I 



CHAPTER XX 

 THE WINGS OF THE STREPSIPTERA 



rst A 

 ^ 2d A 



Fig. 311. — Wing of Paraxenos 



eheri (From Pierce after 



Saunders). 



In this order the fore wings, which are termed elytra by some writers 

 and pseudo-halteres by others, are reduced to slender club-shaped append- 

 ages. The hind wings are large, compared 

 with the size of the tiny body, fan-shaped, 

 furnished with radiating wing-veins, and 

 folded longitudinally. 



The venation of the wings is degen- 

 erate. There is a variable number of radi- 

 ating veins, which in the most generalized 

 wings are eight in number. These are 

 supposed, by Pierce ('09), to be the eight 

 principal veins of the typical wing, the 

 costa, subcosta, radius, media, cubitus, 

 and the three anal veins, respectively, and 

 are so designated by him in his most 

 excellent monograph of the order. With 

 our lack of knowledge of the tracheation 

 of the wings, this conclusion can hardly be questioned. There are no cross- 

 veins. The veins are rarely forked ; but there are usually detached veins in 



the outer half of the wing. These extend longi- 

 tudinall}' in the area between the radius and the 

 media (Fig. 311). 



The detached veins are usually one or two in 

 number. Pierce makes no suggestion as to the 

 homology of these veins; but the arrangement 

 of the veins in the wing of Acroschismus huhhardi 

 (Fig. 312) leads me to believe that the first 

 detached vein is the radial sector; and the 

 second one, a branch of media. As this con- 

 clusion, however, is not incontrovertible, it will 

 probably be best, in descriptions of species, 

 merely to state the nimiber of detached veins between the radius and the 

 media, without attempting to determine their homologies. 



Fig. 312. — Wing of Acros- 

 chismus hubbardi (From 

 Pierce) . 



(301) 



