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 per- 
fection ; 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 Decem- 
ber, 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 séquence 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 under- 
growth, 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;*in- 
creasing 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 con- 
stituting the pile and determining the colour, and the soft woolly 
undergrowth constituting the thickness of the coat and mainly in- 
strumental in the retention of the animal heat. On the back the pile 
is made up of firm, straight, pointed hairs of diminished thickness 
Proc. Zoou. Soc.—1869, No. XVI. 
