THE CORAL-REEF PROBLEM. 63 



more, in depth, on the assumption of internal solution, aided 

 by external acceleration as dependent upon an increased food 

 supply. It does not appear exactly clear why solution should 

 progress more rapidly within the lagoon than over the deeper 

 slopes of the coral buttress, where the protective power of the 

 living animal is also wanting; nor is it at all likely that such 

 solution as actually does take place within the lagoon more 

 than compensates for the accretion of sedimentary material 

 derived from the destruction of the surrounding shores, or for 

 the organic accumulation that is continuously forming along 

 the floor of the lagoon. 



My examination of the Bermudas convinces me that, as far 

 as those islands are concerned, the quantity of lime removed 

 from the interior waters is far less than that which is added 

 through sedimentation and organic development. The bot- 

 tom is everywhere covered with fine debris, and the even floor 

 indicates that this debris is of considerable thickness. One 

 has but to gaze upon the undercut and crumbling ledges of 

 Harrington Sound and the cliffs facing the lagoon to be con- 

 vinced that accumulation, and not solution, is the prevailing 

 condition in these waters. Yet we have here a depth of water 

 of from 50 to 80 feet. I am, indeed, far from convinced that 

 the organic accumulation which is here taking place by actual 

 growth does not far surpass the material removed through solu- 

 tion. The tests, both perfect and fragmentary, of Foraminifera 

 are abundant everywhere, but in addition to material derived 

 from this source, there exist large areas which are seemingly 

 well covered with the shells of molluscous animals (Chama, 

 Area, Avicula, etc.) and sea-urchins (Toxopneustes variegatus). 

 The latter, with Area Nose, are especially abundant. The 

 coral growth of Castle Harbor, and not less the insular 

 patches of millepore, etc., in the big lagoon, speak with suffi- 

 cient emphasis on this point. There can be no doubt, too, 

 that some of the basins and channels have been recently 

 shallowing through silting, but of course this may have been 

 brought about through a mere transference of material from 



