PLEIOCENE FOSSILS. 21 



OSTREA RAVENELIANA.— (New Species.) 



Plate VI, Figs. 1, 2, 3. 



0. testa orbiculata, vel ovata; valva inferiore, convexa, subcostata, lamellosa j valva 

 superiore, lamellosa, maxime depressa, vel concava. 



Description. Shell orbicular or ovate, thin ; lower valve convex, somewhat ribbed, 

 lamellar ; superior valve smooth, lamellar, much depressed, concave ; beaks incurved. 

 This shell is almost orbicular when young, but becomes elongated by age. 



In the Report on the Geology of South Carolina this fossil is cited as 0. dispabilis, Con., 

 which it resembles. It differs from it, however, in being in all stages of growth less 

 robust ; by having the upper valve almost smooth or covered with thin, scarcely raised 

 lamellar plates, and by its greater concavity. 



Inscribed to Dr. E. Ravenel, of Charleston, one of the earliest cultivators of conchologi- 

 cal science in the State, the liberal use of whose cabinet and library no student of science 

 can forget, who has had the good fortune to visit his hospitable residence. 



The genus Ostrea had its beginning in the Triassic, was very numerous in the Jurassic, 

 Cretaceous and Tertiary periods, and has its numerical maximum in the present seas, where 

 it exists at all depths, generally within the limits of tide water, but frequently in deeper 

 soundings. 



Plate VI., Pig. 1. Upper view of fossil, natural size. 

 " 2. Lower valve, from the under side. 

 " 3. Side view. 



Locality. St. John's, Berkeley ; Smith's, Goose Creek ; Grove, Cooper River. 



Museum, College of Charleston, S. C. 

 6 



