132 Mnascl Btil.s : tlielr PnnliwlivUtj and Maintenance 



Poiterior-, 



Antei'!"!'. 



Central (j 



Siphonal c^d 



BySSUt 



Fig. 3. Fixation of Mussels; Growth Marks, dsc. 



a. Mode of anchorage in a muddy or sandy substratum exposed to currents, b, c. Mode 

 of fixation to vertical surfaces, — solitary and crowded conditions, d. Mu'-sel, with ridges 

 on shell denoting its age. The thick numbered lines are " wmter marks," — theiefore, 

 the individual figured is five winters old. It is a "seed" mussel, from the Ro-ddu 

 "Wear," Aberdovey. The right side (valve) is shown. 



