294 



MERRIAM 



Specimens of the northern form from Alta Mira have smaller rostrum 

 and nasals and are not typical. 



Measurements. — Type specimen ( $ old) : total length 277 mm. ; 

 tail vertebrse 141 ; hind foot 32.5. Average of 10 from type locality : 

 total length 251 ; tail vertebrae 135 ; hind foot 32. The average of 5 

 topotypes (all young adults) of melanotis\%'. total length 235; tail 

 vertebrae 128; hind foot 28. 2. 



ORYZOMYS ROSTRATUS MEGADON subsp. nov. 



Type. — From Teapa, Tabasco, Mexico. No. 9997S $ old. U. 

 S. National Museum, Biological Survey Coll. March 24, 1900. E. 

 W. Nelson and E. A. Goldman. Original number 14062. 



Characters. — Similar to rostratus\i\i'(. somewhat smaller; pelage 

 more hispid; color decidedly redder; skull smaller with narrower 

 rostrum; molars larger and heavier. Also similar to wc/a«c//5, but 

 hind foot larger; pelage harsher; color redder [averaging warm in- 

 tense fulvous instead of yellowish or golden fulvous] ; darker from 

 more bountiful admixture of black hairs ; rostrum and nasals longer 

 and larger ; nasals less squarely truncate posteriorly ; molars heavier 

 (broader). 



Remarks. — In ranging westward this animal undoubtedly grades 

 into rostratus^ the type locality of which is Metlaltoyuca, Puebla. 



Measurements. — Type specimen ( $ ad.) : total length 272 mm. ; 

 tail vertebra; 140; hind foot 32.5. A topotype female measures: 

 total length 237; tail vertebrae 122; hind foot 31. 



ORYZOMYS YUCATANENSIS sp. nov. . 



Type from Chichenitza, Yucatan, Mexico. No. 108139 $ yg.-ad. 

 U. S. National Museum, Biological Survey Coll. Feb. 9, 1901. E. 

 W. Nelson and E. A. Goldman. Original number 14527. 



Characters. — Very similar to melanotis but fulvous more extended 

 anteriorly, covering sides of face to nose \melanotis has a whitish 

 cheek patch between eye and mouth] ; ears fulvous brown instead of 

 blackish [blackish in young] ; underparts white ; underside of tail 

 yellowish throughout; head and back moderately lined with black 

 hairs. 



Cranial characters. — Skull rather small, with distinct superciliary 

 beads, short incisive foramina, and very small molars. Contrasted 

 with melanotis the skull is smaller (?), superciliary bead more 

 prominent ; nasals less squarely truncate posteriorly ; incisive fora- 

 mina shorter; molars smaller. 



