THE CRANE-FLIES oF NEw YorK—Part [ 865 
the base of the sector and finally being lost by atrophy or by fusion 
with R,; the exotic genus Ceratocheilus shows this intermediate condi- 
tion very remarkably, and indicates clearly the manner in which this 
extreme reduction of the sector in Toxorhina was brought about. 
The media (M, fig. 128, a), or medial vein, like the radial sector, in the 
hypothetical type of an insect wing is twice dichotomously forked, the 
closed cell, 1st M2, lying in the first fork. There are no known crane- 
flies that show this condition except the’ doubtful fossil genus Rhabdino- 
brochus, which is apparently based on an abnormal and imperfectly pre- 
served specimen, and occasionally freak specimens of Tipula which indicate 
this condition by spurs of varying length. These specimens show that 
the single posterior branch of the media which persists is M., the spur 
_always lying on the cephalic side and representing the atrophied M3. 
Comstock (1918:349, fig. 360) has interpreted the venation of Protoplasa 
fitchazi as showing all four branches of media, M4 being fused with Cu, dis- 
tally. That this is not the true interpretation is indicated by a study of 
the other species of Protoplasa. The vein in cell M3; which Comstock 
interprets as being the downward deflection of M, is a supernumerary 
cross-vein. In this remarkable family of flies, such cross-veins are very 
often found in different cells of the wings. That the presence of a vein 
in cell M3 is a specific character only is shown by the fact that it is lacking 
in the related Protoplasa vipio O.S. My, and M2, comprising the anterior 
fork of the vein, are either separate or fused at the wing margin; such 
genera as Limnophila (Plates XXX VIII-XL) show a perfect succession, 
from deep forks as in the exotic Limnophila eprphragmoides (Alexander, 
1913 b:543), thru less deep forks as in L. montana (Plate XL, 148), to 
L. brevifurca (Plate XX XVIII, 125), which has a very shallow fork that 
is sometimes fused clear to the wing margin, and further to the numer- 
ous species of the genus (Plate XL, 150-157) in which there is a 
permanent and constant fusion between these veins extending entirely 
to the wing margin and obliterating the cell M;. Im all except the 
most generalized species, including nearly all of the Limnobiinae, the 
medial-cubital cross-vein (m-cw) is obliterated by the fusion of Mz+4,4 with 
the upward deflection of Cu; this fusion may be short or long, and is 
discussed in connection with the cubitus. After breaking away from 
the cubitus, M3; generally runs free to the wing margin, but in some 
cases (as in Styringomyia and Phalacrocera, Plate XXX, 8 and 9) it 
