THE PIGEON 177 



Make drawing of tadpole in various stages of develop- 

 ment. 



Summary. — What are the principal changes in environ- 

 ment as the frog goes from the water life to the land life? 

 What are the changes of structure undergone to meet these 

 conditions? What are the advantages of the change to the 

 frog ? What are the disadvantages ? What does this change 

 suggest as to the past history of the frog? 



THE PIGEON 



Ectopistes migratorius 



External Morphology. — (i) The pigeon should be 

 killed with chloroform and the feathers removed from nearly 

 all of the body. Lay the specimen down with the head from 

 you and the ventral side up. Note the extension of the 

 vertebral column anteriorly forming the neck, and the short, 

 blunt extension of the vertebral column into the tail. 



(2) Observe the shape, form and place of attachment 

 of the wings and legs. Move them to ascertain the range 

 of motion of each. How many principal segments in each? 

 Are the limbs especially modified? Explain. How many 

 toes? How located? Study the toes and their freedom of 

 motion. Are the feet webbed? What is the nature of the 

 pads? Of what use are they ? 



(3) Observe the size and shape of the head and its at- 

 tachment to the neck. Turn it in various directions to test 

 its range of motion. Observe the nostrils. How many? 

 Where located? Do you find eyelids? How does a bird 

 wink its eye? Find on the inside lower corner a membrane, 



STU. IN ZOOL. — 12 



