400 MR. G. E. H. BARRETT-HAMILTON ON [Apr. 3, 



Skull. The skulls of adult British examples do riot usually 

 exceed 26 mm. in total length, the more usual length being 25 mm. 



Distribution. Great Britain, Ireland, and the Scotch Islands 

 (except the localities inhabited by other subspecies, such as St. 

 Kilda, part of Lewis (Outer Hebrides), Barra, parts of the West 

 of Ireland, probably Shetland, and the sporadic localities occupied 

 bv M. s. wintoni) ; the Channel Islands (Alderney), Holland, 

 Belgium, Brittany, and North-west France, parts of Switzerland, 

 and perhaps portions of South-western France ; but the exact 

 limits of the distribution of this form are uncertain, and it is not 

 known whether its range is clearly marked off from, or whether it 

 intergrades with, the larger forms. 



General Remarks. Excluding examples of M. s. wintoni, I do 

 not find amongst specimens from the mainland of Great Britain 

 any tangible local differences ; but to insure satisfactory results 

 in this direction, a very carefully collected set of specimens from 

 several selected localities would be necessary. The skins from 

 Oxfordshire and Leicestershire (both those in Mr. de Wiuton's 

 and those in the British Museum collection) certainly seem 

 brightest and reddest, but they are summer skins, and there is no 

 conclusive series from other localities of exactly the same date 

 with which to compare them. Further, an old nursing female 

 taken in Glamorganshire in July is as hrightly coloured as any of 

 them. Again, specimens from the London Parks are, like the birds 

 and Lepidoptera, ver? dark and smoky. I am not, however, quite 

 ^able to trace beyond dispute any local British variations, other 

 than those already mentioned, but the subject is of great interest 

 and well worthy of the attention of British naturalists. Certainly, 

 if there be any reliable conclusions to be drawn from recent work 

 on the colour of mammals, the mice of Central England should 

 be on the whole brighter and redder than those of the surrounding 

 districts ; but a study of them should be based not upon individuals, 

 but on averages, and would need very careful procedure. It is 

 at least confirmatory of rny supposition' that amongst the more 

 remarkable individual skins which I have examined are an old 

 nursing female from Clifton, in which there was a thick median 

 line of yellow on the belly, and a male from Northumberland 

 (December), in which the belly is dirty white and exhibits also 

 a buff median line. I have not been able to separate Scotch 

 from other British specimens. 



As regards continental forms, it is probable that the further 

 accumulation of specimens will show the existence of hitherto 

 undetected subspecies. Thus, while those both from Brunswick, 

 Germany, and from Belgium belong to a type which, like M, s. 

 intermedins generally, may be distinguished from most Scandina- 

 vian specimens by their clearer colour both above (grey) and below 

 (white), I fancy that, of the two, the Belgians are the less clearly 

 white-bellied. Swiss specimens, on the other hand, seem to agree 

 with those from Upsala, Sweden, in having the central dorsal 

 region darker and more accentuated, and the underside duller, 

 while those from Bergen, Norway, are redder. 



