584 PROCEEDINGS OF THE AMERICAN ACADEMY. 



that it results in the choking of all organisms on the bottom, except 

 where tides or waves sweep it away. A good example of such distribu- 

 tion of deposits is seen in Murray Anchorage, where, in the sheltered 

 northern half, the bottom is almost wholly marl, while in the Ship Chan- 

 nel near by there is a strong tidal current and a bottom of shell sand. 

 A striking example of the silting in of sedentary organisms was found 

 by Herdman (:03) in his study of the pearl oyster beds of Ceylon, 

 where, during a single year, a bed of several millions of young oysters 

 was destroyed and entirely hidden by shifting sands. 



Heilprin ('89) emphatically denies the supposition that solution can 

 have any significant effect in keeping the lagoons and channels open ; it 

 is certain that the marl and shell sand are building up and levelling the 

 surface of the plateau much faster than the water can possibly dissolve 

 it, by which, however, I do not mean that the surface of the bank is as a 

 whole rising. Agassiz ('95) has already shown the great importance of 

 the solvent action of sea water on limestones in honeycombing and un- 

 dermining cliffs and ledges, and in certain localities the same action is 

 clearly shown in the worn and honeycombed condition of the shells and 

 other fragments in the sand. 



List of Stations at which Bottom Samples were 

 collected.* 



No. Map No. 



1903. 



313. 64= 43' 47" W. ; 32° 20' 18" N. Off Crawl Point, 5 fathoms. 3 



314. 64° 42' 50" W.; 32° 20' 45" N. N. of [Bailey's] Bay Id., 8 fms. 2 

 317. 64° 43' 03" W. ; 32° 20' 30" N. Mouth of Bailey's Bay, 3 fms. 3 

 319. 64° 51' 07" W.; 32° 18' 10" N. Mangrove Bay. 4 



323. 64° 50' 32" W. ; 32° 19' 24" N. West of Ireland Id., 7 fms. 4 



324. 64° 43' 50" W. ; 32° 25' 15" N. Three Hill Shoals, 8^ fms. 1 



* Tlie position of each of the various stations is indicated on tlie accompanying 

 maps by two marginal lines, one for latitude and one for longitude. After the 

 maps were prepared it was discovered tliat there was a discrepancy of about 20" 

 in latitude between the British Admiralty Cliart, on which Map 1 is based, and the 

 recent Ordinance Survey Map, on wliich Maps 2-4 are based. A correction of 

 plus 20" is to be applied to the latitude of any place indicated on Maps 2-4 to bring 

 it to the corresponding place on Map 1 ; or a correction of minus 20" to places on 

 Map 1 to make them fall at the right place on Maps 2-4. 



The location of any given station was determined on one or otlier of these maps, 

 and the latitude and longitude here recorded is that of the given place on that map. 

 Where the haul extended over some distance, the middle point of the haul is tiie 

 one noted on the map. — E. L. M. 



