76 



Shell Life 



varying from 10 to 15 inches in lengtli, with a 

 greatest breadth of more than half that measurement. 

 The shell is wedge-shaped, the beaks at the extreme 

 front, the broad end gaping and closure impossible. 

 For two-thirds of their upper margins the valves are 

 connected by a narrow, horny, elastic ligament, set 

 in a fold of the toothless hinge-plate. The glossy, 

 horn-coloured, thin shell is marked by lines radiating 



Fan Mussel 



from the beaks to the hinder margin, and lines of 

 growth crossing these. The animal, which varies in 

 colour from yellow to red-brown, uses its foot chiefly 

 for spinning the strong and abundant byssus by 

 which it moors itself to the bottom. The connection 

 between form and habit is at once seen in all the 

 members of this order : they are inactive creatures, so 

 the foot, which is primarily a locomotive organ, has 

 dwindled to small proportions. The byssus — shown 



