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Show 400 MR. G. E. H. BARRETT-HAMILTON ON [Apr. 3, Skull. The skulls of adult British examples do not usually exceed 26 m m . in total length, the more usual length being 25 m m. 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 by 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 31. 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 Winton'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 brightly coloured as any of them. Again, specimens from the London Parks are, like the birds and Lepidoptera, verv dark and smoky. I am not, however, quite able to trace beyond dispute anjr 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 m y 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 yeliow 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, aud from Belgium belong to a type which, like 31. s. intermedins generally, may be distinguished from most Scandinavian 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. |