622 

 V. CHRYSOMONADINEAE. 



(by C. H. Ostenfeld). 



14. Dinobryon divergens Imhof, cfr. Lemmermann, Ber. d. deut- 

 schen Botanischen Gesellsch., XVIII, 1900, p. 517, PI. XIX, ligs. 15—20. 



In Sorvaagsvatn a Dinobryon constiluted the main part of the 

 plankton, and it also occurred sparingly in the lake in Kvanhauge. 

 It corresponds very closely with Lemmermann 's (1. c.) figures of 

 D. cylindricum Imhof, var. divergens (Imhof) Lemmerm. 



This species appears to be very widely distributed; it is known 

 throughout the whole of Central Europe, and I have seen it in 

 planklon both from Norway and Iceland; and it is possible that 

 the I), sertnlaria reeorded by N. Wille 1 from Norway and by 

 O. Borge 2 and A. Cleve 3 from Sweden is identical with this 

 species. 



VI. PERIDINIACEAE. 



(by C. H. Ostenfeld). 



In none of the samples which have been examined does the 

 Peridiniaceae bear any prominent part, but 3 species in all have 

 been found, one of which, Peridiniiun Willei appears to occur in 

 most of the Iakes. 



15. Peridinium Willei Huitfelt-Kaas, Die limnetischen Peridineen 



in norwegischen Binnenseen, Christiania Vidensk. 



Selsk. Skrifter, 1900, No. 2, p. 5, figs. 6—9. 



This species of which Huitfelt-Kaas gives 

 an exhaustive description accompanied by good 

 figures, was first found in the Norwegian lakes 



Fig. 150. Peridinium Willei 



Huitf-Kaas. The arrange- where none of the other coiiimon species ol 

 ment of ti,c piatea of the Europe, p fabulatum and P. cinctum have been 



distal limb. (C. H. O. del.) l ' 



reeorded. It might be concluded therefore that 

 the Norwegian species is only a form of one of these, P. cinc- 

 tum, which it closely resembles in outward shape. I examined 

 the material very carefully in order to ascertain the distribution of 

 the piates, and for comparison I made usc of Danish material of 

 P. cinctum which Dr. Wesen berg-Lund kindly placed at my 



1 Wille, N.: Algolog. Notizen VII, Nyt Magaz., f. Naturvid., Vol. 39, 1901, p.21. 



Borge, ().: 1. c, pp. 22, 23, 26. 

 s Cleve, Astrid: Plankton <>r lakes in Lule Lappmark, ()IV. af K. Svenska 

 Vet. Akad. Forhandl., 1899, pp. 828— 835. 



