MAMMALS OF THE NATUNA ISLANDS 1 27 



Specimens examined. — Seven, all from the type locality. 



Rei7iarks. — This squirrel is remarkable among the Natuna members 

 of the S. notatus group for the brilliant color of its vmder parts. In 

 this respect it surpasses all of the related forms with which I am ac- 

 quainted. The red color is, however, strictly confined to the body, 

 showing no tendency to spread to the tail as in S. miniatiis of the Ma- 

 lay Peninsula. 



SCIURUS RUBIDIVENTRIS sp. nov. 



1894. Sciurus noiatus Thomas and Hartert, Novitates Zoologicas, i, p. 659. 

 September, 1894 (part, specimens from Bunguran). 



1895. Sciurus tiotatitsTnouxs and Hartert, Novitates Zoologlcae, 11, p. 491. 

 December, 1895 (part, specimens from Bunguran). 



Type. — Adult female (skin and skull) No. 10467 1 U. S. National 

 Museum. Collected on Bunguran Island, North Natunas, June 22, 

 1900. Original number 49S. 



Characters. — Size and general appearance both above and belo\v as 

 in the Bornean form of Sciurus notatus., but red of under parts brighter, 

 and cheeks and chin distinctly less fulvous than surrounding parts. 

 Skull with broader, deeper braincase than in the Bornean animal. 



Color. — The color so closely resembles that of the Bornean Scizcrus 

 notatus that no detailed description is necessary. Under parts ochra- 

 ceous-rufous, fading to tawny on throat, everywhere lighter and more 

 tinged with red than in the Bornean animal. In the latter the color 

 of the under parts extends forward to lips and also strongly suffuses the 

 cheeks and sides of head which are only a shade browner than the 

 throat and conspicuously more fulvous than top of head and sides of 

 neck. In Sciurus rubidiventris the cheeks and lips are noticeably 

 suffused with gray so that they form a distinct contrast with both throat, 

 top of head and sides of neck. 



Skull. — The skull agrees in general size with that of the Bornean 

 animal, and is therefore much larger than in thethi"ee species from the 

 South Natunas. It is distinguishable by greater general breadth and 

 by the depth of the braincase, which perceptibly exceeds that of S. 

 fiotatus. 



Measure?ne7tts. — External measurements of type : total length 380 ; 

 head and body 209 ; tail vertebrae 171 ; hind foot 49 (44.5). Averages 

 and extremes of seven specimens from the type locality : total length 

 37S (3^S~393) ' head and body 208 (203-223) ; tail vertebrae 173 

 (165-184) ; hind foot 49.3 (48-50) , hind foot without claws 45.7 



(44-5-47) • 



Cranial measurements of type: greatest length 52.4 (50.4);^ basal 

 1 Measurements in parentheses are those of an adult Bornean Sciurus notatus. 



