?>GG ^Fr. 0. Thomas on new Species of 



XLVII. — Xew Species 0/ Saccopteiyx, Sciurus, Hliipidomys, 

 andT?ii\xfi-om South America. By Oldfield Thomas. 



Saccopteryx canescens, sp. n. 



Closely allied to S. leptura and 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 ot" the skull and dentition. 



But the ears are narrower, their inner margin above being 

 faintly concave instead of being evenly convex throughout ; 

 tlie tragus is also slightly smaller and narrower. 



The main difference, however, is in colour. S. leptura is 

 dull chestnut-brown all over, with the exception of the two 

 whitisli lines which run down the back. S. canescens^ on the 

 other hand, is light greyish olivaceous, the part between the 

 lines darker than that outside them ; tliis 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 processes are short and blunt, and the teeth are 

 extremely small and delicate. The upper canines are particu- 

 larly slender and weak, and the distance between their tips in 

 the type is only 2*4 millim. instead of 2*7 millim. 



Dimensions of the type : — 



Forearm 39 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*2; 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 

 incisors 5*1. 



A spirit-specimen (J) measures: — Forearm 06 millim.; 

 head and body 38 ; tail 13 ; tail free from membrane 3 ; 

 ear 11 ; tibia 16 ; hind foot, s. u. 5*6, c. u. 6*5; calcar 15. 



Hah. (of type). Obidos, on the Amazon. Other specimens 

 in the Museum from the Orinoco and Surinam. 



Type (apparently female). B.M. no. DD. 11. 2. 2. Collected 

 21st May, 1898, and presented by J. Trumbull, Esq. 



In spite of its close identity in all essential characters with 



