Mammals from Peru and Bolivia. 183 
Oxeymycterus tris, sp. n. 
Size rather less than in O. dnca, Thos. General colour 
rufous, heavily lined with black, especially along the middle 
of the back, so that the dorsal area is noticeably darker than 
the sides, which are a clearer fulvous rufous. Black tips of 
dorsal hairs with a distinet greenish iridescence. Head 
browner. Under surface ochraceous rufous, not sharply 
defined laterally from the rufous of the sides; chin whitish. 
Ears, upper surface of hands and feet, and whole of tail 
black, or a few whitish hairs on the terminal part of the tail 
below. 
Skull, as compared to that of O. cnca, with the nasals more 
pointed and less trumpet-shaped anteriorly and more rounded 
posteriorly, Brain-case slightly broader and shorter and 
without any indications of rudimentary postorbital processes. 
Back of palate level with middle of m.*.  Incisors narrower 
and weaker than in O. inca. 
Dimensions of the type (taken in the flesh) :— 
Head and body 160 millim.; tail 102; hind foot, s. u. 30, 
c. u. 333 ear 22. 
Skull: greatest length 37; basilar length 29; breadth of 
nasal opening 3°5; nasals 14°5x4°5; interorbital breadth 
6°5; breadth of brain-case 15; palate length from henselion 
14°5; diastema 9°7; palatal foramina 81x34; length of 
upper molar series 5°7. 
Hab. San Ernesto, near Mapiri, Upper Beni River. Alt. 
10U0 m. 
Type. Male; "B.M. no. .1.' 1.1.76. Orginal number 
1218. Collected 5th September, 1900, by Mr. P.O. Simons. 
Eleven specimens examined, three from San Ernesto and the 
others from Mapivi itself. 
From Dr, Allen’s O. juliace this species differs by having 
its underside coloured exactly as in O. inca. The latter 
again differs by having its rufous darker and more chestnut 
in tone and spread more uniformly over the body, so that the 
back is little darker than the sides; nor is there any irides- 
cence in the dorsal hairs. The cranial differences have already 
been referred to. 
Oxymycterus mimus, sp. Nd. 
A member of the group of small Akodon-like Oxymycteré, 
the nearest ally being O. bogotensis, ‘Vhos. 
General appearance that of the common small Akodons, in 
colour intermediate between A. caliginosus and A, boliviensis. 
