356 ON THE ORDERS 



rise to more general scrutiny, from which we may con- 

 fidently expect the discovery of some new and highly 

 curious analogies. 



But before we can advance any further in our investi- 

 gation, it becomes necessary to take a general view of 

 Insects as they are grouped in the best modern works 

 on Entomology. 



MM. Cuvier and Latreille have the merit of first as- 

 sembling together into one group all the Annulosa which 

 do not breathe by means of branchiae or branchial pouches. 

 If from this assemblage we withdraw the Ametabola as 

 forming a distinct circular group, the remaining ani- 

 mals, although affording one of those abstract entomologi- 

 cal ideas which occur the most clearly and readily to the 

 mind, will defy the ablest attempts that may be made to 

 insulate them absolutely from the adjoining tribes by defi- 

 nite characters. If, for example, they should be designated 

 as Hexapods breathing by trachea?, we soon learn that 

 they possess stigmata and six feet in common Avith many 

 Ametabola and Arachnida. The composition of the mouth, 

 so beautifully developed by Savigny, is rather what they 

 all tend to have than what they really possess ; nay, the 

 component parts disappear in some Haustellata, and 

 are on the contrary all visible in some Ametabola. If 

 they be characterized as winged, hundreds of species which 

 truly belong to the group are apterous ; and so far are they 

 from being insulated from other animals, by undergoing 

 metamorphosis, that the Crustacea, Ametabola and Arach- 

 nida, all present instances of a difference of form between 

 the infant and adult state. The compound structure of 

 the eyes may perhaps afford the character most easy to be 

 seized, but even the organ of sight itself disappears in 



