542 MURIDAZ—APODEMUS 
the crofts. Some fine specimens were captured in a store close to the 
water’s edge. On the island of Dun it was found dwelling in fissures 
and holes on the face of the rocks, where the very luxuriant grass was 
growing close by on ledges or at the foot of the crags. Here its 
presence was betrayed by its numerous runs, and by the seeds of grass 
on which it feeds. Seeds of Carex flava were found in a hole a few 
inches deep on a hillside in Hirta; these seeds form perhaps the 
chief food. It appears to be much addicted to cannibalism; because of 
this, many specimens were completely destroyed before the traps could 
be visited. It appeared to be entirely nocturnal. Like sy/vaticus and 
other mice, it attains sexual maturity at an early moment; the nursing 
females caught in September 1910 and 1git varied greatly in size, 
some being evidently quite young creatures. In September 1910 no 
pregnant females and no young smaller than half-grown were taken. 
In September 1911 Mr Eagle Clark obtained several quite young mice. 
A female caught on 14th September contained seven foetuses; another 
younger one taken on the 18th, had six less developed foetuses. Mr 
Waterston describes two nests, “neither of them typical.” He found 
males twice as numerous as females. Dissections showed the average 
number of foetuses to be six. Both sexes appeared to be subject to 
disease, especially of the liver, which was spotted by colonies of 
coccidia, and also infested by a Cestode. The people said that on Dun 
these mice are subject to variation in colour, and one with some white 
markings was brought to Mr Waterston. 
THE FAIR ISLE BIEED MOUSE: 
APODEMUS FRIDARIENSIS (Kinnear). 
Synonymy under sub-species. 
Distribution :—Fair Isle and Shetland Islands, where it occurs on 
Yell, and possibly on Mainland. 
History and status:—This Field Mouse was discovered on Fair 
Isle by Kinnear, who described it in 1906 as a sub-species of A. sy/vaticus. 
In his Catalogue Miller has accorded this form full specific rank. 
The differences between /rzdartensis and sylvatecus are scarcely such as 
would entitle the former, if it stood alone, to be considered as anything 
more than a sub-species of the latter. In the summer of 1913, 
Ogilvie-Grant found a Field Mouse living on the island of Yell. 
His specimens, although differing from typical /rzdarzensis in some 
respects, are clearly more nearly related to the Fair Isle mouse 
than to A. sylvatzcus, and they have been described as a sub-species 
(4.7 grantiz). A large Field Mouse also occurs on Mainland, Shetland, 
and this, when better known, will probably be found to belong to 
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