tlie Generic Xamc Biacliyceicus. 517 



111 'An Introduction to tlie Modern Classification oi; 

 Insects' (ii. Synop. p. 47; 18-10) J. O. Westwood gave full 

 jieneric rank to each of Stc[)liens's unisexual groups Brachij- 

 cerciis (with five species) and Ccenls (with two species), 

 designating as the respective typical species the one first 

 named by Stephens in each, that is to say, making Ephe- 

 mera hreviciiuda, Fabr., the genotype of Brachycercus and 

 Canis wacno'ci, Steph., the genotype of Canis. 



At last, F.-J. Pictet pointed out that the groups Ccenis 

 and Brachycercus were separated only by a sexual character, 

 the males, with long seta3, being referred to Ccenis^ and the 

 corresponding females^ with short setse, forming the genus 

 Brachycercus. He went on to say : — '' Lorsque ensuite on 

 a reconnu que cette brievete des soies est speciale aux 

 fcmelles, et que les males an contraire en out d^enormes, il 

 dcvint necessaire de modifier le nom et les caracteres do ce 

 genre \_Brachycercus~\, et M. Stephens leur donna le nom de 

 Ccenis" (Rht. Nat. Ins. Nevropt.; Fara. fiphem. p. 274.; 

 1845). Pictet was, of course, mistaken as to the supposed 

 necessity for changing Curtis's generic name when the 

 characters of his genus were amplified. 



Dr. H. A. Hagen again treated Brachycercus, Curt., like 

 Oxiicijpha^ Burm., as a synonym of Ccenis, Steph. (Ent. Ann. 

 1863," pp. 8-10). 



Following Pictet, the Kev. A. E. Eaton, in his ' Revisional 

 IMonograph of Recent Ephemeridse or Mayflies/ rejected 

 the name Brachycercus, on the ground that " this name was 

 suitable for the female insect only," and employed for the 

 genus the name proposed for it by Stephens (Trans. Linn. 

 Soc. Loud. 2 ser., Zool. iii. p. 18; 1883). 



In 1909 Prof. Fr. Klapalek used the name Ccenis for the 

 genus in question, and the name C?enida3 for the family 

 which contains it (Brauer's Siisswf. Deutschl., Ephemerida, 



Up to this point in the history of the question the 

 Stephensian name C(cnis\i^(\ been wrongly allowed to usurp 

 the prior claims of Curtis's name Brachycercus. As already 

 related, a change was introduced into the situation in 1917, 

 when Bengtsson separated out the species harrisellus and 

 made it the type of a new genus, Euryccenis; as that 

 genus has the same genotype, however, it is a sim})lc 

 synonym of Brachycercus. Euryccenis is included, without 

 comment, in Dr. Georg Ulmer's " tlbersicht iiber die 

 Gattungen der Ephemeropteren " (Stett. Ent. Zcitg. Ixxxi. 

 pp. 120-122; 1920). 



Before the year 1917, therefore, the generic name BrucJii/- 

 cercus rightly appertained to all those species which had 



