No. 378.] THE WINGS OF INSECTS. 417 
coalesce at the tip, and that the migration of the united tips of 
these veins (marked Cz in the figure) towards the base of the 
wing has so modified the course of that part of vein M4 which 
is still free that this part of this vein extends towards the base 
of the wing. This change is very similar to the change in the 
course of vein Czz in the dipterous genus Rhamphomyia 
(Fig. 41).} 
A curious result of this change in the direction of the course 
of vein M4 is that the cell M4 has been closed and pressed 
back to the center of the wing (Fig. 39, M4), and now lies in 
front of the free portion of vein M4 instead of behind it. A 
somewhat similar modification of cell M, has been pointed out 
R, Rr43 
R 
“EDs 
Cu, +r25t A M,+Cu, è 
Fic. 42. — Wing of Eulonchus. 
in the Diptera; we repeat the figure of the wing of Eulonchus 
for comparison (Fig. 42). 
Let us now consider the courses of the branches of the 
radius. Here again we can gain help from a study of dipterous 
wings. Observe in Pantarbes (Fig. 40) the coalescence of the 
tips of veins R; and Mı:. In the Hymenoptera a similar 
coalescence of veins Rs and Mı has occurred; but it has pro- 
ceeded much farther, so that the free portion of vein Æ; in 
Pamphilius (Fig. 38, Rs) is remote from the end of the wing 
and has the appearance of a cross-vein. 
In the Hymenoptera vein R; has been followed in its migra- 
tion along vein M: by vein R4 which has now reached a stage 
in Pamphilius that is quite similar to that reached by vein X5 
in Pantarbes. But like vein R; it has the appearance ofa 
1At the time that the figures in Comstock’s Manual were prepared it was 
believed that the media was typically three-branched. For that reason the vein 
which we now regard as vein M, was believed to be a cross-vein. The interpreta- 
tion given above accords better with what we have since learned to be the typical 
form of the media 
