The Botany of Iceland - 01.12.1928, Side 47

THE AERIAL ALGÆ OI- ICELAND
371
Melosira granulata (Elirb.) Ralfs. O. Muller 1904 p. 267. V. H. Syn.
Pl. 87 flgs. 9—12.
E. Ieel. 123.
Found only in one locality, and the presence of living specimens
was not proved. Is hardly a terrestrial species.
Melosira islandica O. M. Olto Muller 1906 p. 56, Tab. I.
N. Icel. 252.
Seen only in one sample from soil from the interior of Húsavík.
Its occurrence liere must presumably be due to an accident, all the speci-
mens being apparently dead. Not aérial.
Melosira Roeseana Rabli. Meister 1912 p. 40 Tab. I, figs. 4—5.
E. Icel. L. 68, 85, 99, 129 — N. Icel. L. 179, 184.
This species is generally known to occur chiefly on damp rocks
with dripping water and in places where small streams frequently make
their way down (West 1916 p. 423). I have likewise found it in simi-
lar places in E. Iceland, and in a couple of lava caves in N. Iceland.
In these caves there is presumably some protection against strong de-
siccation, and it rnust be permissible to infer that it is a species which
on the one hand requires strong aération to thrive well, but on the
Qther hand will scarcely withstand any very intense desiccation. Its
habitat would also seem to indicate that it hardly needs much organic
or particularly nitrogenous nourishment in order to thrive well.
Melosira varians Ag. Meister 1912 p. 39, Tab. I, fig. 1.
N. Icel. L. 215.
Found in a living state on mud in the ravine »Stóra Gjá« east of
Mvvatn. This mud was quite saturated witli water and since otherwise
the form habitually occurs in water, among algæ and as a coating on
higher plants, stones, palings, etc. it most probably requires plenty of
moisture. Hence it can hardly be regarded as an aérial alga.
PENNATÆ.
I. Meridioneæ.
Meridion Ag.
Meridion circulare Ag. Meister 1912 p. 53, Tab. IV figs. 2—3.
E. Icel. 24, 25, 78, 85, 129 - N. Icel. 133, 161.
Occurred in 7 of my samples, but I only saw dead frustules. As it
is a very common species in Iceland (Ostrup 347 samples), I suppose
that its presence in my samples is due to accidental circumstances, and
it is undoubtedly no terrestrial Diatom.