INTRODUCTION. 



xiu 



lications of each one, would occupy more space than the author has at his 

 command in this introduction ; and moreover, few of these writers have pub- 

 lished species from the State of New York. 



The following authors have published descriptions of species of American 

 Palaeozoic Lamellibranchiata : 



During a long interval, after the close of Mr. Conrad's labors, very little was 

 done in New York beyond the accumulation and study of collections, and the 

 determination of specific forms for the illustration of the New York Devonian 

 Lamellibranchiata. 



In 1869, the writer published " Preliminary Notice No. 2 of the Fossil 

 Lamellibranchiate Shells of the Upper Helderberg, Hamilton, Portage and 

 Chemung Groups," etc., to the number of eighty pages, which were issued in 

 December of that year, and one hundred copies in this form were distributed. 

 In January following the printing was resumed, and sixteen additional pages 

 were printed. The pamphlet thus augmented, together with a supplementary 

 page, stating the fact that the descriptions of other species were then in type, 



