6:i 



CONCHIFEEA. 



the tips, wliicli are fringed, but not disked ; foot 

 large, short, truncate. Bores into various sub- 

 stances. 



P, dactylus. 



j)arva. Fig. 63 ; ?i. s. 



crisj)ata. 



Candida. 



61 



63 



62 



64 



Pholadidea (Leach). Nearly as PJwIas, but the 

 shell has no callosities, and tliere is a cup-like 

 appendage surrounding the base of the siphons ; 

 the siphons terminate in a fringed disk. 



P. papyracea. Fig. 62 -, n. s. 



Family II. Gastroch^nad^. 



Shell equal-valved, very unequal-sided, gaping 

 in front ; pallial line sinuated. Animal oblong or 

 club-shaped ; siphons capable of being greatly 

 lengthened, wholly united ; mantle closed, except 

 to give exit in front to a minute foot. Bores into 

 stone. 



