1976] 
Carpenter & Richardson — Eueaenus ova l is 
225 
on what we now recognize to be two abnormally preserved in- 
dividuals of the same genus. Our reasons for placing these fami- 
lies in synonymy and our understanding of the relationships of 
the Eucaenidae will be brought out in the following discussion. 
The family is known at present only from the ironstone concre- 
tions of the Francis Creek Shale of Grundy, Will, and Kankakee 
Counties, Illinois. 
Genus Eueaenus Scudder 
Eueaenus Scudder, 1885, p. 325; Handlirsch, 1906a, p. 710; 1906b, p. 165; 1911, 
p. 359. 
Teneopteron Carpenter, 1943, p. 359; Richardson, 1956, p. 46. 
Since only one genus is known in the family and only one spe- 
cies in the genus, generic characteristics can be stated only in 
general terms, especially in view of the variation in venation with- 
in some species of Protorthoptera (see Carpenter, 1966, p. 73). 
In all probability the extent of branching of RS and M will pro- 
vide the best source of generic differences in the wings and the 
forms of the prothorax and legs for the body differences. 
Type-species: Eueaenus ovalis Scudder. 
Eueaenus ovalis Scudder 
Eueaenus ovalis Scudder, 1885, p. 325, pi. 29, fig. 4; Handlirsch, 1906a, p. 710; 
1906b, p. 165, pi. 16, figs. 17, 18; 1911, p. 359, figs. 36-41; 1920, p. 162, fig. 112. 
Eueaenus mazonus Melander, 1903, p. 188-190, pi. 6, fig. 3, pi. 7, fig. 10; Hand- 
lirsch, 1906a, p. 710; 1906b, p. 165, pi. 16, fig. 19; not 1911, p. 32, fig. 32. 
Eueaenus attenuatus Melander, 1903, p. 190, pi. 6, fig. 4, pi. 7, fig. 1 1; Handlirsch, 
1906a, p. 710; 1906b, p. 165, pi. 16, figs. 20, 21. 
Eueaenus minor Handlirsch, 1911, p. 361-362, figs. 40, 41 . 
Teneopteron mirabile Carpenter, 1943, p. 17-20, fig. 5, pi. 5, fig. 4; Richardson, 
1956, p. 45-52, figs. 26-30. 
Fore wing (figure 1): length, 19-24 mm.; width, 7-8 mm; oval, 
with broadly rounded apex, rounded front margin and very 
slightly rounded hind margin; wing membrane coriaceous, ap- 
parently with a faint reticulation of ridges. Costal area broad, 
broadest at about mid-wing, somewhat narrowed basally; cos- 
tal veinlets oblique, numerous, probably more than 30; SC near- 
ly straight, slightly arched away from the costa, terminating on 
costa at about 4/5 of wing length; R1 parallel and close to SC, 
its termination not definitely known, but a few distal branches 
