MARINE DIATOMS FROM THE COASTS OF ICELAND 



391 



is the most conspicuous form, while Cocconeis takes the lead on the 

 Chlorophyceae. 



When examining how matters stand as regards the occurrence 

 of the characterising forms in the 6 groups of Marine Alga? given by 

 Helgi Jonsson in Bot. of I eel. part 1, pages 58 62, it appears, that in 



Group A, The Arctic Group 



I have found 1 charact. form in 3 samples 



B, The Subarctic Group, Subdiv. I 



B, II 



C, The Boreal-Arctic Group 



D, The Cold-Boreal Group 



E, The Warm-Boreal Group 



13 

 36 

 22 

 37 



1 



- 14 



- 32 



- 17 



- 32 



- 5 



This shows, that the characterising forms are most frequent in 

 groups B, C and D, which agrees well with the paramount European 

 character of the Icelandic coastal Diatom-flora. 



Finally, considering the occurrence of the characterising forms 

 during the different months of the year, as far as this has been given 

 in the samples, the facts are the following: 



