Sand Formation of the United States. 279 



One of the most abundant mineral products of these beds is lignite. 

 It is found at the Deep Cut of the Chesapeake and Delaware canal 

 in almost every variety, from charred wood to well characterized jet. 

 Sometimes it is in small fragments, and again it occurs in large 

 masses, representing the trunks and Hmbs of trees thirty feet in 

 length, and perforated in every direction by the teredo. I intimated 

 on a former occasion* the probability that these lignites belonged not 

 to the tertiary deposits, (as in New Jersey, he.) but to the Ferru- 

 ginous sand : this supposition appears now to be still more reasonable, 

 inasmuch as the lignite beds of Delaware are found to be subordi- 

 nate to strata, replete with extinct multilocular univalves, and other 

 secondary reliquiae. 



Synopsis of Organic Remains. 



The following synopsis is designed to present a view of the or- 

 ganic remains hitherto discovered in the American ferruginous sand. 

 The species here enumerated are contained in the valuable collections 

 of the Academy of Natural Sciences ;f others are doubtless preserved 

 in private cabinets, but I here introduce such only as I have seen 

 and examined. 



05^ Nearly all these fossils are described, and many of them figur- 

 ed by me, in the sixth volume of the Journal of the Academy of 

 Natural Sciences ; some are described by Mr. Say, in the first and 

 second volumes of the American Journal of Science ; and Dr. De- 

 kay has also described a number of them in the Annals of the New 

 York Lyceum. 



CHAMBERED UNIVALVES. 



AMMONITES. 



1. A. placenta. (Dekay.) This species (the largest hitherto ob- 

 served in America,) was described by Dr. Dekay from a fragment, 

 and will be found in the second volume of the " Annals of the New 

 York Lyceum of Natural History ."J By some unacountable mistake 

 the description there given refers to the wrong figure in the accompany- 

 ing plate : thus fig. 2, of plate V, is the A. placenta, whereas the 



* Jour. Acad. Nat. Sc. Vol. VI. p. 113. 



t Many of these fossils were presented by Mr. Hugh Lee, Assistant Engineer, em- 

 ployed on the Delaware and Chesapeake Canal, to whom science is under many obli- 

 gations for his zeal in this respect. The same observations will apply to my friend 

 Mr. William L. Newbold, of Delaware city. 



X Vol, II. p. 278. 



