DIAGNOSES OF NEW NORTH AMERICAN MAMMALS. 



By Frederick W. True, 



Curator of the. Department of Mammals. 



In connection with certain studies of North American mammals 

 wiiich I have recently undertaken, I find it desirable to separate out a few 

 forms under new names. A mole from Fort Klamath, Oregon, presents 

 certain cranial and dental difterences from described species which seem 

 to me worthy of recognition, and I regard it necessary to jjlace Brew- 

 er's mole in a new genus. I desire in addition to publish diagnoses of 

 an undescribed race of Abert's squirrel, a new lemming, and a lemming- 

 like mouse, representing a new genus. 



SCIURUS ABERTI CONCOLOR, uew subspecies. 



Similar to aS'. aberti, but with no rufous area on the back, all the upper 

 surfaces being gray throughout. - Tail alike on both sides; the hair 

 annulated with gray and white proximally, with a rather broad subter- 

 minal black ring and pure white tips. Ears gray within; externally 

 gray and rufous, as in the typical form of S. aherti; furnished with 

 long terminal pencils, which are black, more or less mixed with gray 

 and rufous. Under surfaces of body and limbs pure white ; the hairs, 

 however, gray in the basil third, except on the under side of the front 

 legs, where they are Avhite to the base. Backs of feet gray; toes white. 



Dimensions (from the dry skin; type). — Head and body, 280 mm.; 

 tail vertebme, 215 mm.; ear from the occiput (without pencil), 22 mm.; 

 hind foot (without claw), 61 mm. 



Type. — No. fHs o U. S, II. M , female, Loveland, Larimer County, 

 Colo. Collected by William S. Smith. 



A male from the same locality is melanistic. All the melanistic spec- 

 imens of Abert's squirrel in the study collection of the National Museum 

 are from Colorado. 



The variety above described shows a remarkable resemblance to 

 Sciurusfossor, but the latter is without ear-tufts. 



Proceedings JSTatioual Museum, Vol. XVII— No. 999. 

 [Advance sheets of this paper were published April 2C, 1891. J 



Proc. N. M. 94 16 241 



