524 bulletin: museum of comparative zoology. 



the Dicrostonyx of Greenland. The rudimentary thumb that he 

 mentions, is further characteristic of the genus. Since the descrip- 

 tion appHes well to this animal and there is no other species known 

 that "burrows in the turfy soil" of the shores of Bering Strait which 

 it could possibly fit, the name must inevitably replace nelsoni. 



Recent writers have regarded this as a subspecies of D. hudsonms, 

 but in its tooth-pattern, coloration, and geographic distribution, it is 

 quite distinct and is fully entitled to rank as a separate species. 

 The possibility of intergradation with groenlmidicus, however, is not 

 to be overlooked, though this point cannot be settled until more 

 and better material from the Arctic Archipelago is available. Equally 

 uncertain is its relationship to the Old World lemmings of eastern 

 Asia. A single specimen, A. M. N. H. 1<S,590, from Gichiga, on the 

 Okhotsk Sea, is similar in color to some Alaskan summer skins, but 

 is more ochraceous over the shoulders and back, with a yellowish 

 appearance in contrast to the dark red of rubricatusl No doubt 

 the two are closely allied and have been separated for no very long 

 period geologically. 



Spccimeyis examined. — A total of 152 from the following locali- 

 ties : — 



Alaska. 



"Alaska," 3 (Univ. of Cal.). 



Muller Bay, Alaska Pen., 1 (A. M. N. H.). 



Chignik, Alaska Pen., 1 (U. S. Biol. Surv.). 



Yukon River, Russian Mission, 1 (Univ. of Cal.). 



Lower Yukon, 2 (U. S. N. M.). 



Near St. Michael's, 1 (Univ. of Cal.). 



St. Michael's, 6 (U. S. N. M.). 



Sledge Island, 4 (U. S. N. M.). 



Point Barrow, 6 (M. C. Z.); 5 (A. M. N. H.); 15 (U. S. Biol. Surv.); 



6 (Field Mus.); 10 (U. S. N. M.). 

 Flaxman Island (A. M. N. H.). 

 Griffin Point, 52 (M. C. Z.). 

 Point Humphreys, 2 (M. C. Z.). 

 Demarcation Point, 2 (M. C. Z.). 

 Ft. Yukon, 2 (U. S. N. M.). 

 Ft. Davis, 1 (A.M.N. H.). . 

 Herschel Island, 1 (M. C. Z.); 8 (A. M. N. H.). 

 Porcupine River, 200 miles above Yukon, 1 (U. S. N. M.). 



Mackenzie. 



Arctic Coast, 2 (M. C. Z.). 

 Barren Grounds, 1 (U. S. N. M.). 



