186 AMERICAN MARINE CONCHOLOGY. 
1. M. eputis, Linneeus. Figs. 474-477. 
Syst. Nat., edit. xii., 1157. 1757. 
M. pellucidus, Pennant, Brit. Zool., iv. 237, t. 66, f. 3. 1777. 
M. notatus,, DeKay, Nat. Hist., N. York, 182, t. 13, f. 223. 1848. 
Shell ovate, oblong, beaks pointed, basal margin nearly straight, 
ligament margin straight; posteriorly widened and rounded; 
hinge with a few denticulations; 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. (Hur.) 
2. M. Exustus, Linneus. Fig. 508. 
Mus. Ulric., 540. 
M. cubitus, ‘Say, Journ. Acad. Nat. Sci., ii. 268. 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. HAMaATUS, Say. Fig. 509. 
Journ. Philad. Acad., ii. 264. 1822. 
M. striatus, Barnes, Am. Journ. Sci., vi. 864. 1823. 
Shell very much contracted ial incurved on the basal margin ; 
valves very much striated on every part with radiating alewated 
lines, whick sometimes become bifid or trifid; color dark fuscous ; 
within purplish. 
Length 28, height 20 mill. 
Southern Coast, W. Indies. 
Genus MODIOLA, Lamarck. 
Syst., 118. 1801. 
1. M. Moproxus, Linneeus. Figs. 510, 511. 
(Mytilus.) Syst. Nat., edit. xii., 1158. 
M. 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- 
