The Botany of Iceland - 01.12.1928, Qupperneq 79

THE AERIAL ALGÆ OF ICELAND
403
Pinnularia Brebissonii Kútz. Cl. Syn. II, p. 78. Van Heurck Syn.
Pl. V, íig. 7.
E. Icel. 75, 129.
Lagerstedt already observed this species on earth and moss in
Spitzbergen, just as I myself have found it on earth in Denmark. In
Iceland, however, it seems predominantly aquatic (0strup 34 samples).
Both the samples in which I found it were derived from damp rocks.
Pinnularia Gandrupii Boye P. Boye Petersen 1924 III, p. 16, fig. 4.
E. Icel. 8 — N. Icel. 218.
This form, which I have previously found in samples from Jan
Majren, only occurred in a few specimens in the above-mentioned samples.
It is questionable whether it is an aérial species. It is very reminiscent
of the forms I have referred to P. appendiculala var. irroraía, and might
perhaps be regarded as a variety of this species.
Pinnularia gracillima Greg. Cl. Sjm. II, p. 74. Van Heurck Syn.
Pl. VI, fig. 24.
E. Icel. 8, L. 25, 77. 78, 85. 92, 99, L. 124, L. 128, L. 129 — N. Icel.
140, 169, 179 — W. Icel. 336 — S. Icel. 353, 372.
The species has hitherto only been known from fresh water. 0strup
found it in 6 samples from fresh water in Iceland. I have observed it
with cell contents in 4 samples (25, 124, 128, 129) all originating from
rocks, 3 of which were overgrown with moss. Thus it is certain that
it can live terrestriallv. In the other samples I have only seen com-
paratively few specimens and none with cell contents. Several of these
samples were from the immediate vicinitv of houses where there is al-
ways plenty of manure. The species would thus seem well able to thrive
under such conditions, whereas it does not seem to require any great
quantity of nitrogenous nourishment.
— — var. interrupta Fontell. Fontell 1916, p. 33, Pl. 2, fig. 45.
P. gracillima Hustedt 1914, p. 74, Taf. II, fig. 43.
E. Icel. 7, 24, 78, 99, 129 — N. Icel. 215, 217.
This variety occurs in several samples in company with the typical
P. gracillima (78, 79, 129), and should perhaps most correctlj' be regarded
as a forma, experience having shown that manj7 species occur in the
genus Pinnularia both with and without transapical fascia. It is very
reminiscent of P. nndulata but differs from the latter by its rostrate,
not capitate, apices. (Cf. Hustedt 1. c.). It seems chieíly to occur in
the same places as the main species.
Pinnularia intermedia Lagerst. Lagerstedt 1873, p. 23, T. I, fig. 3.
Boj'e Petersen 1915, p. 293, fig. 18, 19. Bristol 1920, p. 66, fig. 6—9.
A. S. Atl. T. 313, fig. 28. (non Hustedt 1924, p. 569, Taf. 21, fig. 10).