468 Mr. O. Thomas on new Peruvian Species of 



in the more typical Phyllotes, their anterior halves externally 

 brown, rather darker than the general head-colour; hairs 

 on their inner surface yellowish, an ill-defined patch of 

 yellowish fawn at their bases. Under surface white, not very 

 sharply defined, the bases of the hairs slate. Upper surface 

 of hands and feet silvery white. Tail only about half the 

 length of the head and body, uniformly finely haired, not 

 pencilled ; a narrow line along the top ill-defined fawn, the 

 remainder white. 



Skull more normal in general shape than the widely 

 expanded skull of Ph. boliviensis or the very peculiar one of 

 Ph. Garleppi. Nasals narrow, evenly tapering backwards, 

 considerably surpassing the premaxillary processes posteriorly. 

 Interorbital region flat, its edges square but not ridged. 

 Interparietal narrow, strap-like, its anterior edge concave 

 forwards. Anterior zygoma-root slanted backwards. Palatal 

 foramina long; choanse narrow; bullte small, much smaller 

 than in Ph. boliviensis. Molars normal. Incisors narrow, 

 though not so much so as in Ph. Garleppi; pale yellow 

 above and below. 



Dimensions of the type (measured in the flesh) : — 



Head and body 105 millim. ; tail 54 ; hind foot (s. u.) 21*5, 

 (c. u.) 23; ear 23. 



Skull : greatest length 253 ; basilar length 20'2 ; greatest 

 breadth 14'5 ; nasals 10x3*6; interorbital breadth 3"7; 

 breadth of brain-case 12"5 ; palate length 12*1 ; diastema 6 - 9 ; 

 palatal foramina 6 ; length of upper molar series 4*7. 



Hab. Binconado Malo pass, above Caylloma, on the Sumbay 

 road, Peru. Altitude 5500 metres (nearly 18,000 feet). 



Type. Female. B.M. no. 0. 10. 1. 60. Original number 

 1104. Collected 18th June, 1900, by Mr. P. O. Simons. 

 Nine specimens examined, all dug out of one burrow. 



This most interesting little mouse lives at the highest alti- 

 tude from which mammalian life has been recorded in the 

 New World, and in the Old is only surpassed in this respect 

 by a few of the Himalayan species. Zoologically it is also 

 of interest, owing to its forming a link between the peculiar 

 short-tailed Phyllotis Garleppi* and the other members of 

 the genus, so that it tends to resolve the doubt with which I 

 assigned that species to Phyllotis. 



Akodon amcenus, sp. n. 



A medium-sized species with close fur and sharp-edged 

 supraorbital rogion. 



* Ann. & Mag. Nat. Hist. (7) i. p. 279 (1898). 



