70 PHYSIOGNOMY OF PLANTS. 



del Rey y de la Reyna) . It was Columbus himself who, on 

 his second voyage, in May 1494, gave that name to this 

 little group of islands, because the agreeable mixture of the 

 silver-leaved arborescent Tournefortia gnapholoides, flower- 

 ing species of Dolichos, Avicennia nitida, and mangrove 

 hedges, gave to the coral islands the appearance of a group 

 of floating gardens. " Son Cayos verdes y graciosos llenos 

 de arboledas," says the Admiral. On the' passage from Ba- 

 tabano to Trinidad de Cuba, I remained several days in 

 these gardens, situated to the east of the larger island, called 

 the Isla de Pinos, which is rich in mahogany trees : my 

 stay was for the purpose of determining the longitude of the 

 different keys (Cayos). The Cayo Mamenco, Cayo Bonito, 

 Cayo de Diego Perez, and Cayo de piedras, are coral islands 

 rising only from eight to fourteen inches above the level of 

 the sea. The upper edge of the reef does not consist simply 

 of blocks of dead coral ; it is rather a true conglomerate, in 

 which angular pieces of coral, cemented together with grains 

 of quartz, are embedded. In the Cayo de piedras I saw 

 such embedded pieces of coral measuring as much as three 

 cubic feet. Several of the small West Indian coral islands 

 have fresh water, a phenomenon which, wherever it presents 

 itself, (for example, at Radak in the Pacific ; see Chamisso 

 in Kotzebue's Entdeckungs-Reise, Bd. iii. S. 108), is de- 

 serving of examination, as it has sometimes been ascribed 

 to hydrostatic pressure operating from a distant coast, (as 

 at Venice, and in the Bay of Xagua east of Batabano), and 

 sometimes to the filtration of rain water. (See my Essai 

 politique sur Tile de Cuba, T. ii. p. 137.) 



