286 ALEXANDER AGASSIZ 



many doubtful points as to the structure of the Florida 

 Peuiusula. 



I am much pleased at what you say of my address ; 

 the part you refer to is just the one which seemed to 

 me to throw some light on the infinite lines of affinities, 

 which close study reveals, among otherwise distinctly 

 related groups, and it was the very difficulty of express- 

 ing this affinity by any of our present methods of nota- 

 tion which made me almost despair of doing more than 

 to follow a single character in its endless modifications 

 in time and space. 



During a visit to the Hawaiian Islands in 1885, his 

 examination of the coral reefs convinced Agassiz that 

 this was another region not explained by Darwin's theory. 

 The only indications of subsidence he found were slight 

 and local ; and he explains the great width of some of 

 the reefs by the growth of the corals seaward on their 

 own talus, a process which he points out might in time 

 produce a very great thickness of coral rock. In some 

 places, as in Kaneohe Bay, he was able to determine 

 that the modern reef forms only a thin crust over the 

 underlying volcanic rock. He believed the barrier reef 

 of Kaneohe Bay to rest upon a platform formed by the 

 washing down and disintegration of a lava crest to a 

 depth at which corals could flourish — the first instance 

 where such a formation had been noted. He was also 

 able to show that the more elevated limestone rocks 

 were seolian, that is, they had been formed of the sand 

 from coral beaches blown into dunes by the action of 

 the wind, and cemented by rain-water into rock. 



The supporters of Darwin's theory answered Agassiz's 

 report on the coral reefs of the Hawaiian Islands by 



