700 SCIURIDAE—SCIURUS 
Norway) that the Norwegian Squirrels (now referred to S. v. vulgaris 
and v. vartus) have similar moults to those observed in /eucourus. 
Thus the body-fur is shed and renewed twice a year—in spring and in 
autumn; the ear-tufts and tail-hairs only once—in the course of the 
summer. Though subject to considerable individual variation, the 
precise moment of change, as in England, appears to depend very little 
upon weather. At the autumn moult, the first grey hairs appear on 
the posterior half of the back; then they appear on the upper surface 
of the thighs and forepart of the back; later they spread over the 
flanks and fore-limbs; and lastly on the belly and inner sides of the 
thighs. The spring moult follows a converse order: the belly first 
becomes thin haired’; then the outer sides of the arms become red; next 
the flanks and inner surfaces of the thighs become yellowish-red; after 
this the grey hairs fall from the outer sides of the thighs, and lastly 
from the back, where in the neighbourhood of the rump long pendulous 
grey hairs can remain until a very advanced date. The colour-changes 
of the Norwegian animals are produced solely by the replacement of 
the old hairs by a new growth, and the bleaching process, so character- 
istic of the British species, is apparently quite unrepresented in them, 
as well as in the other continental races of S. valgarzs. 
Bleaching is known to occur also in Heliosciurus mutabilis, a species 
inhabiting Nyasaland (Thomas, P.Z.S., 1894, 140), and in Ratufa bicolor, 
a Giant Squirrel inhabiting Java (Bonhote, 4.17.V.4., [7] v. 490). In 
leucourus, as pointed out by Thomas, it “takes place mainly in the 
winter and early spring, so that it cannot be assigned to the special 
action of the summer sun.” Further, it affects only the annulated 
hairs with blackish-brown pigments, and not the unannulated hairs with 
rufous pigment; thus in “ February and March skins, the whole animal, 
from nose to tip of tail (but not the rufous limbs), is bleached to one 
uniform dull yellowish or drab tint” (Thomas, Zoologzst, 1896, 406). 
It seems probable from these facts that there is an important difference 
in the chemical constitution of the red as opposed to the blackish- 
brown pigment; the bleaching of the latter appears to be a process 
strictly comparable with that which we have described as taking place 
in the hairs of the House Mouse (azzéea, p. 643). 
It is of interest to note in conclusion that Collett (of. czt., 220) has 
described two distinct pelages of the young Norwegian Squirrels. 
According to him, nestlings first develop a red coat in which there is 
usually a more or less strong intermixture of whitish-grey hair, 
especially noticeable on the head and flanks. In this pelage, especially 
in Northern Norway (Finmarken), the grey tone may be as strongly 
evident as in the winter coat of many adults. This “nestling” pelage 
is changed apparently wholly or in part when the young are half grown, 
and it is succeeded by the true juvenal pelage, which is quite red. The 
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