’ 
| i 53 s On Coral Reefs and Islands. 363 
The rock of the reef, wherever broken, exhibits a compact tex- 
ture. In some parts it consists of coral fragments of quite large 
size firmly cemented: other portions are a finer coral’ breccia, or 
| conglomerate: and still others, more common, are solid white. 
limestones, as impalpable aud homogeneous in texture as the sec- 
ondary limestone of our continents, 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 
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ganic life inhabiting reef-grounds. 
nner ree/s.—In the still waters of the inner channels or la- 
goons, when of large extent, we find corals growing in their great- 
_ est perfection, and the richest views are presented to the explorer 
 ofcoral scenery. There are many regions—in the Feejes, exam- 
ples are common—where a remote barrier encloses as pure a sea 
asthe ocean beyond; and the greatest agitation Is only such as 
the wind may excite on a narrow lake or channel. This condi- 
inner reefs, : 
iy In the general appearance of the surface, however, they much 
resemble the outer reefs. They are nearly flat, and though mostly 
bare of life, and much covered with coral sand, there are seldom 
4 _ any large accumulations of coral debris. ‘The margin 1s generally 
less abrupt; yet there is every variety, from the gradually sloping 
bed of corals to the bluff declivity with its clinging clumps. In dif- 
ls throughout. ey are ele 
h at times but a few yards in breadth, there is often along- 
