AGASSIZ : BAHAMAS. 43 



sense of atoll lagoons, but are merely small pot-holes or former banana- 

 holes which have come to be below high-water mark. Certainly there 

 seems to have been nothing written to prove that the present configura- 

 tion of the so called Bermuda atoll is directly due to the formation of 

 the coral reefs which are still growing "upon the bank, and their increase 

 in thickness owing to the subsidence of the bank. I shall return to 

 this subject in the description of my visit to the Bermudas. 



In the shallower places on the Bahama Bank the whole body of water 

 was discolored by the presence of sand stirred up by the action of the 

 waves, and it is only natural that in all those parts of the banks 

 where the water is constantly rendered turbid by moderate winds we 

 should meet with so little animal life ; for Gorgonians and corals can 

 only flourish in clear water, and even corallines cannot obtain a foot- 

 hold where the ripple-marks are too frequently changed or the bottom 

 sand is in constant motion. Between Nurse Cut and Kacoon Cut very 

 little animal life was to be seen on the bank. After passing Racoon Cut 

 we came upon a good many patches of coral heads and Corgonians. At 

 the same time the water was gradually deepening to the westward, and 

 we seemed, steaming parallel with the general trend of the cays, to be 

 cutting across a number of sand spits about at right angles to the shore 

 line of the cays, and trending in the general direction of the prevailing 

 winds. 



Great Ragged Island. 



Plate XI. Fig. 5. 



Great Ragged Island, the most southerly of the cays on the Great 

 Bahama Bank, does not differ in structure or appearance from the other 

 cays of the group. The rocks are seolian, hard, full of caverns and 

 cavities in the cliffs of the west side, with here and there fine sand 

 beaches between the spits of projecting rocks. At our anchorage the 

 coral sand was much coarser. After leaving the anchorage we passed 

 Hobsim's Breakers, to the south of Ragged Island, which are all that is 

 left of what must once have been an island of considerable size. 



Columbus Bank. 



Columbus Bank, which lies to the southeast of Ragged Island, is fully 

 exposed to the swell of the prevailing trades. Whatever cays onre ex- 

 isted upon it have disappeared, with the exception of Cay Verde and Cay 



