3i8 
Psyche 
[June 
ent on the wings, between the veins, and the main veins are covered 
with a series of setae. Costa is flattened and in larger wings some- 
times serrated ; it often carries a series of long setae, which are more 
pronounced basally. Subcosta consistently forms a conspicuous bend 
at the very base, probably related to the wing-folding process. Radius 
is always fused basally with the stem of the media. M, after diverging 
from R, immediately coalesces or joins either the stem of Cu and 
CuA, or directly CuA, for a short distance. MA and Rs are con- 
nected in North American Elmoidae by a cross vein. In Moravian 
Elmoidae the cross vein is present in only three species. In others, 
MA almost touches Rs or MA joins Rs at a point, or for a short 
distance, or both veins are anastomosed for a short distance. Cubitus 
runs closely to, or touches, R. The stem of Cu is always ribbon-like, 
deeply concave, broad and flattened. CuA and CuP originate near 
the point at which M diverges from the common R + M stem. Soon 
after diverging from M, CuA approaches CuP and is connected 
with it by an oblique cross vein. This feature seems to be a stable 
character of the family. Anal veins start from the posterior part of 
the sclerotized region, which is the thickened part of the wing 
membrane posteriorly from Cu and distally from the basal fold 
(fig. io,S). It undoubtedly served as a reinforcement of the wing 
base while folding the wings backwards. The basal plate is repre- 
sented either by the enlarged cubitoanal plate, or by the fusion of 
the median, cubital, and anal plates. It is partly homologous with 
the fused subcostoanal plate of the Palaeodictyoptera, the fused basal 
plate of the Ephemeroptera, and the radioanal plate of the Odonata. 
The basal fold runs between Sc and R + M, crosses R + M where 
it is flattened and weakly sclerotized, follows closely the distal 
margin of the fused basal plate, and crosses the anal part of the 
sclerotized region (fig. io,B). The axillary sclerite articulates with 
the proximal margin of the basal plate and with R. Its size and 
shape are not known. 
The family Elmoidae, as long as it was known only by North 
American species, was well separated from the related Upper Car- 
boniferous family Diaphanopteridae. The family Diaphanopteridae, 
represented by Diaphanoptera (France) and Philiasptilon (Soviet 
Union, Kuznetsk Basin), was characterized by the presence of the 
anastomosis between MA and Rs. In the Permian material from 
Moravia, however, this feature is highly variable. In Elmodiapha 
and Protodiapha (new genera), MA and Rs are connected only by 
a cross vein, as in the Elmoidae from Kansas and Oklahoma. In the 
other Moravian genera, MA and Rs are either touching each other 
