474 THE INHABITANTS OF THE SEA. 
Tahiti, so justly named “the queen of islands.” But the 
encircling reefs are often at a much greater distance from the 
shore. Thus in New Caledonia they extend no less than 140 
miles beyond the island. 
As an example of barrier-reefs, I shall cite that which fronts 
the north-east coast of Australia. It is described by Flinders as 
having a length of nearly a thousand miles, and as running 
parallel to the shore at a distance of between twenty and thirty 
miles from it, and in some parts even of fifty and seventy. The 
ereat arm of the sea thus inclosed, has a usual depth of between 
ten and twenty fathoms. This probably is both the grandest 
and most extraordinary reef now existing in any part of the 
world. 
Stone Corals. 
The atolls, or lagoon-islands, are numerously scattered over 
the face of the tropical ocean. The Marshali and Caroline 
islands, the Paumotic group, the Maldives and Lacadives, and 
many other groups or solitary islets of the Pacific or Indian 
Ocean, are entirely built up of coral; every single atom, from 
the smallest particle to large fragments of rock, bearing the 
stamp of having been subjected to the power of organic ar- 
rangement. A narrow rim of coral-reef, generally but a few 
hundred yards wide, stretches around the enclosed waters. 
When a lagoon-island is first seen from the deck of a vessel, only 
aseries of dark points is descried just above the horizon. Shortly 
after, the points enlarge into the plumed tops of cocoa-nut trees, 
