80 INTRODUCTION TO ZOOLOGY. 



The Eyes. 



1. Are the eyes movable? Are there eyelids? In 

 what direction can this fish see? What parts of the 

 eye can you see? 



2. Find the anteorbital bone in front of the eye, 

 and the suborbital below it. 



3. Insert your finger into the mouth and find out 

 whether there is a bone between the mouth and the 

 eyeball. 



The Nostrils. 



How many nostrils (nares) are there, and how are 

 they situated? Do they open into the mouth? Of 

 what use are they? 



The Mouth. 



1. See how the jaws open. Note the shape of the 

 mouth, when it is open and when it is closed. 



2. The bones in the upper lip are the premaxil- 

 laries. How many? 



3. Observe the backward extension of the premax- 

 illary on top of the snout. 



4. Do the premaxillaries bear teeth? 



5. Observe the bones just back of the premaxil- 

 laries. These are the maxillaries. Do they have 

 teeth? What is their shape? 



6. Find a small patch of teeth in the roof of the 

 mouth. These are borne on a bone called the vomer. 



7. Find two bones (palatine bones) along the sides 

 and a little way back of the vomer. Do they have 

 teeth ? % 



8. The front bone of the lower jaw is the dentary. 

 Does it have teeth? 



9. Examine the tongue. Can it be thrust out of 

 the mouth? Does it bear teeth? 



10. Can you find teeth anywhere else in the mouth? 



