386 
Psyche 
[Vol. 94 
stem of M coalesced with stem of CUA basally; anal, cubital, and 
medial areas very broad. 
Discussion 
In the article cited above (1985), Kukalova-Peck described two 
specimens of nymphs, Lithoneura piecko and L. clagesi, from the 
Mazon Creek deposit, placing them in the order Ephemeroptera, 
family Syntonopteridae. Since the nymphs have a median caudal 
process, as well as the cerci, I agree that they are Ephemeroptera. 
Both of these nymphs had, in fact, been sent to me for study by Dr. 
Richardson many years ago. In a preliminary manuscript on them, I 
placed them in the Carboniferous genus Triplosoba Brongniart, 
family Triplosobidae, from Commentry, France. The type species 
of Triplosoba, pulchella Brongniart, is known by a single specimen, 
an imago having the three caudal appendages as well as an ephe- 
meropterous venation, and is the only Carboniferous insect that has 
been consistently placed in the order Ephemeroptera. Since the two 
Mazon Creek nymphs showed no significant venation, I discon- 
tinued working on them, with the hope that better preserved 
nymphs might be found. However, in my opinion the assignment of 
these nymphs to the Syntonopteridae is very questionable, since the 
latter family is not, with certainty, a member of the order Ephemer- 
optera. It is quite possible that the two nymphs belong to the family 
Triplosobidae. In this connection, it is worth noting that several 
genera of insects are found in both the Commentry shales and the 
Mazon Creek beds. One of these, Mischoptera, of the order Mega- 
secoptera, is represented by several imagoes in the Commentry 
deposit, although no nymphs of the genus have been found there; on 
the other hand, several specimens of nymphs, with the same vena- 
tion and body structure, have been found in the Mazon Creek con- 
cretions (Carpenter & Richardson, 1968). 
The precise affinities of the family Syntonopteridae are uncer- 
tain. Handlirsch (1911, 1919, 1922) placed it in the order Palaeodic- 
tyoptera, but of course he knew the family only by a small wing 
fragment, the holotype of S. schucherti. In 1938 and 1944, following 
my study of the specimens of Lithoneura, I suggested that the family 
may have been intermediate between the Palaeodictyoptera and the 
Ephemeroptera. A few years later, Edmunds and Travers (1954), 
linking the Syntonopteridae with both orders, proposed that the 
