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Show 1869.] MR. F. H.WELCH ON LEPUS AMERICANUS. 229 This Rodent is described in the 'New York Fauna' by De Kay; but I believe, up to the present time, no detailed account of the fur-changes in sequence to the seasons has appeared. Its representative among the European species is L. variabilis, the process of change in which is summed up in the ' Naturalists' Library' (vol vii.) as follows:-"From the examination of individuals at different periods of the year, I have inferred that in this species the hair is almost always changing; that in April and May there is a general but gradual shedding, after which the summer colours are seen in perfection ; that towards the middle of autumn many new white hairs have been substituted for coloured ones ; and that by degrees all the hairs and under-fur are shed and renewed before the end of December, when the fur is in the perfection of its winter condition, being closer, fuller, and longer than in summer." In the 'Edinburgh Philosophical Journal' (vol. xi. p. 191) the conclusion arrived at is that " during the whole of this remarkable change in the fur no hair falls from the animal; hence it appears that the hair actually changes its colour, and that there is no renewal of it." Thus, in the former article the change is attributed to an autumnal shedding and new winter growth ; in the latter to a change of colour only in the existent hair. I propose in the following remarks to enter fully into the details of the process, as illustrated by Lepus americanus. In order to appreciate fully the cycle of changes in the coat of this Rodent in sequence to the rotation of the seasons, it seems best to take the summer dress as our starting-point, and inquire into the varieties of hair entering into the composition of the fur at this period, for the better elucidation of the part each individually plays in the subsequent phases; for in scientifically inquiring into the change of colour in the fur-bearing animals, it is essentially necessary to make a clear distinction between that resulting from alteration of colour in the already existent coat, and that consequent on a fresh undergrowth, which by gradual increase may eventually obscure the summer and autumnal hues. Each portion also of the skin must be separately examined, and individual peculiarities noted. The summer dress may be described as follows:-Back and sides of a glistening fawn-colour, interspersed with black, especially over the vertebral ridge; tail white; face and ears reddish brown, sparsely variegated by black hairs; edges of ears externally black or dark brown, increasing towards the tips ; internally whitish, especially posteriorly ; whiskers and eyebrows black ; margin of lids dark brown or black, pupil the same, iris yellow; underparts white; anterior surface of feet light brown, the treading surface dirty white with hair very wiry. On examination, the components of this coat will be found to vary according to the portion of the animal examined ; consequently it is necessary to enter somewhat into details. In the fur are to be distinguished the external firm hairs constituting the pile and determining the colour, and the soft woolly undergrowth constituting the thickness of the coat and mainly instrumental in the retention of the animal heat. On the back the pile is made up of firm, straight, pointed hairs of diminished thickness PROC. ZOOL. Soc-1869, No. XVI. |