THE BACKGROUND OF DARWINISM— ADAPTATIOXS i 



93 



Fig. 40. — Three aquatic types of vertebrate, to illustrate convergent adapta- 

 tion of three wholly unrelated forms of marine life. All three show the fusiform 

 body, median and paired fins, though the skeletal structures are radically differ- 

 ent. A, shark (Pisces); B, ichthyosaur (Reptilia); C, porpoise (Mammalia). 

 {From Newman^ after Osborn.) 



