8 ARKIV FÖR ZOOLOGI. BAND 7. N:0 36. 



2. Ephémere noire å ailes hlanches (1. c. pag. 646 — 650. 

 N:o 2). — De Geer liimself considered this species as repre- 

 senting the same as Linné's Ephemera vespertina (Fauna 

 Suec. Ed. 2. N:o 1480) and it has also been interpreted so 

 by most of the following systematici. Just as this one it 

 has, therefore, been a subject for very different opinions. 

 Cf. above under Linné's Eph. vespertina. It is particularly 

 remarkable that Pictet^ considered De Geer's species as 

 representing »une toute au tre species» than Eph. vespertina 

 Lin. and identified it with his Potamanthus Geerii, which, 

 however, as both the description and the figures show, ob- 

 viously is another, although proximal species, which does 

 not occur in Sweden. Contrary to Eph. vespertina Lin., of 

 which only a short description is to be found, referring to 

 the subimago-stage, De Geer has, for his species, given a 

 detailed description of both the larva-, subimago- and imago- 

 stages, by which the identification has been essentially fa- 

 cihtated. In my »Beiträge», above mentioned, I was able to 

 give the description of a form, which obviously, in all its 

 stages of development, came very close to the species de- 

 scribed by De Geer. A form of larva, suggestive of the 

 larva reproduced and described by De Geer and especially 

 distinguished by its curious tracheal branchiae, had not, since 

 his time, been found again. I, therefore, referred De Geer's 

 species, without any hesitation, to the same genus Eupliyurus 

 established in this paper, but dared not identify my species 

 with his. Continued examinations, based upon a more ex- 

 tensive material, have more and more strengthened my opi- 

 nion, that De Geer's species must be the same as my Eu- 

 pliyurus alhitarsis and also, as De Geer supposed, synonymous 

 with Ephemera vespertina Linné. Except this species, there 

 is no one of the Swedish Ephemerida, that can be identified 

 with it. De Geer's description and figures contain, in rea- 

 lity, nothing, which is inconsistent with this interpretation, 

 presuming that, as seems to be indisputable, De Geer has 

 founded his description, concerning the colour, both of larva, 

 subimago and imago, like Linné and probably most of the 

 older authors, on conserved, dried material. The only point 

 of difference, which, perhaps, deserves emphasizing, is that 



^ 1. c. pag. 21 



