176 CORALS AND CORAL LSLANDS. 



vegetable matter. This scanty soil is fertile, if well used. 

 When uncleared, it is covered with bush and forest trees. 

 There are also sandy tracts termed ' pine-barrens,' where the 

 bush suddenly disappears and the palmettos become fewer in 

 number, though enough remain to exhibit an intermixture of 

 pines and palms, respectively typical of the northern and 

 southern floras. The lowest portions of the flat grounds fre- 

 quently contain small brackish water or salt lakes. In the 

 chalk- marsh of Andros Island, however, there is a freshwater 

 lake, with three streams as its outlets; and it appears that 

 there is no other freshwater lake or stream in the Bahamas. . 

 . . . There are large caverns in Long Cay and Rum Cay ; 

 and probably caverns are as numerous in the Bahama Islands 

 as in the Bermudas ; but so few extensive excavations have 



been made, that this cannot be positively aflEirmed 



One of the most striking objects in the topography of the 

 Bahamas is the very deep submarine valley forming the gulf 

 known as ' the Tongue of the Ocean,' which runs into the 

 Great Bahama Bank from its northern end. The colour of the 

 water around the islands is usually that of the aqita-viariiie 

 variety of beryl ; but the water of the Tongue of the Ocean 

 has the deep blue colour of oceanic depths. 



" The author describes a coral-reef as consisting of masses of 

 numerous species of Madrcpora, Astrcea, Dcedalea, Oculina, 

 bases and axes of Gorgonia, Millepora, Nullipora^ CoralUnce, 

 &c. &c., growing confusedly together without any other apparent 

 order than that of accidental succession and accretion, both 

 laterally and vertically. These are at times aided or even super- 

 seded by Serpulce^ &c., as seen in the serpuline reefs. . . . 



" Captain Nelson points out a few of the localities that exhibit 

 most clearly the character, source, and mode of aggregation of 

 the materials of the ordinary Bahama rock, such as is formed 

 above the sea-level ; at the same time referring to the illustra- 

 tive specimens in the Bahama collection. For instance : the 

 south side of Silver Cay and the beach extending westward 

 from Nassau aftbrd rolled blocks, pebbles, and sand derived 

 from the massive corals, mixed with remains of turtles, fish, 



