The Botany of Iceland - 01.12.1928, Side 113

THE AERIAL ALGÆ OF ICELAND
437
same tubular antheridium, so in this it resembles V. borealis. In Borge-
sen’s fig. 3, however, it is distinctly shown Ihat the membrane of the
oospore is papillose which it should not be in V. borealis. Thus Var.
islandica occupies an intermediate position between the two species. Un-
fortunately it proved impossible to procure material of this variety, so
that it has not been possible for me to form any opinion of this form.
I have found V. borealis in two places in Iceland, in both cases on a very
damp substratum, viz. on a rocky wall with an outílow of water (Fljóts-
dalur) and on very damp ground by Lagaríljót. It will hardly survive
any intense desiccation. The species has hitherto only been known from
Finland, but lately Strom has found it in Lapland (1923, p. 457) and
Norway (1926, p. 171).
Vaucheria hamata Walz. Walz 1866, p. 148, Taf. 12, íig. 12—16.
Heering 1907, p. 159.
W. Icel. 307, 338 - S. Icel. 371, 386.
This species is well known for its common occurrence on soil and
is probably distributed over the greater part of the globe. To the areas
mentioned by Heering (1. c.) I can add Jan Mayen (Ostenfeld-
Hansen 1897, p. 23) and Denmark (Boye Petersen 1915, p. 349).
Miss Bristol (1920, p. 46, 75) found il in a single sample of arable
soil which had been dried for öVí weeks. The reason why she did not
íind it in more of the samples is no doubt that the cultivation method
employed has not been favourable to this species. The specimens that
appeared were of less vigorous growth than normal ones.
In Iceland I have found it in 4 samples, two of which were from
soil without any great amount of moisture, viz. from a potato field (338)
and a sheep fold (307). The other two samples, on the other hand, are
from damper places, viz. from the shore of Laugarvatn (371) and the
bed of Gljúfurholtsá.
Vaucheria synandra Woronin. Heering 1907, p. 169. fig. 93.
VestmannaejTjar 399, 410.
This species, which has most frequently been observed on shores
at high water mark, was found somewhat farther away from the in-
fluence of salt water in the two samples mentioned above. One sample
was collected in a small cave formed by the action of the waves, now
situated abt. 20 m above the sea, the other on a rock below a bird-
cliff at a height of abt. 50 m.
Vaucheria sphærospora Nordst. Heering 1907, p. 171, íig. 96.
W. Icel. 343.
Helgi Jónsson mentions (1913, p. 5) that this species occurs as
small cushions on the littoral meadow at Borg, intermixed among the
ofher plants, but it plays no great part there, whereas it forms growths
on the clay flats, partly naked and partly overgrown with scattered
Triglochin maritimum, outside the meadow proper.
The Botany of Iceland. Vol. II.
29