No. 378.] THE WINGS OF INSECTS. 415 
In the wings of these sawflies the anal furrow and the 
median furrow are both well marked, and are in the typical 
positions ; that is, the anal furrow is immediately in front of the 
first anal vein, and the median furrow in front of the media. 
The furrows are represented by dotted lines in the figures. 
In the anal area the three typical veins are preserved; but 
they coalesce to a considerable extent, both at the base and 
near the margin of the wing. 
In the basal part of the pre-anal area the stems of the princi- 
pal veins are as follows: the costa coincides with the costal 
margin of the wing (Fig. 38, C); the subcosta (Sc) is well 
preserved and is forked; back of the subcosta is a strong stem 
formed by the coalescence of the other three veins ; the cubitus 
(Cz) soon separates from this stem, extending in a curve 
towards the anal furrow; while the radius and the media 
coalesce for about half their length. In order to make these 
veins more distinct in the figure we have marked the free por- 
tion of the media with cross lines. 
When we pass from the consideration of the main stems to a 
study of the branches, we meet a much more complicated prob- 
lem, a problem which could not have been solved by a study 
of Hymenoptera alone. But a knowledge of the methods of 
specialization of the wings of Diptera gives a key to an under- 
standing of the wings of Hymenoptera. 
In the preceding article of this series we pointed out that in 
many Diptera there is a marked tendency for veins to coalesce 
from the margin of the wing towards the base. In the Hyme- 
noptera this tendency is much more marked and has been 
carried to a much greater extent, resulting in a very complicated 
arrangement of wing-veins, even in the most generalized mem- 
bers of the order. 
If the reader will examine the series of figures illustrating 
the coalescence of veins Cu2 and Zst A in the Diptera,! he will 
find it easy to understand what has taken place in the Hyme- 
noptera. In the Hymenoptera, however, both branches of the 
in Macroxyela but in Macroxyela vein Cuz is lost. See Comstock, Manual for 
the Study of Insects, p. 606, for figures of the wings of these two genera. 
1 American Naturalist, vol. xxxii, No. 377, pp- 338, 339- 
