218 ZOOLOGICAL GEOGRAPHY. [rART in. 



and asses, gazelles, two species of antelopes, flying squirrels 

 [Pteromys), ground squirrels (Tamias), marmots, of the genus 

 Spermophihis, with camels and dromedaries, probably natives 

 of the south-western part of this sub-region. The most 

 abundant and conspicuous of the mammalia are the great 

 herds of reindeer in the north, the wolves of the steppes, with 

 the wild horses, goats, sheep, and antelopes of the plateaus and 

 mountains. 



Among the curiosities of this sub-region we must notice the 

 seal, found in the inland and freshwater lake Baikal, at an eleva- 

 tion of about 2,000 feet above the sea. It is a species of Callo- 

 cephalus, closely allied to, if not identical with, one inhabiting 

 northern seas as well as the Caspian and Lake Aral. This 

 would indicate that almost all northern Asia was depressed 

 beneath the sea very recently ; and Mr. Belt's view, of the ice 

 during the glacial epoch having clammed up the rivers and con- 

 verted much of Siberia into a vast freshwater or brackish lake, 

 perhaps offers the best solution of the difficulty. 1 



Plate II. — Characteristic Mammalia of Western Tartary. — 

 Several of the most remarkable animals of the Pakearctic region 

 inhabit Western Tartary, and are common to the European and 

 Siberian sub-regions. We therefore choose this district for one 

 of our illustrative plates. The large animals in the centre are the 

 remarkable saiga antelopes (Saiga Tartarica), distinguished from 

 all others by a large and fleshy proboscis-like nose, which gives 

 them a singular appearance. They differ so much from all other 

 antelopes that they have been formed into a distinct family by 

 some naturalists, but are here referred to the great family Bovidas. 

 They inhabit the open plains from Poland to the Irtish Kiver 

 On the left is the mole-rat, or sand-rat (Spalax murinus). This 

 animal burrows under ground like a mole, feeding on bulbous 

 roots. It inhabits the same country as the saiga, but extends 

 farther south in Europe. On the right is a still more curious 

 animal, the desman (Myogalc Muscovitica), a long-snouted 

 water-mole. This creature is fifteen inches long, including the 

 tail ; it burrows in the banks of streams, feeding on insects, 



1 Quarterly Journal of the Geological Society, 1874, p. 494. 



