REPORT OF THE STATE ENTOMOLOGIST I907 2ig 



It may be observed in any wing that costa, subcosta and radius 

 run closely parallel along the front margin of the wing and that 

 the subcosta lies in a deep groove between the other two, and is 

 usually strongly braced against them. Thus, both by approximation 

 of these strong veins and by the corrugation of the membrane, the 

 front of the wing is made rigid. The other posterior veins extend 

 wide apart diagonally across the outspread membrane of the wing 

 disk. 



The cross veins of a crane fly wing are rarely more numerous, 

 usually less numerous than are the longitudinal veins. A humeral 

 cross vein (h) strongly joins the costal and subcostal veins near 

 the base. The other cross veins of the wing that are considered 

 typical for the Tipulidae lie in the distal part of the wing and may 

 be conveniently designated by the names suggested by their posi- 

 tions, as follows: the radial cross vein (r), the radio-medial cross 

 vein (r-ni), the median cross vein (in), and the medio-cubital 

 cross vein (vi-cu), small letters being used as symbols to avoid 

 confusion. 



This system of venation is characteristic not only of all Tipulidae, 

 but also of all Diptera, and of a number of other orders of insects 

 as w^ell. In so far as the trunks of the principal veins are con- 

 cerned, it is characteristic of all winged insects. 



Toward the working out of the system of the venation of the 

 Diptera, systematic dipterologists have contributed surprisingly 

 little, and toward the correlation of it with that of other orders, 

 they have done nothing at all. Redtenbacher laid the foundations, 

 and Comstock built thereon, and by comparative study established 

 the system on a firm basis and published it in his Manual for the 

 Study of Insects. He once told me that it was in the study of the 

 venation of the Diptera that he first felt the solid ground of true 

 homologies beneath his feet. I have had hitherto no share in the 

 brilliant work that has been done on the venation of this order. 

 The chapters on Diptera, Hymenoptera and Lepidoptera of the 

 Wings of Insects were wholly the work of Professor Comstock. 

 After this work was done I joined him in a search for ontogenetic 

 confirmation of homologies already determined ; but in the order 

 Diptera, that search proved wholly fruitless. The proof of homo- 

 logies in dipterous venation rests on comparative anatomy alone. 



When Professor Comstock and I published jointly the JVings 

 of Insects, we endeavored to construct a wing that should be typical 

 for all the orders. Afterward, studying the venation of the 



