244 Organic Remaitis of the Ferruginous 



these relate to the calcareous deposits embraced in the marl district 

 of New Jersey. 



These calcareous beds were first noticed, during the past year, in 

 Gloucester county ; more recently they have been found to have a 

 much wider range, and are now traced for several miles in Burlington 

 county, not far from Vincentown, where they possess precisely the 

 same mineralogical and organic characters as the beds of Gloucester. 

 Some specimens I have examined from the southern part of the pen- 

 insula, in the vicinity of Salem, lead me to the conclusion that the 

 same formation exists there. It seems probable, therefore, that the 

 calcareous strata extend, with occasional interruptions, nearly fifty 

 miles, in a direction parallel to the course of the Delaware river, and 

 from seven to ten miles east of it. 



A gentleman who has recently examined some of these localities, 

 informs me that he found the beds in question resting on the common 

 green and blue marls ; an important fact, inasmuch as it proves that 

 our calcareous and arenaceous strata have the same relative position 

 as the chalk and green sand of Europe ; a circumstance much en- 

 hanced by the collateral fact that similar genera of fossils characterize 

 the deposits on both sides of the Ariantic, as will be seen by refer- 

 ence to the former part of this synopsis. 



The following list embraces the remaining marl fossils, and com- 

 pletes the hst of those hitherto identified. 



CHAMBERED UNIVALVES. 



AMMONITES. 



Two species have already been noticed, and three remain to be 

 added. 



3. A. delawarensis. (S. G. M.) Found in the lower beds of the 

 Chesapeake and Delaware Canal ; fragments only have been obtain- 

 ed, the most perfect of which is figured on the annexed plate. 



4. A. Vanuxemi. (S. G. M.) Occurs with the preceding, but is 

 as yet a rare species. 



5. Fragments of a fifth species are contained in the collections of 

 the Academy, but are too imperfect for description. 



SIMPLE UNIVALVES. 



PATELLA. Lam. 

 A small species, half an inch in diameter, and delicately ribbed. 



