192 - On Coral Reefs and Islands. 
The present area is not far from 4,500 square miles. 
The whole Feejee Group, exclusive of coral islets, includes an 
area of about 5,500 square miles of dry land; while, at the period 
when the coral commenced to grow, there was, at least, as the 
facts show, 15,000 square miles of land, or nearly three times the 
present-extent of surface. 
B. Lagoons of Atolls.—We pass from these remarks on the 
channels and seas within barrier reefs, to the consideration of the 
seas or lagoons of coral atolls. The inference, has probably been 
€ manner in which a farther subsidence results in producing 
the atoll, may be illustrated by fig, 5, p. 189, Viewing V, as the 
water line, the land is entirely submerged ; the barrier, b/’”, 6s 
1a Ae angular reef, enclosing a broad area of waters, ora lagoon, 
ee blance, when 
: resem Taey 
pror spe i Hj I ond -P Meneribes, those 
ee encircle islands of moderate size, by ealling them atolls, with high lands 
isi expanse.—Darwin, op. cit.,p.41. 
4 subject is discussed in the chapter ni the author’ i eport, om 
nt This apter, on the author's Geological Report 
the valleys of the Pacific islands, See also this Journal, [2], eae ; 
