MR. M. A. C. HINTON ON HEBRIDEAN MAMMALS. , 829 



General characters. — This mouse is a little larger than E. 

 glareolus, approaching U. norvegicus, but the tail is shorter than in 

 the latter, and about as in glai'eolus ; smaller than E. skomerensis 

 or ccesarius. The ears are about as in E. glareolus. The hind 

 feet are as in norvegicus and skomerensis. 



Cranial and dental characters. — In size the skull is larger than in 

 E. glareolus and agrees with that of norvegiciLS. As in the latter 

 form, the jugals are heavy, but the curvature of the zygomatic 

 arches agrees with glareolus. The brain-case is very broad and 



Text-fio-. 137. 



Dorsal view and profile of skull of Evotomys ahtoni. Natural size. 



smoothly convex, the temporal ridges being but faintly indicated 

 even in aged skulls : the parietal region is convex in dorsal profile, 

 with the highest point a little behind the middle of the parietals, 

 instead of flattened ; these features impart an appearance of 

 relativel}'- greater cranial capacity than is seen in emj of the 

 other European species of Evotomys. The postorbital (squamosal) 

 processes are not conspicuous. The interorbital region is broad, 

 with a wide shallow median sulcus. The nasals are rounded 

 or slightly and narrowly emarginate behind, ending flush with 

 or slightly behind the ends of the premaxillse ; they are slightly 

 longer than the diastema, expanded in front, their lateral bordei-s 

 slightly but distinctly concave. The rostrum is shallow, as in 

 E. norvegicus, its least depth behind the incisors not exceeding 

 the anterior width. The bullae are nearly as in norvegicus. The 

 last upper molar has a third inner fold and fourth inner salient 

 angle — the latter being usually well developed. 



The colour is much darker than in E. skomerensis, but is very 

 similar to that of E. glareolus, being deep russet above ; the under 

 side is richly washed with yellowish or bufi". 



This is an interesting and quite distinct species, recognizable 

 externally by its generally large size combined with small ears 

 and short tail, while in addition its skull characters are quite 

 distinctive. On the whole it makes a nearer approach to E. nor- 

 vegicus than to any other species of Evotom]/s. 



