RICE RATS 283 



Meastiretncnts. — Type specimen ( Z ad.) : total length 290 mm. ; 

 tail vertebrae 154; hind foot 35. 



Remarks. — A specimen from Tehuantepec (No. 734^7 ^ ) ^gi'ees 

 externally with an old specimen from Piaxtla, Puebla, and in cranial 

 characters agrees in the main with aztecus^ having the same downward 

 bowed zygomata and so on, but differs in having the palatal slits more 

 broadly open posteriorly. 



ORYZOMYS MEXICANUS Allen. 



Oryzoinys mexicatius Allen, Bull. Am, Mus. Nat. Hist., ix, pp. 52-53, 

 March 15, 1897. 



Type from Hacienda San Marcos, Tonila, Jalisco, Mexico. 



Characters. — Size medium; hind feet large; ears rather small 

 (smaller than \x\ jalap en) \ color grizzled fulvous brown; underparts 

 white or buffy ; skull massive. 



Color. — Upperparts ochraceous or pale fulvous, deepest on rump, 

 strongly lined with black hairs: underparts white, the belly some- 

 times suffused with buffy ; ears not conspicuously darker than sur- 

 rounding parts ; tail dark brown or dusky, paler below. 



Cranial characters. — Skull broad and massive, with strong zygo- 

 mata, well defined superciliary ridges, long palatine slits, and rather 

 heavy molars. Compared with jalapce the skull is broader and more 

 massive, the zygomata much heavier, especially anteriorly ; supercil- 

 iary beads more pronounced ; molars heavier. 



Measurements. — Average of 2 specimens from Armeria, Colima : 

 total length 275 mm.; tail vertebrae 139; hind foot 33. 



Remarks. — Oryzotnys mexicanus has a wide range in western 

 Mexico. The Biological Survey Collection contains specimens col- 

 lected by Nelson and Goldman from Rosario ni southern Sinaloa, 

 across the states of Tepic, Jalisco, Colima, Guerrero, and Oaxaca, to 

 the isthmus of Tehuantepec. 



ORYZOMYS MEXICANUS PERAGRUS subsp. nov. 



Type from Rio Verde, San Luis Potosi, Mexico. No. 821 11 $ 

 yg.-ad. U. S. National Museum, Biological Survey Coll. January 8, 

 1897. E. W. Nelson and E. A. Goldman. Original number 10398. 



Characters. — Similar to mexicaiius but tail decidedly longer and 

 rather sharply bicolor ; color very much grayer (less fulvous) ; back 

 more copiously and evenly mixed with black hairs ; underparts deeper 

 buffy-fulvous ; ears darker; ascending arms of premaxillae a little 

 heavier posteriorly ; bulla larger ; incisive foramina larger ; molars 

 largfer and heavier. 



