366 Mr. O. Thomas on new Species of 
XLVII.—New Species of Saccopteryx, Sciurus, Rhipidomys, 
and Tatu from South America. By OLDFIELD ‘THOMAS. 
Saccopteryx canescens, sp. 0. 
Closely allied to S. leptura aud agreeing with it in all 
important respects, in size (or, perhaps, rather smaller), 
position of wing-sac, insertion of wing-membrane on the 
ankle, and the main characters of the skull and dentition. 
But the ears are narrower, their inner margin above being 
faintly concave instead of being evenly convex throughout ; 
the tragus is also slightly smaller and narrower. 
The main difference, however, is in colour. SS. leptura is 
dull chestnut-brown all over, with the exception of the two 
whitish lines which run down the back. 8. canescens, on the 
other hand, is ight greyish olivaceous, the part between the 
lines darker than that outside them ; this colour results from 
the hairs being pale brown, finely tipped with buffy; the 
lines themselves are prominent and begin rather further up 
the body, almost on the neck. The head is greyish, with 
two fairly distinct whitish lines running along over “each eye. 
Under surface soiled buffy, the hairs being plumbeous basally 
and buffy terminally. Interfemoral, as in S. leptura, hairy 
to the exsertion of the tail. 
The skull is rather smaller and more delicately built, the 
postorbital Day are short and blunt, and the teeth are 
extremely small and delicate. ‘he upper canines are particu- 
larly slender and weak, and the distance between ee tips in 
the type is only 2°4 millim. instead of 2°7 millim. 
Dimensions of the type :— 
Forearm 389 millim. 
Skull: extreme length 13:2; basal length 10°8; zygo- 
matic breadth 8*2; interorbital breadth 3:1; breadth between 
tips of postorbital processes 4°25 intertemporal breadth 2:1 ; 
breadth of brain-case on squamosals 6°5; combined length 
of upper molars 2°8; length of lower tooth-row exclusive of 
a oul. 
A spirit-specimen (2) measures:—Forearm 36 millim. ; 
head and body 88; tail 13; tail free from membrane 3; 
ear 11; tibia 16; hind foot, s, u. 5°6, c. u. 6°5; calcar 15. 
Hab. (of type). Obidos, on the Amazon. Other specimens 
in the Museum from the Orinoco and Surinam. 
Type (apparently female), B.M.no. 99.11. 2.2. Collected 
21st May, 1898, and presented by J. Trumbull, Esq. 
In spite of its close identity in all essential characters with 
