The geographical distribution of animals, with a study of the relations ...

chap, x.] THE PAL^ARCTIC REGION. 217extensive.The former is nearly 1,000 miles long, with a widthof from 200 to 350 miles, and isalmost as complete a desert asthe Sahara.With very few exceptions, this vast territory is exposed toan extreme climate, inimical to animal life.All the lower partsbeing situated to the north, have an excessively cold winter, sothat the limit of constantly frozen ground descends below theparallel of 60° north latitude. To the south, the land is greatlyelevated, and the climate extremely dry. In summer the heatis excessive, while the winter is almost as severe as furthernorth. The whole country, too, is subject to violent storms, bothin summer and winter ; and the rich vegetation that clothes thesteppes in spring, is soon parched up and replaced by dustyplains. Under these adverse influences we cannot expectanimal life to be so abundant as in those sub-regions subject tomore favourable physical conditions ;yet the country is so extensiveand so varied, that it does actually, as we shall see, possessa very considerable and interesting *auna.Mammalia.—Four genera seem to be absolutely confined tothis sub-region, Nectogak, a peculiar form of the mole family(TalpidaB) ; Poephagus, the yak, or hairy bison of Thibet ;withProcapra and Pantholops, Thibetan antelopes. Some othersmore especially belong here, although they justenter Europe, asSaiga, the Tartarian antelope ;Sminthus, a desert rat ;andEllobius, a burrowing mole-rat ; while Myospalax, a curiousrodent alliedand North China ;to the voles, is found only in the Altai mountainsand Moschus, the musk-deer, is almost confinedto this sub-region. Among the characteristic animals of theextreme north, are Mustela, and Martes, including the ermineand sable; Gulo, the glutton ; Tarandus, the reindeer; Myodcs,the lemming; with the lynx, arctic fox, and polar bear; andhere, in the Post-pliocene epoch, ranged the hairy rhinocerosand Siberian mammoth, whose entire bodies still remain preservedin the ice-cliffs near the mouths of the great rivers. Farthersouth, species of wild cat, bear, wolf, deer, and pika (Lagomys)abound ; while in the mountains we find wild goats and sheepof several species, and in the plains and deserts wild horsesVol. L—16