10 ARKIV FÖR ZOOLOGI. BAND 7. N:0 36. 



same small ovale — oblong hind wings, rounded in the point, 

 which are characteristic of the genus Bastis Leach. With 

 this agrees also the statement coneerning its size »cette 

 ephémere est des plus petites». The reason why it has been 

 interpreted as a Leptophlebia has obviously been the men- 

 tioning of »les trois longs filets de la queue», which also are 

 reproduced. The presence of these is the only one of the 

 characters given, which does not seem to be consistent with 

 the interpretation just mentioned. De Geer has, however, 

 also (p. 652) the observation »il arrive quelquefois qu'on 

 trouve de ces Ephémeres qui n'ont que deux filets au derri- 

 ere», but be considers that »celles-la sont mutilées, elles ont 

 perdu le filé t du milieu par quelque accident». In this opi- 

 nion he is notwithstanding mistaken, probably on account 

 of a confusion with some other rather similar form. For an 

 imago of Ephemerida furnished, at the same time, with 3 

 caudal setse, turbinate eyes, and such small hind wings, 

 should be a monster, which does not exist in nature or else 

 is not known at least. 



The correctness of this interpretation of mine has been 

 fully verified through the examination of the received type, 

 imago (^ — the only individual that, according to De Geer's 

 words in the text (»cette petite Ephémere, qui etoit unmäle»), 

 seems to have been in his hand a t the description. For this 

 individual agrees entirely with his description, with the ex- 

 ception of the caudal setse, which are 2 and which apparently 

 have never been more, and is proved to be a Baetis. As 

 far as it is possible to determine the specimen, the species 

 seems to be B. incurvus Bgtn^. 



4. Eyhémere grise en dessous (1. c. pag. 652 — 656. N:o 4). — 

 This species is not Eaton's and other modern systematici's 

 Heptagenia {Ecdyiirus) venosa, but Ecdynrus volitans Eaton. 

 De Geer describes all the stages of development, for which 

 reason it is much more noticeable, that Eaton, who also 

 knew the venosus-lsivvdu, which differs through differently 

 formed tracheal branchise etc, could identify this species 

 with De Geer's. The larva too, as it is described and re- 

 produced by De Geer (1. c. Pl. 18. Fig. 1 — 3) agrees entirely 

 with the larva of Ecd. volitans, which is the only species 



^ S. Bengtsson, Neue Epheraeriden etc. p. 115. 



