MAY PLIES AND MIDGES OF NEW YORK 25 



a In the hind wing the subcostal vein terminates in the 

 costa at hardly more than half the length of the 

 wing, just beyond the obtuse angulation having a 

 thickened margin ; forceps of male more or less dis- 

 tinctly four-.iointed Choroterpes 



hh Vein M2 and the bisector of the cubital fork both tending 

 to attach themselves to the posterior branch of their 

 respective forks; between the latter and vein Cu, 

 are generally some short intercalaries (the cubital 

 region thus being better developed than in group h ) ; 

 caudal setae about as long as the body ; penulti- 

 mate segment of the male forceps longer than the 

 antepenultimate 

 i Veins Cu^ and 1st A separate to base. .Ephmerella 

 ii Veins Cu^ and 1st A fused toward the base 



D r u n e 1 1 a gen. nov. 



gg Hind wings absent Caenis 



ff The intercalaries between the first and second anal veins repre- 

 sented by a series of veinlets, often sinuous or forking, 

 extending directly from the first anal to the wing margin ; 

 costal angulation of hind wing close to the base ; but two 

 Avell-developed caudal setae, the median one being rudi- 

 mentary or wanting ; basal joint of hind tarsi evident but 

 not well developed 

 g Median caudal seta a distinctly segmented rudiment (pl.6, 

 fig.l); forceps of male three-jointed; posterior pro- 

 longation of sternum of ninth segment of abdomen of 

 female bifid at tip 

 h Basal segment of fore tarsus of male shortest; claws of 

 each tarsus unlike each to each ; hind wing with the 

 costal angulation acute, and the fork of the median 

 vein occupying two thirds the length of that vein 



C o 1 b u r u s 

 hh Basal segment of fore tarsus of the male longest ; claws 

 of each tarsus alike ; hind wing with the costal angula- 

 tion obtuse, and the median vein forked through one 



third its length Chirotenetes 



gg Median caudal seta more rudimentary or wanting; forceps 

 of the male distinctly foui'-jointed; posterior prolonga- 

 tion of the sternum of the ninth abdominal segment in 

 the female entire at tip 

 h Claws of each tarsus alike; caudal setae at least one 



half longer than the body Siphlurus 



hh Claws of each tarsus unlike; caudal setae about as 



long as the body in both sexes Ameletus 



dd Median vein apparently simple, its posterior fork (M3) being 

 detached and appearing as an intercalary ; hind wings when 

 present at least twice as long as wide, and provided with 

 but 1-3 longitudinal veins 



