188 BIVALVES. 



Genus MYTILUS.* Plural, Mytili. 



MUSCLE. 



Generic Character. Shell bivalve, rough, 

 generally affixed by a byssus to marine sub- 

 stances ; shape generally a long oval, sometimes 

 lobed, sometimes elongated at the beaks ; hinge 

 mostly without teeth, marked by a furrow or by 

 a subulate line, which is crenated in some of the 

 species. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



Though all the Mytili are not inseparably at- 

 tached to other substances, they are by some means 

 rendered stationary ; the siljcy filaments produced 

 by some of the species are entwined in the cora- 

 lines and stones at the bottom of the sea, and 

 securely anchor the group of muscles found there. 

 Others of the species perforate rocks or even 

 large shells, and form for themselves at once 

 their residence and grave. The Mytili which 

 have their beaks nearly terminal and pointed, and 

 are of a dark colour, much resemble a mouse, 

 and from the circumstance of a few species being 

 like this animal, the genus has received its name, 

 which is derived from pmXo? (mutilos) the di- 

 * Plate X. figure 2. 



