18 LESSON II. 



enveloped in this, as only to present an opening 

 where the mouth is situated, sometimes it spreads 

 over the shell, and sometimes it has external ex- 

 pansions answering the purpose of fins. The 

 mollusca have not warm red blood, but a white 

 cold fluid issues from their hearts and circulates 

 through their frames. They have nerves, and 

 consequently, feeling; and this sense seems 

 most acute in their tentacula. Some have eyes, 

 but others do not enjoy the sense of sight. They 

 appear to have the power of smelling and tast- 

 ing, but no traces of ears have been discovered.* 



LESSON II. 



To commence with a repetition of the summary of 

 the former lesson.) 



Teacher. Examine these animals again, 

 compare them with insects, and tell me if you 

 observe any deficiency in their construction. 



* This little summary of the substance of the lesson may be read 

 over twice to the children, and they should then be required to 

 write it as well as they can from recollection. It would be well also 

 that they should repeat it at the commencement of the succeeding 

 lesson. This process may appear tedious, 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 imprinted 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 j and were such the 

 case, a power of mind would be elicited which, independently of 

 the value of the knowledge obtained, woind prove its worth when 

 applied to more important subjects. 



