MAY K!.li:s AM) MIIKIKS UK XK\V YoKK IT 



</(/ No closed cell in (ho lirsl t'<>rk [' Ihe r:nli;il 



sector iiei'oiv the base of the second divi- 

 sion of the sector ipl.o, lig.3); coxae of 

 fore legs shorter than femora 



1' a 1 in u 1) i u s n. tfen. type 11. ami < n 1 u s Fitch 

 cc First of the three or four divisions of the radial 

 sector arising well beyond the hasal snli- 

 cosi;il erossvein (pl.i!, lig.l); iu the hind 

 wing vein MJ is more or less coiitluent 

 with the base of the radial sector, elimi- 

 nating or reducing the crossvein be- 

 tween 1 1 e m e r o b i u s 



EPHEMERIDAE 



i;\ JAMES G. NEEUIIAM 



Cilice the publication of Museum Bulletin 47 little atteution 

 has beeu given by the workers at the Entomologic Field (Station 

 to the collection and rearing of mayflies. Incidentally, however, 

 a number of new and most interesting forms have been brought 

 together, and nine additional species representing as many addi- 

 tional genera have been reared mostly b}' Mr Betten and myself 

 during the summer of 1901 at Ithaca. It is the purpose of this 

 paper to give the results of new life history studies, and also new 

 keys for both adults and nymphs, that shall serve as a better 

 introduction to the study of this interesting group. 



That the group is of great economic importance in water culture 

 i here can be no doubt. 1'ast food studies have demonstrated 

 this; and every aquatic collector has found the waters teeming 

 with the immature stages. There are mayfly nymphs for every 

 sort of situation in fresh water, and they are almost everywhere 

 abundant. These are perhaps the dominant insect herbivores of 

 fresh water. Notwithstanding their ecological interest, the won- 

 derful ways in which they have adapted themselves to diverse 

 modes of life in different sorts of places, and their singular, 

 though fragile, beauty, their study is very much neglected among 

 us. It is in the hope of interesting more of our field workers in 

 them that I have added to the life histories and descriptions, 

 the keys and text figures of the present paper. 



Few life histories of American species, whose nymphs have been 

 positively determined by rearing, have as yet been written. Tin- 

 singular nymph of T5 a e t i s c a obesa Say has long boon 



