58 SEA-SHORE LIFE 
with a tough skin. The basket star feeds upon unlucky fishes 
which may seek a retreat within the branches of the trellis, only to 
Fig. 30; BASKET STARFISH. Tortugas, Florida. 

be seized and devoured. 
It is found along our 
North Atlantic coast 
from the eastern end of 
Long Island north- 
ward, and although 
rare in shallow water, 
it isabundant at depths 
of twenty feet or more, 
being especially com- 
mon off Provincetown 
or in Eastport Harbor. 
The Purple Sea Ur- 
chin, (Arbacia pune- 
tulata, Fig. 51), a dark 
brown or brownish-purple sea urchin, is quite common on broken 
rocky bottoms along our coast from Mexico to Cape Cod. The body 
is globular and hemispherical, 
and about one and three-quar- 
ters inches in diameter. It is 
protected by a skeleton formed 
within the skin, and composed 
for the most part of six-sided 
calcareous plates arranged in 
an orderly manner. The body 
is covered with conical spines 
of various lengths up to about 
three-quarters of aninch. These 
are found chiefly in five broad 
radii regularly spaced around 
the body, while between these 
spiny areas one sees five nar- 
row spaces almost devoid of 

Fig. 31; PURPLE SEA URCHIN. 
Cold Spring Harbor, Long Island Sound. 
spines. There are five double rows of tube feet provided with ter- 
minal suckers. These arise in the spiny areas and may stretch 
out so as to become longer than the spines themselves. 
At the 
