94 PLEIOCENE FOSSILS. 



Description. Shell sub-orbicular, ventricose, smooth; beaks sub-medial nearest to anal 

 end; umbonial slope sub-marginal, slightly carinated; anal side somewhat warped or bent. 



This is a common recent species on the shores of South-Carolina, Florida, and Alabama, 

 and fossil in the Post Pleiocene of this State. 



Plate XXIII. Fig. 3, Exterior of valve, natural size. 



Locality. Smith's, Goose Creek; Waccamaw. 



Museum, College of Charleston. 



AMPH-IDESMA ORBIClfLATA. — Say. 



Plate XXIII. Fig. 4. 



Amphidesma orbiculata, Say, Jour. Acad. Nat. Sci., Vol. 2, p. 307. 



A. testa orbiculari, sub-compressa, lineis concentricis tenuiter striata; his a laminis elevatis 

 concentricis irregulariter interrupts; margine buccali obtuse undulata; fovea ligamentali 

 profunda, fusif or mi, usque adumbonis apicem excavata. 



Description. Shell orbicular, sub-compressed; surface finely marked with concentric 

 lines of growth, which are interrupted irregularly with raised sub-laminated concentric 

 lines; buccal margin obtusely undulated; interior ligamental cavity profound, fusiform, 

 parrallel with marginal slope, and extending from tip of beak. 



In young shells, longitudinal, radiating, and obsolete lines are distinctly seen intersect- 

 ing the lines of growth, but in older specimens a few lines only are visible upon the buccal 

 folds or undulations. 



This species is abundantly fossil in the Post Pleiocene, and is recent on the coast of the 

 State. 



Plate XXIII. Fig. 4, Interior and exterior of shell. 



Locality. Waccamaw. • Museum, College of Charleston. 



