Branch Mollusca 83 



IV. — Study the locomotion of the living snail : how is it 

 effected ? Can the snail move in any direction in the 

 water or on a damp surface outside ? How does the 

 large foot on which it moves differ from that of the 

 clam ? Can you detect any motion of the different 

 parts of the foot while the snail is moving ? 



V. — Where are the tentacles? How many are there? 



Can you see a small spot at the base or the tip of the 

 tentacles ? These spots are the eyes. 



VI. — As the snail crawls up the wall of the aquarium or 

 along the surface film of the water, you can see the 

 mouth. Is it longitudinal or transverse as compared 

 with the direction of the body ? Describe its move- 

 ment in opening and closing. When it is open, can you 

 see a black object moving back and forth ? This is the 

 tongue. When magnified this tongue is seen to be 

 jagged in outline. 



VII. — Do snails in the water come to the surface occa- 

 sionally ? If they do, can you see a bubble of air escap- 

 ing from an opening in the mantle of each under the 

 lip of the shell? This is the opening to the curious 

 lung these snails have. 



VIII. — The eggs of snails may be frequently found on the 

 sides of the aquarium. They appear as small granules 

 imbedded in a gelatinous mass. Examine some of 

 them through a lens. 



IX. — Make a drawing of a side view of the snail and its 

 shell. 



THE SQUID 



The squid is a marine mollusc which is frequently 

 caught by fishermen in their nets. 



I. — Study the animal as a whole. What characters should 

 you say ally it to the class MoUupca ? Notice the long 



