76 KJELLMAN, THE ALGH OF THE ARCTIC SEA. 
in the northern part of the Atlantic, besides in the present glacial region, it is difficult 
to form any decisive conclusion. It seems probable, however, that a considerable 
number of these must or may be thought to have developed in the Arctic Sea and to 
have migrated from there southwards. In any case, the number of those species of 
the arctic marine Flora whose origin must be placed within the Arctic Sea, cannot be 
estimated at less than about 100 species, i. e. about 60 per cent of the total number 
of the species. 
In comparison with other northern Floras, the arctic Flora is proportionally poor 
in Floridew, rich in Chlorophyllophycee and especially in Fucoidex. This is shown by 
the following list: 
Theiler The Flora The Flora 
The arctic of the The Flora of NT The Flora at 
5 : ; seh of New- of Great _ A 
Flora, Norwegian |Scandinavia. ’) E 5 Brot Cherbourg. *) 
oe ingland, *) Britain. 4) 
Polar Sea. 
Floridez are, of the total number of the 
speciese I-03 %t_._ Gs. eee By 37 % 41 % 42 % 43 % 49 % 46 % 
Mncoidesie. 5.945 ¢8 m2 See Pee 37 » 3D » 3D » 25 » 25 » 28 » 
l*@hiorophyllicphycecessss-s--ee-. tee ree eens 21 » 21 » 19 » 18 » ida) 13 » 5) | 
Of the. Nostochinee I shall not speak here, their marine species being still too 
little studied, and the determination of the species being more fluctuating in this group 
of alge than in any other. Nearly a third part of the Fucoidew belongs to the same 
family, the Laminariacew, the richest in species of all the families of the arctic Flora, 
with 20 species, among which one Chorda. In the Scandinavian Flora this family pos- 
sesses with certainty no more than 10 species, amongst which are three species of 
Chorda, on the coasts of England only 7, at Cherbourg 5, including at the two last- 
imentioned places one species of Chorda. On the north-eastern coast of America the 
Laminariacez are more numerous. But it is impossible at present to state with cer- 
tainty the number of their species there. However, it does not probably amount to 
more than half of the arctic. 
The average number of species in the families is somewhat less in the arctic Flora 
than in the Scandinavian. In the former there are about 5,! species in each family, in 
the latter 6,1. However, the Scandinavian Flora contains comparatively more (38 %) 
families with only a single species, than the arctic (26%). Of the 34 families of the 
arctic Flora 2 are monotypical, of the 47 families of the Scandinavian Flora only 38 
1) Cp. Enum. Plant. Scand. 
*) Cp. Farrow, New-Engl. Alg. p. 184. 
3) Cp. Harvey, Phyc. Brit. 
4) Cp. Le Jouts, List. Alg. Cherb. 
») To these figures, of course, only a relative value can be assigned, as | have used the statements given in 
the works quoted, without allowing for differences in the determination of species or the alterations suffered 
by the figures exhibited, in consequence of new species having been added after the publication of the 
works. But notwithstanding this, the proportion between the series in question is no doubt correctly ex- 
pressed in the main by the figures given, as a reduction or addition may be supposed to have taken 
place in an equal degree with regard to all, 
