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

216 ZOOLOGICAL GEOGRAPHY. [part hi.Ill— The Siberian Sub-region, or Northern Asia.This large and comparatively little-known subdivision of thePalrearctic region, extends from the Caspian Sea to Kamschatkaand Behring's Straits, a distance of about 4,000 miles ; andfrom the shores of the Arctic Ocean tothe high Himalayas ofSikhim in North Latitude 29°, on the same parallel as Delhi.To the east of the Caspian Sea and the Ural Mountains is a greatextent of lowland which is continued round the northern coast,becoming narrower as it approaches the East Cape. Beyondthis, in a general E.KE. direction, rise hills and uplands, soonbecoming lofty mountains, which extend in an unbroken linefrom the Hindu Koosh, through the Thian Shan, Altai andYablonoi Mountains, to theextremity of Asia.Stanovoi range in the north-easternSouth of this region is a great central basin,which is almost wholly desert ; beyond which again is the vastplateau of Thibet, with the Kuenlun, Karakorum, and Himalayansnow-capped ranges, formingdistrict on the globe.the most extensive elevatedThe superficial aspects of this vast territory, as determined byits vegetable covering, are very striking and well contrasted. Abroad tract on the northern coast, varying from 150 to 300 andeven 500 miles wide, is occupied by the Tundras or barrens,where nothing grows but mosses and the dwarfest Arctic plants,and where the ground is permanently frozen to a great depth.This tract has its greatest southern extension between the riversObi and Yenesi, where it reaches the parallel of 60° north latitude.Next to this comes a vast extent of northern forests,mostly of conifers in the more northern and lofty situations,while deciduous trees preponderate in the southern portions andin the more sheltered valleys. The greatest extension of thisforest region is north of Lake Baikal, where it is more than1,200 miles wide. These forests extend along the mountainranges to join those of the Hindu Koosh. South of the foreststhe remainder of the sub-region consists of open pasture-landsand vast intervening deserts, of which the Gobi, and those ofTurkestan between the Aral and Balkash lakes, are the most