RECORDS. . 207 



Summary of Papers. 



Dr. Mayer said that the shallow Bahama banks are veritable 

 submarine deserts covered with finely divided silt and fragments 

 of the calcareous remains of marine animals and plants. The 

 corals grow in clusters chiefly on the outer edges of the banks 

 and may be compared to oases in the desert. 



The water of the banks is generally charged with a flocculent 

 mass of silt which is fatal to most of the pelagic animals. Ac- 

 cordingly the Bahamas have only about half as many species 

 of pelagic animals as the Tortugas, Florida. 



The exceptional richness of the Tortugas' fauna is also due 

 to the drift from the Gulf Stream caused by prevailing north- 

 east and southeast winds, while the fauna of the Bahamas is 

 depleted from the same cause. In other words the Bahamas 

 lie on the wrong side of the Gulf Stream for the study of pelagic 

 life. About one-half of the pelagic forms of the Bahamas are 

 equally abundant at the Tortugas ; but about one-quarter of the 

 remainder are more abundant at the Bahamas, and a few of 

 these seem to be confined exclusively to this region. 



The Bahamas are richer in species of corals and actinians than 

 the Tortugas, this being due to the fact that the coral-reefs of 

 the Tortugas were largely killed by a drift of dark-colored 

 water which passed over them in October, 1878, and have only 

 partially recovered. No more favorable situation for the study 

 of pelagic life has been discovered in the tropical Atlantic than 

 that of the Tortugas, Florida. 



Prof. Wilson's paper is to be published in a forthcoming 

 number of the Journal of Experimental Zoology. 



M. A. BiGELOW, 



Secretary. 



SECTION OF GEOLOGY AND MINERALOGY. 



December 14, 1903. 



Section met at 8:15 P. M., Professor J. F. Kemp presiding. 

 The minutes of the last meeting were read and approved. 

 The following program was then offered : » 



