40 
Psyche 
[Vol. 90 
Geological range: Westphalian D. Occurrence: Mazon Creek, 
Illinois, U.S.A. Type species: Progenentomum carbonis. 
Progenentomum carbonis 
Figures 22 and 23 
Progenentomum carbonis Handlirsch 1906a:145, 1906b:70l, 1919:40. 
Description 
Fore wing: length 30 mm preserved (estimated as 50 mm), width 
15 mm; RS pectinate with four branches; distal branch of M elbows 
up to touch RS. A distinct cross vein connects branches two and 
three of M, and probably acted as a brace vein. 
Diagnosis 
This species differs from all others in the family in having a linear 
series of punctations between R and RS. These may or may not 
have been pigmented, but because this specimen is only an impres- 
sion, no organic material remains. 
Geological range: Westphalian D. Occurrence: Mazon Creek, 
Illinois, U.S.A. 
Holotype: USNM 35580. Specimen examined. Obverse half. 
Genus Nacekomia 
Nacekomia Richardson 1956:33. 
Description 
Fore wing: SC terminates in C two-thirds from wing base; R 
parallel to SC; RS two-branched; M four-branched; CUA and CUP 
simple. 
Hind wing: unknown. 
Diagnosis 
Nacekomia differs from Gerarus only in the nature of M, which is 
separate from RS, and not connected to it except by several very 
small cross veins. This, in my opinion, warrants separate generic 
status but not separate family status. 
Remarks 
This monotypic genus was originally included in the family 
Cacurgidae (order Protorthoptera), but is here transferred to the 
Geraridae on the basis of its fore wing venation. While one cannot 
