ANNULOSA INSECTA. 



59 



The head bears a pair of jointed antenn93 (Lat antenna, 

 the yard-arm of a ship). These have-been considered by- 

 some naturalists 

 organs of smell; 

 by others, organs 

 of touch; others 

 again suppose 

 them to be or- 

 gans of hear- 

 ing. 



Each joint of , 

 the thorax bears 

 a pair of limbs. 

 There are from 

 six to nine joints 

 in each limb. 

 The foot or tarsus , 

 has several j oints. 

 It is followed 

 successively by 

 the " shank," 

 " thigh," and 

 " hip " joints. 

 The foot is 

 usually terminated by two hooks. 



There are generally two pairs of wings attached to the 

 dorsal surfaces of the second and third segments of the 

 thorax. The wings consi st of " a h ighly elastic m embrane, 

 stretched over a frame-work of strong tubes, as the silk 

 of an umbrella is expanded over its ribs." (Gosse.) The 

 front pair of wings in the beetles are hardened by chitine, 

 and form coverings for the protection of the membranous 

 pair. The extremity of the abdomen is furnished with 

 organs, which are sometimes used as weapons of offence 

 and defence, as the sting in bees and wasps ; and some- 

 times as "ovipositors," which serve for placing the eggs 

 in the required position. This ovipositor is a very com- 

 plex organ. It consists of a number of bristles enclosed 



FIG 21.- DIAGRAM or AN INSECT, 



"With the division of its body into head, thorax, and 



abdomen. 



