REPORT OF THE STATE ENTOMOLOGIST I9Q0O7 221 
principal veins, the same upward hitch of vein Cu! against media, 
and many of the cross veins occupy identical positions. Especially 
striking are the first two cross veins in the first fork of media, 
one delimiting, the other traversing cell 1st M*. The suggestion 
has been made before by others, and I think it very possible, that 
_ some Panorpidlike neuropteroid mutant got its center of gravity 
hitched forward, its hind wings reduced, and started the dipterous 
| line of evolution. | 
_ Homologies of cross veins. In my study of the venation of. 
_ the Odonata, I was quite unable to homologize any of their cross 
veins with those found in other orders of insects. And I do not 
believe that those indicated in the Comstock-Needham typical wing 
are necessarily homologous, even in those orders in which single 
¢ross veins occur at the points indicated for them in our type, for, 
primarily, cross veins are not formed about strong tracheae (they 
contain either late developing tracheal twigs or none at all), and 
they show, so far as I can see, none of the earmarks of homology. 
I conceive that such cross veins, as we may fairly regard as typical 
by reason of their frequent recurrence, are the survivors of the 
long elimination process just discussed. They are the cross veins 
that happened to stand in the positions most favorable for con- 
necting together longitudinal veins, ordinarily at the points where 
dichotomous branches came nearest together. If, as seems prob- 
able, there were originally many cross veins, and if the forks. of 
the principal veins varied somewhat in length and position in the 
ancestors of different groups, the same particular cross veins might 
not, probably would not, be preserved in every case. Those most 
useful would, naturally, survive the elimination process. Yet, with 
a similar form of wing and the same general primary disposition of 
branches of tracheae and veins, the process of elimination might 
leave a few strong cross veins in corresponding positions in very 
different insects, for it is always to be remembered that all wings 
have had to meet like conditions: the air is the same for all. The 
eross veins of the Comstock-Needham type are such. merely as 
recur in like position in a large proportion of winged insects, and 
whether strictly homologous or not, it is convenient to designate 
them by the simple method that Professor Comstock devised. It 1s 
in this sense that these designations are used in this paper. 
Some general features of the Tipulid wing 
The primitive ancestral crane fly doubtless possessed more veins 
in its wing than were necessary or advantageous, and these were 
