I92I. No. 4- THE PHYTOPLANKTON OF SOME NORWEGIAN LAKES. 7 



18. Figgenel\en is a river of important size in Jæderen, in the 

 south-western part of Norway. The sample was taken between the lake 

 Grudevandet and the ocean. Grudevandet is situated onh' a few metres above 

 the le\el of the sea. The phytoplankton was in qualitative respect the ver}' 

 richest I have ever examined and consisted mainl}- of true plankton-organisms. 

 The most conspicuous constituents were TabeUaria fencstrata vor. astcrio- 

 ncUoidcs, Mclosira imriaiis, TabeUaria flocciilosa, ApJianocapsa dclicatissima, 

 Ccratium liiriiiidiiiclla, Gymnozyga iiwunliforiiiis, Dcsiuidiuiu apfogo)iu)ji, 

 Dfsinidiiini Psnidostrrptoiiniia, Clostcrinui Knctzingii, Staurastnim fiircigc- 

 rmn, Staurastriini paradoxiuii, Micrastcrias Sol and Pediastritm pcrtttsum. 



— Other Algæ, of which two are among the greatest rarities in Europe 

 were present, such as Cosiiiariuni pachydcrmuni var. Æthiopicum, Sfaur- 

 astrum Ariiiscoji, Gonatozygon pilosinn and Gonatozygon anilcatinu. The 

 sample was collected June ii. iSgy. 



19. O r r e \- a n d e t is an important lake in the extreme western part 

 of Jæderen. — It is situated less than a mile from the sea. The surroun- 

 dings are heaths, peat\' moors and sand}' country, sparely covered with vegeta- 

 tion. The lake covers an area of abouts 1 1 1 2 square kilometres, but is 

 very shallow, the maximum depth being only 7 m's. — 



Two samples were examined. 



/. August ij. i8cj-j. The surfaee. — The phytoplankton was rich, 

 in qualitati\e as well as in quantitatixe respect, TabeUaria fencstrata var. 

 asterioneUoides predominating, with great quantities of ApJianocapsa elachista 

 var. conferta. — ApJianocapsa dclicatissima, Microcystis flos-aqucc, Coclo- 

 spJicvriuni Kuctzingianuni, CeratiuniViirundinella, TabeUaria fencstrata and its 

 var. Wille i, SurircUa robust a var. sp len di da, KircJmeriella abe sa, Pediastruni 

 Bo7yanuni and Staurastruni paradoxuni were present in considerable 

 quantities. 



2. October j. i8()S. The surface. The sample was dried up, and 

 it is very possible that the delicate Algae were destroyed by the drying 

 and the boiling with lactic acid. — There was a ^•ery great maximum of 

 TabeUaria fencstrata var. asterioneUoides. 



20. R o s la n d s V a n d is a smaller lake in the immediate \icinity of 

 Orrevand. The physical conditions very much resemble those of Orrevand. 

 The greatest depth is about 9 m's. — A single sample was examined. 



August /j". iSçj. The surface. The plankton was characterized by 

 Oscillatoria tenuis and Diuobryon stipitatuni, with a good deal of Ccratium 

 hiruinliiu-lla and TabeUaria fencstrata. 



21. G rav dais vandet is a rather small lake not far from Bergen. 



— The surroundings are mainly cultivated areas. The lake has but a small 

 average depth, the maximum depth is, however, about 23 m's. 



The surface July 11. i8çy. — The phytoplankton was relatively rich 

 consisting mainly of Oscillatoria tenuis. Benthonic Algæ were frequent, and 



