new }[ammals from South America. 269 



faint buffy tinge, the hairs on the throat and chest being 

 entirely of this colour, while those of the belly are slaty just 

 at their bases. In the present form, of which three quite 

 similar adult examples are available, the hairs of the che3t 

 and belly are slaty for their basal halves, while their terminal 

 halves are deep yellowish buffy, little lighter than the yellow 

 of the back and sides. The throat is, however, still white, 

 as in the typical form. Ears, limbs, and tail apparently as 

 in typicus. 



Dimensions of the type (measured in skin) : — 



Head and body 120 millim. ; tail 127 ; hind foot (wet) 26. 



Skull: greatest length 30*3 ; greatest breadth (c.) 16; 

 palatal foramina 5x 2'2 ; length of upper molar series 4 - 8. 



Hub. W. Cundinamarca. Coll. G. D. Child. 



Type B.M. no. 93. 7. 3. 2. 



The number of specimens examined seems to indicate that 

 this animal, slight as its differences are from the true O.jlavi- 

 cans of IVIerida, is yet locally constant, and therefore should 

 have a distinguishing name. It is also evidently different 

 from the brilliantly yellow-bellied form inhabiting the Sierra 

 de Santa Marta, a specimen of which I have seen by the 

 kindness of Mr. Outram Bangs. 



Zyyodontomys brunneus, sp. n. 



Closely allied and very similar in all respects to Z. brevi- 

 cauda, Allen, from Trinidad, but rather larger, with longer, 

 softer fur (hairs of back 12-14 millim. in length), and the 

 general colour markedly different owing to the absence of the 

 rufous tinge so evident, especially posteriorly, in that species. 

 The colour is therefore a very uniform finely grizzled brown, 

 not more rufous posteriorly than anteriorly. Belly dirty 

 greyish, the tips of many of the hairs buffy. Ears short, 

 their hairs black. Upper surface of hands and feet dull 

 white. Tail about as long as the body without the head, 

 finely haired, blackish above, whiter below, though less 

 distinctly bicolor than in Z. brevicauda. 



Skull with the nasals broad and square posteriorly and 

 the palatal foramina markedly broadened mesially, especially 

 in old age. 



Dimensions of the type (an adult female, in skin) : — 



Head and body 152 millim.; tail (c.) 117; hind foot 

 (wet) 25 ; ear (wet) 19. 



Skull (of another specimen) : greatest length 34 ; basilar 

 length 28 ; greatest breadth 17'7 ; interorbital breadth 5 ; 

 palate length to henselion 15 ; diastema 9'5; palatal foramina 

 7*2 x 3; length of upper molar series 5. 



