106 Professor Agassiz on the 



jaws are completely masticatory. But their position in re- 

 lation to Coleoptera and Neuroptera is difficult to determine. 

 They undergo no change after they have been hatched from 

 the egg, except that of assuming wings. They are born from 

 the egg with an aerial respiratory system ; indeed, in a con- 

 dition which is already higher than that of the larvae of Co- 

 leoptera, and decidedly higher than that of the Neuroptera. 

 We should, therefore, look to the changes which these ani- 

 mals undergo within the egg, to determine their true posi- 

 tion. But upon this point observations are still wanting. 

 At present I am inclined to place them above Coleoptera, as 

 we generally find that the degree of perfection which the 

 young assumes before it is hatched, corresponds, to a re- 

 markable extent, with the perfection of the animal in its 

 general structure. And if it were not for the peculiar struc- 

 ture of the jaws in Hymenoptera, I should not hesitate to 

 place Orthoptera highest among Mandibulata. Again, the 

 perfection of the wings of Hymenoptera leads so decidedly 

 to a parallelism between them and some of the moths, that 

 I cannot help thinking the best arrangement is the one men- 

 tioned above ; namely, Neuroptera lowest, next Coleoptera, 

 next Orthoptera, and Hymenoptera highest. The peculiar 

 piercers, with which so many Orthoptera are provided to lay 

 their eggs, remind us of similar apparatus in Hymenoptera, 

 which would go to substantiate the position now assigned to 

 these two orders of insects in close juxtaposition. 



Let us now consider the different orders belonging to the 

 division of the Haustellata, which contains only three groups, 

 the Hemiptera, Diptera, and Lepidoptera. The order in 

 which I have mentioned them above seems to me to be that 

 in which they should naturally be placed, according to their 

 structure and metamorphoses. If we can be guided by the 

 changes which the highest of the animals undergo, it will be 

 perceived that among Lepidoptera we have the true key for 

 their natural arrangement. The larvae of this last group are 

 hatched in a condition far superior to that of the larvae of any 

 other insects. Not only are they all provided with aerial 

 respiratory organs, but the different regions of their body 

 are already more fully marked out than in the larva? of any 



