DISTRIBUTION OF REEFS. 141 
B. Clarke as an elevated coral island, with fringing reefs; and it 
appears also from the remarks of this writer, that the other islets of 
what is called the Loyalty Group, are of the same kind. Lafu, the 
largest of the number, is about ninety miles in circumference.* 
South of New Caledonia lies Norfolk Island, in latitude 29° S., 
about which there is said to be some coral which is occasionally 
thrown on the beach, but no reefs. 
Between Australia and New Caledonia the islands are all of coral. 
The New Holland reef extends from Torres Straits to the east cape 
in latitude 24° S., a distance of 1000 nautical miles, though much 
interrupted along its course. It has been shown how this broken 
character results during a subsidence, owing to a change in the ab- 
ruptness of the land successively becoming the coast line, and also to 
the variations in the currents, retarding the growth in some places 
and aiding it in others. ‘These causes might make a broken reef 
that was originally continuous: yet we have no reason to believe 
that the reef ever was continuous. It will be found, as we proceed, 
that long reefs on the shores of continents are not common. In this 
case the zoophytes are not exposed to the destructive agents usual 
on such shores, as the land is in a dry climate, the shores are mostly 
rocky, and there are no streams of any extent emptying into the ocean. 
The east cape is the southern limit, because here the tropical current, 
owing to the direction of the coast above, trends off to the eastward of 
south, away from the land, while a polar current follows up the shores 
from the south as far as this cape. South of this cape there are only 
a few scattered species of coral zoophytes. 
The Louisiade Group is described as a region of extensive reefs. 
The Salomon Islands, as far as ascertained, are but sparingly fringed, 
excepting the two western, which are said to have large reefs. The 
peculiar character of these lands is too imperfectly known to allow of 
our deducing the cause of so restricted reefs. Off to the north of the 
Salomon Islands, there are several atolls of considerable size. New 
Ireland, according to D’Urville, has distant reefs on part of its shores. 
The Admiralty Islands, farther west, are enclosed by barrier reefs ; 
and beyond this group there are a few lagoon islands. 
The north side of New Guinea is mostly without coral. There are 
several islands off this coast, which are conical volcanic summits, and 
* Quarterly Journal of the Geological Society, No. 9, p. 61. 
36 
