182 Mr. U. Tliomas on new 



Thos., but differs by its larger and darker-coloured ears, 

 smaller palatal foramina, and smaller molars. 



Eliyvwdontia ducilla, sp. n. 



An Eligmodontia of tlie short-tailed group, with a striking 

 superficial resemblance to Phyllotis snblimis, though smaller 

 and with shorter fur. 



Size small, about as in E. lepida, laucka, &c. Fur very 

 soft, fairly long; hairs of back about 8 millim. in length. 

 General colour above pale greyish fawn, finely grizzled with 

 brown ; nearly uniform in tone from head to rump, but the 

 centre of the back rather darker. Sides of nose and an indis- 

 tinct line running along the flanks edging the belly-colour 

 pale sandy fawn. Under surface white, not sharply defined 

 laterally, the hairs grey basally, white terminally. Ears of 

 medium length, pale brown ; a whitish spot on the head 

 behind them, as in other species of the group. Hands and 

 feet white above ; soles hairy posteriorly. Tail less than 

 half the length of the head and body, well clothed with hairs, 

 handy white above, clear white below. 



Skull with the nasals and preniaxillary processes of equal 

 extension backwards ; interorbital sj^ace narrow, more parallel- 

 sided than in E. Jaucha \ interparietal broad, strap-like, 

 narrow antero-posteriorly, its lateral parts as broad as the 

 centre; palatal foramina long, extending to the second lamina 

 of w?.\ Teeth of the complicated brachyodont character found 

 in E. laucha and its allies, very different to those of Phyllotis, 

 which are of a more simple, though semi-hypsodont and 

 zigzag, pattern. 



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



Head and body I'd millim.; tail 30; hind foot, s. u. 17, 

 c. u. 18 ; ear 17. 



Skull : greatest length 21*7 ; basilar length 18*5; greatest 

 breadth 12; nasals, length 8; interorbital breadth o'O] 

 breadth of brain-case 10*4; diastema O'l ; palate from hen- 

 selion 9*8 ; palatal foramina 5 ; length of upper molar 

 series 3*7. 



Eab. San Anton, Lake Titicaca, S.E. Peru. Alt. 3800 m. 



2ype. Female. B.M. no. 1. 1. 1. 1. Original number 

 1118. Collected 28tb June, 1900, by Mr. P. O. Simons. 



This pretty little mouse is most nearly allied to E. lepida 

 and aorel/a. but may be readily distinguished from both by 

 its much paler and more fawny colour. Its superficial resem- 

 blance to Phyllotis sublimis is so great that at first sight it 

 might be taken for a smaller shorter-haired subspecies of that 

 animal. 



