VIIL] 



HOMOLOGIES. 



19^ 



the particular view advocated by tlie learned Professor is 

 open to criticism. Thus, it may be objected against his 

 view, first, that it takes no account of the radial ossicle 

 which becomes so enormous in the mole ; secondly, that it 

 does not explain the extra series of ossicles which are 

 formed on the outer (radial or marginal) side of the paddle 

 in the Ichthyosaurus ; and thirdly, and most importantly, 

 that even if this had been the way in which the limbs had 

 been differentiated, it would not be at all inconsistent with 

 the j)c>ssession of an innate power of producing, and an 



SKELETON OF AN ICHTHYOSAUKUS. 



innate tendency to produce, similar and symmetrical homo- 

 logical resemblances. It would not be so because resem- 

 blances of the kind are found to exist, which, on the 

 Darwinian theory, must be subsequent and secondary, not 

 primitive and ancestral. Thus we find in animals of the 

 eft kind (certain amphibians), in which the tarsus is carti- 

 laginous, that the carpus is cartilaginous likewise. And 

 we shall see in cases of disease and of malformation wliat 

 a tendency there is to a similar affection of homologous 

 parts. In efts, as Professor Gegenl)aur himself has pointed 

 out,^ there is a striking correspondence between the 

 bones or cartilages supporting the arm, wrist, and fingers, 



1 In his -work on tlie Carpus and Tarsus. 



