166 THE WORLD OF THE SEA. 
teeth, and remove the dédris as it is formed by their spines. 
MM. Caillaud, Robert and Lory, have published some most inter- 
esting information upon this boring power of the echinus. It 
seems that even the young urchins, almost as soon as they are 
developed, commence the work, and form for themselves a hole 
fitted to their size. Poor little quarrymen, who pass a great part 
of their lives in working granite with their teeth! 
When an urchin is cast up upon the shore, and left by the 
water, it buries itself in the sand, which it excavates with its 
URCHINS IN A ROCK. 
spiny appendages. The place where it is hid is easily recognised 
by the hole which it has left in its entombment. The fishermen 
pretend to foretell storms according to the depth to which the sea- 
hedgehogs bury themselves. 
Linneus has enumerated only seventeen species of echini; 
Gmelin, 107; but now many hundreds are known, and this 
group of animals has become the type of an entire class—the 
Echinodermata. 
In many countries the sea-urchins are eaten raw; their flesh is 
yellow, and of a very agreeable taste. Those which are esteemed 
in Provence, are—the edzble, the granulous,* and the “vidt A 
member of this last species is also in request at Naples, where 
the melon urchin} is served at table as a regular dish. 
* Toxopneustes granularis, ¥ Zoxopneustes lividus. t LZchinus melo. 
