PREFACE TO THE SECOND EDITION. xiii 



that of plants or animals. This, however, is a 

 mistake; the well-defined, and varied forms of 

 shells, their beautiful colours and markings, 

 render them particularly attractive, and afford 

 better opportunities than any other branch of 

 natural history, for calling into action the per- 

 ceptive powers. They are well suited to succeed 

 " Lessons on Objects ; " the specimens may 

 be examined in the same manner, and their parts 

 and qualities described, and no other science 

 present the same facilities of bringing before 

 children, and exercising them in, the principles of 

 classification. An additional interest is given 

 to the study, when the accordance of the shell 

 with the habits of its animal can be traced. 



