Plate XI 



^j- 



^"X::. 



41 



Organisms injurious to Thais lamellosa. 

 Upper row:- Barnacles encrusting the shells. 

 Middle row:- Tubes of serpulid worms. Thais 

 drilled by a naticoid snail. 



Bottom row:- Perforations by burrowing worms. 

 Injury caused by boring sponges. 



