732 RODENTIA—MURID® 
(2°) General dorsal colour darker, with 
noticeable suffusion of black towards 
the rump, tail shorter, averaging 
about go per cent. of the length of 
head and body. 
(5!) Size larger (head and tei more oes 
100, hind-foot more than 23 mm.). 
(a?) Head and body 129, hind-foot to 
26.5 mm. 
Coronoid processes of mandible 
normal. 
(6°) Head and body to ea fae foot to 
26 mm. 
Coronoid processes of mandible 
exceptionally short and slender. 
(a8) 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 to 104, hind- 
foot to 26 mm. 
(28) 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 110, 
hind-foot to 25 mm. . 
(2) 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. 
sylvaticus buter (Bute). 
hirtensts (St Kilda). 
Jridariensts fridartensis 
(Fair Isle). 
Jridariensis thuleo 
(Foula). 
Jridariensis grantit 
(Yell). 
. flavicollis wintont. 
(B) Skulls of adults with post-molar region relatively short; the distance 
between a condyle and m3 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. 

