BOTTOM SAMPLES, MURRAY ISLAND, THE BAHAMAS, AND FLORIDA. 247 



Chemical analyses of foraminifera important as contributors to deposits in coral-reef areas. 



(1) Tinoporus baculatus (Montfort) Carpenter, from Murray Island. 



(2) Polytrema mineaceum (Linn.), from Cocoanut Point, Andros Island, Bahamas. 



(3) Orbiculina adunca (Fichtel and Moll), from Key West, Florida. 



(4) Orbitolites marginalia (Lam.), from south of Tortugas, depth 17 fathoms. 



(5) Quinqudoculina auberiana d'Orbigny, from south of Tortugas, depth 17 fathoms. 



Analyses of I, 2, 3, 4, by W. C. Wheeler; of 5 by Alfred A. Chambers. 



'Organic matter + CO2 -+- H 2 0. 



Analyses of Corallinaceous algae (made by Alfred A. Chambers), pre- 

 sented on the next page, are additions to the series originally contained in the 

 memoir by Messrs. Clarke and Wheeler, referred toon page 240 of this paper. 



The specimen on shore, above high tide, line I, southeast reef, is com- 

 posed of 80.1 per cent of fine gravel and 18.5 per cent of coarse sand, the 

 two sizes aggregating 98.6 per cent of the sample. This specimen contains 

 much basaltic gravel, as would be expected on the shore of a volcanic island. 

 It is highly noteworthy that even 200 feet from shore on the southeast reef 

 Si0 2 + (A1, Fe) 2 3 together constitute only 0.63 per cent of the sample, showing 

 that the volcanic material is not carried seaward in an appreciable amount. 

 Reference to the quotation from Dr. Mayer's article (page 245) will give the 

 explanation of the small percentage of these constituents. 



The prevailing winds are from the southeast; the currents sheer around 

 the island, and carry northwestward any material which has been sufficiently 

 comminuted. Dr. Mayer mentions that lava boulders extend "fully 200 

 feet from mean low tide," but judging from the chemical analysis the fine 



