108 ANIMALIA MOLLUSCA. 



FAMILY III. INCLUSA. 



Mantle opening at the anterior end, or towards the middle, 

 only for the passage of the foot, and prolonged at the other 

 end into a double tube, which issues from the shell. 



GENUS TEREDO. 



Mantle prolonged into a tunnel much longer than the two 

 little rhomboidal valves, and terminated by two short tubes, 

 the base of which is furnished on each side with a stony and 

 movable pallette. The Teredo penetrates while young into 

 the wood which it finds submerged, where, by the aid of its 

 valves, it digs out for itself a residence, enlarging it as it 

 grows in size. 



