28 1HE MAMMALIA. 



the amphibian or reptile species. Now the fact 

 that direct descendants of reptiles, with a uniform 

 set of teeth, should acquire distinctive corner teeth 

 (canines) in consequence of their tearing their vic- 

 tims, as is the habit of beasts of prey, and that 

 certain mammals have acquired these teeth also, 

 owing to their having taken to flesh-eating, is a 

 convergence that can be most satisfactorily ex- 

 plained as the result of the same activity upon 

 similar or the same developments in the earlier 

 forms of teeth. It is, as we have already said, 

 a case of convergence of the most superficial kind. 

 Among living reptiles in the Hatteria, Uromastix 

 spinipes, and also a species of agama we meet 

 with advances towards the dentition of the Car- 

 nivora. But even when the canine is followed at 

 first by small pointed teeth, and then by broader 

 ones, there is nothing, either here or in the case of 

 the fossil African reptiles, that can be pointed out 

 as ' peculiar molars with broad crowns ' (Wieders- 

 heim). 



It is self-evident that given a like beginning 

 and like circumstances, we will more readily meet 

 with similar and the same phenomena than where 

 there was inequality to start with. In other 

 words homceogenetic convergencies occur most fre- 



