The Botany of Iceland - 01.12.1928, Side 93

THE AERIAL ALGÆ OF ICELAND
417
Nitzschia Hantzschiana Rabenh. Cl. und Grun. Arct. Diat. p. 99.
Van Heurck Syn. Pl. 69, fig. 1.
N. Icel. L. 217.
Found among mosses on a stone in »Stóra Gjá« near Mývatn. Re-
corded by Hustedt (1922 p. 100) as growing on »fiberrieselte Moosrasen«.
However, it is no doubt predominantly hydrophilous.
Nitzschia fonticola Grun. Cleve und Grunow Arct. Diat. p. 97.
Van Heurck Syn. Pl. 69, flg. 15—19.
E. Icel. 113.
Possibly an accidental intermixture in the sample.
Nitzschia Kiitzingiana Hilse. Cl. und Grun. Arct. Diat. p. 96. V. H.
Syn. Pl. 69, lig. 24-26.
E. Icel. 8 - N. Icel. L. 215, L. 217, L. 241 — \V. Icel. 327 — S. Icel.
381, 386, L. 387 — Vestmannaeyjar 401.
This species is characterised by a slightly silicified valve, lanceolate
with slightly protracted apices. The striæ are very difficult to count.
The dimensions are rather variable, and small forms often occur on earth.
The dimensions of the specimens found ranged within the following
limits: L. 15—28 fi, br. 3,8—4,4 fi, str. very fine, carinal dots 14—18 in 10 /<.
I have found it in Denmark on various substrata, but mostly on
garden and forest soil. 0strup only found it in Iceland in one sample
from fresh water, hence it must be assumed to live a predominantly
terrestrial life in the island, though not in very dry spots. My finds
allow of no conclusion in regard to its requirement of organic nourish-
ment. Moore and Karrer (1919 p. 296) found it in soil down to a
depth of 20 cm.
Nitzschia Palea \V. Sm. Cl. et Grun. Arct. Diat. p. 96. Van Heurck
Syn. Pl. 69, íig. 22 b.
E. Icel. 113, 128.
The specimens found showed the following dimensions: L. 25—33 fi,
br. 3,9—4/t, str. abt. 30, carinal dots 10—12 in 10,«. Ostrup found the
species in 83 samples from fresh water, so it can hardly in any marked
degree be capable of living on the ground in Iceland. I have arrived
at the same result for Denmark. Bristol mentions (1919, p. 98) having
found it alive in a culture of a sample of soil 50 years old; she like-
wise states (1920, p. 71) that she has found it in samples of soil. She
may, however, have confused it with the nearly related species e. g.
N. Kútzingiana. Moore and Carter state (1926, p. 118) that they have
found it living in the earth at a depth of more than 4 feet.
— — var. perminuta Grun. Cl. et Grunow Arct. Diat. p. 97.
E. Icel. 7, 28, 128 — N. Icel.169, 252 - N.W.Icel. 264 - S. Icel. L.386.
Differs from N. Kiilzingiana by the valve being more strongly silici-
fled and narrower, while the carinal dots are as a rule somewhat coarser.