124 PHOLADIDiE. 



Family PHOLADID^. 



Shell gaping at both ends ; thin, white, brittle, and exceed- 

 ingly hard ; armed in front with rasp-like imbrications ; without 

 hinge or ligament, but often strengthened externally by accessory 

 valves ; hinge-plate reflected over the umbones, and a long curved 

 muscular process beneath each ; anterior muscular impression 

 on the hinge-plate ; pallial sinus very deep. 



Animal club-shaped ; foot short and truncated ; mantle closed 

 in front, except the pedal orifice ; siphons large, elongated, 

 united nearly to their ends ; orifices fringed ; gills narrow, pro- 

 longed into the exhalent siphon, attached throughout, closing 

 the branchial chamber ; palpi long. 



The cartilage of the hinge in these shells is small and internal ; 

 the ligament is strong and elastic, situated externally, and both 

 are further strengthened by an accessory membrane formed by 

 the coriaceous end of the mantle, which issues between the 

 anterior ends of the valves and covers the ligament ; this exten- 

 sion of the mantle is fixed by filaments which enter the dorsal 

 cells and is furnished usually with calcareous plates which main- 

 tain the valves in position. 



The Pholadidse perforate rocks, wood or clay ; the burrows 

 are vertical, quite symmetrical, and seldom in contact. 



Subfamily PEOLADIN^. 



"Valves with an anterior gap which is never closed in the adult 

 shells. 



Pholas, Linn., 1151. 



EtyTTi. — Pholas^ a burrowing shell-fish, from pholeo, to bore. 

 Piddock. 



Syn. — Hypogsea and Hypogaeoderma, Poll. 



Distr. — P. costata, Linn, (civ, 55-51). U. S. Fossil ; Jur- 

 assic, Cretaceous, Tertiary. 



Shell elongated, cylindrical; dorsal margin protected by two 

 accessory valves ; anterior and posterior in position ; umbonal 

 processes reflexed over the beaks, closely applied. Pallial 

 sinus reaching the centre of the shell. 



Animal with a large truncated foot, filling the pedal opening ; 

 body with a fin-like termination ; combined siphons large, cylin- 

 drical, with fringed orifices. P. costata is sold in the market of 

 Havana, where it is an article of food. 



Mr. W. Woods remarks that on the coast of Normandy the 

 Pholads are eaten in abundance, well seasoned and cooked with 

 fine bread'Crumbs and herbs. They are also reckoned a delicacy 

 when pickled in vinegar. In the neighborhood of Dieppe a 

 great many women and children, each provided with an iron 



