MODERN CLASSIFICATION 



OF 



INSECTS. 



I. Observations upon Insects in general. 



Insects, as proposed to be treated of in the following pages, may 

 be defined to be, Annulose Animals breathing by tracheae, having the 

 head distinct^ and provided in the adult state with six articulated legs 

 and antennae, subject also to a series of moultings previously to 

 attaining perfection, whereby wings are ordinarily developed. 



This definition, which comprises .the characters of the Ptilota 

 or winged insects, of Aristotle, does not, indeed, accord with that 



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required by the group of insects as extended by many recent authors ; 

 but the group thus defined is regarded^Mr. MacLeay (^Linn. Trans. 

 vol. xiv. p. 67.) as pre-eminently natural, and as constituting the 

 typical division of Annulose Animals ; and^ indeed, when we call to 

 mind the general characters of the classes of the Annulosa and other 

 invertebrated animals, it will appear evident, that the extraordinary 

 metamorphoses to which the Ptilota are subject, attended as they are 

 by the ulterior development of organs of flight, which exist in no 

 other group of invertebrates, ought to be regarded as especially 

 entitling these insects to be treated not only as a distinct, but as a 

 most natural, group *, and consequently as giving a superior degi'ee 



* It will, perhaps, be objected by some persons, that the existence of metamor- 

 phoses, as an exclusive character, is denied by the researches of Mr. Thompson, who 

 has asserted that the Crustacea undergo equally striking transformations. I have, 

 however, and I trust satisfactorily, disproved the statements of this author, in a Me- 

 moir published in the Philosophical Transaclions for 1835. It may also be said, that 

 the character employed by Mr. Newman to isolate the winged insects (tliat of their 

 incapability to reproduce their limbs) ought to have been employed. But this 

 character has also been long since refuted by Dr. Heineken in tlic Zoological Journal, 

 and by Dr. Burmeistcr in his Handbuch der Entomologie 



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