414 THE AMERICAN NATURALIST.  [VOL. XXXII. 
determine the homologies of the wing-veins by a comparative 
study of the wings of adults. We will, therefore, point out 
first what we believe to be the method of specialization of the 
Fic. 38. — The veins of a typical hymenopterous wing. 
wing-veins that has taken place in this order; and later we will 
discuss the nature of the changes that have taken place in the 
arrangement of the trachez. 
The method of specialization of wing-veins which has taken 
place in the Hymenoptera can be most easily seen by a study 
of the fore wings of certain sawflies. The most useful for 
this purpose that we have found belong to the genera Pam- 
philius and Macroxyela. If we are right in our interpretation 
of the wings of these insects, there is preserved in each genus 
all of the primitive wing-veins with a single exception. And, 
Fic. 39. — The cells of a typical hymenopterous wing. 
as in each of these- genera a different vein is lost, we are able 
to make a figure of a typical wing from a study of the two 
genera. Figs. 38 and 39 represent such a wing; in the former 
the veins are lettered; in the latter, the cells. 
1 Figs. 38 and 39 represent the venation of the fore wing of Pamphilius, except 
that vein 22, which is lacking in this genus, is added. This vein is well preserved 
