VI PREFACE. 



the American Journal of Science and Arts, in January of the succeeding 

 year.* 



In consequence of the facilities afforded me for this inquiry, several 

 genera of organic remains are now noticed for the first time as occurring on 

 this continent ; and it will be observed that two new genera and many new 

 species of Testacea have been added to this edition. 



I may add, that up to the present time eight only of the fossil shells and 

 zoophytes noticed in this work have been described, and but four of them 

 figured by other naturalists. 



I have endeavoured, in this edition, to correct the inaccuracies of my for- 

 mer papers, and good artists have been employed to furnish the accompany- 

 ing illustrations, consisting of nineteen plates, and one hundred and sixty 

 figures, which almost without exception, possess the merit of great accu- 

 racy. The care bestowed on these illustrations, precludes the necessity of 

 those minute specific details in the text, which would have been otherwise 

 indispensable. 



Philadelphia, January 1st, 1834. 



* Vols. XVII and XVIII ; plates in the latter volume : my other papers, also 

 illustrated by plates, will be found in Vols. XXII, XXIII and XXIV ; and in 

 Journ. Acad, of Nat. Science, Vol. VI, from 1827 to 1830. 



