248 NEW YORK STATE MUSEUM 
Limnobia, Geranomyia, Dicranomyia in part and Rhipidia.@ 
ee Sc atrophied, Rs long and straight to its: origin 
f Rs two branched; cross veins ry and m present, Cu and rst A 
not fused beyond the base, wing widest just before the 
CONC Seah eb ret earn 5 Set aap are ag Seg Antocha 
ff Rs unbranched: cross veins r and m wanting. Cu and rst A 
fused for a long distance at base, wing widest just beyond the 
(ote) 1d oan nie na Rat. tr SAMI a TaN Pure igen Gana Bas oct Toxorrhina 
aI find no venational characters that will separate this group of genera. Rhipidia is 
well distinguished by the possession of pectinated antennae in the male; Geranomyia, by 
the possession of a rostrum as long as the body; and while the length of Sc has been used 
to separate Limnobia from Dicranomyia, it is not a sure criterion, for all sorts of inter- 
gradations occur. In the former Sc is rarely reduced as far as the base of Rs, and in the 
latter Sc rarely extends a little beyond the base of Rs. Clearly Dicranomyia is poly- 
morphic, as this key indicates, and as has before been pointed out in my discussion of D. 
cinerea Doane. Perhaps it has become a little more so now by my addition to it of 
?’D. whartoni. This species has nothing to do with D. cinerea, but represent 
(after D. longipennis O.S.) the extreme of vein reduction along another line. 
