Simmons, Remarks about the Relatious of the Floras etc. 
191 
of the Polar Sea shows a very near analogy to the floras of 
the arctic lands. That such isolated colonies are lacking as the 
landplants have left in Southern mountains, must be a necessary 
consequence of the absence of such ways southwards for the 
algae as the mountainridges have formed for the landplants, 
and also thereof that in the oceans there are no isolated 
areas with conditions like those of the arctic regions. 
Now it is left to try to trace some of the different stages 
in the postglacial reimmigration of algae to the nortliern seas, 
especially to the present Arctic Sea. We know that changes 
as well in the climate as in the level of sea have taken place 
in postglacial time. Such different periods ouglit to have left 
some marks in the present features of the floras. The tertiary 
polar flora was rather uniform, even if there are some facts that 
seem to indicate certain differences already before the glacial 
period between different parts of the Polar Sea. The present 
arctic marine flora is less uniform, as the above tables of distri- 
bution show, and therefore an attempt to trace the immigration 
back is rather tempting. But it would hardly be possible at 
present to carry out such an investigation into detail, and I 
must restrict myself to try an elucidation of a few points. 
The warm postglacial time, that we know from many evi- 
dences in northern Europe, even from Spitzbergen, must doubt- 
less have greatly influenced the migration of algae. This period 
of warmer climate in connection witli an upheaval of the land, 
that brought Spitzbergen in continuity witli northern Europe, 
has, as Natliorst (36) shows, materially contributed to the colo- 
nization of that archipelage with landplants. Of course also the 
algae have wandered along the then existing coast, and there 
are some species in the Spitzbergen - flora , wliich have in all 
probability reached so far just at that time. Such are Alarm 
esculenta{ ?), Fucus ceranoides, F. serratus , and the now extinct 
Pelvetia canaliculata , that has been found together witli Mytilus 
edulis and Cyprina islandica, which now also are found onlv in 
a subfossil state. Probably there have at that time been more 
Southern species and perhaps also the distinctlv temperate forms 
of the Murman and White Sea date back to the same period. 
That the Laminaria saccharina of northeastern Greenland 
has come thither during equally favourable conditions can hardly 
be doubted. Still it is not to be explained with regard only to 
the present distribution of land and water why it should be 
restricted to the coast north of 69°. I have previously pointed 
out the interesting disposition of the Laminariaceae in east 
Greenland, that seems decidedly to show the influence of a post- 
glacial barrier South of Scoresby Sound, i. e., the old now sub- 
marine ridge has been above sealevel in postglacial time, as the 
distribution of the Laminariaceae and especially of Laut, saccha- 
