522 bulletin: museum of comparative zoology, 



brilliant chestnut sides and grizzled dark back, with the progressive 

 disappearance of the uniform colors of the young, until finally, only 

 a patch on the forehead remains of the first coat. Other specimens 

 of equal size, taken at about the same time, seem to be acciuiring a 

 summer pelage in normal fashion, but may be animals born earlier 

 in the year, undergoing a second molt. 



Geographic distriJndion. — In general, this species is found on the 

 barrens of northern Alaska, including the peninsula and eastward 

 along the Arctic coast of Mackenzie to Coronation Gulf. Nelson 

 (1887, p. 278) found it from the mouth of Kuskoquim River, Bering 

 Sea, northward. He obtained a few at St. Michael's, Norton Sound, 

 and found it more plentiful about Bering Strait than at any other 

 place he visited. It occurs on the islands of the Strait and coastwise 

 to Point Barrow, and eastward. Nelson found it also on the Yukon 

 River, above Fort Yukon; at NuJato, Anook, and Kotlik along the 

 same river. There are specimens in the M. C. Z. from Herschel 

 Island, and from Baillie Island. The limits of its range to the north- 

 east are yet to be traced. It intergrades with the subspecies richard- 

 so7ii in Keewatin, and may be found eventually to intergrade to the 

 northeast with groenlandicus, though specimens are lacking to prove 

 this. In southwestern Alaska it is apparently rare. Osgood (1904, 

 p. 37) did not find it during the course of his investigations at the 

 base of the Alaska Peninsula, but he records specimens from Nusha- 

 gak, Bristol Bay, taken by McKay in 1881 to 1883. Still farther 

 south, and out on the peninsula itself, a specimen was taken at Chignik, 

 by Mr. J. T. Oliver in December, 1908 (U. S. Biol. Surv. 159,540). 

 It is immature and in process of acquiring the white winter pelage. 

 Anderson found it rare at IMuller Bay. The specimens available 

 are not sufficient to show whether these from more southern localities 

 differ from those to the north in color. 



Habits. — Writers on the natural history of Alaska agree in their 

 observations that this species is characteristic of the tundra and 

 barrens. Mr. Joseph Dixon, who obtained a fine series for the 

 M. C. Z. at Griffin Point, /Vrctic Alaska, found them wary, and usu- 

 ally well hidden, living under the snow till June, when the vegetation 

 starts. Toward spring they are likely to be found running about 

 on the top of the snow, much more so than Lemmus. Mr. Dixon 

 caught one on the ice at Demarcation Point on April 20, 1914, and 

 in the same month two others were caught two and a half miles 

 offshore on the ice. One killed June 5th at Griffin Point, had its 

 mouth full of feathers and bits of shavings for its nest. The young 



