RESULTS FROM THE MAMMAL SURVEY 



231 



forming a very conspicuous mark, while in other specimens from 

 the same localities this line is rednced, broken or altogether absent. 

 On this account Thomas's G. haringtoni solutus must be considered 

 a synonym of true haringtoni. 



On the other hand the characters that are of use are the general 

 colour of the upper surface, the extent of the facial light mask, whose 

 actual colour is of less constancy, and the general coloration of the 

 tail. Even these are, of course, variable to a certain extent, but the 

 series we have been privileged to examine shows a sufficient average 

 constancy in them to justify our using them for subspecific distinc- 

 tion. 



The following are the collecting stations at which these squirrels 

 were obtained, with their approximate distance from Hkamti south- 

 wards in miles, following roughly the course of the river, biit not 

 its smaller windings : — 



26°-5' N. 95°-55' E. 

 25 miles S. of Hkamti. 

 50 

 65 



Hkamti 



Kauktaung . 



Minsin 



Tamanthe 



Maungkan . . . ... ... 85 



Homalin ... ... ... 105 



Pyaungbyin ... ... 140 



Kindat 180 



Yin 250 



The range in altitude is not great, only some 300 feet in all. 

 Of these nine stations only two do not have a peculiar form of G. 

 sladeni, Kauktaung having one practically the same as that of 

 Minsin, while those of Maungkan and Homalin are also quite the 

 same. We therefore get from Hkamti to Kindat a definably 

 different form on the average every thirty miles, a longer distance 

 (70 miles) separating the seventh subspecies at Yin from that of 

 Kindat. 



How far this remarkable plasticity compares with that of other 

 mammals elsewhere we have no material to judge, but a reference may 

 be made to the Traguli of the Rhio Linga Archipelago worked out 

 by Mr. G. S. Miller.* There, while the great areas of Sumatra 

 and the Malay Peninsula only have one form of a certain type, 

 the little Archipelago, about a hundred and fiftieth of their extent, 

 has developed seven, but the problem of their causation is affected 

 by insularity, while the squirrels of the Chindwin have evolutioniz- 

 ed in a continuous land area. 



To what distance eastwards from the river the different sub- 

 species range remains to be proved. Some at least extend to the 

 Irrawaddy, but whether down the west side of that river the whole 

 seven will again be found we can at present express no opinion. 



* Proc U. S. National Mus. 37, p. 1. pts. 1-3, lOOtl. 



