1904.] MOUSE- HARES OF THE GENUS OCHOTOXA. 207 



Key to the S'jJecies. 



A. Palatal and incisive foramina distinct. 

 «!. Ears small, 24 mm. or less. 



0(2. Colour of upper parts uniform dull rufous. 



«3. Large. Hind foot 35 mm O. alpina. 



63. Smaller. Hind foot 26 mm O.hyperborea. 



J2. Colour of upper parts white or yeUovrisli. 



a?. Ears rufous O. ladacensis. 



R Ears white O.ogotona. 



61. Ears large, 28 mm. Colour greyish ; head and shoulders 



rufous. 



a". Post-am-icular patch white O.rutila. 



h'. Post-auricular patch red (J. erythrotis. 



B. Palatal and incisive foramina mo^ distinct. 

 «!. Combined foramen narrowing in centre. 



a-. Colour of upper parts uniform. 



«3. Size large : colour white or yellowish O. koslowL 



&■*, Smaller: colour brown O.pusilla. 



b". Colour of upper parts not unifoi-m. 



a^. Colour brownish, with white collar behind ears O. rtifescens. 



£3. Colour greyish, with red head and shoulders in 



summer O. wardi. 



61. Combined foramen not nai-rowing in centre. 

 «2. Ears small, 23 mm. or less. 



«3. Size small. Hind foot 25 mm O.hodijsoni. 



63. Larger. Hind foot not less than 28 mm. 

 «•*. Colour light. 



«5. Mouth black O. melanostoma. 



65. Mouth white O.dcmrica. 



6*. Colour darker. 



aP. Uniform pale brown O. curzonice. 



V>. Dark brown, nifous on head and shoulders O. roylei. 



62. Ears large, 27 mm O. macrotis. 



OCHOTONA ALPIXA (Pall.). 



Lepus alpimcs Pallas, Glires, p. 52, pi. 2 (1778) ; id. Pteise, ii. 

 p. 701, tab. A (1773) ; Schreber, Saugthiere, iv. p. 911, pi. 238 

 (1792). 



Lagorays alpinus (Pall.) Cuvier, Eeg. Anim. p. 219 (1829); 

 Waterh. Mamm. ii. p. 15 (1848); Radde, Reisen >SUd. v. Ost- 

 Sibirien, i. p. 232 (1862). 



General colour of a uniform reddish brown, sometimes inclined 

 to greyish. Fur long, soft, .slate-grey at the base for about three- 

 foui'ths of its length, the terminal portion being greyish or whitish 

 with darker tip. Eai-s of moderate size, rounded, and thinly clad 

 with hairs similar in colour to the body-hairs. Under parts 

 imiform yellowdsh white, being sometimes rather more rufous 

 across the breast. 



The skull is stoutly built, but long and narrow. The incisive 

 foramiria are small and rounded, rather than narrow and elongate 

 as is the case with other species. The muzzle is broad and stout, 

 and the teeth large and .strong. 



Dimensions (approx. from skin). Head and body 175 mm.; 

 hind foot 35 ; ear 20. 



Skull. Greatest length 56 mm. ; basal length 46 ; zygomatic 

 breadth 25; length of nasals 18; leng-th of molar series 10; 

 interorbital breadth 6. 



Habitat. Originally described from specimens from the Altai. 



