n. 55. / 147. 



Boring Molluscs and Sponge. <i. 

 Top: Left, Saxicava rvgosa ; centre. Oyster bored by Sponge, Clione. 

 Right, the Piddock (I'holas dactylus . 



Bottom : Red Sandstone bored by various kinds of Piddock, 



(pp. 147. 14S. 149). 



