EODENTIA. 



SCIURID^. 



Genus Sciurus, Linn. 



In identifying the squirrels collected on the two Expeditions to Western China, 

 I was led to examine the whole group of the south-eastern Asiatic species of the 

 genus Sciurus, and the results are here recorded. 



That remarkahle Malayan and Bornean form, with the long snout, which has 

 been elevated by Dr. Gray to a separate genus under the term Bhinoscmrus, I have 

 made the subject of a few observations at the end of this Memoir. It seems to me 

 that its structural features are not so much differentiated from the ordinary squir- 

 rels as to warrant its being apportioned more than sub- generic rank, and if the other 

 squirrel, also from Borneo, which Dr. Gray first described as Sciurus macrotis and 

 afterwards raised to generic rank as Bheithrosciurus, does not present any other 

 modifications on the ordinary Sciurine type beyond the longitudinal grooving of the 

 incisors, its claims to more than sub-generic distinctness would seem to be doubtful. 



With regard to the genus Scmrus itself, it forms a natural and well-defined 

 group, containing a large assemblage of forms which differ in details of merely 

 specific value. With the two exceptions just mentioned, I fail to detect any 

 characters to favour the view, that variation in dentition, or in the tufting of their 

 ears, occurs to .a degree sufficient to entitle them to be separated into sub-genera. 

 The dentition and tlie form of the skull throughout the group rather present a 

 remarkable uniformity. The tufting of the ears is apparently not a seasonal or 

 climatic circumstance, such as that to which the common squirrel of Europe is 

 well known to be subject. Certain modifications in the external appearance of the 

 animals are doubtless produced by the stage of their growth ; the pelage of some, 

 in whole or in part, becoming darker or lighter, as they pass from youth to matm%! 

 and occasionally there is a complete change of colour. The young of S. rafflesii, 

 for example, I have frequently observed to be born with a pure white tail which 

 gradually changes to black in the adult, showing a slight tendency to rufous tipping; 

 apparently also S . ferrugineus has annulated hair in youth which becomes brilliant 

 red at maturity. But the diversity in the physical conditions of the countries which 

 the squirrels inhabit, and the nature and relative abundance of their food, exercise a 

 most potent influence on their organisms, leading to variations in size, form, and 

 intensity of colour. The species S. maclellandi affords a good illustration of this. It 

 ranges over a wide geographical area, and when a series of individuals are brought 



