KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 20. N:0 5, 57 
with on the west coast of Greenland, are cosmopolitan, if they are understood in that 
extensive sense still usual with algologists, and on this account afford us no clue for 
deciding the question of their origin. One species, Antithamnion floccosum, whose form 
in the Atlantic differs from the Pacific form, might possibly be regarded as having 
issued from A. boreale'), commonly dispersed in the Arctic Sea. Some species, Poly- 
siphonia parasitica, P. nigrescens and Plocamium coccineum, that are also stated to occur 
in the southern hemisphere, have possibly passed from the one sea into the other south 
of America. The present distribution of Callithamnion arbuscula is so limited that no 
conclusion can be drawn from it as to the original native country of the alga; more- 
over it appears in the Pacific in another form than in the Atlantic. Concerning the 
few remaining species, I believe I must refrain at present from uttering any suppositions. 
Thus it has been shown that the arctic marine Flora is rich in endemic species; 
that several species which go far northwards in the Arctic Sea and are widely distri- 
buted there, are only slightly spread southwards in the Atlantic; that there are a 
number of species in the northern part of the Pacific which occur also in the Arctic 
Sea, even in those parts of it which lie north of the Atlantic, but are wanting in 
the Atlantic itself; and that of the species comparatively very numerous, which the 
arctic Flora possesses in common with the northern Atlantic as well as with the northern 
Pacific, a very large proportion consists of such species as are met with in the Arctic 
Sea at high latitudes, amongst them several of the most characteristic forms of the 
Arctic Sea. I think I am justified in drawing from these facts the conclusion that the 
Flora of the arctic part of the Polar Sea is an old Flora and that it has developed 
within the Arctic Sea. But this being so, it ought to be explained why several arctic 
forms are met with at present south of the limits of the Arctic Sea, both in the Atlantic 
and in the northern part of the Pacific. The occurrence of several arctic alge on the 
north-eastern coast of America is easily explained by their having been carried there 
by the cold Labrador current, which moreover makes the external conditions on the 
last-mentioned coast very similar to those in which the alge live in the Arctic Sea. 
But along the European coast of the Atlantic no current runs down from the Arctic 
Sea; on the contrary, a current flows upwards into the Arctic Sea from the Atlantic. 
Even if the occurrence of several arctic alew on this coast might be explained by their 
having wandered southwards along the coast, from the Spitzbergen Sea and the Mur- 
man Sea along the land of the Cisuralian Samoyedes a. s. 0., this explanation cannot 
be applied to the species met with at Iceland, and on the coasts of Great Britain and 
France. The currents between the northern Pacific and the Arctic Sea are favourable 
for carrying alge into the Arctic Sea, but not for transporting them from the Arctic 
Sea into the Pacific. However, the causes of the present distribution of the alge 
in the great divisions of the Ocean need not nor ought to be sought for in the 
conditions now existing on the earth, any more than the causes of the distribution 
of the land-plants. Just as the phanerogamous Flora of Scandinavia contains se- 
veral elements which are remnants from that period when the glacial formation 
extended farther southwards than in our days, those arctic alge occurring in the 
') Compare this species in the special part. 
» 
K. Vet. Akad. Handl. Band. 20. N:o 5. te) 
