1915.] Allen, Review of the South American Sciuride. — 199 
Genus Leptosciurus gen. nov. 
Plate VII, Figs. 7-14; Plate XIII, Figs. 5-10; Text Figs. 2, 3 (p. 162). 
Type, Sciurus rufoniger Pucheran = Macroxus pucheranw Fitzinger (to 
replace rufoniger, preoccupied). 
Similar (in the typical phase) in external appearance to Microsciurus, 
but size larger and tail relatively longer and fuller (about 46% of total 
length instead of 40%). Mamme, 6. 
Premolars, ¢. Skull similar in general form and ssbiopuettoies to that of 
Guerlinguetus estuans. Differs from Guerlinguetus in the structure of the 
upper molars, the outer border of the crowns having only two prominent 
cusps instead of three, and the intervening cusplets, usually prominent in 
Guerlinguetus and in most other American tree squirrels, are practically 
obsolete or entirely absent. The mamme are also 6 instead of 8, and the 
tail is relatively shorter (about 46% of the total length instead of 50%). 
Geographic distribution.— The Colombian Andes and parts of Peru and 
Bolivia. (See Map, p. 301.) 
Remarks.— Leptosciurus is primarily based on the Sciwrus pucherani 
eroup, which in size, coloration, and texture of pelage greatly resembles 
the larger forms of Microsciurus. With it, on the basis of the tooth struc- 
ture, number of mammee, and relative length of the tail must be associated 
the Sciurus ignitus (=“cuscinus”’) group and Gray’s Macroxus leucogaster, 
which latter differs from all the others in slightly larger size, different 
coloration, and coarser pelage. 
List of Species and Subspecies, with their type localities, and statement of 
number of specimens examined. 
Leptosciurus pucherani pucherani (Fitzinger). Bogota, Colombia. 
Specimens examined, 8. 
Leptosciurus pucheranii medellinensis (Gray). Medellin, Antioquia, 
Colombia. Specimens examined, 3. 
Leptosciurus pucheraniw caucensis (Nelson). Rio Lima, near San An- 
tonio, Western Andes, Colombia. Specimens examined, 8. 
Leptosciurus pucheranii salentensis (Allen). Salento, Central Andes, 
Colombia. Specimens examined, 14. . 
Leptosciurus ignius agree (Gray). Astillero, Bolivia. Specimens ex- 
amined, 13. 
Leptosciurus ignitus trroratus (Gray). Ocabamba, Peru. Specimens 
examined, 13. 
Leptosciurus leucogaster Gray. Santa Cruz de la Sierra, Bolivia. Speci- 
mens examined, 7. 
