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588 University of California Publications in Botany [Vol.8
The type and only species mentioned by Greville is D. foenicu-
laceus. The type locality is "Mona Island" (Isle of Man) (cf.
Dillenius, 1741, p. 16).
Key to the Species
1. Fronds relatively small and delicate, with opposite branching. .1. D. tenuis (p. 588)
1. Fronds more robust, chiefly with alternate branching 2
2. Fronds with slender, attenuated branches 3
2. Fronds with fewer, shorter, thicker, blunt branches
4. D. hippuroides (p. 589)
3. Hispid with slender, short ultimate branchlets 2. D. hispidus (p. 588)
3. Not as above 3. D. foeniculaceus (p. 589)
1. Dictyosiphon tenuis S. and G.
Fronds very fragile and flaccid throughout, 5-10 cm. long, with
main axis percurrent and 225-250//. diam. ; branches opposite, of 3-4
orders, flagelliform ; ultimate ramuli blunt, 40-50//. diam. ; sporangia
scattered, completely submerged in the cortical tissue.
Golofin Bay, Alaska.
Setchell and Gardner, Phyc. Cont., VII, 1924, p. 10. Dictyosiphon
foeniculaceus f. americanus Setchell and Gardner, Alg. N.W. Amer.,
1903, p. 248 (not of Collins).
We have but a few specimens of this species upon which to base
the diagnosis. They were collected by Mr. R. C. McGregor in 1900.
The species is based principally upon the delicate character of the
fronds, the main axis being only about a quarter of a millimeter in
diameter, and upon the prevailing opposite branching, alternate
branching prevailing in the other species. Our plant is much more
slender than the plants referred by Collins to his f. americanus of
D. foeniculaceus which also lacks the regularly opposite branching.
2. Dictyosiphon hispidus Kjellm.
Fronds delicate and flaccid, freely branched on all sides into several
relatively long, primary, flagelliform branches, these in turn irregu-
larly branched, all clothed with numerous, short, subulate or cylin-
drical, ultimate ramuli, tubular below, solid above ; olive brown in
color, darker on drying.
Growing on Chordaria in the lower littoral belt. Orca, Alaska.
Kjellman, Algenveg. Murm. Meer., 1877, p. 47, Spets. Thall. II,
1877a, p. 39, pi. 2, fig. 1. Dictyosiphon foeniculaceus Setchell and
Gardner, Alg. N.W. Amer., 1903, p. 248 (in part).