808 P. T. CLEVE, SOME ATLANTIC PLANKTON-ORGANISMS. 



Tt is apparent from the above f'acts, that the strictly iion- 

 arctic forras, which occur araong the northern neritic plankton of 

 the Skagerak, inhabit as a rule the area between Scotland, Iceland 

 and Greenland. On arriving off the south side of Iceland, they 

 spread eastwards together with arctic species over the Wywille- 

 ridge to the Färöes and the Shetlands towards western Norway, 

 and westwards into Denmarks Sound and, in several cases, into 

 the Labradorcurrent. Sorae of these species, like the true tricho- 

 plankton forms, occur in the region of the Azores and off the 

 coasts of Europa during the winter and spring. The chief points 

 in the east, where the arctic and boreal forms appear during 

 the winter and spring are at about 50' X. 30^ W., at the 

 northern end of the 3000 ra. plateau around the Azores, above 

 the submarine promontory SW. of Iceland, and off the Azores, 

 the coast of Portugal and Cape Finisterre. 



