178 VERTEBRATES 



the nictitating membrane, which serves the purpose of a 

 third eyelid. Can you find a nictitating membrane in your 

 eye? Find the ears. Of what do they consist? Are they 

 protected ? Open the mouth by pulling down the lower bill, 

 or mandible. Note the method of attachment to the head. 

 Is it attached directly or does it have another bone at the 

 point of union? Move it back and forth to test it. Is the 

 ui)per mandible movable ? Grasp the base of it with the fin- 

 gers and attempt to move it up and down. Look in the 

 mouth. Do you find a lower and an upper jaw as in the 

 frog? Do you find any indication of teeth either above or 

 below? Observe the tongue. Can it be extended like the 

 tongue of the frog? Do you find any indication of nerves 

 of taste? Give reason for your answer. 



(4) Study the covering of the body. Is there a covering 

 where the feathers have been removed ? What is it ? Study 

 one of the hairlike projections under the microscope. Draw 

 (X2). Scrape the skin gently with the scalpel, put a por- 

 tion of the material obtained under the low power of the 

 microscope. Compare it with the scales of the fish. Study 

 the various parts of the body. Is it covered entirely with 

 feathers? Locate carefully the feathered and unfeathered 

 areas. Is this feature an advantage to the bird ? Study the 

 covering of the legs and feet. How does it compare with the 

 covering under the feet? How do the parts of this covering 

 join on the sides? Draw several of these plates showing this 

 union (X4)- Study the nails and the bill. What is their 

 method of union with the body? Do they grow out of the 

 body? How do they compare in color, texture and hard- 

 ness with the scales on the toes and legs ? What seems to be 

 the special use of the nails? 



