THE BIOLOGY OF THE CHRYSOPIDAE 132i 
ficially to be a branch of the media. This branch sends three smaller 
branches to the outer margin. The fourth branch basad is Cuz. There 
are usually only three anal tracheae, but in several instances a minute 
fourth was seen. There appears to be some variation in the second and 
third anals. These tracheae are small and difficult to study, but the 
essential features are fairly clear. The tracheation of the hind wing is 
almost identical with that of the fore wing. 
Application of tracheation to wings of adults 
It is evident that a correct interpretation of the venation of the 
adult Chrysopidae is impossible without a previous understanding of the 
pupal tracheation. The modifications shown are peculiar to the family, 
so far asis known. The first modification is seen at the tip of Sc. In 
the pupal wing, Sc ends at the inner border of the stigma. In the adult 
wing it appears to end beyond the stigma and near the tip of the wing. 
The stigmal cross-veinlets are the fused branches shown in the pupal 
wing from R,. There are few cross-veins between Sc and Rs, and these 
are at the extremities. This condition enables a kind of rotation to take 
place in flight, for both the cutting edge of the wing and the flexible 
hind border. The radial sectors in both pairs of wings of the adult are 
zigezageed, while in the pupal wings they are straight tracheae. 
Tt is at the end of the radial system and throughout the medial and 
cubital systems that the greatest coalescence occurs. The best way to 
name these branches is to find Cu., which corresponds to that branch in 
the pupal wing. It arises rather far basad from Cw,, and is branched 
in the front wing and unbranched in the hind wing. This vein having 
been found, the fourth branch forward is Cw, in both wings. Then, in 
regular sequence forward, the veins are M,, M3, M2, and M,. It will be 
observed that in both front and hind wings this arrangement generally 
holds, stopping with the fork of R;. In either wing, however, some 
variation occurs in this region. M, and M., and Mz and M,, may be 
joined at their bases and simulate the branched R;. M, may also be 
branched like RF;. 
The branches having been named, they can be traced to their origin. 
The ninth radial branch from Rs is the last to go straight to the margin 
without fusions. The tenth to the fourteenth branches, inclusive, so 
fuse at their bends as to form the pseudo-media and the pseudo-cubitus. 
M is fused with R at the base. In the front wing it divides into two 
branches which fuse quickly, forming the median loop and then sepa- 
rating. Apparently there may be considerable variation in the median 
loop. The lower branch, M; , 4, shifts along the upper branch and may 
