The Botany of Iceland - 01.12.1928, Side 84

408
JOHS. BOYE PETERSEN
stedtii. This variety is recorded to have been found by 0strup in 13
samples from fresh water in Iceland, and is perhaps commonest in
water, but as already stated, Lagerstedt found it on »earth and mos-
ses« (1. c.), while Hustedt found it on Hypnum mounds (1. c. p. 569).
Pinnularia parva (Greg.) Cl. var. minuta 0str. 0strup 1918, p. 36,
Tab. IV, fig. 55. Pinnularia Balfouriana A. Schm. Atl. Pl. 313, fig. 29—31.
(non Cleve!) Bristol 1920 jj. 65, text íig. 8, 3—5? Fig. nostra 29.
L. 14—23 fi, br. 4—6 tu, str. 10—12 in 10/í.
Valve linear or slightly lanceolate with rounded
or truncate apices. Striation short, marginal, some-
times uninterrupted all the way round, sometimes
interrupted in the middle either on one or both
sides. Striæ nearly parallel, almost imperceptibly
radiate in the middle and converging at the apices.
Apical area broad, about half as broad as the cell.
E. Icel. 25, 41, L. 61, L. 68, 69, L. 78, 92, 129 —
N. Icel. 133, 137, 218, 252, L. 253 - W. Icel. 297,
327 - S. Icel. 353.
Pinnularia Balfouriana was first published by Cleve (Syn. II, p. 80,
Pl. I, fig. 18) after a manuscript description by Grunow accompanied
by a drawing by the same. The drawing shows a P. nearly elliptical or
oval in form with somewhat shortened striæ, so that the apical area is
comparatively broad. The striæ radiate slightly, most near the apices.
The valve has the following dimensions: L. 8—10 ,m, br. 4 ju, str. 10 in 10 ju,
and the species is classed under Distantes. Hustedt gives a quite similar
figure (1922, p. 101, íig. 10, and 1924, Taf. 21, fig. 9), whereas the speci-
mens figured in A. Schm. Atl. Pl. 313, figs. 29—31 belong to another spe-
cies which can hardly be classed under Distantes but more probably
under Brevislriatœ. This form is almost twice as large as P. Balfouriana,
the striæ are parallel or slightly convergent towards the apices, the
valve is linear or in small specimens sliglitly lanceolate. The apices
are rounded or more frequently almost truncate. This form which is
probably the same that is figured by Miss Bristol (1. c.) is, as far as
I can judge, identical with N.parva var. minuta 0str. I have tried in
vain to prove this quite conclusively by examining 0strup’s prepara-
tions. It is recorded to have occurred in one sample from Hvitá col-
lected by Arth. Feddersen. The latter, however, collected 3 samples
of algæ from Hvitá, and in one sample especially (puddles near Hvitá)
there were several specimens which I should refer to the present variety,
but none which had exactly the dimensions given by 0strup. Hence
I can hardlv have seen the original specimen drawn and measured by
him, nevertheless I do not doubt that it must be referred to the same
variety as the specimens I saw in the preparation, most of which had
no fascia and in which tlie outline was slightly lanceolate1). Since
0strup cites A. Schm. Atlas (1. c.) under P. Balfouriana it may be pre-
') On measuring a specinien 1 found the following dimensions: L. 17/<, br. 4,8/«,
str. 10 in 10/«, consequently it was somewhat hroader than the specimen described
by Ostrup.

Fig. 29. Pinnularia
parva (Greg.) Cl.
var. minuta 0str.
(X 1200).