The Botany of Iceland - 01.12.1928, Side 73

THE AEHIAL ALGÆ OF ICELAND
397
This species which I have previously found on the ground in Den-
mark is evidently nearly allied to N. pseudobacillum Grun., showing
especially great correspondence with V. Heurck Syn. Pl. 13, fig. 13. The
systematic place of this form has been somewhat dubious (Cl. Syn. I,
p. 137 f.). On measuring the figure tlie following figures result: L. 27//,
br. 7 [i, str. 18 in 10 p in the middle, which is in fairly close agreement
with N. lerreslris wliich, furthermore, has, in fact, valves that are some-
what gibbous in the middle, though this does not appear in the figure
(1. c.) (Judging by the dimensions and description it is not impossible
tliat N. terricola Bristol (1920 p. 67, fig. 15—17) is in reality the same
species). Only found on earth, in Denmark especiallv lield and garden
soil, in Iceland on pure mineral ground.
Naviculœ decipientes Cl.
Navicula subtilissima Cleve Cl. Syn. I, p. 141. Stauroneis linearis
Lagerst. 1873 p. 37, Pl. II, fig- 13.
N. Icel. 217.
Only few specimens observed in the sample. They bore a close
resemblance to the figure of Lagerstedt cited, but did not rescmble
Cleve’s ligure so closely. (1891, p. 37. Pl. II, fig. 15). The dimensions
were somewhat smaller than stated by both authors, viz. L. 17//, br.5,6//.
Naviculiv heterostichœ Cl.
Navicula cocconeiformis Greg. Gl. Syn. II, p. 9. V. Heurck Syn.
Pl. 14, flg. 1.
E. Icel. 125, L. 128, 129 - N. Icel. 217, 256.
According to Gleve, an arctic-alpine species, often found in water,
thus by Ostrup in 13 samples from Iceland. It evidently belongs to
tlie species that thrive well both in water and in damp places on land,
e. g. among mosses and on irrorated rocks.
Naviculœ pnnctatœ Cl.
Navicula pusilla \V. Sm. Cl. Syn. II, p. 41. Van Heurck Syn. Pl. 11,
Hg. 17.
E. Icel. 40 — Vestmannaeyjar L. 403, L. 408, 409. L. 410.
Stated to occur in fresh water as well as in slightly brackish water
(Cl. 1. c.). II is, however, already mentioned bv Pfitzer (after Deby 1879)
as a terrestrial species, and later it was found by Deflandre (1926)
on damp rocks in Normandy. In Iceland, however, it evidently occurs
chiefly in fresh water (0strup 40 Pr.).
Navicuhv orthostichœ Cl.
Navicula gregaria Donk. Cl. Syn. I, p. 108 Van Heurck Svn. Pl.VIII,
flgs. 12-15.
Vestmannaeyjar I.. 410.