4 
362 ZOOLOGICAL GEOGRAPHY. [PART III. 
and Malaya to have taken place, we shall perhaps be able to 
agcount for most of the special affinities they present, with the 
least amount of simultaneous elevation of the ocean bed; which 
it must always be remembered, requires a corresponding de- 
pression elsewhere to balance it. 
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 ter- 
tiary period,—as shown by the abundant remains of mammalia 
wherever suitable deposits of Eocene age have been discovered,— 
proves, that an extensive Palzarctic 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 mamnialian remains with those of central and 
southern Europe, while closely allied forms of elephant, hyzena, 
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 Palearctic 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 Palarctic- 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 Palearctic faunas. The 
