230 NEW YORK STATE MUSEUM 
more probable by reason of the fact that in the more generalized 
Ptychopteridae, Macrochile [pl. 4, fig. 1], Tanyderus [pl. 4, fig. 2] 
and Idioplasta [pl. 5; fig. 1], M® is strongly deflected toward the 
forward basal deflection of Cu’, and strongly attached thereto; 
and there is no reason for believing that this union, so important 
and constant a feature of the cord, once attained would again 
be lost in this series. 
This conclusion involves, however, a departure from the 
interpretation Professor Comstock has given for the branching 
of the median vein in Dixa and perhaps in other nematocera. 
Dixa is nearly enough allied to Ptychoptera so that I must hold 
the same interpretation for it. I would label the tips of its 
median vein as) M2 and) Me “and snot ass Wis andes Vice sb title 
hope some day to have opportunity for studying other nema- . 
tocera and establishing this matter by more abundant evidence. 
f in the diagram represents the condition of the median vein 
found in the fossil Rhabdinobrochus as figured by Scudder. It 
is fairly typical. And taken in connection with the apparent 
spur or rudiment of M® shown in figure 1 of plate 17 has tempted 
me to depart from the interpretation given by Professor Com- 
stock in another more important particular, to change the 
designation M® in all other crane flies to M*. But a spur in a 
single wing is altogether insufficient evidence for so sweeping 
a change. Furthermore, there is in certain Tipulinae! a furrow 
traversing cell 1st M? and running outward to the margin which 
is chitinized along its margins; and it is not impossible that 
this chitin line may have been the extra vein figured by Scudder, 
although that would not be characteristic of his marked keenness of 
observation. I believe that further knowledge of crane flies, 
both recent and fossil, will prove whether four branches of a 
median vein are ever present, and if both M® and M* really 
occur, in what order and manner they have disappeared. 
The ordinary course of reduction of Media is further shown 
in the figure at h, i, j, k, 1, none of which is hypothetical. In 
i, vein M® is about equally supported at.its base upon its de- 
flected base and the median cross vein, and when either support 
disappears, naturally it is the cross vein that disappears as a 
irule. But the exceptions are shown at m, n, o and p of the 
diagram, in which the deflection at the base disappears, leaving 
1Tt is shown particularly well in an undescribed Holorusia in my collec- 
tion from the Cameroons. 
