MURID^ 123 



angular process and condyle deep; molars prismatic, usually root- 

 less ; size usually small or medium, large in one genus. 



Genus Phenacomys Merriam. (Cheat — mouse.) 

 Skull strong and angular ; molars of young animals rootless, 

 those of adults rooted, strong, with sharp outer angles ; cusps of 

 lower molar largest on tongue side of teeth ; hasal part of lower 

 incisor passing l>eneath roots of lower molars; feet normal; tail 

 round, one third to one half the length of head and body; size 

 small. 



Phenacomys orophilus Merriam. (Mountain — loving.) 



MOUNTAIN LEMMING MOUSE. 



Above grayish brown, tinged with yellow in summer, thickly 

 sprinkled with black hairs; belly dirty white; feet whitish; tail 

 bicolor, mixed brown and white above, whitish below. 



Length about 145 mm. (5.70 inches); tail vertebrae 35 

 (1.38); hind foot 18 (.70). 



Type locality, Salmon River Mountains, Idalio. 



Higher parts of the mountains of British Columbia and 

 western United States south to Mount Shasta, where Walter K. 

 Fisher caught three "in the heather meadows along the upper 

 part of Squaw Creek." 



Phenacomys albipes Merriam. (White — foot.) 



REDWOOD LEMMING MOUSE. 



Above grizzled bistre with brownish wash on head, shoulders 

 and sides ; sides of nose dark grayish plumbeous with buffy wash ; 

 feet white ; ankles dusky ; tail bicolor, dusky above, whitish below. 



Length of type 168 mm. (6.60 inches) ; tail vertebrae 62 

 (2.45); hind foot 19 (.75). 



Type locality, redwoods near Areata, California. 



