1966] 
Carpenter — Protorthoptera and Orthoptera 
73 
Stereopterwn rotundum Carpenter 
Text-figures n, 12 
Stereopterum rotundum Carpenter, 1950, Proc. Amer. Acad. Arts Sci. 78: 
202 . 
Six additional specimens have been collected in the Elmo lime- 
stone since 1950, these bearing numbers 4959, 5253, 5254, 5258, 
5259, 5260; all were collected in the lower layer of the limestone 
(F.M.C.). The species has not yet been recorded from the upper 
layer. A survey of all of these fossils shows a greater variation in 
the venational pattern of the fore wing than has previously been 
realized. The subcosta and Ri remain fairly constant. Rs in sev- 
eral specimens (4959, 5880, 5885) has a deep fork; in another 
(5887) it has three branches instead of 2 and in a third (5879) it 
is unbranched. In the type specimen (4922) it has a shallow, distal 
fork. In a few specimens (5886, 5879, 5885) MAi is anastomosed 
for a short distance with Rs; in others, as well as the type, it is 
free from Rs. The weak condition of the basal part of CuA2, as 
seen in the type, is apparently unusual; in most specimens (e.g., 5887, 
5879) it arises distinctly from the stem of CuA; in one specimen 
(5886) it arises from CuA + M, i.e., before the separation of CuA 
from M. The pattern of cross veins is variable but essentially as 
shown in the type; beyond the end of Sc the oblique veinlets from 
Ri to the margin are somewhat closer together than elsewhere; this 
seems to be consistent in all specimens. The distinctive cluster of 
hairs on MA and MP near the middle of the wing can be seen in 
several specimens in addition to the type (e.g., 5879) ; few smaller 
setae are visible on some other veins but they do not form a definite 
patch. 
All of the fossils which show the base of the wing have a distinct 
lobe which resembles a heavily sclerotized fold of the costal area 
extending backwards of the base of Sc and R (see text-figure 11). 
Having noted this in several specimens, I attempted to chip away 
the very base of the type specimen, which turns out to have 
the lobe present also. This lobe was probably concerned with the 
fitting of the tegmen against the pronotum when the wings were 
in the resting position; a variety of sclerotized structures, which 
occur at the wing bases in many living orthopteroids, seem to have 
a similar function. 
Drawings of two specimens are included here (text-figures 10 and 
1 1 ) to show the extreme variation in some of the features mentioned. 
It should be noted that in one of the specimens (5886) there is no 
