A. FE. Verrill—The Bermuda Islands; Coral Reefs. 323 
North Rocks. It adheres firmly to the rocks, in crevices and cavi- 
ties, by means of its sucker-feet. 
Diadema setosum Gray. Long-spined, or black Sea Urchin. Figure 174. 
Puate XXXIV, FicuRE 1. PuatTe XXXVI, FIGURE 1 (12). 
This is one of the largest and most interesting forms. When full 
grown the shell may be 3 inches in diameter and the slender, barbed, 
and very sharp spines may be more than 6 inches long. In life the 
color of the adults is purplish black, but when young the slender 
spines are annulated with purple and white. The spines are effective 
Figure 173.—Chondroclea (or Synapta) vivipara, x2. From colored figure. 
Figure 174.—Diadema setosum, with spines removed, about 4 nat. size. Phot. 
and drawn by A. H. V. 
organs of defence, and are notorious for the painful wounds that 
they inflict when an inexperienced person attempts to capture the 
creature. When touched large numbers of spines are almost 
instantly converged toward the point of contact. The very sharp 
tips are brittle and break off in the wounds. They are hard to 
remove on account of their barbed structure. They also seem to 
convey some poisonous secretion, very irritating to most persons, 
causing much pain and swelling, but the purple discoloration of the 
flesh around the wounds, often very alarming in appearance, is due 
to the absorption of the purple coloring matter of the spines and 
soon passes away. ‘This creature is very active for a sea-urchin, and 
when disturbed usually quickly glides away and conceals itself in 
some nearby cavity beneath the rocks. It is common on the outer 
