526 Taylor. Endemism in the BaJiama Flora. 



subsidence and emergence is unquestioned. Separating this group from 

 those of the Great Bahama Bank, however, there is a passage of over five 

 thousand feet depth. All the islands on the Great Bahama Bank are only 

 just above the surface, the bank itself having scarcely 20 feet of water over 

 it, so that they have been connected among themselves at some period of 

 their history. All of the islands scattered to the southward of the Great 

 Bahama Bank (group c) are surrounded by such depths of water that from 

 it and from one another they must have been separated no matter what the 

 local fluctuations of level throughout the archipelago may have been. 

 Evidence collected by Alexander Agassiz and more recently by the 

 Geographical Society of Baltimore puts the extreme changes of level 

 throughout the islands as not over 200 feet. The oceanic depths between 

 the Little Bahama and Great Bahama Banks and scattered islands to the 

 southward are so great that no dry land connexion between them could 

 have been possible. The authors of ' The Bahama Flora ' say in the 

 introduction to it, ' There is no evidence that there ever was land connexion 

 with either Florida, Cuba, or Hispaniola 5 [Haiti], a statement abundantly 

 justified by ocean depths often' in excess of twelve hundred feet and not 

 infrequently of over ten thousand feet. 



The amount of emergence and subsidence of the islands is pretty 

 accurately known, especially from the study of the ocean holes on the 

 banks. The depths of even the shallowest of these indicate that at some 

 period in the past, and not so very long ago, the archipelago must have 

 risen so far out of the water that the Bahamas must then have consisted 

 of one large island to the north, the Little Bahama Bank of to-day, another 

 and much larger island to the south, the Great Bahama Bank, and a group 

 of isolated islands to the southward, never connected with either of these 

 large land masses, nor with each other. The largest of the group is Inagua. 



The present Bahamas consist of wind and sea borne material piled up 

 at the time of this emergence, all the area within the dotted lines on the 

 map having since been covered by the sea, except for the islands exposed 

 at present, the 661 cays, and thousands of rocks, almost awash, that make 

 navigation so perilous. 



\b) Origin of Endemics. 



With only a single endemic genus, all the rest of the endemic species 

 are in genera that are found either on the Florida mainland, the larger 

 West Indies to the southward, or in many cases from more remote 

 regions. 



Of the 76 genera in which all the Bahama endemics are found, except 

 the endemic genus Ncobracea, 47, or 63 per cent., are genera mostly 

 containing numerous species of rather wide distribution. Nineteen, or 

 25 per cent., are genera found only in the West Indies or adjacent South 



