1893-] Allen and Chapman on Trinidad Mammals. 213 



longer than head and body, the basal half inch heavily furred and colored, below 

 as well as above, like the rump, forming a basal, furred, yellowish brown ring ; 

 rest of the tail uniform pale brown, annulations very narrow and indistinct, 

 the scales minute, practically naked except near and at the tip, where it is 

 thinly clothed with short dusky hairs, forming a minute, scarcely appreciable 

 pencil. Under a lens the whole tail is found to be haired, but so scantily as 

 not to appreciably obscure the annulations. Whiskers scanty, black. 



Measurements, from the fresh specimen : Total length, 261 mm. ; head and 

 body, 124 ; tail vertebrae, 137 ; hind foot, 24 ; ear from crown, 14. 



Skull, in general features, much like that of O. palustris ; it is, however, 

 heavier and larger, with a heavier raised supraorbital ridge ; the interparietal is 

 also several times larger, relatively as well as absolutely ; the anterior palatine 

 foramen is shorter and much broader. Total length, 30.5 ; basal length, 25 ; 

 greatest zygomatic breadth, 17.3 ; greatest mastoid breadth, 12.2 ; least 

 interorbital breadth, 5.6 ; length of nasals, n ; length (antero-posterior axis) 

 of interparietal, 5 ; breadth (transverse axis) of interparietal, 9.4 ; length of 

 anterior palatine foramen, 5.6 ; greatest breadth of same, 2.8 ; distance between 

 incisors and first molar, 7 ; length of crown surface of upper molar series, 4. 5 ; 

 length of lower jaw (point of incisor teeth to posterior border of condyle), 18.8 ; 

 height at condyle, 8 ; length of crown surface of lower molar series, 4.8. 



Type and only specimen, No. ffyf, ? ad., Princestown, Trinidad, April 26, 

 1893, coll. Frank M. Chapman. 



This species in size, proportions and coloration, strongly sug- 

 gests Hesperomys concolor Wagner, from the Rio Curicuriari, in 

 northeastern Brazil, with which it may prove to be identical. 



14. Oryzomys trinitatis, sp. nov. 



Pelage full, soft and rather long (13 mm. on the middle of the back). Color 

 above bright yellowish rufous, darker, approaching chestnut, and finely varied 

 with black-tipped hairs over the middle of the dorsal region, lighter and more 

 strongly yellowish on the sides ; nose blackish and head rather darker than 

 back ; below grayish white, the tips of the hairs being soiled whitish and the 

 basal portion gray, showing more or less through the surface. Line of demar- 

 cation between the coloration of the dorsal and ventral surface not sharply 

 defined. Ears rather large and quite broad, dusky, and thinly coated with very 

 short blackish hairs. External surface of fore and hind limbs dusky yellowish 

 brown, becoming lighter grayish brown on the toes, which are thinly haired ; 

 palms and soles naked, the former brownish flesh color, the latter more dusky 

 and 6-tuberculate. Hind feet rather broad in proportion to their length. Tail 

 very much longer than head and body, furred all around for the basal half inch, 

 the fur yellowish ashy below and colored like the rump above ; remainder of the 

 tail pale dusky brown, unicolor, non-penicillate and practically naked throughout, 



