38 CRETACEOUS GROUP 



margin ; ridges marked by three or four conspicuous nodes ; 

 back between the tubercles convex. 



Probable diameter from 8 to 12 inches. 



The annexed drawing is from a specimen obtained at 

 the Delaware and Chesapeake canal, in the Ferruginous 

 sand. I have another from Alabama. 



3. A. Vanuxemi, (S. G. M.) pi. ii. fig. 3, 4. 

 American Journal of Science, vol. xviii. pi. iii. fig. 3, 4. 



Specific character. Whorls depressed, sub-convex, with 

 numerous slightly curved, tuberculated ribs ; back marked with 

 a single, prominent, central ridge, on each side of which the 

 terminations of the costae form distinct, angular prominences. 



Supposed diameter, 3 inches ; thickness, f ths of an inch. 



Found at the Chesapeake* and Delaware canal. Hitherto 

 fragments only have been obtained, the most perfect of 

 which is figured on the annexed plate. Larger speci- 

 mens have been found. 



I have much pleasure in dedicating this species to my 

 friend Mr. Lardner Vanuxem. 



This may prove a turrited shell, in which case it will 

 of course be transferred to the genus Turrilliies. 



4. A. telifer, (S. G. M.) pi. ii. fig. 7. 



Imperfect as are the remains of this fossil, they indicate a 

 species so different from the others, that I venture to give it a 

 name. The arrangement of the septa reminds us of the am- 

 monite of Maestricht, figured by Faujas, pi. xxxi. 



In the former edition of this synopsis, I admitted the 

 .Ammonites hippocrepis of Dekay : I have lately, through 

 the kindness of, that gentleman, examined his specimen, 

 and find it to be a transverse fragment of Scaphites Cu- 

 vieri. 



