29 
No. 128. C. opuntia. Good and Woodw. Very obscure purple, anastomose, 
and very irregularly branched. 
Half an inch to 1J inches long; in rock pools; very rare. I found it on one occasion only in a rock 
pool, at Hurl gate, on the rock, and on Ph. Brodisei, at low-water mark. Its anastomosing properties render 
it necessary to tear it somewhat, in spreading it on paper; summer and autumn. 
Family XIII CBMAMIB2EL J. Ag. 
Rose red, or purple, filiform ; fructification, very like receptacles, containing an¬ 
gular spores; also tetraspores (antheridia ?) attached to branches, or more or less im¬ 
mersed. 
Genus, PTILOTA. Ag. 
Inarticulate, linear, compressed or flat, distichous, the pinnules sometimes arti¬ 
culate ; fructification, fruit roundish, clustered, surrounded by an involucre of short 
ram ul i. 
No. 140. P. plumosa. L. Cartilaginous, secondary branches bi-tripinnate, 
elongate, pinnules opposite ; tetraspores on short pedicils ; fruit pedunculate. 
Very rare in our Bay, and found only floating in small fragments. It is very abundant a few miles east¬ 
ward of New York. 
Genus, FIRMATXJS. 
Dull purple, cartilaginous, solid; fruit round, solitary, not involucrated, sessile 
and immersed ; periphery of closely packed filaments, the centre of lax, anastomosing 
filaments, forming small polygonal cells. 
No. 142. F. nanus . Stout, rigid, cylindrical, or somewhat compressed, many 
times dichotomous, fastigiate, dull purple ; fruit perfectly round, sessile, and also im¬ 
mersed. 
Autumn, at Hurl gate, on Fucus nodosus; half an inch to one inch high. 
No. 143. F. pumilus. Filiform, cylindrical, setaceous, many times dichoto¬ 
mous, axils obtuse, dull purple, approaching a brown ; fructification, spores contained 
in round pericarp, sessile, also perfectly round tetraspores, immersed just beneath the 
surface. 
Summer and autumn, at Hurlgate; 1 to 3 inches high ; on Fucus nodosus and on F. vesiculosus. This 
plant resembles to the eye, some varieties of Gelidium corneum, while F. nanus resembles some dwarf varie¬ 
ties of C. rubrum, but the fruit is clear and decisive. 
Genus, CERAMIUM. Roth. 
Filiform, one tube, articulated; dissepiments opaque and colored, the same color 
and opacity sometimes extends over the whole plant; fruit roundish, subtended by 
short involucre ramuli. 
No. 145. C. rubrum . Huds. Irregularly dichotomous, apices of ramuli hook¬ 
ed inwards, articulations coated, and often obscure, dissepiments constricted, tetra- 
