172 INTERNAL ANATOMY OF INSECTS. 
3, Abductors that’ draw an organ back, and Adductors 
that draw it forwards. 4. Constrictors that contract an 
opening, and Lazators that relaz it. 5. Supinators that 
turn the underside of an organ upwards, and Pronators 
that return it to its natural situation. Some of these 
muscles in insects, like some of their articulations and 
_ their spinal chord*, seem to exercise a double function,— 
thus the levators and depressors of the wings are con- 
strictors and laxators of the trunk». At first it may 
seem that insects, not having the power of turning up 
the hand, cannot have the Supznator and Pronator mus- 
cles; but some muscle of this kind must be in the Gryl- 
lotalpa, and in those that have a versatile head*. 
y. Attachment and Insertion. The attachment and in- 
sertion of the muscles in insects in general is to the zn- 
terior of the crust, or to some of its internal processes 
as a fulcrum, and to the organ to be moved. In some. 
cases, however, the muscles act upon the organ by the 
intervention of other bodies. Thus, those that move the 
wings are often attached to little bones, as Chabrier calls 
them’, which are connected with the base of the wings 
by ligaments. In the Dynastide and other Lameili- 
corns, and the Libellulina, &c., a remereable provision 
is made for giving a vast increment of force to the mus- 
cles of the wings, by means of caps or cupules sur- 
mounted by a tendon, which receive their extremity ; the. 
tendon terminating in a fine point attached to the wing, 
and thus more muscles are brought to bear upon it® 
* Vox. IH. p. 664, 671. See above, p. 21. 
b Chabrier Sur le Vol des Ins. c. i, 446. * Vor. IIT. p. 412 
d Ubi supr. 437, 439. © Pirate XXII. Fie. 11, 12. ¢. 
Chabrier udi supr. c. iii. t. x1. vill. f. 9. S. D. i, kc. i. 440— 
