470 
Psyche 
[December 
amount of variability in the hind wing shape and venation seems 
to be very great. Nevertheless, I do not consider it practical, at 
least at our present stage of knowledge, to separate into different 
families those genera in which the fore wings are much alike. In 
my opinion, the hind wings representing reduced structures may 
have been variable in form. The most modified hind wing of the 
Palaeodictyoptera occurs in Peromciptera Brongniart, the wing be- 
ing very short, broad and having an extremely reduced rs area. 
The hind wing of Valdectnia Teixeira is very short and broad also 
but the venation is similar to that of its fore wing (according to 
Teixeira, 1941, fig. 1). In both Eugereon and Dictyoptilus (fig. 
43) the hind wing is less shortened and narrow, approximately of 
the same width as the fore wing; the venation is modified more 
in the basal third, that is in the anal and cubital areas; the rs area 
is relatively well developed (Carpenter, 1964). So far, I consider 
these differences of generic level. 
Another remarkable morphological feature of Eugereonidae is 
the precostal area. This was mentioned for the first time by 
Lameere (1917, p. 160) in Dictyoptilus sepultus (Meunier) and 
later in the same species by Laurentiaux (1953, p. 423). As far 
as I am aware, the largest precostal area is present in both fore 
and hind wings of the families Eugereonidae and Calvertiellidae ; a 
narrower precostal area occurs in the related family Archaemegapti- 
lidae. It was probably present also in Protagrionidae. 
The precostal area of the families mentioned above is comparable 
with that of the Orthoptera, being formed by a series of short 
branches coming out anteriorly from a strong costa at its very 
base. It continues distally, forming a long membraneous precostal 
strip. However, a precostal strip, not broadened basally to form 
a precostal area, is common in Palaeodictyoptera, being especially 
pronounced in the Dictyoneuridae, Lycocercidae, Homoiopteridae 
and some Spilapteridae. In families with the precostal area well 
developed, the postcostal area is completely missing. 
The postcostal area, as far as I was able to observe it in the 
specimens, is present in all families of Palaeodictyoptera without 
a precostal area. Besides the Palaeodictyoptera, I was able to see 
it in those Megasecoptera which did not have the wings very 
narrowed basally. The postcostal area was first described by me 
in the Breyeriidae (1959) and in the Roechlingiidae (i960), under 
the inappropriate term “precostal area.” It is formed by a short 
vein, often branched, arising from the very base of the costa, and 
oriented obliquely, finally terminating again on the costa after a 
