6 ARKIV rÖR ZOOLOGI. BAND 7. N:0 36. 



tudine corporis» indicate subimago. The words »culice paulo 

 major» suggest most probably, it scems to me, a Cloeon si- 

 mile Eat. or BaHis Wallengreni Bgtn^, both in Sweden not 

 rare and widely spread species. 



7. Eph. horaria (Fauna Suec. p. 377. N:o 1476. — System. 

 Nat. p. 907. N:o 9). — What Linj^é intended witli this spe- 

 cies, has, no doubt, in my opinion, been Ccenis dimidiaia 

 auct., but he has also, in his description, had before him 

 some representative of the family Baetidce, which he has 

 mistaken for the other species. His description in »Fa^ma» 

 indicates this quite definitely, for as it stånds, it cannot be 

 apphed to any knoAvn representative of Ephemerida. In 

 favour of the determination mentioned speak in the descrip- 

 tion the words »minima», »magnitudo muscae domesticse mi- 

 noris», »alis albis, margine crassiore nigricantibus», »cauda 

 . . . absque ullis parvis (h. e. setis, i. e. forceps) interiectis»^, 

 »pedes albi, exceptis primis majoribus magis fuscis», »ab- 

 domen cinerascens, segmentorum marginibus albis», »vivunt 

 tantum per noctem, moriuntur insequente hora matutina 

 omnes», and »habitat ad lacus» — characters, which, com- 

 bined, are applicable only to the genus Ccenis. Inconsistent 

 with these are »supra oculos tubera duo oculis majora», 

 »habet quasi sex oculos . . . ante tubera positos», a character 

 which belongs only to J^ in the family Baetidce, as well as 

 »cauda biseta». Whether the wings are only 2, is not ex- 

 pressly said, but the meaning seems to be this, as he only 

 speaks about »alis margine nigricantibus». Of the Swedish 

 species of Ccenis Linné's words are applicable only to the 

 common and widely spread C. dimidiaia Steph., which, there- 

 fore, justly, as it seems to me, should take the name of 

 Ccenis horaria (Lin.). 



8. Eyh. diptera (Fauna Suec. p. 377. N:o 1477. — Syst. 

 Nat. p. 907. N:o 11) is Cloeon dipterum auct., $ imago, as is 

 generally supposed. 



9. Eph. nigra (Fauna Suec. p. 377. N:o 1478. — Syst. 

 Nat. p. 907. N:o 7) is doubtful. Eaton identifies it with his 

 Baetis niger, but I have not found this species in our country 



^ Neite Ephemeriden etc. p. 112. 



^ These are, as regards gen. Ccenis, characteristically small and unde- 

 veloped and escape easily one's attention. 



