348 Mr. O. Thomas on some 



shows the grooving of the incisors, different as the details of 

 this are ; but the typical and still unique specimen has its 

 molars too worn to say whether they at all approach those of 

 Neotomys. 



Neotomys ehriosus, sp. n. 



Size and general proportions about as in Rhithrodon pictus, 

 although the feet and tail are rather shorter. Fur long and 

 straight, the underfur of the back about 13 and the bristle- 

 hairs about 19 millim. long. Ears large, nearly circular in 

 outline, laid forwards they reach just to the back of the eye ; 

 well clothed with brownish-fulvous hairs on both surfaces. 



General colour, so far as can be made out in a spirit- 

 specimen, grizzled greyish brown (not unlike Sigmodon 

 hispidus), the tip and sides of the muzzle bright cinnamon- 

 rufous, a colour which is also present on a few hairs at the 

 base of the ears and on the rump. Belly-hairs plumbeous 

 basally, white terminally. Upper surfaces of feet dirty 

 whitish, with a tinge of cinnamon. Palms and soles quite 

 naked, pads 5-6 ; fifth hind toe reaching nearly to the end of 

 the first phalanx of the fourth. Claws small and delicate, 

 the anterior smaller than the posterior. Tail rather shorter 

 than the body, bicolor, the upper surface blackish, the sides 

 and lower surface white. Palate with the usual three undi- 

 vided ridges, then follow two divided ones at the front end of 

 ^ ; but behind these there are no regular ridges, the surface 

 of the palate being smooth, with several irregular and unsym- 

 metrical projections upon it. 



Dimensions of the type (an adult male in spirit) : — 



Head and body 100 millim. ; tail 61 ; hind foot 21*5 ; ear, 

 from notch, ]5"8 by 13*2 broad ; forearm and hand 27 ; heel 

 to front of last foot-pad 10. 



Skull : basal length 23'6, basilar length from henselion 

 21*3, greatest breadth 15"7; nasals, length 12*8, greatest 

 breadth 5*0 ; breadth between anteorbital fossaj 4 ; inter- 

 orbital breadth 3*4; interparietal, length 3*1, breadth 9'4; 

 length of outer wall of infraorbital foramen 2 '4 ; palate, length 

 from henselion 11*9; palatal foramina 5*5 ; diastema 6*5; 

 length of upper molar series 5"2. Lower jaw: condyle to 

 incisor-tip 17 ; tip of coronoid to angle 9*8 ; length of lower 

 molar series 5"6. 



Eab. Valley of Vitoc, East Central Peru. Coll. J. Kali- 

 nowski. 



Type: B.M. 94.10.1.1. 



This interesting little animal adds another to the number of 

 South-American small mammals presenting to a greater or 



