80 Miller Synopsis of the Voles of the Genus Phenacomys. 



back and over lumbar region ; belly grayish white, the deep plumbeous 

 bases of the hairs showing through ; tail sharply bicolor, nearly black 

 above, white beneath ; feet light brownish ; whiskers mixed blackish 

 and silvery gray. 



Skull. The skull of the type and only known specimen of Phenacomys 

 intermedius is so badly broken that many of its characters cannot be ascer 

 tained. Enough remains to show two peculiarities which are not shared 

 by any of the numerous skulls of P. orophilus with which I have com 

 pared it. These are the great breadth of the interorbital region (4 mm. 

 at narrowest part of constriction) and the expanded terminations of the 

 ascending branches of the premaxillre. The latter character is approached 

 in the type specimen of P. preblei. The rostrum appears slightly shorter 

 and deeper than in P. orophilus, but this is probably only an optical effect 

 due to the imperfect condition of the nasal bones. 



Teeth. The enamel pattern is essentially the same as that of P. orophilus, 

 except that the anterior loop of the front lower molar is so deeply cut by 

 reentrant angles that a third outer triangle is wholly isolated and a fourth 

 inner triangle is nearly cut off. Asa result the transverse loop is reduced 

 to a narrow crescent placed obliquely with the convexity directed for 

 ward and outward. 



Measurements. "Total length, about 118; tail vertebra, 28; hind foot, 

 18 ; ear from anterior root, 13 (from dry skin) " Merriam. 



General remarks. The type specimen of Phenacomys intermedius, although 

 imperfect, shows too many differences from any of the other described 

 forms to be united with them. The breadth of the interorbital region is 

 a character of trifling importance, and one which might easily disappear 

 with increasing age, but the great expansion of the ascending branches 

 of the premaxillse is scarcely to be explained in this way. The peculi 

 arities of the front lower molar are not of a kind likely to be the result of 

 immaturity, and if they are purely individual they represent a degree of 

 variability far in excess of that presented by other known species of the 

 genus. As the skin is now sealed between two glass plates, it is not pos 

 sible to determine with certainty the character of the fur, but it appears 

 to be less dense and woolly than in P. orophilus. In color the type shows 

 no distinct differences from P. orophilus, except that the feet are light 

 brown instead of white. 



Phenacomys orophilus Merriam. 



Phenacomys orophilus Merriam, North American Fauna, No. 5, p. 65, July 



30, 1891. 

 Phenacomys truei Allen, Bull. Am. Mus. Nat. Hist., VI, p. 331, November 



Phenacomys oramontis Ehoads, American Naturalist, XXIX, p. 94] , Octo 

 ber, 1895. 



Type locality. Salmon River Mountains, Idaho (near head of Timber 

 Creek ; altitude, 10,500 feet). Type in U. S. National Museum (9 adult, 

 No. ffttf ). 



Geographic distribution. Hudsonian zone and parts of Canadian zone, 



