2-JO 



MANUAL OF ZOOLOGY 



visceral mass (Fig. 161, v. m), which passes below and in 

 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 



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

 from the epithelium (Fig. 160, ep.i) covering these parts 

 that the shell is formed as a cuticular secretion. The whole 



