1979] Carpenter — Permian Insects from Oklahoma 283 
The status of the family Doteridae Handlirsch is a more difficult 
problem. The original specimen of Doter minor Sellards (1907) 
consisted of two folded and twisted wings (both apparently fore 
wings) and part of the body, including the abdomen (Sellards, 1907, 
figure 13). When I examined the type in 1926 in Dr. Sellards’ labora¬ 
tory, I was surprised by its poor preservation. As Sellards correctly 
stated, the median caudal filament was not present and the clear 
preservation of the two cerci is almost conclusive evidence that the 
caudal filament was not present in the living insect. Its absence, in 
even vestigial form, would seem to eliminate the insect from the 
Ephemeroptera, since it is present in all the specimens of Palaeozoic 
and Mesozoic mayflies in which the abdomen and cerci are pre¬ 
served. It is also present, at least in reduced form, in virtually all 
existing mayflies. The venation of the type specimen of minor was 
so poorly preserved that I would have doubted that the specimen 
was actually the one described by Sellards, if the abdomen and cerci 
had not been formed as they were figured by him. The presence of 
well-developed cerci and the absence of the caudal filament are 
characteristic of a number of Elmo insects, such as the Astheno- 
hymenidae (Diaphanopterodea) and Protohymenidae (Megasecop- 
tera). The poorly preserved wings of minor did in fact have some 
resemblance to those of Asthenohymen Tillyard, as previously 
pointed out by Martynov (1930), and in my first account of that 
genus (1930) I considered dunbari, the type of Asthenohymen, to be 
a synonym of Doter minor. Since Tillyard did not accept that syn¬ 
onymy and since the type of Doter minor had been destroyed by 
then, 6 I suggested (1932) that Doter minor be regarded as an unrec¬ 
ognized species and that Asthenohymen dunbari be accepted as the 
valid name for the species described by Tillyard. That proposal has 
subsequently been generally followed, although Demoulin has con¬ 
tinued to recognize the family Doteridae as belonging to the Ephe¬ 
meroptera, regardless of the absence of the median caudal filament. 
It is highly probable that we may never find a specimen in the Elmo 
or Midco beds that fits Sellards’ description of minor. Some 20,000 
insects from those two beds have now been examined and none 
agree with his account of that insect. For this reason I believe that 
6 A few weeks after my return to Cambridge from the University of Texas in 1927, 
Professor Sellards informed me that during the process of renovating the building in 
which his laboratory was housed some workmen, thinking that the pieces of the Elmo 
limestone were fragments of the old walls, threw them out with the general debris. 
