PREFACE. Xin 



specimens not in my own or the State collectioti. To several other persons 

 my obligations are also due in particular instances, which are cited in the 

 body of the Work. 



Dr. T. R. Beck, with his characteristic liberality in matters of science, has 

 allowed me free access to the collection of the Albany Institute, which 

 contains many valuable and unique specimens. I have cited, under the 

 descriptions, several specimens figured from this collection, and I shall be 

 further indebted to the same for materials for the next volume. 



To my friends out of the State, who have furnished me with specimens 

 from the same formations, for comparison with those of New-York, my 

 especial thanks are due. Among these I may mention Messrs. Joseph Clarke, 

 J. G. Anthony and S. Carly of Cincinnati, and the Rev. Mr. Christie of 

 Oxford, Ohio, who have liberally forwarded to me many valuable specimens, 

 by the aid of which, in many instances, I have rendered my descriptions 

 and illustrations more complete than I could otherwise have done with the 

 specimens from New- York alone. 



Among the species described and figured, are a few which have not yet 

 been obtained in the State of New-York, but which may hereafter be re- 

 cognized, as more careful investigations are made in the same strata. These 

 8j)ecies are so intimately associated with others which are well known and 

 abundant in this State, that I considered it desirable to represent them in 

 their true place. 



Since this volume has been printed, the Legislature of 1847 have, with 

 munificent liberality, passed a law for the completion of the work, and have 

 authorised 250 plates to be engraved. This number, judging from what I 

 already know of the succeeding strata, will be sufficient for ample illustration 

 of the entire series. 



The succeeding volume will contain the descriptions and illustrations of 

 the fossils of the strata, from the Hudson-river group, up to the Oriskany 

 sandstone inclusive, and will appear in the course of the ensuing year. The 

 remainder will follow as rapidly as may be consistent with accuracy in the 

 determination of their specific characters and geological relations. In the 

 mean time I shall embrace every opportunity of adding to the present portion 

 of the work, by arranging materials as they may come to hand for sup- 

 plementary plates. I shall therefore feel under great obligations to any friend 



