MOUNTAIN MAMMALS 73 



the Marmot, another Rodent of the mountains, it 

 does not fall into a winter sleep, but continues making 

 tortuous burrows beneath the snow, mining its way 

 from root to root. The only special adaptation is a 

 storing habit, for in summer days it accumulates 

 provender in its nest, which is often found among 

 the loose debris of rocks. The store consists of 

 chopped grass, gentian roots, and similar hard fare, 

 the Snow Mouse being consistently vegetarian. There 

 are no other mammals at such altitudes, and birds-of- 

 prey are few, so that we may say that the Snow Mice 

 have found an asylum on the high Alps. But the life 

 is so penurious and exacting that we naturally look 

 for some explanation, and that is not in general terms 

 very difficult. Dr. Baumann points out that the Snow 

 Mouse was long ago one of the "tundra" animals 

 that flourished over a considerable part of Central 

 Europe during glacial and inter-glacial periods when 

 the uplands were covered by a great ice-sheet, now 

 encroaching and again receding. The bones of the 

 Snow Mouse are found in deposits belonging to that 

 " tundra " time along with those of Reindeer, Arctic 

 Fox, Mountain Hare, and Collared Lemming (Cuni- 

 culus torquatus). As the climate became milder 

 and the ice-sheet melted, the tundra-life became im- 

 possible. Some of the tundra animals, like the Rein- 

 deer and Arctic Fox, may have migrated northwards ; 

 the Snow Mouse went up the mountains, higher and 

 higher. This fits in well with the fact that the Snow 

 Mice occur to-day in scattered communities, separ- 

 ated by large mountainous tracts where there are 

 none of them. These scattered communities repre- 

 sent to some extent separate migrations from the low 



