382 Neiv Bodents from the Orinoco and Ecuador. 



allies ; cheeks, sides of body, and hips clearer rufous. Under 

 surface and inner side of limbs pure sharply defined white 

 throughout. Upper surface of hands and feet white, browner 

 along their outer edges. Tail about the length of the head 

 and body, thinly haired, brown above and white below. 



Skull (of a specimen with all the molars up and worn) 

 almost exactly similar in size to that of a young E. trinitatia 

 with only three molars erupted. Nasals slightly surpassing 

 premaxillje ; supraorbital edges delicately ridged, the ridges 

 disappearing almost immediately after passing the fronto- 

 parietal suture ; pterygoids narrow, not broadened or spatu- 

 late terminally. Molars very small, of the usual structure. 



Dimensions of the type (an adult female, measured by the 

 collector in the flesh) : — 



Head and body 198 millim. ; tail 198; hind foot (s. u.) 40 ; 

 ear 24. 



Skull: greatest length 49"5 ; basilar length 84'8; greatest 

 breadth 23-3; nasals, length 17-5; interorbital breadth 104; 

 palate length from henselion 17 ; diastema 10*5 ; palatal 

 foramina 6x3; length of upper molar series 7"7. 



Hah. Munduapo, Upper Orinoco. 



Type B.M. no. 99. 9. 11. 47. Original number 12126. 

 Collected^ Feb. 27, 1899, by Geo. K. and Stella M. Cherrie. 

 One specimen only. 



Its small size will readily distinguish this Echimys from any 

 of its allies. The type, as shown by its teeth, is fully adult, 

 but is no larger than half-grown specimens of E. trinilatis. 



Loncheres [Isothrix) histriatus orinocij subsp. n. 



Similar in size and general characters to the typical form 

 from the Rio Guapord, but the bright yellow frontal line is 

 dulled to grizzled grey, passing on each side, without sharp 

 contrast, into the dark supraorbital lines. Behind each ear a 

 prominent whitish patch, contrasting with the blackish nuchal 

 part of the coalesced supraorbital lines. Other characters as 

 described in subsp. typicus. 



Dimensions of the type (an adult female, measured in the 

 flesh by collector) : — 



Head and body 232 millim. ; tail 273; hind foot (s. u.) A2. 



Skull : greatest length 67 ; basilar length 43*4 ; greatest 

 breadth 29-5; nasals 165x7; interorbital breadth 13-8; 

 palate length from henselion 19'7 ; palatal foramina 5*1 x 3 ; 

 length of upper molar series 11"5. 



Hah. Maipures, Upper Orinoco. 



Type B.M. no. 99. 9. 11. 45. Original number 11755. 



