1974] 
Kukctlova-Peck — Pteralia 
427 
Towards the base, the wing narrows markedly in the posterior 
part, while the anterior margin remains almost straight. Shortly 
before the base, the posterior margin curves posteriorly to form a 
prolonged axillary lobe parallel with the tergal margin. The serrated 
costa is attached at the very base to a long narrow plate on the lateral 
margin of the tergum. This plate is connected anteriorly with a 
prominent, darkly colored lobe. The subcosta is convexly bent near 
the base. Both costa and subcosta terminate on a triangular, highly 
convex basal plate, which is posteriorly connected to R + M and 
proximally to the small, convex axillary sclerite. This is associated 
with the tergal margin, the basal plate, the costa, the narrow plate 
on the tergum, and the anterior arm of the large elongated sclerite. 
The cubitus is concavely bent towards the very end of R shortly 
before the base, so that it creates the mirror image of the subcosta. 
The anal vein originates from a small anal plate, which is divided 
by a perpendicular suture into two small equal sections. The anal 
plate is directed obliquely and posteriorly against the posterior arm 
of a large, anteroposteriorly elongated sclerite. This closely contacts 
the tergum along almost its entire proximal margin. The elongated 
sclerite is highly convex posteriorly from the level of the end of the 
anal plate. In the anterior, flatter part, the axillary sclerite divides 
into two arms. The proximal arm is longer and slightly bent to at- 
tach to R + M and to the small axillary sclerite; the distal arm is 
shorter and directed to connect the curved end of the anal plate. 
This sclerite is markedly larger in the hind wing. 
The megasecopteran pteralia, as described above (figs. 10, 11), are 
so highly specialized that homology at our present level of knowledge 
is nearly impossible. The narrow plate laterally on tergum (np) 
and the elongate sclerite (Axe) as well seem to be compound struc- 
tures in which several elements might be incorporated. The small 
convex sclerite (Axe) is approximately in the position of iAx of 
Ephemeroptera ( sensu Tsui and Peters 1972; fig. 5). The little 
basal plate (ScPl) at the beginning of Sc is perhaps homologous to 
the subcostal basal plate of hypothetical primitive Paleoptera. The 
highly specialized character of megasecopteran pteralia shows that the 
construction of the wing attachment in Paleoptera was even more 
varied and diverse than it has been assumed. However, it should be 
taken into consideration that the pteralia of Protohymen may not be 
typical for the whole order Megasecoptera because of its relatively 
small size. In small insects, reduction and other modification of 
axillary sclerites sometimes occur. 
