WINGS OF INSECTS, AND THEIR CLASSIFICATION. 45 



It has been found that he sound may be produced 

 artificially in dead specimens by rubbing the wings 

 together.* 



Fig. 20. 



A. Upper surface of right wing-case of Acrida brachelvtra. 



B. Under surface of left wing-case of do. 



C. File more highly magnified* 



For figures of Order II I. , Orthoptera, see Plate IV., 

 figs. 2, 3, 4, 5. 



From the insects whose encased and folded wings 

 have been described, we turn to the dragonfly, with 

 four large, strong, ever-expanded wings, which bear 

 the insect forward, backward, or from side to side with 

 equal ease, and with a swiftness far beyond that of almost 

 any pursuing enemy. 



These wings, with those of the smaller dragonflies, of 

 the delicate golden-eyed lace-fly, and others, are chiefly 

 characterized by their numerous nerves, which, inter- 

 secting their whole surface, form a kind of fine network 

 of small squarish meshes. The insects with these wings, 

 and some others in which the network is not so perfect, 

 belong to the order Neuroptera (vtvpoc, nerve, irrepov, 

 wing). The wings are always four in number, and 



* These figures, with some others nsed in this work, are taken from 

 Todd and Bowman's " Cyclopaedia of Anatomy and Physiology." 



