The Botany of Iceland - 01.12.1928, Side 89

THE AERIAL ALGÆ OF ICELAND
413
IX. Epithemieæ.
Epithemia Bréb.
Epithemia Argus Kutz. Meister 1912, p. 198, Taf. 34, íig 3—4.
E. Icel. 28 — W. Icel. 338.
Hardlj' an aérial species.
Epithemia Zebra (Ehrb.) Kutz. Van Heurck Traité, p. 296, Pl. 9,
fig. 357.
E. Icel. 41, 112, 129 - N. Icel. 162, 169, 252 — S. Icel. L. 294.
In Iceland the species is extremely common in fresh water (0strup
264 samples). Only in one of the above-mentioned samples, from the
wall of a house with water trickling down it in rainy weather did I
find specimens with cell contents. Several of the other localities (41, 169)
were very damp. Hence it is hardly probable that tlie species withstands
desiccation well.
Rhopalodia O. Muller.
Rhopalodia gibba (Kutz.) 0. M. Meister 1912, p. 200, Taf. 35, fig. 6.
E. Icel. 24 — N. Icel. L. 169, 179 — W. Icel. 336.
This species is quite predominantly hydrophilous (Ostrup 216
samples), and the specimens found are perhaps for the most part erratic,
except in sample 169, originating from the damp bank of a pool near
Ljósavatn.
Rhopalodia gibberula (Ehrb.) 0. M. Epithemia g. V.H.Traité, p. 297,
Pl. 30, fig. 825.
E. Icel. 24, L. 25, L. 28, 40, 77, 113, L. 124 — N. Icel. 256 — W. Icel.
L. 297, 321, 336, L. 337 — S. Icel. 295, 372.
Only in rather damp localities did I find specimens of this species
which contained chromatophores, viz. among mosses in rocky clefts and
beside a hot spring (Helgavatn). In the other samples there occurred a
greater or less number of empty frustules of the species, but from this
nothing can be inferred with certainty as to its occurrence in the said
localities. It probably has its greatest distribution in fresh water (Ostrup
69 samples), but owing to its comparatively solid valves it will often
occur in a subfossil state. It is known from olden times as a species
that will thrive among mosses, on damp rocks and in similar places
(De Toni).
Rhopalodia parallela O. M. var. minor Meister. Meister 1912, p. 202,
Taf. 35, fig. 10.
E. Icel. 85, 92?
Found on a rocky wall with dripping water in Fljótsdalur. It is
hardly an aérial species.