Osgood — Mammals From Mount McKinley. 61 



Sciurus hudsonicus Erxleben. 



RED SQUIRREL. 

 Common in all the timber. 



Citellus plesius ablusus Osgood. 



^ GROUND SQUIRREL. 



Eight specimens, mostly adults, from the base of the Muldrow Glacier 

 and the head of the Toklat River. These are typical examples of ablusus, 

 and thus carry its range considerably to the northeast, the nearest point 

 from which it was previously known being the head of Lake Clark. 



Marmota caligata (Eschscholtz). 



HOARY MARMOT. 



One specimen, a very fine old female, killed on the Peters Glacier, one 

 of the few good adults of this species now in collections from the interior 

 of Alaska. 



Castor canadensis Kuhl. 



BEAVER. 



Of rather rare occurrence, in interior ponds only. No specimens. 

 Evotomys dawsoni Merriam. 



DAWSON RED-BACKED MOUSE. 



Two specimens, both from the wooded region at the mouth of the Toklat. 



Microtus miurus oreas subsj). nov. 



T(/pe,{rova. head of Toklat River, Alaskan Range, Alaska. No. 148,596 

 U. S. National Museum, Biological Survey collection. (J* ad. August 8, 

 1906. C. Sheldon. Original No. 47. 



Cluiracters. — Similar to M. )niurus, but tone of color more ochraceous (not 

 so yellowish) throughout; tail slightly shorter and chiefly ochraceous, 

 slightly or not at all darker above than below. 



Color. — Type, in worn pelage: Upperparts and sides pale ochraceous 

 buff or clay color somewhat toned down on back by a slight mixture of 

 dusky and exposure of the plumbeous bases of the hairs ; underparts uni- 

 form pale ochraceous buff; feet creamy buff; tail pale ochraceous buff 

 with very faint traces of dusky on upper side. 



,SkidL — Very similar to that of J/, vdurus but somewhat narrower ; brain- 

 case more elongate ; zygomata less flaring anteriorly. 



Measurements. — Type and one topotype, repectively : Total length, 125, 

 120 > tail vertebrae, 20, 19 ; hind foot (dry), 19.2, 19. Skull of type : Basal 

 length, 26.7 ; basilar length, 23.9; mastoid width, 11.4; interorbital con- 

 striction, 3.4; nasals, 7.4; maxillary toothrow, 6. 



Remarks. — Seven specimens of this vole were secured in the high moun- 

 tain meadows near the head of the Toklat River. Two of these are adult 

 males and the remainder immatuie, but tlie entire series is characterized 



