PHOLAS. 



31 



tool, the hole would be nearly circular, instead of 

 being accommodated to the shape of the shell, as 

 is seen to be the case. However they get into 

 the stone, there they may be everywhere found, 

 and it does not seem to be of much importance 

 whether their habitation be limestone, sandstone, 

 chalk, or oak. Even the Plymouth breakwater, 

 solid stone as it is, was very soon attacked by 

 these creatures. 



They are especially obnoxious to the builders 

 of wooden piers, for they seize on the submerged 

 portion of the piles on which the pier rests, and 

 do their utmost to reduce them to a honey- 

 combed state with the least possible delay. 

 Lately, however, the Pholades have been con- 

 quered; for they cannot pierce iron, and it is 

 found that if iron nails are closely driven into 

 the submerged portion of wooden piles, they 

 bid defiance to the Pholas. 



The specimen represented in our figure is 

 shown resting in its rocky bed, and seen edge- 

 ways. At each side may be seen the furrowed 

 shells ; the foot appears in the centre, surrounded 

 by the mantle, and the tube is seen projecting 

 far beyond the shell. Very many good specimens 

 may be obtained by splitting open the piece of 

 rock, and thus the shells extracted without injury 



