574 THE AMERICAN NATURALIST.  [Vou. XXXIIL 
anal trachez respectively; but in most cases this division is 
not clearly indicated. 
In many of the saltatorial Orthoptera the anal area of the 
hind wings bears a striking resemblance to the wings of Ephem- 
erids, there being a regular alternation of convex and concave 
veins. In these cases the concave veins are evidently a later 
development than the convex veins. The increase in the num- 
ber of the branches of the anal trachez takes place at the cau- 
Fic. 74. Wi g r4 y h af Len h 
dal end of the series, and about each added trachea a convex 
vein is developed. It is only after the space between two of 
these convex veins becomes wide enough to admit of a fold in 
the wing that a concave vein is developed, and this development 
takes place in the same manner as in the Ephemerida. In some 
cases, as in the hind wings of Scudderia (Fig. 77), a tertiary set 
of anal veins is developed ; these extend only a short distance 
from the margin of the wing, and increase the resemblance of 
this area to an Ephemerid wing. 
