14 



Nils Roeén 



At what time have the above mentioned subsidence and elevation of the Ba- 

 hamas taken place? Dall has tried (op. cit.) to state the time. The shells and 

 corals deposited during the epoch of subsidence, are all the same as those at present 

 found in shallow water in the Bahamas. The subsidence must be very recent. He 

 has also studied the fossils found in the œolian hills covering the stratum of marine 

 deposits, and consequently formed during the following elevation. These fossils 

 represent the remains of the fauna that occupied the islands immediatly after their 

 elevation. The vast number of them belong to the two shell-genera Cepolis and 

 Cfirion. According to Dall the fossil forms of these genera found in the Bahamas 

 resemble those now living in Cuba or Haiti more than they do the prevalent Bahama 

 living ones. They have invaded from Cuba and Haiti. These two genera take 

 their origin from the Oligocène period. During the Miocene epoch some of the 

 more tropical forms were eliminated. Some of the survivors have spread to the 



Bahamas as soon as they 

 were elevatad high enough 

 to be suitable for animal 

 beings and this elevation 

 consequently took place in 

 very late Tertiary time. 



From what has been 

 stated above, the Baha- 

 mas are from a zoo- 

 geographical point of 

 view to be considered 

 Fig. E. Sand-bcach (Stanniard Creek, Andros). as true oceanic is- 



lands. Whether there 



has been a former secondary connection with other land is of no 

 significance for the study of the recent fauna for the islands after 

 their formation were almost entirely submerged and the recent 

 fauna must have invaded since the beginning of the following 

 recent elevation, which took place in very late Tertiary time and 

 has g-iven the archipelago its present configuration. 



The features of the fauna that can take possession of an oceanic island depends 

 very much on the physical conditions offerred by this. I will make a few 

 remarks hereon ^ The Bahamas consist as has been mentioned, only of coral and 

 shell sand, which is often consolidated to a greater or less extent to limestone rock. Ow- 

 ing to solution the surface of the rock has a truly honeycombed appearance {Vig. A). 

 Some of the holes are small, some rather large, commonly spoken of as »banana-holes». 

 In many places the rock is very ragged and extremely pitted. The wind has often piled 

 up the sand to hills, running lengthwise of the islands, often in several series (Fig. C). 



/Û 



' For a detailed account liereof I roter to the work »The Bahama Islands», ed. by Shatxuck. 



