1956] 
Adams — Chrysopidae 
73 
in genera such as Nothochrysa, this “vein” merges with 
the outer gradate series, turning up slightly near its end. 
As the straightening tendency reaches its culmination, 
e.g. in Chrysopa, Psm runs straight to the margin of 
the wing, and turns slightly downward near its end. 
Psc in genera such as Chrysopa may become straightened 
out basally, and is interrupted by Psm apically. 
The writer feels it most unlikely that, as suggested by 
Kimmins, Dictyochrysa could possibly have been ancestral 
to Triplochrysa. Admittedly, its venation reflects a most 
archaic condition. However, in the Planipennia, certain 
groups frequently become specialized by the multiplica- 
tion of the number of cross-veins or branches of the 
longitudinal veins. Examples of this which come readily 
to mind are the Psychopsidae, Drepanopteryx (Hemero- 
biidae), and the Palparinae (Myrmeleontidae) . These 
forms frequently retain a most archaic arrangement 
of veins, and hence furnish quite useful evidence for 
venational studies. The retention of these primitive char- 
acters, however, is not an indication that these forms are 
unspecialized and therefore eligible to be considered as 
ancestral to other groups. It is a result of a high degree 
of specialization by emphasis upon an amplification of the 
original system of venation, rather than specialization by 
reduction, or by modification of original pathways of veins 
by fusion. Dictyochrysa appears to constitute a case of 
this kind. There is no evidence that the network of hexa- 
gonal cells in the apical part of the wings is a primitive 
character; on the contrary, all the fossil forms have a 
relatively simple venation, with a normal number of cross- 
veins, and with oblong cells like those of modern represent- 
atives of the family. There is therefore no reason to assume 
that the simple venation of the fossil forms has become 
complex, as seen in Dictyochrysa, with subsequent reduc- 
tion to the condition of simplicity seen in Triplochrysa . 
It is the writer’s opinion that consideration of the 
venational trends discussed above — the progression basad 
of the subcostal cross-vein, the apicad migration of Rs, 
the formation of the first intra-median cell, and the re- 
lationship of the gradates with Psm and Psc — can furnish 
