THE WINGS OF INSECTS. 
J. H. COMSTOCK anp J. G. NEEDHAM. 
CHAPTER III (Continued). 
IX. THE VENATION OF THE WINGS OF HYMENOPTERA. 
The Hymenoptera belong to the series of orders in which 
the direction of specialization of the wings results in a reduc- 
tion in the number of the wing-veins. This is true of the wing 
as a whole, the reduction taking place in the anal area of the 
wing as well as in the pre-anal area. We have found no repre- 
sentative of the order in which all of the veins have been 
preserved ; and in the more specialized forms nearly all of 
the veins have disappeared. 
A study of all of the families of the order shows that the most 
generalized of living forms, so far, at least, as concerns the 
structure of the wings, are to be found in the families Siricidze 
and Tenthredinidze. In these we find a close approximation 
in the number of wing-veins to the hypothetical type. But 
even here the courses of the branches of the forked veins have 
been greatly modified. These changes have been so great that 
the determination of the homologies of the wing-veins in this 
order was one of the most difficult problems of the kind that 
arose in the course of the study of the wings of insects. 
This determination was made by the, senior writer from an 
€xamination of the wings of adults before our present method 
of ontogenetic study was devised.!_ In the course of the present 
investigation we have endeavored to test the accuracy of his 
conclusions by a study of the tracheation of the wings of 
hymenopterous pupæ. We have found, however, that although 
the wings of the more generalized forms are abundantly supplied 
with trachez, the courses of these tracheze have not been modi- 
fied in the same way as have the courses of the veins with 
which they correspond. For this reason we are still forced to 
1Comstock, Manual for the Study of Insects, pp. 603-607. 
