366 
THE STUDY OF INSECTS . 
closely resemble those of the Hesperiidae. But the Giant 
Skippers exhibit a very peculiar specialization of wing struc¬ 
ture in the male sex. Here the two branches of vein VII of 
the fore wings separate from each other and from the cross¬ 
vein connecting them with vein V 3 , near the base of the 
wing (Fig. 446). In this sex this cross-vein, the branches of 
Fig. 446.—Wings of Megathymusyuccee^ male. 
vein VII, and vein IX are all very stout. The strengthening 
of these veins is evidently a specialization that increases the 
power of flight of this sex. For these stout veins must aid 
in depressing the hind wings during the downward stroke of 
the wings, as the hind wing is overlapped by that part of the 
fore wing traversed by these veins. The separation of the 
branches of vein VII from each other and from the cross¬ 
vein, so near the base of the wing, is directly correlated 
with the strengthening of these veins. In the course of 
the perfecting of the powers of flight in the male these 
