496 Mr. O. Tlioinas on small Mammals 



9. Akodon simulator, Tlios. 



(?. 326, 363, 377, 379, 381, 3S2 ; ? . 322, 368, 369. 



These specimens appear to u^'iee absolutely wit'u tli3 type- 

 series o( simul (tor from Tucumaii, aii'l equally to differ from 

 the Cluiml)iclia glaucinus^ to which they are geographically 

 so much nearer. 



10. Akodon alterus, sp. n. 



S. 325, 327, 353, 359. 



Closely allied to A. spegazzinii, but drabby brown instead 

 of buffy olive. 



Size as in the allied species. Gretieral colour above drabby 

 brown (between " buffy brown'" and " Saccardo's umber " of 

 Ridgway). Under surface dull soiled buffy throughout, tiie 

 hairs broadly slaty at base, drabby or dull buffy terminally ; 

 liairs 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 wliitisli below, the two colours generally well contrasted. 



Skull of the same narrow shape and with the same little 

 swollen brain-case as in A. spegazzinii, this narrowness of 

 skull distinguishing the two species from the members of the 

 arenicola group. Zygomatic plate well projected forward, its 

 anterior edge often tending to be slightly concave. Palatal 

 foramina very longj reaching to the level of the second 

 re-entrant angle on the inner side of m\ Bullee 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*6 ; nasals 9*4 ; interorbital breadth 4*6 ; 

 breadth of brain-case 11; palatilar length 10"4 ; palatal 

 foramina 6"3 ; postforaminal palate 2-9 ; upper molar 

 series 4*3. 



Ilab. (of type) as above. Other specimens from Chumbicha. 



Type. Adult male. B.M. no. 19. 2. 7. 44. Original 

 number 359. CoUecttd 6tli September, 1918. 



A. spegazzinii was described on a specimen from Cachi 

 skinned out of spirit, and the coloration therefore could not 



