62 VERTEBRATE ANCESTORS OF MAN ? 



the Carboniferous period ; for fossil Amphibia are 

 already found in coals. 



Following our amphibian forefathers, as Haeckel 

 calls them, which retained their gills permanently, 

 there appeared other Amphibia which by metamor- 

 phosis at a later period of their life lost their gills, 

 but retained their tail. These hypothetical ancestors 

 of man forming the fourteenth stage of his line, 

 Haeckel thinks, were similar to the salamanders and 

 tritons of the present day. They originated from 

 the gilled amphibia by accustoming themselves 

 accustoming themselves, let me repeat the expression 

 at an advanced period of their life to breathe only 

 by their lungs ! Probably, they already lived in the 

 second half of the Primary time during the Permian 

 or perhaps the Carboniferous period. The proof 

 that such animals once existed is, in HaeckeFs 

 opinion, that tailed amphibia form a necessary 

 middle link between the preceding and the following- 

 stage. Let me repeat this exquisite specimen of 

 easy assumption, and evolutionary argument : * The 

 proof that sit,ch animals once existed is, that tailed 

 amphibia form a necessary middle link between the 

 preceding and the following stage / ' 



The fifteenth phylogenetic stage was represented 

 by unknown lizard-like forms, which Haeckel names 

 Protamnia, as being the forerunners of those animals 

 the embyro of which, in the course of its develop- 

 ment in ovo, is enclosed by the membrane called 

 Amnion. Their advent dates probably from the 



