PREFACE. 



The present condition of the paleontology of the Tertiary Formation is 

 so much confused that it has been found quite impossible to make a com- 

 plete and accurate report at this time ; therefore, simply as a beginning, 

 the writer has prepared the following descriptions and lists. 



No attempt has been made to correct the nomenclature ; in general, the 

 name under which a species has been described, is used, sometimes that of 

 Conrad, and often that of Lea, without attempting to decide questions of 

 priority. 



Again, many. species are described without figures, and in others the 

 descriptions are so vague or figures so poor, it has been found out of ques- 

 tion to identify from them alone. The writer hopes to correct, as far as 

 possible from the types these uncertainties, and in a final report to bring 

 the subject up to date. In these tables or lists where a species could not 

 be definitely ascertained, no specific name is given ; where the identifica- 

 tion is at all doubtful, the specific name is followed by a question mark, 

 and where a species is believed to be new, it is so indicated. 



At present the collections in hand have not been sufficiently examined 

 to report upon the Claiborne ferruginous sand-bed proper, the Jacksoir 

 and Vicksburg Groups. These are reserved for the future. 



Plates 1 and 2 were published in the Journal of the Cincinnati So- 

 ciety of Natural History, Vol. VIII., July, 1885, but as several 

 changes are necessary, they are inserted here. 



The writer is greatly indebted to Prof. Angelo Heilprin, of Phila- 

 delphia Academy of Natural Sciences; Prof. R. P. Whitfield, of the 

 American Museum, New York ; and Dr. Otto Meyer for identifications 

 and critical remarks. To Dr. C. A. White, of the U. S. Geological 

 Survey for the loan of types; and more especially to Dr. Eugene A. 

 Smith for the opportunity to make the collections from which this paper 

 is prepared. 



