8 LESSON I. 



Teacher. The tentacula vary in number; many 

 mollusks have only two. The sense of feeling 

 resides always in nerves. 



Child. Then the mollusks must have nerves. 



Teacher. Yes, they have nerves. Do you 

 perceive any other organs of the senses besides 

 the tentacula ? 



Child. There are black specks on the horns 

 of the snail which appear like eyes. 



Teacher. These specks are the organs of sight, 

 of which mollusks have never more than one pair. 

 The sense of seeing, is not universally possessed 

 by this class of animals. The organs of hearing 

 and smelling have never been discovered in any 

 of them, but they are supposed to possess the 

 latter from the readiness with which they select 

 suitable food. This circumstance also proves 

 that they possess the sense of taste. You must 

 now recapitulate all that has been said concerning 

 the mollusca. Whence is the name derived ? 



Child. From mollis, the Latin for soft. 



Teacher. What kind of body have they ? 



Child. Cold, slimy, soft, and fleshy. 



Teacher. Yes ; and another quality you ob- 

 served when I touched the snail several times. 



Child. That its body is contractile. 



Teacher. An<J what enabled it so quickly to 

 contract its body, and retreat into its shelter ? 



Child. Its being furnished with muscles. 



Teacher. When you compare these animals with 

 others, in what respect do they appear deficient ? 



