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528 University of California Publications in Botany [Vol. 8
Myelophycus intestinale presents a different aspect when young
from that of the older plant. This is seen particularly at the tips
which are long acuminate when young, but blunter and often worn
away in age. The younger plants seem less conspicuously twisted than
the older. Our plant has fewer layers of cells in the intermediate
layer and shorter cortical filaments than the M . caespitosum of Japan.
Myelophycus intestinale f. tenue S. and G.
Plate 40, fig. 50
Fronds densely caespitose, inconspicuously twisted, 1.5-2.5 cm.
high, 0.25-0.75 mm. diam. ; zoosporangia broadly ellipsoidal, 40-45/*
long, 30-35ju broad.
Growing on rocks, usually in shaded localities, and where the spray
dashes against the rocks, along high-tide level. Coos Bay, Oregon, to
central California.
"Myelophycus intestinalis f. tenuis" Setchell and Gardner, in
Gardner, New Pac. Coast Mar. Alg. I, 1917, p. 385.
family 9. STEIAEIACEAE kjellm.
Fronds filiform, solid, more or less branched, trichothallic, mono-
siphonous at first, later usually of two sets of tissues, the inner of
larger, colorless, more or less elongated cells, the outer a single layer
of medium sized cells placed in horizontal rows and having chromato-
phores; unilocular zoosporangia and plurilocular gametangia super-
ficial or projecting beyond the surface in sori of more or less definite
circumscription and usually in transverse rows; with or without
paraphyses.
Kjellman, Handbok I, 1890, p. 53.
It seems best to follow Kjellman and keep the seemingly very
distinct genera, Stictyosiphon, Striaria and their near relatives
separate from the Asperococcaceae and the Scytosiphonaceae and
retain them among the Striariaceae. Both the gametophytes and the
sporophytes are known and are similarly macroscopic, but conditions
are otherwise in the other two families just mentioned. In the
Asperococcaceae there are dissimilarities in size, at least in some
species, between the individuals bearing gametangia and those bear-
ing zoosporangia, although neither is properly microscopic so far as
known. Among the Scytosiphonaceae, only the gametangial form is
known, suggesting that the zoosporangial form may be heteromorphic,