CLASSIFICATION OF INSECTS. /9 



step. Systematically, the winged insects may be named 

 Ptilota, as proposed by Aristotle, and the Linnaean insects 

 will retain their name of Insecta, divisible into four classes, 

 namely, 



1. CRUSTACEA, 3. AMETABOLA, 



2. ARACHNIDA, 4. PTILOTA. 



The limits of the first two of these are acknowledged with 

 scarcely any variation by most modern writers, but the third 

 is a class, the limits of which have been by no means so de- 

 cided, Dr. Leach placing in it only the hexapod lice (Pedi- 

 culi), and the spring-tailed insects (Lepismce and Podurce) ; 

 whilst MacLeay has added thereto the Myriapoda, consist- 

 ing of the two orders Chilopoda (Scolopendras) and Chilo- 

 ynatha (lull), as well as certain vermes. 



For the purpose of making this work an introduction to 

 the knowledge of the whole of the Linnaean insects, I shall 

 in the first place give the characters, &c., of the first three 

 classes as concisely as possible, and subsequently detail more 

 at length the structural, physiological, and systematic charac- 

 ters of the true or winged class of insects. 



