54 MR. J. L. BONHOTB oif [Feb. 5, 



Type C. Sc. leucocephalus Grray, 



a. 6 ad. sk. Cheimat, E. Menam ; alt. 20 m. 21st January, 

 1900. 

 Type D. 8c. harmandi M.-Edw. 



' h,c. 6 2 ad. sk. Kampeng, E. Mu Ping ; alt. 110 m. 3rd 

 February, 1900. $ pregnant with two young. 



I have again been most carefully through the series of this 

 Squirrel in the Museum, and there seems but little doubt that we 

 have here a true instance of a polymorphic species. Without 

 going into the outlying forms, four distinct types may be found in 

 Siam, and are, in fact, all represented among the specimens in this 

 collection. They have all received names at various times, but I am 

 unable to recognize their title to specific or subspecific rank. 



Type A. The true Sc. finlaysoni is pure white all over, with 

 the soles of feet and eyes black. 



Type B {Sc. sjolendens) is of a uniform bright chestnut 

 throughout, and, according to Mr. Lyle, is found in 

 regions where the earth is similarly coloured. 



Type C {Sc. leucocephcdus) is of a grizzled brown above and 

 white below. 



Type D (Sc. harmandi) is similar above and chestnut 

 below ; but amongst these last two varieties every 

 possible mixture and combination is found. 



Apparently, although it must be understood that there is no 

 such thing as an invariable rule in dealing with this species, the 

 pure white (type A) and type C are found on the lower levels, and 

 as one ascends the river the tendency to red underparts increases. 



In the measurements of a series of skulls, they fall into two 

 groups, separable by their size alone ; the measurements of types 

 A and B average larger than the rest, but a few skulls intermediate 

 in size are also found to be those of indi^dduals intermediate in 

 colour. Furthermore, the skull of the type of Sc. finlaysoni, although 

 quite adult, is the smallest of any in the series. There is there- 

 fore at present no alternative but to consider the various races 

 as polymorphic forms of one species. 



It may perhaps be of use to-future workers if I add the average 

 measurements of part of the series of skulls and skins ; those im- 

 perfect in any of the measurements have been left out of the 

 calculation, although measured and taken into account in my 

 general remarks. 



Slcins in flesh : — 



Head and 

 body. Tail. Hind foot. Bar. 



mm. mm. mm. mm. 



•Types A & B [5 skins] . . 219-5 221 49 22 



Types C & D [16 skinsj . . 201 209 44 19-5 



