176 THE STORY OF REPTILE LIFE. 



known collectively as the Anomodontia, or, 

 according to some, as the Theriodontia, in refer- 

 ence to the form of the teeth. These creatures 

 have excited the most profound interest, not 

 only because they present so many important 

 differences from the members of the other 

 branch, but also, and chiefly, because it is from 

 their ranks that we are enabled to trace, with 

 no small degree of certainty, the origin of the 

 mammalia, the highest of all the Vertibrates; 

 though we can, at present, point to no known 

 form as the actual ancestor thereof. The close 

 resemblance, sometimes most striking, between 

 certain species of these ancestral reptiles and the 

 Carnivora among the mammalia, is to be put 

 down to the fact that both trace their descent 

 from the same source, and leading similar lives 

 have developed similar organs. 



As a sample of the rarity of this likeness let 

 us take a single instance, that furnished by the 

 species known as Cynognathus crateronotus of the 

 Karoo formation (Permian or Triassic) of South 

 Africa the source from which most of these 

 remarkable forms have been obtained. The 

 skull of this beast presents a quite astonishing 

 similarity, especially in regard to the teeth, to 

 that of a dog or wolf. The component elements 

 of the skull, however, and the character of the 

 vertebrae, reveal the reptilian nature of these 

 remains. The teeth of another species (Trity- 

 lodon) were of the type adapted for grinding 

 purposes, and for a long time were actually 

 believed to be those of a mammal. Further 

 pursuit of this subject would be a departure 



