MAMMALS FKUM SIAM. 



55 



Specimens examined. — Eight from the type-localit3\ 

 Remarks. — This form is an intermediate stage between co7i- 

 nectens and eclipsis. The former in isolated individuals is 

 beginning to show the tendency towards increase in the yellow 

 areas, while in the present animal this, as well as the darker 

 coloration, is now well and constantly established. Both, how- 

 ever, still retain the normal bicolored tail. 



It is interesting to note that in this small group of islands two 

 opposite types of deviation occur : in E. s. changensis and Jcutensis 

 the trend is towards an increase of the abdominal white area, 

 while in this race and E. s. eclipsis it is the dorsal colour that has 

 spread until it reaches a climax in the last form in conjunction 

 with extreme dullness of tint and blackened tail. 



33. Epimys rattus, subsp. 



Mus rattus Bonhote, P. Z. S. 1900, p. 194; id., op. cit. 1901, 

 vol. i. p. 56 ; Flower, op. cit. 1900, p. 3G1. _ 



Mus raU'us rvfescens de Pousargues, Mission Pavie, Indo- 

 Chine, Etudes Diverses. iii. p. 528 (1904). 



Epimys rufescens Gyldenstolpe, Arkiv for Zoologi, Stockholm, 

 Band 8, No. 23, p. 18 (1914). 



I obtained at Ok Yam and Klong Yai a series of 13 rats, which 

 are apparently indistinguishable from the common Epimys raUus 

 of the Malay Peninsula, except that the white underparts more 

 frequently assume a light silvery shade. I have had no oppor- 

 tunity of comparing them with Epimys raUtts rohustulus (Blyth) 

 from Tenasserim, and therefore place them under the specific 

 name. The tail is longer than the head and body and slightly 

 paler below proximally ; the feet are whitish. 



One female from Ok Yam (No. 1797) is abnormal in having 

 the tail slightly shorter than head and body and concoloured, the 

 feet dark ; the upper side blackish brown and the underparts of 

 a colour intermediate between mouse-grey and neutral-grey. 



With these I would associate four examples from Koh 

 Chang Id. 



From the two islands, Koh Mehsi East and West, series of 13 

 and 15 respectively were obtained. While showing much varia- 

 bility among themselves, all are apparently conspecitic with tlie 

 above. They range from melanotic individuals having backs 

 strongly suffused with blackish brown to others having that 

 surface of warm grizzled-brown, while underparts vary from 

 Avhite to grey. 



This difference in colour is not a question of sex or age, for 

 though juveniles generally (not invariably) have greyish under- 

 sides, yet these are by no means of so dark a shade as the extremes 

 of the adults ; neither do the darker-backed individuals always 

 have darker underparts, though, again, this is generally the case. 

 The effect is to make the insular series much darker than the 

 mainland one, but as this character is apparently transitory, it 

 cannot be used for the purpose of differentiation. 

 Measurements. — See table, p. 75. 



