Microscopical Essays; 177 



The trunk is fituated between the head and the abdomen ; 

 the legs and wings are inferted into it ; but in order to diftinguilh 

 the parts thereof more eafily, it is divided into the thorax, feu- 

 tellum, andflernum. 



The thorax is the upper part of the trunk; it is of various 

 Ihapes and proportions ; the fides and back of it are often armed 

 with points. 



The scutellum, or efcutcheon, is the pofterior part of the 

 thorax, and is generally of a triangular form ; though it adheres 

 to the thorax, yet it is eafily diftinguifhed from it, by its figure, 

 it's ufe, and often by an intervening future ; it appears defigned 

 to aflift in expanding the wings when the mfecl: is going to fly. 



The sternum is fituated on the inferior part of the thorax ; 

 it is pointed behind in fome fpecies, and bifid in others. 



The abdomen contains the ftomach, the interlines, the air 

 veffels, the ovary, Sec. it is affixed to the thorax, and in moft 

 infeas diftina from it, forming the pofterior part of the body, 

 being generally compofed of rings or fegments, by which the 

 infea can lengthen or fhorten it, or even move it in different 

 direaions. In fome fpecies it feems to be formed but of one 

 piece. The upper part of the abdomen is called the tergum, 

 the under part the venter ; the anus is the pofterior part of the 

 abdomen. 



The spiracula are fmall oblong oval holes or pores, that 

 are placed fmgly, one on each fide of every ring of the abdo- 



¥ men ; 



