The Geographical Distribution of Animals, Volume 1 / 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

Concluding Remarks on the Oriental Region.—We have already so fully discussed the internal and external relations of the several sub-regions, that little more need be said. The rich and varied fauna which inhabited Europe at the dawn of the tertiary period,—as shown by the abundant remains of mammalia wherever suitable deposits of Eocene age have been discovered,—proves, that an extensive Palæarctic continent then existed; and the character of the flora and fauna of the Eocene deposits is so completely tropical, that we may be sure there was then no barrier of climate between it and the Oriental region. At that early period the northern plains of Asia were probably under water, while the great Thibetan plateau and the Himalayan range, had not risen to more than a moderate height, and would have supported a luxuriant sub-tropical flora and fauna. The Upper Miocene deposits of northern and central India, and Burmah, agree in their mammalian remains with those of central and southern Europe, while closely allied forms of elephant, hyæna, tapir, rhinoceros, and Chalicotherium have occurred in North China; leading us to conclude that one great fauna then extended over much of the Oriental and Palæarctic regions. Perim island at the mouth of the Red Sea, where similar remains are found, probably shows the southern boundary of this part of the old Palæarctic region in the Miocene period. Towards the equator there would, of course, be some peculiar groups; but we can hardly doubt, that, in that wonderful time when even the lands that stretched out furthest towards the pole, supported a luxuriant forest vegetation, substantially one fauna ranged over the whole of the great eastern continent of the northern hemisphere. During the Pliocene period, however, a progressive change went on which resulted in the complete differentiation of the Oriental and Palæarctic faunas. The causes of this change were of two kinds. There was a great geographical and physical revolution effected by the elevation of the Himalayas and the Thibetan plateau, and, probably at the same time, the northward extension of the great Siberian plains. This alone would produce an enormous change of climate in all the extra-tropical part of Asia, and inevitably lead to a segregation of the old fauna into tropical and temperate, and a modification of the latter so as to enable it to support a climate far more severe than it had previously known. But it is almost certain that, concurrently with this, there was a change going on of a cosmical nature, leading to an alteration of the climate of the northern hemisphere from equable to extreme, and culminating in that period of excessive cold which drove the last remnants of the old sub-tropical fauna beyond the limits of the Palæarctic region. From that time, the Oriental and the Ethiopian regions alone contained the descendants of many of the most remarkable types which had previously flourished over all Europe and Asia; but the early history of these two regions, and the peculiar equatorial types developed in each, sufficiently separate them, as we have already shown. The Malayan sub-region is that in which characteristic Oriental types are now best developed, and where the fundamental contrast of the Oriental, as compared with the Ethiopian and Palæarctic regions, is most distinctly visible.

TABLES OF DISTRIBUTION.

In constructing these tables, showing the distribution of various classes of animals in the Oriental region, the following sources of information have been chiefly relied on, in addition to the general treatises, monographs, catalogues, &c., used for the compilation of the Fourth Part of this work.

Mammalia.—Jerdon's Indian Mammalia; Kelaart's Fauna of Ceylon; Horsfield and Moore's Catalogue of the East India Museum; Swinhoe's Catalogue of Chinese Mammalia; S. Müller's Zoology of the Indian Archipelago; Dr. J. E. Gray's list of Mammalia of the Malay Archipelago (Voyage of Samarang); and papers by Anderson, Blyth, Cantor, Gray, Peters, Swinhoe, &c.

Birds.—Jerdon's Birds of India; Horsfield and Moore's Catalogue; Holdsworth's list of Ceylon Birds; Schlegel's Catalogue of the Leyden Museum; Swinhoe on the Birds of China, Formosa, and Hainan; Salvadori on the Birds of Borneo; Lord Walden on the Birds of the Philippine Islands; and papers by Blyth, Blanford, Elwes, Elliot, Stoliczka, Sclater, Sharpe, Swinhoe, Verreaux, and Lord Walden.

Reptiles.—Günther's Reptiles of British India; papers by same author, and by Dr. Stoliczka.

TABLE I.

FAMILIES OF ANIMALS INHABITING THE ORIENTAL REGION.

Explanation.

Names in italics show families peculiar to the region.