1 68 A GUIDE FOR THE STUDY OF ANIMALS 



Homology of the Vertebrate Skeleton 

 Materials. 



Prepared skeletons of an amphibian, a reptile, a bird, 

 another mammal, and man. If any of these be lacking, 

 lantern-slide illustrations may be used in a partially dark- 

 ened room. 



Observations. 



Having studied the frog's skeleton in detail, the student 

 can readily compare each of these types with it. Compare 

 in a very general way the skulls, the girdles, and the limbs ; 

 their form and use. Note variations in the form and num- 

 ber of the vertebrae and the number of the ribs. 



Questions. 



1. In which types of vertebrates are the joints between 

 the skull bones bound with cartilage ."" How does the 

 joining change in later types ? 



2. What dissimilarities occur in the series as regards 

 closure or boxing in of the eye orbits, nostrils, and skull 

 bones .■" How would these changes in joining and closure 

 affect strength, rigidity, and protection .'' 



3. What evidence is there that such improvement has 

 affected brain capacity and intelligence .' 



4. State how the attachment of the skull to the verte- 

 bral column changes as the animal man assumes an erect 

 position. 



5. Are the vertebrae of these types alike in structure ? 

 What is the general form of an horizontally placed verte- 

 bra, as in the horse or a reptile, and of a vertically placed 

 one, as in man .? If you see any differences, account for 

 them. 



6. Wherever possible, find the vertebrae of the neck 

 (cervical), and note the number of them in each case. 



