PHYSIOLOGY OF INSECTS. 105 



mesothorax, is a narrow section, extending across 

 the insect from side to side between the hind 

 wings : this is the scutellum of the mesothorax 

 (mesothoracis scutellum). 



352. The next section is of similar shape, but 

 still narrower; this also extends from side to 

 side across the insect, and is the scutum of the 

 metathorax (metathoracis scutum). 



353. Now follows a large square section, into 

 the lower part of which is inserted the podeon, 

 or peduncle ; this is the scutum of the propo- 

 deon (propodeonis scutum). 



354. The sections developed are five in 

 number, being only one more than the number 

 of segments : it may be also observed, that the 

 three anterior sections are in a horizontal posi- 

 tion, the two posterior are in a vertical position. 



355. In beetles, butterflies, and many other 

 insects, these parts are not employed or men- 

 tioned in descriptions ; but in all insects with 

 transparent wings, they afford excellent characters 

 for distinguishing divisions. 



356. The telum, or last segment, frequently 

 bears appendages, the use of which appears 

 doubtful ; in some insects these are like bristles ; 

 in others, like forceps ; in others, like leaves, &c. 



