42 
Psyche 
[Vol. 90 
Nacekomia rossae 
Figures 24 and 25 
Nacekomia rossae Richardson 1956:34. 
Description 
Fore wing: length 43 mm, but apex is missing; SC terminates in C, 
two-thirds distance from wing base; R parallel to SC, terminating at 
wing apex; RS two-branched, diverging from R at midpoint of 
wing; M with four well-developed branches; CUA strongly convex 
and fused at base with M, nature of CUP uncertain. 
Hind wing: unknown. 
Diagnosis 
It is impossible to designate specific characters when the genus is 
based on a single specimen, but in all probability the nature of RS 
(with only two branches) may be important. 
Geological range: Westphalian D. Occurrence: Mazon Creek, 
Illinois, U.S.A. 
Holotype: Nacekomia rossae FMNH PE 791. Specimen exam- 
ined. Obverse half. 
Genus Gerarulus 
Gerarulus Handlirsch 1911:318, 1919:30. 
Description 
Fore wing: SC parallel to C, terminating on it; R simple, RS 
branched; M with multiple branches, anastomosing briefly with RS; 
CUA simple, CUP elbows towards CUA. 
Hind wing: SC and R same as fore wing; RS pectinate; M simple; 
CUA and CUP independent from one another and parallel. 
sc 
Fig. 24. Nacekomia rossae, drawing of fore wing based on holotype no. FMNH 
PE 791. 
