184 THE WINGS OF NEUROPTERA 



The wings of Hemerohius hmnuli (Fig. 175) are very instructive in that 

 they show the beginning of the speciaHzation of the hemerobiid wings by 

 the development of accessory veins. In the hind wing, the radial sector 

 bears only the four primitive branches. In this enumeration the marginal 

 accessory veins are not counted. In the fore wing, there is a single definitive 

 accessory vein, vein Rqs- 



The wings of Megalomus mastiis (Fig. 178) will serve as an example of 

 the more specialized hemerobiid wings. In the hind wing, veins Ri and Rg 

 do not coalesce. As the radial sector is seven-branched, it is evident that 

 three accessory veins have been developed upon it. In the fore wing, there 

 is a complete coalescence of vein Ri and the stem of vein Rg, and a greater 

 nimber of radial accessory veins have been developed. 



The tips of all of the branches of radius are forked in both fore and hind 

 wings. This forking is especially marked in the case of vein R5, and has 

 resulted in the formation of a radial cuneate area of considerable size (Fig. 

 178, red). In the more generalized Hemerohius hmnuli, the tip of vein R5 

 is not markedly more forked than are the tips of other branches of the radial 

 sector (Fig. 175). 



Correlated with the prominent part played by tiie secondary cubital 

 fork in the hemerobiid group of families, there is frequently a tendency for 

 vein Cu2 to SLtvophj. In the hind wing of Megalomus mcestus (Fig. 178), 

 the base of vein Cuo is preserved, but the greater part of this vein is repre- 

 sented by a fold, indicated in the figure by a dotted line. In the hind wing 

 of Sympherobius (Fig. 173), only the base of vein Cu2 is preserved, there is 

 no vestige of the remaining portion. In this case the base of vein Cu2 is no 

 longer curved, as is usually the case, but a part of it is aligned with a cubito- 

 anal cross-vein. In the hind wing of Hemerohius humuli (Fig. 175) only 

 that part of the base of vein Cu2 that is aligned with the cubito-anal cross- 

 vein is preserved, so that there appears to be only a cross-vein in this 

 position. In Figure 176 the two parts of this apparent cross-vein are 

 lettered to indicate their homologies. 



(/) THE WINGS OF THE DILARID.^ 



This is a small family and one that is not well represented in collections. 

 There is only one species known from North America, and this is exceedingly 

 rare. I have before me wings of two species from Japan and figures of two 

 other species. The following statement is based on this limited amount of 

 material. 



Although the radius of the fore wings has from one to three sectors, the 

 increase in the number of sectors appears to be due to a splitting back of 

 one or two branches of vein R^ rather than to a coalescence of veins Ri and 

 Rs, as is the case in the Hemerobiidaj. But as we do not know what was 



