METAMORPHOSES. 67 



at stated periods, and undergo changes, though slight, 

 in their external and internal conformation, they are re- 

 garded also as being subject to metamorphoses. These 

 pupae may be subdivided into two classes : first, those 

 comprised, with some exceptions, under the Linnean 

 Ajjtera, which in almost every respect resemble the per- 

 fect insect, and were called by Linne complete pupae; 

 and secondly, those of the Linnean order Uemiptera, 

 which resemble the perfect insect, except in having only 

 the rudiments of wings, and to which the name of seini- 

 complete pupae 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, ex- 

 cluded 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 dipte- 

 rous genera, may be termed cased-nymplis^ . 



When, therefore, we employ the term jpupa^ we may 

 refer indifferently to the third state of any insect, the 

 particular order being indicated by the context, or an 

 explanatory epithet. The terms chrysalis, (dropping au- 

 relia, 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 cascd-nymphs, which is formed of the 

 skin of the larva, considerably altered in form and tex- 

 ture, may be conveniently called the puparium^ : but to 



' Plate XVI. Fig. 4. 5. " Plate XVII. Fig. 1—4. 



' Plate XVII. Fig, 2. 



F 2 



