244 EODENTIA. 



>S'. keraudrenii, S. splendidus, S. cinnamomeus, S. siamensis, S. splendens, S. germcmii 

 S. bocourtii, and S. leucogaste7\ The extreme limit of their range is from Assam in a 

 south-easterly direction through Burma and Siam to the Islands of Pulo Condor 

 and Sichang. The colour of their fur is most diverse, varying from deep maroon- 

 chestnut to red, and from grey- grizzled to intense black and to pure white, while 

 others are spotted with brown on a white ground. In all of these squirrels the 

 relative proportions of the parts are the same, but all the grizzled forms are small, 

 and their skulls prove that they are young. These immature forms are S. siamensis, 

 Gray, and S. leucog aster, A. M. -Edwards. S. ferrugineus, S. keraudrenii, S. cinna- 

 momeus, and S. splendidus are all rich red squirrels, while S. germani is a jet black 

 and 8. finlaysoni a pure white form ; whereas S. bocourtii is also white, but marked 

 by great brown spots. These differently coloured squirrels are thus far distinctive 

 of localities or rather of geographical areas; none but the pure red forms have 

 been found to the west of Assam and Burma. All the other phases or varieties are 

 apparently confined to Siam. 



As I have personally studied the types of all these supposed species, I propose 

 to indicate their leading features and those tendencies which they show towards 

 specific unity. 



The type of *S'. finlaysoni was obtained in Siam by Dr. Einlayson, and another 

 was procured by the same traveller in Sichang Island off the coast of Siam. 

 These two specimens are exactly alike, being white squirrels with a yellowish tinge. 

 The feet, however, show a tendency to become dark or even blackish, especially on 

 the toes, which is a character of the red form of Assam and Burma, while it is 

 seldom observed in the red squirrels of Siam. A few of the hairs on the head and 

 tail have black tips, but their presence makes little impression on the pale fur, except 

 on the tail. The whiskers are black. In other specimens from Siam, however, I 

 have observed the white fur generally so intermixed with black hairs that a 

 remarkable grey colour was communicated to the squirrels presenting this pecu- 

 liarity. In these forms, the black occurs chiefly along the upper surface of the 

 back, on the shoulder, outside of the fore limbs and thighs, and on the proximal third 

 of the tail ; the under parts being pure white. Erom the profusion with which 

 these black hairs occur, the production of the black S. germani is only a question 

 of degree, and, as it does not involve any structural difference between the two, but 

 is solely brought about by the deposit of black pigment to a greater extent 

 than in S. finlaysoni, there seems no reason why these white and black squirrels 

 should be regarded in any other light than varieties. 



There is much greater difficulty attending the verbal explanation of the re- 

 lations that exist between S. bocourtii and S. ferrugineus, but some additional fight 

 is thrown on them by considering the forms which have been referred to S. siamensis 

 and /S'. leucogaster, both of which are young squirrels. 



With regard to S. bocourtii, this squirrel can be best described as a piebald 

 S. finlaysoni. It is also from Siam, and is distinguished by the following leading 

 features^ which are subject, however, to considerable variation. The rich brown of 



