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

 By Alexandek Agassiz. 



Before giving the results of ray observations on the Coral Reefs of 

 the Sandwich Islands, it may be useful to recapitulate the salient points 

 of the older theories of the formation of the coral reefs, from Chamisso's 

 (1815-1818) to Darwin's (1842), as well as the modification of the lat- 

 ter by Dana (1838-1842, 1849), and to enumerate briefly the objections 

 which have been made to the general application of the theory of sub- 

 sidence to the special cases examined by later investigators, from Agassiz 

 (1851) to the present time. 



I need only refer to the earlier views of Forster, who imagined coral 

 reefs to have been built up from the bottom of the ocean, a view which 

 was naturally untenable after the observations of Quoy and Gaymard on 

 the limits of depth at which corals appai'ently thrive, as well as the later 

 observations of Ehrenberg on the coral reefs of the Red Sea. 



Darwin, it should be remembered, examined only the Great Chagos 

 Bank, and based his speculations on the observations he made on this 

 single group, supplementing the knowledge, however, by a most exhaust- 

 ive analysis of the observations and descriptions of others, and a 

 most thorough examination of the hydrographic charts which had 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 hydrographic 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, wdnle 

 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. 



