KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5. 51 



It cannot well be doubted that the real origin of the last-mentioned 7 species is to be 

 placed in the Arctic Sea. Their occurrence on the coast of America south of the Arctic 

 Sea is obviously to be explained by the Labrador current flowing along the coast 

 from the north; it may have carried them down, and it makes moreover the external 

 conditions similar to those under which these algas live in the Arctic Sea. Some of 

 these species, Ptilota pectinata, Fucus evanescens, Laminaria longicruris, Agarum Turmri, 

 and Phyllaria dermatodea, belong to those arctic species which are most commonly 

 dispersed and occur in the greatest masses. They are all found in Baffin Bay, even 

 at high latitudes. Delesseria Montagnei appears also to be a common species in Baffin 

 Bay. At least it is to be found in quite considerable numbers in the collections from 

 Greenland that I have had the opportunity of examining. Fucus edentatus and Anti- 

 thamnion Pylaiscei are also recorded from the same part of the Arctic Sea, but it is 

 still unknown whether they are abundant or not. Thus there remain only two species 

 that have not as yet been found with certainty in the Arctic Sea directly north of their 

 reported American locality: Fucus miclonensis and Phyllaria lorea. The former species, 

 as I understand it, is no properly arctic alga, the latter is on the contrary known from 

 the most arctic parts of the Polar Sea. It is possible that Fucus miclonensis, both that 

 which I have set down under that name from the Norwegian Polar Sea and that which 

 J. G. Agakdh reports from New-Foundland, Spitzbergen, and Greenland, is nothing 

 else than one of the numerous forms in which Fucus evanescens presents itself, or else 

 that Fucus miclonensis from New-Foundland is, in accordance with the opinion of J. G. 

 Agakdh, identical with that form of Fucus, brought home from Greenland and Spitz- 

 bergen, which I think ought to be regarded as a variety of the Fucus evanescens that 

 is commonly dispersed in the Arctic Sea. With regard to Phylloria lorea, I can see 

 no probable reason why it should be supposed to have had its centre of development 

 at New-Foundland or to have come there from the south. On the contrary it may be 

 assumed with very great certainty to have had its origin and centre of development 

 in the Arctic Sea, just as the other species in question. 



With the exception of these species, the others possessed by the Polar Sea in 

 common with the northern Atlantic are known either exclusively from the European 

 coast of the Atlantic or both from here and from the north-eastern coast of America. 

 Amongst these not a few are found in the purely arctic parts of the Polar Sea, reaching 

 here very high latitudes, being widely distributed, occurring often in large numbers, 

 in short, numbering among the most characteric algaj of the Arctic Sea. On following 

 their distribution southwards, some of them are found to disappear immediately south 

 of the limit of the Polar Sea, others go only a few degrees of latitude south of the 

 Polar Circle, others again, though common and luxuriant in the arctic waters, become 

 southwards more and more rare, small and poor. These circumstances apparently in- 

 dicate that those species have had their origin in the Arctic Sea and spread from here 

 to the more northern parts of the Atlantic. The following algas may be quoted as 

 good instances of such species: 



Halosaccion ramentacewn, known from all parts of the Arctic Sea, very common 

 in certain regions, for instance in the eastern part of the Greenland Sea. It goes north- 



