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CHAPTER V. 



Class IV. — Ptilota, or the Winged Insects of 

 Aristotle. 



This class of annulose animals is far more extensive than 

 the three already treated upon, and comprises those species 

 which are characterized by the possession, in the perfect state, 

 of six jointed legs and two antennae, and which are previously 

 subject to a series of transformations of a variable degree, by 

 means of which, in almost every species, organs of Hight are 

 developed, the latter cu-cumstance being, as already observed, 

 the grand character of the class. Hence it is that an inquiry 

 into the nature of these changes, and a consideration of the 

 pecuharities exhibited by insects during their progress to 

 matm-ity, will constitute the first step, and are, in fact, the 

 necessary commencement, of our inquiries into the nature of 

 insects. I propose, therefore, in the following pages, to en- 

 deavour to trace the insect through its various stages, first, 

 by a review of the general principles which regulate their 

 metamorphoses; and secondly, by an inquiry into the various 

 peculiarities exhibited by these animals in their passage to 

 the perfect state. To these will naturally succeed, thirdly, 

 a general view of the insect structure, especially as exhibited 

 in such perfect state, both externally and internally; fourthly, 

 a sketch of their physiological and instinctive properties; 

 termmating, fifthly, by a review of the classification of the 

 winged tribes of insects. 



