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1925] Setckell-Gardner: Melanophyceae 459
in the center, gradually diminishing toward the periphery, mostly
sessile, some on 1-3-eelled pedicels, 80-10G> high, 6-6. 5/t diam. ; loculi
uniseriate.
Growing on the blades of Costaria costata, Laminaria SincJairii
and Alceria marginatu. Central California (Moss Beach, San Mateo
County, and Fort Point in San Francisco).
Setchell and Gardner, Phyc. Cont. II, 1922, p. 339, pi. 33, figs. 4, 5.
Forma uniforme differs from the species as described and figured
by Sauvageau (1898, pp. 77-82, repr., figs. 14 A-F) in having no hair
filaments, in having no branched gametangia, in having "ascocysts,"
and in having slightly different dimensions.
There are some differences in the size of the plants we have found
growing on different hosts in central California. The plants chosen
as the type of the form grew on the blades of Alaria marginata at
Fort Point, San Francisco. Very generally, this species of Alaria has
delicate grooves obliquely radiating from the midrib to the margin.
The presence of these grooves is often accentuated by the growth of this
minute Myrionema, usually so numerous as to be confluent, so that the
individuals cannot be detected except by microscopic examination.
4. Myrionema corunnae f. angulatum S. and G.
Fronds forming microscopic cushions, irregular in outline, among
creeping filaments regularly radiating
other small algae on the host ;
when undisturbed ; erect filaments unbranched, densely crowded,
120-140/a long; true hairs absent; cells of creeping filaments 4-4.5/t
diam., mostly quadrate; cells of erect filaments cylindrical, 4-4.5//.
diam., 1.5-3 times as long; zoosporangia and "ascocysts" unknown;
gametangia cylindrical, slightly attenuated at the apices, terminal on
6-10-celled pedicels, 35-45/* (up to 6Gy) long, 4-6.5/x broad, many
partitions of the loculi oblique.
'
Growing on the cysts of Egregia Menziesii. Cast ashore near the
' Cliff House, '
' San Francisco, California.
Setchell and Gardner, Phyc. Cont. II, 1922, p. 340, pi. 33, figs. 6, 7.
This form is to be distinguished from the species as described by
Sauvageau (1898, pp. 77-82, repr.) by the absence of hairs, the
presence of sterile erect filaments, the gametangia mostly on longer
pedicels and by the very small size of the loculi, often produced by
perpendicular and slanting walls. In part, the gametangia seem pluri-
seriate, caused by the division of some of the original cells into small,
angular loculi.