The Botany of Iceland - 01.12.1928, Side 83

THE AERIAL ALGÆ OF ICELAND
407
307, 309 a, 338) in places where the presence of abundant
organic nourishment is probable, and likewise several times
near hot springs (samples 215, 217, 321, 3(54), but whether
these finds give any reliable picture of the life conditions
under which it thrives best seems to me doubtful.
P. molaris shows great resemblance to small forms of
P. Brelnssonii, but in the latter the striation is strongly di-
and convergent, whereas, in the small forms of P. molaris
the striation is almost parallel. Two such small specimens
are shown in fig. 26.
Fig. 26.
Pinnularia
molaris
Grun.
(X 1200)
Pinnularia muscicola Boye P. n. sp.
Valva lineari, levissime capitata, long. 9,5 fi,
lat. 2,3 fi, striis 18 in 10 fi, parallelis; area apicali angusta.
Fig. 27. Fig' 27'
Pinnularia E. Icel. 123.
muscicola
n-sp. This small species I only found in one of the samples
(X 1200). jiere ,jea][ but I also found it in some of the samples of
soil which Mr. Molholm-Hansen brought home to me. This proves
that the species occurs on earth in several places in Iceland.
Pinnularia parva (Grcg.) Cl. var. Lagerstedtii Cl. f. interrupta n. f.
A. Schm. Atl. Pl. 44, flg. 57? Fig. nostr. 28.
Vestmannaeyjar 401, L. 408, 409, 410.
Pinnularia parua var. Lagerstedtii was first described t)y Lagerstedt
(1873, p. 26, Tab. II, fig. 4) as Navicula parvula from Spitzbergen and
Beeren Eiland where it was found on »earth and mos-
ses«. Cleve (Syn. II, p.87) referred it to Pinnularia parva
as a variety, and this is no doubt correct. The species
P. parva has as a rule the short marginal striæ uninter-
rupted all the way round, but occasionally there occur
forms having an interruption in the middle either on
one or both sides. Var. Lagerstedtii has likewise as a
rule no interruption of the striæ. The specimens found
on the Vestmannaeyjar had, however, all such a trans-
apical fascia, and I have therefore thought it right to
term them f. interrupta. The largest specimens showed
transition to the typical P. parva, their apices being
slightly capitate (Fig. 28 a). Within the f. interrupla may
perhaps also be included a »fraglich« form (A. Schm.
Atl. 1. c.). On measuring the figure I find the following
dimensions: L. 25 /u, br. 6 fi, str. 10 in 10/< P. parva
var. Lagerstedtii shows the following range of dimensions:
L. 25—35 fi, br. 5—8,8/<, str. 8—10 in 10 fi. It will thus
be seen that the form in A. Schmidt Atl. shows excellent correspondence
of dimensions with this variety. Hustedt has a figure representing a
form which he calls P. intermedia (1924, Taf. 21, fig. 10), but which cer-
tainly cannot belong to this species, but must be called P. parva v. Lager-
Fig 28.
Piniiularia
parva (Greg.) Cl.
var. Laijerstedlii
Cl. f. interrupta
n f.
(X 1200).
27