45(Charitornis) albertiæ(Schl.)| -- | X | |
+ | | | |
+ MELIPHAGIDÆ. | | | |
+ 46. Myzomela chloroptera | X | | |(Nearest _M.
+ | | | |sanguinolenta_
+ | | | |of Australia)
+ NECTARINIIDÆ. | | | |
+ 47. Anthreptes celebensis | | | |
+ (Shelley) | X | X | X |Siam, Malaya
+ 48. Chalcostethia porphyolæma | X | | |
+ *49. ,, auriceps | -- | X | -- |Ternate
+ | |(Wall.)| |
+ *50. ,, sangirensis | -- | -- | X |
+ (Meyer) | | | |
+ 51. Cyrtostomus frenatus | X | X | -- |Moluccas and N.
+ | | | | Guinea
+ 52. Nectarophila grayi | X | | |
+ 53. Æthopyga flavostriata | X | | |(An Oriental
+ | | | | genus)
+ *54. ,, beccarii (Salv.) | X | | |
+ *55. ,, duyvenbodei (Schl.)| -- | -- | X |
+ | | | |
+ DICÆIDÆ. | | | |
+ 56. Zosterops intermedia | X | | |Lombock
+ 57. ,, atrifrons | X | | |
+ 58. Dicæum celebicum | X | X | |
+ *59. ,, sanghirense (Salv.) | -- | -- | X |
+ *60. ,, nehrkorni (Blas.) | X | | |
+ 61. Pachyglossa aureolimbata | X | -- | X |
+ | | | |
+ HIRUNDINIDÆ. | | | |
+ 62. Hirundo gutturalis | X | | X |Indian region
+ 63. ,, javanica | X | X | |Indo-Malaya
+ | | | |
+ PLOCEIDÆ. | | | |
+ 64. Munia oryzivora | X | | |Java
+ 65. ,, nisoria | X | | |Java
+ 66. ,, molucca | X | | |Moluccas
+ {468}
+ 67. ,, brunneiceps | X | | |(Near _M.
+ | | | |rubronigra_,
+ | | | |India)
+ *68. ,, jagori | X | | |Philippines
+ |(Meyer)| | |
+ STURNIDÆ. | | | |
+ 69. Basilornis celebensis | X | | |
+ 70. Acridotheres cinereus | X | | |
+ 71. Sturnia pyrrhogenys | X | | |Malaya
+ 72. Calornis neglecta | X | X | X var.|
+ *73. ,, metallica | X | X | |Moluccas
+ |(Brugg.)(Wall.)| |
+ 74. Enodes crythrophrys | X | | |
+ 75. Scissirostrum pagei | X | | |
+ | | | |
+ ARTAMIDÆ. | | | |
+ 76. Artamus monachus | X | X | |
+ 77. ,, leucorhynchus | X | | |Malay Archipel.
+ | | | |
+ MOTACILLIDÆ. | | | |
+ 78. Corydalla gustavi | X | | |
+ 79. Budytes viridis | X | | |Java, Moluccas
+ *80. Calobates melanope | | | |
+ (= Motac. sulfurea, Brugg.) | X | | |China, Phillipp.
+ | | | |
+ PITTIDÆ. | | | |
+ 81. Pitta forsteni | X | | |
+ *82. ,, sanghirana (Schl.) | | | X |
+ 83. ,, celebensis | X | | |
+ *84. ,, palliceps (Brugg.) | | | X |
+ *85. ,, coeruleitorques (Salv.) | | X |
+ *86. ,, irena (= crassirostris) | X | |Timor, Ternate?
+ | |(Wall.)| |
+ PICIDÆ. | | | |
+ 87. Alophonerpes fulvus | X | | |
+ *88. ,, wallacei | | | |
+ 89. Yungipicus temminckii | X | | |
+ | | | |
+ CUCULIDÆ. | | | |
+ 90. Rhamphococcyx calorhynchus | X | | |
+ 91. Pyrrhocentor celebensis | X | | |
+ 92. Centropus affinis | X | | |Java
+ 93. ,, javanensis | X | | |Java, Borneo
+ 94. Cuculus canorus | X | | |
+ 95. Cacomantes lanceolatus | X | | |Java
+ 96. ,, sepulchralis | X | | |
+ 97. Hierococcyx crassirostris | X | | |
+ 98. Eudynamis melanorhyncha | X | | |
+ *99. ,, facialis (Wall.) | | X | |
+ *100. ,, orientalis | | | X |Moluccas?
+ | | |(Brugg.)
+ 101. Scythrops novæhollandiæ | X | | |Moluccas, &c.
+ | | | |
+ CORACIIDÆ. | | | |
+ 102. Coracias temminckii | X | | |
+ 103. Eurystomus orientalis | X | X | X |Asia
+ | | | |
+ MEROPIDÆ. | | | |
+ 104. Meropogon forsteni | X | | |
+ 105. Merops philippinus | X | | |Oriental region
+ 106. ,, ornatus | X | X | |Java, Australia
+ | | | |
+ ALCEDINIDÆ. | | | |
+ 107. Alcedo moluccensis | X | | X |Moluccas
+ 108. ,, asiatica | X | | |Indo-Malaya
+ {469}
+ 109. Pelargopsis melanorhyncha | X | X | |
+ *110. Ceyx wallacei (Sharpe) | | X | |(Allied to Mol.
+ | | | | sp.)
+ 111. Ceycopsis fallax | X | | |
+ 112. Halcyon chloris | X | X | X |All Archipel.
+ 113. ,, sancta | X | X | |All Archipel.
+ 114. ,, forsteni | X | | |
+ 115. ,, rufa | X | X | |
+ 116. Monachalcyon princeps | X | | |
+ *117. ,, cyanocephala (Brugg.) | X | | |
+ 118. Cittura cyanotis | X | | |
+ *119. ,, sanghirensis (Schl.)| | | X |
+ | | | |
+ BUCEROTIDÆ. | | | |
+ 120. Hydrocissa exarata | X | | |
+ 121. Cranorhinus cassidix | X | | |
+ | | | |
+ CAPRIMULGIDÆ. | | | |
+ 122. Caprimulgus affinis | X | | |
+ 123. ,, sp. | X | | |
+ 124. Lyncornis macropterus. | X | | |
+ | | | |
+ CYPSELIDÆ. | | | |
+ 125. Dendrochelidon wallacei | X | X | |
+ 126. Collocalia esculenta | X | | |Mol. to Arn Is.
+ 127. ,, fuciphaga | X | | |India, Java
+ 128. Chætura gigantea | X | | |India, Java
+ | | | |
+ PSITTACI. | | | |
+ 129. Cacatua sulphurea | X | | |Lombock, Flores
+ 130. Prioniturus platurus | X | | |
+ 131. ,, flavicans | X | | |
+ *132. Platycercus dorsalis, var.| | X | |N. Guinea?
+ | |(Wall.)| |
+ 133. Tanygnathus mulleri | X | X | |
+ *134. ,, megalorhynchus | X | | X |Moluccas. An
+ | | | |island near
+ | | | |Menado (Meyer)
+ *135. ,, luzoniensis | | | X |
+ | | |(Brugg.)
+ 136. Loriculus stigmatus | X | | |
+ *137. ,, quadricolor (Wald.)| X | | |Togian Is., Gulf
+ | | | |of Tomini
+ 138. ,, sclateri | ? | X | |
+ 139. ,, exilis | X | | |
+ *140. ,, catamene (Schl.) | | | X |
+ 141. Trichoglossus ornatus | X | | |
+ *142. ,, flavoviridis (Wall.)| | X | |
+ 143. ,, meyeri | X | | |
+ *144. Eos histrio = E. coccinea | | | X |
+ | | | |
+ COLUMBÆ. | | | |
+ 145. Treron vernans | X | | |Malacca, Java,
+ | | | |Philipp.
+ 146. ,, griseicauda | X | X | X var.|
+ | | |Sanghir-
+ | | | ensis |
+ 147. Ptilopus formosus | X | | |
+ 148. ,, melanocephalus | X | X | X var.|Java, Lombock
+ | | |Xantho-|
+ | | | rrhoa,|
+ | | |Salv. |
+ 149. ,, gularis | X | | |
+ *150. ,, fischeri (Brugg.)| X | | |
+ 151. Carpophaga paulina | X | X | |
+ {470}
+ *152. ,, pulchella | X | | |Togian Is.
+ (Wald.) | | | |(_Ann. and
+ | | | |Mag. Nat. Hst._,
+ | | | |1874.)
+ 153. ,, concinna | | | X |Ké Goram
+ | | |(Salv.)|
+ 154. ,, rosacea | X | | |Gilolo, Timor
+ *155. ,, pæcilorrhoa (Brugg) | X | | |
+ 156. ,, luctuosa | X | X | |
+ *157. ,, bicolor | X | | X |New Guin.,
+ |(Meyer)| | |Moluccas
+ 158. ,, radiata | X | | X |
+ 159. ,, forsteni | X | | |
+ 160. Macropygia albicapilla | X | X | |
+ 161. ,, macassariensis | X | | |
+ *162. ,, sanghirensis (Salv.) | | | X |
+ 163. Turacoena menadensis | X | X | |
+ *164. Reinwardtænas reinwardti |X Meyer| | |Moluccas & New
+ | | | |Guin.
+ 165. Turtur tigrina | X | | |Malaya, Moluccas
+ 166. Chalcophaps stephani | X | | |New Guinea
+ 167. ,, indica | X | X var.| X |India and
+ | | | |Archipel.
+ 168. Phlogænas tristigmata | X | | |
+ 169. Geopelia striata | X | | |China, Java,
+ | | | |Lombock
+ 170. Calænas nicobarica | X | | |Malacca and New
+ | | | |Guinea
+ | | | |
+ GALLINÆ. | | | |
+ 171. Gallus bankiva | X | | |Java, Timor
+ 172. Coturnix minima | X | | |(Var. of _C.
+ | | | |Chinensis_)
+ 173. Turnix rufilatus | X | | |
+ *174. ,, beccarii (Salv.) | X | | |
+ 175. Megapodius gilberti | X | | |
+ 176. Megacephalon malleo | X | | X |
+ | | | |
+ ACCIPITRES. | | | |
+ 177. Circus assimilis | X | | |Australia
+ 178. Astur griseiceps | X | | |
+ *179. ,, tenuirostris (Brugg.) X | | |
+ 180. ,, rhodogastra | X | | |
+ 181. ,, trinotata | X | | |
+ 182. Accipiter sulaensis (Schl.) X | | |
+ 183. ,, soloensis | X | | |Malacca & New
+ | | | |Guin.
+ 184. Neopus malayensis | X | | |Nepaul, Sum.,
+ | | | |Java, Moluccas
+ 185. Spizaetus lanceolatus | X | X | |
+ 186. Haliactus leucogaster | X | | |Oriental region
+ 187. Spilornis rufipectus | X | X | |
+ 188. Butastur liventer | X | | |Java, Timor
+ 189. ,, indicus | X | | X |India, Java
+ 190. Haliastur leucosternus | X | | |Moluccas, New
+ | | | |Guin.
+ 191. Milvus affinis | X | | |Australia
+ 192. Elanus hypoleucus | X | | |? Java, Borneo
+ 193. Pernis ptilorhyncha (var. | | | |
+ celebensis) | X | | |(Var. Java, &c.)
+ 194. Baza erythrothorax | X | X | |
+ 195. Falco severus | X | | |All Archipel.
+ 196. Cerchneis moluccensis | X | | |Java, Moluccas
+ 197. Polioaetus humilis | X | | |India, Malaya
+ | | | |
+ STRIGIDÆ. | | | |
+ 198. Athene punctulata | X | | |
+ 199. ,, ochracea | X | | |
+ 200. Scops magicus | X | | |Amboyna, &c.?
+ 201. ,, menadensis | X | | |Flores,
+ | | | |Madagascar
+ 202. Ninox japonicus | X | | |China, Japan
+ *203. ,, scutulata | | | X |Malacca
+ | | |(Salv.)|
+ 204. Strix rosenbergi | X | | |
+ --------------------------------+-------+-------+-------+--------------------
+
+ * * * * *
+
+
+{471}
+
+CHAPTER XXI
+
+ANOMALOUS ISLANDS: NEW ZEALAND
+
+ Position and Physical Features of New Zealand--Zoological Character of
+ New Zealand--Mammalia--Wingless Birds Living and Extinct--Recent
+ Existence of the Moa--Past Changes of New Zealand deduced from its
+ Wingless Birds--Birds and Reptiles of New Zealand--Conclusions from the
+ Peculiarities of the New Zealand Fauna.
+
+The fauna of New Zealand has been so recently described, and its bearing on
+the past history of the islands so fully discussed in my large work already
+referred to, that it would not be necessary to introduce the subject again,
+were it not that we now approach it from a somewhat different point of
+view, and with some important fresh material, which will enable us to
+arrive at more definite conclusions as to the nature and origin of this
+remarkable fauna and flora. The present work is, besides, addressed to a
+wider class of readers than my former volumes, and it would be manifestly
+incomplete if all reference to one of the most remarkable and interesting
+of insular faunas was omitted.
+
+The two great islands which mainly constitute New Zealand are together
+about as large as the kingdom of Italy. They stretch over thirteen degrees
+of latitude in the warmer portion of the south-temperate zone, their
+extreme points corresponding to the latitudes of Vienna and Cyprus. Their
+climate throughout is mild and {472} equable, their vegetation is
+luxuriant, and deserts or uninhabitable regions are as completely unknown
+as in our own islands.
+
+The geological structure of these islands has a decidedly continental
+character. Ancient sedimentary rocks, granite, and modern volcanic
+formations abound; gold, silver, copper, tin, iron, and coal are plentiful;
+and there are also some considerable deposits of early or late Tertiary
+age. The Secondary rocks alone are very scantily developed, and such
+fragments as exist are chiefly of Cretaceous age, often not clearly
+separated from the succeeding Eocene beds.
+
+[Illustration: MAP SHOWING DEPTHS OF SEA AROUND AUSTRALIA AND NEW ZEALAND.]
+
+ The light tint indicates a depth of less than 1,000 fathoms.
+ The dark tint ,, ,, more than 1,000 fathoms.
+
+The position of New Zealand, in the great Southern Ocean, about 1,200 miles
+distant from the Australian {473} continent, is very isolated. It is
+surrounded by a moderately deep ocean; but the form of the sea-bottom is
+peculiar, and may help us in the solution of some of the anomalies
+presented by its living productions. The line of 200 fathoms encloses the
+two islands and extends their area considerably; but the 1,000-fathom line,
+which indicates the land-area that would be produced if the sea-bottom were
+elevated 6,000 feet, has a very remarkable conformation, extending in a
+broad mass westward and northward, then sending out a great arm reaching to
+beyond Lord Howe's Island. Norfolk Island is situated on a moderate-sized
+bank, while two others, much more extensive, to the north-west approach the
+great barrier reef, which here carries the 1,000-fathom line more than 300
+miles from the coast. It is probable that a bank, less than 1,500 fathoms
+below the surface, extends over this area, thus forming a connection with
+tropical Australia and New Guinea. Temperate Australia, on the other hand,
+is divided from New Zealand by an oceanic gulf about 700 miles wide and
+between 2,000 and 3,000 fathoms deep. The 2,000-fathom line embraces all
+the islands immediately round New Zealand as far as the Fijis to the north,
+while a submarine plateau at a depth somewhere between one and two thousand
+fathoms stretches southward to the Antarctic continent. Judging from these
+indications, we should say that the most probable ancient connections of
+New Zealand were with tropical Australia, New Caledonia, and the Fiji
+Islands, and perhaps at a still more remote epoch, with the great Southern
+continent by means of intervening lands and islands; and we shall find that
+a land-connection or near approximation in these two directions, at remote
+periods, will serve to explain many of the remarkable anomalies which these
+islands present.
+
+_Zoological Character of New Zealand._--We see, then, that both
+geologically and geographically New Zealand has more of the character of a
+"continental" than of an "oceanic" island, yet its zoological
+characteristics are such as almost to bring it within the latter
+category--and it is this which gives it its anomalous character. It is
+usually {474} considered to possess no indigenous mammalia; it has no
+snakes, and only one frog; it possesses (living or quite recently extinct)
+an extensive group of birds incapable of flight; and its productions
+generally are wonderfully isolated, and seem to bear no predominant or
+close relation to those of Australia or any other continent. These are the
+characteristics of an oceanic island; and thus we find that the inferences
+from its physical structure and those from its forms of life directly
+contradict each other. Let us see how far a closer examination of the
+latter will enable us to account for this apparent contradiction.
+
+_Mammalia of New Zealand._--The only undoubtedly indigenous mammalia appear
+to be two species of bats, one of which (_Scotophilus tuberculatus_) is,
+according to Mr. Dobson, identical with an Australian form, while the other
+(_Mystacina tuberculata_) forms a very remarkable and isolated genus of
+Emballonuridæ, a family which extends throughout all the tropical regions
+of the globe. The genus Mystacina was formerly considered to belong to the
+American Phyllostomidæ, but this has been shown to be an error.[117] The
+poverty of New Zealand in bats is very remarkable when compared with our
+own islands where there are at least twelve distinct species, though we
+have a far less favourable climate.
+
+Of the existence of truly indigenous land mammals in New Zealand there is
+at present no positive evidence, but there is some reason to believe that
+one if not two species may be found there. The Maoris say that before
+Europeans came to their country a forest-rat abounded and was largely used
+for food. They believe that their ancestors brought it with them when they
+first came to the country; but it has now become almost, if not quite,
+exterminated by the European brown rat. What this native animal was is
+still somewhat doubtful. Several specimens have been caught at different
+times which have been declared by the natives to be the true _Kiore
+Maori_--as they term it, but these have usually proved on examination to be
+either the European black rat or some of the native Australian rats which
+now {475} often find their way on board ships. But within the last few
+years many skulls of a rat have been obtained from the old Maori
+cooking-places, and from a cave associated with moa bones; and Captain
+Hutton, who has examined them, states that they belong to a true Mus, but
+differ from the _Mus rattus_. This animal might have been on the islands
+when the Maoris first arrived, and in that case would be truly indigenous;
+while the Maori legend of their "ancestors" bringing the rat from their
+Polynesian home may be altogether a myth invented to account for its
+presence in the islands, because the only other land mammal which they
+knew--the dog--was certainly so brought. The question can only be settled
+by the discovery of remains of a rat in some deposit of an age decidedly
+anterior to the first arrival of the Maori race in New Zealand.[118]
+
+Much more interesting is the reported existence in the mountains of the
+South Island of a small otter-like animal. Dr. Haast has seen its tracks,
+resembling those of our European otter, at a height of 3,000 feet above the
+sea in a region never before trodden by man; and the animal itself was seen
+by two gentlemen near Lake Heron, about seventy miles due west of
+Christchurch. It was described as being dark brown and the size of a large
+rabbit. On being struck at with a whip, it uttered a shrill yelping sound
+and disappeared in the water.[119] An animal seen so closely as to be
+struck at with a whip could hardly have been mistaken for a dog--the only
+other animal that it could possibly be supposed to have been, and a dog
+would certainly not have "disappeared in the water." This account, as well
+as the footsteps, point to an aquatic animal; and if it now frequents only
+the high alpine lakes and streams, this might explain why it has never yet
+been captured. Hochstetter also states that it has a native
+name--Waitoteke--a striking evidence of its actual existence, while a
+gentleman who lived many years in the district assures me that {476} it is
+universally believed in by residents in that part of New Zealand. The
+actual capture of this animal and the determination of its characters and
+affinities could not fail to aid us greatly in our speculations as to the
+nature and origin of the New Zealand fauna.[120]
+
+_Wingless Birds, Living and Extinct._--Almost equally valuable with
+mammalia in affording indications of geographical changes are the wingless
+birds for which New Zealand is so remarkable. These consist of four species
+of Apteryx, called by the natives "kiwis,"--creatures which hardly look
+like birds owing to the apparent absence (externally) of tail or wings and
+the dense covering of hair-like feathers. They vary in size from that of a
+small fowl up to that of a turkey, and have a long slightly curved bill,
+somewhat resembling that of the snipe or ibis. Two species appear to be
+confined to the South Island, and one to the North Island, but all are
+becoming scarce, and they will no doubt gradually become extinct. These
+birds are generally classed with the Struthiones or ostrich tribe, but they
+form a distinct family, and in many respects differ greatly from all other
+known birds.
+
+But besides these, a number of other wingless birds, called "moas,"
+inhabited New Zealand during the period of human occupation, and have only
+recently become extinct. These were much larger birds than the kiwis, and
+some of them were even larger than the ostrich, a specimen {477} of
+_Dinornis maximus_ mounted in the British Museum in its natural attitude
+being eleven feet high. They agreed, however, with the living Apteryx in
+the character of the pelvis and some other parts of the skeleton, while in
+their short bill and in some important structural features they resembled
+the emu of Australia and the cassowaries of New Guinea.[121] No less than
+eleven distinct species of these birds have now been discovered; and their
+remains exist in such abundance--in recent fluviatile deposits, in old
+native cooking places, and even scattered on the surface of the
+ground--that complete skeletons of several of them have been put together,
+illustrating various periods of growth from the chick up to the adult bird.
+Feathers have also been found attached to portions of the skin, as well as
+the stones swallowed by the birds to assist digestion, and eggs, some
+containing portions of the embryo bird; so that everything confirms the
+statements of the Maoris--that their ancestors found these birds in
+abundance on the islands, that they hunted them for food, and that they
+finally exterminated them only a short time before the arrival of
+Europeans.[122] Bones of Apteryx are also found fossil, but apparently of
+the same species as the living birds. {478} How far back in geological time
+these creatures or their ancestral types lived in New Zealand we have as
+yet no evidence to show. Some specimens have been found under a
+considerable depth of fluviatile deposits which may be of Quaternary or
+even of Pliocene age; but this evidently affords us no approximation to the
+time required for the origin and development of such highly peculiar
+insular forms.
+
+_Past Changes of New Zealand deduced from its Wingless Birds._--It has been
+well observed by Captain Hutton, in his interesting paper already referred
+to, that the occurrence of such a number of species of Struthious birds
+living together in so small a country as New Zealand is altogether
+unparalleled elsewhere on the globe. This is even more remarkable when we
+consider that the species are not equally divided between the two islands,
+for remains of no less than ten out of the eleven known species of Dinornis
+have been found in a single swamp in the South Island, where also three of
+the species of Apteryx occur. The New Zealand Struthiones, in fact, very
+nearly equal in number those of all the rest of the world, and nowhere else
+do more than three species occur in any one continent or island, while no
+more than two ever occur in the same district. Thus, there appear to be two
+closely allied species of ostriches inhabiting Africa and South-western
+Asia respectively. South America has three species of Rhea, each in a
+separate district. Australia has an eastern and a western variety of emu,
+and a cassowary in the north; while eight other cassowaries are known from
+the islands north of Australia--one from Ceram, two from the Aru Islands,
+one from Jobie, one from New Britain, and three from New Guinea--but of
+these last one is confined to the northern and another to the southern part
+of the island.
+
+This law, of the distribution of allied species in separate areas--which is
+found to apply more or less accurately to all classes of animals--is so
+entirely opposed to the crowding together of no less that fifteen species
+of wingless birds in the small area of New Zealand, that the idea is at
+once suggested of great geographical changes. Captain Hutton points out
+that if the islands from Ceram to New Britain {479} were to become joined
+together, we should have a large number of species of cassowary (perhaps
+several more than are yet discovered) in one land area. If now this land
+were gradually to be submerged, leaving a central elevated region, the
+different species would become crowded together in this portion just as the
+moas and kiwis were in New Zealand. But we also require, at some remote
+epoch, a more or less complete union of the islands now inhabited by the
+separate species of cassowaries, in order that the common ancestral form
+which afterwards became modified into these species, could have reached the
+places where they are now found; and this gives us an idea of the complete
+series of changes through which New Zealand is believed to have passed in
+order to bring about its abnormally dense population of wingless birds.
+First, we must suppose a land connection with some country inhabited by
+struthious birds, from which the ancestral forms might be derived;
+secondly, a separation into many considerable islands, in which the various
+distinct species might become differentiated; thirdly, an elevation
+bringing about the union of these islands to unite the distinct species in
+one area; and fourthly, a subsidence of a large part of the area, leaving
+the present islands with the various species crowded together.
+
+If New Zealand has really gone through such a series of changes as here
+suggested, some proofs of it might perhaps be obtained in the outlying
+islands which were once, presumably, joined with it. And this gives great
+importance to the statement of the aborigines of the Chatham Islands, that
+the Apteryx formerly lived there but was exterminated about 1835. It is to
+be hoped that some search will be made here and also in Norfolk Island, in
+both of which it is not improbable remains either of Apteryx or Dinornis
+might be discovered.
+
+So far we find nothing to object to in the speculations of Captain Hutton,
+with which, on the contrary, we almost wholly concur; but we cannot follow
+him when he goes on to suggest an Antarctic continent uniting New Zealand
+and Australia with South America, and probably also with South Africa, in
+order to explain the existing distribution {480} of struthious birds. Our
+best anatomists, as we have seen, agree that both Dinornis and Apteryx are
+more nearly allied to the cassowaries and emus than to the ostriches and
+rheas; and we see that the form of the sea-bottom suggests a former
+connection with North Australia and New Guinea--the very region where these
+types most abound, and where in all probability they originated. The
+suggestion that all the struthious birds of the world sprang from a common
+ancestor at no very remote period, and that their existing distribution is
+due to direct land communication between the countries they _now_ inhabit,
+is one utterly opposed to all sound principles of reasoning in questions of
+geographical distribution. For it depends upon two assumptions, both of
+which are at least doubtful, if not certainly false--the first, that their
+distribution over the globe has never in past ages been very different from
+what it is now; and the second, that the ancestral forms of these birds
+never had the power of flight. As to the first assumption, we have found in
+almost every case that groups now scattered over two or more continents
+formerly lived in intervening areas of existing land. Thus the marsupials
+of South America and Australia are connected by forms which lived in North
+America and Europe; the camels of Asia and the llamas of the Andes had many
+extinct common ancestors in North America; the lemurs of Africa and Asia
+had their ancestors in Europe, as had the trogons of South America, Africa,
+and tropical Asia. But besides this general evidence we have direct proof
+that the struthious birds had a wider range in past times than now. Remains
+of extinct rheas have been found in Central Brazil, and those of ostriches
+in North India; while remains, believed to be of struthious birds, are
+found in the Eocene deposits of England; and the Cretaceous rocks of North
+America have yielded the extraordinary toothed bird, Hesperornis, which
+Professor O. Marsh declares to have been "a carnivorous swimming ostrich."
+
+As to the second point, we have the remarkable fact that all known birds of
+this group have not only the rudiments of wing-bones, but also the
+rudiments of wings, that is, an external limb bearing rigid quills or
+largely-developed {481} plumes. In the cassowary these wing-feathers are
+reduced to long spines like porcupine-quills, while even in the Apteryx,
+the minute external wing bears a series of nearly twenty stiff quill-like
+feathers.[123] These facts render it almost certain that the struthious
+birds do not owe their imperfect wings to a direct evolution from a
+reptilian type, but to a retrograde development from some low form of
+winged birds, analogous to that which has produced the dodo and the
+solitaire from the more highly-developed pigeon-type. Professor Marsh has
+proved, that so far back as the Cretaceous period, the two great forms of
+birds--those with a keeled sternum and fairly-developed wings, and those
+with a convex keel-less sternum and rudimentary wings--already existed side
+by side; while in the still earlier Archæopteryx of the Jurassic period we
+have a bird with well-developed wings, and therefore probably with a keeled
+sternum. We are evidently, therefore, very far from a knowledge of the
+earliest stages of bird life, and our acquaintance with the various forms
+that have existed is scanty in the extreme; but we may be sure that birds
+acquired wings, and feathers, and some power of flight, before they
+developed a keeled sternum, since we see that bats with no such keel fly
+very well. Since, therefore, the struthious birds all have perfect
+feathers, and all have rudimentary wings, which are anatomically those of
+true birds, not the rudimentary fore-legs of reptiles, and since we know
+that in many higher groups of birds--as the pigeons and the rails--the
+wings have become more or less aborted, and the keel of the sternum greatly
+reduced in size by disuse, it seems probable that the very remote ancestors
+of the rhea, the cassowary, and the apteryx, were true flying birds,
+although not perhaps provided with a keeled sternum, or possessing very
+great powers of flight. But in addition to the possible ancestral power of
+flight, we have the undoubted fact that the rhea and the emu both swim
+freely, the former having been seen swimming from island to island off the
+coast of Patagonia. This, taken in connection with the wonderful aquatic
+ostrich of the Cretaceous period discovered by Professor Marsh, opens {482}
+up fresh possibilities of migration; while the immense antiquity thus given
+to the group and their universal distribution in past time, renders all
+suggestions of special modes of communication between the parts of the
+globe in which their scattered remnants _now_ happen to exist, altogether
+superfluous and misleading.
+
+The bearing of this argument on our present subject is, that so far as
+accounting for the presence of wingless birds in New Zealand is concerned,
+we have nothing whatever to do with any possible connection, by way of a
+southern continent or antarctic islands, with South America and South
+Africa, because the nearest allies of its moas and kiwis are the
+cassowaries and emus, and we have distinct indications of a former land
+extension towards North Australia and New Guinea, which is exactly what we
+require for the original entrance of the struthious type into the New
+Zealand area.
+
+_Winged Birds and Lower Vertebrates of New Zealand._--Having given a pretty
+full account of the New Zealand fauna elsewhere[124] I need only here point
+out its bearing on the hypothesis now advanced, of the former
+land-connection having been with North Australia, New Guinea, and the
+Western Pacific Islands, rather than with the temperate regions of
+Australia.
+
+Of the Australian genera of birds, which are found also in New Zealand,
+almost every one ranges also into New Guinea or the Pacific Islands, while
+the few that do not extend beyond Australia are found in its northern
+districts. As regards the peculiar New Zealand genera, all whose affinities
+can be traced are allied to birds which belong to the tropical parts of the
+Australian region; while the starling family, to which four of the most
+remarkable New Zealand birds belong (the genera Creadion, Heterolocha, and
+Callæas), is totally wanting in temperate Australia and is comparatively
+scarce in the entire Australian region, but is abundant in the Oriental
+region, with which New Guinea and the Moluccas are in easy communication.
+It is certainly a most suggestive fact that there are more than sixty {483}
+genera of birds peculiar to the Australian continent (with Tasmania), many
+of them almost or quite confined to its temperate portions, and that no
+single one of these should be represented in temperate New Zealand.[125]
+The affinities of the living and more highly organised, no less than those
+of the extinct and wingless birds, strikingly accord with the line of
+communication indicated by the deep submarine bank connecting these
+temperate islands with the tropical parts of the Australian region.
+
+The reptiles, so far as they go, are quite in accordance with the birds.
+The lizards belong to two genera, Lygosoma, which has a wide range in all
+the tropics as well as in Australia; and Naultinus, a genus peculiar to New
+Zealand, but belonging to a family--Geckonidæ--spread over the whole of the
+warmer parts of the world. Australia, with New Guinea, on the other hand,
+has a peculiar family, and no less than twenty-one peculiar genera of
+lizards, many of which are confined to its temperate regions, but no one of
+them extends to temperate New Zealand.[126] The extraordinary lizard-like
+_Hatteria punctata_ of New Zealand forms of itself a distinct order of
+reptiles, in some respects intermediate between lizards and crocodiles, and
+having therefore no affinity with any living animal.
+
+The only representative of the Amphibia in New Zealand is a solitary frog
+of a peculiar genus (_Liopelma hochstetteri_); but it has no affinity for
+any of the Australian frogs, which are numerous, and belong to eleven
+different families; while the Liopelma belongs {484} to a very distinct
+family (Discoglossidæ), confined to the Palæarctic region.
+
+Of the fresh-water fishes we need only say here, that none belong to
+peculiar Australian types, but are related to those of temperate South
+America or of Asia.
+
+The Invertebrate classes are comparatively little known, and their modes of
+dispersal are so varied and exceptional that the facts presented by their
+distribution can add little weight to those already adduced. We will,
+therefore, now proceed to the conclusions which can fairly be drawn from
+the general facts of New Zealand natural history already known to us.
+
+_Deductions from the Peculiarities of the New Zealand Fauna._--The total
+absence (or extreme scarcity) of mammals in New Zealand obliges us to place
+its union with North Australia and New Guinea at a very remote epoch. We
+must either go back to a time when Australia itself had not yet received
+the ancestral forms of its present marsupials and monotremes, or we must
+suppose that the portion of Australia with which New Zealand was connected
+was then itself isolated from the mainland, and was thus without a
+mammalian population. We shall see in our next chapter that there are
+certain facts in the distribution of plants, no less than in the geological
+structure of the country, which favour the latter view. But we must on any
+supposition place the union very far back, to account for the total want of
+identity between the winged birds of New Zealand and those peculiar to
+Australia, and a similar want of accordance in the lizards, the fresh-water
+fishes, and the more important insect-groups of the two countries. From
+what we know of the long geological duration of the generic types of these
+groups we must certainly go back to the earlier portion of the Tertiary
+period at least, in order that there should be such a complete disseverance
+as exists between the characteristic animals of the two countries; and we
+must further suppose that, since their separation, there has been no
+subsequent union or sufficiently near approach to allow of any important
+intermigration, even of winged birds, between them. It seems probable,
+therefore, that {485} the Bampton shoal west of New Caledonia, and Lord
+Howe's Island further south, formed the western limits of that extensive
+land in which the great wingless birds and other isolated members of the
+New Zealand fauna were developed. Whether this early land extended eastward
+to the Chatham Islands and southward to the Macquaries we have no means of
+ascertaining, but as the intervening sea appears to be not more than about
+1,500 fathoms deep it is quite possible that such an amount of subsidence
+may have occurred. It is possible, too, that there may have been an
+extension northward to the Kermadec Islands, and even further to the Tonga
+and Fiji Islands, though this is hardly probable, or we should find more
+community between their productions and those of New Zealand.
+
+A southern extension towards the Antarctic continent at a somewhat later
+period seems more probable, as affording an easy passage for the numerous
+species of South American and Antarctic plants, and also for the identical
+and closely allied fresh-water fishes of these countries.
+
+The subsequent breaking up of this extensive land into a number of separate
+islands in which the distinct species of moa and kiwi were developed--their
+union at a later period, and the final submergence of all but the existing
+islands, is a pure hypothesis, which seems necessary to explain the
+occurrence of so many species of these birds in a small area but of which
+we have no independent proof. There are, however, some other facts which
+would be explained by it, as the presence of three peculiar but allied
+genera of starlings, the three species of parrots of the genus Nestor, and
+the six distinct rails of the genus Ocydromus, as well as the numerous
+species in some of the peculiar New Zealand genera of plants, which seem
+less likely to have been developed in a single area than when isolated, and
+thus preserved from the counteracting influence of intercrossing.
+
+In the present state of our knowledge these seem all the conclusions we can
+arrive at from a study of the New Zealand fauna; but as we fortunately
+possess a tolerably {486} full and accurate knowledge of the flora of New
+Zealand, as well as of that of Australia and the south temperate lands
+generally, it will be well to see how far these conclusions are supported
+by the facts of plant distribution, and what further indications they
+afford us of the early history of these most interesting countries. This
+inquiry is of sufficient importance to occupy a separate chapter.
+
+ * * * * *
+
+
+{487}
+
+CHAPTER XXII
+
+THE FLORA OF NEW ZEALAND: ITS AFFINITIES AND PROBABLE ORIGIN
+
+ Relations of the New Zealand Flora to that of Australia--General
+ Features of the Australian Flora--The Floras of South-eastern and
+ South-western Australia--Geological Explanation of the Differences of
+ these two Floras--The Origin of the Australian Element in the New
+ Zealand Flora--Tropical Character of the New Zealand Flora
+ Explained--Species Common to New Zealand and Australia mostly Temperate
+ Forms--Why Easily Dispersed Plants have often Restricted
+ Ranges--Summary and Conclusion on the New Zealand Flora.
+
+Although plants have means of dispersal far exceeding those possessed by
+animals, yet as a matter of fact comparatively few species are carried for
+very great distances, and the flora of a country taken as a whole usually
+affords trustworthy indications of its past history. Plants, too, are more
+numerous in species than the higher animals, and are almost always better
+known; their affinities have been more systematically studied; and it may
+be safely affirmed that no explanation of the origin of the fauna of a
+country can be sound, which does not also explain, or at least harmonise
+with, the distribution and relations of its flora. The distribution of the
+two may be very different, but both should be explicable by the same series
+of geographical changes.
+
+The relations of the flora of New Zealand to that of Australia have long
+formed an insoluble enigma for {488} botanists. Sir Joseph Hooker, in his
+most instructive and masterly essay on the flora of Australia,
+says:--"Under whatever aspect I regard the flora of Australia and of New
+Zealand, I find all attempts to theorise on the possible causes of their
+community of feature frustrated by anomalies in distribution, such as I
+believe no two other similarly situated countries in the globe present.
+Everywhere else I recognise a parallelism or harmony in the main common
+features of contiguous floras, which conveys the impression of their
+generic affinity, at least, being affected by migration from centres of
+dispersion in one of them, or in some adjacent country. In this case it is
+widely different. Regarding the question from the Australian point of view,
+it is impossible in the present state of science to reconcile the fact of
+Acacia, Eucalyptus, Casuarina, Callitris, &c., being absent in New Zealand,
+with any theory of transoceanic migration that may be adopted to explain
+the presence of other Australian plants in New Zealand; and it is very
+difficult to conceive of a time or of conditions that could explain these
+anomalies, except by going back to epochs when the prevalent botanical as
+well as geographical features of each were widely different from what they
+are now. On the other hand, if I regard the question from the New Zealand
+point of view, I find such broad features of resemblance, and so many
+connecting links that afford irresistible evidence of a close botanical
+connection, that I cannot abandon the conviction that these great
+differences will present the least difficulties to whatever theory may
+explain the whole case." I will now state, as briefly as possible, what are
+the facts above referred to as being of so anomalous a character, and there
+is little difficulty in doing so, as we have them fully set forth, with
+admirable clearness, in the essay above alluded to, and in the same
+writer's _Introduction to the Flora of New Zealand_, only requiring some
+slight modifications, owing to the later discoveries which are given in the
+_Handbook of the New Zealand Flora_.
+
+Confining ourselves always to flowering plants, we find that the flora of
+New Zealand is a very poor one, considering the extent of surface, and the
+favourable conditions of {489} soil and climate. It consists of 1,085
+species (our own islands possessing about 1,500), but a very large
+proportion of these are peculiar, there being no less than 800 endemic
+species, and thirty-two endemic genera.
+
+Out of the 285 species not peculiar to New Zealand, no less than 215 are
+Australian, but a considerable number of these are also Antarctic, South
+American, or European; so that there are only about 100 _species_
+absolutely confined to New Zealand and Australia, and, what is important as
+indicating a somewhat recent immigration, only some half-dozen of these
+belong to _genera_ which are peculiar to the two countries, and hardly any
+to the larger and more important Australian genera. Many, too, are rare
+species in both countries and are often alpines.
+
+Far more important are the relations of the genera and families of the two
+countries. All the Natural Orders of New Zealand are found in Australia
+except three--Coriariæ, a widely-scattered group found in South Europe, the
+Himalayas, and the Andes; Escallonieæ, a widely distributed group; and
+Chloranthaceæ, found in Tropical Asia, Japan, Polynesia, and South America.
+Out of a total of 310 New Zealand genera, no less than 248 are Australian,
+and sixty of these are almost peculiar to the two countries, only
+thirty-two however being absolutely confined to them.[127] In the three
+large orders--Compositæ, Orchideæ, and Gramineæ, the genera are almost
+identical in the two countries, while the species--in the two former
+especially--are mostly distinct.
+
+Here then we have apparently a wonderful resemblance between the New
+Zealand flora and that of Australia, indicated by more than two-thirds of
+the non-peculiar species, and more than nine-tenths of the non-peculiar
+genera (255) being Australian. But now let us look at the other side of the
+question.
+
+There are in Australia seven great genera of plants, each containing more
+than 100 species, all widely spread over {490} the country, and all highly
+characteristic Australian forms,--Acacia, Eucalyptus, Melaleuca,
+Leucopogon, Stylidium, Grevillea, and Hakea. These are entirely absent from
+New Zealand, except one species of Leucopogon, a genus which also has
+representatives in the Malayan and Pacific Islands. Sixteen more Australian
+genera have over fifty species each, and of these eight are totally absent
+from New Zealand, five are represented by one or two species, and only two
+are fairly represented; but these two--Drosera and Helichrysum--are very
+widespread genera, and might have reached New Zealand from other countries
+than Australia.
+
+But this by no means exhausts the differences between New Zealand and
+Australia. No less than seven Australian Natural Orders--Dilleniaceæ,
+Buettneriaceæ, Polygaleæ, Tremandreæ, Casuarineæ, Hæmodoraceæ, and Xyrideæ
+are entirely wanting in New Zealand, and several others which are
+excessively abundant and highly characteristic of the former country are
+very poorly represented in the latter. Thus, Leguminosæ are extremely
+abundant in Australia, where there are over 1,000 species belonging to
+about 100 genera, many of them altogether peculiar to the country; yet in
+New Zealand this great order is most scantily represented, there being only
+five genera and thirteen species; and only two of these genera, Swainsonia
+and Clianthus, are Australian, and as the latter consists of but two
+species it may as well have passed from New Zealand to Australia as the
+other way, or more probably from some third country to them both.[128]
+Goodeniaceæ with ten genera and 220 species Australian, has but two species
+in New Zealand--and one of these is a salt-marsh plant found also in
+Tasmania and in Chile; and four other large Australian orders--Rhamneæ,
+Myoporineæ, Proteaceæ and Santalaceæ, have very few representatives in New
+Zealand.
+
+We find, then, that the great fact we have to explain and account for is,
+the undoubted affinity of the New {491} Zealand flora to that of Australia,
+but an affinity almost exclusively confined to the least predominant and
+least peculiar portion of that flora, leaving the most predominant, most
+characteristic, and most widely distributed portion absolutely
+unrepresented. We must however be careful not to exaggerate the amount of
+affinity with Australia, apparently implied by the fact that nearly
+six-sevenths of the New Zealand genera are also Australian, for, as we have
+already stated, a very large number of these are European, Antarctic, South
+American or Polynesian genera, whose presence in the two contiguous areas
+only indicates a common origin. About one-eighth, only, are absolutely
+confined to Australia and New Zealand (thirty-two genera), and even of
+these several are better represented in New Zealand than in Australia, and
+may therefore have passed from the former to the latter. No less than 174
+of the New Zealand genera are temperate South American, many being also
+Antarctic or European; while others again are especially tropical or
+Polynesian; yet undoubtedly a larger proportion of the Natural Orders and
+genera are common to Australia than to any other country, so that we may
+say that the basis of the flora is Australian with a large intermixture of
+northern and southern temperate forms and others which have remote
+world-wide affinities.
+
+_General Features of the Australian Flora and its Probable Origin._--Before
+proceeding to point out how the peculiarities of the New Zealand flora may
+be best accounted for, it is necessary to consider briefly what are the
+main peculiarities of Australian vegetation, from which so important a part
+of that of New Zealand has evidently been derived.
+
+The actual Australian flora consists of two great divisions--a temperate
+and a tropical, the temperate being again divisible into an eastern and a
+western portion. All that is most characteristic of the Australian flora
+belongs to the temperate division (though these often overspread the whole
+continent), in which are found almost all the remarkable Australian types
+of vegetation and the numerous genera peculiar to this part of the world.
+Contrary to what occurs in most other countries, the {492} tropical appears
+to be less rich in species and genera than the temperate region, and what
+is still more remarkable it contains fewer peculiar species, and very few
+peculiar genera. Although the area of tropical Australia is about equal to
+that of the temperate portions, and it has now been pretty well explored
+botanically, it has probably not more than half as many species.[129]
+Nearly 500 of its species are identical with Indian or Malayan plants, or
+are very close representatives of them; while there are more than 200
+Indian genera, confined for the most part to the tropical portion of
+Australia. The remainder of the tropical flora consists of a few species
+and many genera of temperate {493} Australia which range over the whole
+continent, but these form only a small portion of the peculiarly Australian
+genera.
+
+These remarkable facts clearly point to one conclusion--that the flora of
+tropical Australia is, comparatively, recent and derivative. If we imagine
+the greater part of North Australia to have been submerged beneath the
+ocean, from which it rose in the middle or latter part of the Tertiary
+period, offering an extensive area ready to be covered by such suitable
+forms of vegetation as could first reach it, something like the present
+condition of things would inevitably arise. From the north, widespread
+Indian and Malay plants would quickly enter, while from the south the most
+dominant forms of warm-temperate Australia, and such as were best adapted
+to the tropical climate and arid soil, would intermingle with them. Even if
+numerous islands had occupied the area of Northern Australia for long
+periods anterior to the final elevation, very much the same state of things
+would result.
+
+The existence in North and North-east Australia of enormous areas covered
+with Cretaceous and other Secondary deposits, as well as extensive Tertiary
+formations, lends support to the view, that during very long epochs
+temperate Australia was cut off from all close connection with the tropical
+and northern lands by a wide extent of sea; and this isolation is exactly
+what was required, in order to bring about the wonderful amount of
+specialisation and the high development manifested by the typical
+Australian flora. Before proceeding further, however, let us examine this
+flora itself, so far as regards its component parts and probable past
+history.
+
+_The Floras of South-eastern and South-western Australia._--The
+peculiarities presented by the south-eastern and south-western subdivisions
+of the flora of temperate Australia are most interesting and suggestive,
+and are, perhaps, unparalleled in any other part of the world. South-west
+Australia is far less extensive than the south-eastern division--less
+varied in soil and climate, with no lofty mountains, and much sandy desert;
+yet, strange to say, it contains an equally rich flora and a far greater
+proportion of peculiar species and genera of plants. As Sir {494} Joseph
+Hooker remarks:--"What differences there are in conditions would, judging
+from analogy with other countries, favour the idea that South-eastern
+Australia, from its far greater area, many large rivers, extensive tracts
+of mountainous country and humid forests, would present much the most
+extensive flora, of which only the drier types could extend into
+South-western Australia. But such is not the case; for though the far
+greater area is much the best explored, presents more varied conditions,
+and is tenanted by a larger number of Natural Orders and genera, these
+contain fewer species by several hundreds."[130]
+
+The fewer genera of South-western Australia are due almost wholly to the
+absence of the numerous European, Antarctic, and South-American types found
+in the south-eastern region, while in purely Australian types it is far the
+richer, for while it contains most of those found in the east it has a
+large number altogether peculiar to it; and Sir Joseph Hooker states that
+"there are about 180 genera, out of 600 in South-western Australia, that
+are either not found at all in South-eastern, or that are represented there
+by a very few species only, and these 180 genera include nearly 1,100
+species."
+
+_Geological Explanation of the Differences of these Two Floras._--These
+facts again clearly point to the conclusion that South-western Australia is
+the remnant of the more extensive and more isolated portion of the
+continent in which the peculiar Australian flora was principally developed.
+The existence there of a very large area of granite--800 miles in length by
+nearly 500 in maximum width with detached masses 200 miles to the north and
+500 miles to the east--indicates such an extension; for these {495}
+granitic masses were certainly once buried under piles of stratified rock,
+since denuded, and then formed the nucleus of the old Western Australian
+continent. If we take the 1000-fathom line around the southern part of
+Australia to represent the probable extension of this old land we shall see
+that it would give a wide additional area south of the Great Australian
+Bight, and form a continent which, even if the greater part of tropical
+Australia were submerged, would be sufficient for the development of a
+peculiar and abundant flora. We must also remember that an elevation of
+6000 feet, added to the vast amount which has been taken away by
+denudation, would change the whole country, including what are now the
+deserts of the interior, into a mountainous and well-watered region.
+
+But while this rich and peculiar flora was in process of formation, the
+eastern portion of the continent must either have been widely separated
+from the western or had perhaps not yet risen from the ocean. The whole of
+this part of the country consists of Palæozoic and Secondary formations
+with granite and metamorphic rocks, the Secondary deposits being largely
+developed on both sides of the central range, extending the whole length of
+the continent from Tasmania to Cape York, and constituting the greater part
+of the plateau of the Blue Mountains and other lofty ranges. During some
+portion of the Secondary and Tertiary periods therefore, this side of
+Australia must have been almost wholly submerged beneath the ocean; and if
+we suppose that during this time the western part of the continent was at
+nearly its maximum extent and elevation, we shall have a sufficient
+explanation of the great difference between the flora of Western and
+Eastern Australia, since the latter would only have been able to receive
+immigrants from the former, at a later period, and in a more or less
+fragmentary manner.
+
+If we examine the geological map of Australia (given in Stanford's
+Compendium of Geography and Travel, volume _Australasia_), we shall see
+good reason to conclude that the eastern and the western divisions of the
+country first existed as separate islands, and only became united at a
+comparatively recent epoch. This is indicated by an {496} enormous stretch
+of Cretaceous and Tertiary formations extending from the Gulf of
+Carpentaria completely across the continent to the mouth of the Murray
+River. During the Cretaceous period, therefore, and probably throughout a
+considerable portion of the Tertiary epoch,[131] there must have been a
+wide arm of the sea occupying this area, dividing the great mass of land on
+the west--the true seat and origin of the typical Australian flora--from a
+long but narrow belt of land on the east, indicated by the continuous mass
+of Secondary and Palæozoic formations already referred to which extend
+uninterruptedly from Tasmania to Cape York. Whether this formed one
+continuous land, or was broken up into islands, cannot be positively
+determined; but the fact that no marine Tertiary beds occur in the whole of
+this area, renders it probable that it was almost, if not quite,
+continuous, and that it not improbably extended across to what is now New
+Guinea. At this epoch, then (as shown in the accompanying map), Australia
+may, not improbably, have consisted of a very large and fertile western
+island, almost or quite extratropical, and extending from the Silurian
+rocks of the Flinders range in South Australia, to about 150 miles west of
+the present west coast, and southward to about 350 miles south of the Great
+Australian Bight. To the east of this, at a distance of from 250 to 400
+miles, extended in a north and south direction a long but comparatively
+narrow island, stretching from far south of Tasmania to New Guinea; while
+the crystalline and Secondary formations of central North Australia
+probably indicate the existence of one or more large islands in that
+direction.
+
+{497}
+
+ The white portions represent land; the shaded parts sea.
+ The existing land of Australia is shown in outline.]
+
+The eastern and the western islands--with which we are now chiefly
+concerned--would then differ considerably in their vegetation and animal
+life. The western and more ancient land already possessed, in its main
+features, the peculiar Australian flora, and also the ancestral forms of
+its strange marsupial fauna, both of which it had probably received at some
+earlier epoch by a temporary union with the Asiatic continent over what is
+now the Java sea. Eastern Australia, on the other hand, possessed only the
+rudiments of its existing mixed flora, derived from three distinct sources.
+Some important fragments of the typical Australian vegetation had reached
+it across the marine {498} strait, and had spread widely owing to the soil,
+climate and general conditions being exactly suited to it: from the north
+and north-east a tropical vegetation of Polynesian type had occupied
+suitable areas in the north; while the extension southward of the Tasmanian
+peninsula, accompanied, probably, as now, with lofty mountains, favoured
+the immigration of south-temperate forms from whatever Antarctic lands or
+islands then existed. This supposition is strikingly in harmony with what
+is known of the ancient flora of this portion of Australia. In deposits
+supposed to be of Eocene age in New South Wales and Victoria fossil plants
+have been found showing a very different vegetation from that now existing.
+Along with a few Australian types--such as Pittosporum, Knightia, and
+Eucalyptus, there occur birches, alders, oaks, and beeches; while in
+Tasmania in freshwater limestone, apparently of Miocene age, are found
+willows, alders, birches, oaks, and beeches,[132] all except the latter
+genus (Fagus) now quite extinct in Australia.[133] These temperate forms
+probably indicate a more oceanic climate, cooler and moister than at
+present. The union with Western Australia and the establishment of an arid
+interior by modifying the climate may have led to the extinction of many of
+these forms and their replacement by special Australian types more suited
+to the new conditions.
+
+At this time the marsupial fauna had not yet reached this eastern land,
+which was, however, occupied in the north by some ancestral struthious
+birds, which had entered it by way of New Guinea through some very ancient
+continental extension, and of which the emu, the cassowaries, the extinct
+Dromornis of Queensland, and the moas and kiwis of New Zealand, are the
+modified descendants.
+
+_The Origin of the Australian Element in the New Zealand Flora._--We have
+now brought down the history of Australia, as deduced from its geological
+structure and the main features of its existing and Tertiary flora, to the
+period {499} when New Zealand was first brought into close connection with
+it, by means of a great north-western extension of that country, which, as
+already explained in our last chapter, is so clearly indicated by the form
+of the sea bottom (See Map, p. 471). The condition of New Zealand previous
+to this event is very obscure. That it had long existed as a more or less
+extensive land is indicated by its ancient sedimentary rocks; while the
+very small areas occupied by Jurassic and Cretaceous deposits, imply that
+much of the present land was then also above the sea-level. The country had
+probably at that time a scanty vegetation of mixed Antarctic and Polynesian
+origin; but now, for the first time, it would be open to the free
+immigration of such Australian types as were suitable to its climate, and
+which _had already reached the tropical and sub-tropical portions of the
+Eastern Australian island_. It is here that we obtain the clue to those
+strange anomalies and contradictions presented by the New Zealand flora in
+its relation to Australia, which have been so clearly set forth by Sir
+Joseph Hooker, and which have so puzzled botanists to account for. But
+these apparent anomalies cease to present any difficulty when we see that
+the Australian plants in New Zealand were acquired, not directly, but, as
+it were, at second hand, by union with an island which itself had as yet
+only received a portion of its existing flora. And then, further
+difficulties were placed in the way of New Zealand receiving such an
+adequate representation of that portion of the flora which had reached East
+Australia as its climate and position entitled it to, by the fact of the
+union being, not with the temperate, but with the tropical and sub-tropical
+portions of that island, so that only those groups could be acquired which
+were less exclusively temperate, and had already established themselves in
+the warmer portion of their new home.[134]
+
+{500}
+
+It is therefore no matter of surprise, but exactly what we should expect,
+that the great mass of pre-eminently temperate Australian genera should be
+absent from New Zealand, including the whole of such important families as,
+Dilleniaceæ, Tremandreæ, Buettneriacæ, Polygaleæ, Casuarineæ and
+Hæmodoraceæ; while others, such as Rutaceæ, Stackhousieæ, Rhamneæ,
+Myrtaceæ, Proteaceæ, and Santalaceæ, are represented by only a few species.
+Thus, too, we can explain the absence of _all_ the peculiar Australian
+Leguminosæ; for these were still mainly confined to the great western
+island, along with the peculiar Acacias and Eucalypti, which at a later
+period spread over the whole continent. It is equally accordant with the
+view we are maintaining, that among the groups which Sir Joseph Hooker
+enumerates as "keeping up the features of extra tropical Australia in its
+tropical quarter," several should have reached New Zealand, such as
+Drosera, some Pittosporeæ and Myoporineæ, with a few Proteaceæ, Loganiaceæ,
+and Restiaceæ; for most of these are not only found in tropical Australia,
+but also in the Malayan and Pacific islands.
+
+_Tropical Character of the New Zealand Flora Explained._--In this origin of
+the New Zealand fauna by a north-western route from North-eastern
+Australia, we find also an explanation of the remarkable number of tropical
+groups of plants found there: for though, as Sir Joseph Hooker has {501}
+shown, a moist and uniform climate favours the extension of tropical forms
+in the temperate zone, yet some means must be afforded them for reaching a
+temperate island. On carefully going through the _Handbook_, and comparing
+its indications with those of Bentham's _Flora Australiensis_, I find that
+there are in New Zealand thirty-eight thoroughly tropical genera,
+thirty-three of which are found in Australia--mostly in the tropical
+portion of it, though a few are temperate, and these may have reached it
+through New Zealand[135]. To these we must add thirty-two more genera,
+which, though chiefly developed in temperate Australia, extend into the
+tropical or sub-tropical portions of it, and may well have reached New
+Zealand by the same route.
+
+On the other hand we find but few New Zealand genera certainly derived from
+Australia which are especially temperate, and it may be as well to give a
+list of such as {502} do occur with a few remarks. They are sixteen in
+number, as follows:--
+
+ 1. Pennantia (1 sp.). This genus has a species in Norfolk Island,
+ indicating perhaps its former extension to the north-west.
+
+ 2. Pomaderris (3 sp.). One _species_ inhabits Victoria and New Zealand,
+ indicating recent trans-oceanic migration.
+
+ 3. Quintinia (2 sp.). This genus has winged seeds facilitating
+ migration.
+
+ 4. Olearia (20 sp.). Seeds with pappus.
+
+ 5. Craspedia (2 sp.). Seeds with pappus. Alpine; identical with
+ Australian species, and therefore of comparatively recent introduction.
+
+ 6. Celmisia (25 sp.). Seeds with pappus. Only three Australian species,
+ two of which are identical with New Zealand forms, probably therefore
+ derived from New Zealand.
+
+ 7. Ozothamnus (5 sp.). Seeds with pappus.
+
+ 8. Epacris (4 sp.). Minute seeds. Some species are sub-tropical, and
+ they are all found in the northern (warmer) island of New Zealand.
+
+ 9. Archeria (2 sp.). Minute seeds. A species common to E. Australia and
+ New Zealand.
+
+ 10. Logania (3 sp.). Small seeds. Alpine plants.
+
+ 11. Hedycarya (1 sp.).
+
+ 12. Chiloglottis (1 sp.). Minute seeds. In Auckland Islands; alpine in
+ Australia.
+
+ 13. Prasophyllum (1 sp.). Minute seeds. Identical with Australian
+ species, indicating recent transmission.
+
+ 14. Orthoceras (1 sp.). Minute seeds. Identical with an Australian
+ species.
+
+ 15. Alepyrum (1 sp.). Alpine, moss-like. An Antarctic type.
+
+ 16. Dichelachne (3 sp.). Identical with Australian species. An awned
+ grass.
+
+We thus see that there are special features in most of these plants that
+would facilitate transmission across the sea between temperate Australia
+and New Zealand, or to both from some Antarctic island; and the fact that
+in several of them the species are absolutely identical shows that such
+transmission has occurred in geologically recent times.
+
+_Species Common to New Zealand and Australia Mostly Temperate Forms._--Let
+us now take the _species_ which are common to New Zealand and Australia,
+but found nowhere else, and which must therefore have passed from one
+country to the other at a more recent period than the mass of _genera_ with
+which we have hitherto been dealing. These are ninety-six in number, and
+they present a striking contrast to the similarly restricted _genera_ in
+being wholly temperate in character, the entire list presenting only a
+{503} single species which is confined to sub-tropical East Australia--a
+grass (_Apera arundinacea_) only found in a few localities on the New
+Zealand coast.
+
+Now it is clear that the larger portion, if not the whole, of these plants
+must have reached New Zealand from Australia (or in a few cases Australia
+from New Zealand), by transmission across the sea, because we know there
+has been no actual land connection during the Tertiary period, as proved by
+the absence of all the Australian mammalia, and almost all the most
+characteristic Australian birds, insects, and plants. The form of the
+sea-bed shows that the distance could not have been less than 600 miles,
+even during the greatest extension of Southern New Zealand and Tasmania;
+and we have no reason to suppose it to have been less, because in other
+cases an equally abundant flora of identical species has reached islands at
+a still greater distance--notably in the case of the Azores and Bermuda.
+The character of the plants is also just what we should expect: for about
+two-thirds of them belong to genera of world-wide range in the temperate
+zones, such as Ranunculus, Drosera, Epilobium, Gnaphalium, Senecio,
+Convolvulus, Atriplex, Luzula, and many sedges and grasses, whose
+exceptionally wide distribution shows that they possess exceptional powers
+of dispersal and vigour of constitution, enabling them not only to reach
+distant countries, but also to establish themselves there. Another set of
+plants belong to especially Antarctic or south temperate groups, such as
+Colobanthus, Acæna, Gaultheria, Pernettya, and Muhlenbeckia, and these may
+in some cases have reached both Australia and New Zealand from some now
+submerged Antarctic island. Again, about one-fourth of the whole are alpine
+plants, and these possess two advantages as colonisers. Their lofty
+stations place them in the best position to have their seeds carried away
+by winds; and they would in this case reach a country which, having derived
+the earlier portion of its flora from the side of the tropics, would be
+likely to have its higher mountains and favourable alpine stations to a
+great extent unoccupied, or occupied by plants unable to compete with
+specially adapted alpine groups. {504}
+
+Fully one-third of the exclusively Australo-New Zealand species belong to
+the two great orders of the sedges and the grasses; and there can be no
+doubt that these have great facilities for dispersion in a variety of ways.
+Their seeds, often enveloped in chaffy glumes, would be carried long
+distances by storms of wind, and even if finally dropped into the sea would
+have so much less distance to reach the land by means of surface currents;
+and Mr. Darwin's experiments show that even cultivated oats germinated
+after 100 days' immersion in sea-water. Others have hispid awns by which
+they would become attached to the feathers of birds, and there is no doubt
+this is an effective mode of dispersal. But a still more important point
+is, probably, that these plants are generally, if not always,
+wind-fertilised, and are thus independent of any peculiar insects, which
+might be wanting in the new country.
+
+_Why Easily-Dispersed Plants have often Restricted Ranges._--This last
+consideration throws light on a very curious point, which has been noted as
+a difficulty by Sir Joseph Hooker, that plants which have most clear and
+decided powers of dispersal by wind or other means, have _not_ generally
+the widest specific range; and he instances the small number of Compositæ
+common to New Zealand and Australia. But in all these cases it will, I
+think, be found that although the _species_ have not a wide range the
+_genera_ often have. In New Zealand, for instance, the Compositæ are very
+abundant, there being no less than 167 species, almost all belonging to
+Australian genera, yet only about one-sixteenth of the whole are identical
+in the two countries. The explanation of this is not difficult. Owing to
+their great powers of dispersal, the Australian Compositæ reached New
+Zealand at a very remote epoch, and such as were adapted to the climate and
+the means of fertilisation established themselves; but being highly
+organised plants with great flexibility of organisation, they soon became
+modified in accordance with the new conditions, producing many special
+forms in different localities; and these, spreading widely, soon took
+possession of all suitable stations. Henceforth immigrants from Australia
+had to compete {505} with these indigenous and well-established plants, and
+only in a few cases were able to obtain a footing; whence it arises that we
+have many Australian types, but few Australian species, in New Zealand, and
+both phenomena are directly traceable to the combination of great powers of
+dispersal with a high degree of adaptability. Exactly the same thing occurs
+with the still more highly specialised Orchideæ. These are not
+proportionally so numerous in New Zealand (thirty-eight species), and this
+is no doubt due to the fact that so many of them require
+insect-fertilisation often by a particular family or genus (whereas almost
+any insect will fertilise Compositæ), and insects of all orders are
+remarkably scarce in New Zealand.[136] This would at once prevent the
+establishment of many of the orchids which may have reached the islands,
+while those which did find suitable fertilisers and other favourable
+conditions would soon become modified into new species. It is thus quite
+intelligible why only three species of orchids are identical in Australia
+and New Zealand, although their minute and abundant seeds must be dispersed
+by the wind almost as readily as the spores of ferns.
+
+Another specialised group--the Scrophularineæ--abounds in New Zealand,
+where there are sixty-two species; but though almost all the genera are
+Australian only three species are so. Here, too, the seeds are usually very
+small, and the powers of dispersal great, as shown by several European
+genera--Veronica, Euphrasia, and Limosella, being found in the southern
+hemisphere.
+
+Looking at the whole series of these Australo-New Zealand plants, we find
+the most highly specialised groups--Compositæ, Scrophularineæ,
+Orchideæ--with a small proportion of identical species (one-thirteenth to
+one twentieth), the less highly specialised--Ranunculaceæ, Onagrariæ and
+Ericeæ--with a higher proportion (one-ninth to one-sixth), and the least
+specialised--Junceæ, {506} Cyperaceæ and Gramineæ--with the high proportion
+in each case of one-fourth. These nine are the most important New Zealand
+orders which contain species common to that country and Australia and
+confined to them; and the marked correspondence they show between high
+specialisation and want of _specific_ identity, while the _generic_
+identity is in all cases approximately equal, points to the conclusion that
+the means of diffusion are, in almost all plants ample, when long periods
+of time are concerned, and that diversities in this respect are not so
+important in determining the peculiar character of a derived flora, as
+adaptability to varied conditions, great powers of multiplication, and
+inherent vigour of constitution. This point will have to be more fully
+discussed in treating of the origin of the Antarctic and north temperate
+members of the New Zealand flora.
+
+_Summary and Conclusion on the New Zealand Flora._--Confining ourselves
+strictly to the direct relations between the plants of New Zealand and of
+Australia, as I have done in the preceding discussion, I think I may claim
+to have shown that the union between the two countries in the latter part
+of the Secondary epoch at a time when Eastern Australia was widely
+separated from Western Australia (as shown by its geological formation and
+by the contour of the sea-bottom) does sufficiently account for all the
+main features of the New Zealand flora. It shows why the basis of the flora
+is fundamentally Australian both as regards orders and genera, for it was
+due either to a direct land connection or a somewhat close approximation
+between the two countries. It shows also why the great mass of typical
+Australian forms are unrepresented, for the Australian flora is typically
+_western_ and _temperate_, and New Zealand received its immigrants from the
+_eastern_ island which had itself received only a fragment of this flora,
+and from the _tropical_ end of this island, and thus could only receive
+such forms as were not exclusively temperate in character. It shows,
+further, why New Zealand contains such a very large proportion of tropical
+forms, for we see that it derived the main portion of its flora directly
+from the tropics. Again, this hypothesis shows us why, though {507} the
+specially Australian _genera_ in New Zealand are largely tropical or
+sub-tropical, the specially Australian _species_ are wholly temperate or
+alpine; for these are comparatively recent arrivals, they must have
+migrated across the sea in the temperate zone, and these temperate and
+alpine forms are exactly such as would be best able to establish themselves
+in a country already stocked mainly by tropical forms and their modified
+descendants. This hypothesis further fulfils the conditions implied in Sir
+Joseph Hooker's anticipation that--"these great differences (of the floras)
+will present the least difficulties to whatever theory may explain the
+whole case,"--for it shows that these differences are directly due to the
+history and development of the Australian flora itself, while the
+resemblances depend upon the most certain cause of all such broad
+resemblances--close proximity or actual land connection.
+
+One objection will undoubtedly be made to the above theory,--that it does
+not explain why some species of the prominent Australian genera Acacia,
+Eucalyptus, Melaleuca, Grevillea, &c., have not reached New Zealand in
+recent times along with the other temperate forms that have established
+themselves. But it is doubtful whether any detailed explanation of such a
+negative fact is possible, while general explanations sufficient to cover
+it are not wanting. Nothing is more certain than that numerous plants never
+run wild and establish themselves in countries where they nevertheless grow
+freely if cultivated; and the explanation of this fact given by Mr.
+Darwin--that they are prevented doing so by the competition of better
+adapted forms--is held to be sufficient. In this particular case, however,
+we have some very remarkable evidence of the fact of their non-adaptation.
+The intercourse between New Zealand and Europe has been the means of
+introducing a host of common European plants,--more than 150 in number, as
+enumerated at the end of the second volume of the _Handbook_; yet, although
+the intercourse with Australia has probably been greater, only two or three
+Australian plants have similarly established themselves. More remarkable
+still, Sir Joseph Hooker states: {508} "I am informed that the late Mr.
+Bidwell habitually scattered Australian seeds during his extensive travels
+in New Zealand." We may be pretty sure that seeds of such excessively
+common and characteristic groups as _Acacia_ and _Eucalyptus_ would be
+among those so scattered, yet we have no record of any plants of these or
+other peculiar Australian genera ever having been found wild, still less of
+their having spread and taken possession of the soil in the way that many
+European plants have done. We are, then, entitled to conclude that the
+plants above referred to have not established themselves in New Zealand
+(although their seeds may have reached it) because they could not
+successfully compete with the indigenous flora which was already well
+established and better adapted to the conditions of climate and of the
+organic environment. This explanation is so perfectly in accordance with a
+large body of well-known facts, including that which is known to every
+one--how few of our oldest and hardiest garden plants ever run wild--that
+the objection above stated will, I feel convinced, have no real weight with
+any naturalists who have paid attention to this class of questions.
+
+ * * * * *
+
+
+{509}
+
+CHAPTER XXIII
+
+ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS
+
+ European Species and Genera of Plants in the Southern
+ Hemisphere--Aggressive Power of the Scandinavian Flora--Means by which
+ Plants have Migrated from North to South--Newly moved Soil as Affording
+ Temporary Stations to Migrating Plants--Elevation and Depression of the
+ Snow-line as Aiding the Migration of Plants--Changes of Climate
+ Favourable to Migration--The Migration from North to South has been
+ long going on--Geological Changes as Aiding Migration--Proofs of
+ Migration by way of the Andes--Proofs of Migration by way of the
+ Himalayas and Southern Asia--Proofs of Migration by way of the African
+ Highlands--Supposed Connection of South Africa and Australia--The
+ Endemic Genera of Plants in New Zealand--The Absence of Southern Types
+ from the Northern Hemisphere--Concluding Remarks on the New Zealand and
+ South Temperate Floras.
+
+We have now to deal with another portion of the New Zealand flora which
+presents perhaps equal difficulties--that which appears to have been
+derived from remote parts of the north and south temperate zones; and this
+will lead us to inquire into the origin of the northern or Arctic element
+in all the south temperate floras.
+
+More than one-third of the entire number of New Zealand genera (115) are
+found also in Europe, and even fifty-eight species are identical in these
+remote parts of the world. Temperate South America has seventy-four genera
+in common with New Zealand, and there are even eleven species identical in
+the two countries, as well as thirty-two which are close allies or
+representative species. {510} A considerable number of these northern or
+Antarctic plants and many more which are representative species, are found
+also in Tasmania and in the mountains of temperate Australia; and Sir
+Joseph Hooker gives a list of thirty-eight species very characteristic of
+Europe and Northern Asia, but almost or quite unknown in the warmer
+regions, which yet reappear in temperate Australia. Other genera seem
+altogether Antarctic--that is, confined to the extreme southern lands and
+islands; and these often have representative species in Southern America,
+Tasmania, and New Zealand, while others occur only in one or two of these
+areas. Many north temperate genera also occur in the mountains of South
+Africa. On the other hand, few if any of the peculiar Australian or
+Antarctic types have spread northwards, except some of the former which
+have reached the mountains of Borneo, and a few of the latter which spread
+along the Andes to Mexico.
+
+On these remarkable facts, of which I have given but the barest outline,
+Sir Joseph Hooker makes the following suggestive observations:--
+
+"When I take a comprehensive view of the vegetation of the Old World, I am
+struck with the appearance it presents of there being a continuous current
+of vegetation (if I may so fancifully express myself) from Scandinavia to
+Tasmania; along, in short, the whole extent of that arc of the terrestrial
+sphere which presents the greatest continuity of land. In the first place
+Scandinavian genera, and even species, reappear everywhere from Lapland and
+Iceland to the tops of the Tasmanian Alps, in rapidly diminishing numbers
+it is true, but in vigorous development throughout. They abound on the Alps
+and Pyrenees, pass on to the Caucasus and Himalayas, thence they extend
+along the Khasia Mountains, and those of the peninsulas of India to those
+of Ceylon and the Malayan Archipelago (Java and Borneo), and after a hiatus
+of 30° they appear on the Alps of New South Wales, Victoria, and Tasmania,
+and beyond these again on those of New Zealand and the Antarctic Islands,
+many of the species remaining unchanged throughout! It matters not what the
+vegetation of the bases and flanks of these mountains may be; the northern
+species may be {511} associated with alpine forms of Germanic, Siberian,
+Oriental, Chinese, American, Malayan, and finally Australian, and Antarctic
+types; but whereas these are all, more or less, local assemblages, the
+Scandinavian asserts his prerogative of ubiquity from Britain to beyond its
+antipodes."[137]
+
+It is impossible to place the main facts more forcibly before the reader
+than in the above striking passage. It shows clearly that this portion of
+the New Zealand flora is due to wide-spread causes which have acted with
+even greater effect in other south temperate lands, and that in order to
+explain its origin we must grapple with the entire problem of the transfer
+of the north temperate flora to the southern hemisphere. Taking, therefore,
+the facts as given by Sir Joseph Hooker in the works already referred to, I
+shall discuss the whole question broadly, and shall endeavour to point out
+the general laws and subordinate causes that, in my opinion, have been at
+work in bringing about the anomalous phenomena of distribution he has done
+so much to make known and to elucidate.
+
+_Aggressive Power of the Scandinavian Flora._--The first important fact
+bearing upon this question is the wonderful aggressive and colonising power
+of the Scandinavian flora, as shown by the way in which it establishes
+itself in any temperate country to which it may gain access. About 150
+species have thus established themselves in New Zealand, often taking
+possession of large tracts of country; about the same number are found in
+Australia, and nearly as many in the Atlantic states of America, where they
+form the commonest weeds. Whether or not we accept Mr. Darwin's explanation
+of this power as due to development in the most extensive land area of the
+globe where competition has been most severe and long-continued, the fact
+of the existence of this power remains, and we can see how important an
+agent it must be in the formation of the floras of any lands to which these
+aggressive plants have been able to gain access.
+
+But not only are these plants pre-eminently capable of holding their own in
+any temperate country in the world, but they also have exceptional powers
+of migration and {512} dispersal over seas and oceans. This is especially
+well shown by the case of the Azores, where no less than 400 out of a total
+of 478 flowering plants are identical with European species. These islands
+are more than 800 miles from Europe, and, as we have already seen in
+Chapter XII., there is no reason for supposing that they have ever been
+more nearly connected with it than they are now, since an extension of the
+European coast to the 1,000-fathom line would very little reduce the
+distance. Now it is a most interesting and suggestive fact that more than
+half the European genera which occur in the Australian flora occur also in
+the Azores, and in several cases even the species are identical in
+both.[138] The importance of such a case as this cannot be exaggerated,
+because it affords a demonstration of the power of the very plants in
+question to pass over wide areas of sea, some no doubt wholly through the
+air, carried by storms in the same way as the European birds and insects
+which annually reach the Azores, others by floating on the waters, or by a
+combination of the two methods; while some may have been carried by aquatic
+birds, to whose feathers many seeds have the power of attaching themselves,
+and some even in the stomachs of fruit or seed eating birds. We have in
+such facts as these a complete disproof of the necessity for those great
+changes of sea and land which are continually appealed to by those who
+think land-connection the only efficient means of accounting for the
+migration of animals or plants; but at the same time we do not neglect to
+make the fullest use of such moderate changes as all the evidence at our
+command leads us to believe have actually occurred, and especially of the
+former existence of intermediate islands, so often indicated by shoals in
+the midst of the deepest oceans.
+
+_Means by which Plants have migrated from North to South._--But if plants
+can thus pass in considerable numbers and variety over wide seas and
+oceans, it must be yet more easy for them to traverse continuous areas of
+land, whereever mountain-chains offer suitable stations at moderate {513}
+intervals on which they might temporarily establish themselves. The
+facilities afforded for the transmission of plants by mountains has hardly
+received sufficient attention. The numerous land-slips, the fresh surfaces
+of broken rock and precipice, the _debris_ of torrents, and the moraines
+deposited by glaciers, afford numerous unoccupied stations on which
+wind-borne seeds have a good chance of germinating. It is a well-known fact
+that fresh surfaces of soil or rock, such as are presented by railway
+cuttings and embankments, often produce plants strange to the locality,
+which survive for a few years, and then disappear as the normal vegetation
+gains strength and permanence.[139] But such a surface {514} will, in the
+meantime, have acted as a fresh centre of dispersal; and thus a plant might
+pass on step by step, by means of stations temporarily occupied, till it
+reached a district {515} where, the general conditions being more
+favourable, it was able to establish itself as a permanent member of the
+flora. Such, generally speaking, was probably the process by which the
+Scandinavian flora has made its way to the southern hemisphere; but it
+could hardly have done so to any important extent without the aid of those
+powerful causes explained in our eighth chapter--causes which acted as a
+constantly recurrent motive-power to produce that "continuous current of
+vegetation" from north to south across the whole width of the tropics
+referred to by Sir Joseph Hooker. Those causes were, the repeated changes
+{516} of climate which, during all geological time, appear to have occurred
+in both hemispheres, culminating at rare intervals in glacial epochs, and
+which have been shown to depend upon changes of excentricity of the earth's
+orbit and the occurrence of summer or winter in _aphelion_, in conjunction
+with the slower and more irregular changes of geographical conditions;
+these combined causes acting chiefly through the agency of heat-bearing
+oceanic currents, and of snow- and ice-collecting highlands. Let us now
+briefly consider how such changes would act in favouring the dispersal of
+plants.
+
+_Elevation and Depression of the Snow Line as Aiding the Migration of
+Plants._--We have endeavoured to show (in an earlier portion of this
+volume) that wherever geographical or physical conditions were such as to
+produce any considerable amount of perpetual snow, this would be increased
+whenever a high degree of excentricity concurred with winter in _aphelion_,
+and diminished during the opposite phase. On all mountain ranges,
+therefore, which reached above the snow-line, there would be a periodical
+increase and decrease of snow, and when there were extensive areas of
+plateau at about the same level, the lowering of the snow-line might cause
+such an increased accumulation of snow as to produce great glaciers and
+ice-fields, such as we have seen occurred in South Africa during the last
+period of high excentricity. But along with such depression of the line of
+perpetual snow there would be a corresponding depression of the alpine and
+sub-alpine zones suitable for the growth of an arctic and temperate
+vegetation, and, what is perhaps more important, the depression would
+necessarily produce a great _extension_ of the area of these zones on all
+high mountains, because as we descend the average slopes become less
+abrupt,--thus affording a number of new stations suitable for such
+temperate plants as might first reach them. But just above and below the
+snow-line is the area of most powerful disintegration and denudation, from
+the alternate action of frost and sun, of ice and water; and thus the more
+extended area would be subject to the constant occurrence of land-slips,
+berg-falls, and floods, with their {517} accompanying accumulations of
+_débris_ and of alluvial soil, affording innumerable stations in which
+solitary wind-borne seeds might germinate and temporarily establish
+themselves.
+
+This lowering and rising of the snow-line each 10,500 years during periods
+of high excentricity, would occur in the northern and southern hemispheres
+alternately; and where there were high mountains within the tropics the two
+would probably overlap each other, so that the northern depression would
+make itself felt in a slight degree even across the equator some way into
+the southern hemisphere, and _vice versâ_; and even if the difference of
+the height of perpetual snow at the two extremes did not average more than
+a few hundred feet, this would be amply sufficient to supply the new and
+unoccupied stations needful to facilitate the migration of plants. It is
+well known that all great mountain ranges have undergone such fluctuations,
+as proved by ice-marks below the present level of snow and ice.
+
+But the differences of temperature in the two hemispheres caused by the sun
+being in _perihelion_ in the winter of the one while it was in _aphelion_
+during the same season in the other, would necessarily lead to increased
+aërial and marine currents, as already explained; and whenever geographical
+conditions were such as to favour the production of glaciation in any area
+these effects would become more powerful, and would further aid in the
+dispersal of the seeds of plants.
+
+_Changes of Climate Favourable to Migration._--It is clear then, that
+during periods when no glacial epochs were produced in the northern
+hemisphere, and even when a mild climate extended over the whole polar
+area, alternate changes of climate favouring the dispersal of plants would
+occur on all high mountains, and with particular force on such as rise
+above the snow-line. But during that long-continued, though comparatively
+recent, phase of high excentricity which produced an extensive glaciation
+in the northern hemisphere and local glaciations in the southern, these
+risings and lowerings of the snow-line on all mountain ranges would have
+been at a maximum, and {518} would have been increased by the depression of
+the ocean which must have arisen from such a vast bulk of water being
+locked up in land-ice, and which depression would have produced the same
+effect as a general elevation of all the continents. At this time, too,
+aërial currents would have attained their maximum of force in both
+hemispheres; and this would greatly facilitate the dispersal of all
+wind-borne seeds as well as of those carried in the plumage or in the
+stomachs of birds, since we have seen, by the cases of the Azores and
+Bermuda, how vastly the migratory powers of birds are increased by a stormy
+atmosphere.
+
+_Migration from North to South has been long going on._--Now, if each phase
+of colder and warmer mountain-climate--each alternate depression and
+elevation of the snow-line, only helped on the migration of a few species
+some stages of the long route from the north to the south temperate
+regions, yet, during the long course of the Tertiary period there might
+well have arisen that representation of the northern flora in the southern
+hemisphere which is now so conspicuous. For it is very important to remark
+that it is not the existing flora alone that is represented, such as might
+have been conveyed during the last glacial epoch only; but we find a whole
+series of northern types evidently of varying degrees of antiquity, while
+even some genera characteristic of the southern hemisphere appear to have
+been originally derived from Europe. Thus Eucalyptus and Metrosideros have
+been determined by Dr. Ettingshausen from their fruits in the Eocene beds
+of Sheppey, while Pimelea, Leptomeria and four genera of Proteaceæ have
+been recognised by Professor Heer in the Miocene of Switzerland; and the
+former writer has detected fifty-five Australian forms in the Eocene plant
+beds of Häring (? Belgium).[140] Then we have such peculiar genera {519} as
+Pachychladon and Notothlaspi of New Zealand said to have affinities with
+Arctic plants, while Stilbocarpa--another peculiar New Zealand genus--has
+its nearest allies in the Himalayan and Chinese Aralias. Following these
+are a whole host of very distinct species of northern genera which may date
+back to any part of the Tertiary period, and which occur in every south
+temperate land. Then we have closely allied representative species of
+European or Arctic plants; and, lastly, a number of identical species,--and
+these two classes are probably due entirely to the action of the last great
+glacial epoch, whose long continuance, and the repeated fluctuations of
+climate with which it commenced and terminated, rendered it an agent of
+sufficient power to have brought about this result.
+
+Here, then, we have that constant or constantly recurrent process of
+dispersal acting throughout long periods with varying power--that
+"continuous current of vegetation" as it has been termed, which the facts
+demand; and the extraordinary phenomenon of the species and genera of
+European and even of Arctic plants being represented abundantly in South
+America, Australia, and New Zealand, thus adds another to the long series
+of phenomena which are rendered intelligible by frequent alternations of
+warmer and colder climates in either hemisphere, culminating, at long
+intervals and in favourable situations, in actual glacial epochs.
+
+_Geological Changes as Aiding Migration._--It will be well also to notice
+here, that there is another aid to dispersion dependent upon the changes
+effected by denudation during the long periods included in the duration of
+the species and genera of plants. A considerable number of {520} the plants
+of the Miocene period of Europe were so much like existing species that
+although they have generally received fresh names they may well have been
+identical; and a large proportion of the vegetation during the whole
+Tertiary period consisted of genera which are still living.[141] But from
+what is now known of the rate of sub-aërial denudation, we are sure, that
+during each division of this period many mountain chains must have been
+considerably lowered, while we know that some of the existing ranges have
+been greatly elevated. Ancient volcanoes, too, have been destroyed by
+denudation, and new ones have been built up, so that we may be quite sure
+that ample means for the transmission of temperate plants across the
+tropics, may have existed in countries where they are now no longer to be
+found. The great mountain masses of Guiana and Brazil, for example, must
+have been far more lofty before the sedimentary covering was denuded from
+their granitic bosses and metamorphic peaks, and may have aided the
+southern migration of plants before the final elevation of the Andes. And
+if Africa presents us with an example of a continent of vast antiquity, we
+may be sure that its great central plateaux once bore far loftier mountain
+ranges before they were reduced to their present condition by long ages of
+denudation.
+
+_Proofs of Migration by Way of the Andes._--We are now prepared to apply
+the principles above laid down to the explanation of the character and
+affinities of the various portions of the north temperate flora in the
+southern hemisphere, and especially in Australia and New Zealand.
+
+At the present time the only unbroken chain of highlands and mountains
+connecting the Arctic and north temperate with the Antarctic lands is to be
+found in the American continent, the only break of importance being the
+comparatively low Isthmus of Panama, where there is {521} a distance of
+about 300 miles occupied by rugged forest-clad hills, between the lofty
+peaks of Veragua and the northern extremity of the Andes of New Grenada.
+Such distances are, as we have already seen, no barrier to the diffusion of
+plants; and we should accordingly expect that this great continuous
+mountain-chain has formed the most effective agent in aiding the southward
+migration of the Arctic and north temperate vegetation. We do find, in
+fact, not only that a large number of northern genera and many species are
+scattered all along this line of route, but that at the end of the long
+journey, in Southern Chile and Fuegia, they have established themselves in
+such numbers as to form an important part of the flora of those countries.
+From the lists given in the works already referred to, it appears that
+there are between sixty and seventy northern genera in Fuegia and Southern
+Chile, while about forty of the species are absolutely identical with those
+of Europe and the Arctic regions. Considering how comparatively little the
+mountains of South Temperate America are yet known, this is a very
+remarkable result, and it proves that the transmission of species must have
+gone on up to comparatively recent times. Yet, as only a few of these
+species are now found along the line of migration, we see that they only
+occupied such stations temporarily; and we may connect their disappearance
+with the passing away of the last glacial period which, by raising the
+snow-line, reduced the area on which alone they could exist, and exposed
+them to the competition of indigenous plants from the belt of country
+immediately below them.
+
+Now, just as these numerous species and genera have undoubtedly passed
+along the great American range of mountains, although only now found at its
+two extremes, so others have doubtless passed on further; and have found
+more suitable stations or less severe competition in the Antarctic
+continent and islands, in New Zealand, in Tasmania, and even in Australia
+itself. The route by which they may have reached these countries is easily
+marked out. Immediately south of Cape Horn, at a distance of only 500
+miles, are the South Shetland Islands and Graham's Land, whence the
+Antarctic continent or a {522} group of large islands probably extends
+across or around the south polar area to Victoria Land and thence to Adélie
+Land. The outlying Young Island, 12,000 feet high, is about 750 miles south
+of the Macquarie Islands, which may be considered a southern outlier of the
+New Zealand group; and the Macquarie Islands are about the same distance
+from the 1,000-fathom line at a point marking the probable southern
+extension of Tasmania. Other islands may have existed at intermediate
+points; but, even as it is, these distances are not greater than we know
+are traversed by plants both by flotation and by aërial currents,
+especially in such a stormy atmosphere as that of the Antarctic regions.
+Now, we may further assume, that what we know occurred within the Arctic
+circle also took place in the Antarctic--that is, that there have been
+alternations of climate during which some portion of what are now ice-clad
+lands became able to support a considerable amount of vegetation.[142]
+During such periods there would be a steady migration of plants from all
+southern circumpolar countries to people the comparatively unoccupied
+continent, and the southern extremity of America being considerably the
+nearest, and also being the best stocked with those northern types which
+have such great powers of migration and colonisation, such plants would
+form the bulk of the Antarctic vegetation, and during the continuance of
+the milder southern climate would occupy the whole area.
+
+When the cold returned and the land again became ice-clad, these plants
+would be crowded towards the outer margins of the Antarctic land and its
+islands, and some of them would find their way across the sea to such
+countries as offered on their mountain summits suitable cool stations; and
+as this process of alternately receiving plants from Chile and Fuegia and
+transmitting them in all directions from the central Antarctic land may
+have been {523} repeated several times during the Tertiary period, we have
+no difficulty in understanding the general community between the European
+and Antarctic plants found in all south temperate lands. Kerguelen's Land
+and The Crozets are within about the same distance from the Antarctic
+continent as New Zealand and Tasmania, and we need not therefore be
+surprised at finding in each of these islands some Fuegian species which
+have not reached the others. Of course, there will remain difficulties of
+detail, as there always must remain, so long as our knowledge of the past
+changes of the earth's surface and the history of the particular plants
+concerned is so imperfect. Sir Joseph Hooker notes, for example, the
+curious fact that several Compositæ common to three such remote localities
+as the Auckland Islands, Fuegia, and Kerguelen's Land, have no pappus or
+seed-down, while such as have pappus are in no case common even to two of
+these islands. Without knowing the exact history and distribution of the
+genera to which these plants belong it would be useless to offer any
+conjecture, except that they are ancient forms which may have survived
+great geographical changes, or may have some peculiar and exceptional means
+of dispersion.
+
+_Proofs of Migration by way of the Himalayas and Southern Asia._--But
+although we may thus explain the presence of a considerable portion of the
+European element in the floras of New Zealand and Australia, we cannot
+account for the whole of it by this means, because Australia itself
+contains a host of European and Asiatic genera of which we find no trace in
+New Zealand or South America, or any other Antarctic land. We find, in
+fact, in Australia two distinct sets of European plants. First we have a
+number of species identical with those of Northern Europe or Asia (of the
+most characteristic of which--thirty-eight in number--Sir Joseph Hooker
+gives a list); and in the second place a series of European genera usually
+of a somewhat more southern character, mostly represented by very distinct
+species, and all absent from New Zealand; such as Clematis, Papaver,
+Cleome, Polygala, Lavatera, Ajuga, &c. Now of the first set--the North
+European _species_--about three-fourths occur in some parts of America,
+{524} and about half in South Temperate America or New Zealand; whence we
+may conclude that most of these, as well as some others, have reached
+Australia by the route already indicated. The second set of
+Australo-European genera, however, and many others characteristic of the
+South European or the Himalayan flora, have probably reached Australia by
+way of the mountains of Southern Asia, Borneo, the Moluccas, and New
+Guinea, at a somewhat remote period when loftier ranges and some
+intermediate peaks may have existed, sufficient to carry on the migration
+by the aid of the alternate climatal changes which are known to have
+occurred. The long belt of Secondary and Palæozoic formations in East
+Australia from Tasmania to Cape York continued by the lofty ranges of New
+Guinea, indicates the route of this immigration, and sufficiently explains
+how it is that these northern types are almost wholly confined to this part
+of the Australian continent. Some of the earlier immigrants of this class
+no doubt passed over to New Zealand and now form a portion of the peculiar
+genera confined to these two countries; but most of them are of later date,
+and have thus remained in Australia only.
+
+_Proofs of Migration by way of the African Highlands._--It is owing to this
+twofold current of vegetation flowing into Australia by widely different
+routes that we have in this distant land a better representation of the
+European flora, both as regards species and genera, than in any other part
+of the southern hemisphere; and, so far as I can judge of the facts, there
+is no general phenomenon--that is, nothing in the distribution of genera
+and other groups of plants as opposed to cases of individual species--that
+is not fairly accounted for by such an origin. It further receives support
+from the case of South Africa, which also contains a large and important
+representation of the northern flora. But here we see no indications (or
+very slight ones) of that southern influx which has given Australia such a
+community of vegetation with the Antarctic lands. There are no less than
+sixty _genera_ of strictly north temperate plants in South Africa, none of
+which occur in Australia; while very few of the _species_, so
+characteristic of Australia, New Zealand, and Fuegia, are found there. It
+{525} is clear, therefore, that South Africa has received its European
+plants by the direct route through the Abyssinian highlands and the lofty
+equatorial mountains, and mostly at a distant period when the conditions
+for migration were somewhat more favourable than they are now. The much
+greater directness of the route from Northern Europe to South Africa than
+to Australia; and the existence even now of lofty mountains and extensive
+highlands for a large portion of the distance, will explain (what Sir
+Joseph Hooker notes as "a very curious fact") why South Africa has more
+very northern European _genera_ than Australia, while Australia has more
+identical _species_ and a better representation on the whole of the
+European flora--this being clearly due to the large influx of species it
+has received from the Antarctic Islands, in addition to those which have
+entered it by way of Asia. The greater distance of South Africa even now
+from any of these islands, and the much deeper sea to the south of the
+African continent, than in the case of Tasmania and New Zealand, indicating
+a smaller recent extension southward, is all quite in harmony with the
+facts of distribution of the northern flora above referred to.
+
+_Supposed Connection of South Africa and Australia._--There remains,
+however, the small amount of direct affinity between the vegetation of
+South Africa and that of Australia, New Zealand, and Temperate South
+America, consisting in all of fifteen genera, five of which are confined to
+Australia and South Africa, while several natural orders are better
+represented in these two countries than in any other part of the world.
+This resemblance has been supposed to imply some former land-connection of
+all the great southern lands, but it appears to me that any such
+supposition is wholly unnecessary. The differences between the faunas and
+floras of these countries are too great and too radical to render it
+possible that any such connection should have existed except at a very
+remote period. But if we have to go back so far for an explanation, a much
+simpler one presents itself, and one more in accordance with what we have
+learnt of the general permanence of deep oceans and the great changes that
+have taken place {526} in the distribution of all forms of life. Just as we
+explain the presence of marsupials in Australia and America and of
+Centetidæ in Madagascar and the Antilles, by the preservation in these
+localities of remnants of once wide-spread types, so we should prefer to
+consider the few genera common to Australia and South Africa as remnants of
+an ancient vegetation, once spread over the northern hemisphere, driven
+southward by the pressure of more specialised types, and now finding a
+refuge in these two widely separated southern lands. It is suggestive of
+such an explanation that these genera are either of very ancient groups--as
+Conifers and Cycads--or plants of low organisation as the Restiaceæ--or of
+world-wide distribution, as Melanthaceæ.
+
+_The Endemic Genera of Plants in New Zealand._--Returning now to the New
+Zealand flora, with which we are more especially concerned, there only
+remains to be considered the peculiar or endemic genera which characterise
+it. These are thirty-two in number, and are mostly very isolated. A few
+have affinities with Arctic groups, others with Himalayan, or Australian
+genera; several are tropical forms, but the majority appear to be
+altogether peculiar types of world-wide groups--as Leguminosæ, Saxifrageæ,
+Compositæ, Orchideæ, &c. We must evidently trace back these peculiar forms
+to the earliest immigrants, either from the north or from the south; and
+the great antiquity we are obliged to give to New Zealand--an antiquity
+supported by every feature in its fauna and flora, no less than by its
+geological structure, and its extinct forms of life[143]--affords ample
+time for the changes in the general distribution of plants, and for those
+due to isolation and modification under {527} the influence of changed
+conditions, which are manifested by the extreme peculiarity of many of
+these interesting endemic forms.
+
+_The Absence of Southern Types from the Northern Hemisphere._--We have now
+only to notice the singular want of reciprocity in the migrations of
+northern and southern types of vegetation. In return for the vast number of
+European plants which have reached Australia, not one single Australian
+plant has entered any part of the north temperate zone, and the same may be
+said of the typical southern vegetation in general, whether developed in
+the Antarctic lands, New Zealand, South America, or South Africa. The
+furthest northern outliers of the southern flora are a few genera of
+Antarctic type on the Bornean Alps; the genus Acæna which has a species in
+California; two representatives of the Australian flora--Casuarina and
+Stylidium, in the peninsula of India; while China and the Philippines have
+two strictly Australian genera of Orchideæ--Microtis and Thelymitra, as
+well as a Restiaceous genus. Several distinct causes appear to have
+combined to produce this curious inability of the southern flora to make
+its way into the northern hemisphere. The primary cause is, no doubt, the
+totally different distribution of land in the two hemispheres, so that in
+the south there is the minimum of land in the colder parts of the temperate
+zone and in the north the maximum. This is well shown by the fact that on
+the parallel of Lat. 50° N. we pass over 240° of land or shallow sea, while
+on the same parallel of south latitude we have only 4°, where we cross the
+southern part of Patagonia. Again the three most important south temperate
+land-areas--South Temperate America, South Africa, and Australia--are
+widely separated from each other, and have in all probability always been
+so; whereas the whole of the north temperate lands are practically
+continuous. It follows that, instead of the enormous northern area, in
+which highly organised and dominant groups of plants have been developed
+gifted with great colonising and aggressive powers, we have in the south
+three comparatively small and detached areas, in which rich floras have
+been developed with _special_ {528} adaptations to soil, climate, and
+organic environment, but comparatively impotent and inferior beyond their
+own domain.
+
+Another circumstance which makes the contest between the northern and
+southern forms still more unequal, is the much greater hardiness of the
+former, from having been developed in a colder region, and one where alpine
+and arctic conditions extensively prevail; whereas the southern floras have
+been mainly developed in mild regions to which they have been altogether
+confined. While the northern plants have been driven north or south by each
+succeeding change of climate, the southern species have undergone
+comparatively slight changes of this nature, owing to the areas they occupy
+being unconnected with the ice-bearing Antarctic continent. It follows,
+that whereas the northern plants find in all these southern lands a milder
+and more equable climate than that to which they have been accustomed, and
+are thus often able to grow and flourish even more vigorously than in their
+native land, the southern plants would find in almost every part of Europe,
+North America or Northern Asia, a more severe and less equable climate,
+with winters that usually prove fatal to them even under cultivation. These
+causes, taken separately, are very powerful, but when combined they must, I
+think, be held to be amply sufficient to explain why examples of the
+typical southern vegetation are almost unknown in the north temperate zone,
+while a very few of them have extended so far as the northern tropic.[144]
+
+{529}
+
+_Concluding Remarks on the Last Two Chapters._--Our inquiry into the
+external relations and probable origin of the fauna and flora of New
+Zealand, has thus led us on to a general theory as to the cause of the
+peculiar biological relations between the northern and the southern
+hemispheres; and no better or more typical example could be found of the
+wide range and great interest of the study of the geographical distribution
+of animals and plants.
+
+The solution which has here been given of one of the most difficult of this
+class of problems, has been rendered possible solely by the knowledge very
+recently obtained of the form of the sea-bottom in the southern ocean, and
+of the geological structure of the great Australian continent. Without this
+knowledge we should have nothing but a series of guesses or probabilities
+on which to found our hypothetical explanation, which we have now been able
+to build up on a solid foundation of fact. The complete separation of East
+from West Australia during a portion of the Cretaceous and Tertiary
+periods, could never have been guessed till it was established by the
+laborious explorations of the Australian geologists; while the hypothesis
+of a comparatively shallow sea, uniting New Zealand by a long route with
+tropical Australia, while a profoundly deep ocean always separated it from
+temperate Australia, would have been rejected as too improbable a
+supposition for the foundation of even the most enticing theory. Yet it is
+mainly by means of these two facts, that we are enabled to give an adequate
+explanation of the strange anomalies in the flora of Australia and its
+relation to that of New Zealand.
+
+In the more general explanation of the relations of the various northern
+and southern floras, I have shown what an important aid to any such
+explanation is the theory of repeated changes of climate, not necessarily
+of great amount, given in Chapters VIII. and IX.; while the whole
+discussion justifies the importance attached to the theory of the general
+permanence of continents and oceans, as demonstrated in Chapter VI., since
+any rational explanation based upon facts (as opposed to mere unsupported
+{530} conjecture) must take such general permanence as a starting-point.
+The whole inquiry into the phenomena presented by islands, which forms the
+main subject of the present volume has, I think, shown that this theory
+does afford a firm foundation for the discussion of questions of
+distribution and dispersal; and that by its aid, combined with a clear
+perception of the wonderful powers of dispersion and modification in the
+organic world when long periods are considered, the most difficult problems
+connected with this subject cease to be insoluble.
+
+ * * * * *
+
+
+{531}
+
+CHAPTER XXIV
+
+SUMMARY AND CONCLUSION
+
+ The Present Volume is the Development and Application of a
+ Theory--Statement of the Biological and Physical Causes of
+ Dispersal--Investigation of the Facts of Dispersal--of the Means of
+ Dispersal--of Geographical Changes Affecting Dispersal--of Climatal
+ Changes Affecting Dispersal--The Glacial Epoch and its Causes--Alleged
+ Ancient Glacial Epochs--Warm Polar Climates and their
+ Causes--Conclusions as to Geological Climates--How far Different from
+ those of Mr. Croll--Supposed Limitations of Geological Time--Time Amply
+ Sufficient both for Geological and Biological Development--Insular
+ Faunas and Floras--The North Atlantic Islands--The Galapagos--St.
+ Helena and the Sandwich Islands--Great Britain as a Recent Continental
+ Island--Borneo and Java--Japan and Formosa--Madagascar as an Ancient
+ Continental Island--Celebes and New Zealand as Anomalous Islands--The
+ Flora of New Zealand and its Origin--The European Element in the South
+ Temperate Floras--Concluding Remarks.
+
+The present volume has gone over a very wide field both of facts and
+theories, and it will be well to recall these to the reader's attention and
+point out their connection with each other, in a concluding chapter. I hope
+to be able to show that, although at first sight somewhat fragmentary and
+disconnected, this work is really the development of a clear and definite
+theory, and its application to the solution of a number of biological
+problems. That theory is, briefly, that the distribution of the various
+species and groups of living things over the earth's surface, and their
+aggregation in definite assemblages in certain areas, is the {532} direct
+result and outcome of a complex set of causes, which may be grouped as
+"biological" and "physical." The biological causes are mainly of two
+kinds--firstly, the constant tendency of all organisms to increase in
+numbers and to occupy a wider area, and their various powers of dispersion
+and migration through which, when unchecked, they are enabled to spread
+widely over the globe; and, secondly, those laws of evolution and
+extinction which determine the manner in which groups of organisms arise
+and grow, reach their maximum, and then dwindle away, often breaking up
+into separate portions which long survive in very remote regions. The
+physical causes are also mainly of two kinds. We have, first, the
+geographical changes which at one time isolate a whole fauna and flora, at
+another time lead to their dispersal and intermixture with adjacent faunas
+and floras--and it was here important to ascertain and define the exact
+nature and extent of these changes, and to determine the question of the
+general stability or instability of continents and oceans; in the second
+place, it was necessary to determine the exact nature, extent and frequency
+of the changes of climate which have occurred in various parts of the
+earth,--because such changes are among the most powerful agents in causing
+the dispersal and extinction of plants and animals. Hence the importance
+attached to the question of geological climates and their causes, which
+have been here investigated at some length with the aid of the most recent
+researches of geologists, physicists, and explorers. These various
+inquiries led on to an investigation of the mode of formation of stratified
+deposits, with a view to fix within some limits their probable age; and
+also to an estimate of the probable rate of development of the organic
+world; and both these processes are shown to involve, so far as we can
+judge, periods of time less vast than have generally been thought
+necessary.
+
+The numerous facts and theories established in the First Part of the work
+are then applied to explain the phenomena presented by the floras and
+faunas of the chief islands of the globe, which are classified, in
+accordance with their physical origin, in three groups or classes, each
+{533} of which are shown to exhibit certain well-marked biological
+features.
+
+Having thus shown that the work is a connected whole, founded on the
+principle of tracing out the more recondite causes of the distribution of
+organisms, we will briefly indicate the scope and object of the several
+chapters, by means of which this general conception has been carried out.
+
+Beginning with simple and familiar facts relating to British and European
+quadrupeds and birds, I have defined and shown the exact character of
+"areas of distribution," as applied to species, genera, and families, and
+have illustrated the subject by maps showing the peculiarities of
+distribution of some well-known groups of birds. Taking then our British
+mammals and land-birds, I follow them over the whole area they inhabit, and
+thus obtain a foundation for the establishment of "zoological regions," and
+a clear insight into their character as distinct from the usual
+geographical divisions of the globe.
+
+The facts thus far established are then shown to be necessary results of
+the "law of evolution." The nature and amount of "variation" is exhibited
+by a number of curious examples; the origin, growth, and decay of species
+and genera are traced, and all the interesting phenomena of isolated groups
+and discontinuous generic and specific areas are shown to follow as logical
+consequences.
+
+The next subject investigated is the means by which the various groups of
+animals are enabled to overcome the natural barriers which often seem to
+limit them to very restricted areas, how far those barriers are themselves
+liable to be altered or abolished, and what is the exact nature and amount
+of the changes of sea and land which our earth has undergone in past times.
+This latter part of the inquiry is shown to be the most important as it is
+the most fundamental; and as it is still a subject of controversy, and many
+erroneous views prevail in regard to it, it is discussed at some length.
+Several distinct classes of evidence are adduced to prove that the grand
+features of our globe--the position of the great oceans {534} and the chief
+land-areas--have remained, on the whole, unchanged throughout geological
+time. Our continents are shown to be built up mainly of "shore-deposits";
+and even the chalk, which is so often said to be the exact equivalent of
+the "globigerina ooze" now forming in mid-Atlantic, is shown to be a
+comparatively shallow-water deposit formed in inland seas, or in the
+immediate vicinity of land. The general stability of continents has,
+however, been accompanied by constant changes of form, and insular
+conditions have prevailed over every part in succession; and the effect of
+such changes on the distribution of organisms is pointed out.
+
+We then approach the consideration of another set of changes--those of
+climate--which have probably been agents of the first importance in
+modifying the specific forms as well as the distribution of animals. Here
+again we find ourselves in the midst of fierce controversies. The
+occurrence of a recent glacial epoch of great severity in the northern
+hemisphere is now universally admitted, but the causes which brought it on
+are matter of dispute. But unless we can arrive at these causes, as well as
+at those which produced the equally well demonstrated mild climate in the
+Arctic regions, we shall be quite unable to determine the nature and amount
+of the changes of climate which have occurred throughout past ages, and
+shall thus be left without a most important clue to the explanation of many
+of the anomalies in the distribution of animals and plants.
+
+I have therefore devoted three chapters to a full investigation of this
+question. I have first given such a sketch of the most salient facts as to
+render the phenomena of the glacial epoch clear and intelligible. I then
+review the various suggested explanations, and, taking up the two which
+alone seem tenable, I endeavour to determine the true principles of each.
+While adopting generally Mr. Croll's views as to the causes of the "glacial
+epoch," I have introduced certain limitations and modifications. I have
+pointed out, I believe, more clearly than has hitherto been done, the very
+different effects on climate of water in the liquid and in the solid state;
+and I have {535} shown, by a variety of evidence, that without high land
+there can be no permanent snow and ice. From these facts and principles the
+very important conclusion is reached, that the alternate phases of
+precession--causing the winter of each hemisphere to be in _aphelion_ and
+_perihelion_ each 10,500 years--would produce a complete change of climate
+only where a country was _partially_ snow-clad; while, whenever a large
+area became almost _wholly_ buried in snow and ice--as was certainly the
+case with Northern Europe and America during the glacial epoch--then the
+glacial conditions would be continued and perhaps even intensified when the
+sun approached nearest to the earth in winter, instead of there being at
+that time, as Mr. Croll maintains, an almost perpetual spring. This
+important result is supported by reference to the existing differences
+between the climates of the northern and southern hemispheres, and by what
+is known to have occurred during the last glacial epoch; and it is shown to
+be in complete harmony with the geological evidence as to interglacial mild
+periods.
+
+Discussing next the evidence for glacial epochs in earlier times, it is
+shown that Mr. Croll's views are opposed by a vast body of facts, and that
+the geological evidence leads irresistibly to the conclusion that during a
+large portion of the Secondary and Tertiary periods, uninterrupted warm
+climates prevailed in the north temperate zone, and so far ameliorated the
+climate of the Arctic regions as to admit of the growth of a luxuriant
+vegetation in the highest latitudes yet explored. The geographical
+condition of the northern hemisphere at these periods is then investigated,
+and it is shown to have been probably such as to admit the warm tropical
+waters freely to penetrate the land, and to reach the Arctic seas by
+several channels; and, adopting Mr. Croll's calculations as to the enormous
+quantity of heat that would thus be conveyed northwards, it is maintained
+that the mild Arctic climates are amply accounted for. With such favourable
+geographical conditions, it is shown, that changes of excentricity and of
+the phases of precession would have no other effect than to cause greater
+differences {536} of temperature between summer and winter; but, wherever
+there was a considerable extent of very lofty mountains the snow-line would
+be lowered, and the snow-collecting area being thus largely increased a
+considerable amount of local glaciation might result. Thus may be explained
+the presence of enormous ice-borne rocks in Eocene and Miocene times in
+Central Europe, while at the very same period all the surrounding country
+enjoyed a tropical or sub-tropical climate.
+
+The general conclusion is thus reached, that geographical conditions are
+the essential causes of great changes of climate, and that the radically
+different distribution of land and sea in the northern and southern
+hemispheres has generally led to great diversity of climate in the Arctic
+and Antarctic regions. The form and arrangement of the continents is shown
+to be such as to favour the transfer of warm oceanic currents to the north
+far in excess of those which move towards the south, and whenever these
+currents had free passage _through_ the northern land-masses to the polar
+area, a mild climate must have prevailed over the whole northern
+hemisphere. It is only in very recent times that the great northern
+continents have become so completely consolidated as they now are, thus
+shutting out the warm water from their interiors, and rendering possible a
+wide-spread and intense glacial epoch. But this great climatal change was
+actually brought about by the high excentricity which occurred about
+200,000 years ago; and it is doubtful if a similar glaciation in equally
+low latitudes could be produced by means of any such geographical
+combinations as actually occur, without the concurrence of a high
+excentricity.
+
+A survey of the present condition of the earth supports this view, for
+though we have enormous mountain ranges in every latitude, there is no
+glaciated country south of Greenland in N. Lat. 61°. But directly we go
+back a very short period, we find the superficial evidences of glaciation
+to an enormous extent over three-fourths of the globe. In the Alps and
+Pyrenees, in the British Isles and Scandinavia, in Spain and the Atlas, in
+the Caucasus {537} and the Himalayas, in Eastern North America and west of
+the Rocky Mountains, in the Andes of South Temperate America, in South
+Africa, and in New Zealand, huge moraines and other unmistakable ice-marks
+attest the universal descent of the snow-line for several thousand feet
+below its present level. If we reject the influence of high excentricity as
+the cause of this almost universal glaciation, we must postulate a general
+elevation of _all_ these mountains about the same time, geologically
+speaking--for the general similarity in the state of preservation of the
+ice-marks and the known activity of denudation as a destroying agent,
+forbid the idea that they belong to widely separated epochs. It has,
+indeed, been suggested, that denudation alone has lowered these mountains
+so much during the post-tertiary epoch, that they were previously of
+sufficient height to account for the glaciation of all of them; but this
+hardly needs refutation, for it is clear that denudation could not at the
+same time have removed some thousands of feet of rock from many hundreds of
+square miles of lofty snow-collecting plateaus, and yet have left moraines,
+and blocks, and even glacial striæ, undisturbed and uneffaced on the slopes
+and in the valleys of these same mountains.
+
+The theory of geological climates set forth in this volume, while founded
+on Mr. Croll's researches, differs from all that have yet been made public,
+in clearly tracing out the comparative influence of geographical and
+astronomical revolutions, showing that, while the former have been the
+chief, if not the exclusive, causes of the long-continued mild climates of
+the Arctic regions, the concurrence of the latter has been essential to the
+production of glacial epochs in the temperate zones, as well as of those
+local glaciations in low latitudes, of which there is such an abundance of
+evidence.
+
+The next question discussed is that of geological time as bearing on the
+development of the organic world. The periods of time usually demanded by
+geologists have been very great, and it was often assumed that there was no
+occasion to limit them. But the theory of development demands far more; for
+the earliest fossiliferous rocks {538} prove the existence of many and
+varied forms of life which require unrecorded ages for their
+development--ages probably far longer than those which have elapsed from
+that period to the present day. The physicists, however, deny that any such
+indefinitely long periods are available. The sun is ever losing heat far
+more rapidly than it can be renewed from any known or conceivable source.
+The earth is a cooling body, and must once have been too hot to support
+life; while the friction of the tides is checking the earth's rotation, and
+this cannot have gone on indefinitely without making our day much longer
+than it is. A limit is therefore placed to the age of the habitable earth,
+and it has been thought that the time so allowed is not sufficient for the
+long processes of geological change and organic development. It is
+therefore important to inquire whether these processes are either of them
+so excessively slow as has been supposed, and I devote a chapter to the
+inquiry.
+
+Geologists have measured with some accuracy the maximum thickness of all
+the known sedimentary rocks. The rate of denudation has also been recently
+measured by a method which, if not precise, at all events gives results of
+the right order of magnitude and which err on the side of being too slow
+rather than too fast. If, then, the _maximum_ thickness of the _known_
+sedimentary rocks is taken to represent the _average_ thickness of _all_
+the sedimentary rocks, and we also know the _amount_ of sediment carried to
+the sea or lakes, and the _area_ over which that sediment is spread, we
+have a means of calculating the _time_ required for the building up of all
+the sedimentary rocks of the geological system. I have here inquired how
+far the above suppositions are correct, or on which side they probably err;
+and the conclusion arrived at is, that the time required is very much less
+than has hitherto been supposed.
+
+Another estimate is afforded by the date of the last glacial epoch if
+coincident with the last period of high excentricity, while the Alpine
+glaciation of the Miocene period is assumed to have been caused by the next
+earlier phase of very high excentricity. Taking these as data, the {539}
+proportionate change of the species of mollusca affords a means of arriving
+at the whole lapse of time represented by the fossiliferous rocks; and
+these two estimates agree in the _order_ of their magnitudes.
+
+It is then argued that the changes of climate every 10,500 years during the
+numerous periods of high excentricity have acted as a motive power in
+hastening on both geological and biological change. By raising and lowering
+the snow-line in all mountain ranges it has caused increased denudation;
+while the same changes have caused much migration and disturbance in the
+organic world, and have thus tended to the more rapid modification of
+species. The present epoch being a period of very low excentricity, the
+earth is in a phase of _exceptional stability_ both physical and organic;
+and it is from this period of exceptional stability that our notions of the
+very slow rate of change have been derived.
+
+The conclusion is, on the whole, that the periods allowed by physicists are
+not only far in excess of such as are required for geological and organic
+change, but that they allow ample margin for a lapse of time anterior to
+the deposit of the earliest fossiliferous rocks several times longer than
+the time which has elapsed since their deposit to the present day.
+
+Having thus laid the foundation for a scientific interpretation of the
+phenomena of distribution, we proceed to the Second Part of our work--the
+discussion of a series of typical Insular Faunas and Floras with a view to
+explain the interesting phenomena they present. Taking first two North
+Atlantic groups--the Azores and Bermuda--it is shown how important an agent
+in the dispersal of most animals and plants is a stormy atmosphere.
+Although 900 and 700 miles respectively from the nearest continents, their
+productions are very largely identical with those of Europe and America;
+and, what is more important, fresh arrivals of birds, insects, and plants,
+are now taking place almost annually. These islands afford, therefore, test
+examples of the great dispersive powers of certain groups of organisms, and
+thus serve as a basis on which to found our explanations of many anomalies
+of distribution. Passing {540} on to the Galapagos we have a group less
+distant from a continent and of larger area, yet, owing to special
+conditions, of which the comparatively stormless equatorial atmosphere is
+the most important, exhibiting far more speciality in its productions than
+the more distant Azores. Still, however, its fauna and flora are as
+unmistakably derived from the American continent as those of the Azores are
+from the European.
+
+We next take St. Helena and the Sandwich Islands, both wonderfully isolated
+in the midst of vast oceans, and no longer exhibiting in their productions
+an exclusive affinity to one continent. Here we have to recognise the
+results of immense antiquity, and of those changes of geography, of
+climate, and in the general distribution of organisms which we know have
+occurred in former geological epochs, and whose causes and consequences we
+have discussed in the first part of our volume. This concludes our review
+of the Oceanic Islands.
+
+Coming now to Continental Islands we consider first those of most recent
+origin and offering the simplest phenomena; and begin with the British
+Isles as affording the best example of very recent and well known
+Continental Islands. Reviewing the interesting past history of Britain, we
+show why it is comparatively poor in species and why this poverty is still
+greater in Ireland. By a careful examination of its fauna and flora it is
+then shown that the British Isles are not so completely identical,
+biologically, with the continent as has been supposed. A considerable
+amount of speciality is shown to exist, and that this speciality is real
+and not apparent is supported by the fact, that small outlying islands,
+such as the Isle of Man, the Shetland Isles, Lundy Island, and the Isle of
+Wight, all possess certain species or varieties not found elsewhere.
+
+Borneo and Java are next taken, as illustrations of tropical islands which
+may be not more ancient than Britain, but which, owing to their much larger
+area, greater distance from the continent, and the extreme richness of the
+equatorial fauna and flora, possess a large proportion of peculiar species,
+though these are in general very closely allied to those of the adjacent
+parts of Asia. The {541} preliminary studies we have made enable us to
+afford a simpler and more definite interpretation of the peculiar relations
+of Java to the continent and its differences from Borneo and Sumatra, than
+was given in my former work (_The Geographical Distribution of Animals_).
+
+Japan and Formosa are next taken, as examples of islands which are
+decidedly somewhat more ancient than those previously considered, and which
+present a number of very interesting phenomena, especially in their
+relations to each other, and to remote rather than to adjacent parts of the
+Asiatic continent.
+
+We now pass to the group of Ancient Continental Islands, of which
+Madagascar is the most typical example. It is surrounded by a number of
+smaller islands which may be termed its satellites since they partake of
+many of its peculiarities; though some of these--as the Comoros and
+Seychelles--may be considered continental, while others--as Bourbon,
+Mauritius, and Rodriguez--are decidedly oceanic. In order to understand the
+peculiarities of the Madagascar fauna we have to consider the past history
+of the African and Asiatic continents, which it is shown are such as to
+account for all the main peculiarities of the fauna of these islands
+without having recourse to the hypothesis of a now-submerged Lemurian
+continent. Considerable evidence is further adduced to show that "Lemuria"
+is a myth, since not only is its existence unnecessary, but it can be
+proved that it would not explain the actual facts of distribution. The
+origin of the interesting Mascarene wingless birds is discussed, and the
+main peculiarities of the remarkable flora of Madagascar and the Mascarene
+islands pointed out; while it is shown that all these phenomena are to be
+explained on the general principles of the permanence of the great oceans
+and the comparatively slight fluctuations of the land area, and by taking
+account of established palæontological facts.
+
+There remain two other islands--Celebes and New Zealand--which are classed
+as "anomalous," the one because it is almost impossible to place it in any
+of the six zoological regions, or determine whether it has ever been
+actually joined to a continent--the other because it {542} combines the
+characteristics of continental and oceanic islands.
+
+The peculiarities of the Celebesian fauna have already been dwelt upon in
+several previous works, but they are so remarkable and so unique that they
+cannot be omitted in a treatise on "Insular Faunas"; and here, as in the
+case of Borneo and Java, fuller consideration and the application of the
+general principles laid down in our First Part, lead to a solution of the
+problem at once more simple and more satisfactory than any which have been
+previously proposed. I now look upon Celebes as an outlying portion of the
+great Asiatic continent of Miocene times, which either by submergence or
+some other cause had lost the greater portion of its animal inhabitants,
+and since then has remained more or less completely isolated from every
+other land. It has thus preserved a fragment of a very ancient fauna along
+with a number of later types which have reached it from surrounding islands
+by the ordinary means of dispersal. This sufficiently explains all the
+peculiar _affinities_ of its animals, though the peculiar and distinctive
+_characters_ of some of them remain as mysterious as ever.
+
+New Zealand is shown to be so completely continental in its geological
+structure, and its numerous wingless birds so clearly imply a former
+connection with some other land (as do its numerous lizards and its
+remarkable reptile, the Hatteria), that the total absence of indigenous
+land-mammalia was hardly to be expected. Some attention is therefore given
+to the curious animal which has been seen but never captured, and this is
+shown to be probably identical with an animal referred to by Captain Cook.
+The more accurate knowledge which has recently been obtained of the sea
+bottom around New Zealand enables us to determine that the former
+connection of that island with Australia was towards the north, and this is
+found to agree well with many of the peculiarities of its fauna.
+
+The flora of New Zealand and that of Australia are now both so well known,
+and they present so many peculiarities, and relations of so anomalous a
+character, {543} as to present in Sir Joseph Hooker's opinion an almost
+insoluble problem. Much additional information on the physical and
+geological history of these two countries has, however, been obtained since
+the appearance of Sir Joseph Hooker's works, and I therefore determined to
+apply to them the same method of discussion and treatment which has been
+usually successful with similar problems in the case of animals. The fact
+above noted, that New Zealand was connected with Australia in its northern
+and tropical portion only, of itself affords a clue to one portion of the
+specialities of the New Zealand flora--the presence of an unusual number of
+tropical families and genera, while the temperate forms consist mainly of
+species either identical with those found in Australia or closely allied to
+them. But a still more important clue is obtained in the geological
+structure of Australia itself, which is shown to have been for long periods
+divided into an eastern and a western island, in the latter of which the
+highly peculiar flora of temperate Australia was developed. This is found
+to explain with great exactness the remarkable absence from New Zealand of
+all the most abundant and characteristic Australian genera, both of plants
+and of animals, since these existed at that time only in the _western_
+island, while New Zealand was in connection with the _eastern_ island alone
+and with the tropical portion of it. From these geological and physical
+facts, and the known powers of dispersal of plants, all the main features,
+and many of the detailed peculiarities of the New Zealand flora are shown
+necessarily to result.
+
+Our last chapter is devoted to a wider, and if possible more interesting
+subject--the origin of the European element in the floras of New Zealand
+and Australia, and also in those of South America and South Africa. This is
+so especially a botanical question, that it was with some diffidence I
+entered upon it, yet it arose so naturally from the study of the New
+Zealand and Australian floras, and seemed to have so much light thrown upon
+it by our preliminary studies as to changes of climate and the causes which
+have favoured the distribution of plants, that I felt my work would be
+incomplete without a consideration of {544} it. The subject will be so
+fresh in the reader's mind that a complete summary of it is unnecessary. I
+venture to think, however, that I have shown, not only the several routes
+by which the northern plants have reached the various southern lands, but
+have pointed out the special aids to their migration, and the motive power
+which has urged them on.
+
+In this discussion, if nowhere else, will be found a complete justification
+of that lengthy investigation of the exact nature of past changes of
+climate, which to some readers may have seemed unnecessary and unsuited to
+such a work as the present. Without the clear and definite conclusions
+arrived at by that discussion, and those equally important views as to the
+permanence of the great features of the earth's surface, and the wonderful
+dispersive powers of plants which have been so frequently brought before us
+in our studies of insular floras, I should not have ventured to attack the
+wide and difficult problem of the northern element in southern floras.
+
+
+
+In concluding a work dealing with subjects which have occupied my attention
+for many years, I trust that the reader who has followed me throughout will
+be imbued with the conviction that ever presses upon myself, of the
+complete interdependence of organic and inorganic nature. Not only does the
+marvellous structure of each organised being involve the whole past history
+of the earth, but such apparently unimportant facts as the presence of
+certain types of plants or animals in one island rather than in another,
+are now shown to be dependent on the long series of past geological
+changes--on those marvellous astronomical revolutions which cause a
+periodic variation of terrestrial climates--on the apparently fortuitous
+action of storms and currents in the conveyance of germs--and on the
+endlessly varied actions and reactions of organised beings on each other.
+And although these various causes are far too complex in their combined
+action to enable us to follow them out in the case of any one species, yet
+their broad results are clearly recognisable; and we are thus encouraged to
+study more completely every detail and {545} every anomaly in the
+distribution of living things, in the firm conviction that by so doing we
+shall obtain a fuller and clearer insight into the course of nature, and
+with increased confidence that the "mighty maze" of Being we see everywhere
+around us is "not without a plan."
+
+{549}
+
+ INDEX
+
+ A.
+ Acacia, wide range of in Australia, 185
+ _Acacia heterophylla_, and _Acacia koa_, 443
+ Acæna in California, 527
+ _Accipiter hawaii_, 314
+ Achatinellinæ, average range of, 317
+ _Ægialitis sanctæ-helenæ_, 305
+ Africa, characteristic mammalia of, 416
+ former isolation of, 418
+ Africa and Madagascar, relations of, 418
+ early history of, 419
+ African highlands as aiding the migration of plants, 524
+ African reptiles absent from Madagascar, 418
+ Aggressive power of the Scandinavian flora, 511
+ Air and water, properties of, in relation to climate, 131
+ _Alectorænas pulcherrimus_, 429
+ Allen, Mr. J. A., on variation, 58
+ Allied species occupy separate areas, 478
+ Alpine plants, their advantages as colonisers, 503
+ Alternations of climate in Switzerland and North America, 121
+ Alternations of climate, palæontological evidence of, 119
+ Amazon, limitation of species by, 18
+ _Amblyrhynchus cristatus_, 279
+ American genera of reptiles in Madagascar, 417
+ Amphibia, dispersal of, 76
+ of the Seychelles, 432
+ introduced, of Mauritius, 435
+ of New Zealand, 483
+ Amphioxus, 63
+ Amphisbænidæ, 28
+ _Amydrus Tristramii_, restricted range of, 16
+ _Anas Wyvilliana_, 314
+ Ancient continental islands, 244, 411
+ Ancient glacial epochs, 169
+ what evidence of may be expected, 175
+ Ancient groups in Madagascar, 419
+ Andersson, N. J., on the flora of the Galapagos, 287
+ Andes, migration of plants along the, 520
+ _Angræcum sesquipedale_, 440
+ Animal life, effects of glacial epoch on, 117
+ Animal life of Formosa, 401
+ _Anoa depressicornis_, 456
+ Antarctic continent as a means of plant-dispersion, 521
+ Antarctic islands, with perpetual snow, 136
+ Antelopes, overlapping genera of, 29
+ Antiquity of Hawaiian fauna and flora, 328
+ of land-shells, 79
+ of New Zealand, 526
+ of plants as affecting their dispersal, 82
+ _Apera arundinacea_, 503
+ _Apium graveolens_ in New Zealand, 515
+ Apteryx, species of, 476
+ _Arabis hirsuta_ on railway arch, 514
+ Archaic forms still existing, 229
+ Arctic and Antarctic regions, contrasts of, 135
+ Arctic current, effects of a stoppage of, 150
+ Arctic plants in the southern hemisphere, 509
+ Arctic regions, mild climates of, 181
+ recent interglacial mild period in, 182
+ Arctic warm climates of Secondary and Palæozoic times, 201
+ Areas of distribution, 13
+ separate and overlapping, 17, 28
+ Ascension, former climate and productions of, 303
+ Astronomical and geographical causes, comparative effects of, on climate,
+ 207
+ Astronomical causes of change of climate, 126
+ of glaciation, 140
+ Atlantic isles, peculiar mosses of, 368
+ Atlantosaurus, the largest land-animal, 98
+ _Atriplex patula_ on a railway bank, 515
+ Auchenia, 27
+ Austen, Mr. Godwin, on littoral shells in deep water, 337
+ Australia, two sets of Northern plants in, 523
+ South European plants in, 523
+ Australia and South Africa, supposed connection of, 525
+ {550}
+ Australian Alps, indications of glaciation in, 163
+ birds absent from New Zealand, 483
+ flora, general features of, 491
+ richest in temperate zone, 491
+ recent and derivative in the tropics, 492
+ its south-eastern and south-western divisions, 493
+ Sir Joseph Hooker on, 494
+ geological explanation of, 494
+ its presence in New Zealand, 498
+ natural orders of, wanting in New Zealand, 490
+ orchideæ in China, 527
+ genera of plants in India, 524
+ plants absent from New Zealand, 488, 490
+ none in north temperate zone, 527
+ running wild in Neilgherrie mountains, 528
+ region, definition of, 45
+ mammals and birds of, 46
+ seeds scattered in New Zealand, 508
+ Aylward, Captain, on glaciation of South Africa, 163
+ Azores, 247
+ absence from, of large-fruited trees or shrubs, 260
+ zoological features of, 248
+ birds of, 249
+ insects of, 253
+ beetles of, 253
+ land-shells of, 256
+ flora of, 256
+ Azores and New Zealand, identical plants in both, 512
+ Azorean bird-fauna, origin of, 250
+ fauna and flora, deductions from, 261
+ plants, facilities for the dispersal of, 260
+
+ B.
+ _Babirusa alfurus_ in Celebes, 456
+ Badgers, 41
+ Bahamas contrasted with Florida, 5
+ Baker, Mr., on flora of Mauritius and the Seychelles, 441
+ Bali and Lombok, contrasts of, 4
+ Banca, peculiar species of, 386
+ _Barbarea precox_ on railway bank, 514
+ Barn-owl, wide range of, 15
+ Baron, Rev. R., on the flora of Madagascar, 441
+ Barriers to dispersal, 73
+ Batrachia, 30
+ Bats in Bermuda, 269
+ Bears of Europe and America, 14
+ Beaver of Europe and America, 14
+ Beetles of the Azores, 253
+ remote affinities of some of, 255
+ of the Galapagos, 284
+ of St. Helena, 298
+ of the Sandwich Islands, 318
+ peculiar British species of, 351
+ Bell-birds, distribution of, 24
+ Bennett, Mr. Arthur, on peculiar British plants, 360
+ on the vegetation of railway banks, 514
+ Bentham, Mr., on the compositæ of the Galapagos, 288
+ on the compositæ of St. Helena, 307
+ on the Mascarene compositæ, 445
+ on Sandwich Island compositæ, 325
+ Bermuda, 262
+ soundings around, 263
+ red clay of, 265
+ zoology of, 266
+ reptiles of, 266
+ birds of, 266
+ insects of, 269
+ land-mollusca of, 270
+ flora of, 271
+ Bermuda and Azores, comparison of bird-faunas of, 268
+ _Bernicla sandvichensis_, 314
+ Biological causes which determine distribution, 532
+ Biological features of Madagascar, 416
+ Birds as plant-dispersers, 81
+ as seed-carriers, 81, 258
+ common to Great Britain and Japan, 396
+ common to India and Japan, 399
+ specific range of, 15
+ range of British, 34
+ range of East Asian, 38
+ variation in N. American, 58
+ dispersal of, 75
+ of the Azores, 249
+ of Bermuda, 266
+ of Bermuda and Azores compared, 268
+ of the Galapagos, 280
+ of the Sandwich Islands, 313
+ peculiar to Britain, 340
+ of Borneo, 377
+ of Java, 382
+ of the Philippines, 388
+ of Japan, 396
+ peculiar to Japan, 398
+ peculiar to Formosa, 404
+ common to Formosa and India or Malaya, 407
+ of Madagascar, and their teachings, 422
+ of Comoro Islands, 429
+ of the Seychelles, 430
+ of the Mascarene islands, 436
+ of islands east and west of Celebes, 454
+ of Celebes, 458
+ peculiar to Celebes, 459
+ Himalayan types of, in Celebes, 462
+ list of, in Celebes, 466
+ of New Zealand, 476, 482
+ wingless, of New Zealand, 476
+ Blackburn, Mr. T., on the beetles of the Sandwich Islands, 318
+ Blakiston and Pryer on birds of Japan, 396
+ {551}
+ Bland, Mr., on land-shells of Bermuda, 270
+ Blanford, Mr. W. T., on small effect of marine denudation, 225
+ Blanford, Mr. H. F., on former connection of Africa and India, 426
+ Blocks, travelled and perched, 109
+ Blue magpies, range of, 15
+ Borneo, geology of, 375
+ mammalia of, 376
+ birds of, 377
+ affinities of fauna of, 381
+ Borneo and Asia, resemblance of, 6
+ Borneo and Java, 373
+ Boulder-beds of the carboniferous formation, 201
+ Boulder clays of east of England, 118
+ Bovidæ, 29
+ Brady, Mr. H. B., on habitat of globigerinæ, 92
+ Braithwaite, Dr. R., on peculiar British mosses, 365
+ Britain, probable climate of, with winter in _aphelion_, 156
+ British birds, range of, 34-38
+ British Columbia, interglacial warm periods in, 121
+ British fauna and flora, peculiarities of, 370
+ British Isles, recent changes in, 332
+ proofs of former elevation of, 334
+ submerged forests of, 335
+ buried river channels of, 336
+ last union of, with continent, 337
+ why poor in species, 338
+ peculiar birds of, 339
+ fresh-water fishes of, 340
+ peculiar insects of, 344
+ peculiar Lepidoptera of, 347
+ peculiar Coleoptera of, 351
+ peculiar Trichoptera of, 355
+ peculiar land and fresh-water shells of, 356
+ peculiarities of the flora of, 360
+ peculiar mosses and Hepaticæ of, 366
+ British mammals as indicating a zoological region, 33
+ Buller, Sir W. L., on the New Zealand rat, 475
+ Buried river-channels, 336
+ _Buteo solitarius_, 314
+ Butterflies of Celebes, peculiar shape of, 463
+ Butterflies, peculiar British, 347
+
+ C.
+ Caddis-flies peculiar to Britain, 355
+ Cæcilia, species of, in the Seychelles, 432
+ wide distribution of, 432
+ Cæciliadæ, 28
+ _Callithea Leprieuri_, distribution of, 18
+ _Callithea sapphira_, 18
+ Camels as destroyers of vegetation, 296
+ former wide distribution of, 421
+ Camelus, 17, 27
+ _Campanula vidalii_, 261
+ Canis, 17, 26
+ Carabus, numerous species of, 42
+ Carboniferous boulder-beds, 201
+ warm Arctic climate, 201
+ Carnivora in Madagascar, 417
+ Carpenter, Dr., on habitat of globigerinæ, 92
+ Carpenter, Mr. Edward, on Mars and glacial periods, 164
+ _Carduus marianus_ in New Zealand, 515
+ _Carpodacus purpureus_ and _P. californicus_, 68
+ Castor, 17
+ Casuarina, 185
+ in India, 527
+ Cause of extinction, 63
+ Caves of Glamorganshire, 336
+ Cebibæ, overlapping genera of, 29
+ Celebes, physical features of, 451
+ islands around, 452
+ zoology of, 455
+ derivation of mammals of, 457
+ birds of, 458
+ not a continental island, 461
+ insect peculiarities of, 462
+ Himalayan types in, 462
+ peculiarity of butterflies of, 463
+ list of land-birds of, 466
+ Centetidæ, 27
+ Centetidæ, formerly inhabited Europe, 420
+ Central America, mixed fauna of, 53
+ Ceratodus, or mud-fish, 69
+ Cervus, 17, 26
+ Chalk a supposed oceanic formation, 89
+ Chalk at Oahu, analysis of, 90
+ Chalk, analysis of, 91
+ Chalk mollusca indicative of shallow water, 93
+ Chalk sea, extent of, in Europe, 93
+ Chalk-formation, land-plants found in, 94
+ deposited in an inland sea, 93
+ of Faxoe an ancient coral-reef, 94
+ modern formation of, 95
+ supposed oceanic origin of, erroneous, 96
+ "Challenger" soundings and shore-deposits, 86
+ "Challenger" ridge in the Atlantic, 101
+ Chameleons very abundant in Madagascar, 430
+ Chamois, distribution of, 13
+ Changes of land and sea, 83
+ Chasmorhynchus, distribution of, 24
+ _C. nudicollis_, 24
+ _C. tricarunculatus_, 24
+ _C. variegatus_, 24
+ _C. niveus_, 24
+ _Chilomenus lunata_, 300
+ Chinchillas, 26
+ Chrysochloridæ, 29
+ Cicindela, 17
+ Cicindelidæ common to South America and Madagascar, 28
+ Clay, red, of Bermuda, 265
+ Climate, astronomical causes of changes of, 126
+ {552}
+ properties of snow and ice in relation to, 131
+ of Britain with winter in _aphelion_, 156
+ of Tertiary period in Europe and N. America, 178
+ temperate in Arctic regions, 181
+ causes of mild Arctic, 190
+ of Tertiary and Secondary periods, 199, 202
+ of the Secondary and Palæozoic epochs, 200
+ change of, during Tertiary and Secondary Periods, 200
+ affected by arrangement of the great continents, 205
+ nature of changes of, caused by high excentricity, 230
+ exceptional stability of the present, 232
+ changes of, as affecting migration of plants, 517
+ Climatal changes, 106
+ change, its essential principle restated, 158
+ changes as modifying organisms, 229
+ Clouds cut off the sun's heat, 145
+ Coal in Sumatra, 385
+ Coast line of globe, extent of, 221
+ Cochoa, distribution of, 25
+ Cockerell, Mr. Th. D. A., on slugs of Bermuda, 271
+ on British land and fresh-water shells, 356
+ Cold alone does not cause glaciation, 135
+ how it can be stored up, 133
+ Coleoptera of the Azores, 253
+ of St. Helena, 298
+ of the Sandwich Islands, 318
+ peculiar British species of, 351
+ Comoro Islands, 428
+ mammals and birds of, 428
+ Compositæ of the Galapagos, 288
+ of St. Helena, 307
+ of the Sandwich Islands, 325
+ of the Mascarene Islands, 445
+ species often have restricted ranges, 504
+ Conclusions on the New Zealand flora, 506
+ Contemporaneous formation of Lower Greensand and Wealden, 221
+ Continental conditions throughout geological time, 97-99
+ changes and animal distribution, 102
+ extensions will not explain anomalous facts of distribution, 449
+ Continental islands, 243
+ of recent origin, 331
+ general remarks on recent, 408
+ ancient, 411
+ Continental period, date of, 337
+ Continents, movements of, 88
+ permanence of, 97
+ general stability of, 101, 103
+ geological development of, 205
+ Continuity of land, 74
+ Continuity of now isolated groups, proof of, 70
+ Cook, Captain, on a native quadruped in New Zealand, 476
+ Cope, Professor, on the Bermuda lizard, 266
+ _Coracias temminckii_, in Celebes, 463
+ Corvus, 17
+ Cossonidæ, in St. Helena, 299
+ Cretaceous deposits in North Australia, 493, 496
+ Cretaceous flora of Greenland, 185
+ of the United States, 189
+ Croll, Dr. James, on Antarctic icebergs, 136
+ on winter temperature of Britain in glacial epoch, 141
+ on diversion of gulf-stream during the glacial epoch, 143
+ on loss of heat by clouds and fogs, 145
+ on geographical causes as affecting climate, 148
+ on ancient glacial epochs, 170
+ on universality of glacial markings in Scotland, 174
+ on mild climates of Arctic regions, 189
+ on ocean-currents, 190, 204
+ on age of the earth, 213
+ on mean thickness of sedimentary rocks, 220
+ on small amount of marine denudation, 225
+ on buried river-channels, 336
+ Ctenodus, 69
+ Cyanopica, distribution of, 24
+ _Cyanopica cooki_, restricted range of, 15, 24
+ _Cyanopica cyanus_, 24
+ _Cynopithecus nigrescens_, in Celebes, 456
+
+ D.
+ Dacelo, 47
+ Dana on continental upheavals, 88
+ on chalk in the Sandwich Islands, 90
+ on elevation of land causing the glacial epoch, 152
+ on elevation of Western America, 194
+ on the development of continents, 205
+ on shore-deposits, 222
+ on life extermination by cold epochs, 230
+ Darwin, experiment on _Helix pomatia_, 78
+ on the permanence of oceans, 100
+ on cloudy sky of Antarctic regions, 146
+ on glaciers of the Southern Andes, 147
+ on geological time, 211
+ on complex relations of organisms, 226
+ on oceanic islands, 242
+ on seeds carried by birds, 257
+ {553}
+ experiments on seed-dispersal, 258
+ on natural history of the Keeling Islands, 286
+ theory of formation of atolls, 397
+ on cultivated plants not running wild, 507
+ Dawkins, Professor Boyd, on animal migrations during the glacial epoch,
+ 120
+ Dawson, Mr. G. M., on alternations of climate in British Columbia, 121
+ Professor, on Palæozoic boulder-beds in Nova Scotia, 201
+ De Candolle on dispersal of seeds, 80
+ Deep-sea deposits, 219
+ Deer in Celebes, 456
+ _Delphinium ajacis_, on a railway bank, 515
+ _Dendroeca_, 19
+ _D. coerulea_, 19
+ _D. discolor_, 19
+ _D. dominica_, 19
+ _Dendroeca coronata_, variation of, 58
+ Dendrophidæ, 29
+ Denudation destroys the evidences of glaciation, 172
+ Denudation and deposition as a measure of time, 213
+ Denudation in river basins, measurement of, 215
+ Denudation, marine as compared with sub-aerial, 225
+ Deposition of sediments, how to estimate the average, 221
+ Deserts, cause of high temperature of, 132
+ Diagram of excentricity and precession, 129
+ Diagram of excentricity for three million years, 171
+ Dididæ, how exterminated, 436
+ Didunculus, keeled sternum of, 437
+ Diospyros, in upper greensand of Greenland, 186
+ _Diplotaxis muralis_, on railway banks, 513
+ Dipnoi, discontinuity of, 69
+ Dipterus, 69
+ Discontinuity among North American birds, 67
+ Discontinuity a proof of antiquity, 69
+ Discontinuous generic areas, 23
+ Discontinuous areas, 64
+ why rare, 64
+ Dispersal of animals, 72
+ of land animals, how effected, 73, 76
+ along mountain-chains, 81
+ of seeds by wind, 80, 257
+ by birds, 81, 258
+ by ocean-currents, 81, 258
+ of Azorean plants, facilities for, 260
+ Distribution, changes of, shown by extinct animals, 102
+ how to explain anomalies of, 420
+ Drontheim mountains, peculiar mosses of, 368
+ Dobson, Mr., on bats of Japan, 394
+ on the affinities of _Mystacina tuberculata_, 474
+ Dodo, the, 436
+ aborted wings of, 437
+ Dryiophidæ, 28
+ Dumeril, Professor, on lizards of Bourbon, 435
+ Duncan, Professor P. M., on ancient sea of central Australia, 496
+
+ E.
+ Early history of New Zealand, 484
+ Earth's age, 210
+ East Asian birds, range of, 38
+ East and West Australian floras, geological explanation of, 494
+ Echidna, 30
+ Echimyidæ, 27
+ Elevation of North America during glacial period, 154
+ causing diversion of gulf-stream, 154
+ Elwes, Mr. H. J., on distribution of Asiatic birds, 380
+ _Emberiza schoeniclus_, discontinuity of, 66
+ _E. passerina_, range of, 66
+ _E. pyrrhulina_, 66
+ Endemic genera of plants in Mauritius, &c., 443
+ Endemic genera of plants in New Zealand, 526
+ English plants in St. Helena, 297
+ Environment, change of, as modifying organisms, 225
+ _Eriocaulon septangulare_, 363
+ Ethiopian Region, definition of, 42
+ birds of, 43
+ Ettingshausen, Baron von, on the fossil flora of New Zealand, 499
+ on Australian plants in England, 518
+ Eucalyptus, wide range of, in Australia, 185
+ Eucalyptus and Acacia, why not in New Zealand, 507
+ Eucalyptus in Eocene of Sheppey, 518
+ Eupetes, distribution of, 25
+ Europe, Asia, &c., as zoological terms, 32
+ European birds, range of, 16
+ in Bermuda, 269
+ European occupation, effects of, in St. Helena, 294
+ European plants in New Zealand, 507
+ in Chile and Fuegia, 521
+ Everett, Mr., on Bornean birds, 377
+ on mammalia of the Philippines, 387
+ on Philippine birds, 388
+ on raised coral-reefs in the Philippines, 389
+ Evolution necessitates continuity, 70
+ Excentricity and precession, diagram of, 129
+ Excentricity, variations of, during three million years, 171
+ Excentricity a test of rival theories of climate, 171
+ Excentricity, high, its effects on warm and cold climates, 198
+ Explanation of peculiarities of the fauna of Celebes, 460
+ {554}
+ Extinct animals showing changes of distribution, 102
+ Extinct birds of the Mascarene Islands, 436
+ of New Zealand, 476
+ Extinction caused by glacial epoch, 122
+
+ F.
+ Families, restricted areas of, 29
+ distribution and antiquity of, 68
+ Fauna and flora, peculiarities of British, 370
+ Fauna of Borneo, affinities of, 381
+ of Java, 382
+ of Java and Asia compared, 384
+ Faunas of Hainan, Formosa, and Japan compared, 407
+ Felis, 17, 26
+ Ferns, abundance of, in Mascarene flora, 445
+ Ficus, fossil Arctic, 186
+ Fire-weed, the, of Tasmania, 513
+ Fisher, Rev. O., on temperature of space, 131
+ Fishes, dispersal of, 76
+ peculiar British, 340
+ cause of great speciality in, 343
+ mode of migration of fresh-water, 344
+ fresh-water, of New Zealand, 484
+ Floating islands, and the dispersal of animals, 74
+ Flora of the Azores, 256
+ of Bermuda, 271
+ of the Galapagos, 287
+ of St. Helena, 305
+ of the Sandwich Islands, 321;
+ peculiar features of, 323
+ peculiarities of the British, 360
+ of Madagascar and the Mascarene Islands, 439
+ of Madagascar and South Africa allied, 445
+ of New Zealand, 487
+ very poor, 488
+ its resemblance to the Australian, 489
+ its differences from the Australian, 490
+ origin of Australian element in, 498
+ tropical character of, explained, 500
+ summary and conclusion on, 506
+ Floras of New Zealand and Australia, summary of conclusion as to, 542
+ Florida and Canada, resemblances of, 5
+ and Bahamas, contrasts of, 5
+ Fogs cut off the sun's heat in glaciated countries, 145
+ Forbes, Mr. D., analysis of chalk, 91
+ Forbes, Mr. H. O., on plants of the Keeling Islands, 286
+ Formosa, 400
+ physical features of, 401
+ animal life of, 401
+ list of mammalia of, 402
+ list of land-birds peculiar to, 404
+ Forests, submerged, 335
+ Fowler, Rev. Canon, on peculiar British coleoptera, 346, 351
+ Freezing water liberates low-grade heat, 145
+ Fresh-water deposits, extent of, 97
+ organisms absent in St. Helena, 304
+ snail peculiar to Ireland, 356
+ fishes of the Seychelles, 433
+ Frogs of the Seychelles, 432
+ of New Zealand, 483
+ Fuegia, European plants in, 521
+ _Fulica alai_, 313
+
+ G.
+ Galapagos Islands, 275
+ Galapagos, absence of mammalia and amphibia from, 278
+ reptiles of, 278
+ birds of, 280
+ insects of, 284
+ land-shells of, 285
+ flora of, 287
+ and Azores contrasted, 290
+ _Galbula cyaneicollis_, distribution of, 18
+ _rufoviridis_, 18
+ _viridis_, 18
+ Galeopithecus, 63
+ _Gallinula sandvichensis_, 313
+ Gardner, Mr. J. S., on Tertiary changes of climate, 203
+ Garrulus, distribution of species of, 20
+ _Garrulus glandarius_, 21, 23, 65
+ _G. cervicalis_, 21
+ _G. krynicki_, 21
+ _G. atricapillus_, 21
+ _G. hyrcanus_, 21
+ _G. brandti_, 21, 23
+ _G. lanceolatus___, 22
+ _G. bispecularis_, 22
+ _G. sinensis_, 22
+ _G. taivanus_, 22
+ _G. japonicus_, 22, 65
+ Geikie, Dr. James, on interglacial deposits, 121
+ Sir Archibald, on age of buried river-channels, 337
+ on stratified rocks being found near shores, 87
+ on formation of chalk in shallow water, 96
+ on permanence of continents, 104
+ on variation in rate of denudation, 173
+ on the rate of denudation, 215
+ on small amount of marine denudation, 225
+ Genera, extent of, 17
+ origin of, 61
+ rise and decay of, 64
+ Generic areas, 17
+ Generic and Family distribution, 25
+ Genus, defined and illustrated, 17
+ Geographical change as a cause of glaciation, 148
+ changes, influence of, on climate, 150, 152
+ {555}
+ changes, effect of, on Arctic climates, 195
+ changes of Java and Borneo, 385
+ changes as modifying organisms, 228
+ Geological climates and geographical conditions, 204
+ time, 210
+ change, probably quicker in remote times, 223
+ time, value of the estimate of, 224
+ time, measurement of, 235
+ changes as aiding the migration of plants, 519
+ climates as affecting distribution, 534
+ climates, summary of causes of, 536
+ time, summary of views on, 539
+ Geology of Borneo, 375
+ of Madagascar, 412
+ of Celebes, 451
+ of New Zealand, 472
+ of Australia, 494
+ _Geomalacus maculcosus_, 356
+ Glacial climate not local, 113
+ deposits of Scotland, 112
+ Glacial epoch, proofs of, 107
+ effects of, on animal life, 117
+ alternations of climate during, 118
+ as causing migration and extinction, 122
+ causes of, 125
+ the essentials to the production of, 136
+ probable date of the, 160
+ and the climax of continental development, 206
+ date of last, 233
+ Glacial phenomena in North America, 116
+ Glaciation was greatest where rainfall is now greatest, 139
+ action of meteorological causes on, 142
+ summary of chief causes of, 144
+ in Northern Hemisphere, the only efficient cause of, 144
+ of New Zealand and South Africa, 162
+ local, due to high excentricity, 207
+ widespread in recent times, 536
+ Gleichenia in Greenland, 186
+ in relation to chalk, 89
+ Globigerina-ooze, analysis of, 91
+ Globigerinæ, where found, 92
+ Glyptostrobus, fossil, 186
+ Goats, destructiveness of, in St. Helena, 295
+ Godman, Mr., on birds reaching the Azores, 248, 250
+ Gray, Professor Asa, on extinction of European plants by the glacial
+ epoch, 123
+ Great Britain and Japan, birds common to, 396
+ Greene, Dr. J. Reay, on chameleons in Bourbon and Mauritius, 435
+ Greenland, loss of sun-heat by clouds in, 147
+ an anomaly in the Northern Hemisphere, 154
+ Miocene flora of, 183
+ Cretaceous flora of, 186
+ flora of ice-surrounded rocks of, 522
+ Grinnell Land, fossil flora of, 184
+ Guernsey, peculiar caddis-fly in, 355
+ Gulick, Rev. J. T., on Achatinellinæ, 318
+ Günther, Dr., on gigantic tortoises, 279
+ on peculiar British fishes, 341
+ on _Urotrichus gibsii_, 394
+ on lizards in the London Docks, 431
+ on Indian toads in Mauritius, 438
+ Guppy, Mr., on chalk of Solomon Islands, 91
+
+ H.
+ Haast, Dr., on otter-like mammal in New Zealand, 475
+ Habitability of globe due to disproportion of land and water, 209
+ _Haplothorax burchellii_, 299
+ Hartlaub, Dr., on "Lemuria," 423, 426
+ _Hatteria punctata_, 483
+ Haughton, Professor, on heat carried by ocean-currents, 194
+ comparison of Miocene and existing climates, 197
+ on geological time, 211, 219
+ on thickness of sedimentary rocks, 219
+ Hawaiian fauna and flora, antiquity of, 328
+ Heat and cold, how dispersed or stored up, 131
+ Heat required to melt snow, 134
+ evolved by frozen water, its nature and effects, 145
+ cut off by cloud and fogs, 145
+ Hector, Dr., on Triassic and Jurassic flora of New Zealand, 526
+ Heer, Professor, on chalk sea in Central Europe, 93
+ Heilprin, Professor, on insects of Bermuda, 269
+ on land-shells of Bermuda, 270
+ _Helianthemum Breweri_, 360, 363
+ Heliodus, an American fossil, 69
+ Helix, 17
+ Hemiptera of St. Helena, 303
+ Hepaticæ, peculiar British, 366
+ non-European genera of, in Britain, 367
+ Hesperomys, 26
+ Hesperornis allied to ostriches, 481
+ _Hieracium iricum_, 362
+ High land essential to the production of a glacial epoch, 195
+ Hildebrand, Dr. W., on flora of the Sandwich Islands, 321
+ Himalayan birds and insects in Celebes, 462
+ Hippopotamus in Yorkshire as proving a mild climate, 119
+ Hochstetter on the aquatic mammal of New Zealand, 475
+ {556}
+ Hooker, Sir Joseph, on the Galapagos flora, 287
+ on affinities of St. Helena plants, 306
+ on peculiar British plants, 360, 363
+ on the flora of New Zealand, 488
+ on proportion of temperate and tropical Australian floras, 492
+ on current of vegetation from north to south, 510
+ on supposed occurrence of Australian plants in England in the Tertiary
+ period, 518
+ Horne, Mr. John, on ice-sheet covering the Isle of Man, 115
+ Hull, Professor, on Permian breccias in Ireland indicating ice-action,
+ 201
+ Humming-birds, restricted ranges of, 16
+ Hutton, Captain, on struthious birds of New Zealand, 479
+ Huxley, Professor, on geological time, 211
+ on European origin of African animals, 419
+ Hyomoschus, 27
+ Hyracoidea, restricted range of, 30
+
+ I.
+ Ice-action, what evidences of, during the Tertiary period, 178
+ indications of ancient, 200
+ Ice-borne rocks, a test of a glacial epoch, 176
+ in Miocene of N. Italy, 178
+ in Eocene of Alps, 178
+ in Eocene of Carpathians and Apennines, 179
+ absence of, in English and N. American Tertiaries, 180
+ Ice-cap, why improbable or impossible, 161
+ Iceland, a continental island, 450
+ Icteridæ, 50
+ Iguanidæ, 50
+ Indian birds in Formosa, 407
+ Indian Ocean as a source of heat in Tertiary times, 192
+ Indian genera of plants in Australia, 492
+ Indicator, distribution of, 25
+ Insectivora in Madagascar, 417
+ Insects, dispersal of, 77
+ of the Miocene period, 77
+ restriction of range of, 78
+ of the Azores, 253
+ of Bermuda, 269
+ of the Galapagos, 284
+ of St. Helena, 298
+ of the Sandwich Islands, 318
+ peculiar British, 344
+ of Celebes, peculiarities of, 462
+ scarcity of, in New Zealand, 505
+ Insular faunas, summary of conclusions as to, 539, 542
+ Interglacial warm periods on the continent and in North America, 121
+ Interglacial periods and their probable character, 152
+ Interglacial periods will not occur during an epoch of extreme
+ glaciation, 155
+ Interglacial climates never very warm, 159
+ Ireland, poverty of, in reptiles, 339
+ in plants, 339
+ peculiar fishes of, 342
+ plants of, not found in Great Britain, 364
+ Islands, classification of, 242
+ importance of, in study of distribution, 241
+ remote, how stocked with plants and animals, 261
+ submerged between Madagascar and India, 425
+ Isle of Wight, peculiar beetle of, 351
+ _Isatis tinctoria_, on railway bank, 513
+ Ithaginis, 26
+
+ J.
+ Japan, zoological features of, 393
+ mammalia of, 394
+ birds of, 396
+ birds peculiar to, 398
+ birds in distant areas, 399
+ Japan and Formosa, 391
+ Java, fauna of, 382
+ Asiatic species in, 384
+ Java and Borneo, past changes of, 385
+ Jays, distribution of species of, 20
+ of Europe and Japan, 67
+ Jeffreys, Dr. Gwyn, on shallow-water mollusca in chalk, 92
+ on fossil shallow-water shells in deep water, 337
+ Jones, Mr., on migration of birds to Bermuda, 268
+ on vegetation of the Bermudas, 272
+ Juan Fernandez, flora and fauna of, 287
+ Judd, Prof. J. W., on absence of glaciation in east Europe, 139
+ on glaciation of the Alps produced by elevation, 179
+ _Juniperus barbadensis_, 272
+ Jura, travelled blocks on, 110
+ Jurassic warm Arctic climate, 202
+
+ K.
+ Keeling Islands, animals of, 286
+ Kirk, Mr. T., on temporary introduced plants, 515
+ Knowledge of various kinds required for study of geographical
+ distribution, 7, 9
+
+ L.
+ _Lagopus scoticus_, 340
+ Land as a barrier to ocean-currents, 150
+ {557}
+ Land and sea, changes of, 83
+ how changes of, affect climate, 148, 150
+ Land and water, disproportion of, renders globe habitable, 209
+ Land-birds of Celebes, list of, 466
+ Land-connection, how far necessary to dispersal of mammals, 73
+ Land-shells, great antiquity of, 79
+ universal distribution of, 79
+ causes favouring the abundance of, 79
+ of the Azores, 256
+ of Bermuda, 270
+ of the Galapagos, 284
+ of St. Helena, 304
+ of the Sandwich Islands, 316
+ of the Seychelles, 434
+ _Laurus canariensis_, 260
+ Leguat on animals of Bourbon, 435
+ on the Solitaire, 436
+ Leguminosæ, abundance of, in Australia, 490
+ "Lemuria," a supposed submerged continent, 422-426
+ Lemurs in Madagascar, 416
+ Lendenfeld, Dr. R. von, on glaciation in the Australian Alps, 163
+ Leopard, enormous range of, 14
+ Lepidoptera, list of peculiar British, 347
+ Lepidosiren, 63
+ _Lepidosiren paradoxa_ and _L. annectens_, 69
+ Lepidosternidæ, 27
+ Limestone as indicating change of sea and land, 84
+ _Limnæa involuta_, 356
+ _Linaria purpurea_, on railway bank, 514
+ _Liopelma hochstetteri_, in New Zealand, 483
+ Liotrichidæ, 29
+ List of the land-birds of Celebes, 466
+ Lizard peculiar to the Mascarene Islands, 438
+ Lizards of the Galapagos, 278
+ local variation of colour of, 431
+ of New Zealand, 483
+ Lobeliaceæ, abundance of, in the Sandwich Islands, 324
+ Locality of a species, importance of, 12
+ _Loddigesia mirabilis_, rarity of, 16
+ Lord, Mr., on species of Urotrichus, 394
+ Low-grade and high-grade heat, 145
+ Lowlands nowhere covered with perpetual snow, 136
+ Lundy Island, peculiar beetles of, 354
+ Lyell, Sir Charles, on permanence of continents, 84
+ on calcareous mud, 90
+ on the distribution of chalk, 93
+ on geographical causes as modifying climate, 148
+ on estimate of geological time, 211, 235
+ on classification of sedimentary rocks, 217
+ Lynxes, a Palæarctic group, 41
+
+ M.
+ McLachlan, Mr., on peculiar British caddis-flies, 355
+ Madagascar, physical features of, 412
+ former condition of, 414
+ biological features of, 416
+ mammalia of, 416
+ reptiles of, 417
+ relation of, to Africa, 418
+ early history of, 419
+ birds of, in relation to "Lemuria," 422
+ flora of, 439
+ conclusion on fauna and flora of, 446
+ great antiquity of, 446
+ Madagascar and Africa, contrast of, 6
+ Maillard on animals of Bourbon, 435
+ Malay Islands, local peculiarities of flora in, 187
+ past history of, 389
+ Malayan birds in Formosa, 406
+ Mammalia of East Asia, range of, 34
+ of North Africa, range of, 34
+ Mammalia, dispersal of, 73
+ of Britain, range of, 33
+ poverty of, 329
+ of Borneo, 376
+ of Java, 382
+ of the Philippines, 387
+ of Japan, 393
+ of Formosa, 402
+ common to Formosa and India, 403
+ of Madagascar, 416
+ of Comoro Islands, 428
+ of Celebes, 455; whence derived, 457
+ of New Zealand, 474
+ Maori legend of origin of the forest-rat, 475
+ Maoris, their accounts of the moa, 477
+ Map of the old Rhone glacier, 110
+ of North and South Polar Regions, 138
+ of the Azores, 248
+ of Bermuda, 263
+ of the Galapagos, 276, 277
+ of the South Atlantic Ocean, 293
+ of the Sandwich Islands, 311
+ of the North Pacific with its submerged banks, 312
+ of British Isles and the 100-fathom bank, 333
+ of Borneo and Java, 374
+ of Japan and Formosa, 392
+ physical, of Madagascar, 413
+ of the Madagascar group, 415
+ of the Indian Ocean, 425
+ of Celebes, 452
+ of sea-bottom around New Zealand, 472
+ of Australia in Cretaceous period, 497
+ Marcou, Professor Jules, on the Pliocene and glacial epochs, 233
+ Marmot, range of, 15
+ Mars as illustrating glacial theories, 164, 168
+ {558}
+ Mars, no true ice-cap on, 166
+ Marsupials, range of, 30
+ Marsh, Prof. O. C., on the Atlantosaurus, 98
+ on Hesperornis, 481
+ Marsh, Mr., on camels as desert-makers, 296
+ Mascarene Islands, 428-445
+ Mascarene plants, curious relations of, 442
+ endemic genera of, 443
+ Mascarene flora, fragmentary character of, 444
+ abundance of ferns in, 445
+ Mauritius, Bourbon, and Rodriguez, 434
+ Measurements of geological time, 233
+ agreement of various estimates of, 235
+ concluding remarks on, 236
+ _Medicago sativa_ in New Zealand, 515
+ Megalæmidæ, 27
+ Meleagris, 50
+ _Melilotus vulgaris_, on railway banks, 513
+ Meliphagidæ, 47
+ Melliss, Mr., on the early history of St. Helena, 295
+ _Melospiza melodia_, variation of, 58
+ Merycotherium, 123
+ Meteorological causes as intensifying glaciation, 142
+ Migration caused by glacial epoch, 122
+ of birds to Bermuda, 267
+ of plants from north to south, 512
+ of plants and alterations of snow line, 516
+ of plants due to changes of climate, 517
+ of plants from north to south, long continued, 518
+ of plants aided by geological changes, 519
+ of plants by way of the Andes, 520
+ of plants by way of Himalayas and South Asia, 523
+ of plants through Africa, 524
+ Mild Arctic climates, stratigraphical evidence of, 187
+ causes of, 190
+ dependent on geographical changes, 191
+ effects of high excentricity on, 198
+ summary of causes of, 537
+ Miocene Arctic flora, 183
+ flora of Europe, 123
+ or Eocene floras, 185
+ deposits of Java, 385
+ fauna of Europe and North India, 419
+ Mississippi, matter carried away by, 172
+ Mitten, Mr. William, on peculiar British mosses and hepaticæ, 365, 368
+ on temporary appearance of plants, 513
+ Mniotiltidæ, a nearctic group, 49
+ Mnium, peculiar species of, in the Drontheim mountains, 368
+ Moas of New Zealand, 476
+ Mollusca, dispersal of, 78
+ Monotremata, restricted range of, 30
+ Moraines, 108
+ of Ivrea, 116
+ More, Mr. A. G., on peculiar Irish plants, 364
+ Morgan, Mr. C. Lloyd, on thickness of formations not affected by
+ denudation, 220
+ Moseley, Mr. H. N., on seeds carried by birds, 259
+ on the flora of Bermuda, 272
+ Mosses, peculiar British, 366
+ non-European genera of, in Britain, 367
+ how diffused and why restricted, 368
+ Mt. St. Elias, why not ice-clad, 154
+ Mountain chains aiding the dispersal of plants, 81
+ as aids to migration of plants, 513
+ Mueller, Baron von, census of Australian plants, 492
+ _Munia brunneiceps_, in Celebes, 463
+ Murray, Mr. J., on oceanic deposits, 86
+ on chalk-like globigerina-ooze, 92
+ on mean height of continents, 216
+ on land-area of the globe, 221
+ Mus, 17, 26
+ _Mygale pyrenaica_, range of, 15, 24
+ _M. muscovitica_, 24
+ _Myialestes helianthea_ in Celebes, 463
+ _Myrica faya_, 260
+ Myrsine, fossil in Greenland, 186
+ _Mytilus edulis_, sub-fossil in Spitzbergen, 182
+
+ N.
+ Nares, Capt. Sir G., on snow and ice in high latitudes, 135
+ on abrupt elevation of Bermuda, 264
+ Nearctic Region, definition of, 48
+ mammalia of, 48
+ birds of, 49
+ reptiles of, 50
+ _Nectarinea osea_, restricted range of, 16
+ Neilgherries, Australian plants naturalized in, 528
+ Neotropical Region, definition of, 51
+ low types of, 52
+ Nevill, Mr. Geoffrey, on land-shells of the Seychelles, 434
+ on destruction of Seychelles flora, 445
+ New species, origin of, 56
+ Newton, Mr. E., on short wings of the Seychelles dove, 437
+ Newton, Professor, on recently extinct birds, 437
+ Newts, restricted range of, 30
+ New Zealand, recent glaciation of, 163
+ New Zealand, 471
+ geology of, 472
+ form of sea-bottom around, 473
+ zoological character of, 473
+ mammalia of, 474
+ {559}
+ wingless birds of, 476
+ past changes of, 478
+ winged birds and lower vertebrates of, 482
+ deductions from peculiarities of fauna of, 484
+ period of its union with N. Australia, 484
+ the flora of, 487, 506
+ origin of Australian element in the flora of, 498
+ tropical character of flora, 500
+ tropical genera common to Australia, 501
+ temperate species common to Australia, 502
+ route of Arctic plants to, 521
+ European plants in, 509
+ endemic genera of plants in, 526
+ great antiquity of, 526
+ Nordenskjöld, Prof., on absence of perpetual snow in N. Asia, 135
+ on recent milder climate in Spitzbergen, 182
+ on former Polar climates, 187
+ on geology of Spitzbergen, 188
+ North America, glacial phenomena in, 116
+ interglacial warm periods in, 121
+ condition of, in Tertiary period, 194
+ Northern genera of plants in S. temperate America, 521
+ hemisphere, absence of southern plants from, 527
+ flora, hardiness of, 528
+
+ O.
+ Ocean-currents as carriers of plants, 81
+ as affecting interglacial periods, 152
+ as determining climate, 153
+ effects of, in Tertiary times, 196
+ Ocean, Darwin on permanence of, 100
+ Oceanic and continental islands, 242
+ Oceanic islands a proof of the permanence of oceans, 100
+ Oceanic islands, 244
+ --the Azores, 247
+ general remarks on, 329
+ Octodontidæ, 27
+ _Oenanthe fluviatilis_, 361
+ Oeninghen, Miocene flora of, 183
+ _Oenothera odorata_, on a railway bank, 514
+ Oliver, Professor, on peculiar Bermudan plants, 272
+ Operculata, scarcity of, in the Sandwich Islands, 317
+ _Ophrys apifera_, temporary appearance of, 514
+ Orchideæ, species have restricted ranges, 505
+ Orchids, abundance of, in Bourbon and Mauritius, 446
+ why almost universal in the tropics, 446
+ Orders, distribution of, 30
+ Organic change dependent on change of conditions, 225, 228
+ Oriental Region, definition of, 44
+ mammals and birds of, 44
+ reptiles of, 45
+ insects of, 45
+ Origin of new species, 56, 60
+ of new genera, 61
+ of the Galapagos flora, 288
+ of the beetles of St. Helena, 298
+ of Australian element in the New Zealand flora, 498
+ Orkney, peculiar fishes of, 341
+ Orthonyx not a New Zealand genus, 483
+ Osprey, wide range of, 15
+ Ostriches, limitation of, 30
+ Otter-like mammal in New Zealand, 475
+ Overlapping and discontinuous areas, 28
+
+ P.
+ _Pachyglossa aureolimbata_, in Celebes, 463
+ Palæarctic Region, limits of, 39
+ characteristic features of, 41
+ Palæozoic formations, depth of, round London, 218
+ Palm confined to Round Island, 444
+ Panax, fossil in Greenland, 186
+ Papilio, 17
+ Paraguay, no wild horses or cattle in, 226
+ Parnassius, Palæarctic, 42
+ _Parus ater_, 19
+ _P. borealis_, 19, 64
+ _P. britannicus_, 321
+ _P. camtschatkensis_, 19
+ _P. cinctus_, 20
+ _P. coeruleus_, 20
+ _P. cyaneus_, 20
+ _P. cristatus_, 20
+ _P. ledouci_, 20
+ _P. lugubris_, 20
+ _P. major_, 19
+ _P. palustris_, 19; discontinuous area of, 65
+ _P. rosea_, 340
+ _P. teneriffæ_, 20
+ Passeres of the Sandwich Islands, 314
+ Past changes of New Zealand, 478
+ Payer, Lieut., on evaporation of ice during the Arctic summer, 140
+ Peculiar fauna of New Zealand, deductions from, 484
+ Pengelly, Mr., on submerged forests, 335
+ _Pennula millei_, in Sandwich Islands, 313
+ Permanence of continents, summary of evidence for, 103
+ Permian formation, indications of ice-action in, 200
+ Perodicticus, a local genus, 26
+ _Petroselinum segetum_, on railway bank, 514
+ {560}
+ Philippine Islands, 387
+ mammalia of, 387
+ birds of, 388
+ past history of, 389
+ _Phyllodactylus galapagensis_, 279
+ _Phylloscopus borealis_, range of, 15
+ Physical causes which determine distribution, 533
+ features of Formosa, 401
+ Pica, 17
+ Pickering, Dr., on the flora of the Sandwich Islands, 323
+ on temperate forms on mountains of the Sandwich Islands, 323
+ _Pithecia monachus_, distribution of, 18
+ _P. rufibarbata_, 18
+ Pitta, distribution of, 25
+ Plants, dispersal of, 80
+ seeds of, adapted for dispersal, 80
+ wide range of species and genera of, 185
+ poverty of, in Ireland, 339
+ peculiar British, 359
+ of Ireland not in Great Britain, 364
+ cause of their wide diffusion and narrow restriction, 369
+ easily dispersed often have restricted ranges, 504
+ how they migrate from north to south, 512
+ of existing genera throughout the Tertiary period, 520
+ southern migration of, by way of the Himalayas, 523
+ southern migration of, through Africa, 524
+ endemic genera of, in New Zealand, 526
+ Platypus, 30
+ _Plestiodon longirostris_ of Bermuda, 266
+ Po, matter carried away by, 173
+ Podargus, Australian genus, 47
+ Poecilozonites, peculiar to Bermuda, 270
+ _Poinciana regia_ in Madagascar, 440
+ Populus, fossil in Spitzbergen, 184
+ Pourtales, Count, on modern formation of chalk, 95
+ on sedimentary deposits in Gulf of Mexico, 222
+ Poverty in species of Britain, 338
+ Precession of Equinoxes, influence of, on climate, 126
+ Preservation of species, 63
+ Proboscidea, range of, 30
+ Proteus, why preserved, 63
+ Psophia, range of species of, 18
+ Pteroptochidæ, 29
+ Pyrenean ibex, restricted range of, 15
+
+ R.
+ Railways, new plants on, 513
+ Ramsay, Mr. Wardlaw, on Philippine birds, 388
+ Professor, on ancient land surfaces, 99
+ on geological time 212
+ on thickness of sedimentary rocks, 219
+ Rat, native, of New Zealand, 475
+ Rate of organic change usually measured by an incorrect scale, 232
+ Rats in the Galapagos, 278
+ Raven, wide range of, 15
+ Reade, T. Mellard, on changes of sea and land, 84
+ Recent continental islands, 243, 331
+ Red clay of Bermuda, 265
+ Reptiles, dispersal of, 75
+ of the Galapagos, 278
+ of the Sandwich Islands, 316
+ cause of scarcity of, in British Isles, 339
+ of Madagascar, 417
+ of the Seychelles, 430
+ of Mauritius and Round Island, 438
+ of New Zealand, 483
+ _Rhodolæna altivola_ in Madagascar, 440
+ _Rhus toxicodendron_ in Bermuda, 272
+ Ridgway, Mr., on birds of Galapagos, 281
+ River-channels, buried, 336
+ _Roches moutonnées_, 108
+ Rodents in Madagascar, 417
+ Round Island, a snake and a palm peculiar to, 438, 444
+ _Rumex pulcher_ in New Zealand, 515
+ Rye, Mr. E. C., on peculiar British insects, 345, 351
+
+ S.
+ St. Helena, 292
+ effects of European occupation on the vegetation of, 294
+ insects of, 298
+ land-shells of, 304
+ absence of fresh-water organisms in, 304
+ native vegetation of, 305
+ Salvin, Mr., on the birds of the Galapagos, 280
+ Sandwich Islands, the, 310
+ zoology of, 313
+ birds of, 313
+ reptiles of, 316
+ land-shells of, 316
+ insects of, 318
+ vegetation of, 321
+ antiquity of fauna and flora of, 328
+ Sassafras, in Swiss Miocene, 183
+ Scandinavian flora, aggressive power of, 511
+ Scientific voyages, comparative results of, 7
+ Sciurus, 26
+ Sclater, Mr. P. L., on zoological region, 32, 39
+ Scotland, glacial deposits of, 112-115
+ probable rate of denudation in, 173
+ Miocene flora of, 184
+ peculiar fishes of, 341
+ {561}
+ _Scotophilus tuberculatus_ in New Zealand, 474
+ Scrophularincæ, why few species are common to Australia and New Zealand,
+ 505
+ Sea, depth of, around Madagascar, 414
+ depth of, around Celebes, 452
+ Sea-bottom around New Zealand and Australia, 473
+ Sea-level, changes of, dependent on glaciation, 161
+ complex effects of glaciation on, 162, 164
+ rise of, a cause of denudation, 174
+ Seas, inland, in Tertiary period, 191
+ Section of sea-bottom near Bermuda, 264
+ Sedges and grasses common to Australia and New Zealand, 504
+ Sedimentary rocks, how to estimate thickness of, 217
+ thinning out of, 217
+ how formed, 218
+ thickness of, 217, 221
+ summary of conclusions on the rate of formation of the, 221
+ Seebohm, Mr., on _Parus palustris_, 65
+ on _Emberiza schoeniclus_, 66
+ on snow in Siberia, 166
+ on birds of Japan, 396
+ Seeds, dispersal of, 257
+ carried by birds, 258
+ _Senecio australis_, on burnt ground, 513
+ Sericinus, Palæarctic, 42
+ Seychelles Archipelago, 429
+ birds of, 430
+ reptiles and amphibia of, 430
+ fresh-water fishes of, 433
+ land-shells of, 434
+ Sharp, Dr. D., on beetles of the Sandwich Islands, 319
+ on peculiar British beetles, 345
+ Shells, peculiar to Britain, 356
+ Shetland Isles, peculiar beetle of, 354
+ Shore deposits, 85, 211
+ proving the permanence of continents, 97
+ distance from coast of, 221
+ _Sialia sialis_, variation of, 58
+ Siberia, amount of snow and its sudden disappearance in, 166
+ Silurian boulder-beds, 201
+ warm Arctic climate, 202
+ Simiidae, 27
+ _Sisyrinchium bermudianum_, 272
+ Skertchley, Mr., on four distinct boulder-clays, 118
+ on Tertiary deposits in Egypt and Nubia, 191
+ on climatic stability of present epoch, 233
+ Slug peculiar to Ireland, 356
+ Snake peculiar to Round Island, 438
+ Snakes of the Galapagos, 280
+ of the Seychelles, 431
+ Snow and ice, properties of, in relation to climate, 131
+ Snow, effects of, on climate, 133
+ Snow, quantity of heat required to melt, 134
+ often of small amount in high latitudes, 135
+ never perpetual on lowlands, 136
+ conditions determining perpetual, 137
+ maintains cold by reflecting the solar heat, 144
+ Snow-line, alterations of, causing migration of plants, 516
+ Sollas, Mr. J. W., on greater intensity of telluric action in past time,
+ 223
+ South Africa, recent glaciation of, 163
+ many northern genera of plants in, 524
+ its supposed connection with Australia, 525
+ South American plants in New Zealand, 521
+ South Temperate America, poor in species, 53
+ climate of, 146
+ Southern flora, comparative tenderness of, 528
+ Southern plants, why absent in the Northern Hemisphere, 527
+ Space, temperature of, 129
+ Specialisation antagonistic to diffusion of _species_, 505
+ Species, origin of new, 56
+ extinction of, 63
+ rise and decay of, 64
+ epoch of exceptional stability of, 232
+ dying out and replacement of, 409
+ preservation of, in islands, 410
+ Specific areas, 14; discontinuous, 64
+ _Spiranthes romanzoviana_, 364
+ Spitzbergen, Miocene flora of, 184
+ absence of boulder-beds in, 187
+ Spruce, Dr. Richard, on the dispersion of hepaticæ, 309
+ Stability of extreme glacial conditions, 159
+ Stainton, Mr. H. T., on peculiar British moths, 346-350
+ Stanivoi mountains, why not ice-clad, 154
+ Starlings, genera of, in New Zealand, 482
+ _Stellaria media_, temporary appearance of, 515
+ Sternum, process of abortion of keel of, 437
+ Stow, Mr. G. W., on glacial phenomena in South Africa, 163
+ Stratified rocks formed near shores, 85, 87
+ deposits, how formed, 218
+ Striated rocks, 107
+ blocks in the Permian formation, 200
+ _Striæ flammea_, range of, 15
+ Struthiones, 30
+ Struthious birds of New Zealand as indicating past changes, 478
+ Stylidium, wide range of, 185
+ Submerged forests, 334
+ {562}
+ Subsidence of isthmus of Panama, 151
+ Sumatra, geology of, 385
+ Sweden, two deposits of "till" in, 121
+ Swimming powers of mammalia, 74
+ Swinhoe, Mr. Robert, researches in Formosa, 400
+ Switzerland, interglacial warm periods in, 121
+ Sylviadæ, overlapping genera of, 29
+
+ T.
+ Talpidæ, a Palæarctic group, 41
+ Tapirs, distribution of, 25
+ former wide range of, 393
+ Tarsius, 63
+ _Tarsius spectrum_ in Celebes, 456
+ Tasmania and North Australia, resemblance of, 5
+ route of Arctic plants to, 520
+ _Taxodium distichum_ in Spitzbergen, 184
+ Temperate climates in Arctic regions, 181
+ Australian genera of plants in New Zealand, 502
+ Australian species of plants in New Zealand, 502
+ Temperature, how dependent on sun's distance, 129
+ of space, 129
+ Tertiary glacial epochs, evidence against, 179
+ warm climates, continuous, 187
+ Test of glaciation at any period, 175
+ _Testudo abingdonii_, 279
+ _T. microphyes_, 278
+ Tetraogallus, distribution of, 24
+ Thais, a Palæarctic genus, 42
+ Thomson, Sir William, on age of the earth, 213
+ Sir Wyville, on organisms in the globigerina-ooze, 89
+ analysis of globigerina-ooze, 91
+ _Thryothorus bewickii_, discontinuity of, 68
+ "Till" of Scotland, 112
+ several distinct formations of, 121
+ Tits, distribution of species of, 19
+ Torreya, fossil in Spitzbergen, 186
+ Tortoises of the Galapagos, 278
+ Trade-winds, how modified by a glacial epoch, 142
+ Tragulidæ, 27
+ Travelled blocks, 109
+ Tremarctos, an isolated genus, 29
+ Triassic warm Arctic climate, 200
+ Tribonyx not a New Zealand genus, 483
+ Trichoptera peculiar to Britain, 355
+ Trogons, distribution of, 28
+ Tropical affinities of New Zealand birds, 483
+ character of the New Zealand flora, cause of, 500
+ genera common to New Zealand and Australia, 501
+ Turdus, 17, 26
+ _Turdus fuscescens_, variation of, 58, 59
+ Tylor, A., on estimating the rate of denudation, 214
+ Tyrannidæ, an American family, 50
+
+ U.
+ Uraniidæ, 28
+ Uropeltidæ, 30
+ Urotrichus, distribution of, 25
+ Ursus, 26
+
+ V.
+ Variation in animals, 57
+ amount of, in N. American birds, 58
+ Vegetation, local peculiarities of, 185
+ effects of Polar night on, 198
+ _Vesperugo serotinus_, range of, 14
+ _Vireo bellii_, supposed discontinuity of, 68
+ Vireonidæ, an American family, 49
+
+ W.
+ Wallich, Dr., on habitat of globigerinæ, 92
+ Warren, Mr. W., information on British lepidoptera, 347
+ Water, properties of, in relation to climate, 131, 133
+ Waterhouse, Mr., on Galapagos beetles, 284
+ Wales, peculiar fish of, 341
+ Warm climates of northern latitudes, long persistence of, 201
+ Watson, Mr. H. C., on the flora of the Azores, 256
+ on peculiar British plants, 359
+ on vegetation of railway banks, 513
+ Webb, Mr., on comparison of Mars and the Earth, 166
+ West Australia, rich flora of, 494
+ former extent and isolation of, 497
+ West Indies, a Neotropical district, 53
+ White, Dr. F. Buchanan, on the Hemiptera of St. Helena, 303
+ Mr. John, on native accounts of the moa, 477
+ Whitehead, Mr. John, on Bornean birds, 377
+ Wilson, Mr. Scott B., on birds of the Sandwich Islands, 314
+ Winged birds of New Zealand, 482
+ Wingless birds never inhabit continents, 437
+ their evidence against "Lemuria," 438
+ of New Zealand, 476
+ Wings of struthious birds show retrograde development, 437
+ {563}
+ Winter temperature of Europe and America, 196
+ Wolf, range of, 14
+ Wollaston, Mr. T. V., on insular character of St. Helena, 294
+ on St. Helena shells and insects, 297
+ Wood, Mr. Searles V., jun., on formation of "till," 114
+ on alternations of climate, 118
+ on causes of glacial epochs, 125
+ conclusive objection to the excentricity theory, 160
+ on continuous warm Tertiary climates, 180
+ Woodward, Dr. S. P., on Ammonites living in shallow water, 95
+ Woodward, Mr., on "Lemuria," 426
+ Wright, Dr. Percival, on lizards of the Seychelles, 431
+
+ Y.
+ Young, Professor J., on contemporaneous formation of deposits, 221
+ Young Island, lofty Antarctic, 522
+
+ Z.
+ Zoology of the Azores, 248
+ of Bermuda, 262
+ of the Sandwich Islands, 313
+ of Borneo, 376
+ of Madagascar, 416
+ of islands round Celebes, 453
+ of Celebes, 455
+ Zoological and geographical regions compared, 32, 54
+ Zoological features of Japan, 393
+ character of New Zealand, 473
+
+THE END
+
+{564}
+
+RICHARD CLAY AND SONS, LIMITED,
+LONDON AND BUNGAY.
+
+ * * * * *
+
+
+[1] A small number of species belonging to the West Indies are found in the
+extreme southern portion of the Florida Peninsula.
+
+[2] I cannot avoid here referring to the enormous waste of labour and money
+with comparatively scanty and unimportant results to natural history of
+most of the great scientific voyages of the various civilized governments
+during the present century. All these expeditions combined have done far
+less than private collectors in making known the products of remote lands
+and islands. They have brought home fragmentary collections, made in widely
+scattered localities, and these have been usually described in huge folios
+or quartos, whose value is often in inverse proportion to their bulk and
+cost. The same species have been collected again and again, often described
+several times over under new names, and not unfrequently stated to be from
+places they never inhabited. The result of this wretched system is that the
+productions of some of the most frequently visited and most interesting
+islands on the globe are still very imperfectly known, while their native
+plants and animals are being yearly exterminated, and this is the case even
+with countries under the rule or protection of European governments. Such
+are the Sandwich Islands, Tahiti, the Marquesas, the Philippine Islands,
+and a host of smaller ones; while Bourbon and Mauritius, St. Helena, and
+several others, have only been adequately explored after an important
+portion of their productions has been destroyed by cultivation or the
+reckless introduction of goats and pigs. The employment in each of our
+possessions, and those of other European powers, of a resident naturalist
+at a very small annual expense, would have done more for the advancement of
+knowledge in this direction than all the expensive expeditions that have
+again and again circumnavigated the globe.
+
+[3] The general facts of Palæontology, as bearing on the migrations of
+animal groups, are summarised in my _Geographical Distribution of Animals_,
+Vol. I. Chapters VI., VII., and VIII.
+
+[4] Since these lines were written, a fine series of specimens of this rare
+humming-bird has been obtained from the same locality. (See _Proc. Zool.
+Soc._ 1881, pp. 827-834.)
+
+[5] Many of these large genera are now subdivided, the divisions being
+sometimes termed genera, sometimes sub-genera.
+
+[6] The Palæarctic region includes temperate Asia and Europe, as will be
+explained in the next chapter.
+
+[7] The following list of the genera of reptiles and amphibia peculiar to
+the Palæarctic Region has been furnished me by Mr. G. A. Boulenger, of the
+British Museum:--
+
+ SNAKES. FROGS AND TOADS.
+
+ _Achalinus_--China, Japan. _Pelobates_--Eur., S.W. Asia.
+ _Coelopeltis_--S. Eur., N. Af., _Pelodytes_--W. Europe.
+ S.W. Asia. _Discoglossus_--S. Eur., N.W. Af.
+ _Macroprotodon_--S. Eur., N. Af. _Bombinator_--Eur., Temp. Asia.
+ _Taphrometopon_--Cent. Asia. _Alytus_--Cent. and W. Eur.
+
+ LIZARDS. NEWTS.
+
+ _Phrynocephalus_--Cent. and S.W. _Salamandra_--Eur., N. Af., S.W.
+ Asia. Asia.
+ _Anguis_--Europe, W. Asia. _Chioglossa_--Spain and Portugal.
+ _Blanus_--S.W. Eur., N.W. Africa, _Salamandrina_--Italy.
+ S.W. Asia. _Pachytriton_--East Thibet.
+ _Trogonophis_--N.W. Africa. _Hynobius_--China and Japan.
+ _Lacerta_--Eur., Temp. Asia, N. _Geomolge_--E. Manchuria.
+ Africa (one sp. in _Onychodactylus_--Japan.
+ W. Af.). _Salamandrella_--Siberia.
+ _Psammodromus_--S.W. Eur., N.W. _Ranidens_--Siberia.
+ Africa. _Batrachyperus_--East Thibet.
+ _Algiroides_--S. Eur. _Myalobatrachus_--China, Japan.
+ _Proteus_--Caverns of S. Austria.
+
+[8] Remains of the dingo have been found fossil in Pleistocene deposits but
+the antiquity of man in Australia is not known. It is not, however,
+improbable that it may be as great as in Europe. My friend A. C. Swinton,
+Esq., while working in the then almost unknown gold-field of Maryborough,
+Victoria, in January, 1855, found a fragment of a well-formed stone axe
+resting on the metamorphic schistose bed-rock about five feet beneath the
+surface. It was overlain by the compact gravel drift called by the miners
+"cement," and by an included layer of hard iron-stained sandstone. The
+fragment is about an inch and three-eighths wide and the same length, and
+is of very hard fine-grained black basalt. One side is ground to a very
+smooth and regular surface, terminating in a well-formed cutting edge more
+than an inch long, the return face of the cutting part being about a
+quarter of an inch wide. The other side is a broken surface. The weapon
+appears to have been an axe or tomahawk closely resembling that figured at
+p. 335 of Lumholtz's _Among Cannibals_, from Central Queensland. The
+fragment was discovered by Mr. Swinton and the late Mr. Mackworth Shore,
+one of the discoverers of the gold-field, before any rush to it had taken
+place, and it seems impossible to avoid the conclusion that it was formed
+prior to the deposit of the gravel drift and iron-stained sandstone under
+which it lay. This would indicate a great antiquity of man in Australia,
+and would enable us to account for the fossilised remains of the dingo in
+Pleistocene deposits as those of an animal introduced by man.
+
+[9] These facts are taken from a memoir on _The Mammals and Winter Birds of
+Florida_, by J. A. Allen; forming Vol. II., No. 3, of the Bulletin of the
+Museum of Comparative Zoology at Harvard College, Cambridge, Massachusetts.
+
+[10] The great variation in wild animals is more fully discussed and
+illustrated in the author's _Darwinism_ (Chapter III.).
+
+[11] See _Ibis_, 1879, p. 32.
+
+[12] In Mr. Seebohm's latest work, _Birds of the Japanese Empire_ (1890),
+he says, "Examples from North China are indistinguishable from those
+obtained in Greece" (p. 82).
+
+[13] _Ibis_, 1879, p. 40. In his _Birds of the Japanese Empire_ (1890), Mr.
+Seebohm classes the Japanese and European forms as _E. schoeniclus_, and
+thinks that their range is probably continuous across the two continents.
+
+[14] Lyell's _Principles of Geology_, ii., p. 369.
+
+[15] Mr. Darwin found that the large _Helix pomatia_ lived after immersion
+in sea-water for twenty days. It is hardly likely that this is the extreme
+limit of their powers of endurance, but even this would allow of their
+being floated many hundred miles at a stretch, and if we suppose the shell
+to be partially protected in the crevice of a log of wood, and to be thus
+out of water in calm weather, the distance might extend to a thousand miles
+or more. The eggs of fresh-water mollusca, as well as the young animals,
+are known to attach themselves to the feet of aquatic birds, and this is
+probably the most efficient cause of their very wide diffusion.
+
+[16] _Principles of Geology_, 11th Ed., Vol. I., p. 258.
+
+[17] On Limestone as an Index of Geological Time.
+
+[18] In his _Preliminary Report on Oceanic Deposit_, Mr. Murray says:--"It
+has been found that the deposits taking place near continents and islands
+have received their chief characteristics from the presence of the _debris_
+of adjacent lands. In some cases these deposits extend to a distance of
+over 150 miles from the coast." (_Proceedings of the Royal Society_, Vol.
+XXIV. p. 519.)
+
+"The materials in suspension appear to be almost entirely deposited within
+200 miles of the land." (_Proceedings of the Royal Society of Edinburgh_,
+1876-77, p. 253.)
+
+[19] _Geographical Evolution. (Proceedings of the Royal Geographical
+Society._ 1879, p. 426.)
+
+[20] Professor Dana was, I believe, the first to point out that the regions
+which, after long undergoing subsidence and accumulating vast piles of
+sedimentary deposit have been elevated into mountain ranges, thereby become
+stiff and unyielding, and that the next depression and subsequent upheaval
+will be situated on one or the other sides of it; and he has shown that, in
+North America, this is the case with all the mountains of the successive
+geological formations. Thus, depressions, and elevations of extreme
+slowness but often of vast amount, have occurred successively in restricted
+adjacent areas; and the effect has been to bring each portion in succession
+beneath the ocean but always bordered on one or both sides by the remainder
+of the continent, from the denudation of which the deposits are formed
+which, on the subsequent upheaval, become mountain ranges. (_Manual of
+Geology_, 2nd Ed., p. 751.)
+
+[21] _Nature_, Vol. II., p. 297.
+
+[22] Sir W. Thomson, _Voyage of Challenger_, Vol. II., p. 374.
+
+[23] The following is the analysis of the chalk at Oahu:--
+
+ Carbonate of Lime 92.800 per cent.
+ Carbonate of Magnesia 2.385 ,,
+ Alumina 0.250 ,,
+ Oxide of Iron 0.543 ,,
+ Silica 0.750 ,,
+ Phosphoric Acid and Fluorine 2.113 ,,
+ Water and loss 1.148 ,,
+
+This chalk consists simply of comminuted corals and shells of the reef. It
+has been examined microscopically and found to be destitute of the minute
+organisms abounding in the chalk of England. (_Geology of the United States
+Exploring Expedition_, p. 150.) Mr. Guppy also found chalk-like coral
+limestones containing 95 p.c. of carbonate of lime in the Solomon Islands.
+
+The absence of _Globigerinæ_ is a local phenomenon. They are quite absent
+in the Arafura Sea, and no _Globigerina_-ooze was found in any of the
+enclosed seas of the Pacific, but with these exceptions the _Globigerinæ_
+"are really found all over the bottom of the ocean." (Murray on Oceanic
+Deposits--_Proceedings of Royal Society_, Vol. XXIV., p. 523.)
+
+The above analysis shows a far closer resemblance to chalk than that of the
+_Globigerina_-ooze of the Atlantic, four specimens of which given by Sir W.
+Thomson (_Voyage of the Challenger_ Vol. II. Appendix, pp. 374-376, Nos. 9,
+10, 11 and 12) from the mid-Atlantic, show the following proportions:--
+
+ Carbonate of Lime 43.93 to 79.17 per cent.
+ Carbonate of Magnesia 1.40 to 2.58 ,,
+ Alumina and Oxide of Iron 6.00? to 32.98 ,,
+ Silica 4.60 to 11.23 ,,
+
+In addition to the above there is a quantity of insoluble residue
+consisting of small particles of sanidine, augite, hornblende, and
+magnetite, supposed to be the product of volcanic dust or ashes carried
+either in the air or by ocean currents. This volcanic matter amounts to
+from 4.60 to 8.33 per cent. of the _Globigerina_-ooze of the mid-Atlantic,
+where it seems to be always present; and the small proportion of similar
+matter in true chalk is another proof that its origin is different, and
+that it was deposited far more rapidly than the oceanic ooze.
+
+The following analysis of chalk by Mr. D. Forbes will show the difference
+between the two formations:--
+
+ Grey Chalk, White Chalk,
+ _Folkestone_. _Shoreham_.
+
+ Carbonate of Lime 94.09 98.40
+ Carbonate of Magnesia 0.31 0.08
+ Alumina and Phosphoric Acid a trace 0.42
+ Chloride of Sodium 1.29 --
+ Insoluble débris 3.61 1.10
+
+(From _Quarterly Journal of the Geological Society_, Vol. XXVII.)
+
+The large proportion of carbonate of lime, and the very small quantity of
+silica, alumina, and insoluble _débris_, at once distinguish true chalk
+from the _Globigerina_-ooze of the deep ocean bed.
+
+[24] Notes on Reticularian Rhizopoda; in _Microscopical Journal_, Vol.
+XIX., New Series, p. 84.
+
+[25] _Proceedings of the Royal Society_, Vol. XXIV. p. 532.
+
+[26] See Presidential Address in Sect. D. of British Association at
+Plymouth, 1877.
+
+[27] _Geological Magazine_, 1871, p. 426.
+
+[28] In his lecture on _Geographical Evolution_ (which was published after
+the greater part of this chapter had been written) Sir Archibald Geikie
+expresses views in complete accordance with those here advocated. He
+says:--"The next long era, the Cretaceous, was more remarkable for slow
+accumulation of rock under the sea than for the formation of new land.
+During that time the Atlantic sent its waters across the whole of Europe
+and into Asia. But they were probably nowhere more than a few hundred feet
+deep over the site of our continent, even at their deepest part. Upon their
+bottom there gathered a vast mass of calcareous mud, composed in great part
+of foraminifera, corals, echinoderms, and molluscs. Our English chalk,
+which ranges across the north of France, Belgium, Denmark, and the north of
+Germany, represents a portion of the deposits of that sea-floor." The
+weighty authority of the Director-General of the Geological Survey may
+perhaps cause some geologists to modify their views as to the deep-sea
+origin of chalk, who would have treated any arguments advanced by myself as
+not worthy of consideration.
+
+[29] _Introduction and Succession of Vertebrate Life in America_, by
+Professor O. C. Marsh. Reprinted from the _Popular Science Monthly_, March,
+April, 1878.
+
+[30] _Physical Geography and Geology of Great Britain_, 5th Ed. p. 61.
+
+[31] Of late it has been the custom to quote the so-called "ridge" down the
+centre of the Atlantic as indicating an extensive ancient land. Even
+Professor Judd at one time adopted this view, speaking of the great belt of
+Tertiary volcanoes "which extended through Greenland, Iceland, the Faroe
+Islands, the Hebrides, Ireland, Central France, the Iberian Peninsula, the
+Azores, Madeira, Canaries, Cape de Verde Islands, Ascension, St. Helena,
+and Tristan d'Acunha, and which constituted as shown by the recent
+soundings of H.M.S. _Challenger_ a mountain-range, comparable in its
+extent, elevation, and volcanic character with the Andes of South America"
+(_Geological Mag._ 1874, p. 71). On examining the diagram of the Atlantic
+Ocean in the _Challenger Reports_, No. 7, a considerable part of this ridge
+is found to be more than 1,900 fathoms deep, while the portion called the
+"Connecting Ridge" seems to be due in part to the deposits carried out by
+the River Amazon. In the neighbourhood of the Azores, St. Paul's Rocks,
+Ascension, and Tristan d'Acunha are considerable areas varying from 1,200
+to 1,500 fathoms deep, while the rest of the ridge is usually 1,800 or
+1,900 fathoms. The shallower water is no doubt due to volcanic upheaval and
+the accumulation of volcanic ejections, and there may be many other deeply
+submerged old volcanoes on the ridge; but that it ever formed a chain of
+mountains "comparable in elevation with the Andes," there seems not a
+particle of evidence to prove. It is however probable that this ridge
+indicates the former existence of some considerable Atlantic islands, which
+may serve to explain the presence of a few identical genera, and even
+species of plants and insects in Africa and South America, while the main
+body of the fauna and flora of these two continents remains radically
+distinct.
+
+In my _Darwinism_ (pp. 344-5) I have given an additional argument founded
+on the comparative height and area of land with the depth and area of
+ocean, which seems to me to add considerably to the weight of the evidence
+here submitted for the permanence of oceanic and continental areas.
+
+[32] In a review of Mr. T. Mellard Reade's _Chemical Denudation and
+Geological Time_, in _Nature_ (Oct. 2nd, 1879), the writer remarks as
+follows:--"One of the funny notions of some scientific thinkers meets with
+no favour from Mr. Reade, whose geological knowledge is practical as well
+as theoretical. They consider that because the older rocks contain nothing
+like the present red clays, &c., of the ocean floor, that the oceans have
+always been in their present positions. Mr. Reade points out that the first
+proposition is not yet proved, and the distribution of animals and plants
+and the fact that the bulk of the strata on land are of marine origin are
+opposed to the hypothesis." We must leave it to our readers to decide
+whether the "notion" developed in this chapter is "funny," or whether such
+hasty and superficial arguments as those here quoted from a "practical
+geologist" have any value as against the different classes of facts, all
+pointing to an opposite conclusion, which have now been briefly laid before
+them, supported as they are by the expressed opinion of so weighty an
+authority as Sir Archibald Geikie, who, in the lecture already quoted
+says:--"From all this evidence we may legitimately conclude that the
+present land of the globe, though formed in great measure of marine
+formations, has never lain under the deep sea; but that its site must
+always have been near land. Even its thick marine limestones are the
+deposits of comparatively shallow water."
+
+[33] _Antiquity of Man_, 4th Ed. pp. 340-348.
+
+[34] _The Great Ice Age and its Relation to the Antiquity of Man._ By James
+Geikie, F.R.S. (Isbister and Co., 1874.)
+
+[35] This view of the formation of "till" is that adopted, by Dr. Geikie,
+and upheld by almost all the Scotch, Swiss, and Scandinavian geologists.
+The objection however is made by many eminent English geologists, including
+the late Mr. Searles V. Wood, Jun., that mud ground off the rocks cannot
+remain beneath the ice, forming sheets of great thickness, because the
+glacier cannot at the same time grind down solid rock and yet pass over the
+surface of soft mud and loose stones. But this difficulty will disappear if
+we consider the numerous fluctuations in the glacier with increasing size,
+and the additions it must have been constantly receiving as the ice from
+one valley after another joined together, and at last produced an ice-sheet
+covering the whole country. The grinding power is the motion and pressure
+of the ice, and the pressure will depend on its thickness. Now the points
+of maximum thickness must have often changed their positions, and the
+result would be that the matter ground out in one place would be forced
+into another place where the pressure was less. If there were no lateral
+escape for the mud, it would necessarily support the ice over it just as a
+water-bed supports the person lying on it; and when there was little
+drainage water, and the ice extended, say, twenty miles in every direction
+from a given part of a valley where the ice was of less than the average
+thickness, the mud would necessarily accumulate at this part simply because
+there was no escape for it. Whenever the pressure all round any area was
+greater than the pressure on that area, the _débris_ of the surrounding
+parts would be forced into it, and would even raise up the ice to give it
+room. This is a necessary result of hydrostatic pressure. During this
+process the superfluous water would no doubt escape through fissures or
+pores of the ice, and would leave the mud and stones in that excessively
+compressed and tenacious condition in which the "till" is found. The
+unequal thickness and pressure of the ice above referred to would be a
+necessary consequence of the inequalities in the valleys, now narrowing
+into gorges, now opening out into wide plains, and again narrowed lower
+down; and it is just in these openings in the valleys that the "till" is
+said to be found, and also in the lowlands where an ice-sheet must have
+extended for many miles in every direction. In these lowland valleys the
+"till" is both thickest and most wide-spread, and this is what we might
+expect. At first, when the glaciers from the mountains pushed out into
+these valleys, they would grind out the surface beneath them into hollows,
+and the drainage-water would carry away the _débris_. But when they spread
+all over the surface from sea to sea, and there was little or no drainage
+water compared to the enormous area covered with ice, the great bulk of the
+_débris_ must have gathered under the ice wherever the pressure was least,
+and the ice would necessarily rise as it accumulated. Some of the mud would
+no doubt be forced out along lines of least resistance to the sea, but the
+friction of the stone-charged "till" would be so enormous that it would be
+impossible for any large part of it to be disposed of in this way.
+
+[36] That the ice-sheet was continuous from Scotland to Ireland is proved
+by the glacial phenomena in the Isle of Man, where "till" similar to that
+in Scotland abounds, and rocks are found in it which must have come from
+Cumberland and Scotland, as well as from the north of Ireland. This would
+show that glaciers from each of these districts reached the Isle of Man,
+where they met and flowed southwards down the Irish Sea. Ice-marks are
+traced over the tops of the mountains which are nearly 2,000 feet high.
+(See _A Sketch of the Geology of the Isle of Man_, by John Horne, F.G.S.
+_Trans. of the Edin. Geol. Soc._ Vol. II. pt. 3, 1874.)
+
+[37] _The Great Ice Age_, p. 177.
+
+[38] These are named, in descending order, Hessle Boulder Clay, Purple
+Boulder Clay, Chalky Boulder Clay, and Lower Boulder Clay--below which is
+the Norwich Crag.
+
+[39] "On the Climate of the Post-Glacial Period." _Geological Magazine_,
+1872, pp. 158, 160.
+
+[40] _Geological Magazine_, 1876, p. 396.
+
+[41] _Early Man in Britain and his Place in the Tertiary Period_, p. 113.
+
+[42] Heer's _Primæval World of Switzerland_ Vol. II., pp. 148-168.
+
+[43] Dr. James Geikie in _Geological Magazine_, 1878, p. 77.
+
+[44] This subject is admirably discussed in Professor Asa Gray's Lecture on
+"Forest Geography and Archæology" in the _American Journal of Science and
+Arts_, Vol. XVI. 1878.
+
+[45] In a letter to _Nature_ of October 30th, 1879, the Rev. O. Fisher
+calls attention to a result arrived at by Pouillet, that the temperature
+which the surface of the ground would assume if the sun were extinguished
+would be -128° F. instead of -239° F. If this corrected amount were used in
+our calculations, the January temperature of England during the glacial
+epoch would come out 17° F., and this Mr. Fisher thinks not low enough to
+cause any extreme difference from the present climate. In this opinion,
+however, I cannot agree with him. On the contrary, it would, I think, be a
+relief to the theory were the amounts of decrease of temperature in winter
+and increase in summer rendered more moderate, since according to the usual
+calculation (which I have adopted) the differences are unnecessarily great.
+I cannot therefore think that this modification of the temperatures, should
+it be ultimately proved to be correct (which is altogether denied by Dr.
+Croll), would be any serious objection to the adoption of Dr. Croll's
+theory of the Astronomical and Physical causes of the Glacial Epoch.
+
+The reason of the theoretical increase of summer heat being greater than
+the decrease of winter cold is because we are now nearest the sun in winter
+and farthest in summer, whereas we calculate the temperatures of the
+glacial epoch for the phase of precession when the _aphelion_ was in
+winter. A large part of the increase of temperature would no doubt be used
+up in melting ice and evaporating water, so that there would be a much less
+increase of sensible heat; while only a portion of the theoretical lowering
+of temperature in winter would be actually produced owing to equalising
+effect of winds and currents, and the storing up of heat by the earth and
+ocean.
+
+[46] Dr. Croll says this "is one of the most widespread and fundamental
+errors within the whole range of geological climatology." The temperature
+of the snow itself is, he says, one of the main factors. (_Climate and
+Cosmology_, p. 85.) But surely the temperature of the snow must depend on
+the temperature of the air through which it falls.
+
+[47] In an account of Prof. Nordenskjöld's recent expedition round the
+northern coast of Asia, given in _Nature_, November 20th, 1879, we have the
+following passage, fully supporting the statement in the text. "Along the
+whole coast, from the White Sea to Behring's Straits, no glacier was seen.
+During autumn the Siberian coast is nearly free of ice and snow. There are
+no mountains covered all the year round with snow, although some of them
+rise to a height of more than 2,000 feet." It must be remembered that the
+north coast of Eastern Siberia is in the area of supposed greatest winter
+cold on the globe.
+
+[48] Dr. Croll objects to this argument on the ground that Greenland and
+the Antarctic continent are probably lowlands or groups of islands.
+(_Climate and Cosmology_, Chap. V.)
+
+[49] "On the Glacial Epoch," by James Croll. _Geol. Mag._ July, August,
+1874.
+
+[50] "The general absence of recent marks of glacial action in Eastern
+Europe is well known; and the series of changes which have been so well
+traced and described by Prof. Szabó as occurring in those districts seems
+to leave no room for those periodical extensions of 'ice-caps' with which
+some authors in this country have amused themselves and their readers. Mr.
+Campbell, whose ability to recognise the physical evidence of glaciers will
+scarcely be questioned, finds quite the same absence of the proof of
+extensive ice-action in North America, westward of the meridian of
+Chicago." (Prof. J. W. Judd in _Geol. Mag._ 1876, p. 535.)
+
+The same author notes the diminution of marks of ice-action on going
+eastward in the Alps; and the Altai Mountains far in Central Asia show no
+signs of having been largely glaciated. West of the Rocky Mountains,
+however, in the Sierra Nevada and the coast ranges further north, signs of
+extensive old glaciers again appear; all which phenomena are strikingly in
+accordance with the theory here advocated, of the absolute dependence of
+glaciation on abundant rainfall and elevated snow-condensers and
+accumulators.
+
+[51] I have somewhat modified this whole passage in the endeavour to
+represent more accurately the difference between the views of Dr. Croll and
+Sir Charles Lyell.
+
+[52] For numerous details and illustrations see the paper--"On Ocean
+Currents in Relation to the Physical Theory of Secular Changes of
+Climate"--in the _Philosophical Magazine_, 1870.
+
+[53] See _Darwin's Naturalist's Voyage Round the World_, 2nd Edition, pp.
+244-251.
+
+[54] The influence of geographical changes on climate is now held by many
+geologists who oppose what they consider the extravagant hypotheses of Dr.
+Croll. Thus, Prof. Dana imputes the glacial epoch chiefly, if not wholly,
+to elevation of the land caused by the lateral pressure due to shrinking of
+the earth's crust that has caused all other elevations and depressions. He
+says: "Now, that elevation of the land over the higher latitudes which
+brought on the glacial era is a natural result of the same agency, and a
+natural, and almost necessary, counterpart of the coral-island subsidence
+which must have been then in progress. The accumulating, folding,
+solidification, and crystallisation of rocks attending all the rock-making
+and mountain-making through the Palæozoic, Mesozoic, and Cenozoic eras, had
+greatly stiffened the crust in these parts; and hence in after times, the
+continental movements resulting from the lateral pressure necessarily
+appeared over the more northern portions of the continent, where the
+accumulations and other changes had been relatively small. To the
+subsidence which followed the elevation the weight of the ice-cap may have
+contributed in some small degree. But the great balancing movements of the
+crust of the continental and oceanic areas then going forward must have had
+a greatly preponderating effect in the oscillating agency of all
+time--lateral pressure within the crust." (_American Journal of Science and
+Arts_, 3rd Series, Vol. IX. p. 318.)
+
+"In the 2nd edition of his _Manual of Geology_, Professor Dana suggests
+elevation of Arctic lands sufficient to exclude the Gulf Stream, as a
+source of cold during glacial epochs. This, he thinks, would have made an
+epoch of cold at any era of the globe. A deep submergence of Behring's
+Strait, letting in the Pacific warm current to the polar area, would have
+produced a mild Arctic climate like that of the Miocene period. When the
+warm current was shut out from the polar area it would yet reach near to
+it, and bring with it that abundant moisture necessary for glaciation."
+(_Manual of Geology_, 2nd Edition, pp. 541-755, 756.)
+
+[55] Dana's _Manual of Geology_, 2nd Edition, p. 540.
+
+[56] Dr. Croll says that I here assume an impossible state of things. He
+maintains "that the change from the distant sun in winter, and near sun in
+summer to the near sun in winter and distant sun in summer, aided by the
+change in the physical causes which this would necessarily bring about,
+would certainly be sufficient to cause the snow and ice to disappear."
+(_Climate and Cosmology_, p. 106.) But I demur to his "necessarily." It is
+not the _direct_ effect of the nearer sun in winter that is supposed to
+melt the snow and ice, but the "physical causes," such as absence of fogs
+and increase of warm equatorial currents. But the near sun in winter acting
+on an ice-clad surface would only increase the fogs and snow, while the
+currents could only change if a large portion of the ice were first melted,
+in which case they would no doubt be modified so as to cause a further
+melting of the ice. Dr. Croll says: "The warm and equable conditions of
+climate which would then prevail, and the enormous quantity of
+intertropical water carried into the Southern Ocean, would soon produce a
+melting of the ice." (_Loc. cit._ p. 111.) This seems to me to be assuming
+the very point at issue. He has himself shown that the presence of large
+quantities of ice prevents "a warm and equable climate" however great may
+be the sun-heat; the ice therefore would _not_ be melted, and there would
+be no increased flow of intertropical water to the Southern Ocean. The
+ocean currents are mainly due to the difference of temperature of the polar
+and equatorial areas combined with the peculiar form and position of the
+continents, and some one or more of these factors must be altered _before_
+the ocean currents towards the north pole can be increased. The only factor
+available is the Antarctic ice, and if this were largely increased, the
+northward-flowing currents might be so increased as to melt some of the
+Arctic ice. But the very same argument applies to both poles. Without some
+geographical change the Antarctic ice could not materially diminish during
+its winter in _perihelion_, nor increase to any important extent during the
+opposite phase. We therefore seem to have no available agency by which to
+get rid of the ice over a glaciated hemisphere, _so long as the
+geographical conditions remained unchanged and the excentricity continued
+high_.
+
+[57] In the _Geological Magazine_, April, 1880, Mr. Searles V. Wood adduces
+what he considers to be the "conclusive objection" to Dr. Croll's
+excentricity theory, which is, that during the last glacial epoch Europe
+and North America were glaciated very much in proportion to their
+respective climates now, which are generally admitted to be due to the
+distribution of oceanic currents. But Dr. Croll admits his theory "to be
+baseless unless there was a complete diversion of the warm ocean currents
+from the hemisphere glaciated," in which case there ought to be no
+difference in the extent of glaciation in Europe and North America. Whether
+or not this is a correct statement of Dr. Croll's theory, the above
+objection certainly does not apply to the views here advocated; but as I
+also hold the "excentricity theory" in a modified form, it may be as well
+to show why it does not apply. In the first place I do not believe that the
+Gulf Stream was "completely diverted" during the glacial epoch, but that it
+was diminished in force, and (as described at p. 144) _partly_ diverted
+southward. A portion of its influence would, however, still remain to cause
+a difference between the climates of the two sides of the Atlantic; and to
+this must be added two other causes--the far greater penetration of warm
+sea-water into the European than into the North American continent, and the
+proximity to America of the enormous ice-producing mass of Greenland. We
+have thus three distinct causes, all combining to produce a more severe
+winter climate on the west than on the east of the Atlantic during the
+glacial epoch, and though the first of these--the Gulf Stream--was not
+nearly so powerful as it is now, neither is the difference indicated by the
+ice-extension in the two countries so great as the present difference of
+winter-temperature, which is the essential point to be considered. The
+ice-sheet of the United States is usually supposed to have extended about
+ten, or, at most, twelve, degrees further south than it did in Western
+Europe, whereas we must go twenty degrees further south in the former
+country to obtain the same mean winter-temperature we find in the latter,
+as may be seen by examining any map of winter isothermals. This difference
+very fairly corresponds to the difference of conditions existing during the
+glacial epoch and the present time, so far as we are able to estimate them,
+and it certainly affords no grounds of objection to the theory by which the
+glaciation is here explained.
+
+[58] Dr. Croll objects to this argument, and adduces the case of Greenland
+as showing that ice may accumulate far from sea. But the width of Greenland
+is small compared with that of the supposed Antarctic ice-cap. (_Climate
+and Cosmology_, p. 78.)
+
+[59] The recent extensive glaciation of New Zealand is generally imputed by
+the local geologists to a greater elevation of the land; but I cannot help
+believing that the high phase of excentricity which caused our own glacial
+epoch was at all events an assisting cause. This is rendered more probable
+if taken in connection with the following very definite statement of
+glacial markings in South Africa. Captain Aylward in his _Transvaal of
+To-day_ (p. 171) says:--"It will be interesting to geologists and others to
+learn that the entire country, from the summits of the Quathlamba to the
+junction of the Vaal and Orange rivers, shows marks of having been swept
+over, and that at no very distant period, by vast masses of ice from east
+to west. The striations are plainly visible, scarring the older rocks, and
+marking the hill-sides--getting lower and lower and less visible as,
+descending from the mountains, the kopjies (small hills) stand wider apart;
+but wherever the hills narrow towards each other, again showing how the
+vast ice-fields were checked, thrown up, and raised against their Eastern
+extremities."
+
+This passage is evidently written by a person familiar with the phenomena
+of glaciation, and as Captain Aylward's preface is dated from Edinburgh, he
+has probably seen similar markings in Scotland. The country described
+consists of the most extensive and lofty plateau in South Africa, rising to
+a mountain knot with peaks more than 10,000 feet high, thus offering an
+appropriate area for the condensation of vapour and the accumulation of
+snow. At present, however, the mountains do not reach the snow-line, and
+there is no proof that they have been much higher in recent times, since
+the coast of Natal is now said to be rising. It is evident that no slight
+elevation would now lead to the accumulation of snow and ice in these
+mountains, situated as they are between 27° and 30° S. Lat.; since the
+Andes, which in 32° S. Lat. reach 23,300 feet high, and in 28° S. Lat.
+20,000, with far more extensive plateaus, produce no ice-fields. We cannot,
+therefore, believe that a few thousand feet of additional elevation, even
+if it occurred so recently as indicated by the presence of striations,
+would have produced the remarkable amount of glaciation above described;
+while from the analogy of the northern hemisphere, we may well believe that
+it was mainly due to the same high excentricity that led to the glaciation
+of Western and Central Europe, and Eastern North America.
+
+These observations confirm those of Mr. G. W. Stow, who, in a paper
+published in the _Quarterly Journal of the Geological Society_ (Vol. XXVII.
+p. 539), describes similar phenomena in the same mountains, and also mounds
+and ridges of unstratified clay packed with angular boulders; while further
+south the Stormberg mountains are said to be similarly glaciated, with
+immense accumulations of morainic matter in all the valleys. We have here
+most of the surface phenomena characteristic of a glaciated country, only a
+few degrees south of the tropic; and taken in connection with the
+indications of recent glaciation in New Zealand, and those discovered by
+Dr. R. von Lendenfeld in the Australian Alps between 6,000 and 7,000 feet
+elevation (_Nature_, Vol. XXXII. p. 69), we can hardly doubt the occurrence
+of some general and wide-spread cause of glaciation in the southern
+hemisphere at a period so recent that the superficial phenomena are almost
+as well preserved as in Europe. Other geologists however deny that there
+are any distinct indications of glacial action in South Africa; but the
+recent discovery by Dr. J. W. Gregory, F.G.S., of the former extension of
+glaciers on Mount Kenya 5,000 feet below their present limits, renders
+probable the former glaciation of the South African Highlands.
+
+[60] The astronomical facts connected with the motions and appearance of
+the planet are taken from a paper by Mr. Edward Carpenter, M.A., in the
+_Geological Magazine_ of March, 1877, entitled, "Evidence Afforded by Mars
+on the Subject of Glacial Periods," but I arrive at somewhat different
+conclusions from those of the writer of the paper.
+
+[61] In an article in _Nature_ of Jan. 1, 1880, the Rev. T. W. Webb states
+that in 1877 the pole of Mars (? the south pole) was, according to
+Schiaparelli, entirely free of snow. He remarks also on the regular contour
+of the supposed snows of Mars as offering a great contrast to ours, and
+also the strongly marked dark border which has often been observed. On the
+whole Mr. Webb seems to be of opinion that there can be no really close
+resemblance between the physical condition of the Earth and Mars, and that
+any arguments founded on such supposed similarity are therefore
+untrustworthy.
+
+[62] _London, Edinburgh and Dublin Philosophical Magazine_, Vol. XXXVI.,
+pp. 144-150 (1868).
+
+[63] _Climate and Time in their Geological Relations_, p. 341.
+
+[64] _Nature_, Vol. XXI., p. 345, "The Interior of Greenland."
+
+[65] Prof. J. W. Judd says: "In the case of the Alps I know of no glacial
+phenomena which are not capable of being explained, like those of New
+Zealand, by a great extension of the area of the tracts above the snow-line
+which would collect more ample supplies for the glaciers protruded into
+surrounding plains. And when we survey the grand panoramas of ridges,
+pinnacles, and peaks produced for the most part by sub-aërial action, we
+may well be prepared to admit that before the intervening ravines and
+valleys were excavated, the glaciers shed from the elevated plateaux must
+have been of vastly greater magnitude than at present." (Contributions to
+the Study of Volcanoes, _Geological Magazine_, 1876, p. 536.) Professor
+Judd applies these remarks to the last as well as to previous glacial
+periods in the Alps; but surely there has been no such extensive alteration
+and lowering of the surface of the country since the erratic blocks were
+deposited on the Jura and the great moraines formed in North Italy, as this
+theory would imply. We can hardly suppose wide areas to have been lowered
+thousands of feet by denudation, and yet have left other adjacent areas
+apparently untouched; and it is even very doubtful whether such an
+extension of the snow-fields would alone suffice for the effects which were
+certainly produced.
+
+[66] _Geological Magazine_, 1876, p. 392.
+
+[67] Colonel Fielden thinks that these trees have all been brought down by
+rivers, and have been stranded on shores which have been recently elevated.
+See _Trans. of Norfolk Nat. Hist. Soc., Vol. III._, 1880.
+
+[68] _Geological Magazine_, 1876, "Geology of Spitzbergen," p. 267.
+
+[69] The preceding account is mostly derived from Professor Heer's great
+work _Flora Fossilis Arctica_.
+
+[70] _Geological Magazine_, 1875, p. 531.
+
+[71] _Geological Magazine_, 1876, p. 266. In his recent work--_Climate and
+Cosmology_ (pp. 164, 172)--the late Dr. Croll has appealed to the
+imperfection of the geological record as a reply to these arguments; in
+this case, as it appears to me, a very unsuccessful one.
+
+[72] It is interesting to observe that the Cretaceous flora of the United
+States (that of the Dakota group), indicates a somewhat cooler climate than
+that of the following Eocene period. Mr. De Rance (in the geological
+appendix to Capt. Sir G. Nares's _Narrative of a Voyage to the Polar Sea_)
+remarks as follows: "In the overlying American Eocenes occur types of
+plants occurring in the European Miocenes and still living, proving the
+truth of Professor Lesquereux's postulate, that the plant types appear in
+America a stage in advance of their advent in Europe. These plants point to
+a far higher mean temperature than those of the Dakota group, to a dense
+atmosphere of vapour, and a luxuriance of ferns and palms." This is very
+important as adding further proof to the view that the climates of former
+periods are not due to any general refrigeration, but to causes which were
+subject to change and alternation in former ages as now.
+
+[73] Mr. S. B. J. Skertchley informs me that he has himself observed thick
+Tertiary deposits, consisting of clays and anhydrous gypsum, at Berenice on
+the borders of Egypt and Nubia, at a height of about 600 feet above the
+sea-level; but these may have been of fresh-water origin.
+
+[74] By referring to our map of the Indian Ocean showing the submarine
+banks indicating ancient islands (Chap. XIX.), it will be evident that the
+south-east trade-winds--then exceptionally powerful--would cause a vast
+body of water to enter the deep Arabian Sea.
+
+[75] In his recently published _Lectures on Physical Geography_, Professor
+Haughton calculates, that more than half the solar heat of the torrid zone
+is carried to the temperate zones by ocean currents. The Gulf Stream itself
+carries one-twelfth of the total amount, but it is probable that a very
+small fraction of this quantity of heat reaches the polar seas owing to the
+wide area over which the current spreads in the North Atlantic. The
+corresponding stream of the Indian Ocean in Miocene times would have been
+fully equal to the Gulf Stream in heating power, while, owing to its being
+so much more concentrated, a large proportion of its heat may have reached
+the polar area. But the Arctic Ocean occupies less than one-tenth of the
+area of the tropical seas; so that, whatever proportion of the heat of the
+tropical zone was conveyed to it, would, by being concentrated into
+one-tenth of the surface, produce an enormously increased effect. Taking
+this into consideration, we can hardly doubt that the opening of a
+sufficient passage from the Indian Ocean to the Arctic seas would produce
+the effects above indicated.
+
+[76] For an account of the resemblances and differences of the mammalia of
+the two continents during the Tertiary epoch, see my _Geographical
+Distribution of Animals_, Vol. I. pp. 140-156.
+
+[77] Professor Haughton has made an elaborate calculation of the difference
+between existing climates and those of Miocene times, for all the places
+where a Miocene flora has been discovered, by means of the actual range of
+corresponding species and genera of plants. Although this method is open to
+the objection that the ranges of plants and animals are not determined by
+temperature only, yet the results may be approximately correct, and are
+very interesting. The following table which summarizes these results is
+taken from his Lectures on Physical Geography (p. 344):--
+
+ _______________________________________________________________________
+ | | | Present | Miocene | |
+ | |Latitude.|Temperature.|Temperature.|Difference.|
+ |_____________________|_________|____________|____________|___________|
+ | 1. Switzerland | 47d.00 | 53d.6 F | 69d.8 F | 16d.2 F |
+ | 2. Dantzig | 54d.21 | 45d.7 ,, | 62d.6 ,, | 16d.9 ,, |
+ | 3. Iceland | 65d.30 | 35d.6 ,, | 48d.2 ,, | 12d.6 ,, |
+ | 4. Mackenzie River | 65d.00 | 19d.4 ,, | 48d.2 ,, | 28d.8 ,, |
+ | 5. Disco (Greenland)| 70d.00 | 19d.6 ,, | 55d.6 ,, | 36d.0 ,, |
+ | 6. Spitzbergen | 78d.00 | 16d.5 ,, | 51d.8 ,, | 35d.3 ,, |
+ | 7. Grinnell Land | 81d.44 | 1d.7 ,, | 42d.3 ,, | 44d.0 ,, |
+ |_____________________|_________|____________|____________|___________|
+
+It is interesting to note that Iceland, which is now exposed to the full
+influence of the Gulf Stream, was only 12°.6 F. warmer in Miocene times,
+while Mackenzie River, now totally removed from its influence was 28°
+warmer. This, as well as, the greater increase of temperature as we go
+northward and the polar area becomes more limited, is quite in accordance
+with the view of the causes which brought about the Miocene climate which
+is here advocated.
+
+[78] The objection has been made, that the long polar night would of itself
+be fatal to the existence of such a luxuriant vegetation as we know to have
+existed as far as 80° N. Lat., and that there must have been some
+alteration of the position of the pole, or diminution of the obliquity of
+the ecliptic, to permit such plants as magnolias and large-leaved maples to
+flourish. But there appears to be really no valid grounds for such an
+objection. Not only are numbers of Alpine and Arctic evergreens deeply
+buried in the snow for many months without injury, but a variety of
+tropical and sub-tropical plants are preserved in the hot-houses of St.
+Petersburg and other northern cities, which are closely matted during
+winter, and are thus exposed to as much darkness as the night of the Arctic
+regions. We have besides no proof that any of the Arctic trees or large
+shrubs were evergreens, and the darkness would certainly not be prejudical
+to deciduous plants. With a suitable temperature there is nothing to
+prevent a luxuriant vegetation up to the pole, and the long continued day
+is known to be highly favourable to the development of foliage, which in
+the same species is larger and better developed in Norway than in the south
+of England.
+
+[79] _Geological Magazine_, 1873, p. 320.
+
+[80] _Geological Magazine_, 1877, p. 137.
+
+[81] _Manual of Geology_, 2nd Ed. p. 525. See also letter in _Nature_, Vol.
+XXIII. p. 410.
+
+[82] _Nature_, Vol. XVIII. (July, 1878), p. 268.
+
+[83] "On the Comparative Value of certain Geological Ages considered as
+items of Geological Time." (_Proceedings of the Royal Society_, 1874, p.
+334.)
+
+[84] _Trans. Royal Society of Edinburgh_, Vol. XXIII. p. 161. _Quarterly
+Journal of Science_, 1877. (Croll on the "Probable Origin and Age of the
+Sun.")
+
+[85] _Philosophical Magazine_, April, 1853.
+
+[86] It has usually been the practice to take the amount of denudation in
+the Mississippi valley, or one foot in six thousand years, as a measure of
+the rate of denudation in Europe, from an idea apparently of being on the
+"safe side," and of not over-estimating the rate of change. But this
+appears to me a most unphilosophical mode of proceeding and unworthy of
+scientific inquiry. What should we think of astronomers if they always took
+the lowest estimates of planetary or stellar distances, instead of the mean
+results of observation, "in order to be on the safe side!"? As if error in
+one direction were any worse than error in another. Yet this is what
+geologists do systematically. Whenever any calculations are made involving
+the antiquity of man, it is those that give the _lowest_ results that are
+always taken, for no reason apparently except that there was, for so long a
+time, a prejudice, both popular and scientific, against the great antiquity
+of man; and now that a means has been found of measuring the rate of
+denudation, they take the slowest rate instead of the mean rate, apparently
+only because there is now a scientific prejudice in favour of extremely
+slow geological change. I take the mean of the whole; and as this is almost
+exactly the same as the mean of the three great European rivers--the Rhone,
+Danube, and Po--I cannot believe that this will not be nearer the truth for
+Europe than taking one North American river as the standard.
+
+[87] "On the Height of the Land and the Depth of the Ocean," in the
+_Scottish Geographical Magazine_, 1888.
+
+[88] These figures are merely used to give an idea of the rate at which
+denudation is actually going on now; but if no elevatory forces were at
+work, the rate of denudation would certainly diminish as the mountains were
+lowered and the slope of the ground everywhere rendered flatter. This would
+follow not only from the diminished power of rain and rivers, but because
+the climate would become more uniform, the rainfall probably less, and no
+rocky peaks would be left to be fractured and broken up by the action of
+frosts. It is certain, however, that no continent has ever remained long
+subject to the influences of denudation alone, for, as we have seen in our
+sixth chapter, elevation and depression have always been going on in one
+part or other of the surface.
+
+[89] The following statement of the depths at which the Palæozoic
+formations have been reached in various localities in and round London was
+given by Mr. H. B. Woodward in his address to the Norwich Geological
+Society in 1879:--
+
+ _Deep Wells through the Tertiary and Cretaceous Formations._
+
+ Harwich at 1,022 feet reached Carboniferous Rock.
+ Kentish Town ,, 1,114 ,, ,, Old Red Sandstone.
+ Tottenham Court Road ,, 1,064 ,, ,, Devonian.
+ Blackwall ,, 1,004 ,, ,, Devonian or Old Red Sandstone.
+ Ware ,, 800 ,, ,, Silurian (Wenlock Shale).
+
+We thus find that over a wide area, extending from London to Ware and
+Harwich, the whole of the formations from the Oolite to the Permian are
+wanting, the Cretaceous resting on the Carboniferous or older Palæozoic
+rocks; and the same deficiency extends across to Belgium, where the
+Tertiary beds are found resting on Carboniferous at a depth of less than
+400 feet.
+
+[90] _Geological Magazine_, Vol. VIII., March, 1871.
+
+[91] Mr. C. Lloyd Morgan has well illustrated this point by comparing the
+generally tilted-up strata denuded on their edges, to a library in which a
+fire had acted on the exposed edges of the books, destroying a great mass
+of literature but leaving a portion of each book in its place, which
+portion represents the thickness but not the size of the book. (_Geological
+Magazine_, 1878, p. 161.)
+
+[92] Professor J. Young thinks it highly probable that--"the Lower
+Greensand is contemporaneous with part of the Chalk, so were parts of the
+Wealden; nay, even of the Purbeck a portion must have been forming while
+the Cretaceous sea was gradually deepening southward and westward." Yet
+these deposits are always arranged successively, and their several
+thicknesses added together to obtain the total thickness of the formations
+of the country. (See Presidential Address, Sect. C. British Association,
+1876.)
+
+[93] Mr. John Murray in his more careful estimate makes it about 51œ
+millions.
+
+[94] As by far the larger portion of the denuded matter of the globe passes
+to the sea through comparatively few great rivers, the deposits must often
+be confined to very limited areas. Thus the denudation of the vast
+Mississippi basin must be almost all deposited in a limited portion of the
+Gulf of Mexico, that of the Nile within a small area of the Eastern
+Mediterranean, and that of the great rivers of China--the Hoang Ho and
+Yang-tse-kiang, in a small portion of the Eastern Sea. Enormous lengths of
+coast, like those of Western America and Eastern Africa, receive very
+scanty deposits; so that thirty miles in width along the whole of the
+coasts of the globe will probably give an area greater than that of the
+area of _average_ deposit, and certainly greater than that of _maximum_
+deposit, which is the basis on which I have here made my estimates. In the
+case of the Mississippi, it is stated by Count Pourtales that along the
+plateau between the mouth of the river and the southern extremity of
+Florida for two hundred and fifty miles in width the bottom consists of
+clay with some sand and but few Rhizopods; but beyond this distance the
+soundings brought up either Rhizopod shells alone, or these mixed with
+coral sand, Nullipores, and other calcareous organisms (Dana's _Manual of
+Geology_, 2nd Ed. p. 671). It is probable, therefore, that a large
+proportion of the entire mass of sediment brought down by the Mississippi
+is deposited on the limited area above indicated.
+
+Professor Dana further remarks: "Over interior oceanic basins as well as
+off a coast in quiet depths, fifteen or twenty fathoms and beyond, the
+deposits are mostly of fine silt, fitted for making fine argillaceous
+rocks, as shales or slates. When, however, the depth of the ocean falls off
+below a hundred fathoms, the deposition of silt in our existing oceans
+mostly ceases, unless in the case of a great bank along the border of a
+continent."
+
+[95] From the same data Professor Haughton estimates a minimum of 200
+million years for the duration of geological time; but he arrives at this
+conclusion by supposing the products of denudation to be uniformly spread
+over the _whole sea-bottom_ instead of over a narrow belt near the coasts,
+a supposition entirely opposed to all the known facts, and which had been
+shown by Dr. Croll, five years previously, to be altogether erroneous. (See
+_Nature_, Vol. XVIII., p. 268, where Professor Haughton's paper is given as
+read before the Royal Society.)
+
+[96] See _Geological Magazine_ for 1877, p. 1.
+
+[97] In his reply to Sir W. Thomson, Professor Huxley _assumed_ one foot in
+a thousand years as a not improbable rate of deposition. The above estimate
+indicates a far higher rate; and this follows from the well-ascertained
+fact, that the area of deposition is many times smaller than the area of
+denudation.
+
+[98] Dr. Croll and Sir Archibald Geikie have shown that marine denudation
+is very small in amount as compared with sub-aërial, since it acts only
+locally on the _edge_ of the land, whereas the latter acts over every foot
+of the _surface_. Mr. W. T. Blanford argues that the difference is still
+greater in tropical than in temperate latitudes, and arrives at the
+conclusion that--"If over British India the effects of marine to those of
+fresh-water denudation in removing the rocks of the country be estimated at
+1 to 100, I believe that the result of marine action will be greatly
+overstated" (_Geology and Zoology of Abyssinia_, p. 158, note). Now, as our
+estimate of the rate of sub-aërial denudation cannot pretend to any precise
+accuracy, we are justified in neglecting marine denudation altogether,
+especially as we have no method of estimating it for the whole earth with
+any approach to correctness.
+
+[99] Agassiz appears to have been the first to suggest that the principal
+epochs of life extermination were epochs of cold; and Dana thinks that two
+at least such epochs may be recognised, at the close of the Palæozoic and
+of the Cretaceous periods--to which we may add the last glacial epoch.
+
+[100] This view was, I believe, first put forth by myself in a paper read
+before the Geological Section of the British Association in 1869, and
+subsequently in an article in _Nature_, Vol. I. p. 454. It was also stated
+by Mr. S. B. J. Skertchley in his _Physical System of the Universe_, p. 363
+(1878); but we both founded it on what I now consider the erroneous
+doctrine that actual glacial epochs recurred each 10,500 years during
+periods of high excentricity.
+
+[101] Explication d'une seconde édition de la _Carte Géologique de la
+Terre_ (1875), p. 64.
+
+[102] For most of the facts as to the zoology and botany of these islands,
+I am indebted to Mr. Godman's valuable work--_Natural History of the Azores
+or Western Islands_, by Frederick Du Cane Godman, F.L.S., F.Z.S., &c.,
+London, 1870.
+
+[103] See Chap. V. p. 78.
+
+[104] Some of Mr. Darwin's experiments are very interesting and suggestive.
+Ripe hazel-nuts sank immediately, but when dried they floated for ninety
+days, and afterwards germinated. An asparagus-plant with ripe berries, when
+dried, floated for eighty-five days, and the seeds afterwards germinated.
+Out of ninety-four dried plants experimented with, eighteen floated for
+more than a month, and some for three months, and their powers of
+germination seem never to have been wholly destroyed. Now, as oceanic
+currents vary from thirty to sixty miles a day, such plants under the most
+favourable conditions might be carried 90 X 60 = 5,400 miles! But even half
+of this is ample to enable them to reach any oceanic island, and we must
+remember that till completely water-logged they might be driven along at a
+much greater rate by the wind. Mr. Darwin calculates the distance by the
+average time of flotation to be 924 miles; but in such a case as this we
+are entitled to take the extreme cases, because such countless thousands of
+plants and seeds must be carried out to sea annually that the extreme cases
+in a single experiment with only ninety-four plants, must happen hundreds
+or thousands of times and with hundreds or thousands of species, naturally,
+and thus afford ample opportunities for successful migration. (See _Origin
+of Species_, 6th Edition, p. 325.)
+
+[105] The following remarks, kindly communicated to me by Mr. H. N.
+Moseley, naturalist to the _Challenger_, throw much light on the agency of
+birds in the distribution of plants:--"Grisebach (_Veg. der Erde_, Vol. II.
+p. 496) lays much stress on the wide ranging of the albatross (Diomedea)
+across the equator from Cape Horn to the Kurile Islands, and thinks that
+the presence of the same plants in Arctic and Antarctic regions may be
+accounted for, possibly, by this fact. I was much struck at Marion Island
+of the Prince Edward group, by observing that the great albatross breeds in
+the midst of a dense, low herbage, and constructs its nest of a mound of
+turf and herbage. Some of the indigenous plants, _e.g._ Acæna, have
+flower-heads which stick like burrs to feathers, &c., and seem specially
+adapted for transposition by birds. Besides the albatrosses, various
+species of Procellaria and Puffinus, birds which range over immense
+distances may, I think, have played a great part in the distribution of
+plants, and especially account, in some measure, for the otherwise
+difficult fact (when occurring in the tropics), that widely distant islands
+have similar mountain plants. The Procellaria and Puffinus in nesting,
+burrow in the ground, as far as I have seen choosing often places where the
+vegetation is the thickest. The birds in burrowing get their feathers
+covered with vegetable mould, which must include spores, and often seeds.
+In high latitudes the birds often burrow near the sea-level, as at Tristan
+d'Acunha or Kerguelen's Land, but in the tropics they choose the mountains
+for their nesting-place (Finsch and Hartlaub, _Orn. der Viti- und
+Tonga-Inseln_, 1867, Einleitung, p. xviii.). Thus, _Puffinus megasi_ nests
+at the top of the Korobasa basaga mountain, Viti Levu, fifty miles from the
+sea. A Procellaria breeds in like manner in the high mountains of Jamaica,
+I believe at 7,000 feet. Peale describes the same habit of _Procellaria
+rostrata_ at Tahiti, and I saw the burrows myself amidst a dense growth of
+fern, &c., at 4,400 feet elevation in that island. Phaethon has a similar
+habit. It nests at the crater of Kilauea, Hawaii, at 4,000 feet elevation,
+and also high up in Tahiti. In order to account for the transportation of
+the plants, it is not of course necessary that the same species of
+Procellaria or Diomedea should now range between the distant points where
+the plants occur. The ancestor of the now differing species might have
+carried the seeds. The range of the genus is sufficient."
+
+[106] _Nature_, Vol. VI. p. 262, "Recent Observations in the Bermudas," by
+Mr. J. Matthew Jones.
+
+[107] "The late Sir C. Wyville Thomson was of opinion that the 'red earth'
+which largely forms the soil of Bermuda had an organic origin, as well as
+the 'red clay' which the _Challenger_ discovered in all the greater depths
+of the ocean basins. He regarded the red earth and red clay as an ash left
+behind after the gradual removal of the lime by water charged with carbonic
+acid. This ash he regarded as a constituent part of the shells of
+Foraminifera, skeletons of Corals, and Molluscs, [_vide_ _Voyage of the
+Challenger_, Atlantic, Vol. I. p. 316]. This theory does not seem to be in
+any way tenable. Analysis of carefully selected shells of Foraminifera,
+Heteropods, and Pteropods, did not show the slightest trace of alumina, and
+none has as yet been discovered in coral skeletons. It is most probable
+that a large part of the clayey matter found in red clay and the red earth
+of Bermuda is derived from the disintegration of pumice, which is
+continually found floating on the surface of the sea. [See Murray, "On the
+Distribution of Volcanic Débris Over the Floor of the Ocean;" _Proc. Roy.
+Soc. Edin._ Vol. IX. pp. 247-261. 1876-1877.] The naturalists of the
+_Challenger_ found it among the floating masses of gulf weed, and it is
+frequently picked up on the reefs of Bermuda and other coral islands. The
+red earth contains a good many fragments of magnetite, augite, felspar, and
+glassy fragments, and when a large quantity of the rock of Bermuda is
+dissolved away with acid, a small number of fragments are also met with.
+These mineral particles most probably came originally from the pumice which
+had been cast up on the island for long ages (for it is known that these
+minerals are present in pumice), although possibly some of them may have
+come from the volcanic rock, which is believed to form the nucleus of the
+island." _The Voyage of H.M.S. Challenger_, Narrative of the Cruise, Vol.
+I. 1885, pp. 141-142.
+
+[108] Four bats occur rarely, two being N. American, and two West Indian
+Species. _The Bermuda Islands_, by Angelo Heilprin, Philadelphia, 1889.
+
+[109] Fourteen species of Spiders were collected by Prof. A. Heilprin, all
+American or cosmopolitan species except one, _Lycosa atlantica_, which Dr.
+Marx of Washington describes as new and as peculiar to the islands.
+(Heilprin's _The Bermudas_, p. 93.)
+
+[110] Mr. Theo. D. A. Cockerell informs me that there are two slugs in
+Bermuda of which specimens exist in the British Museum,--_Amalia gagates_
+Drap. common in Europe, and _Agriolimax campestris_ of the United States.
+Both may therefore have been introduced by human agency. Also _Vaginulus
+Morelete var. schivelyæ_ which seems to be a variety of a Mexican species;
+perhaps imported.
+
+[111] "Notes on the Vegetation of Bermuda," by H. N. Moseley. (_Journal of
+the Linnean Society_, Vol. XIV., _Botany_, p. 317.)
+
+[112] _Gigantic Land Tortoises Living and Extinct in the Collection of the
+British Museum._ By A. C. L. G. Günther, F.R.S. 1877.
+
+[113] The following list of the beetles yet known from the Galapagos shows
+their scanty proportions and accidental character; the forty species
+belonging to thirty-three genera and eighteen families. It is taken from
+Mr. Waterhouse's enumeration in the _Proceedings of the Zoological Society_
+for 1877 (p. 81), with a few additions collected by the U. S. Fish
+Commission Steamer _Albatross_, and published by the U. S. National Museum
+in 1889.
+
+ CARABIDÆ. ELATERIDÆ.
+ Feronia calathoides. Physorhinus galapagoensis
+ ,, insularis. HETEROMERA.
+ ,, galapagoensis. Allecula n. s.
+ Amblygnathus obscuricornis. Stomion helopoides.
+ Solenophorus galapagoensis. ,, lævigatum.
+ Notaphus galapagoensis. Ammophorus obscurus.
+ DYTISCIDÆ. ,, cooksoni.
+ Eunectes occidentalis. ,, bifoveatus.
+ Acilius incisus. Pedonoeces galapagoensis.
+ Copelatus galapagoensis. ,, pubescens.
+ PALPICORNES. Phaleria manicata.
+ Tropisternus lateralis. CURCULIONIDÆ.
+ Philhydrus sp. Otiorhynchus cuneiformis.
+ STAPHYLINIDÆ. Anchonus galapagoensis.
+ Creophilus villosus. LONGICORNIA.
+ NECROPHAGA. Mallodou sp.
+ Acribis serrativentris. Eburia amabilis.
+ Phalacrus darwinii. ANTHRIBIDÆ.
+ Dermestes vulpinus. Ormiscus variegatus.
+ MALACODERMS. PHYTOPHAGA
+ Ablechrus darwinii. Diabrotica limbata.
+ Corynetes rufipes. Docema galapagoensis.
+ Bostrichus unciniatus. Longitarsus lunatus.
+ Tetrapriocerca sp. SECURIPALPES.
+ LAMELLICORNES. Scymuns galapagoensis.
+ Copris lugubris.
+ Oryctes galapagoensis.
+
+[114] Mr. H. O. Forbes, who visited these islands in 1878, increased the
+number of wild plants to thirty-six, and these belonged to twenty-six
+natural orders.
+
+[115] Juan Fernandez is a good example of a small island which, with time
+and favourable conditions, has acquired a tolerably rich and highly
+peculiar flora and fauna. It is situated in 34° S. Lat., 400 miles from the
+coast of Chile, and so far as facilities for the transport of living
+organisms are concerned is by no means in a favourable position, for the
+ocean-currents come from the south-west in a direction where there is no
+land but the Antarctic continent, and the prevalent winds are also
+westerly. No doubt, however, there are occasional storms, and there may
+have been intermediate islands, but its chief advantages are its antiquity,
+its varied surface, and its favourable soil and climate, offering many
+chances for the preservation and increase of whatever plants and animals
+have chanced to reach it. The island consists of basalt, greenstone, and
+other ancient rocks, and though only about twelve miles long its mountains
+are three thousand feet high. Enjoying a moist and temperate climate it is
+especially adapted to the growth of ferns, which are very abundant; and as
+the spores of these plants are as fine as dust, and very easily carried for
+enormous distances by winds, it is not surprising that there are nearly
+fifty species on the island, while the remote period when it first received
+its vegetation may be indicated by the fact that nearly half the species
+are quite peculiar; while of 102 species of flowering plants seventy are
+peculiar, and there are ten peculiar genera. The same general character
+pervades the fauna. For so small an island it is rich, containing four true
+land-birds, about fifty species of insects, and twenty of land-shells.
+Almost all these belong to South American genera, and a large proportion
+are South American species; but several of the insects, half the birds, and
+the whole of the land-shells are peculiar. This seems to indicate that the
+means of transmission were formerly greater than they are now, and that in
+the case of land-shells none have been introduced for so long a period that
+all have become modified into distinct forms, or have been preserved on the
+island while they have become extinct on the continent. For a detailed
+examination of the causes which have led to the modification of the humming
+birds of Juan Fernandez see the chapter on Humming Birds in the author's
+_Natural Selection and Tropical Nature_, p. 324; while a general account of
+the fauna of the island is given in his _Geographical Distribution of
+Animals_, Vol. II. p. 49.
+
+[116] No additions appear to have been made to this flora down to 1885,
+when Mr. Hemsley published his _Report on the Present State of our
+Knowledge of Insular Floras_.
+
+[117] _Journal of the Linnean Society_, Vol. XIII., "Botany," p. 556.
+
+[118] _Geographical Distribution of Animals_, Vol. II. p. 81.
+
+[119] _St. Helena: a Physical, Historical, and Topographical Description of
+the Island, &c._ By John Charles Melliss, F.G.S., &c. London: 1875.
+
+[120] Mr. Marsh in his interesting work entitled _The Earth as Modified by
+Human Action_ (p. 51), thus remarks on the effect of browsing quadrupeds in
+destroying and checking woody vegetation.--"I am convinced that forests
+would soon cover many parts of the Arabian and African deserts if man and
+domestic animals, especially the goat and the camel, were banished from
+them. The hard palate and tongue, and strong teeth and jaws of this latter
+quadruped enable him to break off and masticate tough and thorny branches
+as large as the finger. He is particularly fond of the smaller twigs,
+leaves, and seed-pods of the _Sont_ and other acacias, which, like the
+American robinia, thrive well on dry and sandy soils, and he spares no tree
+the branches of which are within his reach, except, if I remember right,
+the tamarisk that produces manna. Young trees sprout plentifully around the
+springs and along the winter water-courses of the desert, and these are
+just the halting stations of the caravans and their routes of travel. In
+the shade of these trees annual grasses and perennial shrubs shoot up, but
+are mown down by the hungry cattle of the Bedouin as fast as they grow. A
+few years of undisturbed vegetation would suffice to cover such points with
+groves, and these would gradually extend themselves over soils where now
+scarcely any green thing but the bitter colocynth and the poisonous
+foxglove is ever seen."
+
+[121] _Coleoptera Sanctæ Helenæ_, 1877; _Testacea Atlantica_, 1878.
+
+[122] On Petermann's map of Africa, in _Stieler's Hand-Atlas_ (1879), the
+Island of Ascension is shown as seated on a much larger and shallower
+submarine bank than St. Helena. The 1,000 fathom line round Ascension
+encloses an oval space 170 miles long by 70 wide, and even the 300 fathom
+line, one over 60 miles long; and it is therefore probable that a much
+larger island once occupied this site. Now Ascension is nearly equidistant
+between St. Helena and Liberia, and such an island might have served as an
+intermediate station through which many of the immigrants to St. Helena
+passed. As the distances are hardly greater than in the case of the Azores,
+this removes whatever difficulty may have been felt of the possibility of
+_any_ organisms reaching so remote an island. The present island of
+Ascension is probably only the summit of a huge volcanic mass, and any
+remnant of the original fauna and flora it might have preserved may have
+been destroyed by great volcanic eruptions. Mr. Darwin collected some
+masses of tufa which were found to be mainly organic, containing, besides
+remains of fresh-water infusoria, the siliceous tissue of plants! In the
+light of the great extent of the submarine bank on which the island stands,
+Mr. Darwin's remark, that--"we may feel sure, that at some former epoch,
+the climate and productions of Ascension were very different from what they
+are now,"--has received a striking confirmation. (See _Naturalist's Voyage
+Round the World_, p. 495.)
+
+[123] "Notes on the Classification, History, and Geographical Distribution
+of Compositæ."--_Journal of the Linnean Society_, Vol. XIII. p. 563 (1873).
+
+[124] The Melhaniæ comprise the two finest timber trees of St. Helena, now
+almost extinct, the redwood and native ebony.
+
+[125] _Journal of the Linnean Society_, 1873, p. 496. "On Diversity of
+Evolution under one set of External Conditions." _Proceedings of the
+Zoological Society of London_, 1873, p. 80. "On the Classification of the
+Achitinellidæ."
+
+[126] "Memoirs on the Coleoptera of the Hawaiian Islands." By the Rev. T.
+Blackburn, B.A., and Dr. D. Sharp. _Scientific Transactions of the Royal
+Dublin Society._ Vol. III. Series II. 1885.
+
+[127] See Hildebrand's _Flora of the Hawaiian Islands_, Introduction, p.
+xiv.
+
+[128] _Flora of the Hawaiian Islands_, by W. Hildebrand, M.D., annotated
+and published after the author's death by W. F. Hildebrand, 1888.
+
+[129] These are obtained from Hildebrand's _Flora_ supplemented by Mr.
+Bentham's paper in the _Journal of the Linnean Society_.
+
+[130] Among the curious features of the Hawaiian flora is the extraordinary
+development of what are usually herbaceous plants into shrubs or trees.
+Three species of Viola are shrubs from three to five feet high. A shrubby
+Silene is nearly as tall; and an allied endemic genus, Schiedea, has
+numerous shrubby species. _Geranium arboreum_ is sometimes twelve feet
+high. The endemic Compositæ are mostly shrubs, while several are trees
+reaching twenty or thirty feet in height. The numerous Lobeliaceæ, all
+endemic, are mostly shrubs or trees, often resembling palms or yuccas in
+habit, and sometimes twenty-five or thirty feet high. The only native genus
+of Primulaceæ--Lysimachia--consists mainly of shrubs; and even a plantain
+has a woody stem sometimes six feet high.
+
+[131] _Geological Magazine_, 1870, p. 155.
+
+[132] _Transactions of the Edinburgh Geological Society_, Vol. I. p. 330.
+
+[133] _Quarterly Journal of Geological Society_, 1850, p. 96.
+
+[134] _British Association Report_, Dundee, 1867, p. 431.
+
+[135] The list of names was furnished to me by Dr. Günther, and I have
+added the localities from the papers containing the original descriptions,
+and from Dr. Haughton's _British Freshwater Fishes_.
+
+[136] See "The Virginia Colony of Helix nemoralis," T. D. A. Cockerell, in
+_The Nautilus_, Vol. III. No. 7, p. 73.
+
+[137] I am indebted to Mr. Mitten for this curious fact.
+
+[138] The following remarks by Dr. Richard Spruce, who has made a special
+study of mosses and especially of hepaticæ, are of interest. "From what
+precedes, I conclude that no existing agency is capable of transporting the
+germs of our hepatics of tropical type from the torrid zone to Britain, and
+I venture to suppose that their existence at Killarney dates from the
+remote period when the vegetation of the whole northern hemisphere partook
+of a tropical character. If I am challenged to account for their survival
+through the last glacial period, I reply that, granting even the existence
+of a universal ice-cap down to the latitude of 40° in America and 50° in
+Europe, it is not to be assumed that the whole extent, even of land, was
+_perennially_ entombed 'in thrilling regions of thick-ribbed ice.' Towards
+the southern margin of the ice the climate was probably very similar to
+that of Greenland and the northern part of Norway at the present day. The
+summer sun would have great power, and on the borders of sheltered fjords
+the frozen snow would disappear completely, if only for a very short
+period, and I ask only for a month or two, not doubting the capacity of our
+hepatics to survive in a dormant state under the snow for at least ten
+months in the year. I have gathered mosses in the Pyrenees where the snow
+had barely left them on August 2nd; by September 25th they were re-covered
+with snow, and would not be again uncovered till the following year. The
+mosses of Killarney might even enjoy a longer summer than this; for the
+gulf-stream laves both sides of the south-western angle of Ireland, and its
+tepid waters would exert great melting power on the ice-bound coast,
+preventing at the same time any formation of ice in the sea itself." This
+passage is the conclusion of a very interesting discussion on the
+distribution of hepaticæ in a paper on "A New Hepatic from Killarney," in
+the _Journal of Botany_, vol. 25, (Feb. 1887), pp. 33-82, in which many
+curious facts are given as to the habits and distribution of these curious
+and beautiful little plants.
+
+[139] While these pages are passing through the press I am informed by my
+friend Mr. W. H. Beeby that in the Shetland Isles, where he has been
+collecting for five summers, he has found several plants new to the British
+flora, and a few altogether undescribed. Among these latter is a very
+distinct species of Hieracium (_H. Zetlandicum_), which is quite unknown in
+Scandinavia, and is almost certainly peculiar to the British Islands. Here
+we have another proof that entirely new species are still to be discovered
+in the remoter portions of our country.
+
+[140] In the first edition of this work the numbers were 400 and 340,
+showing the great increase of our knowledge during the last ten years,
+chiefly owing to the researches of Mr. A. H. Everett in Sarawak and Mr.
+John Whitehead in North Borneo and the great mountain Kini Balu.
+
+[141] These are Allocotops, Chlorocharis, Androphilus, and Ptilopyga, among
+the Timeliidæ; Tricophoropsis and Oreoctistes among the Brachypodidæ;
+Chlamydochoera among the Campophagidæ.
+
+[142] In a letter from Darwin he says:--"Hooker writes to me, 'Miguel has
+been telling me that the flora of Sumatra and Borneo are identical, and
+that of Java quite different.'"
+
+[143] "On the Geology of Sumatra," by M. R. D. M. Verbeck. _Geological
+Magazine_, 1877.
+
+[144] _Pitta megarhynchus_ (Banca) allied to _P. brachyurus_ (Borneo,
+Sumatra, Malacca); and _Pitta bangkanus_ (Banca) allied to _P. sordidus_
+(Borneo and Sumatra).
+
+[145] The following list of the mammalia of the Philippines and the Sulu
+Islands has been kindly furnished me by Mr. Everett.
+
+ QUADRUMANA.
+
+ 1. Macacus cynomolgus.
+ 2. Tarsius spectrum.
+
+ CARNIVORA.
+
+ 3. Viverra tangalunga.
+ 4. Paradoxurus philippinensis. Also in Palawan.
+ 5. Felis bengalensis. In Negros Island.
+
+ UNGULATA.
+
+ 6. Bubalus mindorensis. Peculiar species.
+ 7. Cervus philippinus. Peculiar species.
+ 8. " alfredi. Peculiar species.
+ 9. " nigricans. Peculiar species.
+ 10. " pseudaxis. Sulu only. Probably introduced.
+ 11. Sus marchesi. Peculiar species.
+
+ RODENTIA.
+
+ 12. Sciurus philippinensis. Peculiar species.
+ 13. Sciurus cagos. Peculiar species.
+ 14. " concinnus. Peculiar. Mindanao and Basilan.
+ 15. Phlæomys cummingi. Peculiar genus.
+ 16. Mus ephippium.
+ 17. " everetti. Peculiar species.
+
+ INSECTIVORA.
+
+ 18. Crocidura luzoniensis. Peculiar species.
+ 19. Crocidura edwardsiana. Peculiar species.
+ 20. Dendrogale sp.
+ 21. Galeopithecus philippinensis. Peculiar species.
+
+ CHIROPTERA.
+
+ 22. Pteropus leucopterus.
+ 23. " edulis.
+ 24. " hypomelanus.
+ 25. " jubatus.
+ 26. Xantharpyia amplexicaule.
+ 27. Cynopterus marginatus.
+ 28. " jagorii. Peculiar species.
+ 29. Carponycteris australis.
+ 30. Rhinolophus luctus.
+ 31. " philippinensis. Peculiar species.
+ 32. Rhinolophus rufus. Peculiar species.
+ 33. Hipposideros diadema.
+ 34. " pygmæus. Peculiar species.
+ 35. Hipposideros larvatus.
+ 36. " obscurus. Peculiar species.
+ 37. Hipposideros coronatus. Peculiar species.
+ 38. Hipposideros bicolor.
+ 39. Megaderma spasma.
+ 40. Vesperugo pachypus.
+ 41. " tenuis.
+ 42. Vesperugo abramus.
+ 43. Nycticejus kuhlii.
+ 44. Vespertilio macrotarsus. Peculiar species.
+ 45. Vespertilio capaccinii.
+ 46. Harpiocephalus cyclotis.
+ 47. Kerivoula hardwickii.
+ 48. Kerivoula pellucida. Peculiar species.
+ 49. " jagorii. Peculiar species.
+ 50. Miniopterus schreibersii.
+ 51. " tristis. Peculiar species.
+ 52. Emballonura monticola.
+ 53. Taphyzous melanopogon.
+ 54. Nyctinomus plicatus.
+
+[146] Extracted from Messrs. Blakiston and Pryer's _Catalogue of Birds of
+Japan_ (_Ibis_, 1878, p. 209), with Mr. Seebohm's additions and corrections
+in his _Birds of the Japanese Empire_ 1890. Accidental stragglers are not
+reckoned as British birds.
+
+[147] Mr. Swinhoe died in October, 1877, at the early age of forty-two. His
+writings on natural history are chiefly scattered through the volumes of
+the _Proceedings of the Zoological Society_ and _The Ibis_; the whole being
+summarised in his _Catalogue of the Mammals of South China and Formosa_
+(_P. Z. S._, 1870, p. 615), and his _Catalogue of the Birds of China and
+its Islands_ (_P. Z. S._, 1871, p. 337).
+
+[148] Captain Blakiston has shown that the northern island--Yezo--is much
+more temperate and less peculiar in its zoology than the central and
+southern islands. This is no doubt dependent chiefly on the considerable
+change of climate that occurs on passing the Tsu-garu strait.
+
+[149] See Dr. J. E. Gray's "Revision of the Viverridæ," in _Proc. Zool.
+Soc._ 1864, p. 507.
+
+[150] Some of the Bats of Madagascar and East Africa are said to have their
+nearest allies in Australia. (See Dobson in _Nature_, Vol. XXX. p. 575.)
+
+[151] This view was, I believe, first advanced by Professor Huxley in his
+"Anniversary Address to the Geological Society," in 1870. He says:--"In
+fact the Miocene mammalian fauna of Europe and the Himalayan regions
+contain, associated together, the types which are at present separately
+located in the South African and Indian provinces of Arctogæa. Now there is
+every reason to believe, on other grounds, that both Hindostan south of the
+Ganges, and Africa south of the Sahara, were separated by a wide sea from
+Europe and North Asia during the Middle and Upper Eocene epochs. Hence it
+becomes highly probable that the well-known similarities, and no less
+remarkable differences, between the present faunæ of India and South Africa
+have arisen in some such fashion as the following: Some time during the
+Miocene epoch, the bottom of the nummulitic sea was upheaved and converted
+into dry land in the direction of a line extending from Abyssinia to the
+mouth of the Ganges. By this means the Dekkan on the one hand and South
+Africa on the other, became connected with the Miocene dry land and with
+one another. The Miocene mammals spread gradually over this intermediate
+dry land; and if the condition of its eastern and western ends offered as
+wide contrasts as the valleys of the Ganges and Arabia do now, many forms
+which made their way into Africa must have been different from those which
+reached the Dekkan, while others might pass into both these sub-provinces."
+
+This question is fully discussed in my _Geographical Distribution of
+Animals_ (Vol. I., p. 285), where I expressed views somewhat different from
+those of Professor Huxley, and made some slight errors which are corrected
+in the present work. As I did not then refer to Professor Huxley's prior
+statement of the theory of Miocene immigration into Africa (which I had
+read but the reference to which I could not recall) I am happy to give his
+views here.
+
+[152] The total number of Madagascar birds is 238, of which 129 are
+absolutely peculiar to the island, as are thirty-five of the genera. All
+the peculiar birds but two are land birds. These are the numbers given in
+M. Grandidier's great work on Madagascar.
+
+[153] _The Ibis_, 1877, p. 334.
+
+[154] In a paper read before the Geological Society in 1874, Mr. H. F.
+Blanford, from the similarity of the fossil plants and reptiles, supposed
+that India and South Africa had been connected by a continent, "and
+remained so connected with some short intervals from the Permian up to the
+end of the Miocene period," and Mr. Woodward expressed his satisfaction
+with "this further evidence derived from the fossil flora of the Mesozoic
+series of India in corroboration of the former existence of an old
+submerged continent--Lemuria."
+
+Those who have read the preceding chapters of the present work will not
+need to have pointed out to them how utterly inconclusive is the
+fragmentary evidence derived from such remote periods (even if there were
+no evidence on the other side) as indicating geographical changes. The
+notion that a similarity in the productions of widely separated continents
+at any past epoch is only to be explained by the existence of a _direct_
+land-connection, is entirely opposed to all that we know of the wide and
+varying distribution of _all_ types at different periods, as well as to the
+great powers of dispersal over moderate widths of ocean possessed by all
+animals except mammalia. It is no less opposed to what is now known of the
+general permanency of the great continental and oceanic areas; while in
+this particular case it is totally inconsistent (as has been shown above)
+with the actual facts of the distribution of animals.
+
+[155] _Geographical Distribution of Animals_, Vol. I., pp. 272-292.
+
+[156] The term "Mascarene" is used here in an extended sense, to include
+all the islands near Madagascar which resemble it in their animal and
+vegetable productions.
+
+[157] For the birds of the Comoro Islands see _Proc. Zool. Soc._, 1877, p.
+295, and 1879, p. 673.
+
+[158] The following is a list of these peculiar birds. (See the _Ibis_, for
+1867, p. 359; and 1879, p. 97.)
+
+ PASSERES.
+
+ _Ellisia seychelensis._
+ _Copsychus seychellarum._
+ _Hypsipetes crassirostris._
+ _Tchitrea corvina._
+ _Nectarinia dussumieri._
+ _Zosterops modesta._
+ " _semiflava._
+ _Foudia seychellarum._
+
+ PSITTACI.
+
+ _Coracopsis barklyi._
+ _Palæornis wardi._
+
+ COLUMBÆ.
+
+ _Alectorænas pulcherrimus._
+ _Turtur rostratus._
+
+ ACCIPITRES.
+
+ _Tinnunculus gracilis._
+
+[159] Specimens are recorded from West Africa in the _Proceedings of the
+Academy of Natural Science_, Philadelphia, 1857, p. 72, while specimens in
+the Paris Museum were brought by D'Orbigny from S. America. Dr. Wright's
+specimens from the Seychelles have, as he informs me, been determined to be
+the same species by Dr. Peters of Berlin.
+
+[160] "Additional Notes on the Land-shells of the Seychelles Islands." By
+Geoffrey Nevill, C.M.Z.S. _Proc. Zool. Soc._ 1869, p. 61.
+
+[161] In Maillard's _Notes sur l'Isle de Réunion_, a considerable number of
+mammalia are given as "wild," such as _Lemur mongoz_ and _Centetes
+setosus_, both Madagascar species, with such undoubtedly introduced animals
+as a wild cat, a hare, and several rats and mice. He also gives two species
+of frogs, seven lizards, and two snakes. The latter are both Indian species
+and certainly imported, as are most probably the frogs. Legouat, who
+resided some years in the island nearly two centuries ago, and who was a
+closer observer of nature, mentions numerous birds, large bats,
+land-tortoises, and lizards, but no other reptiles or venomous animals
+except scorpions. We may be pretty sure, therefore, that the land-mammalia,
+snakes, and frogs, now found wild, have all been introduced. Of lizards, on
+the other hand, there are several species, some peculiar to the island,
+others common to Africa and the other Mascarene Islands. The following list
+by Prof. Dumeril is given in Maillard's work:--
+
+ _Platydactylus cepedianus._
+ " _ocellatus._
+ _Hemidactylus peronii._
+ " _mutilatus._
+ _Hemidactylus frenatus._
+ _Gongylus bojerii._
+ _Ablepharus peronii._
+
+Four species of chameleon are now recorded from Bourbon and one from
+Mauritius (J. Reay Greene, M.D., in _Pop. Science Rev._ April, 1880), but
+as they are not mentioned by the old writers, it is pretty certain that
+these creatures are recent introductions, and this is the more probable as
+they are favourite domestic pets.
+
+Darwin informed me that in a work entitled _Voyage à l'Isle de France, par
+un Officier du Roi_, published in 1770, it is stated that a fresh-water
+fish had been introduced from Batavia and had multiplied. The writer also
+says (p. 170): "_On a essayé, mais sans succcès, d'y transporter des
+grenouilles qui mangent les oeufs que les moustigues deposent sur les eaux
+stagnantes._" It thus appears that there were then no frogs on the island.
+
+[162] That the dodo is really an abortion from a more perfect type, and not
+a direct development from some lower form of wingless bird, is shown by its
+possessing a keeled sternum, though the keel is exceedingly reduced, being
+only three-quarters of an inch deep in a length of seven inches. The most
+terrestrial pigeon--the Didunculus of the Samoan Islands, has a far deeper
+and better developed keel, showing that in the case of the dodo the
+degradation has been extreme. We have also analogous examples in other
+extinct birds of the same group of islands, such as the flightless
+Rails--Aphanapteryx of Mauritius and Erythromachus of Rodriguez, as well as
+the large parrot--Lophopsittacus of Mauritius, and the Night Heron,
+_Nycticorax megacephala_ of Rodriguez, the last two birds probably having
+been able to fly a little. The commencement of the same process is to be
+seen in the peculiar dove of the Seychelles, _Turtur rostratus_, which, as
+Mr. Edward Newton has shown, has much shorter wings than its close ally,
+_T. picturatus_, of Madagascar. For a full and interesting account of these
+and other recently extinct birds see Professor Newton's article on "Fossil
+Birds" in the _Encyclopædia Britannica_, ninth edition, vol. iii., p. 732;
+and that on "The Extinct Birds of Rodriguez," by Dr. A. Günther and Mr. E.
+Newton, in the Royal Society's volume on the Transit of Venus Expedition.
+
+[163] See _Ibis_, 1877, p. 334.
+
+[164] A common Indian and Malayan toad (_Bufo melanostictus_) has been
+introduced into Mauritius and also some European toads, as I am informed by
+Dr. Günther.
+
+[165] This brief account of the Madagascar flora has been taken from a very
+interesting paper by the Rev. Richard Baron, F.L.S., F.G.S., in the
+_Journal of the Linnean Society_, Vol. XXV., p. 246; where much information
+is given on the distribution of the flora within the island.
+
+[166] It may be interesting to botanists and to students of geographical
+distribution to give here an enumeration of the endemic genera of the
+_Flora of the Mauritius and the Seychelles_, as they are nowhere separately
+tabulated in that work.
+
+ Aphloia (Bixaceæ) 1 sp., a shrub, Maur., Rod., Sey., also
+ Madagascar.
+ Medusagyne (Ternströmiaceæ) 1 sp., a shrub, Seychelles.
+ Astiria (Sterculiaceæ) 1 sp., a shrub, Mauritius.
+ Quivisia (Meliaceæ) 3 sp., shrubs, Mauritius (2 sp.),
+ Rodriguez (1 sp.), also Bourbon.
+ Cossignya (Sapindaceæ) 1 sp., a shrub, Mauritius, also Bourbon.
+ Hornea ,, 1 sp., a shrub, Mauritius.
+ Stadtmannia ,, 1 sp., a shrub, Mauritius.
+ Doratoxylon ,, 1 sp., a shrub, Mauritius and Bourbon.
+ Gagnebina (Leguminosæ) 1 sp., a shrub, Mauritius, also
+ Madagascar.
+ Roussea (Saxifragaceæ) 1 sp., a climbing shrub, Mauritius and
+ Bourbon.
+ Tetrataxis (Lythraceæ) 1 sp., a shrub, Mauritius.
+ Psiloxylon ,, 1 sp., a shrub, Mauritius and Bourbon.
+ Mathurina (Turneraceæ) 1 sp., a shrub, Rodriguez.
+ Foetidia (Myrtaceæ) 1 sp., a tree, Mauritius.
+ Danais (Rubiaceæ) 4 sp., climbing shrubs, Maur. (1 sp.),
+ Rodr. (1 sp.), also Bourbon and
+ Madagascar.
+ Fernelia (Rubiaceæ) 1 sp., a shrub, Mauritius and Rodriguez.
+ Pyrostria ,, 6 sp., shrubs, Mauritius (3 sp.), also
+ Bourbon and Madagascar.
+ Scyphochlamys (Rubiaceæ) 1 sp., a shrub, Rodriguez.
+ Myonima ,, 3 sp., shrubs, Mauritius, also Bourbon.
+ Cylindrocline (Compositæ) 1 sp., a shrub, Mauritius.
+ Monarrhenus ,, 2 sp., shrubs, Mauritius, also Bourbon
+ and Madagascar.
+ Faujasia (Compositæ) 3 sp., shrubs, Mauritius, also Bourbon
+ and Madagascar.
+ Heterochænia (Campanulaceæ) 1 sp., a shrub, Mauritius, also Bourbon.
+ Tanulepis (Asclepiadaceæ) 1 sp., a climber, Rodriguez.
+ Decanema ,, 1 sp., a climber, Mauritius, also
+ Madagascar.
+ Nicodemia (Loganiaceæ) 2 sp., shrubs, Mauritius (1 sp.), also
+ Comoro Islands and Madagascar.
+ Bryodes (Scrophulariaceæ) 1 sp., herb, Mauritius.
+ Radamæa ,, 2 sp., herb, Seychelles (1 sp.), and
+ Madagascar.
+ Colea (Bignoniaceæ) 10 sp., Mauritius (1 sp.), Seychelles (1
+ sp.), also Bourbon and Madagascar.
+ (Shrubs, trees, or climbers.)
+ Obetia (Urticaceæ) 2 sp., shrubs, Mauritius, Seychelles,
+ and Madagascar.
+ Bosquiea (Moreæ) 3 sp., trees, Seychelles (1 sp.), also
+ Madagascar.
+ Monimia (Monimiaceæ) 3 sp., trees, Mauritius (2 sp.), also
+ Bourbon.
+ Cynorchis (Orchideæ) 3 sp., herb, ter., Mauritius.
+ Amphorchis ,, 1 sp., herb, ter., Mauritius, also
+ Bourbon.
+ Arnottia ,, 2 sp., herb, ter., Mauritius, also
+ Bourbon.
+ Aplostellis ,, 1 sp., herb, ter., Mauritius.
+ Cryptopus ,, 1 sp., herb, Epiphyte, Mauritius, also
+ Bourbon and Madagascar.
+ Lomatophyllum (Liliaceæ) 3 sp., shrubs (succulent), Mauritius,
+ also Bourbon.
+ Lodoicea (Palmæ) 1 sp., tree, Seychelles.
+ Latania ,, 3 sp., trees, Mauritius (2 sp.),
+ Rodriguez, also Bourbon.
+ Hyophorbe ,, 3 sp., trees, Mauritius (2 sp.),
+ Rodriguez, also Bourbon.
+ Dictyosperma ,, 1 sp., tree, Mauritius, Rodriguez,
+ also Bourbon.
+ Acanthophænix ,, 2 sp., trees, Mauritius, also Bourbon.
+ Deckenia ,, 1 sp., tree, Seychelles.
+ Nephrosperma ,, 1 sp., tree, Seychelles.
+ Roscheria ,, 1 sp., tree, Seychelles.
+ Verschaffeltia ,, 1 sp., tree, Seychelles.
+ Stevensonia ,, 1 sp., tree, Seychelles.
+ Ochropteris (Filices) 1 sp., herb, Mauritius, also Bourbon and
+ Madagascar.
+
+Among the curious features in this list are the great number of endemic
+shrubs in Mauritius, and the remarkable assemblage of five endemic genera
+of palms in the Seychelles Islands. We may also notice that one palm
+(_Latania loddigesii_) is confined to Round Island and two other adjacent
+islets offering a singular analogy to the peculiar snake also found there.
+
+[167]
+
+_Families of Malayan Birds not found in islands East of Celebes._
+
+ Troglodytidæ.
+ Sittidæ.
+ Paridæ.
+ Liotrichidæ.
+ Phyllornithidæ.
+ Eurylæmidæ.
+ Picidæ.
+ Indicatoridæ.
+ Megalænidæ.
+ Trogonidæ.
+ Phasianidæ.
+
+_Families of Moluccan Birds not found in islands West of Celebes._
+
+ Paradiseidæ.
+ Meliphagidæ.
+ Cacatuidæ.
+ Platycercidæ.
+ Trichoglossidæ.
+ Nestoridæ.
+
+[168] For outline figures of the chief types of these butterflies, see my
+_Malay Archipelago_, Vol. I. p. 441, or p. 216 of the tenth edition.
+
+[169] Dobson on the Classification of Chiroptera (_Ann. and Mag. of Nat.
+Hist._ Nov. 1875).
+
+[170] See Buller, "On the New Zealand Rat," _Trans. of the N. Z. Institute_
+(1870), Vol. III. p. 1, and Vol. IX. p. 348; and Hutton, "On the
+Geographical Relations of the New Zealand Fauna," _Trans. N. Z. Instit._
+1872, p. 229.
+
+[171] Hochstetter's _New Zealand_, p. 161, note.
+
+[172] The animal described by Captain Cook as having been seen at
+Pickersgill Harbour in Dusky Bay (Cook's 2nd Voyage, Vol. I. p. 98) may
+have been the same creature. He says, "A four-footed animal was seen by
+three or four of our people, but as no two gave the same description of it,
+I cannot say what kind it is. All, however, agreed that it was about the
+size of a cat, with short legs, and of a mouse colour. One of the seamen,
+and he who had the best view of it, said it had a bushy tail, and was the
+most like a jackal of any animal he knew." It is suggestive that, so far as
+the points on which "all agreed"--the size and the dark colour--this
+description would answer well to the animal so recently seen, while the
+"short legs" correspond to the otter-like tracks, and the thick tail of an
+otter-like animal may well have appeared "bushy" when the fur was dry. It
+has been suggested that it was only one of the native dogs; but as none of
+those who saw it took it for a dog, and the points on which they all agreed
+are not dog-like, we can hardly accept this explanation; while the actual
+existence of an unknown animal in New Zealand of corresponding size and
+colour is confirmed by this account of a similar animal having been seen
+about a century ago.
+
+[173] Owen, "On the Genus Dinornis," _Trans. Zool. Soc._ Vol. X. p. 184.
+Mivart, "On the Axial Skeleton of the Struthionidæ," _Trans. Zool. Soc._
+Vol. X. p. 51.
+
+[174] The recent existence of the Moa and its having been exterminated by
+the Maoris appears to be at length set at rest by the statement of Mr. John
+White, a gentleman who has been collecting materials for a history of the
+natives for thirty-five years, who has been initiated by their priests into
+all their mysteries, and is said to "know more about the history, habits,
+and customs of the Maoris than they do themselves." His information on this
+subject was obtained from old natives long before the controversy on the
+subject arose. He says that the histories and songs of the Maoris abound in
+allusions to the Moa, and that they were able to give full accounts of "its
+habits, food, the season of the year it was killed, its appearance,
+strength, and all the numerous ceremonies which were enacted by the natives
+before they began the hunt, the mode of hunting, how cut up, how cooked,
+and what wood was used in the cooking, with an account of its nest, and how
+the nest was made, where it usually lived, &c." Two pages are occupied by
+these details, but they are only given from memory, and Mr. White promises
+a full account from his MSS. Many of the details given correspond with
+facts ascertained from the discovery of native cooking places with Moas'
+bones; and it seems quite incredible that such an elaborate and detailed
+account should be all invention. (See _Transactions of the New Zealand
+Institute_, Vol. VIII. p. 79.)
+
+[175] See fig. in _Trans. of N. Z. Institute_, Vol. III., plate 12_b._ fig.
+2.
+
+[176] _Geographical Distribution of Animals_, Vol. I., p. 450.
+
+[177] In my _Geographical Distribution of Animals_ (I. p. 541) I have given
+two peculiar Australian genera (_Orthonyx_ and _Tribonyx_) as occurring in
+New Zealand. But the former has been found in New Guinea, while the New
+Zealand bird is considered to form a distinct genus, _Clitonyx_; and the
+latter inhabits Tasmania, and was recorded from New Zealand through an
+error. (See _Ibis_, 1873, p. 427.)
+
+[178] The peculiar genera of Australian lizards according to Boulenger's
+British Museum Catalogue, are as follows:--Family GECKONIDÆ: Nephrurus,
+Rhynchoedura, Heteronota, Diplodactylus, Oedura. Family PYGOPODIDÆ
+(peculiar): Pygopus, Cryptodelma, Delma, Pletholax, Aprasia. Family
+AGAMIDÆ: Chelosania, Amphibolurus, Tympanocryptis, Diporophora,
+Chlamydosaurus, Moloch, Oreodeira. Family SCINCIDÆ: Egerina, Trachysaurus,
+Hemisphænodon. Family doubtful: Ophiopsiseps.
+
+[179] These figures are taken from Mr. G. M. Thomson's address "On the
+Origin of the New Zealand Flora," _Trans. N. Z. Institute_, XIV. (1881),
+being the latest that I can obtain. They differ somewhat from those given
+in the first edition, but not so as to affect the conclusions drawn from
+them.
+
+[180] This accords with the general scarcity of Leguminosæ in Oceanic
+Islands, due probably to their usually dry and heavy seeds, not adapted to
+any of the forms of aërial transmission; and it would indicate either that
+New Zealand was never absolutely united with Australia, or that the union
+was at a very remote period when Leguminosæ were either not differentiated
+or comparatively rare.
+
+[181] Sir Joseph Hooker informs me that the number of tropical Australian
+plants discovered within the last twenty years is very great, and that the
+statement as above made may have to be modified. Looking, however, at the
+enormous disproportion of the figures given in the "Introductory Essay" in
+1859 (2,200 tropical to 5,800 temperate species) it seems hardly possible
+that a great difference should not still exist, at all events as regards
+species. In Baron von Müeller's latest summary of the Australian Flora
+(_Second Systematic Census of Australian Plants_, 1889), he gives the total
+species at 8,839, of which 3,560 occur in West Australia, and 3,251 in New
+South Wales. On counting the species common to these two colonies in fifty
+pages of the _Census_ taken at random, I find them to be about one-tenth of
+the total species in both. This would give the number of distinct species
+in these areas as about 6,130. Adding to these the species peculiar to
+Victoria and South Australia, we shall have a flora of near 6,500 in the
+temperate parts of Australia. It is true that West Australia extends far
+into the tropics, but an overwhelming majority of the species have been
+discovered in the south-western portion of the colony, while the species
+that may be exclusively tropical will be more than balanced by those of
+temperate Queensland, which have not been taken account of, as that colony
+is half temperate and half tropical. It thus appears probable that full
+three fourths of the species of Australian plants occur in the temperate
+regions, and are mainly characteristic of it. Sir Joseph Hooker also doubts
+the generally greater richness of tropical over temperate floras which I
+have taken as almost an axiom. He says: "Taking similar areas to Australia
+in the Western World, _e.g._, tropical Africa north of 20° S. Lat. as
+against temperate Africa and Europe up to 47°--I suspect that the latter
+would present more genera and species than the former." This, however,
+appears to me to be hardly a case in point, because Europe is a distinct
+continent from Africa and has had a very different past history, and it is
+not a fair comparison to take the tropical area in one continent while the
+temperate is made up of widely separated areas in two continents. A closer
+parallel may perhaps be found in equal areas of Brazil and south temperate
+America, or of Mexico and the Southern United States, in both of which
+cases I suppose there can be little doubt that the tropical areas are far
+the richest. Temperate South Africa is, no doubt, always quoted as richer
+than an equal area of tropical Africa or perhaps than any part of the world
+of equal extent, but this is admitted to be an exceptional case.
+
+[182] Sir Joseph Hooker thinks that later discoveries in the Australian
+Alps and other parts of East and South Australia may have greatly modified
+or perhaps reversed the above estimate, and the figures given in the
+preceding note indicate that this is so. But still, the small area of
+South-west Australia will be, proportionally, far the richer of the two. It
+is much to be desired that the enormous mass of facts contained in Mr.
+Bentham's _Flora Australiensis_ and Baron von Müeller's _Census_ should be
+tabulated and compared by some competent botanist, so as to exhibit the
+various relations of its wonderful vegetation in the same manner as was
+done by Sir Joseph Hooker with the materials available twenty-one years
+ago.
+
+[183] From an examination of the fossil corals of the South-west of
+Victoria, Professor P. M. Duncan concludes--"that, at the time of the
+formation of these deposits the central area of Australia was occupied by
+sea, having open water to the north, with reefs in the neighbourhood of
+Java." The age of these fossils is not known, but as almost all are extinct
+species, and some are almost identical with European Pliocene and Miocene
+species, they are supposed to belong to a corresponding period. (_Journal
+of Geol. Soc._, 1870.)
+
+[184] "On the Origin of the Fauna and Flora of New Zealand," by Captain
+F. W. Hutton, in _Annals and Mag. of Nat. Hist._ Fifth series, p. 427
+(June, 1884).
+
+[185] To these must now be added the genera Sequoia, Myrica, Aralia, and
+Acer, described by Baron von Ettingshausen. (_Trans. N.Z. Institute_, xix.,
+p. 449.)
+
+[186] The large collection of fossil plants from the Tertiary beds of New
+Zealand which have been recently described by Baron von Ettingshausen
+(_Trans. N. Z. Inst._, vol. xxiii., pp. 237-310), prove that a change in
+the vegetation has occurred similar to that which has taken place in
+Eastern Australia, and that the plants of the two countries once resembled
+each other more than they do now. We have, first, a series of groups now
+living in Australia, but which have become extinct in New Zealand, as
+Cassia, Dalbergia, Eucalyptus, Diospyros, Dryandra, Casuarina, and Ficus;
+and also such northern genera as Acer, Planera, Ulmus, Quercus, Alnus,
+Myrica, and Sequoia. All these latter, except Ulmus and Planera, have been
+found also in the Eastern-Australian Tertiaries, and we may therefore
+consider that at this period the northern temperate element in both floras
+was identical. If this flora entered both countries from the south, and was
+really Antarctic, its extinction in New Zealand may have been due to the
+submergence of the country to the south, and its elevation and extension
+towards the tropics, admitting of the incursion of the large number of
+Polynesian and tropical Australian types now found there; while the
+Australian portion of the same flora may have succumbed at a somewhat later
+period, when the elevation of the Cretaceous and Tertiary sea united it
+with Western Australia, and allowed the rich typical Australian flora to
+overrun the country. Of course we are assuming that the identification of
+these genera is for the most part correct, though almost entirely founded
+on leaves only. Fuller knowledge, both of the extinct flora itself and of
+the geological age of the several deposits, is requisite before any
+trustworthy explanation of the phenomena can be arrived at.
+
+[187] The following are the tropical genera common to New Zealand and
+Australia:--
+
+ 1. _Melicope._ Queensland, Pacific Islands.
+ 2. _Eugenia._ Eastern and Tropical Australia, Asia, and America.
+ 3. _Passiflora._ N.S.W. and Queensland, Tropics of Old World and America.
+ 4. _Myrsine._ Tropical and Temperate Australia, Tropical and Sub-tropical
+ regions.
+ 5. _Sapota._ Australia, Norfolk Islands, Tropics.
+ 6. _Cyathodes._ Australia and Pacific Islands.
+ 7. _Parsonsia._ Tropical Australia and Asia.
+ 8. _Geniostoma._ Queensland, Polynesia, Asia.
+ 9. _Mitrasacme._ Tropical and Temperate Australia, India.
+ 10. _Ipomoea._ Tropical Australia, Tropics.
+ 11. _Mazus._ Temperate Australia, India, China.
+ 12. _Vitex._ Tropical Australia, Tropical and Sub-tropical.
+ 13. _Pisonia._ Tropical Australia, Tropical and Sub-tropical.
+ 14. _Alternanthera._ Tropical Australia, India, and S. America.
+ 15. _Tetranthera._ Tropical Australia, Tropics.
+ 16. _Santalum._ Tropical and Sub-tropical Australia, Pacific, Malay
+ Islands.
+ 17. _Carumbium._ Tropical and Sub-tropical Australia, Pacific Islands.
+ 18. _Elatostemma._ Sub-tropical Australia, Asia, Pacific Islands.
+ 19. _Peperomia._ Tropical and Sub-tropical Australia, Tropics.
+ 20. _Piper._ Tropical and Sub-tropical Australia, Tropics.
+ 21. _Dacrydium._ Tasmania, Malay, and Pacific Islands.
+ 22. _Dammara._ Tropical Australia, Malay, and Pacific Islands.
+ 23. _Dendrobium._ Tropical Australia, Eastern Tropics.
+ 24. _Bolbophyllum._ Tropical and Sub-tropical Australia, Tropics.
+ 25. _Sarcochilus._ Tropical and Sub-tropical Australia, Fiji, and Malay
+ Islands.
+ 26. _Freycinetia._ Tropical Australia, Tropical Asia.
+ 27. _Cordyline._ Tropical Australia, Pacific Islands.
+ 28. _Dianella._ Australia, India, Madagascar, Pacific Islands.
+ 29. _Cyperus._ Australia, Tropical regions mainly.
+ 30. _Fimbristylis._ Tropical Australia, Tropical regions.
+ 31. _Paspalum._ Tropical and Sub-tropical grasses.
+ 32. _Isachne._ Tropical and Sub-tropical grasses.
+ 33. _Sporobolus._ Tropical and Sub-tropical grasses.
+
+[188] Insects are tolerably abundant in the open mountain regions, but very
+scarce in the forests. Mr. Meyrick says that these are "strangely deficient
+in insects, the same species occurring throughout the islands;" and Mr.
+Pascoe remarked that "the forests of New Zealand were the most barren
+country, entomologically, he had ever visited." (_Proc. Ent. Soc._, 1883.
+p. xxix.)
+
+[189] Introductory Essay _On the Flora of Australia_, p. 130.
+
+[190] Hooker, _On the Flora of Australia_, p. 95.--H. C. Watson, in
+Godman's _Azores_, pp. 278-286.
+
+[191] As this is a point of great interest in its bearing on the dispersal
+of plants by means of mountain ranges, I have endeavoured to obtain a few
+illustrative facts:--
+
+1. Mr. William Mitten, of Hurstpierpoint, Sussex, informs me that when the
+London and Brighton railway was in progress in his neighbourhood,
+_Melilotus vulgaris_ made its appearance on the banks, remained for several
+years, and then altogether disappeared. Another case is that of _Diplotaxis
+muralis_, which formerly occurred only near the sea-coast of Sussex, and at
+Lewes; but since the railway was made has spread along it, and still
+maintains itself abundantly on the railway banks though rarely found
+anywhere else.
+
+2. A correspondent in Tasmania informs me that whenever the virgin forest
+is cleared in that island there invariably comes up a thick crop of a plant
+locally known as fire-weed--a species of Senecio, probably _S. Australis_.
+It never grows except where the fire has gone over the ground, and is
+unknown except in such places. My correspondent adds:--"This autumn I went
+back about thirty-five miles through a dense forest, along a track marked
+by some prospectors the year before, and in one spot where they had camped,
+and the fire had burnt the fallen logs, &c., there was a fine crop of
+'fire-weed.' All around for many miles was a forest of the largest trees
+and dense scrub." Here we have a case in which burnt soil and ashes favour
+the germination of a particular plant, whose seeds are easily carried by
+the wind, and it is not difficult to see how this peculiarity might favour
+the dispersal of the species for enormous distances, by enabling it
+temporarily to grow and produce seeds on burnt spots.
+
+3. In answer to an inquiry on this subject, Mr. H. C. Watson has been kind
+enough to send me a detailed account of the progress of vegetation on the
+railway banks and cuttings about Thames Ditton. This account is written
+from memory, but as Mr. Watson states that he took a great interest in
+watching the process year by year, there can be no reason to doubt the
+accuracy of his memory. I give a few extracts which bear especially on the
+subject we are discussing.
+
+"One rather remarkable biennial plant appeared early (the second year, as I
+recollect) and renewed itself either two or three years, namely, _Isatis
+tinctoria_--a species usually supposed, to be one of our introduced, but
+pretty well naturalised, plants. The nearest stations then or since known
+to me for this _Isatis_ are on chalk about Guildford, twenty miles distant.
+There were two or three plants of it at first, never more than half a
+dozen. Once since I saw a plant of _Isatis_ on the railway bank near
+Vauxhall.
+
+"Close by Ditton Station three species appeared which may be called
+interlopers. The biennial _Barbarea precox_, one of these, is the least
+remarkable, because it might have come as seed in the earth from some
+garden, or possibly in the Thames gravel (used as ballast). At first it
+increased to several plants, then became less numerous, and will soon, in
+all probability, become extinct, crowded out by other plants. The biennial
+_Petroselinum segetum_ was at first one very luxuriant plant on the slope
+of the embankment. It increased by seed into a dozen or a score, and is now
+nearly if not quite extinct. The third species is _Linaria purpurea_, not
+strictly a British plant, but one established in some places on old walls.
+A single root of it appeared on the chalk facing of the embankment by
+Ditton Station. It has remained there several years and grown into a
+vigorous specimen. Two or three smaller examples are now seen by it,
+doubtless sprung from some of the hundreds or thousands of seeds shed by
+the original one plant. The species is not included in Salmon and Brewer's
+_Flora of Surrey_.
+
+"The main line of the railway has introduced into Ditton parish the
+perennial _Arabis hirsuta_, likely to become a permanent inhabitant. The
+species is found on the chalk and greensand miles away from Thames Ditton;
+but neither in this parish nor in any adjacent parish, so far as known to
+myself or to the authors of the flora of the county, does it occur. Some
+years after the railway was made a single root of this _Arabis_ was
+observed in the brickwork of an arch by which the railway is carried over a
+public road. A year or two afterwards there were three or four plants. In
+some later year I laid some of the ripened seed-pods between the bricks in
+places where the mortar had partly crumbled out. Now there are several
+scores of specimens in the brickwork of the arch. It is presumable that the
+first seed may have been brought from Guildford. But how could it get on to
+the perpendicular face of the brickwork?
+
+"The Bee Orchis (_Ophrys apifera_), plentiful on some of the chalk lands in
+Surrey, is not a species of Thames Ditton, or (as I presume) of any
+adjacent parish. Thus, I was greatly surprised some years back to see about
+a hundred examples of it in flower in one clayey field either on the
+outskirts of Thames Ditton or just within the limits of the adjoining
+parish of Cobham. I had crossed this same field in a former year without
+observing the Ophrys there. And on finding it in the one field I closely
+searched the surrounding fields and copses, without finding it anywhere
+else. Gradually the plants became fewer and fewer in that one field, and
+some six or eight years after its first discovery there the species had
+quite disappeared again. I guessed it had been introduced with chalk, but
+could obtain no evidence to show this."
+
+4. Mr. A. Bennett, of Croydon, has kindly furnished me with some
+information on the temporary vegetation of the banks and cuttings on the
+railway from Yarmouth to Caistor in Norfolk, where it passes over extensive
+sandy Denes with a sparse vegetation. The first year after the railway was
+made the banks produced abundance of _Oenothera odorata_ and _Delphinium
+Ajacis_ (the latter only known thirty miles off in cornfields in
+Cambridgeshire), with _Atriplex patula_ and _A. deltoidea_. Gradually the
+native sand plants--Carices, Grasses, _Galium verum_, &c., established
+themselves, and year by year covered more ground till the new introductions
+almost completely disappeared. The same phenomenon was observed in
+Cambridgeshire between Chesterton and Newmarket, where, the soil being
+different, _Stellaria media_ and other annuals appeared in large patches;
+but these soon gave way to a permanent vegetation of grasses, composites,
+&c., so that in the third year no _Stellaria_ was to be seen.
+
+5. Mr. T. Kirk (writing in 1878) states that--"in Auckland, where a dense
+sward of grass is soon formed, single specimens of the European milk
+Thistle (_Carduus marianus_) have been known for the past fifteen years;
+but although they seeded freely, the seeds had no opportunity of
+germinating, so that the thistle did not spread. A remarkable exception to
+this rule occurred during the formation of the Onehunga railway, where a
+few seeds fell on disturbed soil, grew up and flowered. The railway works
+being suspended, the plant increased rapidly, and spread wherever it could
+find disturbed soil."
+
+Again:--"The fiddle-dock (_Rumex pulcher_) occurs in great abundance on the
+formation of new streets, &c., but soon becomes comparatively rare. It
+seems probable that it was one of the earliest plants naturalised here, but
+that it partially died out, its buried seeds retaining their vitality."
+
+_Medicago sativa_ and _Apium graveolens_, are also noted as escapes from
+cultivation which maintain themselves for a time but soon die out.
+(_Transactions of the New Zealand Institute_, Vol. X. p. 367.)
+
+The preceding examples of the _temporary_ establishment of plants on newly
+exposed soil, often at considerable distances from the localities they
+usually inhabit, might, no doubt, by further inquiry be greatly multiplied;
+but, unfortunately, the phenomenon has received little attention, and is
+not even referred to in the elaborate work of De Candolle (_Géographie
+Botanique Raisonnée_) in which almost every other aspect of the dispersion
+and distribution of plants is fully discussed. Enough has been advanced,
+however, to show that it is of constant occurrence, and from the point of
+view here advocated it becomes of great importance in explaining the almost
+world-wide distribution of many common plants of the north temperate zone.
+
+[192] Sir Joseph Hooker informs me that he considers these identifications
+worthless, and Mr. Bentham has also written very strongly against the value
+of similar identifications by Heer and Unger. Giving due weight to the
+opinions of these eminent botanists we must admit that Australian genera
+have not yet been _demonstrated_ to have existed in Europe during the
+Tertiary period; but, on the other hand, the evidence that they did so
+appears to have some weight, on account of the improbability that the
+numerous resemblances to Australian plants which have been noticed by
+different observers should _all_ be illusory; while the well established
+fact of the former wide distribution of many tropical or now restricted
+types of plants and animals, so frequently illustrated in the present
+volume, removes the antecedent improbability which is supposed to attach to
+such identifications. I am myself the more inclined to accept them,
+because, according to the views here advocated, such migrations must have
+taken place at remote as well as at recent epochs; and the preservation of
+some of these types in Australia while they have become extinct in Europe,
+is exactly paralleled by numerous facts in the distribution of animals
+which have been already referred to in Chapter XIX., and elsewhere in this
+volume, and also repeatedly in my larger work.
+
+[193] Out of forty-two genera from the Eocene of Sheppey enumerated by Dr.
+Ettingshausen in the _Geological Magazine_ for January 1880, only two or
+three appear to be extinct, while there is a most extraordinary
+intermixture of tropical and temperate forms--Musa, Nipa, and Victoria,
+with Corylus, Prunus, Acer, &c. The rich Miocene flora of Switzerland,
+described by Professor Heer, presents a still larger proportion of living
+genera.
+
+[194] The recent discovery by Lieutenant Jensen of a rich flora on rocky
+peaks rising out of the continental ice of Greenland, as well as the
+abundant vegetation of the highest northern latitudes, renders it possible
+that even now the Antarctic continent may not be wholly destitute of
+vegetation, although its climate and physical condition are far less
+favourable than those of the Arctic lands. (See _Nature_, Vol. XXI. p.
+345.)
+
+[195] Dr. Hector notes the occurrence of the genus _Dammara_ in Triassic
+deposits, while in the Jurassic period New Zealand possessed the genera
+_Palæozamia_, _Oleandrium_, _Alethopteris_, _Camptopteris_, _Cycadites_,
+_Echinostrobus_, &c., all Indian forms of the same age. Neocomian beds
+contain a true dicotyledonous leaf with _Dammara_ and _Araucaria_. The
+Cretaceous deposits have produced a rich flora of dicotyledonous plants,
+many of which are of the same genera as the existing flora; while the
+Miocene and other Tertiary deposits produce plants almost identical with
+those now inhabiting the country, together with many North Temperate genera
+which have since become extinct. (See p. 499, footnote, and _Trans. New
+Zealand Inst._, Vol. XI. 1879, p. 536.)
+
+[196] The fact stated in the last edition of the _Origin of Species_ (p.
+340) on the authority of Sir Joseph Hooker, that Australian plants are
+rapidly sowing themselves and becoming naturalised on the Neilgherrie
+mountains in the southern part of the Indian Peninsula, though an exception
+to the rule of the inability of Australian plants to become naturalised in
+the Northern Hemisphere, is yet quite in harmony with the hypothesis here
+advocated. For not only is the climate of the Neilgherries more favourable
+to Australian plants than any part of the North Temperate zone, but the
+entire Indian Peninsula has existed for unknown ages as an _island_ and
+thus possesses the "insular" characteristic of a comparatively poor and
+less developed flora and fauna as compared with the truly "continental"
+Malayan and Himalayan regions. Australian plants are thus enabled to
+compete with those of the Indian Peninsula highlands with a fair chance of
+success.
+
+ * * * * *
+
+
+Corrections made to printed original.
+
+Page 10. "the general stability of continents": 'sontinents' in original.
+
+Pages 35, 250, 361, 363 "oenanthe" read for "ænanthe" throughout for
+consistency
+
+Page 50. "some others of the lower animals": 'animials' in original.
+
+Page 82. "transmission along mountain chains": 'mountains chains' in
+original.
+
+Page 99. "our present land masses": 'massses' in original.
+
+Page 149. "the whole earth should theoretically be": 'thoretically' in
+original.
+
+Page 200. "the flora and fauna, in the British area": 'Brittish' in
+original.
+
+Page 234. "the indications of an uninterrupted warm climate": 'indic-tions'
+on line break in original.
+
+Page 306. "artificially removed by man": 'artifically' in original.
+
+Page 346. "Elachista rufocinerea, the larva of which ...": 'lava' in
+original.
+
+Page 456. "Cynopithecus nigrescens": 'Cynopitheus' in original.
+
+Footnote 100. "S. B. J. Skertchley": 'S. B. K.' in original. I have left
+the name as Skertchley as Wallace uses this spelling almost consistently,
+although Skertchly (as on p. 118) appears to be correct.--Tr.
+
+Footnote 105. "the transportation of the plants": 'transporation' in
+original.
+
+Footnote 110. "Agriolimax campestris": 'Agriolimaoe' (ligand oe) in
+original.
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Island Life, by Alfred Russel Wallace
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