The Botany of Iceland - 01.12.1928, Qupperneq 87

THE AERIAL ALGÆ OF ICELAND
411
According to De Toni this spccies was found on damp limestone
rocks, and v. Schönfeldt (1913, p. 122) gives similar habitats. The
sample mentioned above was taken from a rocky slope by Síglufjörður,
bearing evidence that water at times trickled down it. At the time when
the sample was taken, it was, however, quite dry.
Gomphonema parvulum Kutz. Cl. Syn. I, p. 180. V. H. Syn. Pl. 25fig. 9.
E. Icel. 85 — N. Icel. 140 — S. Icel. L. 386, L. 387.
-----var. exilissima Grun, Cl. 1. c. Van Heurck Syn. Pl. 25, flg. 12.
S. Icel. 295, 327.
-----var. subelliptica Cl. Cl. 1. c.
S. Icel. L. 386.
This species, which is very common in fresh water (0strup 160
samples), is, like the other Gomphonema species, probably no true aérial
alga. De Toni e Forti (1909, p. 22) mention having found it on earth
near a hot spring in Africa. Of the above samples those in which it
was found with cell contents were taken in very damp localities, espe-
cially No. 386 from the bed of Gljúfurholtsá which is partly dry in
summer, it is true, but where the soil is still quite saturated with water.
VIII. Cymbelleæ.
Cymbella Ag.
Cymbella æqualis W. Sm. Cl. Syn. I, p. 170. C. subæqualis Grun.
V. Heurck Syn. Suppl. A. flg. 1. ?Hustedt 1924, Taf. 22, fig. 11.
E. Icel. L. 14, 85, L.? 113, - N. Icel. 140 - S. Icel. 295?.
The species is probably spread all over the globe, but it never
seems to occur with great frequency. In Iceland it was found in 12
samples by Ostrup. Thus it is evidently no very pronounced aérial
alga. The 3 localities mentioned above are from the immediate vicinity
of houses where there must be supposed to be plenty of nitrogenous
substance at disposal. The fourth sample is from a dripping rock, and
the fifth from a »formation passagére«.
Cymbella incerta Grun. var. naviculacea Grun. Gl. Syn. I, p. 170.
C. naviculacea Cleve 1881, p. 13, Pl. XVI, fig. 11.
E. Icel. L.? 77, 112, L. 114, 125.
On the whole this species seems to be rare. Ostrup found it in
4 samples from Iceland. It would seem probable, then, that it is most
frequently an aérial alga in Iceland. 3 of the samples given above are
from houses and their immediate vicinity (house-wall, stone fence, earth),
while the 4th is from naked éarth by the roadside.