228 IMr. O. Tliomas on 



nientup, so tliat in these animals tliere may be said to be a 

 second articulation between the mandible and cranium. 



13. Ctenoviys f rater, sp. n. 



a,h. c? ? . Potosi, 4300 m. 28th September, 1901. 



Size medium, decidedly smaller than in C. opimus, the 

 common species of the district. General colour brownish 

 fawn, rather browner than Hideaway's " fawn-colour." 

 Under surface dull buffy, without white patches, the inguinal 

 region with a tinge of rufous ; line of demarcation on sides 

 not defined. Muzzle and chin blackish. No darker markings 

 on or around ears. Hands and feet thinly haired, pale 

 brownish. Tail very finely liaired (almost naked in the 

 type), brown above, whitish beneath and at the end. 



Skull short and stumpy, high, with its profile flat from the 

 middle of the nasals to the middle of the parietals, and then 

 markedly and unusually convex, the posterior half of the 

 brain-case bent downwards. Nasals short, broad, broadest 

 at their middle, narrowing both forwards and backwards, 

 scarcely surpassed posteriorly by the premaxillary processes. 

 Interorbital region flat, its edges sharply cut, with quite 

 rudimentary postorbital processes. A narrow longitudinal 

 median fontanelle present in both specimens at the hinder end 

 of the frontals. Bullae very peculiarly shaped, narrow, little 

 inflated, their outline slightly concave forwards; their l)ony 

 meatus very long and slender (see measures below). Ecto- 

 condylar process of lower jaw small, inconspicuous. 



Incisors broad and heavy, their combined breadth 7*3 

 millim., dark orange above and below. Molars with the 

 usual antero-external and posterior gaps in their enamel enve- 

 loj)e more extended than in C. opimus^ less than in some of 

 the smaller species. 



Dimensions of the type : — 



Head and body 180 millim.; tail 73; hind foot, s. u. 35, 

 c. u. 39 ; ear 9. 



Skull : greatest length in middle line, excluding incisors, 

 •16; basilar length 38; greatest breadth 31; nasals 17x8; 

 interorbital breadth 10"5 ; least breadth across brain-case 

 19; ])Osterior breadth on meatus 30"5 ; palate length 21; 

 diastema 125; bulla, greatest diagonal diameter 15*5, lesser 

 diameter at right angles to last 6"G ; tip of meatus to postero- 

 internal side of bulla 12"3 ; up|)er tooth-series (alveoli) 10*7. 

 Lower jaw, gieatest breadth 40. 



llah. as above. 



Tijije. Adult female. B.M. no. 2. 2. 2. 113. Original 



