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PALEONTOLOGY OF NEW YORK. 



ness, but of a less calcareous character, has afforded nineteen species ; while the 

 Waverly, the Lower Carboniferous limestones and the Coal Measures have 

 recorded seven, eight and eight species respectively. 



So far as we now perceive, the development of the Orthoceratites does not 

 depend upon the duration of the deposition, or thickness of the formation. The 

 Black-river limestone, of a few feet in thickness, and the Schoharie grit, of not 

 more than thirty feet in thickness, have each as many species of Orthoceras re- 

 corded as any single group, except the Hudson-river, Niagara, and the Hamilton. 



The following table shows the vertical distribution of eighteen species of the 

 preceding table, which are known to occur in more than one geological formation : 



