The Botany of Iceland - 01.12.1928, Side 74

398
JOHS. BOYE PETERSEN
This species, which has not previously been found in Iceland or
the Vestmannaejqar, grew on a rock beneath a bird cliff at a height of
abt. 50 m. Cleve and Van Heurck regard it as a brackish water
species.
Naviculœ lineolatœ Cl.
Navicula anglica Ralfs var. minuta Cl. Cl. Syn. II, p. 22.
E. Icel. 124 — N. Icel. 169.
Only dead frustules were found in botli the samples, and the lo-
calities are of such a nature that the frustules majf easily be supposed
to have been carried to thern from water. Hence I consider it most
probable that this form is not well suited for an aérial life.
Navicula cincta (Elirb.) Kutz. Cl. Syn. II, p. 16. Van Heurck Svn.
Pl. VII, figs. 13, 14. Van Heurck Types No. 82.
N. Icel. 217, L. 219 — Vestmannaeyjar L. 401, 403, L. 410.
No doubt it occurs predominantiy in water (Ostrup 49 samples).
The 5 localities in which I found it in Iceland vere all very danip. The
species has heen found both in fresh and brackish water, so it is not
pronouncedly halophilous. The 3 samples frorn the Vestmannaeyjar were
taken from roeks by the shore which could probably he reached by
the salt water spray in stormy weather, while the samples from N. Ice-
land were taken from the interior where the influence of salt water is
inconceivable.
— — var. Heufleri (Grun.) Van Heurck. Cl. Syn. II, p. 16. Van Heurck
Syn. Pl. VII, figs. 12, 15.
E. Icel. 41, 78 — N. Icel. L. 133, L. 135, 137, L. 138, 140, 252 —
N. W. Icel. L. 264, L. 269 — W. Icel.. 321 —Vestmannaeyjar 400, L. 401,
L. 403, L. 408, 409.
As previously pointed out (Boye Petersen 1915, p. 23) this variety
is a pronounced terrestrial form (0strup 1 sample from Iceland). Spe-
cimens corresponding to f. eurta Boye P. were found in samples 133,
138. In several of the localities mentioned it was found living in great
quantity on purely mineral ground, thus especially in sample 138, and
in less marked degree in samples 133, 137, 264, 269, and all the samples
from the Vestmannaeyjar. Hence it hardly requires anj7 great content of
organic substances in the substratum.
— — var. leptocephala Bréb. Cl. Syn. II, p. 17. Van Heurck Types
No. 84.
E. Icel. 7 - N. Icel. L. 133.
Only differs from the type by its more linear form. Is hardly any
pronounced aérial form.