214 On neio Araentine Speciea 0/ Akodon. 



A soutliern representative of A. varhis!. Greyer than any 

 of the members of the A. ohscurus-leng uanim group wliich 

 occur in tlie intermediate area. 



Akodon bene/actus, sp. n. 



Allied to A. lenguanim^ but smaller. 

 . Character ot fur and general colour very much as in 

 A. lenguarum, the back equally varying from " fuscous^' to 

 (lark *' bufF\ -brown/' the colouring resulting from a coarse 

 and heavily lined mixture of black and dull huffy. Under 

 surface soiled grey, the Wses of the hairs slaty, the tips 

 greyish white, varying to pale drabby along the middle line. 

 Head like back; eye-rings buflfy. Ears 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 

 Avithout head, upperside blackish, lower dull white. 



Skull decidedly smaller than tliat of A. lenguarum and 

 M ith scarcely any trace of supraorbital ridges such as often 

 develop in old age in that animal. Palatal foramina to the 

 level of the back of the first lamina of m^. 

 , Incisors about as in lenguaium and obscurus, more pro- 

 odont than in ordinary Akodons, but less so than in lacteus^ 

 the angle in the type 84°. 



Dimeiisions of the type : — 



Head and body 99 mm. ; tail C5 ; hind foot 19 ; ear 14. 



Skull: greatest length 27 ; condylo-incisive length 26*2 ; 

 zygomatic breadth 14*3 ; nasals 9; interorlital breadth 4*3 ; 

 palatilar length 12'5 ; palatal foramina 5*7 ; upper molar 

 series 4*5. 



Hob. Bonifacio, South-west Buenos Ayres Province; 

 alt. 50 ni. 



Type. Adult male. B.M. no. 16. 10. 3. 35. Original 

 laimber 2(120. Collected 13th May, 1916, by Kobin Kemp. 

 Presented by Oldfield Thomas. 



This species is related to A. obscurus of Uruguay and 

 A. lenguarum of Paraguay, but is paler tiian the former and. 

 sinaller than the latter. 



J\lr. Kemp seems to have found this species living in com- 

 pany with A. are7iico/a at Bonifacio, just as I did its relative 

 A. obscM'us in the neighbourhood of Montevideo. 



