STEPPES OF ASIA AND AMERICA 63 



so the upper parts of mountains form steppes because 

 the elevation prevents forest growth. Again, it is 

 beUeved that in those parts of the world recently sub- 

 jected to glaciation there was a period, after the retreat 

 of the ice, when the climate was unsuited to trees, lead- 

 ing to a wide extension of steppe conditions. This 

 brought in its turn a wide extension of steppe animals, 

 which, with the gradual improvement of the climate, and 

 the return of forest-haunting forms, were driven up 

 the moxintain sides to the Alpine regions. If this be so, 

 then the shrill whistle of the Alpine marmot, so common 

 a soimd in the mountainous regions of Switzerland in 

 summer, not only recalls the conditions of the Asiatic 

 steppes, but also brings back a time when much of 

 Europe was in the condition in which the steppes are 

 to-day. The Alpine marmot is now Hmited to the Alps, 

 Pyrenees, and Caucasus, the time being far past when 

 it also inhabited the low ground. On the other hand, 

 the bobac (A. bobac), the characteristic marmot of the 

 Asiatic steppes, extends into Europe as far as the 

 eastern frontier of Germany. 



Marmots are rather clumsy animals with heavy 

 bodies, short hmbs, and usually short tails. The short- 

 ness of the Hmbs must greatly limit the range of vision, 

 and the animals have very markedly developed that 

 habit of sitting up on the hind Hmbs to take a wider 

 view which is common in relatively short-legged animals. 

 The shortening of the fore-Hmbs here gives greater 

 purchase in burrowing, the burrows being extensive. 

 The food appears to be entirely vegetable, and the 

 animals hibernate much more profoundly than the 

 susliks. Bobacs occur in very large colonies, and 

 tunnel the ground in aU directions with their burrows. 

 According to Kobelt, the result of these excavations is 



