270 



MANUAL OF ZOOLOGY 



SECT. 



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

 front into the foot (//). 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. 160, ep.i} covering these parts 

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



