158 Mr. W.S. MacLeay on the Anatomy of the 
and been most original. He divides the thoraz into three parts, protho- 
rax, mesothurax and metathorax, and each of these into two external 
parts /pectus and tergum) and one internal, the furca, and each of the 
two external parts he divides again into analogous smaller parts, thus : 
ANALYSIS OF THE THORAX. 
ft Prescutum 
Scutum 
Scutellum 
Postscutellum 
PROTHORAX Sternum 
Episterna 
Peorus ¢,)e 4 « 
TERGUM 
Epimera 
Furca called Antefurca 
Prescutum 
Scutum * 
Scutellum 
THORAX Postscutellum 
or MESOTHORAX Paraptera 
Truncus, Fab. Popa: aa 
pisterna 
imera 
Furca called Medifurca 
Prescutum 
Scutum 
Scutellum 
Postscutellum 
METATHORAX Paraptera 
PEcTus uit 
pisterna 
Epimera 
Furca called Postfurca 
TERGUM 
TERGUM 
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 mesothoraw 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. 
