MOLLUSCA. 11 



LESSON II. 



(To commence with a repetition of the summary of the former 

 lesson.) 



Teacher. Examine these animals again, com- 

 pare them with insects, and tell me if you ob- 

 serve any deficiency in their construction. 



Child. They have not any limhs. 



Teacher. Very true. They have not limbs 

 and joints, as insects, nor are they divided, or 

 moved by means of rings, as worms. 



Child. Yet they move about. 



Teacher. Yes ; the greater number of mol- 

 lusks have the power of locomotion, that is, of 

 moving from place to place ; the term is derived 

 from the Latin locus, a place. We will first ex- 

 amine the organs by means of which this power 

 is exercised. In what manner do snails and 

 slugs make their way along the ground ? 



but the result will be most satisfactory both to the teacher and 

 pupils. The latter should acquire so clear a knowledge of the 

 facts brought before them, and have them so well im- 

 printed on their minds, that they may, through all their 

 progress, be enabled without confusion or hesitation, to recur 

 to each preceding step. Their information should be like a 

 chain, which is held unbroken in the grasp ; and when this is 

 accomplished, a power of mind is elicited which, independently 

 of the knowledge obtained, will prove most valuable when 

 applied to more important subjects. 



