TO 



SAMUEL GEORGE MORTON, M. D. 



MKMUEIl OF THK AMERICAN PHILOSOPHICAL BOCIETY, 



COUUKSPONMNO SECKETAUY OK THE ACADEMY OF NATUltAL SCIENCES, OF 

 PHILADELPHIA, &C. 



In publishing the fossil shells of our Tertiary formations, it 

 is a pleasure as well as a duty to inscribe to you a work, which, 

 whatever its merits, would not have appeared without your en- 

 couragement and assistance. Your zeal for establishing the 

 Geology of our country on its only permanent basis, organic 

 remains, has added a valuable series of American fossils to 

 the splendid collections of the Academy of Natural Sciences, 

 to which I owe the opportunity to figure and describe nearly 

 all the species illustrated in the following pages ; but I sin- 

 cerely regret that your professional duties are too arduous to 

 permit you to underta'ke a work for which you are so much 

 better qualified than myself; for, with such ample materials, 

 you could not have failed to render it acceptable both to the 

 Geologist and the student in Conchology. 



T. A. CONRAD. 



|18J 



