KONGL. SV. VET. AKADEMIENR HANDLINGAK. BAND, 20. N:0 5. 79 



Monostroma fuscum, Rhizoclonium pachyderinurn, 



» Blyttii, Chsetomorpha Wormskioldii, 



Diplonema percursum, » nielagonium, 



Spongomorpha arcta, Urospora penicilliformis, 



Cladophora rupestris, Rivularia hemisphserica. 



The character of the vegetation is chiefly marked in the province of Spitzbergen by: 

 Alaria grandifolia, Laminaria digitata, 



» membranacea, » nigripes, 



Laminaria Agardhii, » solidungula; 



in the Siberian province by: 



Alaria dolichorhachis, Laminaria solidungula, 



» elliptica, » cuneifolia; 



» ovata, 



in the American province by: 



Fucus vesiculosus, Laminaria atrofulva, 

 Agarum Turneri, » cuneifolia, 



Laminaria longicruris, Alaria. spec? (m.embranacea?) 



This difference of the vegetation of Laminariaceo3 within the different provinces 

 can hardly be explained otherwise than by the supposition that secondary centres of 

 development have been formed within the great arctic centre. Especially in that part 

 of the Arctic Sea denominated the American province, the development of the Flora 

 seems to have taken a direction independent of the others in certain respects. This 

 is, besides, indicated by several other peculiarities of its vegetation, as the occurrence 

 of such species as Kallymenia Pennyi, Antithamnion americanum, Rhodocliorton spinulosum, 

 and Chcetomorpha. Wormskioldii, but, above all, by the species of Delesseria of which 

 no less than three belong exclusively to this province. One of these, D. corymbosa, 

 is nearly related to D. Bcerii, pretty common in the province of Spitzbergen, and is 

 perhaps to be considered as having branched off from this; another, D. Montagnei, is 

 most closely allied to and only slightly- different from D. alata of the Atlantic, whose 

 mother form it may possibly be; and the third, D. rostrata, resembles in habit most 

 nearly Delesseria Bcerii, but in anatomical structure agrees more closely with D. alata 

 or Z). Montagnei, from the latter of which it may be thought to have issued. 



The general conclusion to which my investigation of the Flora of the Arctic Sea, 

 taken in a wide sense, has led me, may be briefly stated thus: the arctic part of the Ocean 

 comprises two separate regions differing with regard to their history of development, 

 one situate on the north coast of Norway and closely connected with the Atlantic, the 

 other arctic, comprehending the rest of the Arctic Sea; in different parts of the arctic 

 region the development of the Flora has been in a certain degree independent, which 

 is especially indicated by the distribution of the Laminariacese ; on this account, the 

 arctic region may be devided into three provinces: that of Spitzbergen, the Siberian, 

 and the American. 



