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 

 attached to other subtances, all are by some 

 means rendered stationary ; the silky filaments 

 produced by some of the species are entwined 

 in the coralines 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 them- 

 selves 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 



* Plate X. figure 2. 



