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 strise in a radiated form from the um- 

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

 with short spines ; hinge smooth arid reflected, 

 teeth slender and curved ; one valve has a curved 

 lamina above the tooth ; there is a single acces- 

 sory 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 

 coasts ; the stone in which they are imbedded is 

 a mixture 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 phos- 

 phorescent solution, which would be of sufficient 

 power to decompose the rock by the contact of 

 its gradually increasing bulk. 



* Plate X. figure 8. 



