158 Mr, M. A. C. Hinton on 



6. Microtus clarkeij sp. u. 



S . 170, 174; $ . 168, 175. Kiu-chiang-Salween divide; 

 latitude 28° N. Altitude 11,000'. 



A large vole related toM. calamorum, Thos. Size rather 

 less than in true calamorum, and considerably less than 

 in c. s2-iperus ', the hind foot in adults about 21 mm., and 

 condylo-basal length about 28*5. 



Essential external characters nearly as in calamorum. 

 Fur very soft and fine, though rather short (about 12 mm. on 

 rump). Ears distinctly visible above the fur. Tail about 

 half the length of the head and body. Soles with five 

 plantar pads only, completely naked from the heels forward; 

 claws of hands and feet about equal. A flank-gland some- 

 times present in males (No. 170, right side). 



General colour above nearly as in calamorum, viz., dark 

 brown (near "bistre^' of Ridgway). Under surface much 

 less white, the ventral hairs having their basal three- 

 fourths deep slate, and only their tips silver. Flank line of 

 demarcation regular, but not sharply defined. Upper surface 

 of tail brownish, not much lighter than the back; its lower 

 surface, together with the upper sides of the hands and feet, 

 dirty white. 



Skull smaller than that of either true calamorum or 

 c. superus, with the brain-case relatively broader and more 

 depressed. Interorbital region narrow with a weak sagittal 

 crest in old age, formed by the fusion of the temporal ridges. 

 Palate with the median posterior sloping septum broader, 

 less well defined, and shorter in adults. Bullae as in cala- 

 morum^ with a weak development of spongy bone within. 



Cheek-teeth essentially as in calamorum (figs. 13 & 14). 



Dimensions of the type, measured in the flesh : — Head 

 and body 130 mm. ; tail Q^ ; hind foot 21; ear 14. 



For skull-measurements, see table at p. 159. 



Type. Adult female. B.M. No. 22. 12. 1. 46. Original 

 No. 175. Collected by Mr. G. Forrest on July 24, 1921, 

 upon the divide between the Kiu-chiang and Salween 

 Kivers in latitude 28° N. Altitude 11,000^ 



Hah. As above. 



The discovery of this species, which 1 have much pleasure 

 in nam-ing after Colonel Stephenson B. Clarke, C.B., D.S.O., 

 is a matter of considerable interest. It and M. calamorum 

 belong to a group of voles which seem to link the water- 

 voles Arvicola with some of the larger species of '''Microtus'^ 

 inhabiting North America. The precise status of these 

 Far-Eastern voles is, however, a matter for further 

 investigation. 



