LEPIDOPTERA. 321 
future butterfly. From the anterior extremity of the body are to be 
observed several small and narrow longitudinal compartments, ar- 
ranged like mummy bands, and extending over the breast: these are 
the coverings of the legs, spiral tongue, and antenne; the part from 
whence they seem to arise is the head, which is covered with a piece 
termed the cephalotheca. On the outside of these narrow bands are 
to be observed two broader scales, which, covering the wings, are 
termed pterotheca, arising from the opposite side to the breast, and 
which is the covering of the thorax, or cytotheca. This is followed by 
the abdomen case, gastrotheca. The covering of the spiral tongue 
is, in some species of Sphingidz, detached, and forms a snout, reach- 
ing to the base of the abdomen. 
When ready to assume the perfect state, the chrysalis skin bursts 
down the back and sides of the wing-covers, the anterior part separ- 
ating into several parts, and allowing the inclosed butterfly to make 
its escape; which it does with its wings moist and in an unexpanded 
state. ‘They soon, however, attain their full size ; the insect discharges 
a few drops of a thick fluid, and, in the case of the cocoon-making 
species, the insect pushes its way through the substance of the co- 
coon, sometimes splitting or dissolving the silk in a manner not satis- 
factorily ascertained. Some pupz have the segments furnished with 
rows of recurved spines, by which they are able to push themselves 
forward in the earth, or in the burrows the caterpillars had previously 
formed in wood, &e. 
The food of this order of insects consists almost exclusively of ve- 
getable matter, no part of the different kinds of plants being free from 
their attacks, although the leaves are the support of by far the great- 
est portion. I have had occasion to remark, in Loudon’s Arboretum 
Britannicum, that plants of the same natural family are especially 
liable to the attacks of allied species of Lepidoptera, the affinities of 
the one confirming those of the other; and M. Boisduval asserts that 
an imported plant will be attacked by insects having a strong natural 
relation with those which fed upon it in its native clime (Hist. Nat. 
Lep. p. 52.). Some species of caterpillars are indeed polyphagous, but 
the majority confine themselves strictly to a single species of plant, 
and their allies are attached to the same group of plants. Species of 
butterflies, allied to P. Machaon, feed upon Umbelliferze : those spe- 
cies of Papilio of North America, which are distinguished by their 
VOL. II. 4 
