THE WINGS OF NEUROPTERA 155 



sector does not indicate that this branch is composed of two coalesced 

 veins; it merely shows that the first branch of the sector is occasionally 

 split at the tip as are other veins in this region of the wing. 



This evidence is confirmed by a study of the wings of representatives of 

 nearly all of the genera of this family. Fortunately we are able to make 

 such a study, thanks to the labors of Dr. H.W. van derWeele. This author 

 in his Monographic Revision of the Megaloptera (Weele, 1910) has given 

 photographic illustrations of representatives of nearly all of the genera of 

 the Sialidse. 



The most important, for the purposes of the present discussion, of the 

 figures in this work is that of Corydalus priniitivus, a species found in the 

 Argentine Republic. The entire insect is figured, but I copy only the wings 

 (Fig. 149)- 



In this individual the dichotomy of the radial sector is not suppressed in 

 the right hind wing; but it is in the other three wings. That the first and 



Fig. 149. — Wings of Corydalus primitivus (After van dor Weele). 



second branches of the sector in the left hind wing and in both fore wings 

 correspond to the forked first branch in the right hind wing is shown by the 

 fact that counting the forked first branch of the right hind wing as two 

 branches, the sector is eight-branched in all wings. The splitting apart of 

 veins R4 and R5 in the right hind wing so that they arise separately, would 

 make the sector of this wing eight-branched like those of the other wings. 



I regard the structure of the right hind wing of this insect as an example 

 of atavism, similar to those found in the osmylids described above. 



Another remarkable insect figured by van der Weele, in the same 

 monograph, is Protohermes davidi from China. I copy a part of his figure 

 somewhat enlarged (Fig. 150), he figures the entire insect. 



Excepting the right hind wing of Corydalus primitivus discussed above, 

 the deepest forking of the first branch of the radial sector shown in the 

 figures given by van der Weele occiu's in this insect. That this forking is 

 due to a splitting of the tip of this vein is evident by a comparison of it 



