MAY FLIES AND MIDGES OF NEW YORK 



49 



covers part of the 8th segment ; in d i in i n u t a it does not wholly 

 cover the 7th segment. 



Were it not that these differences of structure of the nymph 

 are so slight I should have thought a separate genus necessai'v 

 for this new species; for the differences in venation and in the 

 genitalia are certainly as gi*eat as usually serve for generic 

 separation. These principal differences may be tabulated as 

 follows: 



Among some mayflies that were kindly collected for me bj 

 Mrs Mary Rogers Miller at Thousand Island Park, on the St 

 Lawrence river, are a number of typical specimens of our two 

 previously' described species, C. diminuta Walker and 

 C. hilaris Say, that fit the descriptions exactly. In ordet 

 to promote accuracy in the determination of the most difficult 

 forms, I have prepared the drawings hei*ewith presented (pl.ll, 

 figs.3-6) of the wings and male genitalia of these species. It 

 ^ill be observed by comparing the wings with Eaton's figures 

 that in venational character ? C. allecta agi^ees better with 

 the Eui^paean genus Tcicorythus and the South Ameri- 

 can genus Leptophyes, than with Caenis . But there 

 are disagreements also with these, and the ^ genitalia and 

 nvmplis of these are as vet not certainlv known. 



leptophlebia praepedita Etn. ? 



This species, hitherto known only from Xew Hampshire and 

 not yet reported from Xew York State, is common about Lake 

 Forest, Illinois, where I have found it in three quite diverse 

 situations: 1) in the Skokie (north branch of Chicago river), a 

 sluggish creek flowing through open meadows and marshes; 



