RICE RATS 293 



Color. — Upperparts bright intense ochraceous fulvous, moderately 

 lined with black hairs ; underparts buffy whitish, the slaty underfur 

 showing through ; tail dusky above, yellowish below. 



Cranial characters. — Skull of medium size and strength ; zygomata 

 moderately spreading; superciliary beads onl}-- slightly developed; 

 rostrum rather long and straight (not decurved) ; nasals rather broadly 

 (but not squarely) truncate posteriorly ; incisive foramina rather short 

 and broadly open posteriorly — differing markedly from the long 

 slender slits of the ?nexicanus group. 



Measurements. — Average of 5 from type locality : total length 

 235 mm. ; tail vertebrae 128; hind foot 28. 3. 



ORYZOMYS ROSTRATUS sp. nov. 



Zy/e from Metlaltoyuca, Puebla, Mexico. No. 931 12 $ old. U. 

 S. National Museum, Biological Survey Coll. Feb. 5, 1898. E. 

 W. Nelson and E. A. Goldman. Original number 12130. 



Characters. — Size medium or rather large; ears large. Similar to 

 melanotis but larger; pelage coarser (but less harsh than in subspecies 

 megado7i from the coast region of Tabasco and Campeche) ; cranial 

 characters distinctive. 



Color. — Upperparts ochraceous fulvous abundantly lined with black 

 hairs ; underparts buffy white, the slaty basal fur showing through ; 

 ears and tail dark brown; underside of tail irregularly yellowish. 



Cranial characters. — Skull large, rather massive, long and flat- 

 tened; rostrum long and somewhat swollen basal ly by projecting 

 anterior lip of antorbital vacuity ; nasals large, broad, and flat, ending 

 about on plane with premaxilloe ; superciliary beads moderate ; 

 zygomata rather narrow anteriorly and posteriorly but bowed out in 

 middle; zygomatic or outer lip of antorbital vacuity strongly pro- 

 duced; incisive foramina medium. Compared with melanotis the 

 skull is larger ; rostrum much longer and more swollen ; nasals less 

 squarely truncate posteriorly; zygomata bowed strongly outward, 

 widest a little behind middle. 



Rettiarks. — Oryzomys melanotis is a West Coast species (type from 

 San Sebastian, Jalisco). Its representatives on the East Coast are 

 slightly larger, with coarser pelage, larger, flatter and more angular 

 skulls, with decidedly larger rostrum. They range on the east from 

 Alta Mira, Tamaulipas, southerly and easterly to Apazote, Campeche, 

 and perhaps to Yucatan. The southern form (subspecies megadon., 

 from Tabasco and Campeche) is redder in color, the pelage is more 

 hispid, and the molar teeth are heavier than in the northern form. 



