new Neotropical Muridae. 355 



Dimensions of the type (a skin) : — 



Head and body 121 millim. ; tail 139 * ; hind foot 30 ; ear 

 from notch 18*5. 



Skull : front of interparietal to nasal tip 28*3, greatest 

 breadth 16 ; nasals 12" 7 x 4 ; interorbital breadth 5"1 ; length 

 of outer wall of infraorbital foramen 3*4 ; palate length from 

 henselion 13'4 ; diastema 8; palatal foramina 5*5 x 2*5; 

 length of upper molar series 5. Lower jaw : condyle to 

 incisor-tip 20 ; height of ramus below sn. 4*4. 



Hab. Tumbez, N. Peru. Coll. Dr. J. Stolzmann. 



Type: B.M. 85.4.1.47. 



This species is undoubtedly very nearly allied to 0. gala- 

 pagoensis, but may be distinguished by its yellowish instead 

 of brownish colour, its shorter fur, and longer tail. One 

 would also expect, almost as a matter of course, that the 

 insular form of the Galapagos Islands would be specifically 

 distinguishable from that of the mainland. 



Oryzomys phceopus, sp. n. 



General appearance somewhat of the 0. laticeps type, but 

 size smaller and tail shorter. Fur straight and rather harsh, 

 about 11 millim. in length on the back. Colour above 

 coarsely grizzled fulvous and black, the general tone near 

 Ridgway's " vandyke-brown," scarcely paler or clearer on 

 sides. Whole of under surface dirty buff, the hairs pale 

 plumbeous basally, dull buff terminally ; line of demarcation 

 not sharply defined. It may be noted that the colour above 

 exactly matches the cheeks, and below, the belly, of a July 

 example of the English water-vole. Ears short, thinly 

 haired, scarcely darker than the general colour of the head. 

 Upper surfaces of metacarpals and metatarsals well clothed 

 with dark brown hairs ; digits more thinly clothed and rather 

 paler. Tail comparatively short, very finely haired, in fact 

 almost naked ; brown above, paler below, but the difference 

 not conspicuous. 



Skull somewhat like that of 0. laticeps, but smaller and 

 with a shorter muzzle. Interorbital region convex, broad, its 

 edges with a fine supraorbital bead. Palatine foramina just 

 about the length of the upper molar series. Coronoid pro- 

 cesses of lower jaw long, well hooked backwards. 



Dimensions of the type (a male in skin) : — 



Head and body 112 millim. ; tail 98 ; hind foot (moistened) 

 24; ear (shrunk) 14; heel to front of last foot-pad 11*5. 



* Imperfect at tip; the tail of another specimen is of about the same 

 length as that here given. 



