PLATE I.XIX. 



is a diftinc"l species or only a young shell of that kind. As both 

 authors have however figured and described it separately, we have 

 given it a place as a distinct, or at leaft doubtful species. 



Pennant says he found these shells in masses of fossil wood in 

 the shores of Abergehi in Denbighshire: the bottom of their cells 

 were round and appeared as if nicely turned with some instrument. 

 According to this author they will also perforate the hardest oak plank 

 that is accidentally lodged in the water. Da Costa says they are 

 found in great quantities on the same c oasts as the other kind (Pholas 

 crispatus) nitched in the rocks and stones, and adds that there is an 

 amazing abundance at Scarborough and Whitby in Yorkshire, nitched 

 i i the Alum and other stones. 



