56 POST-PLEIOCENE FOSSILS. 



and having a tooth-like process, distinct and prominent behind; muscular and pallial 

 impressions simple, the latter indistinct. 



This small species is readily distinguished by its sub-equal posterior and anterior 

 margins, the anterior being narrowest ; beaks not prominent forward of the middle, and by 

 the prominent tooth-like process of the right valve; it differs also from M. arenaria, in 

 having the anterior muscular impression simple, and not club-shaped. 



Not known to exist in the recent state. 



Plate VIII. Fig. 16. 



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



Genus, CORBULA.— Brug. 



COKBULA CONTEACTA. 

 Plate VIII. Fig. 17. 



Corbula contracta, Say, Jour. Acad. Nat. Sci., Vol. 2, p. 312. 



Corbula contracta, Ravenel, Cat. Coll. Shells, p. 3. 



Corbula contracta, Gould, Invert. Mass., p. 43. 



Corbula contracta, L. R. Gibbes, Tuomey's Geol. So. Ca., appendix, p. xxii. 



Description. Shell transversely sub-ovate; valves sub-equal, regularly and profoundly 

 striated transversely ; beaks not prominent, nearly central, one side rounded and the other 

 sub-acute; basal margin contracted near the middle, one half of the length of one valve 

 concealing one half of the edge of opposite valve. — Say. 



I have not seen a living specimen, though the shells are common along the beaches of 

 the Southern sea-coast. 



Plate VIII. Fig. 17, Shell, natural size. 



Locality. Simmons'; Abbapoola; Charleston, Artesian Well. 



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



