SHELLS. 41 



LESSON VI. 



Teacher. To-day you shall tell me all that 

 you remember respecting shells. I will put it 

 together in a more regular manner, and you shall 

 learn by heart the written account. 

 Shells. 



Shells are the coverings or habitations of a 

 species of mollusca. They are formed by the 

 animal himself of carbonate of lime and gela- 

 tine : these substances are secreted in glands in 

 his body. The colouring matter exudes from the 

 pores of the mantle ; it penetrates the shell be- 

 fore it is hardened, and the colours being ar- 

 ranged in order in the mantle, give the shell the 

 peculiar markings which belong to the different 

 species. When any accident happens to the 

 shell, the animal is enabled to repair it in the 

 same manner that he at first made it. The size 

 of the shell is in proportion to that of its inhabit- 

 ant ; small at first, but continually increasing 

 till the animal has attained his full size. 



Teacher. Before we enter more fully upon 

 the study of shells, and their classification, I 

 wish to direct your attention to two circum- 

 stances very conspicuous in the works of the 

 Creator. The first is, the economy displayed 

 by God ;* you seem surprised. 



Child. Yes, it is so very extraordinary to talk 



* Paley's Natural Theology. 



4* 



