MOLLUSCA. 19 



LESSON III. 



Teacher. What organs in the mollusca have 

 we considered ? 



Child. The organs of sense and of motion. 



Teacher, And what other organs are essential 

 to animal existence ? 



Child. All animals must have organs by 

 which they feed themselves. 



Teacher. Have you ever observed snails 

 eating ? 



Child. Yes ; I have seen them devour a leaf, 

 and I should think they must have teeth. 



Teacher. They have two jaws which are fur- 

 nished with small teeth, fitted for cutting vege- 

 table substances. 



Child. Have all the mollusca mouths like 

 that of the snail ? 



Teacher. No, the mouths of the different 

 species, as well as their other organs, are adapted 

 to the peculiar wants and habits of the animals. 

 Some have only a simple opening to receive the 

 little animalcula brought to them by the waves, 

 and which do not require mastication.* Most of 

 those which live upon the produce of the vege- 

 table kingdom have a muzzle with jaws which 

 are either horny or armed with teeth, f The 



* The Oyster. t The snail. 



C 2 



