38 CORAL FORMATIONS. 
cemented: other portions are a finer coral breccia, or conglomerate : 
and still others, more common, are solid white limestone, as impalpable 
and homogeneous in texture as the secondary limestones of our conti- 
nents, and usually much harder. It is rare to meet with any corals in 
this reef-rock retaining the original position of growth. It is at once 
apparent that the rock consists of the debris of the coral fields, con- 
solidated by a calcareous cement; and the great abundance of the 
finer variety of rock indicates that much of it has originated from 
coral sand or mud. Wherever broken, it is found to present the same 
character as here described, a texture indicating a detritus origin. 
This reef-rock is formed in the midst of the waves; and we shall here- 
after show that to this fact it owes many of its peculiarities. Besides 
corals, the shells of the seas contribute to it, and it sometimes contains 
them as fossils, along with bones of fish, exuviee of crabs, spines and 
fragments of echini, and other remains of organic life inhabiting reef- 
grounds. 
Inner reefs.—In the still waters of the inner channels or lagoons, 
when of large extent, we find corals growing in their greatest per- 
fection, and the richest views are presented to the explorer of coral 
scenery. ‘There are many regions—in the Feejees, examples are 
common—where a remote barrier encloses as pure a sea as the ocean 
beyond; and the greatest agitation is only such as the wind may 
excite on a narrow lake or channel. ‘This condition gives rise to some 
important peculiarities of structure in the inner reefs. 
In the general appearance of the surface, however, they much 
resemble the outer reefs. ‘hey are nearly flat, and though mostly 
bare of life, and much covered with coral sand, there are seldom any 
large accumulations of coral debris. ‘The margin is generally less 
abrupt; yet there is every variety, from the gradually sloping bed of 
corals to the bluff declivity with its clinging clumps. Over the sur- 
face there are many portions still under water at the lowest tides; and 
here, (as well as upon the outer banks,) fine fishing sport is afforded 
the natives, who wade out at the ebb tide with spears, pronged sticks, 
and nets, to supply themselves with food. ‘The lover of the marvellous 
may find abundant gratification by joining in such a ramble; among 
coral plants and flowers, with fishes of fantastic colours, starfish, 
echini, and myriads of other beings which science alone has named, 
fit inhabitants of a coral world, there is on every side occasion for 
surprise and admiration. 
Between the larger reefs, which spread a broad surface at the water’s 
