1896.] NATUEAL SCIENCES OF PHILADELPHIA. 361 



ficulty in separating the Arctic species. * * * * We find Lepus 

 glacially inhabiting the most northern land yet visited, and attain- 

 ing its normal weight, eight to ten pounds, under apparently very 

 adverse circumstances. Still, I must say, it is sparsely diffused, and 

 we found that after killing a pair or two out of each valley that af- 

 forded any vegetation, the race seemed to be extirpated in that dis- 

 trict." 



Referring to the Alaskan Polar Hare, Lepus tscJmktschorvm, Mr. 

 E. W. Nelson says :'^ " The open country of the Yukon delta is 

 their place of greatest abundance, so far as I was able to learn. 

 There, in May, 1879, I found thern very common. The snow was 

 nearly gone, and while travelling along the small channels between 

 the islands, in the pale twilight which marks the nights at that sea- 

 son, we saw many hares playing about on the banks. They were 

 often in small parties of from three to five or six, and were not very 

 shy. * '1^ * While camped in this vicinity, at that time, I found 

 them to be almost entirely nocturnal in their habits, rarely moving 

 about in day-time, even during the gloomy days, when the sky was 

 obscured by dense, low lying clouds. Although they are nocturnal 

 in their habits, they see very well in the day, and it is extremely 

 difficult to surprise one in its form. Usually it spies the hunter be- 

 fore he gets within gunshot and leaves the spot in great haste. 



" During most of the year, these animals are essentially solitary, 

 but during April and May they gather into small parties, and some- 

 times as many as a dozen or more may be found on a single hill- 

 side." After declaring that he is sure this hare voluntarily takes to 

 the water, and crosses streams 30 yards in width in its wanderings, 

 Mr. Nelson continues : " In severe winter weather they seek the 

 shelter of willow or alder patches on the slopes of sheltered ravines, 

 or in other comfortable situations, but as a rule they are character- 

 istic of the open Arctic barrens, and on the wide expanse of deso- 

 late snow, their tracks are among the few evidences of life the trav- 

 eller finds in crossing the Alaskan tundras in winter." 



KEY TO SPECIES AND SUBSPECIES, 



Cranial characters. 



I. Upper and lower incisors strongly and regularly curved, meet- 

 ing within the arc of a circle mutually described by their ex- 



« Eep. Nat. Hist. Col. Alaska, 1887, pp. 271-273. 

 24 



