CONCHIPEEA. 



263 



FIG. 199. PINNA. 



The true Mussels (Mytilus) are well known to every- 

 body ; they frequent mud banks which are uncovered 

 at low water, are very prolific, and attain their full 

 growth in a single year. By means of a strong byssus 

 they fasten themselves to the rocks, where they defy 

 the violence of the storm. " The mussel is the owl 

 of the sea," says Charles Lamb ; " Minerva's fish, the 

 fish of wisdom. He hears the tide roll backwards 

 and forwards over him twice a day, as the Salisbury 

 coach goes and returns in eight-and-forty hours ; but 

 he knows better than to take an outside place on it." 



The Eiver Mussels ( Unio) are met with in fresh- 

 water lakes, rivers, and ponds throughout the whole 

 world. In some of them pearls are found which are 

 bright and of exquisite lustre ; formerly, there were 

 extensive fisheries of them both in Wales and Scot- 

 land. One taken from the river Conway, in North 

 Wales, is to this day honoured with a place in the 

 royal crown of England. 



The third family of Conehifera embraces 



The Clams (Chamacea), in which the two sides of 



