50 CRETACEOUS GROUP 
Cyprma, Lin. 
A solitary cast of a very small species was found in the 
strata of the Chesapeake and Delaware canal, and was 
shown me by Mr. John Finch. 
PATELLA, Lam. 
P. tentorium, (S.G. M.) Pl. i, fig. 11. 
Specific character. Depressed, orbicular, with about eighty 
costiform striz, radiating from the apex to the margin. 
Diameter, rather more than half an inch. 
This fossil has some appearance of a shelly operculum, 
in which case it would belong to the genus Aipponiz. 
I have met with but a solitary individual, which was 
obtained by Mr. Conrad in blue marl, near Arneytown, 
New Jersey. 
ACEPHALA. 
Ostrea, Lam. 
1. QO. falcata, (5. G. M.) PI. i. fig. 5, and pl. ix, 
fig. 6, 7. 
Journ. Acad. Nat. Sciences, vol. vi. pl. i. fig. 2. 
Specific character. Falciform, auriculated, thin, depressed ; 
six or seven deep plications commence near the beaks, and ter- 
minate at the margin. 
Length, from half an inch to an inch and three-fourths. 
A characteristic fossil of this formation; abundant at 
St. Georges, Delaware. Mr. Nuttall found it at Ca- 
hawba, Alabama. It is also very abundant at Prairie 
Bluff, on the Alabama river. | 
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