146 KAARE MÜNSTER STRØM. 



IL The Plankton. 



Plankton was collected in the three lakes Kovstulvatn. 

 Nøtingvatn, Toskjærvatn by means of Apsteins quantitative net, 

 (The aperture of the net is 1/80 m^ and it is made of finest millers 

 silk.) All the three lakes are situated at an elevation of ca. 

 3000 feet. — They are small and shallow. (The length of the 

 largest of them, viz. Kovstulvatn is about 1 km. The depth of 

 Kovstulvatn exceeds a maximum of 14 m's, Nøtingvatn is 5 m's 

 deep, Toskjærvatn 9 m's.) — Undoubtedly the water of the lakes 

 is uncontaminated, as they are situated in a quite virgin region, 

 and the geologic formation is quartzite. — The lakes are moderately 

 good for fishing of trout. — Temperature was not measured. 



The plankton of the three lakes proved to be of very 

 little interest. — Of Crustacea, our common plankton-copepode 

 Cyclops scutifer was most abundant, and Holopedium gibberum, 

 Daphnia hyalina subsp., Bosmina obtusirostris, Heter ocope 

 saliens and Naupliece were more or less frequent. — Of the 

 Rotifers, Conochilus volvox and especially Notholca longispina 

 were common. 



The phytoplankton was somewhat poor, and contained only 

 Ghiorophyceæ and Flagellatæ, Only Sphœrocystis Schroeteri 

 was really abundant. — Of the other species, Elakatothrix 

 gelatinosa was especially remarkable, as this alga is previously 

 only known from the western parts of Norway and England. 



The following list shows all the species observed, with the 

 graduations of ccc, cc, c, -f~) r, rr, rrr, in the indication of the 

 frequence of the organism, (ccc means water-bloom, rrr that the 

 organism was only observed in a single specimen.) 



In the definition of the species I have followed G. 0. Sars: 

 An Account of the Crustacea of Norway. Vol's, iv and vi. (Cope- 

 poda calanoida & cyclopoida.), and W. Lilljeborg: Cladocera 

 Sueciæ, for the Crustacea, and the revision by various authors in 

 Brauer: Süsswasserfauna Deutschlands, for the rotifers. 



