140 AMERICAN MARINE C0NCH0L0GY. 



torior side ; cartilage process spatulate, in each valve, with an obsolete 

 tooth in front, and a posterior lateral tooth ; pallial sinus very shallow. 



Ne^ra. 



Genus MYA, Linnaeus. 

 Syst. Nat., edit. x. 670., 1758. 



The animal has a small, straight, linguiform foot; the siphons 

 are combined and covered with a partially retractile epidermis ; 

 orifices fringed, branchial opening with an inner series of large 

 tentacular filaments ; gills not prolonged into the siphon ; palpi 

 elongated, free. 



About ten species are known, of universal distribution. They 

 are found in sand or mud, especially estuaries, and ranging, gene- 

 rally, from low water to 25 fathoms. Our species are edible. 



1. M. arenaria, Linnaeus. Fig. 322. 



Syst. Nat,, edit. xii. 1112. 1767. 

 Mya acuta, Say. Journ. Philad. Acad., ii. 313. 1822 (Young). 

 Mya merceriaria, Say. Ibid. 



Shell transversely ovate, subequilateral, convex, gaping at both 

 ends, but more so at the posterior end, where the valves curve 

 outwards. Beaks small ; epidermis rough, wrinkled, yellowish. 

 Length 3 to 5 inches, height 1.5 to 2 inches. 



Inhabits the Whole Coast. (Eur.) 



Common everywhere, burrowing in sand between high and low 

 water ; its residence is readily detected by a small aperture in the 

 sand, through which it ejects a stream of water upon treading hard 

 on the surface. On many parts of Long Island the hogs are accus- 

 tomed to root for this species, and follow the tides with uuerring 

 sagacil}'. 



2. M. truncata, Linnaeus. Figs. 320, 325 (animal). 



Syst. Nat., edit, xii. 1112. 1767. 



Shell subquadrate, truncated behind, where it gapes widely ; 



basal margin irregularly sinuous; epidermis tough and corrugated ; 



tooth broader than long, with a slightly thickened lobe on the edge; 



valves convex, beaks moderate^ prominent ; epidermis yellowish. 



Length 2.5 to 3.5 inches, height 1.5 to 2.5 inches. 



Northern Coast. (Eur.) 



Externall}', this common species resembles the Panopaea arctica, 

 but is readil3' distinguished by its spoon-shaped tooth. 



