No. 3. — The Coral Beefs of the Havjaiian Islands. 

 By Alexander Agassiz. 



Note. — The present number of the Bulletin has been completed since last 

 autumn, but its distribution has been delayed for two months, owing to my absence 

 from Cambridge. On my return to this country I find an article by Professor J. D. 

 Dana, in the February number of the American Journal of Science, on the "Geo- 

 logical History of Oahu," which I am unfortunately unable to discuss in this paper. 

 I can only call attention in this note to the fact that he looks upon the data fur- 

 nished by the borings of the artesian wells of Oahu as evidence that the island has 

 probably subsided to the extent of eight hundred feet, that being the distance below 

 the surface at which reef rock has been passed through below the coral-growing 

 limit. But, as he says, " the fossils of the reef rock passed through below the coral- 

 growing limit have not been examined, and the subsidence is therefore not positively 

 proved." My own explanation of the same borings is found on page 150 of this 

 paper. 



Cambridge, April, 1889. 



most tnorougn examination oi me iiyurugrupuio unaiLs wmun uau any 

 bearing on the subject. But no naturalist has had opportunities to 

 make a personal examination of the conditions of growth of corals and 

 of coral islands such as have been enjoyed by Dana, as geologist of the 

 United States Exploring Expedition. His Report on Coral Reefs and 

 Islands, published in 1849, contains a full account of his own observa- 

 tions (1838-1842) on the Hawaiian Islands, the Society Islands, the 

 Samoa and Viti groups, and his theories are based upon his own experi- 

 ence, far wider than that of any other writer on the subject. He has 

 therefore drawn but little either from the descriptions of the voyagers of 

 the early part of this century, or from the hydi'ographic charts, both of 

 which form so essential a part in the Darwinian theory of coral reefs. 



■ An examination of the hydrographic charts of the coral reefs, while 

 interesting, can lead to no sound conclusion. Well as I know the 

 Florida reefs and part of the Bahamas, as well as the majority of the 

 West India coral reefs, I should hesitate to base any general conclusions 



VOL. XVII. — NO. 3. 



