226 THE BERMUDA ISLANDS. 



of the Wilkes Exploring Expedition the anchor of the " Pea- 

 cock" was dropped [within the reefs of Viti Lebu and Vanua 

 Lebu] sixty times in water from twelve to twenty-four fath- 

 oms deep, and in no case struck among growing corals. 

 Patches of reef were encountered at times, but they were at a 

 less depth than twelve fathoms " (Dana, " Corals and Coral Isl- 

 ands, 1872, p. 116). Alexander Agassiz's researches off the 

 Tortugas reefs lead to the conclusion "that corals do not thrive 

 below a depth of from six to seven fathoms," and the same 

 limit of growth was found by Louis Agassiz along the whole of 

 the main reef to the northward " (" Three Cruises of tlie Blake," 

 vol. I, p. 74, 1888). Walther found dead reef (supposed to have 

 been brought about by subsidence) at R^s Muhammed at a 

 depth of only 10 metres, or 30 feet (" Die Korallenriffe der Sinai- 

 halbinsel," p. 465, 1888). Why then should the observations of 

 such a careful investigator as Captain Moresby be called into 

 question ? It seems to me that they very closely agree with 

 the theory of subsidence. 



H. 0. Forbes. "A Naturalist's Wanderings in the Eastern Archipelago," 1885. 



The author describes the Keeling atoll, which he believes 

 to have risen through elevation, and finds reason to conclude 

 that the lagoons have filled in materially since the time of Dar- 

 win's visit. 



J. D. Dana. *' Origin of Coral Reefs and Islands." Am. Jburn. Science, .3d ser., vol. xxx, 

 1885. 



An elaborate review of the objections raised to the Darwin- 

 ian theory, and a statement of facts in support of said theory. 

 'J'his is by far tiie most searching analysis of the divergent 

 views bearing upon the theories of coral-reef formation, and, 

 as it appears to me, it satisfactorily meets all the objections 

 that have been raised against subsidence, besides showing the 

 inadequacy of the substitute theory. The author's main con- 

 clusions are thus stated (p. 190) : " The subsidence which the 

 Darwinian theory requires has not been opposed by the men- 

 tion of any fact at variance with it, nor by setting aside Dar- 



