PLEIOCENE FOSSILS. 31 



PBgTEN SEPTENARIUS.— Say. 



Plate XIII., Figs. 1, 2, 3 and 4. 



Pecten Septenarius, Say, Jour. Ac. Nat. Sci., Vol. IV., p. 36, pi. 9, fig. 3. 



P. testa orbicularis convexa, crassa, subceqidvalvi, cequilaterali ; costis 6-7, ampliter, radi- 

 atim striatis, tranversimque decussatis ; intersticiis exeavatis, striatis. 



Description. Shell orbicular, convex, thick, nearly equivalve, equilateral ; ribs 6 to 7, 

 large, radiately striate, and decussated by transverse lines, somewhat squamose ; interstices 

 excavated, striate. 



In young shells the ribs are flat, and angular on the edges, which become rounded as 

 they increase in length with age. The ribs on the umbones are worn smooth ; but towards 

 the pallial margin, both ribs and interstices, are crossed by closely arranged and sharp 

 squamose lines. 



Only a single perfect valve has come into our hands, and this we owe to the politeness of 

 Dr. Harllee, of Darlington District. 



Plate XIII., Fig. 1. Lower valve natural size. 



" 2. Side view of fossil. 



" 3. Magnified view of a portion of a rib. 



" 4. Outline of the form of the ribs at margin. 



Locality. Near Giles's Bluff, Pee Dee. 



Museum, College of Charleston. 

 9 



