196 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



Endopachys maclurii (Lea). 



var. triangular e Conrad. 

 shaleri Vaughan. 1 

 minutum Vaughan. 

 A comparison of this list with the one of the St. Bartholomew 

 and Jamaican corals reveals nothing in common; but I believe it can 

 be made clear that the two faunas are of nearly the same age. That 

 the Jackson formation in Mississippi and Louisiana is a shallow-water 

 deposit is indicated by the nature of the sediments, the growth of 

 specimens of Astrangia on rounded, somewhat indurated balls of 

 sand, such as are common along some beaches, the presence of 

 oyster shells, etc. The striking difference between the Jackson and 

 St. Bartholomew coral faunas is due neither to great difference in 

 geologic age nor to difference in the depth of water in which the 

 faunas lived, but it is due to difference in the temperature of the 

 water. The St. Bartholomew is a tropical fauna; the Jackson is a 

 temperate fauna. 



The correlation of the St. Bartholomew limestone, the Kichmond 

 and Cambridge formations of Jamaica, and the Brito formation of 

 Nicaragua with the Jackson formation of the Gulf States has been 

 made possible by the work of C. W. Cooke and J. A. Cusftman. 

 Cooke shows in the paper cited in the footnote 2 that the Ocala 

 limestone of southern Georgia and Florida is of Jackson age ; and in 

 more recent papers he 3 describes the stratigraphic occurrence, and 

 J. A. Cushman 4 describes the species of the orbitoid genus of foram- 

 inifera Orthophragmina from the Ocala limestone in southern Georgia 

 and Florida. The following is a list of the species: 

 Orthophragmina fiintensis Cushman. 

 floridana Cushman. . 

 americana Cushman, st. 

 mariannensis Cushman, st. 

 mariannensis var. papillata Cushman, st. 

 georgiana Cushman, st. 

 vaughani Cushman, st. 

 Those species whose names are followed by "st. ,, are stellately 

 marked or a,re stellate in form. The Ocala limestone is a shoal-water 

 deposit, laid down in a sea having a tropical temperature. 5 One of 

 the results of my collecting in St. Bartholomew was to find in the 

 St. Bartholomew limestone a stellate species of Orthophragmina, 



1 Name added. _ 



2 Cooke, C W., The age of the Ocala limestone, IT. S. Geol. Survey Prof. Pap. 95-1, pp. 107-117, 1915. 



3 Cooke, C. W., The stratigraphic position and faunal associates of the orbitoid foraminifers of the genu s 

 Orthophragmina from Georgia and Florida, U. S. Geol. Survey Prof. Pap. 108-G, pp. 109-113, 1917. 



* Cushman, J. A., Orbitoid foraminifera of the genus Orthophragmina from Georgia and Florida, U. S. 

 Geol. Survey Prof. Pap. 108-G, pp. 115-124, pis. 40-44. 



6 Vaughan, T. W., A contribution to the geologic history of the FloridiaJi Plateau, Carnegie Inst. Wash- 

 ington Pub. 133, pp. 150-153, 1910. 



