158 Mr. W. S. MacLeay un the Anatomy of the 



and been most original. He divides the thorax into three parts, protho- 

 rax, mesothurax and metathorax, and eacli of these into two external 

 parts f pectus and tergumj and one internal, the furca, and each of the 

 two external parts he divides again into analogous smaller parts, thus : 



Analysis of the Thorax. 



r 



THORAX 



or 



Truncus, Fab. 



r 



PROTHORAX 



Tergum 



Pectus 



Preescutum 



Scutum 



Scutellum 



Postscutellura 



Sternum 

 I Episterna 

 , * * * * 



( Epimera 

 Furca called Antefurca 



. MESOTHORAX . 



Praescutum 

 Scutum * 

 Scutellum 

 Postscutellum 

 Paraptera 

 Sternum 

 Episterna 

 Epimera 

 ^ Furca called Medifurca 

 Praescutum 



Tergum 



Pectus 



METATHORAX . 



Scutum 

 Scutellum 

 Postscutellum 

 Paraptera 

 Sternum 

 Episterna 

 Epimera 

 ^ Furca called Postfurca 



Tergum 



Pectus 



The above is a table of M. Audouin's theory. Now it being well 

 known that the developement of one part or segment exerts an inverse 

 influence on those which are contiguous, it follows that if the prothorax 

 be developed in the perfect insect, then the third segment or mesothorax 



* I have reason to suspect that this scutum of the mesothorax is resolvable 

 into three pieces, when at its maximum of developement, as in certain Hymen,' 

 optera, such as Chalcis, &c. I shall attempt to prove this afterwards. 



