78 STUDIES OP ANIMAL LIFE. 



h. How great a " range of vision " has the fish ? 

 (Refer to crayfish study, K 5 6.) 



c. Show by means of a sketch the iris and the pupil. 



d. How many eyelids are there ? 



e. Can a fish close its eyes? 



/. Does the fish notice things ? 



g. What means of protection have the eyes ? (Look 



at skeleton of a fish.) 

 h. What is the meaning of the unusual flattened 

 condition of the eye? 

 5. The Ears. The ears are small sacs embedded in the 

 skull. Each sac is lined with sensory hairs and 

 contains a small stone (otolith). This is " anatomi- 

 cal evidence " that a fish can hear. Can you give 

 any other evidence that the fish actually does 

 hear ? 



D. The Mouth. 



1. Observe how wide the mouth can be opened. 



2. Observe that the bones of the upper jaw are movable, 



allowing it to act as a " lip. " Show by sketches 

 the relation of these bones to each other. 



3. Has the fish teeth ? 



4. How does the fish seize its food ? 



5. Does the fish chew its food ? 



6. The Tongue. 



a. What is the shape of the tongue ? 

 i. Can the fish taste ? (Place bits of brown paper 

 and bits of fish food in the jar with the fish.) 



E. Bespiration, 



1. Identify the operculum, a flap with a bony framework 

 on each side of head. It covers and protects the 

 gills. 



