22 POST-PLEIOCENE FOSSILS. 



ribs about thirty-five, nodulous in the light valve of young shells; in the left, only those 

 on buccal side are thus ornamented. 



A. TRANSVERSA Is now living on the coast, and is found fossil in the Meiocene of Vir- 

 o-inia, Pleiocene and Post-Pleiocene of South-Carolina. 



Plate IV. Fig. 5, Shell, natural size. 

 " 5a, hinge view. 



Locality. Simmons'; Doctor's Swamp, John's Island; Hamblin's, Christ Church. 



Museum, College of Charleston; Cabinet F. S. H. 



A R C A C .E L A T A . 



Plate IV. Figs. 6 and 6a. 



Area cffilata. Con., Foss. Ter. Form., p. 61, pi. 32, fig. 2. 



Area cselata, Tuomey Sf Holmes, Pleiocene Foss. 'So. Ca., p. 36, pi. 16, figs. 8 to 10. 



Description. Shell trapezoidal; disk widely and not profoundly contracted; ribs 

 numerous, alternated towards the base, tuberculated, aculeated anteriorly and posteriorly ; 

 posterior slope depressed ; umbo acutely angulated behind ; basal margin slightly arched ; 

 posterior margin obliquely truncated; beaks approximate. — Con. 



This species is rare in the recent state on the coast of South-Carolina, but is a common 

 fossil in the Post-Pleiocene beds. 



It is a beautiful little shell, much ornamented by its nodulous radiating striae. 



Plate IV. Fig. 6, Shell, natural size. 

 " 6a, Hinge view. 



Locality. Abbapoola Creek, John's Island. 



Museum, College of Charleston; Cabinet F. S. H. 



