1 92 Bulletin American Museum of Natural History. [Vol. XIX, 



brown, internally yellowish buff, the hairs at the anterior base of the 

 ears whitish and the post- auricular patch pale buff; upper surface of 

 the feet white; soles of hind feet to base of toes densely haired, dark 

 brown, toes flesh-color; tail with a narrow brown stripe above, sides 

 and below dull whitish. 



Measurements. Type: Total length, 230; tail vertebrae, 78; hind 

 foot, 34. Seven specimens (4 males and 3 females) measure: Total 

 length, 215 (200-230); tail vertebras, 77 (75-82); hind foot, 33.3 (32- 

 35). Skull (type). Total length, 35.7; basal length, 3 1 ; zygomatic 

 breadth, 20.5; interorbital breadth, 4; length of nasals, 16; palatal 

 length, 17.5; palatal foramina, 9; diastema, 8.5; upper molar series, 

 6-4- 



Represented by 10 specimens, all collected by Mr. Peterson 

 in the Cordilleras at the head of the Rio Chico de Santa Cruz, 

 and all but one (the type, taken March n) between February 

 4 and 21, 1897. Part of the specimens, including the type, 

 are in the dress of the breeding season, while others have 

 partly or wholly acquired the post-breeding dress. These 

 have a stronger suffusion of yellowish buff on the sides and 

 ventral surface, but are otherwise similar to the type. A 

 quarter grown young example is similar in general coloration 

 to the adults, except that the ears have the external surface 

 blackish and the internal surface deep buff, with the hairs at 

 the anterior base of the ears and the post-auricular patch also 

 deep buff, in prominent contrast with the surrounding pelage, 

 as is not the case in the adults. 



Reithrodon hatcheri is readily distinguishable from R. cnni- 

 culoides by its much darker and less fulvous coloration, the 

 contrast in color between the two series being conspicuously 

 noticeable. There are apparently no cranial differences of 

 importance. 



Euneomys petersoni, sp. nov. 



Type, No. 84198, U. S. Nat. Mus., $ ad., upper Rio Chico de Santa 

 Cruz, near the Cordilleras, -Patagonia, Feb. 10, 1897; O. A. Peterson, 

 for whom the species is named, in recognition of his important field 

 work on the mammals of Patagonia. 



Similar in coloration to Phyllotis xanthopygus, but very much 

 smaller, with a relatively very short tail and naked soles, but the 

 upper incisors are as strongly grooved as in Reithrodon cuniculoides. 



Adult (type) , February. Pelage very long and soft, almost woolly. 

 Above dark gray-brown, varied with blackish and fulvous, the pelage 



