122 BULLETIN OF THE 



Nicholas and Santaren channels were quite successful, as far as the 

 soundings and current observations were concerned; but the few dredg- 

 ings with which we had to be contented, for want of time and good 

 weather, did not produce much of interest. We were more successful 

 on the slope or so-called apron of the reef. Here the great advantage 

 of having a safe anchorage every night inside the reef, and within half 

 a mile of the field of work, allowed the soundings and dredgings to be 

 carried on with great rapidity and success. 



Tlie six lines run (as far as possible normally to the reef) were the 

 following : Off Coffin's Patches with only two dredgings ; off Sombrero 

 Light with seven dredgings, between 111 and 517 fathoms; off Bahia 

 Honda thirteen dredgings, from 19 to 418 fathoms; off the American 

 Shoal fourteen dredgings, from 16 to 2GG fathoms; off the Samboes 

 nineteen dredgings, from 13 to 298 fathoms; and off Sand Key twenty 

 dredgings, from 23 to 306 fathoms. Besides these, numerous casts were 

 made in 100 and 120 fathoms off Sand Key, whilst current observations 

 were in progress. 



The figures and the character of the bottom developed by the dif- 

 ferent lines were found quite concordant. At an average the slope, after 

 leaving the reef, is uniform for four or five miles, and the bottom is com- 

 posed of more or less comminuted shells and corals, with a rather 

 scanty living Fauna. This we may call the first region. The next ex- 

 tends in the form of a band parallel to the reef, ten to twenty miles 

 broad, beginning at a depth of about 90 fathoms, and extending to about 

 300 ; the slope being much less inclined than in the first region, and in 

 fact deserving in a great part of its extent the name of a submarine 

 plateau. The bottom is rocky, rather rough, and consists of a recent 

 limestone, continually though slowly increasing from the accumulation 

 of the calcareous debris of the numerous small ("orals. Echinoderms, and 

 Mollusks living on its surface. These debris are consolidated by the 

 tubes of Serpulaj, the interstices filled up by Foraminifera, and further 

 smoothed over by Nullipores. It is not unreasonable to suppose that we 

 have here the foundation of a future reef, which, when in the course of 

 ages it shall have approached the surface, will be covered with a growth 

 of Madrepores and Astreans, such as we find on the present barrier 

 reef, and as have lived on the Conner reel's constituting the chain of the 

 Florida Key-, the border of the main-land of the peninsula 3 and prob- 

 ably some older as yet unexplored one.- in the Everglades. 



