INTERNAL ANATOMY OF INSECTS. 183 
posterior coxse?, their anterior attachment to the solid 
parts to be moved. In the Cockchafer and the Dynas- 
tide, but not in Geotrupes, on each side of the cavity of 
the metathorax under the base of the wing is a large and 
small cupule, which from their /ateral situation one would 
think must receive the levator muscles—apparently un- 
noticed by M. Chabrier; but as there is a pair of these 
cupules on each side, there must have been also a pair 
of muscles attached to them, which does not agree with 
his statement>. In the Hymenoptera and Diptera the 
anterior attachment of the depressors is to the back of the 
alitrunk and to the prophragm, and the levators to the 
breast, and the sides of the back of the trunk‘. In the 
Libellulina the depressors and levators that terminate, 
by a tendon surmounting a cupule, in the base of the 
wings, have their posterior attachment in the breast. 
These cylindrical muscles with their cupule and tendon 
look like so many syringes‘. 
Having thus described to you the powerful muscular 
apparatus by which, either mediately or immediately, the 
wings of insects are moved, it will not be out of place if 
I add a few words upon their flight itself. ‘The great 
object in this is to generate a centrifugal force which 
may counteract the weight of the body. Its wings are 
the external organs by which the insect as it were takes 
hold of the air when they fall, and is impelled by it when 
they rise; its head makes way for it; its abdomen, as a 
rudder, steers it; and by alternately increasing and dimi- 
2 [bid. 333. > Ibid. 332. Prats XXII. Fic. 11, 12.c. A 
cupuliform process is also observable at the side of the metaphragm. 
Ibid. Fre. 10. a. ¢ Chabr. oid. c. iv. t. xi— 4. f. 14. 
8 Ibid. c. i. 445. xi— 8. f. 8, 9. 
