THE CORAL-REEF PROBLEISI. 73 



days of Darwin and Dana, it seems unnecessan,^ to account for 

 their presence by a gigantic subsidence, of which although we 

 may not deny it, we can yet have but httle positive proof" 

 (p. 131). These reflections are well so far as they go, but have 

 the " natural and far simpler causes '" underlying the forma- 

 tion of coral reefs, which are to take precedence over the Dar- 

 winian hypothesis, been satisfactorily demonstrated ? I believe 

 not, and I further believe with Dana and ^^on Lendenfeld that 

 no facts that have yet been brought forward stand in direct op- 

 p< sition to the theory of subsidence.* ]\Ir. Agassiz assures us 

 that the " Mosquito Bank, the Yucatan Bank, and the smaller 

 banks between Honduras and Jamaica, are all proof that 

 limestone banks are forming at any depth in the sea, or upon 

 pre-existing telluric folds or peaks, constituting banks upon 

 which, when they have reached a certain depth, corals will 

 grow " (p. 133). and a similar condition is considered to under- 

 lie the formation of the Florida reefs. It has, however, )wt 

 been shown that these banks have been actually built up in 

 the manner that has been described, or that any other banks 

 have been similarly reared from really great depths. The 

 assertion that the Florida reefs have not been assisted in their 

 upward growth by elevation (p. 142) is, as far as I can see, not 

 supported by fact, for we have in the regular horizontal lime- 

 stone beds of the southern part of the peninsula the most con- 

 clusive evidence of elevation even as late as the Pliocene and 

 Post-Pliocene periods, and there is every reason to believe, 

 even if the condition cannot be proved, that this upward 

 movement did not stop short of the coral-forming tract. Nor 

 does this moviement of elevation preclude the possibility of 

 subsidences having taken place coincidentally in the same re- 

 gion. It appears to me by no means certain that the deep 

 channel now separating the apex of the peninsula of Florida 

 from Cuba, and known as the Straits of Florida, was really 

 cut by the Gulf Stream, as is maintained by Mr. Agassiz. It 

 seems to me far more probable that it, as well as some of the 



*Kaiufwisien5(ka/lluhe Kuntlsihau, Oct. 13, 18SS. 



