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territory is in the highest degree indefinite. To speak, for instance, of India as the habitat of the tiger, is to in perfectly indicate the range of that animal, which extends over at least two-thirds of the continent, besides being found in the Eastern Archipelago. Or, if we select one or two common British quadrupeds, we may find the anomalies of the common method of naming the habitats of animals to be equally well represented. For instance, the badger is commonly described as being found in Europe. Such a method of denoting its range tends to imply that its distribution is limited to that continent. But in point of fact, the badger ranges eastwards from Central Asia to Amoor, and southwards to North Africa as well. The otter's distribution ranges to North Africa, and extends to Siberia ; the hedgehog is found from Central Asia to Amoor, like the badger ; and the mole extends as far as Central Asia. Certain of our birds fall equally without the common indications of distribution. Our grey wagtail (Motacilla sulphurea) extends to North Africa, and occurs also in Central Asia, China, and Malaya ; and the house-sparrow, fieldfare, starling, and crow, have a distribution varying from Britain to North Africa and Central Asia. The inadequacy of ordinary descriptive geography to indicate the range of these animals can therefore be readily understood. In the nature of things, the distribution of animals and plants follows certain laws which have left their impress upon the boundaries of land-regions likewise. It remains for us to see how the earth's surface has been mapped out by these laws into natural continents or regions, each characterised by its own characteristic fauna and flora.
The popular description of animal and plant distribution, moreover, besides
affording no exact details of the boundaries of its regions, gives no information concerning the causes which limit an animal to a small area in one case, or which extend an animal's range over a wide area in another. On the contrary, when, taking as our guide the natural divisions of earth's population, we discover the exact distribution of animals and plants, we lay thereby
the foundation of the knowledge which shows how that distribution has been attained and regulated. It is not sufficient, for instance, for any intellectual purpose, to know why kangaroos are found in Australia alone. The mind
naturally proceeds further, and inquires, why should these animals be limited to the region in question? It by no means conveys any adequate information concerning the distribution of the marsupial or “pouched” order of quadrupeds to be told that all known members of the group, kangaroos included, are confined to the Australian region, with the single exception of the true opossums or Didelphida—these latter animals occurring in the New World, but being absent from Australia. The natural queries, why should kangaroos be confined to Australia, and why should the opossums (Fig. 2) alone of all marsupials be found without the bounds of Australia, are not answered by the mere geographical descriptions of former days. Nor do these descriptions indicate why, to select other examples, Australia is practically destitute of all higher quadrupeds; or why antelopes have their head-quarters in Africa, where, south of the great desert, deer do not typically occur, whilst deer are found in all other regions save Australia. So also the mere note of an animal's country as politically defined, and the mention of the fact that bears inhabit Europe, Asia, and North America, gives no explanation why these animals are absent from tropical and South Africa. The pigs, again, are common over Europe and Asia down to New Guinea, yet Southern Africa knows not this race any more than it includes the deer amongst its denizens. Nor can we explain according to ordinary geographical notions, why tapirs should exist in regions so far apart as Malaya and South Africa, or why camels and llamas should inhabit the Asian deserts and the slopes of the Andes respectively. Or, last of all, how impossible of explanation, on ordinary grounds, is the fact that the anthropoid or man-like apes occur in regions so widely separated as Western Africa and Borneo. It is clear, therefore, that our glance at the world's geography in relation to the distribution of life must go deeper into the nature of things than do the common descriptions of the countries tenanted by animal and plant races. Here, as in other departments of scientific inquiry, we require to refer to a former state of things, and to glance backwards in time for the true solution of the problems of life's development over the globe. The naturalist of to-day thoroughly endorses Mr. Wallace's statement, that “to the older school of naturalists the native country of an animal was of little importance except in so far as climates differed. . . . . A group of animals was said to inhabit the ‘Indies'; and important differences of structure were often overlooked from the idea that creatures equally adapted to live in hot countries, and with certain general resemblances, would naturally be related to each other. . . . . To the modern naturalist,
on the other hand, the native country (or 'habitat,' as it is technically termed) of an animal or a group of animals is a matter of the first importance; and as regards the general history of life upon the globe, may be considered to be one of its essential characters."
That certain divisions, or "regions,” bounded by distinct lines of demarcation, exist to represent the natural method of distribution of animals or plants on the earth's surface, is a fact readily provable. For example, one of the most remarkable results attained through the investigation of the distribution of animals and plants, is the fact that a line passing between the little islands of Bali and Lombok in the eastern archipelago, and separating Borneo, Java, and the Philippines from Celebes, New Guinea, and Australia (see Fig. 1), serves as a boundary between two regions exhibiting the greatest diversity in their animal and plant life. On the Borneo side of this line we have a rich collection of higher quadruped life-man-like apes, lemurs, monkeys, antelopes, tigers, rhinoceroses, and other formsalong with the babblers, hill-tits, bulbuls, crows, hornbills, pheasants, and jungle-fowl among the birds. On the Australian side, not a single higher quadruped (if we except a few bats, and rodents of recent introduction) is native; and the kangaroos and their neighbours represent the fulness of quadruped life in the archipelago. The special birds of the archipelago have for the most part disappeared. The bulbuls, pheasants, barbets, and vultures, find no place in the Australian islands; but in their place we find the curious honey-suckers, the piping crows, the lyre-birds, the cockatoos, lories, and parroquets, the brush-turkey and mound birds, emus and cassowaries, and other characteristic forms. It is difficult to imagine a change of fauna so complete as that which meets the eye of the traveller as he passes across the narrow straits of Lombok to enter the Australian region. Yet the divergence is of the most characteristic nature, and depends upon the causes which lie at the root not merely of physical but of biological change. The remarkable fact that the animals common to Europe and Central Asia pass into Africa north of the desert, but are not, as a rule, found in India, is similarly explicable on the ground that the distribution of life shows us the natural divisions and natural geography of the globe. It now remains to investigate the limits and boundaries of these divisions (or “zoological regions," as they are named), to indicate the more familiar types of life resident in each, and to ascertain, last of all, the chief facts which, when brought into scientific relationship, serve to explain how and why the life of the earth has been thus distributed.
Mr. Sclater, the secretary of the Zoological Society of London, proposed, from a consideration of the bird-life of the globe, to divide the earth's surface into six provinces or regions. These regions, whilst indicating the distribution of the birds, likewise serve to show that of the quadrupeds; whilst it is found that they also represent the essential features of the distribution of still lower grades of life. Mr. Sclater's six divisions have received, with one or two modifications, the common approval of naturalists. Professor Huxley, it is true, has proposed a somewhat different division of the earth's surface, and it may be convenient in the first place to note this latter arrangement. Making four provinces from the consideration of the distribution of fauna, Huxley divides the earth's surface as follows: Zoological Province
Geographical Equivalents 1. Omithogæa or Nova-Zelanian. New Zealand alonc.
Australia, Tasmania, and Negrito II. Antarctogæa or Australian
Islands. III. Dendrogæa or Austro-Columbian
South America, Central America,
((1) North America (N. of Mexico). IV. Arctogæa
(2) Africa (S. of Sahara). Having as sub-provinces (3) Hindostan.
(4) Europe, Asia (except India),
and Africa (N. of desert). The effect of this arrangement is to bring prominently into view the biological peculiarities of New Zealand, Australia, and South America, and to relate more nearly together those quarters of the globe (Europe, Asia, India, and Africa) which possess more features in common than the other and more specialised provinces. With all deference to such high authority as Professor Huxley in himself represents, one objection to his system of zoological geography may be found in the fact that the claims of New Zealand to rank as a distinct zoological region are highly debateable. Again, in the system propounded by Mr. Sclater, the geographical equivalents of Huxley's Arctogea are practically retained, and the not inconsiderable merit of simplicity, as well as considerations relating to the distinctness of the fauna, may weigh in the minds of naturalists as favouring the adoption of Mr. Sclater's provinces of distribution. These provinces or regions, depicted in Fig. 1, are as follows:
(includes Europe, Africa N. of the Desert, 1. Palæarctic Region
and Asia (except India and the Eastern
includes India and the Eastern Peninsula II. Oriental (or Indian) Region
and Archipelago to "Wallace's Line."
Australia, New Guinea, New Zealand, and III. Australian Region
Eastern Archipelago S. of “Wallace's
Line." IV. Ethiopian Region
Africa S. of the Desert, and Madagascar. V. Nearctic Region
North America, down to Central America.
South America, West Indian Islands, and VI. Neotropical Region
Southern Mexico. Beginning with the Palæarctic Region (Fig. 1), or the first of the six great provinces into which the biologist maps out the earth's surface, we may, in each case, firstly define the geographical boundaries of the province ; next note the leading groups of living beings which characterise the region ; and finally discuss its sub-regions wherever these latter present any features of striking interest. The constitution and limits of the Palæarctic Region introduce us at once to the revolution in geographical ideas which the study of distribution entails. We shall find therein a typical instance of that apparently arbitrary division of continents and piecing together of diverse lands, beneath which lies, in reality, the true relationship of the land areas of our globe. The Palæarctic Region of the biologist consists (1) of Europe in its entirety ; (2) Asia, except India and the Eastern Peninsula, along with as much of Africa as lies north of the desert. In the “mind's eye " we must, therefore, separate out the areas just mentioned from those with which, in ordinary geography, they are so intimately associated, and, piecing them together, form a great zoological province. This province is characterised, as are the other five divisions, by the possession of animals and plants which, for the most part, remain characteristic of its limits. Here and there we may detect a commingling with the forms of adjoining regions, and occasionally we may meet with a group which is common to two or more regions. Sometimes we see groups—such as the crows, swallows, owls, and pigeons among birds, or the rats and mice among quadrupeds—which have representatives in every region, and are thus cosmopolitan, or nearly so, in their distribution. But, apart from these exceptional instances, the main zoological and botanical features of each region are readily distinguishable; and no less so, as a rule, are the sub-regions into which each province is divided from considerations connected with the prevalence of special groups of animals in certain localities.
The quadrupeds of the Palæarctic Region include many familiar forms. As compared with the region most closely resembling itnamely, the Nearctic—this first region possesses a much greater variety of quadrupeds and birds. A very fair representation of all the higher animals is found in the Palæarctic province. With the