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 Ro and R3 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 generahzed members of this aberrant 

 tribe. In a few species of Gonomyia related to G. blanda (Plate 

 XXXVI, 89 and 90), R2 is very close to Ri 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 R2 + 3 is often very deep, this cell being in many instances sessile 

 or with R2 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 

 cases 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 reahty 

 have it present and elongated, but simulating a section of vein Ri. 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-rn) is usually present, but if lacking it is accounted for, apparently, 

 only by the fusion of Ri + f,on Mi +2 (fig- 128, i); 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 lies distad of the 

 medial cross-vein in Conosia and in some species of Rhamphidia. In 

 many DoHchopezini (Plate XLIII, 186 and 187), Tipulini (Plate 

 XLVIII, 247 and 248), and CyUndrotominae (Plate XXX, 5-8), the 

 whole tip of Ri 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 + 5 alone, R2 + 3 having retreated back toward 



