PREFACE. 



The investigations furnishing the materials for the two papers included in this volume have 

 been carried on by the United States Geological Survey in cooperation with the State geological 

 surveys of South Carolina, Georgia, Alabama, and Mississippi, under the direction of T. Way- 

 land Vaughan, of the United States Geological Survey. 



The correlations with deposits in North Carolina are based on work carried on in that 

 State by the writer from 1905 to 1909, under the auspices of the United States Geological 

 Survey, in cooperation with the North Carolina Geological Survey, and under the immediate 

 direction, during part of the time, of M. L. Fuller, of the United States Geological Survey, and 

 during the remainder under that of Prof. William Bullock Clark, of Johns Hopkins University. 

 In accordance with an agreement with the authorities of the Federal Survey the results of the 

 North Carolina investigations were used in the preparation of a dissertation offered in fulfill- 

 ment of one of the requirements for the degree of doctor of philosophy at Johns Hopkins 

 University. 



Numerous exhaustive collections made, hi 1889 and 1891 by T. W. Stanton, of the United 

 States Geological Survey, from localities in the Atlantic and Gulf Coastal Plain and additional 

 smaller collections in the National Museum made by other investigators have been placed at 

 the disposal of the writer. The fossils collected by Mr. Stanton in Mississippi were determined 

 and listed by him shortly after his return from the field in 1889, and these lists with the accom- 

 panying notes have also been placed at the disposal of the writer. For the assistance thus 

 rendered and for many valuable suggestions and criticisms especial thanks are due to Mr. 

 Stanton. 



The names of the echinoderm species included hi the lists have been furnished by Prof. 

 William Bullock Clark, to whom the specimens were sent for identification. Some of the fish 

 remains mentioned in the text have been identified by Mr. J. W. Gidley, of the National Museum, 

 and all the reptilian remains have been identified by Mr. C. W. Gilmore, also of the National 

 Museum. Indebtedness is acknowledged to these gentlemen for their cooperation. 



During the progress of the investigations the writer has been associated both in the field 

 and in numerous conferences with Mr. E. W. Berry, of Johns Hopkins University, who has been 

 engaged in a study of the fossil plant remains from the Cretaceous beds. Indebtedness is 

 acknowledged to Mr. Berry for numerous annotated lists of plant species and for the many 

 benefits resulting from close association with an investigator of his ability. 



The writer has also been associated in the field and hi conference with Dr. Eugene A. Smith, 

 State geologist of Alabama, and with Mr. Earle Sloan, State geologist of South Carolina, who 

 have spared neither time nor effort hi assisting hi the solution of stratigraphic problems in 

 their respective States. He has also been associated with Mr. Otto Veatch, assistant State 

 geologist of the Georgia Geological Survey, to whom thanks are due for much valuable assistance 

 and also for field notes placed at the writer's disposal. 



The publications of many authors have also been freely drawn upon for information and for 

 field guidance. 



In comparing the Cretaceous faunas of the South with those of New Jersey the writer has 

 relied for his statements as to the range of New Jersey species on the excellent monograph by 

 Stuart Weller, published in 1907 by the Geological Survey of New Jersey, entitled "A report 

 on the Cretaceous paleontology of New Jersey." 



As the investigations progressed the value of the representatives of the genus Exogyra 

 in establishing the major faunal divisions into which the marine Upper Cretaceous deposits of 

 the eastern Gulf region are divisible, and in correlating these divisions with Upper Cretaceous 

 deposits elsewhere in the Atlantic and Gulf Coastal Plain, became more and more apparent. It 

 has seemed appropriate, therefore, to describe the species and varieties of the genus and to note 

 their distribution and range. 



