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229 
Antiqua consisting entirely of 3-4 moulter, or again of 45 moulter, or of 4moulters 
only? Do such species in any way occupy an intermediate position between others 
moulting, on the one hand, four times, and, on the other, five times as a fixed 
number ? 
Several species which hibernate in the larval stage, are known or believed to 
vary in the number of moults, and hairy larve which are said to vary in the num- 
ber of moults, include many species that hibernate as larve. It is, therefore, of 
interest to note that O. Antigua, though not hibernating, is closely related to 
several species that do so, such as the O. fascelina, common on northern moors, 
and the allied Arctia species which is believed to pass more than one winter in the 
larva state. 
If hibernation and variation in moulting are related, it would appear pro- 
bable that the additional moults are a provision for prolonging the duration of the 
feeding period after an exceptionally bad time during the winter, and that the 
number of moults in any individual may vary according to its requirements deter- 
mined in this manner; or, on the other hand, a less number of moults may repre- 
sent what occurs in many species, viz., a rush to reach the perfect state as early as 
possible, and so escape hibernation, and to become double-brooded. 
This suggests the inquiry whether the summer-broods of such species as 
Lunaria and Illunaria, which are smaller than the type and have been described 
as distinct species, moult as often as the autumn brood. 
Further investigation thus promises to throw valuable light on several ques- 
tions concerning variability. An isolated observation on the rare Acronycta alni 
bearing on this matter may be worth mentioning. A few eggs were given me 
from which I reared five larve. In its first stages this larva is remarkable from 
its exact resemblance to the dropping of a small bird. On its last moult, a 
great transformation occurs, and it is now velvety black, with golden yellow dorsal 
lozenge-shaped marks and curious clubbed hairs. Now four of my larve moulted 
four times, but the fifth moulted rather earlier than the others, so as to gain two 
days in four moults, in moulting the fourth time did not assume the adult livery, 
but was still in the bird-dirt stage, though larger than its fellows in that stage, 
and possessing the full complement of clubbed hairs, although they were pale and 
slender. It moulted an additional, or fifth time, and then assumed the adult 
plumage, and was larger than the others were, and had the clubbed hairs one 
millimetre longer than theirs, and remained feeding four days longer. 
