106 PLEIOCENE FOSSILS. 



Description. Shell slightly curved, marked with about thirty-eight very indistinct 

 ribs which become profoundly obsolete towards the base; lines of growth numerous, 

 indistinct; aperture orbicular. 



This species may be readily distinguished by its numerous ribs or strife, which are 

 barely visible to the naked eye, but with a lens are very distinct, 



Plate XXV. Fig. 2, Fossil, natural size; apex broken. 



Locality. Pee Dee. Museum, College of Charleston. 



DENTALIUM THALLUS.-Cor. 

 Plate XXV. Fig. 3. 



Dentalium thallus, Con., Jour. Acad. Nat. Sci., Vol. 7, p. 142. 

 Dentalium thallus, Con., Foss. Med. Ter., p. 78, pi. 44, fig. 5. 



D. testa rnodice curvata, lavi, perpolita, inframedium tumida, versus basim paullatim 

 coarctata; apertura ovali.. 



Description. Shell slightly curved, smooth, highly polished, tumid below the middle 

 and gradually contracting towards the base; aperture oval. 



Common in the Meiocene of Virginia and the Pleiocene of North and South Carolina. 



Plate XXV. Fig. 3, Fossil, natural size. 



Locality. Pee Dee. Museum, College of Charleston. 



The genus dentalium commenced its existence in the seas of the Devonian period. 



