NOTES ON THE MICE OF ST KILDA 125 



Macleod. On the island of Dun, where the grass is very 

 luxuriant, hirtensis was found dwelling in fissures and holes 

 in the face of rocks, where grass was growing close by on 

 ledges or at the foot of the crags. Here signs of their 

 presence were manifest in the shape of the seeds of grass 

 on which they feed, and in their numerous runs. The seeds 

 of Carcx flava were found in a hole a few inches deep on 

 a hillside in Hirta, and perhaps forms the chief food. This 

 mouse is much addicted to cannibalism, and this led 

 to many specimens being completely destroyed before the 

 traps could be visited. So far as our observations were 

 concerned, this animal appeared to be entirely nocturnal in 

 its habits, no examples being seen abroad during the daytime. 



No young were secured during September 1910 which 

 were less than half-grown, and no pregnant females were 

 obtained. In September 191 1, however, several quite 

 young examples were taken, and on the 14th a gravid 

 female the first captured was trapped and found to 

 contain seven foetuses. Another, and younger female, with 

 six less-developed foetuses, was captured on the iSth. The 

 females in milk obtained during both visits varied a great 

 deal in size, some being evidently quite young creatures. 



The collection contains sixty specimens (males and 

 females) of this species, and as a result of the examination 

 of these, it becomes necessary to make some modifications 

 in the description of the animal. That the underparts of 

 hirtensis are heavily washed with yellowish brown has 

 hitherto been deemed an important characteristic of the 

 species. This is not the case, however, for in the majority 

 of adult specimens, and many of the immature ones, the 

 throat, chest, and abdomen are white, and only washed with 

 brown along the narrow median ventral line. As a result, 

 the demarcation between the peppery reddish brown upper, 

 and the pale under surface is pronounced in most examples, 

 and renders the species very similar to the familiar Long- 

 tailed Field Mouse {Apodemus sylvaticus). About one-third 

 of the adults and the majority of the younger specimens have 

 the under surface more or less strongly washed with yellowish 

 brown. 



