The Botany of Iceland - 01.12.1928, Side 55

THE AERIAL ALGÆ OF ICELAND
379
found, inter alia. in puddles. ln Iceland I have found it in sitnilar loca-
lities, viz. among mosses in a mountain cleft in E. Iceland, and in the
partly desiccated river bed of Gljúfurlioltsá among Vaucheria. The species
will no doubt often he found among the »formations passagéres*.
Achnanthes minutissima Kútz. var. cryptocephala Grun. CI. Syn. II,
p. 188. V. Heurck Syn. Pl. 27, fig. 41-44.
E. Icel. 8. - N. Icel. L. 219.
This form was found in 27 samples by 0strup, so it niust be
supposed that in Iceland it is chieíly aquatic. In sample 219 I found
it in quantity among mosses on a bridle-path.
Achnanthes subsalsa Boye Petersen n. sp.
Vestmannaeyjar L. 399.
Valva late lanceolata, long. 14,3/í, lat. 7,3 fx, striis
23 in 10,u per totam valvam radiantibus. Epitheca
area apicali angusta; area hypothecæ in media parte
ovali, ceterum angusta. Fig. 4.
Found only among Vaucheria and Rhizoclonium in
a mountain cave on Heimaey at a height of abt. 20 m.
Most nearly related to A. delicatula Kútz. but íiner-striated, the striæ are
radial on both valves, and the valve is comparatively broader.
Heteroneis Cl.
Achnanthes marqinulata Grun. Cl. Syn. II, 184. V. Heurck Syn.
PI. 27, íig. 45, 46.
E. Icel. 8, L. 123, L. 124, L. 125, 128, 129, - N. Icel. 160, 169?,
L. 254 - N.W. Icel. 264 — W. Icel. 336.
Area: Norway (Dovre), Russ. Lapl., Arct. Amer., Grl., Jan Mayen.
An alpine-boreal species, onhr known to live in Iceland on the
ground and on rocks, mostly among mosses or Vaucheria, but also oc-
curring on the naked ground, e. g. by the roadside. However, I have
ascertained that it may also occur in running water, thus in samples
from Jan Mayen (Boye Petersen 1924 III, p. 18). Hustedt likewise found
it in water (1922 I, p. 98, 100). In this species the frustule is slightly
silicified, hence it shows itself very hyaline in styrax preparations and
has no doubt often passed unnoticed. In air preparations the striation
appears distinctly, inter alia the short marginal striæ on the epitheca.
By these characters it is distinguished from the otherwise very similar
A.kryophila Boye P. (1924 II, p. 316).
Achnanthes pygmæa (Schum.) Cl. Cl. Syn. II, p. 184. Schumann,
Preuss. Diat. I Nachtr. p. 19, Taf. II, fig. 11. Fig. nostr. 5.
N. W. Icel. L. 268.
The species was first found by Schumann in the Baltic, and judging
from his remark, »truppweise in Schleimmassen auftretendq he must
Fig. 4. Achnanthes
subsalsa Boye P.
n. sp. (X 1200).