The Botany of Iceland - 01.12.1928, Side 57

THE AERIAL ALGÆ OF ICELAND
381
This exceedingty widespread and common species was found by
0strup in 140 samples from Iceland. In most of the above-mentioned
samples I have only seen some few specimens of it, while it was im-
possible to flnd individuals with cell contents in these samples. Conse-
quently I presume that it is a casual guest in the samples and has not
perhaps lived in these localities at all. The samples in which it occurred
in fairly large quantities and in which there were individuals with cell
contents were all derived from places with plenty of moisture. I must
thus consider the species to be a rather pronounced hydrophilous species.
VI. Naviculeæ.
Diploneis Ehrb.
Diploneis oculata Bréb. Cl. Syn. I, p. 92. V. Heurck Syn. Pl. 9,
fig. 10.
E. Icel. L. 92 — N. Icel. L. 217.
Area: Eur.
The specimens I have found of this species are somewhat smaller
than those generally described, viz. 1.13—14/,«, hr. 5,5p, str. 23—27 in lOp.
The two localities in which it occurred differ widely, one being a large
stone in the ravine »Stóra Gjá«, the other the hlað of a farm. In both
places there grew Prasiola, in the first place also mosses. In the litera-
ture this species is recorded as living in fresh water, especially running
water.
Diploneis minuta Boye P. n. sp.
Valva lineari, apicibus rotundatis, long. 13 p, lat. 4,4 ju,
striis delicatissimis, vix visibilibus. Fig. 6.
E. Icel. 7, L. 25.
In this very small species the strongly silicified apical
»horns« are plainly seen, surrounding the raphe. The striæ
are so fine that I have only seen a faint glimpse of them.
They are outside the longitudinal furrows.
Found in the same two samples as Navicula bryophila n.sp.
lli
Fig. 6.
Diploneis
minuta
BoyeP. n.sp.
(X 1200).
Diploneis ovalis Hilse. Cl. Syn. I, p. 92. V. Heurck, Syn. Pl. 10,
fig. 10 b.
E. Icel. 7, 14, 40, L. 77, 78, 92, L. 112 — N. Icel. 1G9 — S. Icel.
L? 294, 295.
Tliere is a gradual transition from D. oualis typica to var. oblongella.
Such transition forms occurred in most of the above-mentioned samples.
The species, which seems to he cosmopolitan, was found by 0strup
in 49 samples from fresh water. According to the data it would thus
seem to be as frequently terrestrial as aquatic. Most of the samples in
which I found it were derived from turf walls or the immediate vicinity
of liouses.