45 



PHOLAS. 



(See Plate III. fig. 4.) 



Shell bivalve, inaequilateral, divaricate or gaping, 

 beaked ; having smaller accessory valves situated 

 upon the hinge and posterior slope. Hinge re- 

 curved, furnished with a tooth. 



The Pholades, as their name, derived from the 

 Greek (ficoAsw, imports, seek a hiding-place in all 

 descriptions of rocky fragments, and even in wood, 

 piercing the substance while they are young, and 

 gradually increasing the dimensions of their cell 

 according to their growth. The largest species 

 and the finest specimens are most frequently found 

 in chalk, which being the softest of calcareous 

 rocks, admits, perhaps, of a more easy and rapid 

 progress, than the indurated stones in which thev 

 are sometimes discovered. It is not, however, yet 

 understood by what instrument they are enabled 

 to penetrate the substance of their future prison ; 

 when, judging from the size of the aperture, they 

 are still in a young and, probably, a feeble state. 



