182 
Simmons, Bemarks about tlie Belations of the Floras etc. 
There is another series of genera entered in the table TIII 
left aside as yet, viz. such, as are represented by the same 
species in the Atlantic and the Pacific but wanting in the 
Polar Sea. Of those 4 brown and 2 red ones are only fonnd 
in the northern parts of both oceans, 3 brown and" 11 red 
genera have a wider distribution. Some of the former 6 at 
least must be reckoned as once pertaining to the polar flora. but 
not having been able to stand arctic conditions, they liave. once 
driven away, never returned to their former homej likewise as 
most of the species in table VII. There also are genera re¬ 
presented in both oceans, but by different species. Among thern 
also there probably are descendants front the preglacial-polar 
fiora, but as it can hardly be asserted for most of them that 
their origin is such, I have abstained front enumerating them. 
Hitherto the researches made here have always been in 
accordance with the theories of Ränke (40) quoted above (p. 4—5) 
but there is another point, where something more can doubtless 
be done than he thought possible. As his work has the baltic 
flora and its history for its only object, he has left the relation 
of the atlantic and arctic algae to those of the Pacific quite 
out of consideration. Still I think that if he had drawn the 
latter flora into his comparisons, he would not have conte to 
any such result as (40, p. 98): — —„mögen auch mehrere der 
nach jetzigem Befunde als atlantisch angesprochenen Species 
doch vielleicht ihren Ursprung nördlich der Landbrücke ge¬ 
nommen haben und erst später nach Süden gewandert sein, 
während manche wegen ihrer Verbreitung bis über den Polar¬ 
kreis hinaus jetzt zu den subarktischen gerechnete Art südlich 
der Landbrücke entstanden und erst später in den arktischen 
Ozean eingewandert ist. Dies läßt sich für den Einzelfall nicht 
unterscheiden “. 
Such species as are spread front the Atlantic through the 
Polar Sea to the northern Pacific but not southwards must doubt¬ 
less in tertiary time have had their honte in the seas around 
the pole. Consequently we here have found a way to determine 
where genera and species have had their origin as far as the 
tertiary period is concerned. Indeed we know nothing about 
the preglacial limit between the polar and the pacific flora. but 
it seems necessary to think that there has at least not existed 
any broader and easier connection then, on the contrary perhaps 
there has been still less possibility of interchange of species than by 
way of the present Bering Strait. Else it would be impossible 
to explain the fact, that not a single pacific genus is represented 
in the Polar Sea and the north Atlantic. Had pacific genera 
entered the Polar Sea we would have found some of their species 
also in the northern Atlantic, at least if they had had time to 
spread northward before the glaciation, and it would not be so 
apparent, that there only has been an immigration of tertiarv- 
polar algae to both oceans during glacial time. 
Indeed it would be an unprofitable task to try to determine 
