Species of Akodon from Argentina. 335 
and its allies, rather coarsely lined on the back with the ends 
of the darker hairs. Under surface washed with pale drabby 
whitish, the bases of the hairs slate. Head uniform with 
back. Eyes with narrow buffy rims. Ears brown. Hands 
and feet dull whitish. Tail well-haired, bicolor, blackish 
brown above, dull whitish below, but the contrast not 
strongly marked. 
Skull of somewhat similar build to that of A. obseurus, 
stout, rather strongly bowed, with broad interorbital region, 
the edges of which are square but not beaded or ridged. 
Palatal foramina well open. Posterior nares narrow. In- 
cisors rather more turned back than usual, but there is some 
variation in this respect, the angle with the tooth-row in one 
specimen only 66°, while in others it rises to 74°, 75°, 79°, 
and 80°, a range of variation quite unusual; but the first 
specimen is probably abnormal. 
Dimensions of the type (measured in flesh) :— 
Head and body 116 mm.; tail 89; hind foot 23 (range 
from 20); ear 17. 
Skull: greatest length 29; condylo-incisive length 27° ; 
zygomatic breadth 15:2; nasals 10°7; interorbital breadth 5:1; 
breadth of brain-case 12°2; palatilar length 12°8 ; palatal 
foramina 7-2 ; post-foraminal palate 4:2 ; upper molar series 
(worn) 4°8. 
flab. Yacanto, near Villa Dolores, south-western slopes 
of the Sierra de Cordova. Alt. 900 m. 
Type. Old male. B.M. no. 16.1.6.38. Original number 
2536. Collected 19th November, 1915, by R. Kemp.  Pre- 
sented by Oldfield Thomas. Five specimens. 
This well-marked species looks as if it were allied to 
A, obscurus and lenguarum, but its incisors are markedly less 
thrown outwards. Its skull is perhaps most like that of 
A. varius, from which, however, as from all the others, it is 
readily distinguishable by its uniform pale brown colour. 
Akodon simulator, sp. n. 
Allied to A. varius, but with the coloration of members of 
the longipilis-hirtus group (genus Abrothriz of the succeeding 
paper). 
Size fairly large. Fur long, hairs of back about 9-10 mm. 
in length. General colour dark greyish, strongly suffused on 
the back with ‘clay-colour”’ ; head, shoulders, flanks, and 
hips slaty or purplish grey. Under surface washed with 
buffy or drabby whitish, the basal seven-eighths of the hairs 
dark slaty ; chin prominently contrasted white, the hairs 
9% 
ao 
