^P. latifolia.^ Frond pale green, four to twelve inches long, one inch to five inches wide, leaf-like, and tapering suddenly to a short stalk; much [pg066] waved on margin; substance soft and thin; dotted with spores. In the young plants fine hairs emerge from the dots, but disappear later, and the fronds become darker and more rigid. Found in summer on rocks and on other algæ on the Long Island and New England coasts. ^P. tenuissima.^ Fronds smaller and more slender than in /P. latifolia/; thin and delicate. Found on eel-grass and /Chorda filum/. ^P. plantaginea.^ Fronds dark brown, leathery, leaf-like, blunt or wedge-shaped on top; dense clusters of hairs on the dots; six to twelve inches long, one inch to one and a half inches wide. GENUS ^Asperococcus^ This genus differs from /Punctaria/ in having a tubular instead of a flat frond. (Plate IX.) ^A. echinatus.^ Resembles /Enteromorpha/ in being tubular; compressed or inflated; obtuse at the apex; attenuated at the base. It differs from /Enteromorpha/ in being olive in color, and in being covered with small oblong dots of darker shade. When the plant is young the dots are hairy. It grows in clusters, two to eighteen inches long, one half of an inch to one inch wide. Common along the New England coast. GENUS ^Phyllitis^ ^P. fascia.^ Fronds light olive-green, leaf-like, three to six inches long, one fourth to one half of an inch wide; margin entire, slightly waved; contracted at base to short stalk; attached by disk. This species grows in bunches on rocks and stones at low-water mark, and is very common everywhere. (Plate X.) ORDER =DESMARESTIACEÆ= (/Named for M. Desmarest, a French naturalist/) GENUS ^Desmarestia^ ^D. viridis.^ Filaments cylindrical, about as thick as a bristle; branches opposite, in pairs, at intervals on the main stem. The branches branch again and continue to be disposed in the same manner. All are long and ultimately become very fine. The color is olive-green, becoming verdigris-green when exposed to the air for a short time or placed in fresh water. The species grows in deep tide-pools and below low-water mark, forming fine, feathery plumes, often a yard long, which give submerged rocks the appearance of a luxuriant garden. (Plate X.) [Illustration: PLATE IX. Ectocarpus littoralis. Ectocarpus viridis. Cladostephus verticillatus. Asperococcus bullosus.] [Illustration: PLATE X. Phyllitis fascia. Desmarestia viridis. Desmarestia aculeata. Desmarestia ligulata.]