60 SEA-SHORE LIFE 
When young the spines are banded with dark gray and white, 
but they become dark brown or dark purple in the adult urchin. 
The body of the urchin is sprinkled over with glistening blue eyes 
each one of which is provided 
with a number of prismatic 
lenses, a retina and nerves. 
The Sand Dollar, (Hehi- 
narachnius parma, ig. 52), 1s 
found in swarms upon sandy 
bottoms from New Jersey 
northward to the Arctic Ocean 
and the Pacific. It is flat with 
a rounded edge, about three 
inches in diameter, and dense- 
ly covered with short brown 

spines. The mouth is at the 
centre of the under side, 
while the vent is at the mar- 
gin. Radiating outward from the centre of the upper side one 
will see the slightly raised pattern of a five-rayed star, the borders of 
which are outlined by numerous little pores, through which gill-like 
organs project upward. The sand dollar is enabled to glide over 
the bottom through the action of its numerous sucker-like feet. 
When turned over on its back it is unable to right itself, however, 
and thousands are cast ashore by every great storm. An indelible 
ink is prepared from sand dollars by pounding them up in water. 
The Brittle Sea-Cucumber, (Synapta inherens, Mig. 33), lives 
in sand tubes within sandy or muddy beaches from the Carolinas to 
Cape Cod, and is also found on the coasts of Europe. At first sight 
it resembles a worm, but it is an Echinoderm closely related to the 
starfishes and sea urchins. Its body is highly contractile, but when 
extended is about one-eighth of an inch in diameter and more than 
a foot long The creature is translucent with five white lines 
marking the places where muscle bands extend down the body. The 
skin is covered with little white dots that indicate the places occupied 
by minute calcareous anchors which enable the animal to obtain a 
hold when moving. The mouth is at the front end of the long worm- 
like body and is surrounded by twelve feathered tentacles. The coiled 
Fitz. 32; SAND-DOLLAR. 
