109 
Grnus.—MYTILUS. 
Longitudinal, equivalve, acute at the base, usually 
affixed by a byssus ; beaks acute, somewhat straight 
and terminal ; hinge lateral and usually toothless, 
ligament marginal and subinternal; scar elongated, 
- clavate, sublateral. 
M. Epuuis. Lin. 1157.—Ch. f. 750.—Pen. 4. p. 
236. ¢. 66. f. 2.—Don. 4. t. 128.—Mont. p. 159.— 
Tin. T. 6. t. 18. f. 13,4.—Dor. Cat. t. 12. f. 5.1. hand. 
—D. p. 309.—Turt. D. p. 109.—Da. Cost. t. 15. f. 
5. l. hand.—-H. t. 218. f. 2.—Knorr. 4. t. 15. f 1.— 
F. p. 411.—Oval-oblong, smooth, posteriorly tumid 
towards the beaks, curved and somewhat carinate ante- 
riorly, rich blue under the epidermis; beaks blunt; 
hinge with four or five teeth. 2. Common Muscle. 
* An var. M. Sussaxatitis. Williams in Mag. 
Nat. 7. p.354.—An. M. Gatioprovinetatis? Lam. 
—Strong, solid, the hinge line longer and very straight, 
thus forming a more or less distant angle with the ven- 
tral edge. I believe it to be a distinct species. 
* When beween rocks the posterior edge becomes 
concave. — 
