2 ARKIV FÖR ZOOLOGI. BAND 7. NIO 36. 



an explanatory moment, the shortness and incompleteness of 

 the diagnoses, which, generally, only are based upon vague 

 colour-characters and these are often taken from dried indi- 

 vid uals too. 



Many of our Swedish species are, of course, common to 

 those of the neighbouring countries, and since there exists 

 now, through Esb. Petersen's work »Danmarks Fauna. 8. 

 Guldsmede, Dognflner, Slorvinger etc. Kobenhavn 1910» a 

 comparison, of recent date, of the Ephemerida of the Danish 

 .fauna, a safer basis has been obtained also concerning the 

 determination of the forms described by O. F. Muller in 

 Zoolog ice DaniaE Prodroinus. Havniae 1776. The basis of the spe- 

 cies of Ephemerida described by J. C. Fabrtcius in Entomologia 

 Systematica. Tom. II. Hafniae 1793 and in his earlier works is, 

 as is well known, in many cases, material coUected in Den- 

 mark and even in Sweden, and, on account of this, I have 

 also made most of his species a subject for a critical review. 

 Within this setting I have at last also included the species, 

 that are described by H. Ström in »Norske Insecters Be- 

 skrivelse med Anmserkninger. K. Danske Vidensk. Selskabs 

 Skrifter. Ny Sami. Anden Deel. Kjobenhavn 17S3», and which 

 are collected in Nordenfjeldske Norge. 



Of the existing types, upon which the works above men- 

 tioned are based, I have had access to those of de Geer, 

 which are kept in the »Riksmuseum» in Stockholm and which 

 have, for examination, been kindly committed to me by Prof. 

 Dr. Y. Sjöstedt, Intendant of the collections, and to Zet- 

 terstedt's type-collection, which is kept in the Entom. Mu- 

 seum of the university of Lund, a:nd which, like that of de 

 Geer, exclusively contains specimens, stuck on needles. Little 

 or nothing of value seems to be left now of Linné's and 

 Fabricius' types of this group. Whether O. F. Muller has 

 ever had a type-collection, is not known, as far as I am 

 aware. About Muller's collection Hagen ^ has the following 

 statement: »Leider sind die sämmtlichen Sammlungen und 

 Schriften Otto Friedrich Muller's, nach denen ich auf das 

 Eifrigste geforscht habe, ganz verschwunden, und wahrschein- 



^ H. A. Hagen, Nachriclit iiber die entomol. Sammlungen in Norwegen, 

 Schweden imd Dänemark. Stettin. Entom. Zeit. Jahrg. 5. 1844. p. 131. 



