respect to the prevalent winds and action of the waves.--Destruction of
islets.--Connection in the position and submarine foundation of distinct
atolls.--The apparent disseverment of large atolls.--The Great Chagos
Bank.--Its submerged condition and extraordinary structure.


CHAPTER II.--BARRIER REEFS.
Closely resemble in general form and structure atoll-reefs.--Width and
depth of the lagoon-channels.--Breaches through the reef in front of
valleys, and generally on the leeward side.--Checks to the filling up of
the lagoon-channels.--Size and constitution of the encircled islands.--
Number of islands within the same reef.--Barrier-reefs of New Caledonia and
Australia.--Position of the reef relative to the slope of the adjoining
land.--Probable great thickness of barrier-reefs.


CHAPTER III.--FRINGING OR SHORE-REEFS.
Reefs of Mauritius.--Shallow channel within the reef.--Its slow filling
up.--Currents of water formed within it.--Upraised reefs.--Narrow
fringing-reefs in deep seas.--Reefs on the coast of E. Africa and of
Brazil.--Fringing-reefs in very shallow seas, round banks of sediment and
on worn-down islands.--Fringing-reefs affected by currents of the sea.
--Coral coating the bottom of the sea, but not forming reefs.


CHAPTER IV.--ON THE DISTRIBUTION AND GROWTH OF CORAL-REEFS.

SECTION 4.I.--ON THE DISTRIBUTION OF CORAL-REEFS, AND ON THE CONDITIONS
FAVOURABLE TO THEIR INCREASE.