1921. No. 4. THE PlIVTOPLANKTOX OF SOMK XORWEtilAN LAKES. 9 



27. H O f 1 a n d S \' a n d e t is a small lake in the neighbourhood ot the 

 preceding. The surroundings are steep hills, and also culti\-ated areas. The 

 water is of a strong brown colour, owing to the large peat-moors in the 

 vicinity. — The lake is relatively deep (compared with the small size, only 

 one square kilometre), up to 57 m's. 



The surface. Jmir 6. iSgj. — Phytoplankton poor, Spluvrocystis 

 Scliroctcri the only x\lga which was really common, but Ccrotinnt am^irostir 

 and Staiirastnmi (Diatiuuiu occurred to some extent. 



28. J o 1 s t e r V a n d e t is a large lake in die district Sondtjord in 

 Sogn og Fjordane. The length is more than 30 kilometres, and the breadth 

 2 kilometres. The depth is up to 183 m's. It is situated at an elevation 

 of about 220 m's, and the mountains in the immediate vicinity rise to 1700 m's. 

 — The vast Jostedalsbræ glacier, the largest glacier on the European Conti- 

 nent, is in the, neighbourhood, and great parts of the lake possess a green colour 

 caused by water from the glacier. — Two plankton collections were examined, 

 both collected on the same day, July 2j. iSgy, one vertical from a depth 

 of 25 m's, the other from a depth of j 00 m's. — The collections contained 

 Staurastrimi jaculifcniiii, in its bi- and triradiate forms, Diiiobryon cyliiidri- 

 ci/iii and E/akafof/?rix ge/aiiiiosa in prodigious quantities. Other noteworthy 

 Algae were S/>/i(rro(ysfis Sc/irocfcr/, Staurastniiii luegacaiithufu i'or. Scotiaiui, 

 Staitrasfiiiiii liinatiiDi luir. plaiictoniciiiu, Staiirastniiii ciin'otiiiii and Arthro- 

 (/rsiNiis triivigiilaris vor. s!i/)fri(i//g///ans fonua iriqucira. 



III. LIST OF THE SPECIES AND THEIR FREQUENCY 



IN THE LAKES. 



This list is prepared for an easy comparison between the difterent 

 lakes. The indication of the frequency is made, as usual, b}- the gradua- 

 tions ccc, cc, c, r, rr, of which ccc means that the organism occurred in 

 such quantities as to cause water-bloom, or to be absolutely predominating 

 in the collection. — One must, however, always remember that these gradua- 

 tions are quite subjective, and of no absolute value. — I have tried make 

 the graduations with the outmost care, so that their relative value might 

 be as great as possible. To show the relative positions of the lakes on 

 the map of Southern Norway, a map with all the names is prepared. 



(Page 24.) 



