^A. ramosum.^ Twelve to fifteen inches high; much branched; branches smooth, cylindrical, one third of an inch in diameter, usually crooked; branches in a forking manner; color rusty-brown. Abundant in shallow water, attached to rocks, from New Jersey to Cape Cod. ^A. hirsutum.^ A species common on seaweeds, sometimes completely covering them, forming dirty, straw-colored, thick, cartilaginous crusts covered with numerous conical papillæ. These are the cells, or zoœcia; they are surrounded with spines. Circular yellow spots occur over the surface, which are clusters of eggs. A good pocket-lens will show the cells, laid in beautiful order, and perhaps the extended tentacles. Found from Long Island Sound northward. [pg198] ^A. hispidum.^ One of the most common species found incrusting the fronds of /Ascophyllum/ at low-water mark. It forms fleshy, brown, soft crusts of moderate thickness, and has spines scattered over the otherwise smooth and glistening surface. The cells are inconspicuous, and each one has five long rigid bristles. Habitat, Long Island Sound to Greenland. ^A. parasiticum.^ It forms thin, earthy crusts on algæ and hydroids. The surface is porous; the cells are distant and arranged irregularly, and seem as if composed of sand cemented with mud. GENUS ^Vesicularia^ ^V. dichotoma^ (^Valkeria pustulosa^). This species grows in clusters of crowded slender stems, which branch in a forking manner, the branches dividing in different planes, making a tree-like form one to three inches high. At the points where the branches divide is a dark, opaque substance, and at these points also the cells are crowded in clusters of spiral rows and are greenish-brown in color. The dark spots are in marked contrast to the white translucent substance of the rest of the stem, giving a spotted aspect to the whole. (Plate LI.) ^V. custata.^ Delicate, thread-like, jointed stems, with slender opposite branches; cells small and elliptical, arranged mostly in clusters. Found creeping like a small dodder-plant over other polyzoans, hydroids, and seaweeds. SUBCLASS =ENTOPROCTA= GENUS ^Pedicellina^ ^P. americana.^ A very small species. Club-like zoœcia rise from slender, white, creeping stems; tentacles roll up instead of retracting into the cups. Found on hydroids, other polyzoans, and algæ. V ECHINODERMATA Phylum =ECHINODERMATA= Classes =ASTEROIDEA= (/Starfishes/) =OPHIUROIDEA= (/Brittle-stars/) =ECHINOIDEA= (/Sea-urchins/) =HOLOTHUROIDEA= (/Sea-cucumbers/) =CRINOIDEA= (/Feather-stars and Sea-lilies/) [pg201] TERMS USED IN DESCRIBING THE STRUCTURE OF ECHINODERMS ^Abo´ral surface^: The side opposite the mouth. ^Ambula´cra^: Tubular feet used in moving. ^Ambulacral zones^: The five areas containing the rows of tube-feet. ^Ampul´læ^: Reservoirs or vesicles at the base of the tube-feet.