241) AMERICAN NEUROPTERA. 



length of the median seta is not of generic importance. Heptagenia 

 agrees with Leptophlebia in having the veins between 8 and 9 inter- 

 calary, therefore, I have grouped the genera together. The tabu- 

 lated differences appear considerable; but the hind tarsus of Lepto- 

 phlebia nearly always shows traces of a basal joint, the number of 

 setae is at most of generic value; the difference in position of the 

 eves holds only for the male. Therefore, I believe that these two 

 genera are more closely related to each other than either is to any 

 other genus in our fauna. The remaining genera, the Ephemera 

 and Siphlurus groups, offer but few important venational distinc- 

 tions; a combination of certain minor characters serve to distinguish 

 the two groups. 



E/phemt rella 1 place with Siphlurus, as in the latter some species 

 have some costal cross-veins indistinct. 1 consider these groups as 

 of tribal value and tabulate them as below: 



1. Hind wings very small or absent, when present over twice as long as broad, 

 with only two or three longitudinal veins, fore wings broad at base, 

 vein 6 simple or the wins ciliated (imago), small species • >. 



Hind wings always present, if small, about as broad as long, many-veined. 

 fore wings narrower at base, broadening beyond, vein 6 always forked. 



wing never ciliated imago) 2. 



•J. Veins 9 and 9 l parallel to anal margin and ending in outer margin, ruesono- 

 tum very large, eyes of % contiguous, two setae Bsetiscini. 



Veins 9 and 9 ' ending in anal margin, not parallel to it, mesonotum not so 

 large. '■$■ 



3. Between Sand 9 four long longitudinal veins subparallel to S, furnished with 



many cross-veins, wings white, eyes of £, separate. £, two seta?, J 

 three setie. usually no cross-vein basad of the intercalary between 



forks of 6 Polymitarcini. 



Between 8 and 9 at most only two longitudinal veins, not very long, nor suit- 

 parallel to 8, and with few. if any. cross-veins, wings not white-. • -4. 



4. Between 8 and 9 the veins mostly intercalary, no series of cross-veins from 9 1 



to margin, 9 is usually connected to branches of 8 (except in very 



small species) Leptophlebini. 



Between 8 and 9 the veins are mostly branches of 8; 9 is usually not connec- 

 ted to branches of 8 5. 



5. No cross-vein basad of the intercalary between forks of 6, 9 not connected to 



branches of 8. no series of cross-veins from 9' to the margin, eyes of 

 % contiguous, basal costal cross-veins often few. indistinct or incom- 

 plete Siphlurini. 



Often a cross-vein basad of the intercalary between forks of 6; a series of 

 veinlets from 9' to the margin, when not. then 9 connected to 

 branches of 8; many basal costal cross-veins, all distinct, eyes of % 

 separate Ephemerini. 



