340 OF INSECTS IN GENERAL. 



by a poifer fituated under each wing, the bafe of which 

 is covered by a fmall fcale, and the extremity terminate^ 

 in a knob. 



The laft order comprehends in it all the apterous in- 

 fe£ls, or fuch as are entirely deftitute of wings in either 

 fex. 



In giving the hiftory of a clafs of animals fo ex- 

 tremely numerous as that of infe£is, it becomes abfo- 

 lutely ncceffary to group them in certain tribes, whofo 

 manners or external characters correfpond : Nothing 

 but this expedient can prevent endltfs confufion among 

 fuch multifarious forms, or afford any profpect of finidi- 

 ing a talk, that, at firft view, feems involved in fuch in- 

 extricable difficulty. All naturalifis who have treated 

 of this part of the animal kingdom, have accordingly 

 endeavoured to arrange them into orders and genera. 

 Sivammerdam and Ray feem to have founded their fyf- 

 tems en the different changes which thefe animals under- 

 go, and have formed them into four great divilions, a- 

 greeable to the dilTerent forms under which they appear: 

 Valifnieri has alfo diftributed them into four orders, ac- 

 cordirg to their habitation; arranging together in one 

 group, fuch as inhabit plants ; placing in another, thofe 

 that live in the water ; and in a third, fuch as conceal 

 themfelves under the earth or fand ; referving for his lad 

 divifion, thofe that inhabit the bodies of other animals *. 

 Both thofe fyUems are defe(ftive, in having too few divi- 

 fions of a clafs of animals fo extremely numerous ; the 

 laft, however, is liable to an imperfedion of another kind j 

 becaufe many infecls change their habitation, at the mo- 

 ment of their metamorphoiis. Some are aq^uatic, which, af- 



tev 



^ Vide Nouvelk idic d'lme clivificn generale des Infcdes. 



