1899.] NATURAL SCIENCES OF PHILADELPHIA. 287 



Measurements. — The niea,suremeuts of four adult specimeus of 

 Microtus ravidulm are given in the following table: 



Measurements of Microtus ravklulus. 



Okchi, valley of the Aksai 



eastern Turkestan 



Okchi, valley of the Aksai, 



eastern Turkestan 



Okchi, valley of the Aksai, 



eastern Tvirkestan 



Okchi, valley of the Aksai, 



eastern Turkestan 



62,157 

 62,158 

 62,159*i 9 

 62,160 j 9 



d" 



Microtus pamirensis sp- nov. 



%je adult cj" (skin and skull), No. 62,161, United States 

 National Museum, collected at Tagdumbash, Pamir (altitude 

 12,000 feet), June 18, 1894, by Dr. ^Y. L. Abbott. 



General characters. — Size medium; tail short; ears moderate, 

 scarcely overtopping fur; color uniform pale brown above, whitish 

 below; skull heavily built and angular; upper incisors conspicu- 

 ously protruding ; two anterior triangles in first lower molar open ; 

 posterior loop of back upper molar nearly straight. 



Fur and color. — The fur is full and soft, that on middle of back 

 about 12 mm. in length. It is everywhere slategray at base. 



Color of dorsal surface light broccolibrown, very uniform and 

 only inconspicuously sprinkled with darker hairs. Ventral surface 

 grayish white, strongly clouded anteriorly by the dark bases of the 

 hairs. Feet whitish. Tail whitish with a very inconspicuous 

 dusky dorsal stripe. 



Feet. — The soles and palms were slit open by the collector, so 

 that it is impossible to determine the number and position of the 

 tubercles. Claws as in typical members of the subgenus Microtus. 



Skull. — The skull of Microtus pamirensis is unlike that of any 

 other true Microtus with which I am acquainted. In superficial 



Collector's measurement. 



Type. 



