Thorax in winged Insects. 161 



4. The epimera of the prothorax are not in general so much developed 

 as the episterna, but may be known by being often inferiorly situated, 

 and always in some connexion with the coxee. M. Audouin has ob- 

 served that they often articulate with the coxae by means of a small inter- 

 vening piece which he calls the trochantine. This piece is similar to 

 the trochanter, which terminates the coxa at its other end. 



I may here observe that when the stigmata of the prothorax, or any 

 other thoracic stigmata, are surrounded by a small horny piece, M. Au- 

 douin calls this the peritrema»* 



Op the Mesothorax. 



The mesothorax of an insect has, when at its maximum of develope- 

 ment, fotir pieces to the tergum (which is the mesothorax of Kirby) and 

 eight to the pectus (which is the medipectus of Kirby). 



The four superior or tergal pieces of the mesothorax are the prmscu- 

 tum, scutum, scutellum and postscutellum,f so named according to their 

 order from the head of the insect. 



1. The pi-cEscutum is the anterior, as its name denotes. It is the ^ro- 

 phragma of Kirby. J 



2. The scutum is a very important piece, often greatly developed, and, 

 according to M. Audouin, § always articulating with the bones of the 



or lateral margin of the prothorax, where this is terminated by the episternum 

 and epimeron. " La reunion de I'episternum, du paraptere et de Tepim^re 

 " constitue les Janes." The only names that are useful, however, are those 

 which denote the pieces of the thorax ; all others only burden the science. It 

 is just as clear, for instance, to talk of the side of the prothorax as of its 

 pleura or ora. 



* Very possibly the pnystega of Kirby is Audouin's peritrema of the meao- 

 thorax. 



f It is on this account that when a sternum is at its maximum of develope- 

 ment I name its four pieces, prtesternum, sternum, sternellum, and poststernum, 



X See Int. to Ent., Tab. 22, fig. 8. h'. 



§ I am inclined to differ with M. Audouin on this head, and think that the 

 scutum does not directly articulate with the wing, but by the intervention of 

 two lateral pieces, which I would call the parapsides. These are in general 

 soldered together with the scutum, but in many Hymenoptera, such as Chalcis, 

 &c., they are particularly distinct. 

 Vol. V. L 



