GASTEROPODA 



3. Haliotis. Dorsal view of shell. Spiral ; row of pores. 



4. Shell removed and mantle-cavity opened. The two ctenidia with anus between them. Mucous 

 folds in mantle-roof. 



5. Patella. The common Limpet. Ventral view. Shell ; pallial branchiae forming a ring round 

 the foot in the mantle-groove. Head 



, 



