METAMORPHOSES. 



53 



resemble the perfect insect in form, but are equally capable 

 with it of eating and moving. As these insects, however, 

 cast their skins at stated periods, and undergo changes, 

 though slight, in their external and internal conformation, 

 they are regarded also as being subject to metamorphoses. 

 These pupas may be subdivided into two classes : first, those 

 comprised, with some exceptions, under the Linnean Aptera, 

 which in almost every respect resemble the perfect insect, 

 and were called by Linne complete pupae ; and, secondly, those 

 of the Linnean order Hemiptera, which resemble the perfect 

 insect, except in having only the rudiments of wings, and to 

 which the name of semi-complete pupse was applied by Linne, 

 and that of semi-nymphs by some other authors. There is 

 still a fifth kind of pupae, which are not, as in other instances, 

 excluded from the skin of the larva, but remain concealed 

 under it, and were hence called by Linne coarctate pupae. 

 These, which are peculiar to flies and some other dipterous 

 genera, may be termed cased-nymphs. 



When, therefore, we employ the term pupa, we refer 

 indifferently to the third state of any insect, the particular 

 order being indicated by the context, or an explanatory epi- 

 thet. The terms chrysalis (dropping aurelia, which is 

 superfluous), nymph, semi-nymph, and cased-nymph, on the 

 other hand definitely pointing out the particular sort of pupa 

 meant : just as in Botany, the common term pericarp applies 

 to all seed-vessels, the several kinds being designated by the 

 names of capsule, silicle, &c. 



The envelope of cased-nymphs, which is formed of the skin 

 of the larva, considerably altered in form and texture, may be 

 conveniently called the puparium : but to the artificial cover- 

 ings of diflerent kinds, whether of silk, wood, or earth, &c. 

 which many insects of the other orders fabricate for themselves 

 previously to assuming the pupa state, and which have been 

 called by diflerent writers, pods, cods, husks, and beans, I shall 

 continue the more, definite French term cocon, anglicized into 

 cocoon. 



After remaining a shorter or longer period, some species 

 only a few hours, others months, others one or more years, in 

 the pupa state, the enclosed insect, now become mature in all 



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