130 AMERICAN MARINE CONCHOLOGY. 



2. S. NAVALIS, Linnaeus. Figs. 2T5-280. 



Syst. Nat., edit. x. 651. 1758. 



Valves about equal in length and breadth, the posterior auricle 

 expanded somewhat laterally, its base extending lower than that 

 of the anterior area; anterior area moderate, the basal margin 

 convex, inclining somewhat obliquely downwards to the fang, its 

 junction considerably higher up than that of the posterior auricle ; 

 posterior auricle not ascending, but produced laterally, its dorsal 

 edge mostly somewhat concave, lateral margin nearly straight, a 

 little oblique, rounded at each end ; fang acuminating rapidly 

 towards the base ; internally, the apophysis is broad but thin, not 

 thickened at the end, and of the same breadth throughout, and 

 the position of the posterior auricle is defined by a close, project- 

 ing rim ; pallets convex on one side and plane on the other, the 

 stalk, which is about as long as the blade, moderately thick and 

 flexous, not continued as a rib beyond the commencement of the 

 blade ; tube not concamerated. 



Yalves and pallets each 6 mill, in length. 



New England and Middle States. (Eur.) 



3. T. MEQOTARA, Hanley. Figs. 281-283. 



Brit. Conch., i. 77, t. 1, f. 6, t. 18, f. 1, 2. 



Breadth and altitude of valves subequal ; the posterior auricle 

 large, broadly rounded on the margin, raised above the beak and 

 terminating below much further down than the anterior auricle ; 

 the auricle is not defined within by a projecting shelf; pallets 

 spoon-shaped, with truncate apex, with slender, cylindrical stalks, 

 on the concave side forming a rib to the apex of the blade. 



New England. (Eur.) 



4. T. NORVAGICA, Spengler. Figs. 287-291. 



Skrivt., Nat. ii., 102, t. 2, f. 4-6, 1792. 



Yalves solid, higher than wide, the beak elevated beyond the 

 dorsal margins of the auricles ; auricles small, terminating at less 

 than one-half the length of the shell. Pallets spade-shaped, trun- 

 cate at the tip with a stem about as long as the blade ; scarcely 

 defined on the centre of the latter. Tube solid, concamerated. 

 Height 18, breadth 13 mill. 



New England (rare, Eur.). 



This is the largest and most solid species occurring on our 

 coast; its great proportionate length, elevated beaks, and the 



