The common Whelk. Proboscis everted ; tentacles. 



GASTEROPODA 



Foot with operculum. 



6. Buccinum. 



Shell. 



7. Removed from shell, mantle-cavity opened. Rectum, anus ; ctenidium, one only, the left 

 (primitive right), persists. Mucous folds ; complicated osphradium. Renal opening at hind end of mantle- 

 chamber. In female, opening of oviduct. In male, long penis with convoluted vas deferens passing 

 along its left side and opening on a small papilla near its apex. 



67 



