864 CHARLES PauL ALEXANDER 
relatively deep, but it gradually becomes shallower until in such forms 
as G. sulphurella (Plate XXXVI, 91) it is very small and only a step 
removed from the condition obtaining in the subgenus Leiponeura. The 
venation in the genus Cladolipes, of the tribe Hexatomini, is similar. 
The genus Paratropeza of the tribe Antochini is the only member of that 
tribe with R, and R; separate at the wing margin, and in keys to the 
Tipulidae this genus runs down to the Eriopterini; the species are all 
exotic and are evidently the most generalized members of this aberrant 
tribe. In a few species of Gonomyia related to G. blanda (Plate 
XXXVI, 89 and 90), Re is very close to R; at the wing margin, in some 
cases being actually fused with it; this is likewise the condition in the 
Neotropical group Psaronius, where the fusion is most emphatic. The 
fork of R:+3 1s often very deep, this cell being in many instances sessile 
or with Ry even retreated back onto the radial sector (as in Molophilus, 
Plate XXXIV, 65-70; Tricyphona, Plate XLII, 178-185; Limnophila 
emmelina, Plate XL, 151; Rhaphidolabis, Plate XLI, 172-174), in which 
ceases the anterior branch of the sector is simple and the posterior 
branch is forked, as in the Ptychopteridae already mentioned. These 
shiftings of the elements of the fork of the radial sector have been 
critically studied by Needham (1908). The radial cross-vein apparently 
is lost only by atrophy; the Cylindrotominae, discussed above, which 
appear to lose this vein by the fusion upon it of adjacent veins, in reality 
have it present and elongated, but simulating a section of vein R;. In 
Eurhamphidia and Rhampholimnobia, of the East Indies, the fork of 
the radial sector occurs far beyond the line of the cord, while in most 
other crane-flies it is before or at this line. The radial-medial cross- 
vein (r-m) is usually present, but if lacking it is accounted for, apparently, 
only by the fusion of Ri+; on My +2 (fig. 128, 1); this fusion may 
be slight or extensive, and occurs in scattered genera in all the sub- 
families of the Tipulidae. The radial-medial cross-vein les distad of the 
medial cross-vein in Conosia and in some species of Rhamphidia. In 
many Dolichopezini (Plate XLIII, 186 and 187), Tipulini (Plate 
XLVIII, 247 and 248), and Cylindrotominae (Plate XXX, 5-8), the 
whole tip of Ry is atrophied. In the remarkable genus Toxorhina (Plate 
XXXIII, 45 and 46), the radial sector is unbranched but the branch that 
persists is undoubtedly Ri+; alone, R2+3; having retreated back toward 
