302 [Jan. 17, 



system. It is scarcely possible, on recognising so many of the 

 common organic forms which are familiar to us in connection with 

 the cretaceous rocks on this side of the Atlantic, and seeing them 

 occur in beds which have the exact mineral type of the beds below 

 the Gault, not to feel a strong inclination to regard them as the 

 equivalents of our green sand, and to consider the white chalk as 

 wanting. But when we dismiss from our minds, as we ought to 

 do, the bias derived from the consideration of the mineral aspect 

 of the beds, and compare the fossils of New Jersey with those de- 

 rived from the European chalk, we find the agreement upon the 

 whole to be far greater with the beds occurring in Europe above 

 the Gault, than with those which are found below it. We are 

 indebted to Dr. Morton for having pointed out, in 1834, the general 

 agreement of the organic remains of the American and European 

 cretaceous fossils,' while, and at the same time, he and Mr. Conrad 

 correctly observed that almost all the species were different. He 

 divided the strata of New Jersey into the ferruginous sand, which 

 he compared to our green sand formation, and the calcareous strata, 

 which he identified with the white chalk of Europe. Prof. H. D. 

 Rogers has since divided the New Jersey cretaceous beds into five 

 formations, which are very useful, topographically considered, but 

 which may be overlooked in the present paper, because only two 

 of them, namely, those alluded to by Dr. Morton, have as yet 

 yielded a sufficient number of fossils to entitle them to rank as 

 palgeontologically distinct. 



In an excursion which I made in New Jersey, in September, 

 1841, in company with Mr. Conrad, we went first to Bristol, on 

 the Delaware, next, by Bordentown, to New Egypt, and returned 

 by the Timber Creek, recrossing the Delaware at Camden. On 

 this occasion I had an opportunity of examining the strata of both 

 these formations, and I collected nearly all the fossil species de- 

 scribed by Dr. Morton, together with some few additional ones. 

 I shall now, therefore, briefly notice these two deposits and their 

 fossils, and consider them in reference to their European equi- 

 valents. 



Although in this part of New Jersey there is no white chalk 

 with flints, so characteristic of rocks of the same age in Europe, it 

 is still impossible to glance at the fossils and not be convinced that 

 Dr. Morton was right, as before* hinted, when in 1834 he referred 

 the New Jersey deposits to the European Cretaceous era, and re- 

 marked that the American species of shells were nearly all new 

 or distinct from those before described, and yet very analogous to 

 those of the chalk already known. Of the two well-marked sub- 

 divisions of the Cretaceous system the lower consists in great part 

 of green sand and" green marl, and was supposed by Dr. Morton, as 

 already mentioned, to be the equivalent of the English green sand, 

 while an upper or calcareous rock, composed chiefly of a soft 

 straw-coloured limestone with corals, was thought to correspond 

 with the white chalk of Europe. But after carefully comparing 

 my collection, comprising about sixty species of shells, besides 



