424 TRANSFORMATIONS OF INSECTS. 
the antenne. The head is carefully withdrawn through the opening 
in its covering, and with it the antenne and parts of the mouth, 
and afterwards the anterior segments and single pair of legs. 
The first and apparently most difficult part of the shedding of 
the skin is its detachment from the posterior segments of the 
body, and from the interior of the large intestine. To effect this 
the animal, which has been previously lying coiled up in a circular 
form, first straightens its whole body ; it then forcibly contracts and 
shortens itself, especially at the posterior part, and by this means be- 
comes greatly enlarged in bulk at its middle portion, but smaller at 
its extremities. During these efforts, which are some of the most 
powerful it is able to make, the skin becomes loosened from its 
posterior parts, and while still contracting its segments, the anal 
extremities, and with it the entire lining of the large intestine, be- 
come completely detached, and from these it gently withdraws 
itself within the old skin, in which the body is encased, as from the 
finger of a glove. This is precisely what takes place in the shed- 
ding of the skin in true insects. Having effected this part of its 
labour, all the posterior segments are again shortened ; the animal 
once more disposes itself in a circular form, and after repeated 
exertions, succeeds in bursting the tegument of the head in the part 
just described. As in the case of the true insects, the young Fels 
entirely empties its alimentary canal and ceases to eat for one or 
two days preceding each skin shedding. When examined imme- 
diately before the change there are no other symptoms of new legs 
than slight eievations of the skin, and this perhaps accounts for 
the length of time occupied in the change, the new legs requiring 
time for further development before the old skin is thrown off. 
Having cast its skin, and thus attained the fifth period of 
development, the young Yu/us has three ocelli on each side of 
the head, seven joints to the antenna, thirty-four legs, and twenty- 
one segments to its body. 
The ¥u/us changed its skin again on the sixty-third day, and 
entered its sixth period of development. It then had acquired 
twenty-seven segments to its body, which had greatly increased 
in size, and was of a brown tint. There were six distinct ocelli 
on each side of the head, and there were altogether fifty-eight legs. 
The Chilopoda, which have less numerous legs, appear to 
