President's Address. 17 



the elevation, a portion of the sea-bottom was brought well 

 up into the waters of the Gulf Stream, which were probably- 

 shifted a little eastward. 



No marine fauna yet explored equals in variety of forms 

 or number of individuals that which peoples the waters of 

 the Caribbean Sea and the Gulf of Mexico, from a depth of 

 250 to about 1000 fathoms. This prolific life is traced by 

 Professor Agassiz to the copious food-supply carried by the 

 warm tropical currents, combined with the food borne outwards 

 from the seaboard of the continent. The corresponding 

 abundant fauna found by the " Challenger " in the Japanese 

 current may be regarded as its counterpart in the Pacific 

 Ocean. Professor Agassiz points also to the diminished rich- 

 ness of the fauna on the western sides of the continents as 

 being probably connected with the absence of those warm 

 equatorial currents which bring such an abundant supply of 

 food to the eastern shores. ''No one," he remarks, "who 

 has not dredged near the hundred-fathom line on the west 

 coast of the great Florida plateau can form any idea of the 

 amount of animal life which can be sustained upon a small 

 area, under suitable conditions of existence. It was no un- 

 common thing for us to bring up in the trawl or dredge large 

 fragments of the modern limestone, now in process of forma- 

 tion, consisting of the dead carcases of the very species now 

 living on the top of this recent limestone." MoUusks, echino- 

 derms, corals, alcyonoids, anuelides, Crustacea, and the like, 

 flourish in incredible abundance on the great submarine banks 

 and plateau, and cover them with a growing sheet of lime- 

 stone, which spreads over many thousands of square miles, 

 and may be hundreds of feet in thickness. In these com- 

 paratively shallow waters, and with such a prodigiously 

 prolific fauna, which supplies constant additions to the cal- 

 careous deposit, the solvent action of the carbonic acid upon 

 the dead calcareous organisms is no doubt reduced to a 

 minimum, so that the grow^th of the limestone is probably 

 more rapid than on almost any other portion of the sea- 

 bottom. 



From the charts we learn how extensively submarine 

 banks are developed in the West Indian region, in the track 



VOL. VIII. B 



