NEW YORK STATE MT T SEUM 



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which they dwell are very diverse. The conditions of adult life 

 are, however, much the same in all; and we find the adults much 

 more alike. The beginner will certainly find them much more 



difficult to distinguish, and would 

 do well to study nymphs and adults 

 together. The critical diagnosis of 

 the species will doubtless rest on the 

 highly individualized genital arma- 

 ture of the male. A suggestion of 

 the strength and definiteness of the 

 characters presented by these parts 

 may be had from reference to the 

 accompanying figure of the male for- 

 ceps and inner appendages of E c d y u r u s m a c u 1 i p e n n i s 

 (fig.10). These project strongly from the ventral side of the apex 

 of the abdomen, and are easily separated therefrom in fresh or 



Fig. 11 Tarsul claws of nymphs of 

 Hep tag eninae ; w, of Hepta- 

 genia inter punctata Say; x, 

 of R h i t h r o g e n a e 1 c g a n t a 1 a 

 Etn. V; y, of Iron sp '/ from <'<>> 

 Glen, Ithaca; z, of EC dy in us 

 maculipenuis Walsh; bind 

 claws in curb case; middle ones 

 would be similar; front ones some- 

 times different 



Fig. 12 Labra of nymphs of Hepta- 

 geninae; h, of IronspV from Coy Glen, 

 Ithaca; i, of Rhithrogena elegan- 

 tula Etn. V; j, of Ecdyurus maculi- 

 pennis Walsh; k, of Heptagenia 

 interpunctata Say 



Fig. 13 Mandibles of nymphs of Hepta- 

 geninae; c, of Rhithrogena elegan- 

 tula Etn. ?; d, of Iron spV from Coy 

 Glen, Ithaca; e, of Ecdyurus maculi- 

 p e n n i s Walsh ; f, of Heptagenia 

 interpunctata Say 



alcoholic specimens by a longitudinal snip with a pair of fine 

 scissors. They may then be permanently mounted on a slide as 

 microscopic preparations so as to give a square ventral view. 

 It is from preparations so made that all the figures of the male 

 appendages in this paper have been drawn. 



