24 NEW YORK STATE MUSEUM 



e Basal segment of the male hind tarsus longer than the third 



segment Rhithrogena 



ce Basal segment of the male hind tarsus shorter than the third 



segment Heptagenia 



II) Hind tarsi usually with but four freely movable segments, the basal 

 segment being more or less completely consolidated with the 

 tibia ; eyes of the male enlarged, often approximated on the dorsal 

 side and divided into superior and lateral portions with corueal 

 facets of different size; venation various, sometimes greatly re- 

 duced: intercalary veins between the first and second anal never 



as in & above Baetinae 



c The three anal veins nearly parallel to the hind margin of the wing 

 and to each other, ending in the outer margin ; in the hind wing 

 the branches of the radial vein are strongly unilateral on the an- 

 terior side Baetisca 



cc Anal veins strongly divergent distally, usually both the second and 

 the third ending in the hind margin; forks of the radial vein in 

 tbe hind wing more symmetrical 



d The median vein with a normal fork ; hind wings, when present, 

 usually but little longer than broad and with a copious 

 venation 



f The intercalaries between the first and second anal veins 

 variable, but usually more or less independent, and not 

 directly dependent from the first anal ; three well-devel- 

 oped caudal setae (except in Bias turns, in our 

 fauna) 

 g Hind wings present 



li Vein Mo and bisector of the cubital fork independent ; 

 between the latter and vein Cu 2 no intercalaries ; vein 

 Cu. in the bind wing rarely preserved; caudal setae 

 generally much longer than the body; penultimate 

 segment of the male forceps shorter than the ante 

 penultimate 

 i In the hind wing the subcostal vein reaches nearly to 



the wing apex ; male forceps three-jointed 

 / Hind wing with a slight concavity at the middle of 

 costal margin ; 5-0 longitudinal veins between 

 R 2 and R 5 ; veinlets numerous about the wing 

 margins and crossveins numerous in the hind 

 wings 



A- Third anal vein of the hind wing wanting; caudal 



setae of about equal length ....Leptophlebia 



/,/,- Third anal vein of the hind wing present, and often 



followed by one or two additional intercalaries; 



median caudal seta distinctly shorter than the 



others B 1 a s t u r u s 



jj Hind wing with an angular lobe projecting forward 

 from the middle of the costal margin ; 4 longitud- 

 inal veins between R 2 and R 5 ; wing margins free 

 from veinlets, and few crossveins in hind wing 



Habrophlebia 



