FROM EMBRYOLOGICAL DATA. 



Far from inclining to such views, I am prepared to show that the very fact of 

 the complication of their jaws, and the multiplication of their parts, the greater 

 resemblance which those parts have to common legs, the immobility of the 

 prothorax, the hardness of their anterior wings, the frequent deficiency of the 

 lower wings, the similarity in structure between the jaws of the larva and those 

 of the perfect insect, are so many characters which assign to the Coleoptera a loAver 

 rank than that of the Lepidoptera. 



Indeed, if we institute a comparison between Coleoptera and Lepidoptera, we 

 are struck Avith the greater resemblance between the former, when perfect, and 

 the caterpillar, than between the beetle and the butterfly. It may be said, that the 

 beetle preserves the characters of the larvse of other insects, and assumes only 

 wings and more developed legs in addition, without reaching other successive meta- 

 morphoses, — those other changes through which the caterpillar passes before it is 

 transformed into the perfect imago. 



This being once granted, it must be acknowledged, in general, that chewing 

 insects should rank lower than sucking insects ; and we may perhaps find in the 

 complete metamorphoses of the higher Haustellata sufficient data to carry out this 

 view in determining the relative position to be assigned to all the orders of that class. 



Among the mandibulate insects, for instance, we have, besides Coleoptera, the Or- 

 thoptera, Neuroptera, and Hymenoptera. Now, the Neuroptera, though undergoing 

 metamorphoses as complete, in many respects, as the Coleoptera, have larvae whose 

 structure seems decidedly lower than that of the Coleoptera, for they are mostly 

 aquatic worms, provided not only with powerful jaws and all the complicated 

 chewing apparatus of mandibulate insects, but also with aquatic respiratory organs, 

 namely, true external gills similar to those of the aquatic worms. And the great 

 and complicated changes which they undergo, both in structure and form, lead to a 

 development which does not rank higher than that observed among Coleoptera. 

 Indeed, the soft wings of Neuroptera indicate, in my opinion, a character of low 

 development ; for their peculiar structure resembles more that of the wings of the 

 young butterfly, before passing into the condition of the pupa, than that of the ely- 

 tra. The wings of Coleoptera, again, resemble more closely the condition of the 

 wings in the pupa of the butterfly, at the period when the outer Aving is hard- 

 ened and soldered to the body, covering the lower wings, which remain soft. I 

 would, therefore, without hesitation, place Neuroptera as the lowest order among 

 Mandibulata. 



Next might come the Coleoptera, followed by the Orthoptera ; for Hymenoptera, 

 no doubt, rank highest in this division. To satisfy ourselves that this is the case, 

 we need only consider the structure of their jaws, the upper pair of which alone 

 preserve the character of chewing insects, while the lower are transformed into a 

 kind of proboscis very similar to that of Haustellata. Again, their larvae rank 

 higher than the larvae of either Neuroptera or Coleoptera. They are for the most 

 part larvae with aerial respiratory organs, and, in that respect, rank decidedly 

 above those of Neuroptera, and might be considered as of equal value with those 

 of Coleoptera. 



