Synopsis of tJte Voles of the Genus Phenacomys. 79 



Genus PHENACOMYS Merriam. 



Phenacomys Merriam, North American Fauna, No. 2, p. 28, October 30, 

 1889. 



Type species. Phenacomys intermedium Merriam. 



Geographic distribution. Boreal North America from Atlantic to Pacific, 

 south to the Gulf of Saint Lawrence, the north shore of Lake Superior, 

 the coast of Oregon, and in the Rocky Mountains to Colorado. 



Generic characters. Skull and teeth in general as in Microtus, but molars 

 distinctly two-rooted in the adult, and root of lower incisor never reach 

 ing level of dental foramen. Reentrant angles on inner side of lower 

 molars very much deeper than those of outer side, not approximately 

 equal to outer angles as in Microtus and Evotomys. 



Remarks. Phenacomys combines the palate, heavily built angular skull, 

 and strong sharply angled teeth of Microtus with the rooted molars and 

 short lower incisors of Evotomys. It differs from both Microtus and 

 Evotomys in the relatively great depth of the inner reentrant angles of 

 the mandibular molars. 



KEY TO THE SPECIES OP PHENACOMYS. 



Tail about 40 percent of total length . .longicaudus. 



Tail about 25 percent of total length. 



Face and muzzle reddish or yellowish in strong contrast 

 with rest of head. 



Skull of adult with deep frontal sulcus ungava. 



Skull of adult without frontal sulcus latimanus. 



Face and muzzle essentially same color as rest of head. 



Ascending branches of premaxillae broad intermedius. 



Ascending branches of premaxillse narrow. 



Color decidedly ochraceous preblei. 



Color gray ... orophilus. 



Phenacomys intermedius Merriam. 



Phenacomys intermedius Merriam, North American Fauna, No. 2, p. 32, 

 October 30, 1889. 



Type locality. Basaltic plateau about 20 miles NNW. of Kamloops, 

 British Columbia. Altitude 5,500 feet. Type No. 780, Mus. Geol. and 

 Nat Hist. Surv. Canada. Collected by Dr. Geo. M. Dawson. 



Geographic distribution. Phenacomys intermedius is known from the type 

 locality only. 



General characters. Size small; general color pale; feet light brown; 

 skull with interorbital region and ascending branches of premaxillse very 

 broad ; front lower molar with five well developed salient angles on outer 

 side. 



Color. Back grizzled grayish brown with a yellowish tinge, everywhere 

 sprinkled with black-tipped hairs which are most numerous on middle of 



