108 Professor Agassiz on the 



therefore assign to them also an intermediate position 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, shews plainly that, 

 in the character of their wings, as well as in all other re- 

 spects, 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 them- 

 selves. This is a generic classification, based upon embryo- 

 logical changes, while the classification of the physico-philo- 

 sophers 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 un- 

 dergo hardly any changes after they have been hatched from 

 the egg. But here it is shewn that the peculiarities which 

 characterise 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 Dip- 

 tera and Lepidoptera, but from which Orthoptera are ex- 

 cluded. Again, according to the views of the physico-philo- 

 sophers, the Coleoptera, Neuroptera, Hymenoptera, Diptera, 

 and Lepidoptera belong together, because they undergo ex- 

 tensive changes in their metamorphoses. But I have already 

 shewn that, however extensive these metamorphoses may be, 

 they do not rise in any of these orders beyond the develop- 

 ment which the Lepidoptera attain in their pupa condition ; 

 as in the pupa of Lepidoptera the jaws are already trans- 

 formed into a sucker-like proboscis, when wings and legs are 

 developed ; while Coleoptera, Orthoptera, and Hymenoptera 

 have arrived at their mature condition before the jaws have 

 reached a higher development of structure than that which 



