f)4 



THE THORAX OB TEUNK. 

 9 



The licinelytra are the wing covers of such insects as 

 we ordinarily denominate bugs; they are half horny and 

 half membranous. 



While these three :ire merely wing-covers, those deli- 

 cate membranous organs that serve exclusively the pur- 

 poses of flight, may alone properly be called wings. 

 We will for a moment turn our attention to the composi 

 tion or structure of these. 



The wings of insects, as we have intimated before, 

 consii^t of the breathing tubes, everted from the body, 

 and covered over with a thin membrane, which in some 

 kinds is plain, and in others decked with hairs, scales, 

 hooks, &G. 



Tile lirger of tlicse tubes are called the veins^ and 

 their branches the vei)dets^ or often they are termed the 

 lines of iieuration^ or nervures. 



