Vol. XXVIII, pp. 127-130 June 29, 1915 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



FIVE NEW RICE RATS OF THE GENUS ORYZOMYS 

 FROM MIDDLE AMERICA. 



BY E. A. GOLDMAN. 



The following descriptions of new species and subspecies of 

 Oryzomys are published in the course of a revision of the North 

 and Middle American forms of the genus now in progress. 

 These represent widely differing groups, three forms being from 

 Mexico, one from Panama, and one from Costa Rica included 

 with other material from that country kindly loaned by 

 Dr. J. A. Allen, Curator of Mammalogy, American Museum 

 of Natural History. 



Oryzomys guerrerensis sp. nov. 



Type from Omilteme, Guerrero, Mexico. No. 127,517, male adult 

 (molars moderately worn), U. S. National Museum (Biological Survey 

 Collection), collected by E. W. Nelson and E. A. Goldman, May 20, 

 1903. Original number 16,454. 



General characters. — A small species similar in general to 0. melanotis, 

 but decidedly smaller; color darker; ears wholly black [inner sides 

 clothed with rusty reddish hairs in melanotis] ; skull with very low, flat 

 braincase. 



Color. — Type (fresh pelage): Upperparts ochraceous-tawny (Ridgway, 

 1912), purest on cheeks, shoulders and sides, the face, top of head, and 

 back darkened by a moderate admixture of black hairs ; underparts dull 

 grayish white, the plumbeous basal color of the fur showing through; 

 outer and inner sides of ears well clothed with deep, glossy black hairs; 

 feet whitish, the claws of longer toes overlapped by tufts of silvery bristles; 

 tail brownish above, irregularly flesh color below to near tip, which is 

 dusky all around. 



Skull. — Similar in general to that of 0. melanotis, but much smaller 

 and lighter, with more slender zygomata; braincase similarly broad, but 

 very much lower and flatter; outer wall of antorbital foramen with 

 anterior border more rounded and less noticeably projecting forward as 

 viewed from above; interparietal smaller; anterior palatine foramina 

 about as broad anteriorly as posteriorly [broader posteriorly in melanotis] ; 

 teeth as in melanotis, but smaller. 



24— Proc. Biol. Soc. Wash,. You XXVIII, 1915. (127) 



