MAMMALS OF THE NATUNA ISLANDS 1 29 



Specimens examined. — Ten (one in alcohol), all from the type 

 locality. 



Remarks. — Though suggesting two of the small South Natuna 

 squirrels in color, Sciurus lautensis is obviously related to the dark 

 colored Bunguran form, with which it more nearly agrees in size. 



SCIURUS NAVIGATOR (Bonhote). 



1894. Sciurus prevostii Thomas and Hartert, Novitates Zoologicse, I, p. 656. 



September, 1894 (Sirhassen). 

 1901. Sciurus prevostii 7iavigator BotinoiK, Ann. and Mag. Nat. Hist., 7th 



ser., VII, p. 171. February, 1901 (Sirhassen). 



Nine specimens, three from Sirhassen Island and six from Pulo 

 Subi. 



Those from Pulo Subi, while agreeing with the topotypes in color, 

 appear to average a trifle smaller, though the series is hardly exten- 

 sive enough to prove that this is constant. 



RATUFA SIRHASSENENSIS (Bonhote). 



1894. Sciurus bicolor albiceps Thomas and Hartert, Novitates Zoologicae, 



I, p. 659. September, 1894 (Sirhassen). 

 1900. Ratufa ephippium sirhassenensis Bonhote, Ann. and Mag. Nat. 



Hist., 7th ser., v, p. 498. June, 1900 (Sirhassen). 



Two specimens, Sirhassen, June 8, 1900. 



This species, though related to Ratufa ephippium.^ with which it 

 agrees in color-scheme, is sharply differentiated by its small size and 

 cranial peculiarities. It is in no way closely allied to Ratufa 

 bunguranensis and R. nanogigas. 



As compared with that of Ratufa ephippium sandakanensis Bon- 

 hote, the skull in addition to its small size (greatest length 57 instead 

 of 65) differs in general narrowness, in the relatively greater breadth 

 of the nasal branches of the premaxillaries, and in the form of the 

 audital bullae. When the skull is held upside down and viewed from 

 behind the bullae are seen to be narrower than in the Bornean animal 

 and to rise to a much greater height above the surface of the basi- 

 occipital. 



RATUFA BUNGURANENSIS (Thomas and Hartert) . 



1894. Sciurus bicolor bu7tguranensis Thomas and Hartert, Novitates Zoo- 

 logicse, I, p. 658. September, 1894 (Bunguran). 



1895. Sciurus bicolor bunguratiensis Thomas and Hartert, Novitates Zoo- 

 logicae, II, p. 491. December, 1895 (Bunguran). 



1900. Ratufa ephippium bungt(ra7iensis Bonhote, Ann. and Mag. Nat. Hist., 

 7th ser., V, p. 497. June, 1900. 



Thirteen specimens from Bunguran, all in various stages of the 



Proc. Wash. Acad. Sci. April, 1901. (129) 



