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. bedfordi, 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, i3'2 (i3'8) ; 

 mastoid breadth including bulloe, 20'8 (200) ; depth of brain case at 

 middle, ii'o (li"4) ; nasal, 15-0 (i5'o) ; diastema, 98 (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. bedfordi. Very shy and hard to 

 secure. 



Measaremencs id parenthesis aie those of an adult male Ockolona bedfordi fiom Wu-cfaai H&ien, Shansi (No. 173, 601). 



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