1983] 
Burnham — Geraridae 
41 
SC 
Fig. 22. Progeneniumuni carhonis, drawing of fore wing based on holotype no. 
USNM 35580. 
Fig. 23. Progenentomum carhonis, photograph of fore wing, based on holotype 
no. USNM 35580. Length 30 mm, as preserved. 
be certain that this genus belongs in the Geraridae until a more 
nearly complete specimen is found, the fore wing is so similar to that 
of Gerarus that I do not hesitate to include it in the family. 1 cer- 
tainly can see no justification for the inclusion of Nacekomia in the 
Cacurgidae, where it was placed by Richardson (1956). The vena- 
tion of Nacekomia differs considerably from that of Cacurgus. In 
the latter, R is branched, RS simple, M is reduced, CUA simple, and 
CUP many branched. In the former, R is simple, RS branched, M 
has many branches, and CUA and CUP are simple. 
Geological range: Westphalian D. Occurrence: Mazon Creek, 
Illinois, U.S.A. Type species: Nacekomia rossae. 
