130 Proceedings of the Biological Society of Washington. 



parts, including lips, dull whitish ; outer sides of ears blackish, the 

 inner sides clothed with buffy hairs; feet white; tail light brownish 

 above, whitish or flesh color below on basal half, becoming brownish all 

 around toward tip. In other examples the underparts vary from nearly 

 pure white to light buff. 



Skull. — In general form very similar to that of 0. c. couesi, but much 

 larger, with heavier dentition ; anterior palatine foramina about equal to 

 palatal bridge [usually longer than palatal bridge in 0. c. couesi], and 

 ending posteriorly near anterior plane of first molars ; interparietal rela- 

 tively smaller. 



Measurements. — Type: Total length, 305; tail vertebrte 169; hind foot, 

 36. Skull (type): Greatest length, 33.4; zygomatic breadth, 18.3; in- 

 terorbital breadth, 5.2; length of nasals, 12.5; length of anterior palatine 

 foramina, 6.4; length of palatal bridge, 6.4; length of upper molar series, 

 4.9. 



Remarks. — This handsome rice rat is a member of the widely dispersed 

 0. couesi group. It is closely allied to 0. albiventer, a near geographic 

 neighbor, and examination of specimens from intermediate localities in- 

 dicates gradation through intervening forms to typical 0. c. couesi. 



Specimens examined. — Ten, all from the type locality. 



Oryzomys fulvescens lenis subsp. nov. 



Type from Los Reyes, Michoacan, Mexico. No. 125,941, male adult, 

 U. S. National Museum (Biological Survey Collection), collected by 

 E. W. Nelson and E. A. Goldman, February 14, 1903. Original number 

 15,948. 



General characters. — Similar to Oryzomys fulvescens fulvescens but upper 

 parts paler ochraceous-bufF, the general tone more yellowish; skull 

 broader and more massive. 



Color. — Type (fresh pelage): Upper parts in general pale ochraceous- 

 buff, becoming warm buff on cheeks, shoulders and lower part of sides ; 

 the face, top of head and back moderately lined with dark hairs; under 

 parts light buff, except chin and lips, which are white; outer sides of ears 

 blackish, inner sides clothed with ochraceous buffy hairs; feet white; 

 tail light brownish above, flesh color below proximally, becoming dusky 

 all around toward tip. 



Skull. — Broader than that of 0. f. fulvescens ; zygomata more widely 

 spreading; maxillary arms of zygoma and ascending branches of pre- 

 maxillse broader and heavier; dentition rather heavy, but equalled in 

 some examples of 0. f. fulvescens. 



Measurements. — Type: Total length, 198; tail vertebrae, 115; hind foot, 

 23. Skull (type): Greatest length, 22.6; zygomatic breadth, 12.3; inter- 

 orbital breadth, 3.4; length of nasals, 8.6; length of anterior palatine 

 foramina, 3.9 ; length of palatal bridge, 4. ] ; length of upper molar series, 3. 



Remarks. — Oryzomys f. lenis is a pale form of 0. fulvescens ranging at 

 the lower elevations along the Pacific side of Mexico. Aside from paler 

 coloration, it is distinguished from 0. f. fulvescens by the broader, more 

 massive skull. 



