^P. sharreri.^ This species occurs, in deep water, off the coast of North Carolina and thence southward to the West Indies. The shell is light greenish-pink. The spines are white, with brownish-pink at the base, pointed, three and a half inches long, and surrounded at the base with small, flat, triangular, secondary spines. (Plate LVII.) FAMILY ~ARBACIADÆ~ GENUS ^Arbacia^ ^A. punctulata.^ A small species found in shallow water on shelly and gravelly bottoms from Massachusetts to Mexico, and common in Long Island Sound. The shell is about one inch in diameter; the spines are rather thick and one half to three quarters of an inch long. The color varies from deep violet—almost black—to straw-color, and the spines are tipped with brown. The South Carolina species are usually brick-red in the bare interambulacral spaces, with darker sutures, and spines tipped with same color. The animal walks by means of its spines, with a tilting motion, and advances quite rapidly. (Plate LVII.) GENUS ^Cœlopleurus^ ^C. floridanus.^ This beautiful sea-urchin is taken on the Florida reefs. The very brittle spines are one to four inches long, and are banded with carmine and white. The shell has zones of light chocolate-color alternating with orange and yellow. FAMILY ~DIADEMATIDÆ~ GENUS ^Diadema^ ^D. setosum.^ Spines very brittle, and from one to two and a half inches long; jet-black. Found on the Florida reefs. (Plate LVII.) [Illustration: PLATE LVI. Pedicellariæ of sea-urchins. Spines of sea-urchins.] [Illustration: PLATE LVII. Porocidaris sharreri. Dorocidaris Blakei. Arbacia punctulata. Diadema setosum. Strongylocentrotus franciscanus.] FAMILY ~ECHINOMETRIDÆ~ In this family the ambulacral plates have several pairs of pores. GENUS ^Echinometra^ ^E. subangularis.^ This species, which ranges from South Carolina to Brazil, and is also found in Bermuda, is common on mud-flats and is easily distinguished by its oblong or elliptical shape. Its shell is about three inches long in its widest portion. The spines are one half of an inch to one inch long, thick at the base and tapering to a point. The color is dark purplish-green to deep violet—almost black. GENUS ^Strongylocentrotus^