FOSSILS OF THE BAHAMA ISLANDS, WITH A 

 LIST OF THE NON-MARINE MOLLUSKS 



BY 



WILLIAM H. DALL, A. M., Sc. D., 



Curator Division of Mollusks, U. 8. National Museum. 



INTRODUCTION. 



The material submitted to me by Dr. George B. Shattuck was chiefly 

 collected by Dr. B. L. Miller, of Bryn Mawr College, and comprised specimens 

 of the various calcareous rocks containing organic remains, as well as some 

 fossils which had been removed from their associated matrix, all fully labelled 

 with locality and other data. 



The rocks may be divided into two general groups, those which were 

 formed in water, or sedimentary; and those formed of drifted sands more or 

 less consolidated, or aeolian. 



In the main the fossils of the sedimentary rocks are of marine origin 

 while those of the aeolian rocks are landshells, but in both there is some 

 mixture, as dead marine shells from the beaches were included in the aeolian 

 sands, or landshells washed or blown into the sea in the sedimentary beds, as 

 happens daily under present conditions. 



All the material of both kinds of rock is ultimately organic or has been 

 derived from the sea water through the medium of organisms which have 

 secreted it in solid form, which has subsequently been reduced to sand by 

 attrition and reconsolidated by partial resolution and deposition. In a broad 

 sense this applies to both lime and silica as contained in these rocks, and 

 more or less mingled with phosphoric acid and oxides of manganese or iron, 

 of which the proportions in general are very small. 



It is probable that the amount of sand derived from crystalline rocks of 

 the adjacent region, except in the form of floating pumice, is almost infini- 

 tesimal. 



The fundamental rock of the Bahamas is sedimentary and was deposited 

 at a moderate depth below the sea at a very recent geological epoch, all the 



