144 POPULAR CONCHOLOGY. 



differing in colour from the rest of the shell. 

 Animal, head very distinct, supporting two ten- 



tacula, having eyes at the lower extremity; 

 foot large, and round or oval. — There are 57 

 species recent. 



The genus Patella is to be found in all parts 

 of the world, chiefly on rocky coasts, and often 

 where the sea breaks with considerable violence ; 

 many species, (from the shape of the shell cor- 

 responding exactly with that of the rock on 

 which they have lived,) appear never to move 

 from the spot they have once selected, and even 

 form in most cases cavities in the rock itself 

 by a power they possess of absorbing its sub- 

 stance : the Patella vulgata of the British coast 

 has this property. 



The Patella cochlea is found at the Cape of 

 Good Hope ; it lives almost exclusively at- 

 tached to a larger species of the same genus, 



