1930] Permian Insects of Kansas 363 
The Venation of the Protohymenoptera 
Having 1 considered the new fossils and the additional 
information which they give us on the wing structure of 
the Protohymenoptera, we are in a position to investigate 
the venation and to attempt to homologize the veins with 
those in other insects. Lameere, Martynov, and Tillyard 
have shown in recent years that the main longitudinal veins 
in an insect’s wing are either convex or concave, and that 
the convexity or concavity is always constant for that 
vein. Thus, the subcosta, when viewed from the upper 
surface of the wing, is always concave (-) , R1 always con- 
vex ( + ), Rs concave* etc. 2 In the more primitive insects, 
or at least in those with a fairly complete venational sys- 
tem, the convexities and concavities are strongly developed. 
Consequently, a well preserved fossil wing of such a type 
has the relief of the veins also preserved, and this is a 
great aid in identifying the veins and homologizing them 
with those in the wings of recent insects. Of course in 
the case of fossils, the obverse half presents the impression 
of the ventral surface of the wing, so that when we look 
at this half, we see the veins in the same relief as if we 
were viewing the original wing from the dorsal surface; 
that is, Sc is concave, R1 convex, etc. Conversely, the 
reverse half of the fossil is formed by the impression of 
the upper surface of the wing, so that we see the veins 
in the same relief as if we were looking at the wing itself 
from below; that is, Sc is concave, R1 convex, etc. Now 
the “key” to the identity of the two halves of a fossil wing 
is the subcosta; for it is the first vein in the wing below 
the anterior margin and it is present in nearly all insects. 
The subcosta is therefore easily recognized by virtue of its 
position, and when we find it concave in one-half of the 
fossil, we know we are dealing with the obverse piece, 
with the convexities and concavities of the veins just 
as on the dorsal surface of the wing itself. When we find 
the subcosta convex, we know we have the reverse half, 
with the relief of the veins in the negative position. 
2 Of course when we state that a vein is convex or concave, we 
imply that we are observing the veins from the upper side of the wing. 
