BOTTOM SAMPLES, MURRAY ISLAND, THE BAHAMAS, AND FLORIDA. 255 



more, SiOa and (Al, Fe)203 were rejected as being probably extraneous impur- 

 ities, very variable and generally very small in amount. The value used for 

 the composition of the algae as given in the preceding table is an approx- 

 imate mean of the composition of Corallinaceae and Halimeda. 



The following tables give the essential portions of the results obtained: 



Analysis of sample No. syj^ja, line I, 1,600 feet from shore. 



'Compound grains (4) regarded as proportionate mixture of other materials present and therefore ignored. 



'Assume same chemical composition as other calcareous algie. 



'Estimated. 'Ignore. SiOa and (Al, Fe)20j are not being calculated in the chemical composition. 



