PHOLAS. PIDDOCK. 143 



PHOLAS. PIDDOCK. 



Shell with two large primary valves, open at both 

 ends, and several lesser ones about the hinge : 

 teeth long, incurved, one in each valve on the in- 

 side. 



1. Pholas Dactylus. Prickly Piddock. 



L'ster t pi. 433. f. 276, and App. pi. 19. f. 1, 2 Pennant, 

 pi. 42. f. I Da Costa, pi. 16. f. 2 Donovan, pi. 118 

 t? r ood, pi. 13. f. 1, 2, 3 Dorset Cat. pi. 3. f. 2. 



Shell very thin, white or with a ferruginous tinge, ob- 

 long-oval, sometimes distorted, ribbed longitudinally, and 

 striate transversely in a fainter manner ; the ribs on the 

 larger end beset with numerous small concave spines, which 

 towards the smaller end become thin scales : at the larger 

 end is a vast oval gape in front, where the margins slope 

 into a curve on each side, the edges of which are generally 

 fringed with spines and reflected on the back ; the smaller 

 end elongated and gradually sloping into an obtuse rounded 

 point, where is also a large gape : hinge reflected on the 

 back, separated by transverse scaly partitions into from, 

 twelve to sixteen cells, which are covered with two oblong 

 very thin plates or rather membranes connected length- 

 ways, and supported by another triangular strong plate at 

 the bottom ; below the hinge is also another long narrow 

 thin plate attached to the sides of each valve by ft connect- 

 ing membrane, and reaching nearly to the smaller end : 

 teeth long, curved, flat and broad towards the top, where 

 they are rounded and ribbed : length sometimes two inches, 

 and" six in breadth. 



Burrowed in sandstone, wood, and clay. v.v. 



2. Pholas parva. Small Piddock. 



Montagu, pi. l.f. 7, S Pennant, pi. 43. f. 1. 



Shell oval, rough, white, striate transversely and longi^ 

 tudinally, except at the smaller end which is sometimes 

 covered with a rough brown wrinkled skin ; the larger end 

 sloping into a beak like the last, and forming a very wide 



gape 



