36 KAAF^K MÜNSTKK STRØM. M.-N. Kl, 



Order Protococcales. 

 Family Selenastreœ. 

 (ienus (Juadrigula Fkint/ 1915. 

 (JiKuirigitla dosterwidcs (Bohl.) Pkimz. 



Printz: Beitr. z. Kenntn. Chloroph. Sikll. Xorvv. 

 This Alga is a very frequent constituent of our freshwater plankton, 

 especially is this the case in Eastern Norway. It is far more abundant in 

 the plankton than elsewhere. In the lake Vaalesjoen it was extraordinarily 

 frequent. 



Genus Elakdtothri.x Wu.i.k 1898. 

 Wu.le: in Biol. Centralblatt. xviii. 

 Elakatothrix gelatinosa occurred in jolsterxandet in very great quantities. 

 It seems to be a very characteristic Alga in the Caledonian phytoplankton. 

 The principal distribution in our country is on the western slopes of the 

 mountains. I have, however, reported on the species from Tuddal in Tele- 

 mark, where it occurred in quantities. 



Genus Kiniiiicriclla Schmidi.k 1893. 

 Kiniiiicriclla olxsn W- West. 



W. West : New Brit. Freshw. Algæ. 

 The interesting species occurred in Orrevandet in the district Jaederen. 

 It is a species that is much more frequent in the plankton than elsewhere. 



Family Crucigenieæ. 

 Genus Cnicigcuia Morren 1830. 

 Crucigenia irregularis Wille. 



Wille : in Biol. Centralbl. xviii. 

 Crucigenia irregularis was common in X'^aalesjoen, where it occurred 

 in great quantities. I think that this Alga is a true planktonform, but it 

 ma}' also be frequent in the microphytic bottom- vegetation of the lakes. 

 The specific separation between this species and Crucigenia redangttlaris 

 is probably based on insufficient characters, but until a good account of 

 the genus is given I prefer to have them separated. 



Crucigenia reetangularis (Naeg.) Gay. 



The Alga was not so abundant as the preceding species, but occurred 

 in small quantities, in a collection from Svarttjernet in Vestre Gausdal. 



Family Oocystaceœ. 



Genus Oocystis Naegeli 1845. 

 Oocystis crassa Wittr. 



Wittrock: Botaniska Notiser 1880. 

 Oocystis crassa was common in the plankton of a single lake. It seems 

 to be principally a pelagic species, but occurs especially in smaller lakes. 

 — It is by no means very frequent in our plankton. 



