250 



THE WINGS OF PLECOPTERA 



The important features in which the assvuned plecopterous type of wing 

 differ from the hypothetical primitive type are the reduction of the radial 



^ Rz^i 



Fig. 247. — Wings of Gripopteryx tessellata (From Enderlein '05, but 

 with some changes in the labehng of veins). 



sector to a two-branched condition and a similar reduction of media to a 

 two-branched condition. The following examples illustrate these features 

 in each of the five families. 



The Gripopterygidae. — Figure 247 represents the venation of the wings 

 of Gripopteryx tessellata as shown by Enderlein ('05). In the fore wing of 



Cu2 Cu, 



Fig. 248. — Wings of Nemoura. 



this Species the radial sector and media are each clearly two-branched; 

 but the branches of the radial sector coalesce nearly to the apex of the wing. 



