278 MERRIAM 



Characters. — Size large ; ears small ; color light fulvous ; belly 

 yellowish fulvous. 



Color. — Upperparts yellowish or buffy fulvous, moderately lined 

 vi^ith black hairs; underparts buffy yellow or buffy fulvous; ears 

 brown, only slightly darkened toward margins; tail brown above, 

 yellowish below. 



Cranial characters. — Skull large and heavy, with marked super- 

 ciliary beads which in old skulls extend posteriorly over sides of brain- 

 case and are strongly tJiciirved before reaching occiput. 



Remarks. — The only species resembling aquatictis externally is 

 albiventer^ which may be distinguished at a glance by its white 

 belly. 



Measurements. — Average of 4 adults from type locality: total 

 length 2S8 mm. ; tail vertebree 149; hind foot 32.5. 



ORYZOMYS PENINSULA Thomas. 



Orysomys peninsula: Thomas, Ann. & Mag. Nat. Hist., 6th Ser., xx, pp. 

 548-549, Dec, 1897. 



Type locality. — Santa Anita, Peninsula of Lower California, 

 Mexico. 



Characters. — Size rather large ; ears rather small ; tail short ; color 

 grayish ; belly whitish ; skull broad and massive. 



Color. — Upperparts grayish brown, becoming pale fulvous on rump ; 

 back only moderately mixed with black hairs; underparts soiled 

 white, the slaty basal fur showing through ; feet whitish ; tail dusky 

 or brownish above, soiled whitish below. 



Cranial characters. — Skull broad and massive with broadly and 

 rather squarely spreading zygomata ; slender tapering nasals ; long 

 premaxillae reaching far behind nasals; slight superciliary beads; 

 large and broadly open palatal slits, and rather large molars. The 

 skull is so unlike any known species that no comparisons are necessary. 

 It is about the size of mexicanus but has a widely different aspect 

 owing to the broadly and squarely spreading zygomata. The frontal 

 region is lower and narrower than in mexicanus., nasals more slender, 

 premaxillae longer, incisive foramina larger ; molars about the same size. 



Measurements. — Topotype( 9 ad): total length 257 mm.; tail 

 vertebra 138; hind foot 33. 



ORYZOMYS NELSONI Merriam. 



Oryzomys nelsoni Merriam, Proc. Biol. Soc. Washington, Vol. xii, p. 15, 

 January 27, 1898. 



Type locality. — Maria Madre, Tres Marias Ids., Mexico. 



