ALLEN: mammalia: MURID/F,. 'yo 



Adult (February). — Pelage full, soft and long. Above nearly uniform 

 hair brown with a slight yellowish suffusion ; sides of head and body and 

 under parts whitish gray, the plumbeous underfur nearly concealed by the 

 long white tips of the hairs ; ears small, thickly clothed with short hairs of 

 the color of the dorsal surface ; tail short, well clothed, bicolor, brown 

 above and whitish gray below ; upper surface of fore and hind feet soiled 

 whitish with a faint tinge of flesh-color, palms and soles naked, the former 

 yellowish flesh-color, the latter similar but slightly darker. 



Meas^lrements. — Vo^xx2.A^A\ males measure : Total length, 174 mm • tail 

 vertebrae, 52; hind foot, 25.5. Three adult females measure: Total 

 length, 174 (168-180) ; tail vertebrae, 47 (45-50) ; hind foot, 25.3 (25-26). 

 The longest fore claws have a length of 6 to 7 mm., the longest hind 

 claws measure 4 to 5 mm. 



Skull (adult female) : Total length, 30 ; basal length, 26 ; greatest 

 breadth, 14 ; interorbital breadth, 5; length of nasals, 12 ; palatal length, 

 13; diastema, 8; palatal foramina, 7; upper molars, 5. 



This species is represented by 9 specimens taken on the upper Rio 

 Chico, near the Cordilleras, in February, 1897, by Mr. O. A. Peterson. 

 They are all adult and very uniform in coloration, but vary a little in gen- 

 eral tone, from yellowish brown to reddish brown. 



Its nearest known relative is the A. macronyx Thomas, decribed from 

 the " east side of the Andes, near Fort San Rafael, Province of Mendoza," 

 with which Mr. Thomas thus compares it : "General appearance and pro- 

 portions very much as in A.\C.) macronyx Thos., but colour darker, tail 

 more distinctly bicolor, and skull broader and flatter." He says further: 

 "This species is the southern representative of A. macronyx Thos., to 

 which it is no doubt very nearly allied ; but the fresh series now avail- 

 able indicates that it should have a name of its own." 



Specimens from the Rio Chico, Cordilleras, Patagonia, were sent some 

 years ago by Dr. Merriam to Mr. Thomas for identification, and were 

 labelled by him as ^' Akodon macronyx, Thos." With these specimens 

 before me, I accepted this identification in preparing my account of this 

 species, written two years ago, but added: "The type locality of this 

 species [A. macronyx] is near Mendoza, nearly a thousand miles to the 

 northward, and in all probability the southern form here described will 

 prove separable from true A. macronyx, at least as a subspecies, on com- 

 parison with a good series of Mendoza specimens." Being without ma- 



