62 Bivalves. — mvtilus. 



yet the greatest proportion of them bear a near alliance 

 to the general form and character of the common or eat- 

 able muscle. There are, indeed, some exceptions, such 

 as may be observed in the Mytilus crista-galli (cock*s- 

 comb oyster), and the Mytilus margaritiferus (true mo- 

 ther-of-pearl shell,) and others of a similar description; 

 most of which give strong evidence of belonging to the 

 ostrea or oyster, rather than Mytilus or muscle genus. 

 However, the hinge seems to regulate the arrangement in 

 most instances, and in the Mytilus it is usually without 

 teeth, having generally a subulate excavated line in place 

 of them. However, some have little denticulations with 

 alternate grooves, whi^h amount in number from ten to 

 fifty in different species* The Mytilus niger has the 

 greatest number of any, viz. one hundred. The Mytilus 

 crista-galli and the like, affix themselves to Gorgonia 

 and other bodies, not by a beard or byssus, as is usual 

 with other muscles, but by a formation of the shell itself, 

 which assumes the appearance of several distinct claws 

 or hands, by which the shell is secured to whatever body 

 it may have selected for its basis. 



The greatest part of this genus exhibit internally a 

 pearly appearance, and some (when uncoated and polish- 

 ed) atford the brightest radiance possible. The Mytilus 

 margaritiferus is renowned for the iridescent colors it 

 displays, and is, moreover, famous for the fine and valu- 

 able pearls it engenders within its silvery valves. The 

 young shells of this species, are sometimes so different 

 to the adults in appearance, that they can scarcely be 

 recognized for the same. Some of this genus posses* 

 the faculty of penetrating and eating away coral-rocks> 

 hard marble, and limestone ; into which they insinuate 

 uud immure thcmj«clvc» so artfullv, that it becomes nc- 



