222 MARINE INVERTEBRATES 



FAMILY CIDAEIDJE 

 GENUS Cidaris 



C. tribuloides. Similar to Poroddaris sharreri, but with thicker and 

 stouter spines. Found from South Carolina to Brazil. 



GENUS Dorocidaris 



D. papillota. A deep-water species which occurs off Chesapeake 

 Bay and southward. It has slender spines with distinct longitudinal 

 rows of serrations, and the spines are grouped in rosette-like forms over 

 the small spherical body. 



D. Blakei. This species is very peculiar in having broad, fan-shaped 

 spines ; vermilion in color. Found in deep water in the Bahamas and 

 West Indies. (Plate LVII.) 



GENUS Poroddaris 



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 ABBACIADJE 

 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 Ccelopleurus 



C.floridamis. 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 DIADEMATID.E 

 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.) 



