30 
Psyche 
[Vol. 90 
Diagnosis 
G.fischeri is remarkably similar to G. danielsi in many respects: 
prothorax, size, venation (compare fore and hind wings of each in 
figs. 6 and 14). The only obvious difference lies in the nature of 
CUA and CUP in the fore wing, \nfischeri CUA forks only once (in 
danielsi it has many small branches) and the anterior branch of 
CUP fuses with CUA for a distance of 9 mm. In danielsi the two are 
connected by a small cross vein. 
Remarks 
G. fischeri was first described by Brongniart for a series of 
orthopteroid insects recovered from the Commentry Coal Basin. 
The series is remarkable not only because it contains a large number 
of individuals, but because most of these individuals are exception- 
ally well preserved. Under these circumstances it is somewhat odd 
that affinities between the Commentry species and the Mazon Creek 
species went unrecognized for so long. Many of the Commentry 
specimens (especially IP 5, IP 7, and IP 23) have most of the body, 
including the prothorax, preserved and demonstrate the same 
arrangement of spine bases seen in the Mazon Creek material. 
Moreover, venation of the fore and hind wings in these specimens is 
unequivocally clear. Handlirsch might have recognized the similari- 
ties between Sthenaropoda and Gerarus had he examined the 
Commentry material himself, but this is debatable since the fore 
wing for Gerarus was unknown at the time. The similarities 
between G.fischeri and G. danielsi, given above in the diagnosis, are 
extraordinary. While separation of the two species on siich minor 
morphological differences might be subject to debate, I have chosen 
to recognize the two species as distinct from one another on geogra- 
phical and geological grounds. G. danielsi comes from Mazon 
Creek in North America (Westphalian in age) and G.fischeri from 
Commentry in France (Stephanian in age). 
Geological range: Stephanian. Occurrence: Commentry, 
France. 
Holotype: Gerarus fischeri. IP 5. Specimen examined. Obverse 
half only. This is probably the most spectacular of all the Commen- 
try gerarids and of great taxonomic significance because the wings 
are splayed apart and venation of both fore and hind wings is read- 
ily visible. The insect is preserved dorso-laterally and the three legs 
