448 PROCEEDINGS OF THE NATIONAL MUSEUM. vouxxvi. 



Cranial measurements of type: Greatest length, 62; basal length, 

 52; basilar length. 49; length of nasals, 20; least interorbital breadth, 

 23.'4:; zyo-omatic Ijreaclth, :-'.T; mandible, 36.6; maxillary molar series 

 (alveoli), 12.8; niandil)ular molar series (alveoli), 13.6. 



SjJecimens exa/uined.— Eight, all from Pulo Tuangku. 



Beniarks. — This squirrel is undoubtedly a near ally of tlie Bufufa 

 affinis aureimiiter of Bonhote.". It differs so widely, however, from 

 Geoff rov's original description of Sciurus aureimnter that I have no 

 hesitation in applying to it a new name. 



RATUFA NIGRESCENS, new species. 



T^y^^. —Adult female (skin and skull). Cat. No. 114556, U.S.N.M. i 

 Collected on Pulo Mansalar off Tapanuli Bay. Sumatra, March 11, 

 1902, by Dr. W. L. Abbott. Original number 1641. 



Characters.— One of the largest known members of the (ijjj7ns- 

 hmguranensis group. Color pattern as in Ratufa hungiiranemls and 

 R. femora lis, but upper parts and tail darkened almost to black. Pale 

 flank patch obsolete. 



Color. — Type: The upper parts at first sight appear to be l^lack, but 

 on closer inspection the color is seen to be seal brown, which in certain 

 lights shows faint traces of raw umber. On sides of body and neck 

 and outer surface of legs the raw umber slightly predominates and the 

 hairs show a fine grizzle, due to minute annulations of the lighter color. 

 Under parts and inner surface of legs raw umber, paler in axillary 

 region and at front of thigh. Pale flank patch barely indicated by a 

 sprinkling of cream buff hairs. Cheeks and chin to level of ears a flne 

 grizzle of blackish and whitish; region surrounding base of whiskers 

 slightly paler. Ears blackish externally, concoler with cheeks inter- 

 nally. Feet blackish. Tail uniform seal brown like back above, the 

 basal half of the hairs tinged with dull raw umber. This color appears^ 

 irregularly at the surface when hairs are disarranged, but without 

 forming any noticeable contrast with the seal brown. The under sur- 

 face of tail appears at first sight the same as the upper, but on disarrang- 

 ing the hairs many of them are seen to be rather thi-kly annulated 

 with cream buff bands, of which there are usually about six, for the 

 most part confined to the basal half. In certain lights these annula-i 

 tions produce the faint indication of a light median area, most notice- 

 able on basal third of tail, 



Shull and teeth. — The skull and teeth show no marked peculiarities. 

 In general form the skull is longer and narrower than that of Ratufa 

 hungaranensls. Teeth, as in R. Imnguranensis, therefore relatively 

 smaller than in R. femoralis. 



Measuremerds. — External measurements of type: Total length, 750 

 head and body, 340; tail vertebrje, 41(); hind foot, 78 (70). Average 

 of five adult females from the type locality: Total length, 728 (705-750) 



«Ami. and Mag. Nat. Hist., 7th ser., V, June, 1900, p. 495. 



