MARINE DIATOMS FROM THE COASTS OF ICELAND 



389 



In S.W. (with more than 50/u): Rhabd. arc. (66%), Rhabd. 

 min. (59%), Hyal. subt. scot. (58%), Gramtph. marina (51%). 



In N. (with more than 40%): Rhabd. arc. (79%), Syn. nil. -f 

 var. (51 %), Rhabd. min. (43 %). 



In E. (with more than 30%): Rhabd. arc. (68%), Frag, strial. 

 (38 %), Bidd. aur. (32 %), Syn. aff. + var. (32 %). 



This shows, that Rhabd. arc. ist the most predominant Diatom 

 along the coasts of Iceland. 



CHARACTERISING FORMS. 



By characterising forms I understand species, which, by their, 

 frequent occurrence in a sample, may be considered to be charac- 

 teristic for this. Characterising forms are of course far from being 

 always found in a sample, but on the other hand, several such forms 

 may very well be present in the same sample. 



In the list below, I have given a synopsis showing the genera 

 or species of Diatoms characteristically associated with the various 

 genera of Algae. Where a figure is attached to the name of the 

 Diatom it indicates the number of the samples in which the genus 



