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interesting work devoted expressly to the subject, by Dr. S. G. 

 Morton, of Philadelphia. This highly esteemed contribution to 

 our geology, is entitled " Synopsis of the Organic Remains of the 

 Cretaceous Group of the United States," — 1834. 



To that source I must refer for much specific information 

 respecting the individual fossils of the greensand group. I may 

 be allowed, however, to indulge in a few generalizations calcu- 

 lated to impart more correct notions than commonly prevail 

 respecting the nature of the fossils, and the relative age and origin 

 of the strata in which they are imbedded. 



There have been found up to the present time, in the marl and 

 the deposits connected with it, relics of about seventy-five extinct 

 species, chiefly marine; of these, at least seven are of the class 

 of large reptiles, including three species of crocodile ; two of 

 fishes; a tortoise, and a wading bird; upwards of sixty-five are 

 remains of shell-fish, corals, and other tribes low in the scale of 

 organised beings. It is a curious fact, that not one of the fossils 

 of this catalogue can be traced to belong to any species living in 

 the present day ; and it is a scarcely less interesting circumstance 

 that between these fossils and the organic remains of the most 

 nearly related strata of Europe we discover but one species, 

 the Pecten Quinquecostatus, common to the deposits of both con- 

 tinents. 



The first fact determines the place of the marl group to be 

 somewhere among the secondary rocks, and the generic affinities 

 of the fossils to well known fossils of the greensand and chalk 

 formations of Europe, makes us naturally regard that part of the 

 secondary series as the most probable place to which to refer 

 them. The striking want of identity between the species, renders 

 it, however, a question of much uncertainty, to what precise for- 

 mation of the secondary series of Europe these deposits strictly 

 correspond. 



To refer the production of the marl strata of New Jersey to 

 the same period which produced the greensand rocks of Europe, 

 merely in consequence of their both containing the green granu- 

 lar mineral, and to their having, moreover, a general resemblance 

 in their fossils, is to commit the decision of the question to far too 

 loose a mode of reasoning. Received principles of geological 

 investigation require us rather to consider our own deposits as 



