No. 376.] THE WINGS OF INSECTS. 257 
The fore wing of Hydropsyche (Fig. 28) with a slight madi- 
fication would serve as a typical insect wing. Excepting the 
coalescence of anal veins at the tip, the number and arrange- 
ment of the longitudinal veins in this wing correspond exactly 
with our hypothetical type; and only those cross-veins are 
present that may be considered typical on account of the fre- 
Fic. 28. — Wings of Hydropsyche. 
quency with which they occur in the more generalized members 
of different orders. 
In the hind wing the media is only three-branched and a 
tendency towards an increase in the number of anal veins is 
evident. This expansion of the anal area of the hind wings 
has been carried to a considerable extent in certain members 
of the order. 
Lack of space prevents a discussion of the various ways in 
which the primitive type of wing venation is modified within 
this order. But such a discussion is hardly necessary, for it is 
not difficult to understand the venation of the wings of these 
insects. 
ENTOMOLOGICAL LABORATORY, 
CORNELL UNIVERSITY, January, 1898. 
