284 MICROTIN^ 



In this genus the size of the cheek-teeth seems to stand in 

 inverse proportion to the size of the auditory bullae, forms with 

 large bulte having small light molars and those with small bullae 

 large heavy molars. 



Remarks. — The relationships of Eolhenomys, which seems to be 

 an offshoot from some primitive Evotomys-Yike stock, are dis- 

 cussed in the Introduction. Twelve or thirteen forms are now 

 known from South-Eastern Asia, and these I have recently 

 referred to four species. The characters of these forms may be 

 " keyed " as follows : — 



Key to the species and subspecies of Eothenomys : — 



A. Anterior upper cheek-teeth complex; m^ with four, m? with 



three salient angles on the inner side. 



a. w? with four inner saHent angles. 



a^. m^ with four outer salient angles ; auditory bullae small, 

 cheek-teeth heavy. ColoiU' bright. 



E. melanogaster cachinus Thomas. 

 Kachin Province, W. Burma. 

 b^. m^ with three outer salient angles. 

 a^. Size normal ; condylo-basal length to 26 mm. ; hind- 

 foot to 19 mm. 

 a'. Bullae large, molars light. 



a*. Colour darker E. m. eleusis Thomas. 



Yunnan. 



b*. Colour brighter E. m. aurora Allen. 



Hupeh. 

 b^. Bullae small, molars heavy. 



a*. SkuU strongly bowed dorsaUy. Colour rather 



brighter E. m. miletus Thomas. 



W. of Yang-pi, Yunnan. 

 b*. SkuU normal, not bowed dorsally. Colour rather 



darker E. m. ccmfinii Hinton. 



Kiu-chiang-Salween Divide. 

 b". Size large; condylo-basal length 28 mm.; hind-foot 



20 mm. Colour bright .... E. fidelis Hinton. 



Li-chiang Range. 



b. vv' with three inner and tlu-ee outer salient angles. 

 a^. Bullae large, molars light. 



a^. Colour darker, bullae shglitly larger. 



E. m. melanogaster M.-E. 

 W. Sze-chwan. 

 6^. Colour brighter, bullae slightly smaller. 



E. m. columns Thomas. 

 N.W. Fokien. 

 b^. Bullae small, molars heavy. Colour very dark. 

 a-. Larger (hind-foot 19 mm.), with broad braincase. 



E. m. mucronatus Allen. 

 W. Sze-chwan. 

 b". Smaller (hind-foot 17 mm.), with narrow braincase. 



E. m. libonotus Hinton. 

 Mishmi Hills. 



B. Anterior upper cheek-teeth more or less simplified; m^ with 



only three inner saUent angles. 



