242 Mr. O. Thomas on Neotropical Mammals. 
comparatively short. Hinder edge of palate some distance 
behind last molar. Molars small and light. 
Dimensions of the type, measured in the flesh :— 
Head and body 110 millim.; tail 77; hind foot, s. u. 22, 
c.u. 24; ear 14. 
Skull: greatest length 27°5 ; basilar length 21°3; greatest 
breadth 14; nasals 11; interorbital breadth 4°8; breadth of 
brain-case 12°2; palate length 11:2; diastema 7; palatal 
foramina 6°1; length of upper molar series 3°4. 
Hab. Valle del Lago Blanco, Southern Chubut (Cordillera 
region). 
Syne Male. Original number XVI. Collected 6th 
August, 1900, by Mr. J. Koslowsky. About forty specimens 
examined. 
Akodon (Chelemys, subg. 1.) vestetus, sp. ne 
[CHELEMYS*, subg. n. 
General characters, skull, and dentition as in Akodon, but 
the claws, especially the anterior ones, very large, fossorial. 
Type, Akodon megalonyx, Waterh. 
Now that the known species have been so considerably 
multiplied, it seems convenient to have a subgeneric name 
by which to designate what have been hitherto termed the 
“ Jong-clawed Akodons.”’] 
General appearance and proportions very much as in 
A. (C.) macronyx, Thos., but colour darker, tail more 
distinctly bicolor, and skull broader and flatter. 
Fur very long, close, and woolly ; hairs of back about 
10-11 millim. in length. General colour above darker 
than in A. macronyz, approximately resembling Ridgway’s 
“ sepia”’ or “olive.” Sides paler, approaching ‘ broccoli- 
brown.” Underparts dull white, well defined on the sides 
for such a thick-furred animal, the slaty bases to the hairs 
showing through. lars short, scarcely projecting above the 
fur, well-haired, brown. Arms and inner sides of legs 
greyish white; hands and feet wholly white. ‘Tail well- 
haired, distinctly and sharply bicolor, dark brown above, 
white below. 
Skull, as compared with that of A. macronyx, broader, 
more flattened, and less cylindrical, with more widely ex- 
panded zygomata; interparietal rather smaller. ‘Teeth as in 
the allied species. 
* xnAn, a hoof or claw. 
