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NEW YORK STATE MUSEUM 



While the breedings of mayflies now to be reported upon are 

 not very numerous, they could hardly be better distributed for 

 the purpose of supplementing existing knowledge. The C h i r o- 

 tenetes life history is the most important, because of the 

 difficulties and discord it clears away. It is well supplemented 

 by the breeding of A m e 1 e t u s, which shows that to this 

 genus belongs the nymph that Eaton referred by supposition 

 to Chirotenetes (Monograph, pl.lO) . Furthermore, the 

 other new life histories represent additional genera or very 

 striking species. A few notes are added concerning species 

 whose life histories have been previously known. 



The following notes and descriptions follow no systematic 

 order of arrangement, but are ordered as was convenient in writ- 

 ing them : 



Baetisca obesa A^'alsh 



This singular mayfly, known hitherto from Rock Island, Illi- 

 nois and Indiana^ the place of its discovery, has been found at 



two places in New^ York State: In the 

 Niagara river, by Mr E. P. Van Duzee 

 of Bufl'alo, and at Newport, where a 

 single njinph was taken May 30, 1902, 

 by Mr D. B. Young and is now in the 

 New York State Museum collection. 

 I have also received specimens from 

 Mr R. J. Weith, taken in the St Joe 

 river at Elkhart, Indiana, but only a 

 few subimagos, however. The rather 

 stl-iking color pattern of the wing 

 of the male subimago (in the imago 

 the wing is wholly hyaline) is well shown in the accompanying 

 figure reproduced from a photograph (pl.4, fig.l). I present 

 on the same plate (fig.2) a new figure of the nymph also. It is 

 absolutely unique among mayfly nymphs. Its huge four-spined 

 carapace is formed by a backward prolongation of the thoracic 

 dorsum. It meets a conspicuous pyramidal elevation on the 

 middle of the abdomen to inclose a respiratory chamber, within 

 which the gills are included. The labium (fig.4) is most inter- 



Fig. 4 The nympal labium of 

 Baetisca obesa Say. (The 

 two muscle bands indicated by 

 dotted lines in the basal segment 

 of the left palpus are the same 

 that move the lateral lobe of the 

 dragonHy labium) 



