CONCHIFERA OR BIVALVES. 113 



gular, ham-shaped ; bosses terminal, the other 

 extremity gaping ; no teeth ; a long and some- 



what internal ligament ; shell thin and fragile. 

 Animal, foot thin, worm-shaped. — 16 species 

 recent, and 4 fossil. 



The Pinna is usually found moored to the 

 sand by its byssus ; it is common to nearly all 

 seas, and grows to a considerable size, some 

 specimens being a foot and a half long ; one 

 species is found in our own seas on the coasts of 

 Dorsetshire and Sussex. Pearls are occasion- 

 ally found in the shell of the Pinna, but they 

 are of an amber colour and of little value; 

 sometimes a small species of crab takes up 

 its abode inside, without prejudice to either 

 party. A species found in the Mediterranean 

 is much sought after by the inhabitants of Si- 

 cily and Calabria, not only as an article of food, 

 but also for the sake of its byssus, w T hich is 

 I 



