ICSI. No. 4. THE PHYTOPLAXKTOX OF SOME NORWEGIAN LAKES. 5 



2. September ij. nS'cjS. J'rrtical j iii's. The phytoplankton even 

 richer than in the preceding sample. Staitrastnmi gracile and Ceratiuiii . 

 hirundincUa occurred in immense quantities. — Pedlastntni Boryaimw was 

 common. Together witli tiie regular indixiduals of Ceratiiiiii hiruiidinella 

 occurred resting-spores in quantities. 



9. Nedre S j o d a 1 s \- a n d is situated at an altitude of ca. 1050 m's, 

 in the mountain district between Gudbrandsdalen and Jotunheimen. The 

 whole lake is shallow, the maximum depth being 12,5 m's. — The surroun- 

 dings are chiefly pine and bircli-forests of Alpine character, partially with 

 peaty moors. — A single sample was examined. 



Vertical 12 111 s. August 10. uHc)6. — The phytoplankton was poor, 

 the only Algae which occurred in some quantities were Staiirastnuu para- 

 doxiiii! var. ciiiguliiiii and sterile Moiigrotia-\\\w\wi;nX.^. 



ID. \' a a 1 e s j o e n is a small mountain lake at an elevation of about 

 900 m's in the mountains East of Gudbrandsdalen. The lake is shallow, 

 the maximum depth being 14 m's. — The surrounding area is situated in 

 the tree line. 



l^ertical 12 m's. August in. iSg6. — This lake contained a rich and 

 varied plankton. — The four species Crucigenia irregularis, Aphanocapsa 

 elachista, Aiiabœiia Jlos-aqiuv and Oiiadrigiila closterioidcs were predominant, 

 perhaps Crucigenia irregularis occurred in the greatest abundance. — Other 

 Algæ which also occurred in \er\' gi^eat quantities were Cliroococcus lim- 

 ueticus, Staurastrum parado.xum var. ciuguhiiii and Auahaiui Lemmermamiii. 



11. Besvandet is a lake of considerable size, situated in Jotun- 

 heimen, the highest and wildest mountain district in Norwav, and indeed in the 

 whole of Northern Europe. The altitude is 1466 m's, about 4600 ft. The water 

 is very clear and transparent, and the whole lake is deep with steep shores. 

 The surroundings are mainly the steep sides of high and naked mountains, 

 partiall}' with eternal snow. The shores are to a great extent destitute of 

 any vegetation. The plankton was \-ery interesting and proved clearlv that 

 a great number of Desmids are really eulimnetic plants. To those who be- 

 lieve that all the Desmid-plankton of lakes is deri\-ed from surrounding- 

 peaty moors, and that they will only find suitable conditions for their 

 existence in brown watci\ rich on liumic acids, this lake should be a clear 

 evidence that the matter is not so. One sample was examined. 



Vertical 14 m's. August i j. nSijô. The phytoplankton was rich, and 

 consisted of Peridiiiiuni Ulllri and Desmids, especially Staurastrum jaculi- 

 ferum, Staurastrum proboscidrum, Staurastrum parado.xuiu, a new pelagic 

 form of Arthrodesiuus Incus, Cosnuirium abbreviatum var. plain tonicum, 

 and others. 



12. H e i m d a 1 s V a n d e t is a lake of considerable size situated in the 

 district Jotunheimen, West of Gudbrandsdalen. The altitude above the level 

 of the sea is about 1 1 so m's. 



