PnOLADIDj;. 57 



Genus, SAXICAVA. — Fleuriau de Bellevue. 

 Genus, BYSSOMYA.— Cuv. 



SAXICAVA F R A G I L I S . — (New Species.) 

 Plate VIII. Fiu. 18. 



Description. — Shell oblong, fragile, concentrically striated, somewhat laminated; 

 anterior and posterior margins obtusely rounded; dorsal margin straight, or slightly curved 

 towards posterior end; pallial margin compressed in the middle; umbones anterior, 

 depressed ; pallial impression distinct, simple, at a distance from margins ; cardinal tooth 

 in both valves, prominent, nodulous. 



We have the right and left valve of this shell from the Post-Pleiocene ; it is not known 

 on the coast. 



Plate VIII. Fig. 18, Right valve, natural size. 



Locality. Simmons'. Cabinet F. S. H. 



Genus, P H O L A S. — L i n n. 



PHOLAS TRUNCATA. 

 Plate IX. Fig. 4. 



Pholas truncata, Say, Jour. Acad. Nat. Sci., Vol. 2, p. 223. 



Pholas truncata, De Kay, Zool. New- York, Art. Mollusca, p. 248, pi. 34, fig. 223. 



Pholas truncata, Ravenel, Cat. Coll. Shells, p. 2. 



Pholas truncata, L. R. Gibbes, Tuomey's Geol. So. Ca., appendix, p. xxii. 



Pholas truncata. Say's Conch. U. S., (Binney,) p 107. 



Description. Shell transversely oblong, sub-pentangular; anterior margin rostrated, 

 obtusely cuneiform in the middle; posterior margin broadly truncated at tip; valves 

 transversely wrinkled and longitudinally striated, muricated, particularly on the anterior 

 side, with small erect scales, which are not arched beneath; posterior margin from a line 

 extending from the beak to the inferior angle of the truncature, destitute of the striae and 

 mutic; hinge callous, formed of the duplicature of the hinge-margin, and destitute of 

 cells ; a small tooth upon the inner margin, projecting backwards ; dentiform process 

 curved, prominent, slender, flat. — Say. 



Plate IX. Fig. 4, Shell, natural size. 



Locality. Simmons'. Museum, College of Charleston; Cabinet F. S. H. 



15 



