^G. Americana.^ Frond a delicate membrane, rose-red or purplish in color, leaf-shaped, four to eight inches long, one inch to four inches wide, tapering at both ends; margin entire, but much waved; a line of darker color through the center resembles a midrib; masses of spores form dots or specks irregularly over the whole surface; grows from a disk and short slender stem in bunches on shells and stones in deep water. It is found washed ashore from Cape Cod southward, and is luxuriant in New York Bay, where it can be found at any season, but is in perfection in August. (Plate XXIV.) GENUS ^Delesseria^ ^D. sinuosa.^ Delicate, leaf-like membrane, with midrib and veins, much indented and resembling in general outline an oak-leaf; four to eight inches long, two to four inches broad; short stem; color dark red, often flecked with green. It grows in bunches in deep water, and is easily distinguished, since it is the only alga having a midrib and veins, and resembling the leaf of a tree. It is found washed ashore from Cape Cod northward. (Plate XXIV.) ^D. alata^ ("winged"). Frond rises from short stem, which flattens and divides irregularly into many branches and appears like a midrib, all bordered with narrow membrane one eighth of an inch to one inch wide; frond two to four inches long; color light red or pink. It is found on the shore from Cape Cod northward. (Plate XXV.) ^D. Leprieurii.^ Frond one inch to two inches long, very narrow, with delicate midrib, forked, constricted at intervals; branches start from constricted points; thin and delicate; color purple. It is found in tidal rivers near New York, and is common on the southern coast. (Plate XXV.) [Illustration: PLATE XXIII. Champia parvula. Champia parvula, magnified. Plocamium coccineum. Nitophyllum laceratum.] [Illustration: PLATE XXIV. Nitophyllum Ruprechteanum. Nitophyllum punctatum. Grinnellia americana. Delesseria sinuosa.] [Illustration: PLATE XXV. Delesseria alata. Delesseria Leprieurii. Polysiphonia fastigiata (on Ascophyllum). Polysiphonia parasitica.] [Illustration: PLATE XXVI. Polysiphonia dendroidea. Polysiphonia dendroidea, a piece magnified. Polysiphonia Harveyi. Polysiphonia Harveyi, a piece magnified.] SUBORDER ~RHODOMELEÆ~ The genera included in this suborder are easily distinguished when in fruit by the spore-cases, or cystocarps, which appear [pg087] like little balls, either adherent to the branches, or raised on short stalks. It is the largest group, and contains many of the most beautiful of the red algæ. GENUS ^Polysiphonia^ ("/Many tubes/")