OF THE UNITED STATES. 41 



it is accompanied by Gryphjea vomer, G.. Pitcheri and 

 Exogyra costata. It is allied to A. JDelawarensis, but 

 differs in tbe absence of bifurcations in tbe costse. 



Scaphites, Parkinson. 



S. hippocrepis 7 p , ^. fi 



S. Cuvieri, (S. G. M.) 3 ° 



Ammonites hippocrepis, (Dekay.) 

 Annals of the New York Lyceum, vol. ii. pi. v. fig. 5. 



Specific character. Larger ichorl ventricose, with eight pro- 

 minent lateral tubercles, and two others more elevated at the 

 inner margin on each side ; back delicately ribbed between 

 the lateral tubercles ; an obscure ridge from each of the latter 

 to the umbilical margin ; no visible septa : smaller ichorl com- 

 pressed, half concealed, costated all round ; septa numerous, 

 serrated like those of an Ammonite.* ' 



Diameter of larger whorl, an inch and a half. 



Diameter of smaller whorl, an inch and an eighth. 



This beautiful specimen is a black sub-siliceous cast : 

 it was found about sixty feet below the surface, at the 

 deep cut of the Chesapeake and Delaware canal, in an 

 argillo-ferruginous sand. 



This fossil was obligingly presented to me by my friend 

 Mr. Wm. L. Newbold, to whom I am under many simi- 

 lar obligations. 



Dr. Dekay first described this fossil from an imperfect 

 fragment, and caHed it Ammonites hippocrepis. Seve- 

 ral years afterwards, I satisfied Dr. Dekay that we had 



* S. anfractu majori ventricoso, tubereulis octo in utroque latere, cum duobus 

 alteris prope marginem internam ; dorso pulchre costato inter tuberculas : an- 

 fractu minori compresso, costato, semi occultato ; septis serratis. 



