THE CANADIAN ENTOMOLOGIST. 245 



MAYFLIES OF THE SIPHLONURUS GROUP. 



BY WILBERT A. CLEMENS, ITHACA, N. Y.* 



The nymphs of two interesting" species of mayflies, Siphlonunis 

 (Si phi urns) minis Eaton and Siphlonisca cerodromia Needham, were 

 handed me for description by Mr. C. P. Alexander, who successfully 

 reared them during the summer of 1914 at Northampton, Fulton 

 Co., N. Y. Before describing these nymphs, it seemed desirable 

 to work over the material available in the Siphlonurus group, and 

 the results of this work are given in the following paper. 



The Name Siphlonurus. 



The name Siphlonurus was proposed for a new genus by 

 Eaton in the Ent. Mag., vol. 5, p. 89, 1868. The name was used 

 again by Eaton in the Trans. Ent. Soc, London, 1870, p. 7. But 

 in 1871 in the Trans. Ent. Soc, London, p. 125, the name Siphlurus 

 is used and Siphlonurus (err.) Etn., 1868, given as a synonym. 

 The name Siphloniiriis was not preoccupied and therefore according 

 to the International Code of Zoological Nomenclature, the first 

 name used must stand and the name of the genus should be Siph- 

 lonurus. 



New Genus. 



In 1913 in the Can. Ent.. vol. XLV, p. 338, I described a new 

 species which I referred to the genus Siphlonurus. This species 

 appeared to be nearest to this genus, and as I had no specimens 

 of this genus with which to compare it, I decided to describe it 

 as a Siphlonurus until other material was available for comparison. 

 Now with such material at hand, I find this species shows characters 

 of sufficient value for the erection of a new genus, and for this I 

 propose the name Siphloplecton (defecti\'e-feeler, from the defective 

 condition of the labial palpus). 



Keys. 



The generic keys which follow are simply those parts of the 

 key published by Dr. Needham, Bull. 86, N. Y. State Mus., re- 

 ferring to the Siphlonurus group, modified to include the two genera 

 since proposed. 



*Contribution from the Limnological Laboratory of the Department of 

 Entomology in Cornell liniversity. 

 August. 1015 



