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Show 1900.] MUS SYLVATICUS AND ITS ALLIES. 399 the only seasoual difference which I can discover. The presence of the black-tipped hairs on the dorsal region gives the Mice the appearance of being more darkly coloured on the back and redder on the flanks ; but there is a good deal of variation, even amongst individuals from the same locality, in regard to the comparative darkness, greyness, or redness of the upperside. As a general rule, very old specimens seem to be the reddest, but I have seen very large ones which were remarkably grey. In many there is present a breast-spot of variable extent, which may in some cases extend backwards along the median ventral surface, either as a thin rufous line or as a rather broad and diffused yellowish staining of the belly. In old nursing females the underside often becomes very bare, and may lose its pure white colour. In immature specimens the coloured tips to the hairs are not well developed; hence young mice are always duller and more House-mouse-like on the upper surface. In some cases, as in that of a specimen from the Island of Skye, the colour, both above and below, is identical with that of typical 31us musculus; others are slate-grey, and one from Shetland has the upperside like that of typical musculus and the underside white. Some very }roung specimens lack the line of demarcation between the colours of the upper and under surfaces aud are dark-bellied, that is to say, the white-tipped hairs are absent and the dark underfur prominent; but this condition is not invariable, and many are comparatively brown or red, although not so much so as are the adults. My remarks respecting the colour of immature specimens are mainly based on the British series at the Natural History Museum and those in the collections of Mr. W . E. de Winton and myself, consisting chiefly of specimens taken in the months of May aud July : later in the autumn a pelage which more nearly resembles that of the adults is assumed. In mild climates young are born until late in the year, since two females trapped by Mr. Oldfield Thomas near Calais, France, in September were nursing ; other nursing females have been trapped as late as 10th 8eptember by Mr. W . K. Ogilvie Grant in Elginshire, Scotland, and on the 8th October at South Sntor, Cromarty, Scotland, and of the form 31. s. wintoni on Dec. 7th, by Mons. A. Bobert in Haute-Savoie. It would seem, then, that specimens in immature pelage may occasionally be trapped almost throughout the winter. Moult. The rarity of the specimens showing a moult is worth noticing, and I can only suppose that the change from one coat to the other is made gradually and in an inconspicuous manner. One of Mr. Thomas's August specimens from Holland, a male (no. 98.2.1.18), is moulting from the rufous to a duller coat, and has just a patch of the former colour on the rump, whereas the rest of the body is of a dull colour. Dimensions. The tables (p. 423) show that this subspecies is intermediate in size between giants of its race like 31. s. princeps and pigmies like 31. s. celticus or 31. s. tauricus. |