202 

 PHOLAS Candida* 



WHITE STONE PIERCER. 



Specific Character. Shell oval, obtuse, nearly 

 closed at the anterior end, thin, fragile, almost 

 transparent, striated transversely, and crossed 

 by finer striae in a radiated form from the um- 

 bones, a few of the radii at the larger end set 

 with short spines ; hinge smooth and reflected, 

 teeth slender and curved ; one valve has a 

 curved lamina above the tooth ; there is a single 

 accessory valve ; the colour is yellowish white ; 

 it is about three quarters of an inch long, and 

 three inches broad. 



These Pholades inhabit marine rocks ; they 

 are found in great numbers on the Devonshire 

 coast ; the stone in which they are imbedded is 

 a cementation of the finest sand and limestone ; 

 it is very soft when first taken from the bed, 

 and so absorbent as to afford sufficient moisture 

 for the purposes of life, and for the peculiar 

 actions of the mollusk. The animal secretes a 

 mild phosphorescent solution, which would be 

 of sufficient power to decompose the rock by 

 the contact of its gradually increasing bulk. 



* Plate X. figure 8. 



