XI 



PHYLUM MOLLUSCA 



269 



front into the foot (ft.). Thus each valve of the shell is in 

 contact with the dorso-lateral region of the body of its own 



i 



side, together with the corresponding mantle-lobe, and it is 

 from the epithelium (Fig. 148, ep. 1) covering these parts 

 that the shell is formed as a cuticular secretion. The 



