160 CORALS AND CORAL ISLANDS. 
tion between the Friendly Islanders and the Feejees has long 
been kept up by means of these large rudely-rigged sail-canoes. 
Instead of a rock-bound coast, harborless and thinly hab- 
itable, like St. Helena, in the tropics, and nearly all extra- 
tropical islands, the shores of these reef-bound lands are bloom- 
ing to the very edge, and wide plains are spread out with 
bread fruit and other tropical productions. Harbors, safe for 
scores of vessels, are also opened by the same means; and 
some islands number a dozen, when the unprotected shores 
would hardly have afforded a single good anchorage. Jukes 
remarks that the sea within the great Australian barrier is 
‘one great natural harbor;” and this harbor is as long as 
from the extremity of Florida to Newfoundland. 
Coral-reefs are sometimes viewed as only traps to sur- 
prise and wreck the unwary mariner; but whoever has vis- 
ited the dreary prison-house, St. Helena, will have some appre- 
ciation of the benefits derived from the growing zoéphytes. 
But in addition to these general, benefits, there are also 
contributions from the larger reef regions to the commerce 
of the world. Besides pearls, there is the biche de mar 
(called also, béche de mer, sea-ginseng, and in China, tripang), 
thousands of hundred-weight of which annually enter the 
Chinese market from the reef-regions of the Kast Indies, Aus- 
tralia, and the seas to the north, including the Feejee Archi- 
pelago. This favorite material for Chinese dishes, either stews 
or soups, etc, is dred holothuria—large slug-like animals, 
called often sea slugs, and also sea cucumbers, from their form 
in the contracted state. They are not slugs, but are most 
nearly related to the echinus, though having a thick flexible 
skin, while the echinus has for its exterior a firm shell, armed 
about with spines. The largest are only nine or ten inches 
long when contracted ; but they lengthen out sometimes to 
