44 POST-PLEIOCENE FOSSILS. 



Genus, MESODESMA.— Desh. 



MESODESMA CONCENTRICA.— ( Neio Species.) 

 Plate VI. Fig. 10. 



Description. Shell small, trigonal, thick, very inequilateral, concentrically and finely 

 ribbed ; ribs regularly rounded ; anterior margin rounded regularly, deeper than posterior; 

 anal margin slightly compressed in the middle; posterior extremity of shell prolonged, 

 narrowed, wedge-shaped. 



This shell closely resembles Mesodesma arctata, Gould; the anterior extremity is 

 not truncated, but regularly rounded; the concentric strife, or finely rounded ribs, are 

 quite characteristic ; I have found a few shells in the sands of our sea-beaches, but none 

 with the animal. 



Plate VI. Fig. 10, Natural size. 



Locality. Simmons'; St. Paul's. Cabinet F. S. H. 



Genus, TELLINA.— Linn. 



TELLINA FLEXUOSA. 

 Plate VII. Fig. 14. 



Tellina flexuosa, Say, Jour. Acad. Nat. ScL, Vol. 2, p. 303. 

 Tellina flexuosa, Be Kay, Zool. New- York, Art. Mollusca, p. 210. 

 Tellina flexuosa, L. R. Gibbes, Tuomey's Geol. So. Ca., appendix, p. xxi. 

 Tellina flexuosa, Tuomey $ Holmes, Pleiocene Foss. So. Ca., p. 90, pi. 22, fig. 7. 



Description. Shell sub-orbicular, surface obliquely sculptured, with very regu- 

 lar parallel lines; longitudinal striae none; transverse wrinkles minute; buccal margin 

 longer than anal, and less obtusely rounded; beak placed behind the middle, not 

 prominent. — T. <%■ H. 



This shell is often found in the sands of our sea-coast. 



Plate VII. Fig. 14, Natural size. 



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



