Via. 30 



liritish ' Fan-Mussel ' (Pinna pectinata) : a. the|byssus : Case 157. 



Fig. 31. 



Common Edible Oyster (Ostrea edvlis). 



a. labial palpi ; b. gills ; c. mantle ; d. junction of the two folds of the mantle 



c. large adductor muscle : /. the shell. 



