INTERNAL ANATOMY OF INSECTS. 179 
3. Abductors that draw an organ bad; and Adductors 
that draw it forwards. 4. Constrictors that contract an 
opening, and Laxators that relax it. 5. Supinators that 
tarra 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 a , 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 Supinator and Pronator mus- 
cles; but some muscle of this kind must be in the Gryl- 
lotalpa, and in those that have a versatile head c . 
v. Attachment and Insertion. The attachment and 
insertion of the muscles in insects in general is to the in- 
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 d , which are connected with the base of the 
wings by ligaments. In the Dynastidce and other La- 
mellicorns, and the Libelhtlina, &c, a remarkable pro- 
vision is made for giving a vast increment of force to the 
muscles 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 e . 
1 Vol. III. p. 663, 670. See above p. 21. 
b Chabrier Sur le Vol des Ins. c. i. 446. c Vol. III. p. 411. 
d Ubisupr. 437, 439. « Plate XXII. Fig. 1 1, 12. c. 
( !habrier vbi supr. c. iii. /. xi. viii./. !). S. D. i, /,: c. i. 440—. 
N 2 
