220 INSECTS. 



merits, and separated from the second by a very marked articula- 

 tion ; in others it is extremely short, and has the appearance of 

 a collar, while the two following segments, of greater size, and 

 internally united, form a rounded mass distinct from the abdo- 

 men. In both these cases the large naked portion receives 

 the name of thorax. 



The insects of the first three orders have but one species of 

 locomotive organs, and only proper for walking ; others have 

 also wings to the number of four ; and the posterior extremity 

 of the thorax is furnished, in those which have only two wings, 

 with two appendages, one on each side, termed poisers or balan- 

 cers, (halter es,) and often other appendages in the form of spoon- 

 like scales (squamulce) or winglets. 



The icings (alee) are membranous, elastic, generally transpa- 

 rent, and attached to the upper sides of the thorax. The ribs 

 or nerves, more or less numerous, which run through them, form 

 sometimes a net-work, sometimes anastomosing veins. In wasps 

 and bees, thesa wings, four in number, are naked and transpa- 

 rent ; in butterflies they are covered with minute scales, re- 

 sembling fine powder, and embellished with the liveliest co- 

 lours. These scales are imbricated, each has a peduncle, and 

 they form in conjunction a kind of Mosaic work, exhibiting 

 the characteristic figures and colourings of this part. In the 

 large class of the Coleoptera, in place of upper or anterior 

 wings, two large scales or plates, opaque, more or less thick 

 and solid, and which open and shut longitudinally, form for the 

 membranous wings coverings, which are called wing-cases or 

 elytra (involucra.) In the greater part of the Orthoptera these 

 wing-cases or upper wings become less thick and solid, and are 

 furnished with ribs ; in the Hemiptera they are in a great part 

 membranous ; and the gradual transition from crustaceous co- 

 verings to membranous and transparent organs indicate that the 

 wing-cases in the Coleoptera, though scarcely contributing to 

 the action of flight, are modified wings. 



The form and disposition of the wings is much varied. 

 In some they are straight and extended, or folded longitudi- 

 nally like a fan, in repose ; in others, they are folded trans- 

 versely, as in the Coleoptera ; and in others again, as the ear- 

 wig, while one portion of the wings is folded transversely, the 

 other takes the fan-like fold. The wings vary also in their 



