MURID^ 379 



(C) Tail about as long as head and body : — 



(a) Size smaller (maximum of head andl 



body about 75, of hind foot about \(i\MICROMYS minutus. 

 mm.) .... .J 



(b) Size larger (minimum of head and body 



about 75, of hind foot (rarely) 16 

 mm.) : — 



(a') Hind foot 16-19 "i™- • • MUS. 



(a) Colour of under side markedly] 



lighter than that of upper side, \m. muralis (St Kilda). 

 hind foot broader (4 mm.) .J 



(b) Colour of under side not mar-"j 

 kedly lighter than that of upper , , 



side, hind foot narrower (3-3-5 f^«^ musculus. 

 mm.) . . . .J 



(b') Hind foot 20-26-5 mf"- • • 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.). 



(a') Under parts white : — 



(a) With a collar-like chest-l . j, ■ „■ . . ■ 

 ^ ' \A.flavtcolhswtntom, 



(/?) Without a collar-like chest-\^. fridariensis (Fair 

 spot . . ./ Island). 



(b') Under parts more or less 

 washed with buff or brown : — 



(a) Under parts not so heavily\^. hebridensis (Outer 



washed . . ./ Hebrides). 



(/8) Under parts heavily washed A. hirtensis (St Kilda). 



II. TEETH AND SKULLS:— 



T i/r j-u 1 , f . u , . .u -c {MUSCARDINUS 



I. Mandibular angle perforate ; cheek-teeth 16 .| avellanarius. 



II. Mandibular angle imperforate J cheek-teeth 12: — 



I. Skull angular; cheek-teeth with prismatic 

 crowns : — 



(A) Palate simple, with shelf-like posterior\ _ „^ „^ 3^ vc 

 edge; cheek-teeth rooted . "^Ji^yuiUMV^. 



(a) nfi with two internal infolds . . E. glareolus. 



(b) nfi with three internal infolds : — 



(a') Brain-case smooth and convex . E. alstoni (Mull). 



, ,, „ . „ , {E. skomerensis (Skomer 



(b) Bram-case flattened . •■! Island). 



