MUSEUM OF COMPARATIVE ZOOLOGY. 133 



sidence. It may also be that erosion has been amply capable of washing 

 away the land connections, and forming the banks on which the islands 

 rest as it were. 



As to there not being any mound now approaching the ocean sur- 

 face in the western border of the Gulf Stream, the past history of the 

 Gulf Stream itself, of the Florida Plateau, and of the formation of the- 

 Keys of Florida and of the present reef, seem to me to furnish just such 

 a foundation for reef-building as is required by Dana. The Mosquito 

 Bank, the Yucatan Bank, and the smaller banks between Honduras and 

 Jamaica, are all proof that immense 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. Is it claiming too much for erosion to say that some of the vol- 

 canic peaks may have been washed away and swept into the sea 1 Cer- 

 tainly this is not the case in any region where there is a rainy season. 

 The Sandwich Islands themselves, greatly modified as they have been by 

 erosion, furnish the best evidence that isolated peaks may have com- 

 pletely disappeared. A careful perusal of Dana's own account of the 

 effect of erosion on their topography, and of Captain Dutton's later 

 examination, shows how powerful a factor they regard erosion to have 

 been in these islands. And if we go farther towards the equator, or to 

 the region of cyclones and tornadoes, the action of erosion will be found 

 to be far more powerful than in the Sandwich Islands, which are on the 

 very edge of the rainy season district. 



It is somewhat surprising that, in the discussion which has lately 

 been carried on in the English reviews, 1 by the Duke of Argyll, Huxley, 

 Judd, and others, regarding the new theory of coral reefs, no one should 

 have dwelt upon the fact, that, with the exception of Dana, 2 Jukes, 3 

 and others who published their results on coral reefs soon after Dar- 

 win's theory took the scientific world by storm, 4 not a single recent 

 original investigator of coral reefs has been able to accept this explana- 

 tion as applicable to the special district which he himself examined. 

 It is interesting to note that, however widely Darwin's theory was 

 accepted and spread in all text-books of Geology, neither L. Agassiz, 5 



1 " Nature " and " Fortnightly Review." 

 . 2 Dana in 1838-1842 ; " Corals and Coral Reefs," in 1872. 



3 Jukes in 1845, Narrative of the Surveying Voyage of H. M. S. Fly, Vol. L 

 p. 31, 1847. 



4 Darwin in 1842, " The Structure and Distribution of Coral Reefs " ; Darwin's 

 Coral Reefs, 1874, 2d edition. 



5 Agassiz, L., TJ. S. Coast Survey Reports, 1851 and 1866 ; also Methods of Study 

 (popular sketch). See Vol. VII., Mem. Mus. Comp. Zool. 



