^C. Ellisii.^ Zoarium erect, with fibrous base, leaf-like, branches in a forking manner; branches straight, stiff, narrow, spreading; cells arranged in rows of three, adherent throughout; long bristles emanate from near base of many cells; egg-capsules globular, smooth, pearly. Common from Cape Cod northward in deep water. (Plate L.) GENUS ^Bugula^ [Illustration: 1, /Bugula turrita/, enlarged; 2, the same, a branchlet, highly magnified; 3, the same, a branchlet, bearing ovicells.] ^B. turrita.^ This is a very abundant species, found everywhere along the coast from Maine to North Carolina. Large quantities of it are [pg196] sometimes thrown upon the beach by storms. It grows in erect tufts, sometimes a foot long, and is much branched; the branches grow around the stem in a spiral manner, forming dense clusters. The lower part of the stem is often naked (having lost the branches) and bright orange in color, while the tufts of branches at the top are pearly-white or yellowish. The cells are long, with a long, pointed spine on the upper outer angle. Like all species of /Bugula/, it has bird-head appendages, which can be seen under a powerful glass. (Plate L.) ^B. Murrayana.^ Clusters of broad, thin, flexible fronds, one to two inches high, attached by a slender base and spreading in entangled masses; fronds wedge-shaped, flat, dividing in a forking manner; outer cells have bristle-like filaments, which constantly beat the water; all cells have avicularia, or bird-head appendages. (Plate L.) ^B. flabellata.^ Fan-shaped fronds of flat branches, divided in a forking manner; the cells are arranged in four or five longitudinal rows, are oblong, with a spine at each side of the circular aperture, and are capped with pearl-like ovicells. This species, like others of the genus, bears the very singular structures known as avicularia, or bird-head appendages. They show, under a strong glass, a hooked beak, like that of the hawk or parrot. These beaks are attached by flexible stems and are provided internally with powerful muscles by which they are constantly opened and closed; the beak can bite with considerable force. In this species they are attached to the sides of the cells. (Plate L.) GENUS ^Flustra^ ^F. membranacea.^ This species forms gauze-like incrustations on the fronds of seaweeds, and is common on /Fucus/ and /Laminaria/, spreading irregularly over several inches of space. The cells are oblong, quadrangular, with a blunt, hollow spine at each angle. Many specimens have simple horny tubes, closed on top, rising from some of the cells to the height of half an inch. (Plate LI.) [Illustration: PLATE LI. Flustra foliacea. 1, 2, Cellepora pumicosa, natural size; 3, C. pumicosa, magnified; 4, C. ramulosa. 1, Flustra membranacea; 2, 3, F. membranacea, magnified. Vesicularia dichotoma.] GENUS ^Membranipora^