Mammalia. 143 



6. Make a drawing of one half of the kidney as seen from the 

 inside, showing all the above-named points. 



7. Cut across the middle of the kidney at right angles to its 

 length, and make a drawing of this cross section. The projec- 

 tion of the kidney substance into the cavity opposite the ureter 

 is the urinary pyramid, and from its apex, from many fine holes ? 

 issues the urine which the kidney has secreted from the blood. 



DISSECTION OF THE HEAD OF A RABBIT. 



1. Remove the skin from the head. Observe the cartilages of 

 the ears and cut them off close to the head. 



2. Below and back of the ear is an irregular pinkish mass, the 

 parotid salivary gland. The duct which conveys the saliva runs 

 forward over the cheek and opens on the inside of it. The 

 duct is usually hard to see, as it is thin-walled, slender, and of 

 about the same color as the sheaths of the muscles on which it 

 lies. It may easily be mistaken for a nerve, several of which 

 should now be in sight. This duct is much more readily traced 

 in a dog. With sharp, fine pointed scissors cut into the edge of 

 the duct, insert a black bristle, and push toward the front. 



3. Just back of the angle of the lower jaw find a roundish 

 body, the submaxillary salivary gland. Its duct runs forward 

 inside the lower jaw and opens under the front part of the 

 tongue. It is rather difficult to trace in the rabbit, but is much 

 easier in the dog. 



4. The infraorbital gland is just below the front of the eye 

 and its duct opens near that of the parotid gland. 



5. The sublingual gland is a small, slender gland close to the 

 inside of the lower jaw in front of the base of the tongue, and its 

 duct opens near that of the submaxillary. 



6. Observe the muscle that covers the outside of the back 

 part of each lower jaw. This is the masseter muscle. Place the 

 fingers on the angles of your own jaw and note the action of 

 the masseter muscles in shutting the teeth firmly together. 

 In the rabbit note the attachment of the masseter muscle to the 



