14 SHALLOW-WATER FORAMINIFERA OF TORTUGAS REGION. 



RELATION OF THE TORTUGAS FAUNA TO THOSE 

 OF OTHER REGIONS. 



While at Key West, opportunity was taken to make two col- 

 lections of bottom material among the keys. A comparison of these 

 with the bottom samples from the Tortugas shows that some of the 

 species common at Key West are not represented in the Tortugas 

 collection. This shows the change even in this short distance. A 

 comparison with the fauna of the north shore of Jamaica and that 

 from the Bahamas shows differences in all these locahties, although 

 conditions of temperature, etc., are not great. It tends to show that 

 the Foraminifera are not universally distributed, but even within 

 a limited area have a definite distribution. 



Many of the Tortugas species are closely related to those of the 

 general Indo-Pacific region. Some of the genera in this collection 

 are here recorded for the first time from the Atlantic. These are 

 known from various parts of the Indo-Pacific in warm, shallow waters. 

 Whether their distribution in the West Indian region is wide remains 

 to be shown by further work. It is certain that in general the 

 foraminiferal fauna of the Tortugas and that of the shallow water of 

 the West Indian region also are much more closely related to the 

 Indo-Pacific than to any other part of the Atlantic. 



This fauna of the Tortugas is, again, more or less closely related 

 to the fossil faunas of the Tertiary of the Coastal Plain of the United 

 States. Some of the relations, especially with the Lower Oligocene 

 of Mississippi and Alabama, are very interesting and will be made 

 use of when the fauna of the Lower Oligocene is published. 



STATIONS AND DATA. 



While at the Tortugas, nearly 50 stations were occupied, and in 

 most cases bottom samples were obtained. Of these, 20 were 

 selected for detailed study, giving very well the varied conditions 

 of the region from the warm, almost stagnant water of the moat at 

 Fort Jefferson on Garden Key and the lagoon on Long Key to the 

 quiet waters of greater depth, such as Bird Key harbor, the waters 

 of the channels among the keys, and the open water outside the 

 reefs. An extension into water of 50 or 100 fathoms would greatly 

 increase the number of species, but the present list of species and 

 varieties is very fair for such a limited region in shallow water. 

 This compares with species from the north coast of Jamaica, 

 although the latter represented a very few stations in comparison. 



The accompanying map of the region shows the location of the 

 stations given here, and also the data for these stations. 



14 



