The Geographical Distribution of Animals

by Alfred Russel Wallace

The present work is an attempt to collect and summarize the existing information on the Distribution of Land Animals; and to explain the more remarkable and interesting of the facts, by means of established laws of physical and organic change.

Zoogeographical Regions

THE GEOGRAPHICAL

DISTRIBUTION OF ANIMALS

WITH A STUDY OF
THE RELATIONS OF LIVING AND EXTINCT FAUNAS
AS ELUCIDATING THE
PAST CHANGES OF THE EARTH'S SURFACE.

BY

ALFRED RUSSEL WALLACE,

AUTHOR OF "THE MALAY ARCHIPELAGO," ETC.

WITH MAPS AND ILLUSTRATIONS.

IN TWO VOLUMES.

London:
MACMILLAN AND CO.
1876.

[The Right of Translation and Reproduction is Reserved.]

LONDON:
R. CLAY, SONS, AND TAYLOR, PRINTERS,
BREAD STREET HILL.

CONTENTS OF THE FIRST VOLUME.
PREFACE.
PART I.
THE PRINCIPLES AND GENERAL PHENOMENA OF DISTRIBUTION.
CHAPTER I.
INTRODUCTORY.
CHAPTER II.
THE MEANS OF DISPERSAL AND THE MIGRATIONS OF ANIMALS.
Means of Dispersal of Mammalia (p. 10)—Climate as a Limit to the Range of Mammals (p. 11)—Valleys and Rivers as Barriers to Mammals (p. 12)—Arms of the Sea as Barriers to Mammals (p. 13)—Ice-floes and drift-wood as aiding the Dispersal of Mammals (p. 14)—Means of Dispersal of Birds (p. 15)—Dispersal of Birds by Winds (p. 16)—Barriers to the Dispersal of Birds (p. 17)—The Phenomena of Migration (p. 18)—Migrations of Birds (p. 19)—General remarks on Migration (p. 25)—Means of Dispersal of Reptiles and Amphibia (p. 28)—Means of Dispersal of Fishes (p. 29)—Means of Dispersal of Mollusca (p. 30)—Means of Dispersal of Insects and the Barriers which limit their Range (p. 32)	10-34
CHAPTER III.
DISTRIBUTION AS AFFECTED BY THE CONDITIONS AND CHANGES OF THE EARTH'S SURFACE.
Land and Water (p. 35)—Continental Areas (p. 36)—Recent Changes in the Continental Areas (p. 38)—The Glacial Epoch as affecting the Distribution of Animals (p. 40)—Changes of Vegetation as affecting the Distribution of Animals (p. 43)—Organic Changes as affecting Distribution (p. 44)	35-49
CHAPTER IV.
ON ZOOLOGICAL REGIONS.
Principles upon which Zoological Regions should be formed (p. 53)—Which class of Animals is of most importance in determining Zoological Regions (p. 56)—Various Zoological Regions proposed since 1857 (p. 58)—Discussion of proposed Regions (p. 61)—Reasons for adopting the Six Regions first proposed by Mr. Sclater (p. 63)—Objections to the system of Circumpolar Zones (p. 67)—Does the Arctic Fauna characterise an independent Region (p. 68)—Palæarctic Region (p. 71)—Ethiopian Region (p. 73)—Oriental Region (p. 75)—Australian Region (p. 77)—Neotropical Region (p. 78)—Nearctic Region (p. 79)—Observations on the series of Sub-regions (p. 80)	50-82
CHAPTER V.
CLASSIFICATION AS AFFECTING THE STUDY OF GEOGRAPHICAL DISTRIBUTION.
Classification of the Mammalia (p. 85)—Classification of Birds (p. 92)—Classification of Reptiles (p. 98)—Classification of Amphibia (p. 100)—Classification of Fishes (p. 101)—Classification of Insects (p. 102)—Classification of Mollusca (p. 104)	83-104
PART II.
ON THE DISTRIBUTION OF EXTINCT ANIMALS.
CHAPTER VI.
THE EXTINCT MAMMALIA OF THE OLD WORLD.
Historic and Post-pliocene Period (p. 110)—Pliocene Period (p. 112)—General Conclusions as to the Pliocene and Post-pliocene Faunas of Europe (p. 113)—Miocene Period (p. 114)—Extinct Animals of Greece (p. 115)—Miocene Fauna of Central and Western Europe (p. 117)—Upper Miocene Deposits of India (p. 121)—General Observations on the Miocene Faunas of Europe and Asia (p. 123)—Eocene Period (p. 124)—General Considerations on the Extinct Mammalian Fauna of Europe (p. 126)	83-104
CHAPTER VII.
EXTINCT MAMMALIA OF THE NEW WORLD.
North America—Post-pliocene Period (p. 129)—Remarks on the Post-pliocene Fauna of North America (p. 130)—Tertiary Period (p. 132)—Primates (p. 132)—Insectivora (p. 133)—Carnivora (p. 134)—Ungulata (p. 135)—Proboscidea (p. 138)—Tillodontia (p. 139)—Rodentia (p. 140)—General Relations of the Extinct Tertiary Mammalia of North America and Europe (p. 140)—South America (p. 143)—Fauna of the Brazilian Caves (p. 143)—Pliocene Period of Temperate South America (p. 146)—Pliocene Mammalia of the Antilles (p. 148)—Eocene Fauna of South America (p. 148)—General Remarks on the Extinct Mammalian Fauna of the Old and New Worlds (p. 148)—The Birth-place and Migrations of some Mammalian Families and Genera (p. 153)	129-156
CHAPTER VIII.
VARIOUS EXTINCT ANIMALS;—AND ON THE ANTIQUITY OF THE GENERA OF INSECTS AND LAND-MOLLUSCA.
Extinct Mammalia of Australia (p. 157)—Mammalian Remains of the Secondary Formations (p. 159)—Extinct Birds (p. 160)—Palæarctic Region and North India (p. 161)—North America (p. 163)—South America, Madagascar, New Zealand (p. 164)—Extinct Tertiary Reptiles (p. 165)—Antiquity of the Genera of Insects (p. 166)—Antiquity of the Genera of Land and Fresh-water Shells (p. 168)	157-170
PART III.
ZOOLOGICAL GEOGRAPHY: A REVIEW OF THE CHIEF FORMS OF LIFE IN THE SEVERAL REGIONS AND SUB-REGIONS, WITH THE INDICATIONS THEY AFFORD OF GEOGRAPHICAL MUTATIONS.
CHAPTER IX.
THE ORDER OF SUCCESSION OF THE REGIONS.—COSMOPOLITAN GROUPS OF ANIMALS.—TABLES OF DISTRIBUTION.
Order of succession of the Regions (p. 173)—Cosmopolitan Groups (p. 175)—Tables of Distributions of Families and Genera (p. 177)	173-179
CHAPTER X.
THE PALÆARCTIC REGION.
Zoological Characteristics of the Palæarctic Region (p. 181)—Summary of Palæarctic Vertebrata (p. 186)—Insects (p. 187)—Land-shells (p. 190)—The Palæarctic Sub-regions (p. 190)—Central and Northern Europe (p. 191)—North European Islands (p. 197)—Mediterranean Sub-region (p. 199)—The Mediterranean and Atlantic Islands (p. 206)—The Siberian Sub-region, or Northern Asia (p. 216)—Japan and North China, or the Manchurian Sub-region (p. 220)—Birds (p. 223)—Insects (p. 227)—Remarks on the General Character of the Fauna of Japan (p. 230)—General Conclusions as to the Fauna of the Palæarctic Region (p. 231)—Table I. Families of Animals inhabiting the Palæarctic Region (p. 234)—Table II. List of the Genera of Terrestrial Mammalia and Birds of the Palæarctic Region (p. 239)	181-250
CHAPTER XI.
THE ETHIOPIAN REGION.
Zoological Characteristics of the Ethiopian Region (p. 252)—Summary of Ethiopian Vertebrates (p. 255)—The Ethiopian Sub-regions (p. 258)—The East African Sub-region, or Central and East Africa (p. 258)—The West African Sub-region (p. 262)—Islands of the West African Sub-region (p. 265)—South African Sub-region (p. 266)—Atlantic Islands of the Ethiopian Region;—St. Helena (p. 269)—Tristan d'Acunha (p. 271)—Madagascar and the Mascarene Islands, or the Malagasy Sub-region (p. 272)—The Mascarene Islands (p. 280)—Extinct Fauna of the Mascarene Islands and Madagascar (p. 282)—General Remarks on the Insect Fauna of Madagascar (p. 284)—On the probable Past History of the Ethiopian Region (p. 285)—Table I. Families of Animals inhabiting the Ethiopian Region (p. 294)—Table II. List of Genera of Terrestrial Mammalia and Birds of the Ethiopian Region (p. 300)	251-313
CHAPTER XII.
THE ORIENTAL REGION.
Zoological Characteristics of the Oriental Region (p. 315)—Summary of Oriental Vertebrata (p. 318)—The Oriental Sub-regions (p. 321)—Hindostan, or Indian Sub-region (p. 321)—Range of the Genera of Mammalia which inhabit the Sub-region of Hindostan (p. 322)—Oriental, Palæarctic, and Ethiopian Genera of Birds in Central India (p. 224)—Sub-region of Ceylon and South India (p. 326)—The Past History of Ceylon and South India, as indicated by its Fauna (p. 328)—Himalayan or Indo-Chinese Sub-region (p. 329)—Islands of the Indo-Chinese Sub-region (p. 333)—Indo-Malaya, or the Malayan Sub-region (p. 334)—Malayan Insects (p. 341)—The Zoological Relations of the several Islands of the Indo-Malay Sub-region (p. 345)—Philippine Islands (p. 345)—Java (p. 349)—Malacca, Sumatra, and Borneo (p. 353)—Probable recent Geographical Changes in the Indo-Malay Islands (p. 357)—Probable Origin of the Malayan Fauna (p. 359)—Concluding Remarks on the Oriental Region (p. 362)—Table I. Families of Animals inhabiting the Oriental Region (p. 365)—Table II. Genera of Terrestrial Mammalia and Birds in the Oriental Region (p. 371)	314-386
CHAPTER XIII.
THE AUSTRALIAN REGION.
General Zoological Characteristics of the Australian Region (p. 390)—Summary of the Australian Vertebrata (p. 397)—Supposed Land-connection between Australia and South America (p. 398)—Insects (p. 403)—Land-shells (p. 407)—Australian Sub-regions (p. 408)—Austro-Malayan Sub-region (p. 409)—Papua, or the New Guinea Group (p. 409)—The Moluccas (p. 417)—Insects—Peculiarities of the Moluccan Fauna (p. 420)—Timor Group (p. 422)—Celebes Group (p. 426)—Origin of the Fauna of Celebes (p. 436)—Australia and Tasmania, or the Australian Sub-region (p. 438)—The Pacific Islands, or Polynesian Sub-region (p. 442)—Fiji, Tonga, and Samoa Islands (p. 443)—Society and Marquesas Islands (p. 443)—Ladrone and Caroline Islands (p. 444)—New Caledonia and the New Hebrides (p. 444)—Sandwich Islands (p. 445)—Reptiles of the Polynesian Sub-region (p. 448)—New Zealand Sub-region (p. 449)—Islets of the New Zealand Sub-region (p. 453)—Reptiles, Amphibia, and Fresh-water Fishes (p. 456)—Insects (p. 457)—The Ancient Fauna of New Zealand (p. 459)—The Origin of the New Zealand Fauna (p. 459)—Causes of the Poverty of Insect-life in New Zealand: its Influence on the Character of the Flora (p. 462)—Concluding Remarks on the Early History of the Australian Region (p. 464)—Table I. Families of Animals inhabiting the Australian Region (p. 468)—Table II. Genera of Terrestrial Mammalia and Birds of the Australian Region (p. 473)	387-485
Index to Vol. I	489-503
CONTENTS OF THE SECOND VOLUME.
PART III. (continued).
ZOOLOGICAL GEOGRAPHY: A REVIEW OF THE CHIEF FORMS OF ANIMAL LIFE IN THE SEVERAL REGIONS AND SUB-REGIONS, WITH THE INDICATIONS THEY AFFORD OF GEOGRAPHICAL MUTATIONS.
CHAPTER XIV.
THE NEOTROPICAL REGION.
General Zoological Features of the Neotropical Region (p. 5)—Distinctive Characters of Neotropical Mammalia (p. 6)—Of Neotropical Birds (p. 7)—Neotropical Reptiles (p. 9)—Fresh-water Fishes (p. 12)—Insects (p. 13)—Coleoptera (p. 15)—Land Shells (p. 19)—Marine Shells (p. 20)—Brazilian Sub-region (p. 21)—Its Mammalia (p. 23)—Its Birds (p. 24)—Islands of Tropical South America, Galapagos (p. 29)—Chilian Sub-region (p. 36)—Birds (p. 38)—Reptiles and Amphibia (p. 40)—Fresh-water Fishes (p. 42)—Lepidoptera (p. 42)—Coleoptera (p. 44)—Islands of South Temperate America (p. 49)—Mexican Sub-region (p. 51)—Mammalia and Birds (p. 52)—Reptiles and Fishes (p. 54)—Insects (p. 55)—Relations of the Mexican Sub-region to the North and South American Continents (p. 57)—Islands of the Mexican Sub-region (p. 59)—The Antillean Sub-region (p. 60)—Its Mammalia (p. 62)—Its Birds (p. 64)—Table of the Resident Land Birds of the Antilles (p. 68)—Reptiles (p. 72)—Insects (p. 73)—Land Shells (p. 75)—Past History of the Antilles (p. 78)—Summary of the Past History of the Neotropical Region (p. 80)—Table I. Families of Animals inhabiting the Neotropical Region (p. 85)—Table II. Genera of Terrestrial Mammalia and Birds of the Neotropical Region (p. 91)	1-113
CHAPTER XV.
THE NEARCTIC REGION.
Zoological Characteristics of the Nearctic Region (p. 115)—List of Typical Nearctic Genera of Land Birds (p. 118)—Summary of Nearctic Vertebrata (p. 120)—Insects (p. 122)—Terrestrial and Fluviatile Mollusca (p. 124)—The Californian Sub-region (p. 127)—The Rocky Mountain Sub-region (p. 129)—The Alleghany Sub-region (p. 131)—The Bermudas (p. 134)—The Canadian Sub-region (p. 135)—Greenland (p. 138)—Table I. Families of Animals inhabiting the Nearctic Region (p. 140)—Table II. Genera of Terrestrial Mammalia and Birds of the Nearctic Region (p. 145)	114-153
CHAPTER XVI.
SUMMARY OF THE PAST CHANGES AND GENERAL RELATIONS OF THE SEVERAL REGIONS
PART IV.
GEOGRAPHICAL ZOOLOGY: A SYSTEMATIC SKETCH OF THE CHIEF FAMILIES OF LAND ANIMALS IN THEIR GEOGRAPHICAL RELATIONS.
Introduction	167-169
CHAPTER XVII.
THE DISTRIBUTION OF THE FAMILIES AND GENERA OF MAMMALIA.
Primates (p. 170)—General Remarks on the Distribution of Primates (p. 179)—Chiroptera (p. 181)—Remarks on the Distribution of Chiroptera (p. 185)—Insectivora (p. 186)—General Remarks on the Distribution of Insectivora (p. 191)—Carnivora (p. 192)—General Remarks on the Distribution of the Carnivora (p. 204)—Cetacea (p. 207)—Sirenia (p. 210)—Ungulata (p. 211)—General Remarks on the Distribution of the Ungulata (p. 226)—Proboscidea (p. 227)—Hyracoidea (p. 228)—Rodentia (p. 229)—General Remarks on the Distribution of the Rodentia (p. 243)—Edentata (p. 244)—General Remarks on the Distribution of the Edentata (p. 247)—Marsupialia (p. 248)—General Remarks on the Distribution of Marsupialia (p. 253)—Monotremata (p. 253)	170-254
CHAPTER XVII.
THE DISTRIBUTION OF THE FAMILIES AND GENERA OF BIRDS.
Passeres (p. 255)—General Remarks on the Distribution of the Passeres (p. 299)—Picariæ (p. 302)—General Remarks on the Distribution of the Picariæ (p. 322)—Psittaci (p. 324)—General Remarks on the Distribution of the Psittaci (p. 329)—Columbæ (p. 331)—General Remarks on the Distribution of the Columbæ (p. 335)—Gallinæ (p. 337)—General Remarks on the Distribution of Gallinæ (p. 344)—Opisthocomi (p. 345)—Accipitres (p. 345)—General Remarks on the Distribution of the Accipitres (p. 351)—Grallæ (p. 351)—General Remarks on the Distribution of the Grallæ (p. 362)—Anseres (p. 363)—General Remarks on the Distribution of the Anseres (p. 367)—Struthiones (p. 368)—Struthious Birds recently Extinct (p. 369)—General Remarks on the Distribution of the Struthiones (p. 370)	255-371
CHAPTER XIX.
THE DISTRIBUTION OF THE FAMILIES AND GENERA OF REPTILES AND AMPHIBIA.
Ophidia (p. 372)—General Remarks on the Distribution of Ophidia (p. 386)—Lacertilia (p. 388)—General Remarks on the Distribution of Lacertilia (p. 403)—Rhynchocephalina (p. 405)—Crocodilia (p. 405)—General Remarks on the Distribution of Crocodilia (p. 406)—Chelonia (p. 407)—Remarks on the Distribution of Chelonia (p. 410)—Amphibia, Pseudophidia (p. 411)—Urodela (p. 411)—Anura (p. 414)—General Remarks on the Distribution of Amphibia (p. 422)	372-423
CHAPTER XX.
THE DISTRIBUTION OF THE FAMILIES OF FISHES, WITH THE RANGE OF SUCH GENERA AS INHABIT FRESH WATER.
Acanthopterygii (p. 424)—-Acanthopterygii Pharyngognathi (p. 437)—Anacanthini (p. 439)—Physostomi (p. 441)—Lophobranchii (p. 456)—Plectognathi (p. 457)—Sirenoidei (p. 458)—Ganoidei (p. 458)—Chondropterygii (p. 460)—Cyclostomata (p. 463)—Leptocardii (p. 464)—Remarks on the Distribution of Fishes (p. 464)	424-467
CHAPTER XXI.
THE DISTRIBUTION OF SOME OF THE MORE IMPORTANT FAMILIES AND GENERA OF INSECTS.
Lepidoptera (p. 470)—General Remarks on the Distribution of the Diurnal Lepidoptera and Sphingidea (p. 483)—Coleoptera (p. 486)—Cicindelidæ (p. 486)—Carabidæ (p. 488)—Lucanidæ (p. 492)—Cetoniidæ (p. 494)—Buprestidæ (p. 495)—Longicornia (p. 498)—General Observations on the Distribution of Coleoptera (p. 502)	468-503
CHAPTER XXII.
AN OUTLINE OF THE GEOGRAPHICAL DISTRIBUTION OF MOLLUSCA.
Cephalopoda (p. 505)—Gasteropoda (p. 507)—Pulmonifera (p. 512)—General Observations on the Distribution of Land Mollusca (p. 522)—Pteropoda (p. 531)—Brachiopoda (p. 532)—Conchifera (p. 533)—General Remarks on the Distribution of Marine Mollusca (p. 537)	504-539
CHAPTER XXIII.
SUMMARY OF THE DISTRIBUTION AND LINES OF MIGRATION OF THE SEVERAL CLASSES OF ANIMALS.
Mammalia (p. 540)—Lines of Migration of the Mammalia (p. 544)—Birds (p. 545)—Reptiles (p. 547)—Amphibia (p. 548)—Fresh-water Fishes (p. 549)—Insects (p. 550)—Terrestrial Mollusca (p. 551)—Conclusion (p. 552)	540-553
General Index	557

	MAPS AND ILLUSTRATIONS IN VOL. I.
1.	Map of the World, showing the Zoo-Geographical Regions and the contour of the Ocean-bed			Frontispiece
				To face page
2.	Map of the Palæarctic Region			181
3.	Plate	I.	The Alps of Central Europe with Characteristic Animals	195
4.	Plate	II.	Characteristic Mammalia of Western Tartary	218
5.	Plate	III.	Characteristic Animals of North China	226
6.	Map of the Ethiopian Region			251
7.	Plate	IV.	Characteristic Animals of East Africa	261
8.	Plate	V.	Scene in West Africa with Characteristic Animals	264
9.	Plate	VI.	Scene in Madagascar with Characteristic Animals	278
10.	Map of the Oriental Region			315
11.	Plate	VII.	Scene in Nepaul with Characteristic Animals	331
12.	Plate	VIII.	A Forest in Borneo with Characteristic Mammalia	337
13.	Plate	IX.	A Malacca Forest with some of its Peculiar Birds	340
14.	Map of the Australian Region			387
15.	Plate	X.	Scene in New Guinea with Characteristic Animals	415
16.	Plate	XI.	The Characteristic Mammalia of Tasmania	439
17.	Plate	XII.	The Plains of New South Wales with Characteristic Animals	442
18.	Plate	XIII.	Scene in New Zealand with some of its Remarkable Birds	455
	MAPS AND ILLUSTRATIONS IN VOL. II.
				To face page
1.	Map of the Neotropical Region			3
2.	Plate	XIV.	A Brazilian Forest with Characteristic Mammalia	24
3.	Plate	XV.	A Scene on the Upper Amazon, with some Characteristic Birds	28
4.	Plate	XVI.	The Chilian Andes, with Characteristic Animals	40
5.	Plate	XVII.	A Scene in Cuba, with Characteristic Animals	67
6.	Map of the Nearctic Region			115
7.	Plate	XVIII.	Scene in California with some Characteristic Birds	128
8.	Plate	XIX.	The North American Prairies with Characteristic Mammalia	130
9.	Plate	XX.	A Canadian Forest with Characteristic Mammalia	136

PREFACE.

The main idea, which is here worked out in some detail for the whole earth, was stated sixteen years ago in the concluding pages of a paper on the "Zoological Geography of the Malay Archipelago," which appeared in the Journal of Proceedings of the Linnean Society for 1860; and again, in a paper read before the Royal Geographical Society in 1863, it was briefly summarized in the following passage:—

"My object has been to show the important bearing of researches into the natural history of every part of the world, upon the study of its past history. An accurate knowledge of any groups of birds or of insects and of their geographical distribution, may enable us to map out the islands and continents of a former epoch,—the amount of difference that exists between the animals of adjacent districts being closely related to preceding geological changes. By the collection of such minute facts, alone, can we hope to fill up a great gap in the past history of the earth as revealed by geology, and obtain some indications of the existence of those ancient lands which now lie buried beneath the ocean, and have left us nothing but these living records of their former existence."

The detailed study of several groups of the birds and insects collected by myself in the East, brought prominently before me some of the curious problems of Geographical Distribution; but I should hardly have ventured to treat the whole subject, had it not been for the kind encouragement of Mr. Darwin and Professor Newton, who, about six years ago, both suggested that I should undertake the task. I accordingly set to work; but soon became discouraged by the great dearth of materials in many groups, the absence of general systematic works, and the excessive confusion that pervaded the classification. Neither was it easy to decide on any satisfactory method of treating the subject. During the next two years, however, several important catalogues and systematic treatises appeared, which induced me to resume my work; and during the last three years it has occupied a large portion of my time.

After much consideration, and some abortive trials, an outline plan of the book was matured; and as this is, so far as I am aware, quite novel, it will be well to give a few of the reasons for adopting it.

Most of the previous writings on Geographical Distribution appeared to me to be unsatisfactory, because they drew their conclusions from a more or less extensive selection of facts; and did not clearly separate groups of facts of unequal value, or those relating to groups of animals of unequal rank. As an example of what is meant, I may refer to Mr. Andrew Murray's large and valuable work on the Geographical Distribution of Mammalia, in which an immense number of coloured maps are used to illustrate the distribution of various groups of animals. These maps are not confined to groups of any fixed rank, but are devoted to a selection of groups of various grades. Some show the range of single species of a genus—as the lion, the tiger, the puma, and a species of fox; others are devoted to sections of genera,—as the true wolves; others to genera,—as the hyænas, and the bears; others to portions of families,—as the flying squirrels, and the oxen with the bisons; others to families,—as the Mustelidæ, and the Hystricidæ; and others to groups of families or to orders,—as the Insectivora, and the opossums with the kangaroos. But in no one grade are all the groups treated alike. Many genera are wholly unnoticed, while several families are only treated in combination with others, or are represented by some of the more important genera.

In making these observations I by no means intend to criticise Mr. Murray's book, but merely to illustrate by an example, the method which has been hitherto employed, and which seems to me not well adapted to enable us to establish the foundations of the science of distribution on a secure basis. To do this, uniformity of treatment appeared to me essential, both as a matter of principle, and to avoid all imputation of a partial selection of facts, which may be made to prove anything. I determined, therefore, to take in succession every well-established family of terrestrial vertebrates, and to give an account of the distribution of all its component genera, as far as materials were available. Species, as such, are systematically disregarded,—firstly, because they are so numerous as to be unmanageable; and, secondly, because they represent the most recent modifications of form, due to a variety of often unknown causes, and are therefore not so clearly connected with geographical changes as are the natural groups of species termed genera; which may be considered to represent the average and more permanent distribution of an organic type, and to be more clearly influenced by the various known or inferred changes in the organic and physical environment.

This systematic review of the distribution of families and genera, now forms the last part of my book—Geographical Zoology; but it was nearly the first written, and the copious materials collected for it enabled me to determine the zoo-geographical divisions of the earth (regions and sub-regions) to be adopted. I next drew up tables of the families and genera found in each region and sub-region; and this afforded a basis for the geographical treatment of the subject—Zoological Geography—the most novel, and perhaps the most useful and generally interesting part of my work. While this was in progress I found it necessary to make a careful summary of the distribution of extinct Mammalia. This was a difficult task, owing to the great uncertainty that prevails as to the affinities of many of the fossils, and my want of practical acquaintance with Palæontology; but having carefully examined and combined the works of the best authors, I have given what I believe is the first connected sketch of the relation of extinct Mammalia to the distribution of living groups, and have arrived at some very interesting and suggestive results.

It will be observed that man is altogether omitted from the series of the animal kingdom as here given, and some explanation of this omission may perhaps be required. If the genus Homo had been here treated like all other genera, nothing more than the bare statement—"universally distributed"—could have been given;—and this would inevitably have provoked the criticism that it conveyed no information. If, on the other hand, I had given an outline of the distribution of the varieties or races of man, I should have departed from the plan of my work for no sufficient reason. Anthropology is a science by itself; and it seems better to omit it altogether from a zoological work, than to treat it in a necessarily superficial manner.

The best method of illustrating a work of this kind was a matter requiring much consideration. To have had a separate coloured or shaded map for each family would have made the work too costly, as the terrestrial vertebrates alone would have required more than three hundred maps. I had also doubts about the value of this mode of illustration, as it seemed rather to attract attention to details than to favour the development of general views. I determined therefore to adopt a plan, suggested in conversation by Professor Newton; and to have one general map, showing the regions and sub-regions, which could be referred to by means of a series of numbers. These references I give in the form of diagrammatic headings to each family; and, when the map has become familiar, these will, I believe, convey at a glance a body of important information.

Taking advantage of the recent extension of our knowledge of the depths of the great oceans, I determined to give upon this map a summary of our knowledge of the contours of the ocean bed, by means of tints of colour increasing in intensity with the depth. Such a map, when it can be made generally accurate, will be of the greatest service in forming an estimate of the more probable changes of sea and land during the Tertiary period; and it is on the effects of such changes that any satisfactory explanation of the facts of distribution must to a great extent depend.

Other important factors in determining the actual distribution of animals are, the zones of altitude above the sea level, and the strongly contrasted character of the surface as regards vegetation—a primary condition for the support of animal life. I therefore designed a series of six maps of the regions, drawn on a uniform scale, on which the belts of altitude are shown by contour-shading, while the forests, pastures, deserts, and perennial snows, are exhibited by means of appropriate tints of colour.

These maps will, I trust, facilitate the study of geographical distribution as a science, by showing, in some cases, an adequate cause in the nature of the terrestrial surface for the actual distribution of certain groups of animals. As it is hoped they will be constantly referred to, double folding has been avoided, and they are consequently rather small; but Mr. Stanford, and his able assistant in the map department, Mr. Bolton, have taken great care in working out the details from the latest observations; and this, combined with the clearness and the beauty of their execution, will I trust render them both interesting and instructive.

In order to make the book more intelligible to those readers who have no special knowledge of systematic zoology, and to whom most of the names with which its pages are often crowded must necessarily be unmeaning, I give a series of twenty plates, each one illustrating at once the physical aspect and the special zoological character of some well-marked division of a region. Great care has been taken to associate in the pictures, such species only as do actually occur together in nature; so that each plate represents a scene which is, at all events, not an impossible one. The species figured all belong to groups which are either peculiar to, or very characteristic of, the region whose zoology they illustrate; and it is hoped that these pictures will of themselves serve to convey a notion of the varied types of the higher animals in their true geographical relations. The artist, Mr. J. B. Zwecker, to whose talent as a zoological draughtsman and great knowledge both of animal and vegetable forms we are indebted for this set of drawings, died a few weeks after he had put the final touches to the proofs. He is known to many readers by his vigorous illustrations of the works of Sir Samuel Baker, Livingstone, and many other travellers,—but these, his last series of plates, were, at my special request, executed with a care, delicacy, and artistic finish, which his other designs seldom exhibit. It must, however, be remembered, that the figures of animals here given are not intended to show specific or generic characters for the information of the scientific zoologist, but merely to give as accurate an idea as possible, of some of the more remarkable and more restricted types of beast and bird, amid the characteristic scenery of their native country;—and in carrying out this object there are probably few artists who would have succeeded better than Mr. Zwecker has done.

 

The general arrangement of the separate parts of which the work is composed, has been, to some extent, determined by the illustrations and maps, which all more immediately belong to Part III. It was at first intended to place this part last, but as this arrangement would have brought all the illustrations into the second volume, its place was changed,—perhaps in other respects for the better, as it naturally follows Part II. Yet for persons not well acquainted with zoology, it will perhaps be advisable to read the more important articles of Part IV. (and especially the observations at the end of each order) after Part II., thus making Part III. the conclusion of the work.

Part IV. is, in fact, a book of reference, in which the distribution of all the families and most of the genera of the higher animals, is given in systematic order. Part III. is treated somewhat more popularly; and, although it is necessarily crowded with scientific names (without which the inferences and conclusions would have nothing solid to rest on), these may be omitted by the non-scientific reader, or merely noted as a certain number or proportion of peculiar generic types. Many English equivalents to family and generic names are, however, given; and, assisted by these, it is believed that any reader capable of understanding Lyell's "Principles," or Darwin's "Origin," will have no difficulty in following the main arguments and appreciating the chief conclusions arrived at in the present work.

To those who are more interested in facts than in theories, the book will serve as a kind of dictionary of the geography and affinities of animals. By means of the copious Index, the native country, the systematic position, and the numerical extent of every important and well established genus of land-animal may be at once discovered;—information now scattered through hundreds of volumes.

In the difficult matters of synonymy, and the orthography of generic names, I have been guided rather by general utility than by any fixed rules. When I have taken a whole family group from a modern author of repute, I have generally followed his nomenclature throughout. In other cases, I use the names which are to be found in a majority of modern authors, rather than follow the strict rule of priority in adopting some newly discovered appellation of early date. In orthography I have adopted all such modern emendations as seem coming into general use, and which do not lead to inconvenience; but where the alteration is such as to completely change the pronunciation and appearance of a well-known word, I have not adopted it. I have also thought it best to preserve the initial letter of well-known and old-established names, for convenience of reference to the Indices of established works. As an example I may refer to Enicurus,—a name which has been in use nearly half a century, and which is to be found under the letter E, in Jerdon's Birds of India, Blyth's Catalogue, Bonaparte's Conspectus, and the Proceedings of the Zoological Society of London down to 1865. Classicists now write Henicurus as the correct form; but this seems to me one of those cases in which orthographical accuracy should give way to priority, and still more to convenience.

In combining and arranging so much detail from such varied sources, many errors and omissions must doubtless have occurred. Owing to my residence at a distance from the scientific libraries of the metropolis, I was placed at a great disadvantage; and I could hardly have completed the work at all, had I not been permitted to have a large number of volumes at once, from the library of the Zoological Society of London, and to keep them for months together;—a privilege for which I return my best thanks to Mr. Sclater the Secretary, and to the Council.

Should my book meet with the approval of working naturalists, I venture to appeal to them, to assist me in rendering any future editions more complete, by sending me (to the care of my publishers) notes of any important omissions, or corrections of any misstatements of fact; as well as copies of any of their papers or essays, and especially of any lists, catalogues, and monographs, containing information on the classification or distribution of living or extinct animals.

 

To the many friends who have given me information or assistance I beg to tender my sincere thanks. Especially am I indebted to Professor Newton, who not only read through much of my rough MSS., but was so good as to make numerous corrections and critical notes. These were of great value to me, as they often contained or suggested important additional matter, or pointed out systematic and orthographical inaccuracies.

Professor Flower was so good as to read over my chapters on extinct animals, and to point out several errors into which I had fallen.

Dr. Günther gave me much valuable information on the classification of reptiles, marking on my lists the best established and most natural genera, and referring me to reliable sources of information.

I am also greatly indebted to the following gentlemen for detailed information on special subjects:—

To Sir Victor Brooke, for a MS. arrangement of the genera of Bovidæ, with the details of their distribution:

To Mr. Dresser, for lists of the characteristic birds of Northern and Arctic Europe:

To Dr. Hooker, for information on the colours and odours of New Zealand plants:

To Mr. Kirby, for a list of the butterflies of Chili:

To Professor Mivart, for a classification of the Batrachia, and an early proof of his article on "Apes" in the Encyclopedia Britannica:

To Mr. Salvin, for correcting my list of the birds of the Galapagos, and for other assistance:

To Mr. Sharpe, for MS. lists of the birds of Madagascar and the Cape Verd Islands:

To Canon Tristram, for a detailed arrangement of the difficult family of the warblers,—Sylviidæ:

To Viscount Walden, for notes on the systematic arrangement of the Pycnonotidæ and Timaliidæ, and for an early proof of his list of the birds of the Philippine Islands.

I also have to thank many naturalists, both in this country and abroad, who have sent me copies of their papers; and I trust they will continue to favour me in the same manner.

An author may easily be mistaken in estimating his own work. I am well aware that this first outline of a great subject is, in parts, very meagre and sketchy; and, though perhaps overburthened with some kinds of detail, yet leaves many points most inadequately treated. It is therefore with some hesitation that I venture to express the hope that I have made some approach to the standard of excellence I have aimed at;—which was, that my book should bear a similar relation to the eleventh and twelfth chapters of the "Origin of Species," as Mr. Darwin's "Animals and Plants under Domestication" does to the first chapter of that work. Should it be judged worthy of such a rank, my long, and often wearisome labours, will be well repaid.

March, 1876.