3G0 Mr. O. Thomas on some 



Under surface pale bufiy white, the hairs slaty blue for three 

 fourths their length, buny white at their tips ; chin-hairs 

 without slaty bases ; line of demarcation on sides not sharply 

 defined. Ears rather large, almost approximating to the 

 species of Phyllotis, their visible parts when folded thinly 

 hairy, brown ; at their anterior bases a tuft of buff- tipped 

 hairs. Hands and feet well-haired, white ; fifth hind toe 

 short, not or scarcely reaching to the base of the fourth. Tail 

 short, about the length of the body without the head, well- 

 haired, but not tufted ; distinctly bicolor, brown above, white 

 on the sides and below. 



Skull, in proportion to its size, strongly built ; muzzle 

 broad ; interorbital region flat, its edges sharply marked and 

 angular, slightly overhanging the orbits posteriorly. Ante- 

 rior palatine foramina long, extending backwards to the level 

 of the middle prominence of 5Li. 



Dimensions of the type (an aged male in skin) : — 



Head and body 94 millim. ; tail 72 ; hind foot (moistened) 

 21 ; ear (shrunk) 16 ; heel to front of last foot-pad 8" 9. 



Skull : lambda (front of interparietal) to nasal tip 23*5, 

 greatest breadth 14'5 ; nasals 10*5 x 3*1 ; interorbital breadth 

 4*5 ; length of outer wall of infraorbital foramen 3*1 ; palate 

 length from henselion 11*6; diastema 6*7 ; anterior palatine 

 foramina 5'7 X 1*8 ; length of upper molar series 4*3. Lower 

 jaw : condyle to incisor-tip 17 ; height of ramus below 

 5TI3-9. 



Bab. Cosquin, Cordova, Argentina. Coll. E. W. White, 

 Sept. 10, 1882. 



Type: B.M. 83.4.16.1. 



Ihis pretty little species, although by its skull apparently 

 an OryzomySj much resembles externally a diminutive 

 Phylhtis both in general coloration, character of fur, and size 

 of ears ; but 1 know no species of that or any other group 

 with which it could be confounded. 



A codon* Jelskii, sp. n. 



Hespcromys (Habrothri.r) scalops, Gay, Thomas, P. Z. S. 1884, p. 455, 

 pi. xliii. fig. 1 (animal), pi. xliv. figs. 1, 15, and 16 (palate and skull) ; 

 nee Gay. 



Since the above determination was published the discovery 

 of several other species with more or less the peculiar colora- 

 tion of this animal, as shown in the plate quoted, has so much 

 reduced the relative importance of this by itself as a specific 

 characteristic, that I feel no longer able to ignore the differ- 



* Meyen, 1833.— Syn. Habrothrix, Waterh. 1837. 



