Diagnosis. — Similar to Ochotona datiurica, Pallas, from the Mongolian Plateau, 

 but dorsal outline of skull less converse and audital bulloe slightly larger. 

 Differs from O. bed/ordi, Thomas, of Shensi and Shansi, in smaller 

 size (particularly of skull) more convex upper cranial outline, and much 

 smaller audital bulloe. 



Colour. — As in the related species the general colour is a light buff darkened by 

 a plentiful sprinkling of black hair tips, the buff everywhere predominat- 

 ing, and becoming clearer and more yellowish, along sides, particularly in 

 region of shoulder. A faintly indicated pale area between ear. Under- 

 parts and feet dull white with a slight buffy tinge ; throat crossed by a 

 broad band of dull buff, this area sometimes extends backward along 

 median line. 

 Ear with the usual dark marking on outer side. 



Measurements in mm. — Type : head and body, i8i ; hind foot, 29 (26) ;* ear 20 ; 

 skull, condylobasal length, 40*0 (42'4) ; zygomatic breadth, 20*4 (2i'2) ; 

 interorbital constriction, 4*2 (4*2) ; postorbital constriction, 13*2 (i3'8) ; 

 mastoid breadth including bulloe, 20*8 (20'o) ; depth of brain case at 

 middle, ii*o (ii'4) ; nasal, i5'o (i5"o) ; diastema, 9*8 (io"8) ; mandible, 

 27*2 (3o"2); maxillary tooth-row, alveoli, 7*4 (8"6) ; mandibular tooth-row, 

 alveoli, 7*4 (8'4), 



Specimens examined. — Seven, six from the type locality and one from Ts'ai-chia- 

 wei, 116 miles east of Lan-chou, Kansu (altitude 6300 ft.). This species 

 inhabits the deep loess gullies and ravines of central Kansu. Probably 

 common. Habits similar to those of 0. bed/ordi. Very shy and hard to 

 secure. 



* Measurements in parenthesis are those of an adult male Ochotona bedfordi from Wu-chai Hsien, Shansi (No. 172, 601). 



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