VIEWS OF PROF. A. AGASSIZ. 
287 
Professor A. Agassiz 1 accepts the views of L. Agassiz, 
Le Conte, and E. B. Hunt, that the Florida reefs can- 
not be explained by subsidence, but that the southern 
extremity of Florida is of comparatively recent growth, 
consisting of concentric barrier-reefs which have been 
gradually converted into land by the accumulation of in- 
tervening mud-flats, and thus explains the details of the 
process and the manner in which the foundations of the 
reefs are formed. 
He rejects Le Conte’s explanation that the substructure 
of the reefs was formed by the mass of material brought 
by the Gulf Stream, pointing out that more recent investi- 
gations have shown that it ran across, not parallel with, the 
peninsula, the curve of the eastern shore of the latter being 
due to a counter-current along the reef running westwards. 
The Gulf Stream, however, has an indirect influence by 
reason of the abundant food which it supplies to animals 
living on the Bank of Florida. Across the reefs, and 
through the channels between the Keys, the tides set 
strongly, bearing the mud derived from coral and other 
organisms ; this gradually accumulates to form the inter- 
vening mud-flats, and when swept westwards enlarges the 
submarine plateau in that direction. The Tortugas, the 
most recent cluster of Florida reefs, are at the very ex- 
tremity of the slope upon which the line of these reefs 
has been built up. Nothing among them corresponds 
1 Agassiz, Alexander. The Tortugas and Florida Reefs. Mem. 
Amer. Acad. Arts and Sci., vol. xi. p. 107, 1885. In Three Cruises of 
the Blake, vol i. (Bulletin of the Museum of Comparative Zoology, 
Harvard College, vol. xiv., 1888), a chapter is devoted to the Florida 
Reefs. As, however, the line of argument and the principal facts are 
identical with those given above, I have not thought it necessary to 
give a separate analysis. A convenient and clear summary of the 
views of Semper, Rein, Murray, and Agassiz is given by Prof. A. Geiki9 
in his presidential address to the Royal Physical Society of Edinburgh 
in 1883 (Proc. vol. viii. p, 1). 
