FROM EMBRYOLOGICAL DATA. 



But before they undergo their metamorphosis into pupae, before casting the last 

 skin of the caterpillar, the young Lepidoptera begin to form their wings, which 

 grow out of the second and third ring of the thorax in the shape of short, folded 

 bags, very similar indeed to the first rudiments of wings in Neuroptera. These 

 appendages rapidly enlarge, and when the caterpillar casts its skin, they have 

 already attained a considerable size. But, instead of remaining free, they are 

 soldered to the body of the pupa, the outer wings become hard, and form what have 

 generally been called the wing-covers, resembling then very much the wings of 

 Coleoptera. But the jaws have undergone greater changes. They are now trans- 

 formed into long appendages, similar to the articulated threads which constitute the 

 sucking apparatus of Hemiptera and some Diptera. The resemblance of the jaws 

 of Lepidoptera at this period to those of Hemiptera is so great, that we may truly 

 say, that the form of this apparatus in the pupa completely exemplifies the perma- 

 nent structure of the sucking apparatus in Hemiptera ; and the hardness of the 

 wing-covers reminds us at the same time of the hardness of the base of the upper 

 wings in the greater part of Hemiptera ; so that Hemiptera, in their perfect con- 

 dition, would correspond to the earliest condition of the pupae of Lepidoptera. 

 So the higher degree of locomotive power of these parts in Diptera would 

 remind us of the condition of the jaws in the Lepidoptera, at the moment the 

 perfect butterfly leaves its pupa, when the pieces of the mouth move indepen- 

 dently of each other, as is the case with the piercers of most Diptera, which 

 remain free, while in Lepidoptera they finally form the articulated proboscis. 

 This type of jaws of the Diptera, intermediate between those of Hemiptera and 

 the perfect Lepidoptera, would therefore assign to them also an intermediate posi- 

 tion in the system. 



Again, the peculiar development of the wings, the anterior of which become 

 perfect and membranous in Diptera, while the posterior ones remain rudimentary, 

 shows plainly that in the character of their wings, as well as in all other respects, 

 Lepidoptera rank highest among Haustellata, and therefore highest among all 

 insects. 



Whatever be now the value of these considerations, it must be obvious to all 

 those familiar with the subject, that such a classification differs radically from the 

 classifications founded upon metamorphosis simply. For here the system is founded, 

 not merely upon the fact of the insects undergoing changes to various extent, but 

 upon the nature of the changes themselves. This is a genetic classification, based 

 upon embryological changes, while the classification of the physico-philosophers 

 rests simply upon the circumstance of the insects undergoing metamorphoses or not, 

 without direct reference to the particular character of the successive changes. 

 They bring together Hemiptera and Orthoptera, because both undergo hardly any 

 changes after they have been hatched from the egg. But here it is shown that the 

 peculiarities which characterize Hemiptera correspond, to a certain degree, to the 

 transformations which Lepidoptera undergo, and that Hemiptera therefore appear, 

 upon embryological data, to belong to the same series, to which we must also refer 

 Diptera and Lepidoptera, but from which Orthoptera are excluded. Again, accord- 



