7l6 THE ORIGIN OF SPECIES 



the theory of evolution was established. As evidence for that 

 theory, it is really an extension of that from comparative anatomy. 



Pig, 550. — Bones of the hind leg and foot of primates (not to the same scale).— 

 From Young, The Life of Vertebrates, 1950. Clarendon Press, Oxford. 



a.,Tibiale ; c, unciform ; ca., fibulare ; cun., mesocuneiform ;/., femur ;/!., fibula ; gt., greater trochanter 

 h., head ; m., first metatarsal ; n., navicular ; p., proximal phalanx ; pa., patella ; t., tibia. 



As we have seen above (p. 673) early stages of chick and rabbit 

 are almost indistinguishable ; this means that their structural 

 plan is then the same, although as they grow they become 



