﻿FIRST BOOK OF ZOOLOGY. 



CHAPTEK I. 



FRESH-WATER SHELLS. 



For these lessons, it has been deemed best to commence 

 with the shells of mollusks, such as snail-shells and mussels. 

 They are better objects to examine than insects, being more 

 simple in structure, and less liable to be broken in handling. 

 When found alive, their habits can be readily studied, as 

 they can easily be kept alive in jars filled with water. 



1. Let the pupils first make a collection along the shores 

 of some lake or river, picking up all the different kinds of 

 shells they meet with. The waves will have thrown them 

 up on the shores, or in times of drought the waters will 

 have left them exposed. Certain kinds are very small, 

 though they will be found by sharp looking. Most of 

 the shells collected will be empty, and these shells are 

 called dead shells, because the soft-bocliecl creatures once 

 contained in them have died and decayed, leaving the hard, 

 limy shells. Some of the shells collected may contain the 

 animal, and at one time each of them possessed a little creat- 

 ure withim which was the fabricator of the shell. 



