496 Mr. O. Thomas on small Mammals 
9. Akodon simulator, Thos. 
&. 326, 363, 377, 379, 381, 382 ; 2. 322, 368, 369. 
‘These specimens appear to agree absolutely with the type- 
series of simulator from Tucuman, and equally to differ from 
the Chumbicha glaucinus, to which they are geographically 
so much nearer. 
10. Akodon alterus, sp. n. 
&. 325, 327, 353, 359. 
Closely allied to A. spegazzini, but drabby brown instead 
of buffy olive. 
Size as in the allied species. General colour above drabby 
brown (between “ buffy brown” and “ Saccardo’s umber ” of 
Ridgway). Under surface dull soiled buffy throughout, the 
hairs broadly slaty at base, drabby or dull buffy terminally : 
hairs of inguinal region tipped with ochraceous, Ears 
coloured like head. Hands and feet dull drabby whitish ; 
claws of normal development, the anterior slightly shorter 
than the posterior. Tail of moderate length, blackish above, 
dull whitish below, the two colours gener rally well contrasted. 
Skull of the same narrow shape and with the same little 
swollen brain-case as in A. speguzzinii, this narrowness of 
skull distinguishing the two species from the members of the 
arenicola group. Lye gomatic plate well projected forward, its 
anterior edge often tending to be slightly concave. Palatal 
foramina very long, reaching to thie level of the second 
re-entrant angle on the inner side of m*. Bulle of normal 
size. 
Molars narrow, early worn down, those of the youngest 
specimen too worn to say if a detinite anterior notch is or is 
not present on m'. 
Dimensions of the type:— 
Head and body 83 mm.; tail 68 ; hind foot 20; ear 14. 
Skull: greatest length 25; condylo-incisive length 23°5 ; 
zygomatic breadth 12 Ge nae 9:4; interorbital breadth 46; 
breadth of brain-case 11; palatilar length 10°4 ; palatal 
foramina 6°3 ; postforaminal palate 2°9 ; upper molar 
series 4°3. 
Hab. (of type) asabove. Other specimens from Chumbicha, 
Type. Adult male. B.M. no, 19. 2.7.44. Original 
number 359. Collected 6th September, 1918. 
A. spegazzinii was described on a specimen from Cachi 
skinned out of spirit, and the coloration therefore could not 
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