BIVALVES. 3IVTILUS, 63 



cessary to break the stone before there is a possibility 

 of withdrawing the shell and its inhabitant. Of this 

 description are the Mytilus litho])hagus and rugosus. 

 The latter is sometimes found in lakes as w ell as seas. 



There are some muscles, w Inch, on a superficial glance, 

 might be mistaken as belonging to the genus Mya; such 

 are the Mytilus versicolor, discors, and afer; but, by a 

 minute inspection of the hinge, the error would soon be 

 discovered. The general appearance of muscles differs 

 greatly, some being perfectly smooth, and beautifully 

 marbled and variegated with fine coloring; others are 

 elegantly radiated with purple and white, like a tulip; and 

 some again are coarsely ribbed and grained with minute 

 tubercles, making the shell quite rough, and of one color 

 oidy, such as black, blue, green, yellow, and brown. 

 But they are most of them indebted to their epidermis 

 for whatever outward color they may possess; which, 

 w hen removed, often presents so different a surface, that 

 even an adept might be puzzled to recognize two shells 

 of the same species. Some of the cuticles or skins are 

 often bearded or shaggy, and, in some instances, tiie valves 

 gape,as in the Mytilus bilocularis,and other similar species. 

 However, almost the whole of the different species of 

 muscles, seem to accord with the habits of the common 

 or eatable muscle (Mytilus edulis), which invariably af- 

 fixes itself to other bodies, by means of its silky byssus; 

 and is found in immense beds or layers, consisting of 

 many myriads. 



The Mytilus cygneus and anatinus, (both fresh-water 

 species), frequently become the food of ducks and crowg; 

 the latter of which, when they find the shell too hard, 

 mount with it into the air, and then IcKing it lall, they 

 pick out the fish from the broken siicll. 



