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462 University of California Publications in Botani/ [Vol.8
on the other part of the host is a mixture. In height of gametangia
forma simplicissimum approximates to forma seriata Reinke (1889,
p. 46), but has no true hairs so far as we have been able to observe
from the examination of many specimens from different localities. At
times the individuals are very numerous on the host, so much so as to
interfere with each others' growth. In one collection (Gardner,
no. 4651) they are completely confluent over several square inches,
and the outline of the individuals can be detected only by staining
and by microscopic examination.
7. Myrionema foecundum f. subulatum S. and G.
Basal filaments attached by numerous awl-shaped rhizoicls, 2-4
cells long, penetrating between the cells of the host; zoosporangia,
"ascocysts" and true hairs unknown.
Growing on the sporophylls of Nereocystis Luetkeana. Near the
'
' Cliff House, '
' San
Francisco, California.
Setchell and Gardner, Phyc. Cont. II, 1922, p. 337, pi. 33, figs. 1-3.
Forma subulatum is very similar to forma simplicissimum. The
gametangia average slightly larger and are usually more blunt. There
are no so-called "ascocysts" present. The chief distinction is the
presence in this form of numerous awl-shaped rhizoids, found in no
other form of the species, so far as we have been able to ascertain.
8. Myrionema foecundum f. ramulosum S. and G.
Fronds forming small circular cushions, 1-3 mm. diam. ; erect
filaments slightly branched above, 55-65/x long ;
cells of the erect fila-
ments 5.5-6.5/* diam., quadrate, terminal cell frequently 2-3 times
as long; zoosporangia, "ascocysts" and true hairs unknown; all of the
erect filaments transformed into gametangia.
Growing on the pneumatocysts of Nereocystis Luetkeana. Friday
Harbor, San Juan Island, Washington.
Setchell and Gardner, Phyc. Cont. II, 1922, p. 337, pi. 33, fig. 8.
This form of 31. foecundum differs from the other forms of the
species in having secund "proliferations" near the outer ends of
many of the gametangia.