134 BULLETIN OF THE 



who examined the Florida Reefs iu 1851, nor Joseph Leconte, 1 his as- 

 sistant, who published subsequently views somewhat different from 

 those of L. Agassiz, nor E. B. Hunt, 2 who promulgated a theory of the 

 formation of the Florida Eeefs, nor A. Agassiz, who spent several sea- 

 sons in parts of Florida, on the Florida Keys, and on the Tortugas, 

 was able to accept Darwin's theory as offering an explanation of 

 the formation of the great reef extending from the Tortugas to Cape 

 Florida. 



Agassiz, while in general he accepted Darwin's theory as applicable to 

 atolls, yet gave, in 1851, (Report of United States Coast Survey, repub- 

 lished with additions in the Memoirs of the Museum of Comparative 

 Zoology,) an account of the Florida Reefs, showing the living reef out- 

 side of the lagoon, and its position with reference to the line of Keys. 

 I subsequently gave a number of sections of the same reef from the 

 Coast Survey maps, 3 showing the formation of a barrier reef actually 

 going on, where the reef foundation grows lower and lower, and where 

 we need not have recourse to the theory of solution for the formation 

 of a lagoon. The lagoon we can actually trace from its broadest point 

 at the Rebecca shoal, where the reef is submerged, to its narrowest point 

 at the northern extremity of the reef. 



Leconte accepts the theory of subsidence as a satisfactory explanation 

 of the formation of atolls in the Pacific Ocean ; but in Florida, which he 

 visited with Professor Agassiz in 1851, he agrees with the latter in his 

 account of the formation of a barrier reef where there has been no sub- 

 sidence, and then he points to the Gulf Stream running parallel with 

 the trend of Florida, as the agent which has deposited the great mass of 

 the Florida bank below the level at which corals can grow. But there 

 is no evidence that the Gulf Stream ever ran in the direction assumed 

 by Leconte. Agassiz also accepted the theory of subsidence as generally 

 explaining the formation of the different kinds of coral reefs, though in 

 his account of the formation of the Florida Reef he does not go beyond 

 the depths at which reefs grow, and says nothing of the substructure or 

 foundation rock. In February, 1878, 4 I called attention to the exist- 



1 Am. Jour. Science, XXIII., May, 1857, p. 46, " On the Agency of the Gulf 

 Stream in the Formation of the Peninsula and Keys of Florida," by Joseph 

 Leconte ; also Elements of Geology, New York, 1878. 



2 Hunt, E. B., Am. Jour. Sci., 1863, Vol XXXV. p. 197. 



3 In the Tortugas and Florida Reefs, Memoirs of the American Academy, Vol. 

 XL, 1883. 



4 Agassiz, A., Letter No. 1 to C. P. Patterson, Supt, on the Dredging Opera- 

 tions of the U. S. Coast Survey Steamer Blake, Bull. Mus. Comp. Zool., V., No. 1, 

 1878. 



