MY AC ID M. 55 



Genus, MYA. — Linn. 



M Y A A E E N A E I A . 



Plate YIIT. Fig. 15. 



Mya arenaria, Linn., Syst. Nat,, p. 1112. 



Mya arenaria, Gould, Invert. Mass., p. 40. 



Mya mercenaria, Say, Jour. Acad. Nat, Sci., Vol. 2, p. 313. 



Mya acuta, Say, Jour. Acad. Nat. Sci., Vol. 2, p. 313. 



Mya acuta, Say's Conch. U. S., (Binney,) p. 103. 



Description. Shell transversely ovate, equivalve, sub-equilateral, tumid, gaping at 

 both ends, surface wrinkled; anterior margin rounded; posterior margin produced, sub- 

 acute, reflexed, without teeth ; process for cartilage-pit in left valve large, of equal length 

 and breadth, and projecting inwards and backwards ; cartilage-pit of right valve without 

 a process, but with a tooth-like projection behind it ; its anterior margin reflexed; anterior 

 muscular impression narrow, long, club-shaped, extending upwards towards the beaks- 

 pallia! impression distinct, irregularly scolloped ; pallial sinus deep and broad. 



Mya arenaria is the long clam of the Boston and New-York markets, and does not 

 exist on the coast of the Southern Atlantic States. The clams of the Charleston market 

 are Venus mercenaria, and Venus Mortoni. The Myas found upon our beaches are 

 undoubtedly fossils of the Post-Pleiocene, and this we infer not only from their old and 

 water-worn appearance, but from Mr. Say's description of his species "acuta," which he 

 says was from this coast. Like "M. acuta," our fossil is more acutely pointed posteriorly 

 than the recent shell. 



Plate VIII. Fig. 15, Valves, natural size. 



Locality. The beaches of the coast ; Simmons'; Abbapoola, &c. 



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



MYA SIMPLEX. — ( New Species.) - &J <s**JJU^ ^ , 

 Plate VIII. Pic. 16. 



Description. Shell transversely ovate, convex, not tumid, inequilateral, concentrically 

 striated; anterior and posterior margins obtusely rounded, the former narrowest ; pallial 

 margin sub-rectilinear ; posterior dorsal margin slightly curved ; cartilage-pit excavated, 



