1983] 
Burnham — Geraridae 
15 
Fig. 4. Gerarus veiu.s, a. composite drawing of the fore wing, based on DGLS I 
and USNM 38136. b. composite drawing of the hind wing, based on DGLS I and 
USNM 38136. 
Hind wing: length 42-50 mm, width 11-12 mm; RS at least 
four-branched; M forked; CUA and CUP not known. 
Body: prothorax much smaller in this species than in G. danielsi. 
Width about 5 mm at its widest point, length 10-15 mm. Largest 
measurable spine 7 mm. Unfortunately, the arrangement and number 
of spines in this species is uncertain, but nine are expected in 
keeping with the genus. Head small, 4-5 mm in length. Coxae 
possibly enlarged; tibiae and femora long and slender. 
Diagnosis 
This species is distinguished from G. danielsi on the basis of its 
long and slender appearance, its diminutive prothorax and narrow 
wings. Unfortunately, the venation is not sufficiently preserved in 
any of the specimens assigned to this species to be useful as a diag- 
nostic character. Although body length is intermediate between that 
of G. danielsi and G. collaris, this species is clearly more slender 
than the other species in the genus. Compare fig. 5 with figs. 9 and 
13. 
Geological range: Westphalian D. Occurrence: Mazon 
Creek, Illinois, U.S.A. 
