The Botany of Iceland - 01.12.1916, Page 47

MARINE DIATOMS FROM THE COASTS OF ICELAND
391
Chlorophyceæ Number of samples
92
1 Acrosiphonia 25 Cocconeis (8), Licmophora (3), Frag. striat., Rhabd. arc. (4), Synedra.
2 Chætomorpha 2 Cocconeis, Rhabd. arc.
3 Cladophora 15 Amphora, Cocconeis (6), Synedra.
4 Codiolum 2 Frag. striat.
5 Enteromorpha 20 Achnanthes, Cocconeis (2), Melosira num.. Navicula bottnica, Rhab. min. (2), Synedra (3).
6 Monostroma 11 Frag. striat., Melosira num.
7 Ochlochæte 1 Cocconeis, Synedra.
8 Rhizoclonium 5 Achnanthes (2), Cocconeis, Navicula pusilla.
9 Ulvella 1 Frag. striat.
10 Urospora 10 Biddulphia aur., Fragil. striat. (2), Licmophora (2), Rhabd. min.
is the most conspicuous form, while Cocconeis takes the lead on the
Chlorophyceae.
When examining how matters stand as regards the occurrence
of the characterising forms in the 6 groups of Marine Algæ given by
Helgi Jónsson in Bot. of Icel. part 1, pages 58—62, it appears, that in
Group A, The Arctic Group I have found 1 charact. form in 3 samples
B, The Subarctic Group, Suhdiv. 1 — — 13 — — - 14
B, — — — II — — 36 — — - 32
c, The Boreal-Arctic Group — — 22 — — - 17
D, The Cold-Boreal Group — 37 — — - 32
E, The Warm-Boreal Group — — 1 — — - 5
This shows, that the characterising forms are most frequent in
groups B, C and D, which agrees well with the paramount European
character of the Icelandic coastal Diatom-flora.
Finally, considering the occurrence of the characterising forms
during the different months of the year, as far as this has been given
in the samples, the facts are the following:
Number of samples Charact. forms % Number of samples Charact. forms °/o
January 3 i 33 July 57 12 21
Februar 0 0 0 August 51 14 27
10 5 50 42 19 45
April 37 16 43 Oetober 18 2 11
May 72 27 38 November 0 0 0
June 107 37 35 December 0 0 0