234 Mr. O. Thomas on new Members of the 
Skull very similar to that of H. Salvin? (typicus), but 
rather smaller and more delicately built ; interparietal large, 
its length 54 per cent. of its breadth ; upper incisors forming 
a segment of a very small circle, so that their tips are much 
bent inwards towards the mouth, and the diastema is propor- 
tionally short. 
Dimensions of the type (a beautifully prepared ? skin) :— 
Head and body 104 millim., tail 1138, hind foot 24°8, ear 
from notch (contracted) 12. 
Skull: basal length 26°5, greatest length 31:6, greatest 
breadth 15°2; nasals, length 12°7, breadth 3°6 ; interorbital 
breadth 7:7; interparietal, length 4°6, breadth 8:5; diastema 
7°7 ; length of upper molar series 4:3. 
Hab. Mineral San Sebastian, Jalisco, Mexico, 4300 feet. 
Coll. Dr. A. C. Buller, May 9, 1893. 
Heteromys Salvini nigrescens, subsp. n. 
Colour very similar to that of H. S. typicus, but the 
yellowish grizzling on the back, inconspicuous in that animal, 
is entirely absent, at least along the mesial line, so that the 
dorsal colour is a deep uniform smoky brown. Towards the 
sides a few yellow-tipped hairs are present, but not in suffi- 
cient numbers to affect the general tone. No trace of a 
yellowish lateral line. Limbs as in H. S. typicus. 
Skull decidedly smaller and more delicate than in the 
typical form, the muzzle more slender, the interorbital region 
narrower, and the interparietal conspicuously smaller (its 
length-breadth percentage 51). 
Dimensions of the typical skin (B.M. 69. 7. 19. 6) :-— 
Head and body 127; tail broken; hind foot without 
claws 25. 
Skull: greatest length 32°7, greatest breadth 15:4; nasals, 
length 12:7, breadth 3°8; interorbital breadth 6°8; inter- 
parietal, length 4:1, breadth 8; diastema 9°4; length of 
upper molar series 4°7. 
Hab. Costa Rica. 
Neotoma macrotis, sp. n. 
Intermediate in size between the western N. floridana and 
N. mexicana. Colour, so far as can be made out in a spirit- 
specimen, very much as in the latter species. Belly-hairs 
white-tipped. Feet white, faintly clouded proximally with 
