18 INTRODUCTION. 



The greatly extended Tertiary deposits on the Atlantic 

 coast of our country, present one of the most interesting 

 of the geological phenomena known in it. To ascertain 

 the relative age of the deposits of the same formation in 

 Europe, has engaged the attention of the fossil concholo- 

 gist there for many years. With us, partial examinations 

 of the fossils of the different beds, have already been made 

 by several of our geologists. In the course of my inves- 

 tigations, I have satisfied myself of the identity of our 

 Tertiary Formation with that of Europe. 



After a careful examination of a great number of genera 

 and species, from the Tertiary of Claiborne, Alabama, I 

 had no hesitation in referring them to the same period as 

 the London Clay of England and the Calcaire Grossier 

 of Paris ; although this deposit is composed of silicious 

 sand, while that of the London Clay is argillaceous, and 

 the Calcaire Grossier is calcareous. This part of the Ter- 

 tiary Formation, as before stated, is called by Mr Lyell, the 

 Eocene Period. It abounds in the greatest variety of 

 fossils ; one thousand two hundred and thirty-eight species 

 of shells having in Europe, as before mentioned, been 

 noticed in it. I have already observed nearly two hundred 

 and fifty species from Claiborne, descriptions of two hundred 

 and nineteen of which being supposed to be new, will be 

 found in their proper order, in this memoir and its supple- 

 ment.* It is an extraordinary fact, that among the whole 

 of these, there cannot be, with absolute certainty, a single 

 species found to have its analogue in a living species. Some 



* Mr Conrad has described twenty-five species. See Fossil Concho- 

 l gyj Nos. 1 and 2, and the American Journal of Science and Arts, vol. 

 23, p. 339. 



