INTERNAL ANATOMY OF INSECTS. 179 



3. Abductors that draw an organ back, and Adductors 

 that draw li forwards. 4. Constrictors that contract an 

 opening, and Laxators that relax 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 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 LibelluLina, &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 . 



* VOL. III. p. 663, 670. See above p. 21. 

 > Chabrier Sur le Vol dqs Ins. c. i. 446. c VOL. III. p. 411. 

 d Ubisupr. 437,439. e PLATE XXII. FIG. 11, 12. c. 



Chabrier ubi supr. c. iii. /. xi. viii./. 9. S. D, z, k. c. i. 440 . 



N 2 



