1976] 
Carpenter & Richardson — Eucaenus ovalis 
241 
edge of the Palaeodictyoptera eliminates them from considera- 
tion as ancestral to any existing order, especially the orthopteroid 
groups, assignment of Eucaenus to the Protorthoptera seems 
most reasonable. Attempts (e.g., Sharov, 1968) to divide the 
Protorthoptera into orders or suborders (as the Paraplecoptera, 
Protoblattodea, and Protorthoptera, leading to the Plecoptera, 
Blattaria, and Orthoptera, respectively), seem to us to be very 
premature. The assumption that the orthopteroids of the Upper 
Carboniferous had already evolved into lines leading to these 
three orders is most improbable and certainly unjustified on the 
basis of available evidence; it is much more likely that the Paleo- 
zoic orthopteroids, especially those of the Upper Carboniferous, 
were evolving in many directions. Unfortunately, since most 
Paleozoic orthopteroids are known to us now chiefly by wings 
or wing-fragments, we are unable to discern what those directions 
were. When we know as much about the structure of most other 
Paleozoic families of the orthopteroids as we do of the Eucaenidae, 
we will be much better qualified to unravel their evolutionary 
lines. 
Eucaenus ovalis presents a good example of the necessity for 
a knowledge of body structures in evaluating the affinities of 
Paleozoic insects. On the basis of its wings, this insect was con- 
sidered by Scudder, Handlirsch and others to be a primitive roach. 
We now know that it was a specialized insect, with totally unex- 
pected adaptive modifications and with body structures that re- 
move it from any position leading to the roaches. It provides 
another illustration (Carpenter, 1971) of the diversity achieved 
by the insects of the Upper Carboniferous period. 
References 
Carpenter, F. M. 
1943. Carboniferous insects from the vicinity of Mazon Creek, Illinois. Il- 
linois State Museum Sci Papers 3:1-20. 
1966. The Lower Permian insects of Kansas, part 1 1. The Orders Protorthop- 
tera and Orthoptera. Psyche 73:46-88. 
1971. Adaptations among Paleozoic insects. Proc N Amer Paleontol Con- 
vent Chicago, 1969, part 1:1236-1251. 
Handlirsch, Anton 
1906a. Revision of American Paleozoic insects. Proc US Nat Mus 19:661-820. 
1906b. Die Fossilen Insekten. Wien. Pp. 1-1429 [Paleozoic section published 
in 1906; later parts in 1907 and 1908], 
