424 MURIDAE—EVOTOMYS 
ex panded in front, with their lateral borders slightly but distinctly 
concave. The rostrum is shallow, as in £. norvegicus, its least depth 
behind the incisors not exceeding its anterior width. The auditory 
bulla are about as in xorvegicus. m* has a third inner infold and a 
fourth inner salient angle, the latter usually well developed. 
Skull:—Length, condylo- basal, 24-1 to 25-3; of nasals, 6-8 to 
7:8; of diastema, 6-3 to 7-7; of mandible, 15-1 to 15-7; of maxillary 
tooth-row, 5-2 to 5-7; of mandibular tooth-row, 5-1 to 5-4; breadth, 
zygomatic, 13-5 to 14-5; inter-orbital, 3-8 to 4-1; occipital, 11-4 to 12-1; 
depth, median occipital, 6-0 to 6-6. 
Status :—Alston’s Bank Mouse is, like 2. skomerensis, probably a 
relict of an ancestral form of large size which occupied Britain before 
the arrival of glareolus. Being allied to EF. nagert norvegicus of 
Skandinavia, it is the latest link in the chain connecting the mammals 
of Scotland and Skandinavia, and its existence is apparently another 
indication of a comparatively recent land-connection between the two 
countries. 
THE RAASAY BANK MOUSE. 
EVOTOMYS ERICA, Barrett-Hamilton and Hinton. 
1913. EVOTOMYS ERICA, G. E. H. Barrett-Hamilton and M. A. C. Hinton, Azza. 
and Mag. Nat. Hist., October 1913, 361: described from Raasay, near Skye, 
Scotland ; type specimen, No. 14.1.30.5 of British Museum collection. 
Distribution and History :—This mouse was discovered on the 
island of Raasay in April 1913 by Montague (see footnote, p. 422 
supra), who found it rather scarce; his three specimens were “trapped 
in big heather.” 
Description: — It resembles #. aéstont in general appearance 
and colour, but is slightly larger, has a more robust tail, and the ventral 
surface much more heavily washed with buff, in sharp contrast with 
the dark brown of the flanks and upper surface of the tail. 
The skull is distinguished from that of #. ad/stont by its much 
larger cheek-teeth, broader zygomatic arches, heavier jugals, more 
salient and extensive post-orbital crests, flatter parietals, narrower 
inter-pterygoid space, wider pterygoid fossa, vertical instead of 
ventrally divergent pterygoids, and auditory bulle with their antero- 
internal parts produced inwards as blunt points instead of being 
rounded. The mandible differs principally in its larger size, and in 
having the lower borders of the angular processes widened into broad 
surfaces for the insertion of the superficial parts of the masseter 
muscles: the width of these muscular facets is 1-4 mm. as against 
o-4 mm. in &, alstonz. 
The teeth are of normal form, differing from those of a@/stonz 
