The Botany of Iceland - 01.12.1916, Blaðsíða 45

MARINE DIATOMS FROM THE COASTS OF ICELAND
380
In S. W. (witli more than 50%): Rhabd. arc. (66%), Rhabd.
min. (59%), Hyal. subt. scot. (58%), Gramtph. marina (51%)-
In N. (with more than 40%); Rhabd. arc. (79%), Syn. aff. +
var. (51 %), Rhabd. min. (43 %).
In E. (with more than 30%): Rhabd. arc. (68%), Frag. striat.
(38 %), Bidd. aur. (32 %), Syn. aff. + var. (32 %).
This sliows, that Rhabd. arc. ist the most predominant Diatom
along the coasts of Iceland.
CHARACTERISING FORMS.
By »characterising forms« I understand species, which, by their,
frequent occurrence in a sample, may be considered to be charac-
teristic for this. »Characterising forins« are of course far from being
always found in a sample, but on the other hand, several such forms
may very well be present in the same sample.
In the list below, I have given a synopsis showing the genera
or species of Diatoms characteristically associated with the various
genera of Algae. Where a figure is attached to the name of the
Diatom it indicates the number of the samples in which the genus
Rhodophyceæ Number of samples
125
1 Antithamnion 7 Grammatophora (2), Hyalodicus scoticus, Podosira.
2 Bangia 6 Rhabd. arc.
3 Calithamnion 6 Achnanthes, Cocconeis, Grammatophora, Rhoicosphenia
curv., Rhabd. arc. (2), Synedra.
4 Ceramium 9 Amphipleura rutilans, Podosira.
5 Chantransia 10 Cocconeis, Frag. striat., Licmophora (2), Rhabd. arc.,
Rhabd. min. (2), Synedra (2).
6 Delesseria 7 Cocconeis, Isthmia (2).
7 Halosaccion 9 Rhabd. arc., Rhabd. min. (2).
8 Lomentaria 2 Istlimia.
9 Melobesia 3 Grammatophora.
10 Petrocelis 5 Isthmia.
11 Phyllopliora 1 Cocconeis.
12 Polysiphonia Cocconeis (2), Grammatophora (3), Isthmia, Rhabd.
15 arc. (2).
13 Porphyra 10 Licmophora (2), Synedra.
14 Ptilota 4 Cocconeis, Grammatophora.
15 Rhodochorton 19 Cocconeis (2), Gomphonema exiguum, Grammatophora
(3), Rhabd. arc. (3), Rhoicosphenia curv., Synedra (2).
16 Rhodomela 7 Cocconeis (2), Isthmia, Licmophora, Rhabd. arc. (2).
17 lthodymenia 4 Licmophora.
18 Turnerella 1 Bliabd. min.