334 Algae. 



study of the sea during the years of 1902—1909 has until now re- 

 mained in a rather inaccessible and unhandy State as pure lists 

 without any text or general conclusions. Now the bureau has begun 

 the working up of the material by the aid of specialists, and the 

 first part of such a resume has been published in which we find 

 the treatment of the following organisms belonging to the phyto- 

 plankton: Halosphaera viridis, Pliaeocystis Poitchetiij F. glohosa, Dino- 

 bryon diveygens, D. pelliicidmn , Coccölithophora pelagica, Distephaniis 

 speadmn, Dictyocha ßhida and Elvia triparliia, as far as they have 

 been recorded in the area investigated by the international Cooperation. 



Under each species the following headings occur: Bibliography; 

 general features of distribution and biology; distribution within the 

 regions investigated (occurrence, relations to the hydrographical 

 conditions, anomalies in the occurrence); summary and Statement 

 of further observations to be made; economic importance. 



As the material upon which the resume has been made, is a 

 very large one, the conclusions are of general value, and some of 

 them may be recapitulated here in spite of the difificulty of summing 

 up the summary of a resume. 



1. Halosphaera viridis is a holoplanctonic oceanic plankton- 

 organism of a stenohaline and eurythermic character widely distri- 

 buted in the warmer parts of the Atlantic. It is a leading organism 

 for the "Gulf Stream" water and follows it as far north as to the 

 Barents Sea. It has probably not its home in the North Sea pro- 

 per, but is every year carried with the currents from the Faeroe- 

 Shetland Channel into the North Sea; on the other band it 

 does not immigrate through the English Channel, where it is a 

 regulär and common organism all the year round, and it is absent 

 in the Southern North Sea where special hydrographical condi- 

 tions rule. From the quarterly observations it appears that August 

 is the minimum and May the maximum period of its occurrence 

 in the North Sea; four'charts on a plate show the details of the 

 distribution at the four seasons. 



2. Phaeocystis Poiichetii is a northern neritic, stenohaline and 

 stenothermic organism, found along the coasts of the northern North 

 Atlantic, theArctic Sea, Skager Rak, and the North Sea 

 to ca. 55^ Lat. N. More sporadically it occurs in the Kattegat and 

 the Belt Sea. It is a decided spring organism with maximum in 

 Ma}'^ and has a verx'- short duration as plankton. 



's. Phaeocystis glohosa is a neritic, stenohaline and stenothermic 

 organism whose home is in the English Cannel and the North 

 Se^a south of 54°50' Lat. N. Its life-cycle probably resembles that ot 

 the former species. With regard to the North Sea area the distri- 

 bution of Ph. Poiichetii and Ph. globosa exclude each other, the 

 former inhabiting the northern, the latter the southern part. 



4. Dinobryon divergeiis is a freshw^ater organism which is car- 

 ried out by the streams into the most northern parts of the Gulls 

 of Bothnia and Finland; it occurs only in the high summer. 



5. Dinobryon peUucidiiin is a neritic, stenothermic and euryhaline 

 organism of northern character distributed along the coasts ot 

 Greenland, Ireland, Faeroes, Spitzbergen, Nova Zern- 

 bla, Norway and in the Skager Rak, Kattegat and Baltic 

 (but absent iii the area inhabited by nr. 4). In the Arctic regions 

 its flourishing time is in high summer, in the Baltic area April — 

 May. In the Kattegat, Skager Rak and off S. and W. Norway 

 it ma}'^ be used as a leading organism of Baltic water. 



