MURID 379 
(C) Tail about as long as head and body :— 
(a) Size smaller (maximum of head and 
body about 7 Ss of hind foot about 16;M@7CROMYS minutus. 
mm.) . J 
(B) Size larger (qdtetenutn of head ed body 
about 75, of hind foot (rarely) 16 
mm.) :— 
(4’) Hind foot 16-19 mm. : US. 
(a) Colour of under side ae 
lighter than that of upper side, -AZ muradis (St Kilda). 
hind foot broader (4 mm.) | 
(b) Colour of under side not mar- 
kedly lighter than that of upper 
side, hind foot narrower (3-3° S 
mm.) , 
(z’) Hind foot 20-26°5 mm. . . APODEMUS. 
(a) Size smaller (head and body 
about 95, hind foot about 22 
mm.) . ; . . A. sylvaticus. 
(b) Size larger (head and body to 
about 126 mm., hind foot to 
about 26°5 mm.). 
-Mus musculus. 
(a’) Under parts white :— 
(a) With a collar-like chest- ‘| A. flavicollis wintont. 
spot 
(B) Withoutacollar ike chest- He fridartensis (Fair 
spot Island). 
(b’) Under parts more or less 
washed with buff or brown :— 
(a) Under parts not so heavily\ 4. Aebridensis (Outer 
washed. al) Hebrides). 
(2) Under parts Healt Piste A. hirtensis (St Kilda). 
Il. TEETH AND SKULLES:— 
I. Mandibular angle perforate ; cheek-teeth 16 A Sind aareee & 
II. Mandibular angle imperforate ; cheek-teeth 12 :— 
1. Skull angular; cheek-teeth with prismatic 
crowns :— 
(A) Palate simple, with shelf-like oaieea fs 
edge; cheek-teeth rooted EVOTOMYS. 
(a) m® with two internal infolds. . £. glareolus. 
(B) m§ with three internal infolds :— 
(a’) Brain-case smooth and conyex . £. alstoni (Mull). 
a skomerensis (Skomer 
(8) Brain-case flattened Island). 
