52 SUPPLEMENT ON 



The abdomen, the third region of the trunk in insects, has 

 been sufficiently described. It is sometimes articulated with 

 the metathorax, in the hinder region, by a broad surface. 

 Sometimes, on the contrary, the articulation is reduced to a 

 stalk, or pedicle, as in wasps, &c. The free extremity of the 

 abdomen is most generally pierced by the anus. The last 

 ring varies considerably in form : it is often conformed, so 

 as to favour the approximation of the sexes, to facilitate the 

 exclusion of the eggs, or their introduction into such sub- 

 stances as are proper to receive them. In this last instance, it 

 forms what Mr. Kirby has denominated the ovipositor. It 

 is frequently organized, so as to become a weapon offensive 

 or defensive. A variety of instruments, destined to peculiar 

 uses, often constitute a part of this region of the trunk. We 

 may add, that in each of the rings of the belly, the under, 

 upper, and lateral regions are distinguished, as to their form, 

 structure, spots, and movements, which furnish very good 

 characters, not only for genera, but even for species, and 

 difference of sex. 



The wings consist of pieces, articulated on the mesothorax 

 and metathorax, in the interior of which are placed very power- 

 ful muscles, by which all the variations in their movements are 

 produced. They are, in truth, light, but solid oars, formed 

 by membranes, and sustained by radii or strings, variously 

 disposed, to give them the necessary degree of suppleness, 

 resistance, and mobility. 



No insect is born truly winged, and some, which we term 

 apterous, never have wings. Some have but two, and then 

 they are named dipterous. Those with four wings are termed 

 tetrapterotis. But these distinctions have already been suffi- 

 ciently pointed out. 



Respecting the articulation, the composition, the shape, 

 the clothing, the colours, and divers other peculiarities of 

 the wings of insects, much might be written. But the neces- 



