The Botany of Iceland - 01.12.1928, Blaðsíða 94

418
JOHS. BOYE PETERSEN
The dimensions of the specimens found range within the following limits:
L. 11— 24/í, br. 2,2—2,8 /t, str. more than 30, carinal dots 11—15 in 10/t.
The species, which has not previousty been found in Iceland, seems
predominantlj' terrestrial there, though it does not grow iu verj' dry
localities.
Nitzschia microcephala Grun. Cl. et Grun. Arct. Diat. p. 96. V. Heurck
Syn. Pl. 69, flg. 21.
W. Icel. L. 337.
This peculiar small species has hitherto only been known from
Europe (Belgium, Germany, Switzerland, Denmark). It was not found
in any great number in the sample.
Nitzschia perpusilla Ilabh. Cl.und Grun. Arct. Diat. p. 99. Van Heurck
Syn. Pl. 69, flg. 8.
E. Icel. 85 — N. lcel. L. 135.
The species has not previously been found in Iceland, and on the
whole little is known as to its distribution and occurrence. Hence it
is difficult to form any opinion as to whether it lives chiefly as a ter-
restrial or as an aquatic species.
Nitzschia sinuata (W. Sm.) Grun. Cl. und Grun. Arct. Diat. p. 82.
Van Heurck Syn. Pl. 60, fig. 11.
E. Icel. 85, 92, 99.
0strup found it in Iceland in 26 samples from fresh
water, hence it is evidently in the main a hydrophilous species.
Nitzschia thermalis Kútz. var. minor Hilse. Cl. und
Grun. Arct. Diat. p. 78. Van Heurck Syn. Pl. 59, fig. 22.
N. Icel. 133.
Found in a dried up ditch south of Akureyri among
pronouncedly terrestrial species.
Nitzschia vermicularis (Kútz.) Grun. var. terrestris
Boye P. n. var.
E. Icel. L. 8.
Valva recta lineari in media parte paululum con-
stricta, apicibus protractis; long. 50—55 /t, lat. 4,5 /t, striis
transversis delicatissimis punctis carinalibus 6—8 in 10 /z.
E facie connectivali visa sigmoidea. Fig. 31.
I only found this form of N. vermicularis in one of
the samples I examined, and it may perhaps belong to
that kind of small forms which several investigators have
found on earth. (Boye Petersen 1915, Bristol 1920,
p. 40, Beger 1927, p. 391). The frequently elongated
carinal dots are a peculiar feature of this form.
Fig.31.
Nitzschia
oermicularis
(Kutz.) Grun.
var. icrrestris
n. var.
(X 1200).