THE THORAX OK TilUJSTK. 



47 



CHAPTER VIL 



STYLOPS ATEREIMA. 



THE THORAX OR TRUNK. 



The thorax of the insect is the centre of motion, and 

 the main support and prop of the two other primary- 

 sections of the body, of which the head'Y^ the principal 

 seat of the organs of sensation, and the abdomen of di- 

 gestion, respiration and generation. 



It may be observed in relation to its substance^ general 

 form^ proportions, composition or jyarts, internal anat- 

 omy and members, and of these it will be spoken of here 

 only in relation to its composition or parts, and mem- 

 bers, i.e. wings and legs — its internal anatomy furnishing 

 a subject for distinct consideration, and its substance, 

 form and proportions are points that may be readily ob- 

 served by the student without any assistance. 



Composition or Parts. — The thorax is composed of 



