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 hicolor, 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 

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

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

 b}' any of the numerous skulls of P. oropldlus 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 premaxillee. The latter character is ai)proarhed 

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

 and deeper than in P. orophUus, 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. oropJiilus, 

 except that the anterior loop of the fi-ont 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. As a result the transverse loop is reduced 

 to a narrow crescent placed obliquely with the convexity directed for- 

 w^ard and outward. 



Meaaihremenis. — "Total length, about 118; tail vertebrae, 28; hind foot, 

 IS; ear from anterior root, 1)5 (from dry skin) " — Merriam. 



Genernl- re»iarl:s.— The type specimen of Fheyarom!/i< inteDnediin^, 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 preuiaxillas 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 othei- 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 chai'acter of the fur, but it api)ears 

 to be less dense and woolly than in /-". oropliilus. In color the type shows 

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

 brown instead of white. 



Phenacomys orophilus Merriam. 



Phenacoriu/s orophilus Merriam, North American Fauna, No. 5, p. 65, July 

 30, 1891. 



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

 7, 1894. 



Phenacomys orumontis Rhoads, American Naturalist, XXIX, p. 941, Octo- 

 ber, 1895. 



Tii}H' locaU/(/. —Siihnon River Mountains, Idaho (near head of Timber 

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



i->0. 31256J- 



Geographic distribution. — Hudsonian zone and parts of Canadian zone. 



