562 CORAL FORMATIONS. April, 1836. 



remarka1)le degree ; and that certain laws may be inferred 

 from the examination, of far more importance than the 

 mere explanation of the origin of the circular or other kinds 

 of reef. 



If there had been space, I should have made a few gene- 

 ral remarks, before entering into any detail. I may, how- 

 ever, just notice the remarkable absence of the reef-build- 

 ing polypi over certain wide areas within the tropical sea : 

 for instance, on the whole west coast of America, and, as I 

 believe, of Africa (?), and round the eastern islands in the 

 Atlantic ocean. Although certain species of lamelliform 

 zoophytes are found on the shores of the latter islands, and 

 though calcareous matter is abundant to excess, yet reefs 

 are never formed. It would appear that the effective species 

 do not occur there ; of which circumstance I apprehend no 

 explanation can be given, any more than why it has 

 been ordained that certain plants, as heaths, should be 

 absent from the New World, although so common in the 

 Old. 



Without entering into any minute geographical details, 

 I must observe, that the usual direction of the island groups 

 in the central parts of the Pacific, is N.W. and S.E. This 

 must be noticed, because subterranean disturbances are 

 known to follow the coast lines of the land. Commencing 

 on the shores of America, there are abundant proofs that the 

 greater part has been elevated within the recent period, 

 but as coral reefs do not occur there, it is not immediately 

 connected with our present subject. Immediately adjoin- 

 ing the continent there is an extent of ocean remarkably 

 free from islands, and where of course there exists no possible 

 indication of any change of level. We then come to a N. W. 

 by W. line dividing the open sea from one strewed with 

 lagoon islands, and including the two beautiful groups of 

 encircled islands the Society and Georgian Archii^elagoes. 

 This great band having a length of more than four thousand 

 miles by six hundred broad must, according to our view, be an 

 area of subsidence. We will at present for convenience sake 



