248 THE AMERICAN NATURALIST. [VOC XXXII. 
In comparing the wings of nymphs, and especially of young 
nymphs, with those of the adult, it will be found that the 
growth of the basal part of the wing proceeds more rapidly at 
first than does that of the distal portion. This is shown by the 
fact that the branching of the branched trachez occurs much 
nearer the outer margin of the wing in the nymph than does 
the branching of the corresponding veins in the adult. 
The difference is not so great, however, as appears at first 
sight, for only a part of what is represented in Fig. 19 corre- 
sponds to the wing of the adult. The dotted line a—é indicates 
Fic. 20. — Cicada, base of hind wing. 
approximately the line along which the hinge of the wing of 
the adult is formed. In Fig. 15, the line a—d represents the 
corresponding part in the fore wing. 
By comparing Figs. 15 and 19 it will be observed that the 
forking of the radial trachea takes place much nearer the hinge 
line in the hind wing than it does in the fore wing. Upon this 
fact depends the most striking difference in the venation of the 
fore and hind wings of the adult. 
In the fore wing we found that subcosta and radius coalesce 
to a point near the nodal furrow. But in the hind wing it is 
only the anterior half of what is left of the radius after the loss 
of vein Rı that coalesces with the subcosta. The posterior half, 
