KONGL. SV. VET. AKADEMIENS HANDLINGAE. BAND. 20. N:0 5. 53 



TO arrive at any higher deoree of certainty on this point, because the existing state- 

 ments on the distribution of algae south of the Channel are scanty and fluctuating. 



Another reason which seems to speak for the Arctic Sea being an independent 

 centre of development, is the fact that in the Arctic Sea and even in the parts of it 

 situated to the north of the Atlantic there are found some species which are wan- 

 ting in the Atlantic, but occur in the northern part of the Pacific. Such are: 



Delesseria Bterii, 



Petrocelis Middendorffi, 



Rhodymenia pertusa, 



Sarcophyllis arctica, 



Antithamnion boreale, 



Laminaria cuneifolia? 

 » fissilis, 



» solidungula, 



Elachista lubrica. 



The first of these alga3, as is shown by the table of the distribution of the spe- 

 cies, is known from the Greenland Sea, and from the White and the Murman Seas. 

 In the Greenland Sea it ascends to the north coast of Spitzbergen *), though it seems 

 to be rare here; in the eastern Murman Sea it is more common and developed luxu- 

 riantly ^), in the White Sea and the neighbouring part of the western Murman Sea it 

 is one of the commonest algse '). Without the limits of the Arctic Sea it is known with 

 certainty only from the Ochotsh Sea. Another locality reported is Kamtshatka ''). If 

 we should assume that the centre of development of this species were the Pacific, it 

 would become very difficult, not to say impossible, to explain its occurrence in the 

 Arctic Sea north of the Atlantic. It cannot well be supposed to have migrated along 

 the shores, nor to have been carried to its present place by currents. For the current 

 goes from the west towards the east along the coast of Siberia, as has been proved by the 

 researches of the Vega expedition. The alga could possibly have been brought to the 

 American Arctic Sea by the Kurosivo-current, of which at least a feeble branch flows 

 in that direction, but there is no current leading over to the Spitzbergen Sea from the 

 American Sea. If on the contrary we suppose that it has originated in the Arctic 

 Sea, there offers a probable and rather easy explanation, which I shall set forth below, 

 to account for its occurrence in the Ochotsh Sea. It may certainly be objected that 

 the species is known neither from the Siberian nor from the American Arctic Sea; but 

 on the other hand it may be rejoined, that the American Arctic Sea and even the 

 Siberian Sea are little known with regard to algology, and that therefore the species 

 may very well exist in these seas. This is especially probable with regard to the Ame- 

 rican Arctic Sea, because there is found in Baffin Bay a species very nearly related to 

 and very slightly differentiated from D. Bcerii, namely D. corymbosa, which may pos- 



1) Kjellman, Spetsb. Thall. 1, p. 12. 



^) Cp. Kjellman, Algenv. Murm. Meer. p. 13. 



^) Gobi, Algenfl. Weiss. Meer. p. 11. 



*) G. RupRECHT, Alg. Ochot. p. 2.39 follow. 



