332 NATURALIST'S CABINET. 



Extraordinary powers of penetration. 



in external appearance, has a distant resemblance 

 to a muscle. It is found in the greatest quantity 

 at Ancona in Italy ; also along the shores of 

 Normandy and Poitou in France, and upon 

 some of the coasts of Scotland. It is highly 

 admired by the luxurious, who esteem it a great 

 delicacy. 



The great powers of penetration of these ani- 

 mals, compared with their apparent imbecility, 

 have justly excited the astonishment of philoso- 

 phers and naturalists in all ages. When divested 

 of their shell they are roundish and soft, with 

 no instrument that seems in the least fitted for 

 boring into stones, which they are known to do, 

 or even for penetrating the softest substance. 

 They are, indeed, each furnished with two teeth, 

 but these are placed in such a situation as to be 

 incapable of touching the hollow surface of their 

 stony dwellings. They have also two corners to 

 their shells that open and shut at either end; but 

 these are totally unserviceable to them as miners. 

 The instrument with which they perform all their 

 operations, and by means of which they bury 

 themselves in the hardest rocks, is only a broad 

 fleshy substance, somewhat resembling a tongue, 

 that is seen issuing from, the bottom of the shell. 

 With this soft yielding instrument, while yet 

 young and small, they work their way into the 

 substance of the stone, and tlv^y enlarge their 

 apartment as their increasing size renders it ex- 

 pedient. 



