PL XV. — Mayflies of the Family Heptagenince which cling 

 to the stones in running brooks: i, Heptagenia, fullgrown, 

 with black wingpads; 2, Heptagenia, another species. Alay- 

 fly nymphs of Family Heptagenincc which live in the swiftest 

 currents: 3, Iron, fullgrown nymph; 4, Epeorus, showing 

 its transparency just after molting. Note the white simple 

 eyes. 



