214 THE BERMUDA ISLANDS. 



the reef-builders do not really help him ; and that till he can 

 do this he is only supporting hypothesis by hypothesis" 

 (Nature, July 4, 1889).* The same objection probably holds 

 to any inference being drawn from the discovery of a number 

 of reef-genera (Stylophora, Astrsea, Pavonia, Cycloseris, Lepto- 

 seris, Stephanaria, Psammocora, Montipora, Alveopora, Rhoda- 

 roea in depths exceeding 30 fathoms off' the Tizard and Mac- 

 clesfield banks, as reported by Bassett-Smith (Nature, July 4, 

 1889). At all events, more detailed information than we now 

 possess regarding this seemingly important find is needed be- 

 fore satisfactory conclusions can be based upon it. 



There is another point with reference to the existence of 

 what might be called the second or deeper zone of coral growth, 

 which is supposed to be separated by a barren sand area 

 from the normal zone (100-120 feet), upon which Mr. Guppy 

 is not very clear. It is assumed that the sand resulting from 

 oceanic degradation destroys the life over which it is largely 

 precipitated, and that were it not for its bad influence corals 

 would be found growing on the deeper sea-ward slope as they 

 are found growing' above. The first part of the proposition is 

 in a measure doubtless true, but the second does not necessarily 

 follow ; on the contrary, the fact that these corals are practically 

 never found in the " barren " area is almost positive evidence 

 against the truth of the proposition. Otherwise we should find 

 scattered and luxuriant growths just as we find them in the 

 interiors of the sand-swept lagoons. According to Guppy the 

 lagoons and lagoon channels of the Solomon Islands are largely 

 occupied "by sand and chalky mud; but in the shallower 

 portions, and especially in those situations which are near the 

 breaks in the reef, corals thrive in great profusion " (Proc. 

 Royal Soc. Edinburgh, 1885-86, p. 861). 



In the lagoon of Oima the individual coral-colonies are de- 

 scribed as being very much larger than they are on the outer 

 slope of the reef; " large masses of Porites ranged from 10 to 16 



* I regret that up to the time of printing it has been impossible for me to secure a 

 copy of the new edition of Darwin's work on coral islands, edited by Prof. Bonney. 



