192 



THE GENESIS OF SPECIES. 



[CHAP. 



In efts, as Prof. Gegenbaur himself has pointed out, 21 

 there is a striking correspondence between the bones or 

 cartilages supporting the arm, wrist, and fingers, and those 



A. SKELETON OF ANTERIOR EXTREMITY OF AN EFT. 



B. SKELETON OF POSTERIOR EXTREMITY OF THE SAME. 



sustaining the leg, ankle, and toes, with the exception 

 that the toes exceed the fingers in number by one. 



Yet these animals are far from being the root-forms from 



SKELETON OF A PLESIOSATTRTTS. 



which all the Vertebrata have diverged, as is evidenced from 

 the degree of specialization which their structure presents. 



21 In his work on the Carpus and Tarsus. 



