REPORT OF THE STATE ENTOMOLOGIST 1907 227 
“may become two branched. And, if the two branched sector 
at c in figure 14, and the one at e¢, exactly like it, be descended 
as indicated, they are less closely related to each other than 
‘either is to the three branched sector that stands before it in 
the diagram. Yet when the two types of branching are hover- 
ing about the parting of the ways, as they seem to be in the 
Cases just cited, we see that even differences of kind are in 
their beginnings merely differences of degree. 
This marked variability in a character that is elsewhere so 
constant and so important surely indicates that the crane flies 
are a very generalized group. In this, and in other characters 
as well, the main characters of the venation of the Diptera 
were not firmly fixed. The crane flies stand near the foot of 
the series, where venational experiments abound, and where the 
main trends of specialization are not everywhere fully estab- 
lished. 
A further reduction of the branches of the sector has occurred 
in many crane flies [see pl. 27, 28]. The two branched con- 
dition has been reached, apparently by the fusion from the 
base outward to the wing margin of R? and R®, as illustrated 
by Gonomyia [pl. 24, fig. 4, 5] and Cladolipes: also by the 
atrophy of vein R*, as indicated by Lipsothrix [pl. 20, fig. 5] 
and some Tipulinae. Apparently R? and R? have both atrophied 
Mie lLOxOnmainaee||piaezOueneoesilqee (ehere has) also voccunred! a 
noteworthy fusion from the tips backward of R*! and R* in the 
Cylindrotomini [pl. 15, fig. 4, 5, 6]. Certain other fusions involv- 
ing also the cross veins, will be considered after the cross veins 
have been discussed. 
The median vein is typically twice dichotomously branched, 
like the radial sector. Yet even more rarely does it show the 
full complement of branches. These were apparently fully de- 
veloped in the fossil crane fly Rhabdinobrochus [pl. 17, fig. 2] 
from Florissant, and all four are represented in a living unde- 
termined Tipuline shown in [pl. 17, fig. 1], although M®? is repre- 
sented only by a spur of a vein. Usually there are but three, 
er two branches: rarely there remains but one [as in Diotrepha, 
pl. 20, fig. 6]. The branches of the two main forks of media 
tend to be reduced by different methods; those of the anterior 
fork tend to fuse from the base to the wing margin; those of 
othe lower fork to disappear by atrophy. I have not found any 
evidence of atrophy in the anterior fork, nor of fusion in the 
posterior one. A number of the larger genera, like Limnophila, 
