14 THE CLASSIFICATION OF INSECTS 



difference between the pupa and caterpillar, though the contrary would seem to be 

 the case. However, from what I have said above, it is plain that the Lepidopteron 

 arises from the larva with most of its perfect features, only developed in a less fin- 

 ished manner, while the changes which the animal undergoes during the pupa state 

 only consist, as it were, in the last perfecting of the final development already in- 

 troduced during the last period of the larval life. 



The skin of the pupa, having acquired its complete hardness, the appendages 

 having been soldered together, and now constituting a continuous case, in which 

 skin, legs, wings, antennae, and jaws are fused together, is gradually separated from 

 another more perfect envelope, which is to be the last covering of the last period of 

 life of the butterfly. All the ornamented appendages of this skin, its well-articu- 

 lated legs, its feathery wings, its articulated antennae, its facetted eyes, its elongated 

 movable maxillae, when perfect, remain separate from each other, movable upon 

 each other, and independent in their functions, and do not undergo again a fusion 

 similar to that by which the case of the pupa was formed and thickened. The only 

 connection which grows more intimate in the perfect animal than it was in the 

 pupa is that of the two maxillse, which henceforth are united along the middle 

 line, and between which a groove is left to form the curved proboscis. Gradually all 

 these parts are loosened from the inner surface of the pupa-case, they acquire their 

 peculiar coloring, and, the pupa-case bursting upon the back, the perfect insect 

 comes out in all its beauty. At first the wings, however, are shorter and narrower 

 than afterwards, when they have been expanded, stretched, and moved to prepare 

 for their final function. Sometimes, before being hatched, the process of these last 

 changes may be noticed through the skin of the pupa, which grows more trans- 

 parent in proportion as it is loosened from the surface of the insect within. A 

 row of variously colored dots in Danais Archippus, for instance, points out the posi- 

 tion of the wings, as well as their extent. In this butterfly the pupa-case is par- 

 ticularly transparent. The colors show most distinctly through the envelope thirty- 

 six to forty-eight hours before the perfect insect comes out, and, in general, a 

 change of color of the pupa is an indication of its advancing maturity. In some 

 degree the perfect wings are folded, but they actually grow, as well as expand, soon 

 after the butterfly has left its pupal envelope, and begins to lead that particular life 

 for which it has undergone these changes. It is now ready to pair, and, after 

 fecundation, to lay its eggs, by which the species is preserved, reproduced, and 

 perpetuated. 



III. SPECIAL CLASSIFICATION OF LEPIDOPTERA. 



IN the preceding pages we have described minutely the transformations of Euda- 

 mus Tityrus within the egg, up to its perfect development as an active butterfly. 

 We have shown that many points in the development of this animal have been 

 entirely overlooked, and that, in general, one stage of the metamorphoses of Lepi- 

 doptera has remained, if not entirely unknown to entomologists, at least unappre- 

 ciated in its bearings. The study of these metamorphoses in the new light in 



