296 PROCEEDINGS OF THE ACADEMY OF [1899. 



M. cricetulus this angle is completely absent, no trace of it appear- 

 ing in any of the four specimens. The character, however, may 

 prove to be inconstant when large series of specimens are available 

 for comparison. 



Specimens examined. — Four, from the following localities in 

 Ladak : 



Banks of the Tso Kyun, Eupshu, 16,000 feet. 



Above Kiangchu Maidar, Rupshu. 



Rupshu, 16,000 feet. 



Measurements. — For measurements of Microtus cricetulus see 

 table, p. 298. 



Microtus acrophilus sp. nov. 



Tyjye adult ? (skin and skull) No. 62,162, United States 

 National Museum, collected on the Ladak side of the Kara 

 Korum Pass (altitude 17,000 feet) July 25, 1893, by Dr. W. L. 

 Abbott. 



General characters. — Closely related to Microtus stoliczlcanus 

 Blanford, but with shorter tail and much paler color. 



Fur and color. — Fur full and soft, about 15 mm. long on middle 

 of back. Basal two-thirds of hairs slaty plumbeous, shghtly paler 

 than in Microtus alhicauda and M. cricetulus. On the dorsal sur- 

 face the plumbeous basal area is followed by a broad band of 

 pinkish buff which gives the general tone to the pelage. Through- 

 out the dorsal surface the fur is sprinkled with longer dark brown 

 hairs, but these are nowhere conspicuous. The buff is brightest 

 on the head and lumbar region, paler and grayer across shoulders, 

 along sides and on rump. Belly snowy white, much clouded by the 

 plumbeous under fur. Feet and tail dirty white. 



Ears. — The ears are of about the same size as in M. cricetulus, 

 but owing to the longer surrounding fur they appear much shorter 

 and less conspicuous. 



Feet. — Palms 5-tuberculate ; soles 6-tuberculate. All tubercles 

 very large. Soles densely hairy behind tubercles. 



MammcB. — Mammae eight, four pectoral and four inguinal. 



Skull. — The skull of Microtus acrophilus is similar in general 

 form to that of M. alhicauda and M. cricetulus, but is slightly 

 larger than either, and much more massively built. Zygomatic 

 arches shorter, and rostrum broader and deeper than in M. albi- 



