82 



[August, 



AN OUTLINE OF A RE-ARRANGEMENT OF THE GENERA OF 

 EPHEMERIDjE. 



BY A. E. EATON, B.A. 



The principal object of the present communication is the settle- 

 ment of the generical nomenclature of the E'pTiemeridw. Their geo- 

 graphical range is only subordinate to the design ; for so circumscribed 

 are the sources whence information on this subject is obtainable, that 

 it would not be worth one's while to treat of this alone. Doubtless 

 the unsightly appearance of the dried insects has something to do with 

 the carelessness with which they are regarded by most collectors, and 

 with the scantiness of our knowledge of their distribution. My notes 

 are limited to the recent genera ; and, unless the contrary is specified, 

 the neuration of the anterior wings alone is taken into consideration. 

 The terminology of the neuration is that of Sundevall, as elucidated in 

 his paper, " Om Insekternas Extremiteter," in the Stockholm Transac- 

 tions for 1862. 



G-enus C-enis, Steph. 



Syn. Bracliycercus, Curt. ; Oxycypha, Burm, &c. 

 Type G. macrura, Steph. 



Distrib. — England, Austria, Sweden, Switzerland; N. China, 

 Ceylon ; Indiana, Florida. 



Genus Teioobtthus,* nov. gen. 

 Syn. Ccd?iis,p., Pict. 

 Type T. varicauda, Koll. Mss. ; Pict. 



Distrib. — Egypt. 



The type of this genus differs from Ccdnis in the neuration of the 

 wings. The anterior rib of the vas ulnare is bipartite. Its posterior 

 division is simple ; but the anterior vein gives off an alternately pin- 

 nate, three-branched veinlet backwards and outwards, near its middle, 

 and forks at the commencement of its apical fourth. These nervures 

 are connected together by numerous cross-veinlets. The second ulnar 

 rib is either bipartite (Savigny, fig. 6), or completely divided (Id. fig. 7), 

 and each of the resulting veins sends two simple veinlets backwards to 

 the outer margin. The anterior vas internum is simple ; the posterior 

 omits two or three simple veinlets backwards (see Savigny, in " Descrip- 

 tion de I'Egypte," ii., Nevropteres, tab. 2, figs. 6 and 7). No posterior 

 wings. 



* Tricorythut (Qr )— tri-Koruthos ^ triple-plumed. 



