Classification of Birds 



281 



FIG. 1 68. Because the breast of the young robin is speckled, it 

 is believed that the robin is descended from an ancestor that 

 had a spotted breast. 



birds, because young plants and animals are believed to 

 come through, in their development, the same changes 

 that the race has undergone (page 114). Young robins 

 and bluebirds have spotted breasts, as the thrushes 

 have throughout life. For this reason it is believed that 

 the ancestor of the thrush family had a spotted breast. 

 A careful study of the development of the young before 

 hatching is therefore made in order to determine the 

 relationships of birds. 



Scheme of classification. If a naturalist wished to 

 classify a ruby-crowned kinglet, he would at once place 

 it in the animal kingdom. He would also know that it 



