THE WINGS OF HEMEROBIIDM 



183 



the base of the wing, so as to obHterate the small cell between them and also 

 towards the apex of the wing for a certain distance would produce the condi- 

 tion that exists in the fore wing. 



A stage intermediate between that of the radial sector in the hind wing 

 oiHemerobius humiili and that of the fore wing of the same species, where the 

 coalescence of the stem of the radial sector and vein Ri is carried so far that 



Fig. 178. — Wings of Megalonius via'stiis. 



both veins R5 and R4 arise separately, is presented by a hemerobiid pupal 

 wing figured by Comstock and Needham (Fig. 177). Here only trachea R5 

 arises separately. 



In the more specialized members of the Hemerobiidas a large number of 

 definitive accessory veins have been developed upon the radial sector or 

 upon the coalesced veins Ri and Rsi this development of accessor}'- veins 

 has progressed much farther in the fore wings than in the hind wings. The 

 two pairs of wings differ also in the fact that in the hind wings the stem of 

 the radial sector is not suppressed. 



