186 INTERNAL ANATOMY OF INSECTS. 



tagonist muscles 8 . In extracting the posterior leg of 

 Necrophorus Vespillo I observed more than a single 

 pair of muscles that had their attachment in the coxa ; 

 and probably many other variations in this respect exist. 



Little was known with respect to the most interesting 

 part of the muscular apparatus of insects, that by which 

 such wonderfully rapid and varied motions are imparted 

 to their organs of flight, till Chabrier undertook to 

 elucidate it ; which he has done in a manner that will 

 confer a lasting honour upon his name, as one of the 

 most able successors to Swammerdam and Lyonet in 

 their peculiar department. He has given a most admi- 

 rable account of the internal anatomy of the trunk of 

 insects in general, as far as it relates to their flight; 

 particularly of that of the cockchafer (Melolontha vul- 

 gar is), of one of the Libellulina (JEshna grandis\ and 

 of a humble-bee (Bombus) ; and I believe he has thus 

 illustrated insects of some of the other Orders, but his 

 memoirs on these I have not had an opportunity of con- 

 sulting. What I have to say on this subject, therefore, 

 will be principally derived from what he has communi- 

 cated with respect to the above insects. 



A considerable difference in the volume of the mus- 

 cles of the wings takes place in insects according to the 

 force of their flight. Where it is rapid and powerful, 

 the alitrunk is nearly filled by them, and the alimentary 

 canal is much attenuated ; but in those whose flight is 

 feeble, they occupy less space, and the alimentary canal 

 is proportionally enlarged b . In the Lepidoptera, Hy- 

 menoptera and Diptera, the principal muscles of both 



* Cuv. ubi supr. 459. b Chabr, Sur le Vol des Ins. c. i. 441. 



