1962] 
Carpenter — Permian Megasecopteron 
39 
menidae, the subcosta, and radius (Ri) are very close together and 
also to the anterior wing margin (text-figure 2). The costa is 
flattened and wide for its entire length. In the region of the 
pterostigma the costa widens even more and is somewhat thickened, 
but at the distal end of the pterostigma it disappears. The subcosta 
appears to be flattened and to be contiguous with the costa and is 
not readily distinguished from the latter. The radius (Ri) is con- 
tiguous with the subcosta (in the preserved part of the fossil) or 
with the costa beyond the end of the subcosta, except in the very distal 
part of the wing. Beyond the short but distinct pterostigmal veinlet 
the radius seems to fork, the more distal branch leading to the very 
apex of the wing. The cross-vein at the basal part of the pterostigma 
forms a heavy bar, which is especially thick at its costal end. 
The flattened costa, subcosta and even parts of Ri bear several 
irregular rows of setal bases or sockets (text-figure 2), as in some 
Text-figure 2. Photograph of part of wing of Actinohymen russelli, n. sp. 
(holotype), showing proximity of C, Sc and RI, and the origins of Rs and 
MA. Setal bases can be seen along the costa. 
Palaeodictyoptera, e. g. Dunbaria . It is curious that no setae are 
preserved, especially since they are often visible on the wings of 
Dunbaria. 
The wing markings are not unlike those of other species of Megase- 
coptera, especially the Carboniferous Aspidothorax triangularis 
Brongn. (Commentry, France). Eumartynovia raaschi Carp. 
(Permian, Oklahoma), though not at all closely related (z. e ., belong- 
ing to the Paramegasecoptera) , has almost identical markings. 
