178 



THE WINGS OF NEUROPTERA 



been suppressed in both wings, evidently by the spHtting back of vein R5 

 so that it arises from the main stem of the radial sector distinct from vein 

 R4. The splitting back of vein Rr, has progressed farther in the fore wing 

 than it has in the hind wing. 



The condition of the radial sector in Sisyra is much more generalized 

 than it is in the wings of the Hemerobiid^, for in Sisyra it is only four- 

 branched, no definitive accessory veins having been developed, although 

 marginal accessory veins are present. In fact the radial sector in these 

 wings differs from the typical fonn only in the fact that the dichotomy has 

 been suppressed. 



3d A 2d A ^^'^ 

 ■A 111,/ n. 



Fig. 172. — Wings of Sisyra flavicornis. 



Media is two-branched in both fore and hind wings, and in each case the 

 tips of the branches are forked. 



The beginning of the development of a secondary cubital fork is clearly 

 indicated, especially in the fore wing; but vein Cu2 is well preserved. 



Marginal dashes are present in the outer margin of the wing. 



The extended migration of the base of vein R5 of the fore wing towards 

 the base of the wing and the beginning of the formation of a secondary 

 cubital fork are specializations that are carried much farther in the Hemero- 

 biidas. 



(/l) THE WINGS OF THE SYMPHEROHIID.'E 



Even after the separation of the Sisyridas and the Dilaridffi from the 

 Hemerobiidse, as is now commonly done, there remains in this family 



