The Botany of Iceland - 01.12.1928, Qupperneq 33

THE AERIAL ALGÆ OF ICELAND
357
rum, Plectonema roseolum, Scytonema totypothrichoides, Aphanothece
microscopica.
In one sample 0strup found 15, in the other 40 species of Dia-
toms which were almost all decidedly hydrophilous. At the top of
a hillock in mýri at Vallanes (29) Sligonema minutum, Gloeothece
rnpestris and Nostoc sp. occurred. On anotlier stretch of mýri near
Fig. 1. Stream bed in littoral meadow near Borg. The extensive, tufted mats of
Vaucheria sphœrospora are seen.
Vallanes, in a place where turf had been cut some time before (41),
I found Vaucheria sp. and 11 species of Diatoms, among which
Pinnutaria boreatis was the commonest. A sample (380) from rnýri
at Apavatn contained 12 species of Diatoms, all hydrophilous.
On the whole it may he said that the mýri is rich in species
of Cyanopliyceæ and Diatoms, whicli are almost all hydrophilous;
only on the hillocks, where the algal flora is poorer in species, do
terrestrial forms occur.
h. Littoral Meadows.
The nature and vegetation of the littoral meadow have been
described hy Halgi Jónsson (1913). Its chief characteristic is that
it is occasionally ílooded with salt water, a fact which radically
The Botany of Iceland. Vol. II. 24