268 MICROTIN^ 



Range. — Japan, including the islands of Kiushiu, Shikoku, 

 Hondo, and Hokkaido. 



Characters. — A long-tailed, dark-coloured form with diffuse 

 mantle. 



Size as in other subspecies, hind-foot in adults to 21 mm., 

 condylo-basal length of skull to 28-5 mm. or more. Fur soft, 

 moderately long and dense, attaining a length of about 10 mm. on 

 the back. Tail relatively longer than in E. r. rufocanus ; usually 

 from 40 to 50% of the head and body length ; thinly clothed with 

 short stiff hairs, the annulations plainly visible in summer, nearly 

 concealed in winter; terminal pencil very short and thin. 



Colour dark, varying considerably with age, but always much 

 less rufous above than in E. r. rufocanus. Mantle diffuse, covering 

 the whole upper surface in young in post-juvenal pelage, but less 

 extensive and rather better defined in subadult and adult speci- 

 mens, although never becoming so restricted and so sharply con- 

 trasted with the surrounding parts as in the typical subspecies. 

 In adults, although the tips of the ears are concolorous with the 

 flanks as in E. r. rufocanus, the mantle extends forwards over the 

 muzzle and invades the cheeks, instead of being confined to the 

 area between the eyes and between the ears, and behind it fully 

 covers the rump. In colour the mantle is yellowish- rather than 

 reddish-brown, and more or less inconspicuously darkened by 

 long black hairs and dusky hair-tips, its precise hue ranging 

 between russet and dark chestnut. Some young specimens are 

 much darker, their dorsal colour approaching dark vandyke-brown. 

 Cheeks and flanks paler and greyer in adults; not conspicuously 

 greyer than the back in immature specimens. Under surface not 

 sharply defined, grey more or less heavily washed with ochraceoua- 

 or cream-buff. Hands and feet grey above, the digits sometimes 

 whitish ; soles hairy between the heel and pads. Tail more or less 

 distinctly bicoloured, brown above, greyish or whitish below. 



Skull when adult distinguished from that of E. r. rufocanus 

 by its longer and narrow braincase, and by its more extensive but, 

 in dorsal view, less conspicuously salient post-orbital squamosal 

 crests. Skulls of young specimens (condylo-basal length 22-5-25-5 

 mm.) much resemble those of normal species of Evotomys. The 

 superciliary ridges, if developed at all, are feeble and confined to the 

 margins of the orbits in specimens measuring less than 24-5 mm. ; 

 in later stages they become .stronger and approach each other 

 slowly, the anterior ends of the ridges being first to show signs 

 of approximation ; later and gradually the movement affects the 

 whole ridge on each side, so that the ridges become parallel 

 throughout, instead of being anteriorly convergent ; in the oldest 

 skull examined (condylo-basal length 28-5 mm.) they are moder- 

 ately strongly developed, parallel, and separated from each other 

 merely by an interval of 1-9 mm. 



The cement spaces of the cheek-teeth (m-) may show signs of 

 closure when the condylo-basal length amounts to no more than 



