EDIBLE BRITISH MOLLUSCA. 



PIDDOCKS, GAPERS, RAZOK-FISHES, ETC. 



Fam. PHOLADIELE. 

 PHOLAS.— PIDBOGK. 



Pholas Dactylus, Linnaeus. Piddock or Clam. — 

 Shell equi valve, oblong-ovate, gaping chiefly anteriorly, 

 inequilateral, thick, white exteriorly and inside polished ; 

 exterior covered with longitudinal furrows and con- 

 centric striae, with sharp radiating spines; no hinge; 

 beaks hidden with callosities ; a flattened spoon-shaped 

 tooth, which curves forward, in each valve; accessory 

 valves four in number. 



The perforating powers of the Pholas have for a 

 length of time been a subject of discussion amongst 

 naturalists, and appear likely to continue so. Some 

 thought that by means of its foot it perforated the soft 

 clay or stone which hardened round it ; and a Dutch 

 philosopher named Sellius, nearly 130 years ago, pub- 

 lished an account of the Teredo, wherein he showed 

 that its shell could not be the instrument of perforation, 

 and asked how it was possible that the extremely 

 tender shell of the young Teredo could make a hole in 



B 



