362 Messrs. Barrett-Hamilton and Hinton on new 



External characters. Like E. alstoni from Mull (Abstract 

 P. Z. S. no. 119, 15th April, 1913, p. 18) in general appear- 

 ance, but slightly larger and with very robust tail. The 

 underside is much more heavily washed with buff, and is in 

 sharp contrast with the dark-coloured flanks ; the under 

 surface of the tail is clear buff, and sharply contrasted with 

 the dark brown of its upper side. 



Dental and cranial characters. The cheek-teeth are of 

 normal form, but are much larger than in E. alstoni or most 

 other species of Evotomys, being scarcely smaller than those 

 of cossarius : ch.t. 3* has always a deep third inner fold 

 and usually a large fourth inner salient angle, but in no. 80 

 the latter is obsolete in the left tooth. 



The skull is most readily distinguished from that of 

 E. alstoni by its larger cheek-teeth, broader zygomatic arches, 

 heavier jugals (their upper borders boldly convex), more 

 prominent and extensive postorbital crests, less convex 

 parietal region, wider pterygoid fossse, with correspondingly 

 narrower choanpe, and vertical instead of ventrally divergent 

 pterygoids. The antero-internal part of each auditory bulla 

 is produced into a blunt point instead of being rounded. 

 The outer wall of the infraorbital canal is a little wider, the 

 rostrum rather deeper and narrower, with smaller and nar- 

 rower palatal foramina, the interorbital region slightly more 

 constricted, and the palate relatively wider. The mandible 

 is larger than in alstoni, its coronoid, condylar, and angular 

 processes noticeably more robust; its inferior border is much 

 thicker and the lower margin of the angle is broadened 

 throughout into a wide surface for the insertion of the super- 

 ficial part of the masseter muscle ; the width of this surface 

 is 1*4 mm., but in E. alstoni only 0'4 mm. For the cranial 

 dimensions see table on p. 363. 



Remarks. As we have pointed out elsewhere, E. alstoni is 

 of interest, since in our opinion it represents in a somewhat 

 modified form the type which in the late Pleistocene period 

 was dominant in Western Europe. This type appears to have 

 been ousted from the more favoured portions of its territory 

 by an incoming rival, E. glareolus ; and it survives only in 

 islands, on mountains, or in the less hospitable northern 

 districts. In each of such restricted stations it has suffered 

 more or less profound modification in coping with the demands 

 of purely local conditions, and therefore it is now represented 



* In this paper we write " ch. t.'' instead of the usual " m.," because 

 such a symbol is non-committal; in the opinion of one of us (see Proc. 

 Geol. Assoc, xxi. p. 490, 1910) the anterior cheek-teeth of Microtinse are 

 persistent '"milk-molars," and the formula dm. ^ m. p- 2 the correct one 

 for the group. 



