CHAP. VI. ] MAMMALIA OF THE OLD WORLD. 111 
the musk-sheep, and the woolly rhinoceros, are associated with 
several other species of rhinoceros and elephant; with nume- 
rous civets, now abundant only in warm countries; and with 
antelopes of several species. We also meet here with a great 
extension of range of forms now limited to small areas. The 
Saiga antelope of Eastern Europe occurs in France, where wild 
sheep and goats and the chamois were then found, together with 
several species of deer, of bear, and of hyzena. A few extinct 
genera even come down to this late period, such as the great 
sabre-toothed tiger, Machairodus ; Galeotherium, a form of Viver- 
ride; Paleospalax, allied to the mpl and Trogontherium, a 
Pe ntie form of beaver. 
We find then, that even at so early a stage of our inquiries we 
meet with a problem in distribution by no means easy to solve. 
How are we to explain the banishment from Europe in so short 
a space of time (geologically speaking) of so many forms of life 
now characteristic of warmer countries, and this too during a 
period when the climate of Central Europe was itself becoming 
warmer? Such a change must almost certainly have been due 
to changes of physical geography, which we shall be better able 
to understand when we have examined the preceding Pliocene 
period. We may here notice, however, that so far as we yet 
know, this great recent change in the character of the fauna is 
confined to the western part of the Palearctic region. In caves 
in the Altai Mountains examined by Prof. Brandt, a great col- 
lection of fossil bones was discovered. These comprised the 
Siberian rhinoceros and mammoth, and the cave hyzna; but all 
the others, more than thirty distinct species, are now living in 
or near the same regions. We may perhaps impute this dif- 
ference to the fact that the migration of Southern types into 
this part of Siberia was prevented by the great mountain and 
desert barrier of the Central Asiatic plateau ; whereas in Europe 
there was at this time a land connection with Africa. Post- 
pliocene deposits and caverns in Algeria have yielded remains 
resembling the more southern European types of the Post- 
pliocene period, but without any admixture of Arctic forms ; 
showing, as we might expect, that the glacial cold did not 
