new Forms of Akodon and Pliyllolis. 405 



Ecuador by Mr. Perry Simons shows that the form inhabiting 

 the Andes is, as might be expected, readily distinguishable 

 by its longer fur and deeper colour from tiuit which inhabits 

 the low and more or less desert coast strip at the north- 

 western corner of Peru. The type of A. vwUis came from 

 Tumbez, at the noithi-rn end of this coast strip, and tiiere is 

 a good series in the Museum from Eten and other localities 

 further southwards which agree fairly closely with it and are 

 evidently referable to the same form. All Mr. Simons's other 

 specimens, from the highlands, are of the darker character 

 now described. 



Akodon arviculoides montensis, subsp. n. 



Like the ordinary large Akodon of East and Southern 

 Biazil, but markedly paler and more buffy. 



Size averaging slightly smaller than in true arviculoides. 

 General colour al)ove grizzled olive-grey, paler and more 

 bufFy than in arviculoides. Rump and sides prominently 

 buffy or clay-colour. Under surface pale bufFy, the bases of 

 the hairs slaty. Hands and feet dull whitish, not so brown 

 as in arviculoides. 



Skull rather lighter in build than in true arviculoides, the 

 brain-case slightly narrower. Supraorbital edges generally 

 with a slight postorbital angle, which does not appear to 

 occur in arviculoides. 



Dimensions of the type (measured in flesh) : — 



Head and body 128 mm. ; tail 97 ; hind foot 24 ; ear 19. 



Skull: greatest length 31; condylo-incisive length 27*7; 

 zygomatic breadth 15 ; nasals 12*5 ; interorbital breadth 5 ; 

 breadth of brain-case 12*4 ; palatal foramina 7 ; upper molar 

 series 4*1. 



Ilab. Paraguay. Type from Sapucay. 



Ti/pe. Adult male. B.M. no. 4. 1. 5. 35. Original 

 number 1022. Collected 31st July, 1903, by W. Foster. 

 Fifteen specimens examined. 



" Trapped in monte." — W. F. 



This is evidently the Paraguayan representative of the 

 common large Akodon of Brazil, for which, in its typical 

 form, from Bahia, I believe tiie name arviculoides *, Wagn., 

 should be used, orohinus, Wagn., being a synonym of it ; 



* I regret to be able to find no excuse for using the correct fonn of 

 this word, arvicoloides. Pictet wrote arvicoloides, but Wagner used the 

 incorrect form arviculoides four times over, in different publications, so 

 that it cannot be treated as a misprint. 



