20 LESSON III. 



carnivorous * mollusca have usually a kind of 

 proboscis ; this instrument is a fleshy pliable tube 

 terminated by a round aperture, with a cartilagi- 

 nous edge armed with little teeth. f The proboscis 

 is supplied with muscles, by means of which 

 the animal can protrude or draw it in at pleasure; 

 many use it to pierce other shells, that they may 

 suck out the flesh of the inhabitant. I have 

 mentioned to you three different kinds of mouths 

 which mollusks are found to possess ; describe 

 them to me. 



Child. Some have only a simple opening, 

 others have jaws, either of a horny substance, 

 or armed with teeth ; and others possess a plia- 

 ble fleshy proboscis, moved by muscles, and ter- 

 minated by a cartilaginous ring which has teeth. 



Teacher. Which are the feeders upon vege- 

 tables, and which upon animals,? 



Child. The mollusks which have a muzzle 

 feed upon vegetables, those with a proboscis are 

 carnivorous. 



Teacher. In feeding there is another point to 

 be considered, how the food is to be brought to 

 the mouth. How do we manage this operation ? 



Child. By means of our hands ? 



Teacher. And what makes it particularly 

 needful that man should possess hands ? 



Child. His erect position. 



Teacher. You have often had an opportunity 

 of watching some of the mollusks which are 



* From the Latin carne, flesh, and voro, I eat. 

 t Voluta tnusica. 



