1900.] MUS SYLYATICUS AND ITS ALLIES. 399 



the only seasonal 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, bat 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 Mus musculus ; others 

 are slate-grey, and one from Shetland has the upperside like that 

 of typical musculug and the underside white. Some very young 

 specimens lack the line of demarcation between the colours of the 

 upper and under surfaces and 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. AV. E. de AVinton and myself, consisting 

 chiefly of specimens taken in the months of May and 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 September by Mr. AY. R. Ogilvie 

 Grant in Elginshire, Scotland, and on the 8th October at South 

 Sutor, Cromarty, Scotland, and of the form M. s. wintoni on 

 Dec. 7th, by Mons. A. Robert 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 M. s. princeps 

 and pigmies like J/, s. celticus or M. s. tauricus. 



