1979 ] Carpenter — Permian Insects from Oklahoma 
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ADULTS 
As now known the protereismatid adults ranged from moderate 
to large in size. The wings were elongate-oval, without maculations; 
the hind wings were similar to the fore pair in form and venation, 
and were only slightly shorter; the costal margin was serrate and 
prominent setae were present on at least some of the veins; the costal 
brace was very well developed in both pairs of wings; MA, almost 
immediately after its origin, coalesced for a short distance with the 
basal part of RS; RS had three complete triads, and both MP and 
CUA had a single triad; cross veins were very numerous. The anten¬ 
nae, although short, were relatively longer than in existing mayflies; 
Figure 1 (above). Protereisma directum, n.sp. Photograph of holotype (fore 
wing), MCZ 5180a, Permian of Oklahoma. Length of wing, 26 mm. 
Figure 2 (below). Protereisma directum, n.sp. Drawing of fore wing (holotype). 
SC, subcosta; Rl, radius; RS, radial sector; MA, anterior media; MP, posterior 
media; CUA, anterior cubitus; CUP, posterior cubitus; cb, costal brace. The con¬ 
vexities and concavities of the veins are shown in figure I. 
