CUSHMAN: BYRAM calcareous marl 20I 



foraminifera are concerned, having been found at no other 

 horizon. Conrad described it from the upper bed of Vicksburg 

 which is the equivalent of the Byram marl. 



Of the species to be described as new a considerable proportion I 



are represented in the Indo-Pacific region by closely allied species. 



Relationships to other lower Oligocene formations 



A number of the species of the Byram marl are found also in i 



the Mint Spring calcareous marl member of Marianna limestone, ; 



and a smaller number in the Red Bluff clay formations, which are ! 



found respectively below the Byram marl in Mississippi. Some 

 of these are also found in Marianna limestone of Alabama and j 



Florida. 1 



Summary 



The marl at Byram was deposited in warm (tempera- ' 



ture, 2o°-24° C), rather shallow water (depth, 10-25 \ 



fathoms = 18 to 46 meters). Its fauna shows that the larger i 



proportion of the species are closely related to or identical with ; 



those now living in the general Indo-Pacific region. Some of its j 



species have persisted from the lower formations of the lower 

 Oligocene, the Red Bluff clay, the Marianna limestone, and the j 



Mint Spring marl member, while some of them have persisted 

 in the Coastal Plain region, at least into the Miocene. 



