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1925] Setchell-Gardner: Melanopliyceae 653
except along: the thickened margins of the old fronds where it is
double ; cortex of a single layer of colored cells, except in older, thick-
ened margins where there are two layers, arranged in longitudinal
parallel series ; oogonia, antheridia, and tetrasporangia all growing on
different individuals ; oogonia scattered in small sori ; antheridia and
tetrasporangia in oval or oblong sori; reproductive cells on both
surfaces of the frond.
fornia.
Growing on boulders in the lower littoral belt. Southern Cali-
Setchell and Gardner, Phyc. Cont. VII, 1924, p. 12. Dilophus
fiabcllatus Collins, in Collins, Holden and Setchell, Phyc. Bor.-Amer.
( Exsicc. ) , no. 834. Glossophora Kunthii Tilden, Amer. Alg. ( Exsicc. )
no. 334. Dictyota dichotoma Tilden, Amer. Alg., no. 335 (not Lamour.).
This seems to be a distinct species, thus far confined to southern
California, but with unattached specimens collected at Monterey, Cali-
fornia, and Tracyton, Washington, probably sporadic or transported
to the latter. The species has the least doubling of the marginal cells
of any in our territory and is closely related to D. Binghamiae. It is
thinner, lighter colored, more pseudodichotomous, with the uppermost
almost pinnately arranged lobes short and bent. It is not difficult to
separate the two species when in company, either living or in her-
barium specimens, but we do find it difficult to express definitely the
exact points of distinction between them.
3. Dictyota Johnstonii S. and G.
Fronds 12-16 cm. high, 5-8 mm. wide, 125-135/* thick, composed
of a single layer of large medullary cells surrounded by a single sur-
face layer of small cells except in the lower part, along the margin the
medullary and surface cells becoming doubled, slightly stupose at the
base, pinnate, dichotomously branched, angles acute to somewhat
rounded, branches strict, margins smooth, color dark brown, black on
drying ;
oogonia aggregated into elliptical or elongated areas, 115-125/*
long, 80-90/* wide; tetrasporangia and antheridia unknown.
Growing on rocks in the upper sublittoral belt. San Marcos Island,
Gulf of California.
Setchell and Gardner, Mar. Alg. Gulf Calif., 1924. p. 730, pi. 18,
figs. 54-56, and plate 39.
Dictyota Johnstonii appears to belong to the subgenus or section
of the genus, Strigocarpus J. Agardh (Anal. Algol. Cont. I, 1894.
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