222 JOURNAL, NATURAL IIL^T. SOCIETY OF SLIM VoL L 



Under-surface to tlie bases f)f the hairs, wliite, fairly clearly?' 

 inai'gined, and continuous down the thighs to the hind-feet whicli are 

 conspicuously pale. Tail dark throughout. 



Skull and Teeth. HardI}' difi'er from those of mainland animal 

 except that the cranium seems to be rather narrower or more pear- 

 shaped, owing to the closer approximation of the parietal ridges while 

 the sides of the cranium are less vertical. 



Measurements. Ears of type, 24, of tlie series, 22-21- mm. 



For other measurements see taljle p. 223. 



Specimens examined. Thirteen, all from Koh tSi Chang. 



Reinarls. Tiie light upper surface closel^^ resembling in colour 

 the back of some races of swrifer rats markedly separates this form 

 from the much daiker, duller miinland animals. This bright back 

 and. the pure white under surface seem further to be present at all 

 ages, as young individuals do not differ from adults. 



Epimys rattus poenitentiarii, subsp. nov. 



Ttjpe. Adult male (skin and skull) No. 1966/0. B. K. Collect- 

 ed on Koh Phai, Inner Gulf of Siam, 1st February, 1915. 



Diaijnosis. Colour like E. r. partus but size ratlier smaller. 

 Skull like that L. r. partus but with bullae markedl}' smaller and less 

 dilated than is the case both with it and with the mainland animal. 



Measurements. Ear of type 23, of series 21-23 mm. 



For other measurements see table p. 224. 



Specimens examined. Fifteen all from Koh Phai. 



Remarhs. Besides being a rather less robust animal the cons- 

 picuous difference in size and form of bullae compel separation of this 

 animal from that of Koh Si Chang and the mainland. 



