Hi LECTURES ON EVOLUTION 91 



distinctions are obvious and striking if you com- 

 pare the definitions of these great groups as they 

 now exist. 



The same may be said of many of the sub- 

 ordinate groups, or orders, into which these great 

 classes are divided. At the present time, for 

 example, there are numerous forms of non-rumin- 

 ant pachyderms, or what we may call broadly, 

 the pig tribe, and many varieties of ruminants. 

 These latter have their definite characteristics, 

 and the former have their distinguishing peculi- 

 arities. But there is nothing that fills up the gap 

 between the ruminants and the pig tribe. The 

 two are distinct. Such also is the case in respect 

 of the minor groups of the class of reptiles. The 

 existing fauna shows us crocodiles, lizards, snakes, 

 and tortoises ; but no connecting link between the 

 crocodile and lizard, nor between the lizard and 

 snake, nor between the snake and the crocodile, 

 nor between any two of these groups. They are 

 separated by absolute breaks. If, then, it could 

 be shown that this state of things had always 

 existed, the fact would be fatal to the doctrine of 

 evolution. If the intermediate gradations, which 

 the doctrine of evolution requires to have existed 

 between these groups, are not to be found any- 

 where in the records of the past history of the 

 globe, their absence is a strong and weighty 

 negative argument against evolution ; while, on 

 the other hand, if such intermediate forms are to 



