rambles, and a varied addition to our cabinet curiosi- 

 ties. The neighbourhood of Nottingham is very proliJic 

 in shells; all the sjiecies we find, however, are not 

 strictly British; some few of them have been acci- 

 dentally introduced from other countries, and arc now 

 naturalized and abundant; consequently we are com- 

 pelled to include them amongst our British species, 

 merely recording the fact that they were introduced 

 into this island. 



The shell, or covering which protects these animals, is 

 composed of carbonate of lime, which they obtain from 

 the alkaline earth in contact with the atmosphere. 

 With these facts before us we are necessarily obliged to 

 look upon each mollusc as a chemical composition, 

 drawn into action by chemico-electrical excitement, or, 

 in plain words, the vital action of the animal. 



It is to the remains of shells that we are indebted for 

 the basis of limestone mountains. From this valuable 

 branch of natural history we learn several wonderful 

 truths; on examining their fossil remains we find that 

 great disturbances have taken place on the earth's sur- 

 face since the creation of the world. Fossil marine 

 shells are procured from localities far beyond where 

 any ocean could have conveyed them under causes at 

 the present time existing: the summits of the Andes 

 and Pyrenees are not without them. Thus we discover 

 former inhabitants of the ocean deposited 14,000 feet 

 above the level of the tide. 



Land and fresh-water shells are divided into two 

 classes, namely, bivalves, or those which have two 

 similar shells united by a hinge at the summit, and 

 univalves, which are formed of one continuous whorl 

 or coil. Land shells are, without an exception, 

 univalves. 



The convolutions of shells are called whorls. The 

 hinge in bivalves, which unites the two halves together, 



