214 On new Argentine Species of Akodon. 
A southern representative of A. varius. Greyer than any 
of the members of the A. obscurus- -lenguarum group which 
occur in the intermediate area. 
Akodon benefactus, sp. n. 
Rilied to A. lenguarum, but smaller. 
Character of fur and general colour very much as in 
A, lenguarum, the back equally varying from “ fuscous ” to 
dark ‘ buffy brown,” the colouring resulting from a coarse 
and heavily lined mixture of black and dull “buffy. Under 
surface soiled grey, the bases of the hairs slaty, the tips 
greyish white, varying to pale drabby along the middle line. 
Head like back; eye-rings buffy. Hars rather short, of the 
same general dark colour as head. No contrasted white spot 
on chin. Hands and feet brownish white, their hairs 
brownish basally, white at tip. Tail about equalling body 
without head, upperside blackish, lower dull white. 
Skull decidedly smaller than that of A. lenguarum and 
with scarcely any trace of supraorbital ridges such as often 
develop in old age in that animal. Buea foramina to the 
level of the back of the first lamina of m1 
Incisors about as in lenguarum and obscurus » more pro- 
odont than in ordinary Akodons, but less so than in lacteus, 
the angle in the type 84°. 
Dimensions of the type:— 
Head and body 99 mm. ; tail 65 ; hind foot 19 ; ear 14. 
Skull: greatest length 27 ; condylo-incisive length 26:2 ; 
zygomatic breadth 14°3; nasals 9; interorbital breadth 4:3 ; 
palatilar length 12°5; palatal foramina 5°7; upper molar 
series 4°5, 
flab. Bonifacio, South-west Buen Ayres Province; 
alt. 50 m. 
Type. Adult male.  B.M. no. 16. 10. 3.35. Original 
number 2620. Colleeted 13th May, 1916, by Robin Kemp. 
Presented by Oldfield Thomas. 
This species is relatcd to A. obscurus of Uruguay and 
A, lenguarum of Paraguay, but is paler than the former and 
smaller than the latter. 
Mr. Kemp seems to have found this species living in com- 
pany with A. arenico/a at Jenitacio, just as I did its relative 
A. obscurus in the neighbourhood otf Montevideo. 
