WestwooW s Modern Classification of Insects. 6*29 



ticulated legs, and antenna, subject also to a series of moult- 

 in gs previously to attaining perfection, whereby wings are 

 ordinarily developed." This definition comprises the winged 

 insects of Aristotle ; and these our author regards as espe- 

 cially entitled to the rank of a distinct and perfectly natural 

 group, since their metamorphoses are attended by the ulte- 

 rior developement of organs of flight, which exist in no other 

 group of Invertebrata. 



We perceive that Mr. MacLeay has proposed in his recent- 

 ly-published memoir upon Dr. A. Smith's African Crustacea, 

 the theory that the Ptilota of Aristotle may be characterized 

 by their change of form occurring during their last two or 

 three stages of Ecdysis, while the metamorphosis of all the 

 other Annulosae only occurs during the first or second month 

 after leaving the egg : how this theory will bear investigation 

 has, however, yet to be proved. After determining the limits 

 of the class of insects, a sketch of their general structure fol- 

 lows, occupying thirteen pages, wherein are concisely describ- 

 ed the various organs in detail, and in which also are noticed the 

 chief researches of modern entomologists. The chapter re- 

 lative to the distribution of insects into orders, and the ar- 

 rangement of these orders, occupies twelve pages, in which 

 the systems of Swammerdam, Lamarck, Newman, Linnaeus, 

 De Geer, Fabricius, Latreille, MacLeay, Kirby and Spence, 

 and Stephens, are reviewed, and their peculiar merits discuss- 

 ed. Of these systems that of MacLeay appears to the author 

 to be the most natural, as it calls into action a greater num- 

 ber of relations than can be expressed by any other hitherto 

 proposed. With some slight modifications upon Mr. Mac 

 Leay's arrangement, the following is that adopted by Mr. 

 Westwood. 



Class of Hexapod Metamorphottc Insects. 



Sub-Class : Mouth with Jaws. Sub-Class : Mouth with a Sucker. 



(Dacnostomata, W.) (Anthiostomata, W.) 



Ord. Hymenoptera. Order Diptera. 



? Osculant Order Strepsisptera. ? Osculant Order Homaloptera. 



Order Coleoptera. ? Osculant Order Aphaniptera. 



Osculant Order Euplexoptera. ? 



Order Orthoptera. Order Heteroptera. 



? (Thrips P) ? 



Order Neuroptera. Order Homoptera. 



? ? 



Order Trichoptera. Order Lepidoptera. 



? ? 



Here the approach of the Trichoptera to the Hymenoptera, 

 and of the Lepidoptera to the Diptera, the direct passage 



3 q2 



