THE BACKGROUND OF DARWINISM—ADAPTATIONS 193 
Fic. 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.) 
