1 92 1. No. 4. THE PHYTOPLANKTOX OF SOME NORWEGIAN LAKES. 



^l 



Class Flagellatæ. 

 Order Chrysomonadaceœ. 

 Family Ochromonadacece. 

 Genus Diiiobryoii Ehrisg 1833. 

 Diiiobryoii divergens Imhof. 



Imhof : Jahresber. d. Nat. forsch. Gesellsch. Graubundens. 30 Jahrg. 

 Diiiobryoii divergens was \ery common in the mountain lake Go\-aali- 

 vandet, at Dovre. It is not previously known from Norway. 



Family Chromiilinacece. 

 Genus Mal/omonas Perty 1852. 



Malloinonas producta Iwaxoff. 



IwANOFF : Bull, de I'Acad. Imp. St. Pétersbourg. Vol. xi. 

 The species was present in small quantities in the lake Sognsvandet 

 near Christiania. It has not been recorded from Norway by earlier authors. 



Malloinonas toiisiirata Teilixg. 



Teilixg : Schwedische Planktonalgen. I. 



I am in doubt as to whether the specimens I have seen of a certain 

 Malloinonas really are the Malloinonas toiistirata described by Teiling. As 

 I ha\"e only seen a few specimens, 1 can give no exhaustive account of 

 this rare and interesting Alga. 



Class Diatomeæ. 

 Order Centricœ. 

 Family Rhizosoleniaceæ. 

 Genus Rhizosolenia Ehrbg. 1858. 

 Rhizosoleiiia inorsa W. & G. S. West. 



W. & G. S. West : A comparative Stud}' of the Plankton of some 

 Irish Lakes. 



This species, which is so frequent in the British lakes, occurred in 

 small quantities in a mountain lake in Central Norwa}'. 



Order Pennatœ. 

 Family Fragilariaceæ. 

 Genus Synedra Ehrhc;. 1.83 i . 



Synedra Leniinerinannii W. «S: G. S. West. 



W. & G. S. West : A comp. Study of the Plankton of some Irish Lakes. 



This extraordinary plankton-Diatom was frequent in a single lake. It 

 was originally described from Great Britain, and has not previously been 

 recorded from Norway. The specimens observed agreed exactly in size and 

 form with the type. It may be that it has quite a general distribution, but it 

 has probably been confused with other species in the past. 



