THE EVOLUTION QF MAN 



lower vertebrates than mammals, we are carried 

 even beyond the scaly reptiles into the ranks of 

 amphibians with naked skins. 



In distinction from reptiles, such as lizards, 

 snakes, crocodiles and turtles, the amphibians 

 embrace newts, toads and frogs. While these 

 animals do not have any hair, they nevertheless 

 have peculiar little sense organs precisely in 

 those places of the skin which, among mammals, 

 carry hair and which correspond pretty closely in 

 their arrangement to the plan of the hairy cover- 

 ing of embryos among mammals. According to 

 the biogenetic law, this might very well indicate 

 that the amphibians still show to-day the primi- 

 tive form of a genuine hairy covering. We 

 might well conclude from this fact that the most 

 ancient mammals, for instance, those creatures 

 belonging to the duckbill family which we dis- 

 cover in the first third of the saurian period, the 

 so-called Trias, are not descended from genuine 

 reptiles, but rather from amphibians which oc- 

 cupy a still lower position in the system. 



Now, it happens that the living representatives 

 of amphibians still possess many a detail which 

 might be regarded as an indication of the direct 

 descent of mammals from them. It is remarka- 

 ble that many frogs and toads have very signifi- 

 es 



