230 



r.lLsEONTOLOQY OF NEW YORK. 



forms, and all those from the base of the Upper Helderberg to the Chemung, 

 inclusive, are cancellated, or marked only by longitudinal strite. The Bohemian 

 species, which approach those of America in general form, surface-markings, 

 and position of siphuucle, are generally of the curved forms. Of these, several 

 are apparently allie 1 with species described in the present volume, and will be 

 noticed in the comparison of species. 



The number of species of Orthoceratites, including those of the genus or 

 subgenus Endoceuas, heretofore described and recorded from the American for- 

 mations, so far as known to me at the present time, is three hundred and eight, 

 to which will be added in the present volume forty-six species. The species 

 described in the present and preceding publications are distributed in the geo- 

 logical formations according to the following table. 



Of the subgenus Endoceras, twenty-seven species and varieties have been 

 described and recorded ; but all the forms of this type, with a single excep- 

 tion, are restricted to the Quebec group, the Black River and Trenton lime- 

 stones,* and are included in the second column of the table. 



table, is owing to the omission of three synonymic names, and the transfer of 0. acieula to the genus OoLBOLOa. 



