262 



PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



The discrepancy between the calculated and directly observed percent- 

 age of CaS04 in both samples is probably to be accounted for by greater 

 solubility of the CaS04 than of the carbonates under the conditions in which 

 they both exist in the sands. The sulphate in the calculated results is derived, 

 as will be seen from the tables, almost entirely from the algae. The deter- 

 minations of the composition of a\gx were made on fresh material, while 

 the sands have lain for some time, in their disintegrated condition and free 

 from their organic covering, in ocean water. 



BOTTOM SAMPLES FROM THE BAHAMAS. 



The Bahaman samples represent the following conditions: 



(i) The area just behind the barrier reef off Cocoanut Point, Andros Island. These 

 samples are Nos. 190 to 193. The general position of the area from which they 

 were obtained is indicated on the small-scale map, plate 95. and the more precise 

 position is shown on the map, figure 3. 



(2) The finely di\4ded mud accumulating in stagnant areas in South Bight 



No. 79, see plate 9^. 



(3) The finely divided, oolitic mud forming off the west end of South Bight 



No. 87, see plate 95. 



(4) Shore material, subject to tidal overflow on the west side of Andros Island, near the 



mouth of South Bight. Sample No. 83, see plate 95. 



Sample 

 Sample 



Channel obstructed by 

 Dangerous coral heads '0 



'i 10 



% J* 

 UnrSablJi \ 9 ..''^ *>'"> bottom 



viiWeio-ife.V 9 f^r^ Si-"--' -VS. 



patches '^\ 



,erou3 "V 

 10 ■ 



dy bottom ,(jv-» 

 -red with ,rt V 

 I heads 







O O 





/ ^ 



l/-i-i 



6 \\ 



?? 



Q 



\^. 



9 



KJ 



i. Good anchorage 



Fig. 3. — Map of Bethel Entrance, Andros Island, Bahamas. 

 Position of light, Lat. 25° 8" N., Long. 78° o' 30" W. From a plane-table survey by Alfred G. Mayer, May 1914. 



