610 



Within the boreal-neritic element I have separated ofr a group 

 to represent, both doubtful neritic forms, and such as are less 

 boreal than the others. In a similar way I have in the temperate- 

 oceanie element marked those species with an asterisk which are 

 more southern than the others. Species regarding the position of 

 which I have been doubtful, are enclosed within parentheses and 

 excluded from the sum total. For comparison I have summed up 

 the forms recorded by Gran from the Norwegian Sea and have 

 referred them to such groups as I in conformity with the Færoese 

 consider them to belong. 



Table X. 



What strikes us most on comparing the two regions is that 

 the arctic species are quite absent around the Færoes 1 . 

 This is easily understood when we consider that the islands are 

 almost constantly surrounded by the waters of the Atlantic and are 

 only occasionally touched by the cold current from off the east 

 coast of Iceland. The middle temperature (off Thorshavn) in Ja- 

 nnary— March is even 5°5C, which is considerably higher than 

 that which is favourable for the arctic Diatoms (0° — 5° C). 



We may further notice that the Færoes have several more 

 oceanic (47) than neritic (37) forms, while the reverse is the 

 case in the Norwegian Sea (51 to 57). This may doubtless be ex- 

 plained by the faet that the Fa>r6es cover a small area and are 

 rather isolated, so that the neritic Flora becomes relatively poor, 

 the present direction of the ocean enrrents is not favourable for the 

 transportation of forms which may thrive on or around the Færoes. 

 It is quite a diffcrent thing in the case of the oceanic plankton- 

 forms which spend their whole life in the open ocean withoul ever 



1 A single specimen of the arctic-neritic form, Fragilaria oceanica, was ob- 

 served once only, but I nm not quite sure as to the correctness of the determination. 



