OUTLINES OF ENTOMOLOGY. 



457 



species, and are, to a large extent, the in- 

 struments of communication between in- 

 dividuals of the same kind, as among ants, 

 and no doubt aid the perception of in- 

 sects in many ways that are beyond our 

 comprehension. 



The sense of hearing in insects is not 

 considered to be as generally developed 

 as in the higher animals. Yet unques- 

 tionably many insects do hear, although 

 the special organs of this sense have been* 

 located in comparatively few species. 

 Such ears as have been discovered are 



Antennae of insects, adapted from not found On the head, but On the front 



"till t llOTfl 



i and 3, lamellate ant. of beetle. legs and at the base of the abdomen. 



2, capitate " " 



, pectinate These will be more particularly described 



5 and 6, Aliform 



7, bristle tipped ant. of fly. 



8, knobbed ant. of butterfly. 



9, feathered ant. of moth. 



in a succeeding chapter. 



CHAPTER IY. 



THE THOKAX AND ABDOMEN. 



The three segments immediately back of the head constitute the 

 Thorax or chest of an insect. This division of the body is very com- 

 pact and usually somewhat globular, or barrel-shaped. Each of the seg- 

 ments or joints composing it has received a special name ; the anterior 

 one — next the head — is termed the Frothorax ; the middle one, the 

 Mesothorax, and the third or posterior one the Metathorax. Each of 

 these divisions, though apparently entire, is in reality, as has already 

 been observed, made up of several irregularly shaped pieces, which are 

 connected in such a way as to afford free play to the strong muscles 

 within. 



The appendages of the thorax are the wings and legs. The wings 

 of insects are their most conspicuous members, upon which the beauty 

 and, in a great measure, the safety and enjoyment of most species de- 

 pend. 



In their adult and perfect state nearly all insects possess these 

 organs, the only exceptions being the members of a few small groups, 

 such as fleas, bed-bugs, lice, some of the ants, and the females of a few 

 moths and beetles. 



