182 Mr. Q. Thomas on new 
Thos., but differs by its larger and darker-coloured ears, 
smaller palatal foramina, and smaller molars. 
Eliymodontia ducilla, sp. n. 
An Eligmodontia of the short-tailed group, with a striking 
superficial resemblance to Phyllotis sublimis, though smaller 
and with shorter fur. 
Size small, about as in FZ. lepida, laucha, &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, 
sandy white above, clear white below. 
Skull with the nasals and premaxillary processes of equal 
extension backwards ; interorbital space narrow, more parallel- 
sided than in #. laucha; interparietal broad, strap-like, 
narrow antero-posteriorly, its lateral parts as broad as the 
centre; palatal foramina long, extending to the second lamina 
ofm.’. ‘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 73 millim.; tail 30; hind foot, s. u. 17, 
eye ho sear 17. 
Skull: greatest length 21°7; basilar length 18°5; greatest 
breadth 12; nasals, length 8; interorbital breadth 3:5; 
breadth of brain-case 10°4; diastema 5:13; palate from hen- 
selion 9°8; palatal foramina 5; length of upper molar 
series 3°7. 
Hab. San Anton, Lake Titicaca, 8.E. Peru. Alt. 3800 m. 
Type. Female. B.M. no. 1. 1. 1. 1. Original number 
1118. Collected 28th June, 1900, by Mr. P. O. Simons. 
This pretty little mouse is most nearly allied to 4. lepida 
and sorelia, 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 
wight be taken for a smaller shorter-haired subspecies of that 
animal. 
