134 PRACTICAL ZOOLOGY. 



2. Note the branches of the facial nerve running up- 

 ward over the cheek. Dissect away the parotid gland, 

 and find where the facial nerve emerges from the skull. 



3. In the angle between the two branches of the lower 

 jaw observe two roundish bodies, the submaxillary 

 salivary glands. In the dog trace their ducts as in 

 the case of the parotid. 



4. Observe the muscle which covers the outside of the 

 back part of each lower jaw. This is the masseter 

 muscle. Place the fingers on the angle of your own 

 jaw and note the action of the masseter muscle in 

 shutting the teeth firmly together. In the rabbit 

 note the attachment of the masseter to the under edge 

 of the cheekbone. Trim the muscle entirely away. 



5. After removing the submaxillary glands, a muscle 

 will be found on each side having its origin on the 

 inside of each half-jaw near their junction. These 

 are the digastric muscles; they depress the lower 

 jaw. Cut away all the muscles and other connec- 

 tions and remove the whole of the lower jaw. 



6. Carefully examine the tongue. 



7. Thoroughly clean the lower jaw and examine the 

 teeth. How is the lower jaw hinged to the skull, and 

 what motion does this hinge allow? How does the 

 rabbit move its lower jaw? What is the relation 

 between this jaw-motion and the direction of the 

 ridges on the grinding teeth, or molars? 



8. Observe the opening on the inner surface of each 

 half-jaw where the nerve entered to supply the teeth. 



9. Look at the side of the back part of the mouth for an 

 opening leading toward the ear, the Eustachian tube. 



10. Trace the nasal passages. 



