VOL. III. | Natural History of the Farallones. 149 
This little Porphyra I have found growing only on Zostera and 
Phyllospadix, but it probably grows on other plants, hence the name 
for the order to which these two plants belong, Naiadacee. Some 
small mollusks, in rasping for food on these plants, cause abrasions, 
in which the spores of this Porphyra find a place to adhere and 
grow, so that many of the stems and leaves of these Naiads are lit- 
erally covered with the brownish-purple fronds. It may be found 
at all seasons, wherever these weeds grow, along the whole length 
of our California coast. 
Heretofore it has been distributed as Porphyra vulgaris, but 
without much more reason than our early botanists had for placing 
all seaweed in the genus Fucus. 
It adheres closely to paper, and retains its natural color pretty 
well when mounted. 
P. NEREocystTIs Anderson, n. sp.*—Fronds 3 to 20 inches long 
and 1 to 3 inches broad, very thin and ribbon-like, with nearly even’ 
or slightly crinkled edges and a somewhat pointed or oval tip; stipes 
very short or entirely wanting; frond often divided, sending long sec- 
tions from either side; color brownish-purple, often changing to a 
bright carmine-purple, with a soft, glossy surface. Cells smaller, but 
otherwise hardly different from P. vulgaris Harv. 
This large and beautiful Porphyra is most frequently found, on 
this Coast, growing on the long stems of the Nereocystis, although 
not always confined to that plant. Frequently it is torn loose and 
comes ashore in the drift, but mostly in fragments. It also has 
been considered only a form of P. vadgaris. But its structure, color 
and form surely entitle it to a specific place. 
It adheres well to paper, and is seldom found until past midsum- 
mer, when the long stems of Nereocystis are well grown. 
Ceramium diaphanum Roth. 
Centroceras clavulatum Ag. 
Microcladia Coulteri Harv. 
M. borealis Rupr. 
Ptilota asplenoides Ag. 
P. plumosa Ag.=P. filicina. 
P. densa Ag. 
* This was published — name only — in ‘List of California Marine Algz,” Zoe, 
i, 221. 
