THE WINGS OF INSECTS. 
J. H. COMSTOCK anp J. G. NEEDHAM. 
CHAPTER III. 
The Specialization of Wings by Reduction. 
I. INTRODUCTION. 
THE recognition of certain features of the venation of the 
wings of insects which occur in the more generalized forms of 
a large proportion of the orders of this class has enabled us to 
present a hypothetical type to which the wings of all orders 
may be referred. A detailed discussion of the features of this 
Fic. 5.— Hypothetical type. 
type has already been given; the figure representing it is 
repeated here (Fig. 5) in order that it may be easily compared 
with figures of actual wings. It represents the supposed 
arrangement of the trachez in a wing of the nymph of the 
primitive winged insect. By omitting the basal part, the figure 
will also serve to show the number and arrangement of the 
longitudinal wing-veins of the adult. 
It will be seen at a glance that this hypothetical type differs 
from the great majority of living insects in the possession of a 
larger number of wing-veins than is characteristic of them; it. 
also differs, and in a more striking degree, from most of the 
