Bornean and Sumatran Mammals. 251 



white lateral line commencing broadly and abruptly just 

 behind the elbow ; tip of tail blackish. Chest and belly dull 

 buffy yellow, on the latter part somewhat suffused with a 

 blackish extension from the dark lateral lines. 



Skull and teeth as described above. 



Dimensions of the type (an adult skin of doubtful sex) : — • 



Head and body 129 millim. ; tail 106 (with hairs 128) ; 

 hind foot (wet) 28 ; ear (wet) 11. 



Skull: basilar length (c.) 21; greatest breadth 18*2; 

 nasals 6 9x5'l anteriorly, 4*3 posteriorly; interorbital 

 breadth 11*8; intertemporal breadth 14*5; breadth of brain- 

 case 16*5; palate length from henselion 11'2; diastema 

 (tojo. 4 ) 6*4; length of upper tooth-series (from p.* only) 4' I ; 

 breadth of each upper incisor 1*6, of each lower incisor 1*5. 

 Lower jaw : condyle to incisor-tip 19*6 ; height from coronoid 

 to angle 7*5 ; back of condyle to notch behind coronoid 6 6. 



Bab. Mount Kina Balu, N. Borneo. Coll. A. Everett. 



The proper treatment of this most extraordinary little 

 squirrel is a problem of the greatest difficulty, and one for 

 whose correct solution further material is sorely needed. 

 Externally it looks simply a small form of Sciurus notatus, not 

 smaller than S. n. orestes to a greater extent than the latter 

 is than 8. n. typicus, so that it might at first sight be thought 

 merely a still more diminutive subspecies of that widely 

 distributed and variable squirrel. On the other hand, its 

 skull and dentition, notably the incisors, are so strikingly 

 different from those of all ordinary squirrels, that it would 

 seem necessary to make a peculiar genus for its reception. 

 It might, in fact, be said that we have in it the curious com- 

 bination of an animal at the same time different generically 

 and almost the same specifically as Sciurus notatus. 



Of course there are two obvious alternatives as to its origin 

 — either it is an offshoot of S. notatus which has retained its 

 colour and specialized its dentition, or it is a wholly different 

 animal which has independently developed the highly charac- 

 teristic coloration of S. notatus. Which of these alternatives 

 is the true one may be solved by further material, for, on the 

 one hand, links may be found connecting it with S. notatus 

 through the subspecies orestes (which has broader incisors 

 than typicus), or, on the other, further species allied to it 

 may turn up without the characteristic coloration of S. notatus. 

 In any case, however, bearing in mind the great importance 

 ot the shape of the skull among the Sciuridai, it seems advis- 

 able to have a generic name for a species with such a peculiar 

 skull and highly modified teeth. 



