146 A, E. Verrill—The Bermuda Islands; Geology. 
Among them are S. roseola (fig. 39), S. inharens, S. acanthia, and 
C. rotifera. All of these swallow the mud in bulk, picking it up 
with their oral tentacles, which they use like hands while feeding. 
Some of the sea-urchins which live on these bottoms have the 
same habit of feeding on mud and sand in bulk, while others select 
with more care the small living mollusks. The most important of 
these is Toxopneustes variegutus (fig. 40), a round species, 2 to 4 
inches in diameter, thickly covered with dark purple, violet, or 
brown spines. it is everywhere abundant on the muddy and sandy 
bottoms, often associated with the large Stichopus, feeding in the 
Figure 40.—Toxopneustes variegatus, 24 natural size. Phot. by A. H. Verrill. 
same way. A larger but much less common species, Zipponoé escu- 
lenta, has the same habit. Its spines are shorter and nearly white. 
In certain localities a flat “cake-urchin ” or “sand-dollar,” with 
six perforations (Melitta sexforis), is abundant and feeds on the sand. 
A large starfish, with five long flat rays, is common in some places, 
living under the surface of the sand. It is remarkable for the 
rapidity with which it can glide along, using its numerous large 
ambulacral feet as paddles or oars for swimming or gliding, while 
concealed just under the loose sand. It feeds on small mollusks. 
This is the Zwidia clathrata, common also on the Carolina coasts. A 
very common ophiuroid ( Ophionereis reticulata), with long slender 
arms and a pale yellowish body, reticulated with brown lines, also 
lives in the sand and under stones. 
