186 AMERICAN MARINE CONCHOLOGY. 



1. M. edulis, Linnanis. Figs. 474-477. 



Syst. Nat., edit, xii., 1157. 17?7. 

 M. pellucidus, Pennant, Brit. Zool., iv. 237, t. 66, f. 3. 1777. 

 31. notatus, DeKay, Nat. Hist., N. York, 182, t. 13, f. 223. 1843. 



Shell ovate, oblong, beaks pointed, basal margin nearly straight, 

 ligament margin straight ; posteriorly widened and rounded ; 

 hinge with a few dentieulations ; epidermis dark-bluish, smooth, 

 violet beneath ; within white, with a broad blue margin. 



Var. pellucidus, shell horn-color, with blue rays, or uniform 

 horn-color. 



Length 60, height 32.5 mill. 



Whole Coast. (Eur.) 



2. M. exustus, Linnaeus. Fig. 508. 



Mus. Ulric, 540. 

 31. cubitus, Say, Journ. Acad. Nat, Sci., ii. 203. 1822. 



Shell oblong, striated, with elevated subglabrous lines, which 

 are smaller on the anterior side. Yellowish, sometimes blotched 

 with green or brownish. 



Length 28, height 12.5 mill. 



Southern Coast, West Indies. 



3. M. hamatus, Say. Fig. 509. 



Journ. Philad. Acad., ii. 264. 1822. 

 31. stfiatus, Barnes, Am. Journ. Sci., vi. 364. 1823. 



Shell very much contracted and incurved on the basal margin; 

 valves very much striated on every part with radiating elevated 

 lines, which sometimes become bifid or trifid ; color dark fuscous; 

 within purplish. 



Length 28, height 20 mill. 



Southern Coast, W. Indies. 



Genus MODIOLA, Lamarck. 

 Syst., 113. 1801. 



1. M. modiolus, Linnagus. Figs. 510, 511. 



(Mytilus.) Syst. Nat., edit, xii., 1158. 

 31. papuana, Lam., Anim. s. Vert., vii. 17. 

 Mytilus barbatus, Linn., Syst. Nat., xii. 1158 (young). 



Shell large, coarse, and solid, oblong, obliquely dilated ; beaks 

 tumid, obtusely angulated ; basal margin concave, with a fissure 

 for the byssus ; surface coarsely marked by growth-lines; epider- 



