Variety ^formosa^. Filaments soft and finer than in /P. urceolata/; branches long and flexuous; articulations five to ten times longer than broad; color bright red. It grows in tufts sometimes a foot long, and is found only in the spring. [Illustration: PLATE XXVII. Polysiphonia nigrescens. Polysiphonia fibrillosa. Polysiphonia violacea. Polysiphonia Woodii.] [Illustration: PLATE XXVIII. Laurencia pinnatifida. Dasya elegans. Dasya plumosa. Dasya plumosa, magnified.] ^P. variegata.^ Fronds four to ten inches high; filaments thick as a bristle below, and branched in a forking manner to the very top; divided at long intervals below, at the top becoming of hair-like fineness [pg089] and dividing rapidly, forming a densely tufted mass, which collapses when taken from the water; color purple-brown; when mounted, silky in appearance; filaments banded; siphons six in number. It forms purple tufts on woodwork and on eel-grass from Cape Cod southward. ^P. Woodii.^ Fronds four to six inches high; branches flat, long, wide-spreading, emanating from the edges in one plane; younger branches show articulations; ultimate branchlets inclined to curve inward; color light brown. Found on the California coast. (Plate XXVII.) GENUS ^Laurencia^ ^L. pinnatifida.^ Frond flat, thick, leathery; main stem with opposite, or alternate, branches of about the same size and character as itself; all pinnatifid, or cut on the edges into branchlets, some of which are again divided; color bright purple, often unevenly faded. It is found on the Pacific coast. (Plate XXVIII.) GENUS ^Dasya^ Chenille-weed. ^D. elegans.^ Fronds from six inches to three yards long; main stem and branches cylindrical, and all densely clothed with a fine, hair-like fringe, which gives the plant the appearance of chenille; cystocarps on stalks along the branches; color pink or lake-red. Out of water it seems like a mass of purple jelly. It is found at or just below low-water mark from Cape Cod southward, and is very plentiful in New York Bay. (Plate XXVIII.) ^D. plumosa.^ A species found on the California coast. The fringe covering the stems consists of minute leaflets instead of hairs, as in /D. elegans/. (Plate XXVIII.) GENUS ^Bostrychia^ ^B. rivularis.^ Fronds one inch high; color dark purple; branches fine and irregularly bent. It grows where the water is not very salt, and is found in patches on submerged logs near New York. Common from Charleston, South Carolina, southward. (Plate XXIX.) GENUS ^Rhodomela^