BENGTSSON, AN ANALYSIS OF DESCRIB. SCANDIN. EPHEMERIDA. 5 



»cauda diiabus setis . . . corpore ipso duplo longioribus, albis» 

 and »pedes nivei» indicate distinctly imago $ . There is said 

 nothing about the colour of the bod}^ in ^^Fauna» and, with 

 the support of the description given in this place only, the 

 species can surely be determined in this way. The matter 

 stånds differently, however, if the addition that is made in 

 •»Syslema» p. 907 after the diagnosis is paid attention to: 

 »alse, ut totum corpus, palhde flavescentes». These charac- 

 ters are not at all applicable to the species mentioned, which 

 has its wings quite vitreous, brownish black ground-colour 

 and besides quite yellow (flava) turbinate eyes in J^ imago. 

 Unfortunately Linné says nothing about the hind wings. 

 All the characters given in the descriptions can be applied 

 only to two Swedish species Centroptilum diaplianum (Mull.) 

 (luteolum auct.) and Cloeon hifidum Bgtn\ both of which 

 have also the same size as hioculatus. Considering that the 

 former is one of the most common May-flies in our country, 

 with a very extensive and common spread, while Cloeon hi- 

 fidum is far less common, it seems to me that there is every 

 probability that Centroptilum diaplianum (Mull.) is the species 

 Linné has intended with his species bioculata. 



5. Eph. fuscata (Fauna Suec. p. 376—7. N:o 1474. — 

 Syst. Nat. p. 907. N:o 6). — This has been misinterpreted 

 as identical with the preceding species. The characters 

 >>caput, thorax, abdominis primum et quatuor ultima seg- 

 menta fusca, gibberes oculares . . . flavi», and the other cha- 

 racters given in the description, with the exception of »caudse 

 setse . . . abdomine breviores», are quite applicable to Baetis 

 hioculatus auct., imago J". The description is obviously found- 

 ed on a specimen mutilated with regard to the caudal setae, 

 because there exists no imago ^ of the fam. Baetidce with 

 the caudal setae »abdomine breviores». Baetis hiocidatus diuct. 

 should, therefore, be named Baetis fuscatus (Lin.). Tiie spe- 

 cies is tolerably common in Sweden. 



6. Eph. cidiciformis (Fauna Suec. p. 377. N:o 1475. — 

 System. Nat. p. 907. N:o 8) is a doubtful form. »Tubercula 2 

 supra oculos crassa magna» indicate J* and surely also a 

 representative of the family Baetidce, as »setae caudae longi- 



^ S Bengtssox, Xeue Ephemeriden ans Schwedeu. Entom. Tidskr. 

 Årg. 33. 1912. p. 109. 



