732 



RODENTIA— MURID^ 



(^1) 



(^2) General dorsal colour darker, with 

 noticeable suffusion of black towards 

 the rump, tail shorter, averaging 

 about 90 per cent, of the length of 



head and body 



Size larger (head and body more than 



100, hind-foot more than 23 mm.). 

 (a^) Head and body 129, hind -foot to 

 26.5 mm. 

 Coronoid processes of mandible 



normal 



(5^) Head and body to 115, hind-foot to 

 26 mm. 



Coronoid processes of mandible 

 exceptionally short and slender. 

 (a^) Angular processes of mandible 

 normal. Pectoral spot entirely 

 absent or vestigial, tail conspicu- 

 ously bicoloured, relatively long 

 (averaging 94 per cent, of the 

 length of the head and body. 

 (a*) Head and body to 115, hind- 

 foot to 25 mm. 



(6*) Head and body 

 foot to 26 mm. 



to 104, hind- 



sylvaticus butei (Bute). 



hirtensis (St Kilda). 



{b^') Angular processes of mandible 

 much elongated. Pectoral spot 

 constantly present, though small, 

 tail not conspicuously bicoloured, 

 relatively short (averaging 90 per 

 cent, of the head and body 

 length). Head and body to no, 

 hind-foot to 25 mm. . 



fridariensis fridariensii 

 (Fair Isle). 



fridariensis thuleo 

 (Foula). 



fridariensis graniii 

 (Yell). 



{b) Skull with strongly developed temporal 



ridges and angular brain-case, incisive 



foramina relatively short, their length 



being 19.3 to 21 per cent, of the condylo- 



basal length. 



Pectoral spot large, usually extended 



laterally to form a well-marked collar. . flavicollis wintoni. 

 (B) Skulls of adults with post-molar region relatively short; the distance 

 between a condyle and mj, equalling 45 to 47.1 per cent, of the condylo- 

 basal length, the average value of this dimension never more than 46.23, 

 per cent, and usually less than 46 per cent, of the condylo-basal length. 



