ST. KILDA AND ITS 13I1U)S. 355 



interested me most was the discovery which I made of a 

 small colony of Fork-tailed Petrels nesting, which had 

 not previously been known to the natives. 



The isolated position of St. Kilda would lead one to 

 anticipate that some modifications might be found in the 

 resident fauna of the district, and this anticipation is 

 realised. The Wren is a well known instance of this. 

 It is not, however, so generally known that the mice also 

 present distinct peculiarities as compared with the corre- 

 sponding mainland forms. I am indebted to Mr. 

 IsTewstead for calling my attention to the work that has 

 been done on this subject. Both our common mice, Mus 

 sylvaticus (field mouse) and Mus musculus (house mouse) 

 are represented by peculiar forms. The first specimen of 

 the peculiar field mouse of the island, which has received 

 the name of Mus hirtensis, was obtained and described by 

 Mr. Steel Elliott (5) in 1895 ; and in 1899 Mr. Barrett 

 Hamilton (6) published a paper treating exhaustively of 

 this species, and of the St. Kildan form of the house mouse, 

 which was described as a new species under the name Mus 

 muralis. Reference may be made to the above communi- 

 cations for a full account of these interesting new species 

 or sub-species; but I may here briefly state that the St. 

 Kildan field mouse (Mus hirtensis) is larger than the 

 ordinary form of M. sylvaticus, its back is more inclined to 

 grey, and the underside has a greater amount of buff or 

 yellowish brown colouration, and even in some cases a 

 slight rufous shade ; whilst M. muralis is also a larger and 

 more robust species than the common house mouse, the 

 colour of its back resembles more a dark specimen of 

 typical M. sylvaticus, while the colour of the under surface 

 is buff, separated by a well-marked line of demarcation 

 from the upper surface. There are also differences in the 

 skulls. 



