AGASSIZ : BAHAMAS. 161 



had failed to come to the notice of scientific men, have been described 

 by Professor Heilpriu.^ Is their absence due to the limited amount of 

 food brouglit by the current across the Yucatan Bank, sweeping as it 

 does northward towards tlie Tortugas and washing the shores of the 

 Florida Keys? The exposure of the coast of British Honduras and of 

 the Yucatan and Moscpiito Banks to the influence of the prevailing- 

 winds and currents, bringing with them a vast supply of pelagic food, is 

 probably the principal cause for the abundant growth of coral reefs in 

 all favorable localities on the Yucatan and Mosquito Banks and along 

 the British Hondui-as coast, as well aa upon the weather faces of the 

 Serrana and Quita Sueno Banks, the Roncador Reef, Old Providence, 

 St. Andrews, and the Courtown and the Albuquerque Cays. 



The Reefs of the Yucatan Bank. 



On the Yucatan Bank (Hydrographic Charts Nos. 1234, 1 235), with the 

 exception of the Alacran atoll, the reefs are merely more or less irregu- 

 larly shaped patches, either surrounding the cays wholly, or reaching 

 out from them, and rising generally from the 3 to 5 fathom line of the 

 bank itself. This is the case with the Areas Cays and the Triangles 

 (Hydrographic Chart No. 1239). The Obispo Shoals (Hydrographic 

 Charts Nos. 403, 1239, Admiralty Chart No. 1830) and the Sisal Reefs 

 are small irregular patches rising from the 5 or 6 fathom line, while 

 Madagascar Reef is a narrow coral ridge about two miles long, rising 

 from the 7 to 11 fathom line with from one and a half to three fathoms 

 of water upon it. On the extension of the Yucatan Bank plateau to the 

 westward there are also a few patches of reefs off' the Barra de Tuxpan 

 and scattered patches off Champoton, but neither these nor the reefs off 

 Vera Cruz, along the inshore edge of the narrow shore platform of the 

 west coast of the Gulf of Mexico, can be considered as reefs of any im- 

 portance. And indeed they are so unimportant that it was not unnat- 

 ural for Darwin and Dana to speak of the Mexican coast of the Gulf of 

 Mexico as free from coral reefs. 



Along the Yucatan coast to the south of Cape Catoche, Mugcres Har- 

 bor (Hydrographic Charts Nos. 402, 1379) is formed by the extension 

 northward of the two fringing reefs which run along the east and west 

 face of the island and pass into the shifting ledges forming the Blancas 

 Lagoon. Corals are reported upon Arrowsmith Bank in twelve fathoms, 



Cozumel (Hydrographic Charts Nos. 402, 1380) is flat, not more 



1 Proc. Phil. Acad. Nat. Sci., 1890, p. 303. 



VOL. XXVI. — NO 1, 11 



