DEPARTMENT OF MARINE BIOLOGY. 175 



what slower rate than do the corals at Tortugas, Florida; but his ener- 

 gies were mainly devoted to a study of the geologic history of the 

 Bahamas, and he traced clearly the several emergences and submer- 

 gences of the group since Pleistocene times. His special report should 

 be referred to for details, but it may be stated here that the Bahamas 

 were once at least 40 to 60 feet higher than they are at present and the 

 present archipelago of the Great Bahamas consisted largely of a great 

 island extending from the borders of the Gulf Stream to Eleuthera, 

 Exuma, Long Island, and Cay Verde on the east, and New Providence, 

 the Berry Islands, and Great Isaac on the north; thus the Great 

 Bahama Bank, together with Andros, was raised above the sea, form- 

 ing a huge U-shaped island with the deep tongue of the ocean in its 

 midst. 



Dr. Vaughan found the shore platforms, now submerged, which 

 marked the former sea-levels; he also gathered novel physiographic 

 data of importance, enabling him to ascertain the history of wave and 

 wind actions upon denuded shore-lines. 



It is now clearly demonstrated that the seolian formations of the 

 Bahamas are superimposed upon a limestone which was formed 

 beneath the sea, but is at present slightly elevated above the level 

 of the ocean. Dr. Vaughan thus supports and amplifies the view put 

 forth by Shattuck, which is opposed to that of Alexander Agassiz. 



A collection of corals was made on the barrier reef of Andros Island 

 at Bethel Entrance, and a map of this dangerous reef region was made 

 from a plane-table survey by the Director. 



Upon returning to Florida in June, Dr. Vaughan made observations 

 with Ekman meters upon the currents of the Hawk Channel, Rebecca 

 Channel, and Tortugas ; and as a result of dredging, both in the Baha- 

 mas and in Florida, he obtained data upon the extension of reef-corals 

 to depths down to 20 fathoms. 



Dr. Vaughan also continued his study of oolite formations and col- 

 lected samples of mud and of sea-water, the bacterial content of which 

 are being studied by Dr. Karl F. Kellerman, who finds that the '^Bac- 

 terium colds'' of Drew produces no precipitation of calcium carbonate 

 in sea-water unless in the presence of carbon dioxide. Indeed, for the 

 precipitation of calcium carbonate in sea-water, it appears necessary 

 to have an ammonium-producing organism act in association with one 

 which produces carbon dioxide. 



Throughout the period of Dr. Vaughan's association with the 

 Department of Marine Biology, he has been most generously aided in 

 his studies upon numerous occasions by the U. S. Geological Survey, 

 the Smithsonian Institution, the U. S. Bureau of Fisheries, the Depart- 

 ment of Agriculture, the U. S. Coast and Geodetic Survey, and the 

 Lighthouse Board, and it is with keen pleasure that as Director of the 

 Department I express warm appreciation of the kind acts of the officers 



