28 KAAKK MÜNS'IKK STRØM. M.-N. Kl. 



Family Surirellaceæ. 



Oenus Siirirclld '\'\\\\). 1817. 



Siirircl/n hisrriata BKi;r.. 



Tilis Diiilom is (juilc general in the Norwegian freshwater plankton, but 

 it is by no iiieaiis a limnetic fV)rin. 



SiDiir/ld rohiistd var. splendida (Ehrbg.) V. 1 1. 



This species oi' Surirella is a very characteristic feature of our plankton. 

 I think it is a semilimnetic form, but it is very generally Distributed, and 

 often it is a conspicuous constituent of the samples. The diatom is one of 

 the leading forms of the Caledonian plankton, being very frequent also in the 

 British lake-areas. It never obtains very great maximums, but it is present 

 in the most collections and often in quantities. 



Class Chiorophyceæ. 



Order Conjugatœ. 

 Family Mesocarpaceœ. 



Genus Mougcotia Agakdii 1824. 



Mougeotia sp. 

 Sterile specimens of Mougeotia-species were generally distributed 

 throughout the whole area. Only in a few lakes they occurred in abun- 

 dance. Mougcotia is a semilimnetic form, but many specimens seemed to 

 have adapted themselves to a limnetic life, showing coiling of the filaments. 

 I have not observed those peculiar states described by Messrs. West, which 

 they thought were results of an aborted conjugation, but it is possible 

 that they, as well as the coiling up of the filaments are adaptions to the 

 pelagic life. 



Family Desmidiacece. 



Genus Goitafozygoii De Barv 1856. 



Goiiatozygou pilosimi Wolle. 



Wolle: in Bull. Torr. Bot. Club 1882. 

 This species was only present in two samples, but was rather common 

 in one of them. Both samples were from Western Norwa}-. 



PI. I, Fig's 13 — 14. 



Gonatozygon aculcatiun Hastings. 



Hastings: in Amer. Month. Micr. journ. 1892. 



This species, one of the greatest rarities in Europe, occurred in the 

 Figgenelven river. The specimens were quite typical, but varied some- 

 what in size. 



Gonatozygon Kinaliani (Arch.) Rabh. 

 Archer: Suppl. Cat. Desm. 1852. 

 The Alga occurred in small quantities in the Alpine lake Torfinnsvandet. 

 It is principally a benthos form, and doubtless it has a wide distribution 



