568 NORTH AMERICAN INDEX FOSSILS. 



576. L. metastriata Conrad. (Fig. 778.) Cretacic. 



Surface marked with 'fine concentric and coarser radiating ribs, 

 the latter fainter or obsolete on the central portion of the shell. 



Ripleyan of New Jersey (Cliffwood-Red Bank), Gulf region. 



Fig. 778. Linearia metastriata. (N. J. Pal 



CLXVIII. iENONA Conrad. 

 Subtriangular, inequilateral. Beaks very small, pointed. Lunule 

 lanceolate, marked by a deeply impressed line. Two very small, 

 widely divergent cardinal teeth in the right valve, one bifid and one 

 rudimentary tooth in the left valve. Cretacic. 



Fig. 779. ALnona eufaulensis. (N. J. Pal., I.) 



577. A. eufaulensis Conrad. (Fig. 779.) Cretacic. 

 Surface smooth and semipolished. 



Ripleyan of New Jersey (Woodbury), Alabama, Mississippi, 

 Texas. 



CLXIX. Semele Schumacher. 



Large, rounded, thick. Posterior side slightly folded. Both 

 cardinal and lateral teeth present. Pallial sinus large and rounded. 

 Resilifer elongate. External ligament feeble. Tertiary and 

 Recent. 



578. S. carinata (Conrad). Oligocenic-Pliocenic. 

 Concentric lamellae separated by equal or wider interspaces and 



crossed by fine concentric and radial striae. 



Uppermost Oligocenic of Florida (possibly as a variety). Mio- 

 cenic : Maryland-South Carolina. Pliocenic : South Carolina. 



579. S. subovata (Say). (Fig. 780, a.) Miocenic. 

 More oval, thinner than 5. carinata, with finer and closer con- 

 centric striae. 



Maryland, Virginia, Texas. 



