55^ Bulletin American Museum of Natural History. [Vol. XIX, 



25. Lemmus helvolus (Ricliardson). GOLDEN LEMMING. 



This beautiful lemming is represented by 43 specimens, col- 

 lected as follows: Telegraph Creek, 28 specimens, July 31, 

 August 9, and October 17; Level Mountain, n, September 

 10-25; Shesley River, i, August 27; Raspberry Creek, i, 

 October 1 1 ; and 2 without locality. Only about 1 2 are adult, 

 the others ranging from nursing young to two-thirds grown. 



In the adults the anterior half of the upper surface is gray 

 suffused with fulvous, the sides and top of the head and neck 

 being gray or grayish, gradually passing into deep yellowish 

 brown over the shoulders, and thence posteriorly to the tail 

 the color "ranges, in different specimens, from ochraceous, or 

 even golden, to ochraceous rufous, and in some to reddish 

 chestnut. (Late September and October specimens have the 

 upper parts lighter or more golden than the August examples.) 

 The flanks are deep ochraceous, varying to orange ochraceous; 

 chin and throat soiled grayish white ; rest of the ventral sur- 

 face ranging in different specimens from deep buff to ochra- 

 ceous buff. In the half to two-thirds-grown young the head is 

 more heavily suffused with fulvous than in adults, and there 

 is hence less contrast between the anterior and the posterior 

 parts of the dorsal area. Young in the soft, woolly, first 

 pelage are dull brown strongly washed with dark rufous, with 

 nearly the same contrast in color antero-posteriorly as in the 

 adults. In all pelages there is a slight admixture of stiff 

 black or blackish -tipped hairs overtopping the general pelage, 

 varying greatly in abundance in different individuals that are 

 comparable as to season and age. 



This species, like most microtines, begins to breed at an 

 early age, and greatly increases in size after birth of the first 

 young. The largest specimens (5 males and 3 females) of the 

 series, apparently all entitled to be classed as adult, measure 

 as follows: Total length, 143.6 (134-150); tail vertebrae, 

 22.3 (20-25); hind foot, 19.9 (18.5-22); ear, 11.5 (10-13). 

 Three additional females that appear to have suckled young 

 range in total length from 124129, with the other measure- 

 ments proportional. 



