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. Vanuzxemi, (S.G. M.) pl. u. fig. 3, 4. 
American Journal of Science, vol. xviii. pl. 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 costz form distinct, angular prominences. 
Supposed diameter, 3 inches; thickness, 2ths 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 Zurradlites. 
A. A. telifer, (S. G. M.) pl. 11. fig. 7. 
Imperfect as are the remains of this fossil, they indicate a 
species so different from the others, that I venture to give ita 
name. The arrangement of the septa reminds us of the am- 
monite of Maestricht, figured by Faujas, pl. 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- 
viert. 

