THE EVOLUTION THEORY 



111 



When we observe some of the living forms of reptiles and birds 

 they appear so widely differentiated that no one would suspect 

 them of being closely related. In Archaeopteryx, however, we 

 have an animal which is neither bird nor reptile, but a transition 

 form, uniting in its body the characteristics of both classes. It 

 was probably as large as a rook. The plumage, which covers the 

 whole body and develops in the wings into long flying-feathers, 

 the merry-thought (furculum\ and the structure of the bones 



FIG. 28. PEEIPATUS CAPENSIS. 



prove beyond doubt that the Archaeopteryx belongs to the birds. 

 On the other hand, the shape of the vertebrae, the presence of 

 teeth, the three-fingered reptile-hand armed with claws, the long 

 lizard-like tail containing twenty vertebrae unmistakably indicate 

 that it is closely related to the reptiles. 



Such transition forms exist among the living animals. The 

 Peripatus, a little animal measuring about 10 cm. and living 

 in South Africa and New Zealand, resembles in appearance a 

 myriapod (fig. 28). Its discovery gave rise to fierce contro- 

 versies, for the Peripatus unites in its body a remarkable mixture 



