Fig. 35. 



British Gaper (Mya truncata). 

 a. foot : b. siphon-sheath ; c. exhalant siphon ; d. inhalant siphon ; e. um 



bones or beaks ; f. anterior, </. posterior end of shell 



Fig. 30. 



Fig 37. 



Shell of Pholas dactylus. 

 Side-view on the left showing rows 

 of sharp teeth towards front edge 

 above. Dorsal view on right showing 

 additional plates between the valves. 

 Reduced. 



Valves of Petricola pholadiformis 



(above), and Pholas Candida (below). 



