No. II. MAMMALIA. 203 



characters of this lemming. 1 He was able to show that the 

 extraordinary development of the claws of the fore-feet which 

 is sometimes observed, is not a specific character, nor due to 

 age or sex, but he could not determine whether it was 

 seasonal, as specimens with such claws were known in both 

 winter and summer coats. The series which I collected in 

 Grinnell Land enables me to determine this point. The 

 strap-like development of the claws persists in these latitudes 

 during the greater part of the year, while the ground is 

 covered with snow, and is thus retained for some time after 

 the animal has put on the summer livery. But by the end of 

 summer, when large areas are bared of snow, the claws are worn 

 down to an ordinary size and become pointed. This seasonal 

 development is, in fact, analogous to what we find in some of 

 the northern Tetraonidce. The food of this lemming consists 

 of vegetable substances, especially the buds of Saxifraga 

 oppositifolia. It makes nests of grass in the snow, which we 

 often found during summer as the snow thawed ; in most 

 cases large accumulations of the dung of these animals were 

 lying close to the nests. I see no reason to suppose that this 

 animal hybernates, for on the return of light, with a tem- 

 perature at minus 50 and a deep mantle of snow covering 

 the land, the lemming was to be seen on the surface of the 

 snow, close to its burrow, blinking at the first rays of the 

 sun ; and during the depths of winter there could be no 

 greater difficulty in procuring food than in February. At 

 that season of the year I found the stomach of the lem- 

 ming filled with green buds of saxifrage, which had been 

 gathered from under the snow. Sometimes I came across 

 the lemming at some distance from the hole by which it 

 retreats to its galleries under the snow, and it was interest- 

 ing to see the speed with which it could disappear, 

 throwing itself on its head, its fore-paws worked with great 

 rapidity, rotating outwards, and throwing up a cloud of 

 snow-dust some six inches high. Later on in the year I 



1 < Reise Sibir./ II. Th. 2, pp. 87-99, pis. IV.-VII. 



