56 MYAD^. 



irregularly wrinkled ; beaks small, pointed, slightly curved for- 

 wards, directly under wliicli, in the left valve, rises an erect tooth, 

 rounded at its summit, of about equal breadth and height; its 

 inner face is smooth and rounded ; its outer face is divided into 

 two portions, the largest of which is spoon-shaped, the other flat 

 and traversed across the middle by a grooved ridge which projects 

 beyond the margin of the tooth like a smaller tooth ; on the right 

 valve we have a deep excavation imbedded in the cavity of the 

 beak ; in this and in the concave portion of the tooth is fixed the 

 very strong cartilage ; anterior nuiscular ini})ression narrow and 

 long, club-shaped ; posterior one semi-oval ; pallial impression scal- 

 loped along the base, and very deeply notched behind. Common 

 length, three and one half inches ; height, two inches ; breadth, 

 one inch. I have a specimen, the corresponding dimensions of 

 which are five and one half, three and four tenths, two and one 

 tenth inches. 



This shell (the Clam, not of New York and Philadelphia) is fa- 

 miliar to every one wlio resides on the sea-coast. It is always 

 to be seen in every market, and f)n every quiet shore. Its resi- 

 dence is always between high and low tide, or in such places as 

 allow it to be partially exposed to the air a part of the time. Such 

 are our sandy beaches, muddy inlets, and mouths of streams emp- 

 tying into the sea, &c. It usually lies just below the surface, and 

 over it is a round hole through Avhich the animal occasionally 

 ejects a jet of water to a considerable height above the sand ; and, 

 if the shallow water is observed where they are known to dwell, 

 it will be perceived to be kept in constant eddies by the suction 

 and ejection of the water. 



There seems to be no character which affords any ground for 

 separating our shell from the Euro])ean clam. Mr. Say, as he 

 merely refers to Pennant's figure, had prolialdy never seen a speci- 

 men from across the Atlantic. A comparison would certainly 

 have saved him from the error of describing it as a new species. 

 Nor can I believe there is any occasion to make two species, the 

 mercenaria and acuta, as he has done. His acuta was formed 

 from a specimen in which the posterior extremity was very acute; 

 but in this part we find great diversity of proportions in different 

 specimens. It is found far up the St. Lawren(?e River, where it 

 grows smaller and smaller, as it always does in ]n"oj)ortion to anj- 

 admixture of fresh water. It is found along the whole coast of 

 Nova Scotia ( Willis) and Labrador (^Packard) ; Cape Hope, James's 



