M0LLU8KS. 407 



and large stone at the seorside. The variety of its attachment to 

 the rocks is very curious, and well repays a careful .examination. 

 Every one who has seen a living limpet knows how firmly it fixes 

 itself to the rock. This is done by the inhabitant creating a 

 vacuum on the under surface of its body, which causes the pres- 

 sure of the atmosphere to keep it so tightly fixed to the rockS; 

 that a blade of a strong knife is required to detach it. Frequently 

 the margin of the shell adapts itself to the shape of the substance 

 to which it adheres, proving that it must remain fixed in the same 

 spot for a long time, and rendering it difficult to imagine from 

 whence it can obtain sufficient nourishment to support life. 



Sometimes a large shell may be picked up covered with 

 limpets, that adhere firmly to it in spite of the rolling of the 

 waves, and the tossings about to which it must necessarily be 

 subjected. 



The Bivalves do not enjoy such powers of locomotion as 

 the Univalves, yet some, as the fresh-water mussel, can urge them- 

 selves along by means of a fleshy organ called the foot; and so 

 powerful in some is this organ, that by means of it the animal can 

 not only burrow in the sand, but actually leap out of a boat. The 

 rapid opening and shutting of the valves is used by some, as the 

 scallop, as a means of progression. It is believed that the Bivalves 

 have no visual organs. 



The Scallop is peculiar to the seas of Europe. It is a 

 singular fact, that in the stomach of the common Scallop is found 

 an earthy deposit, which, when boiled in nitric acid in order to 

 dissolve the animal and other portions, exhibits under a powerful 

 microscope animalcules precisely similar to those which, in a fossil 

 state, form the earth on which the town of Eichmond in America 

 is built. 



The Common Oyster has been for many ages considered 

 as a delicacy for the table. In the times of the ancient Romans, 

 we find that Oysters were exported to Eome from the coasts of 

 Britain, and there placed in the Lucrine Lake, where they were 

 fattened. 



On our coasts the oysters breed in large beds. During the 



