62 



STORY OF THE AMPHIBIANS 



forms, it is said, which did not have the skull so com- 

 pletely roofed with bone. Fig. 30 is also a cut of 

 a small salamanderlike form which is, however, still 

 a labyrinthodont, when its teeth are examined. Note 

 that it has slight ribs, and that the skull-roof is com- 

 plete. It is found in the more modern upper car- 

 boniferous, and it looks as though it was getting 



Fi(.. 31. — Mmiodonsaurus Joegeri. 



near to the living kinds. But higher still and more 

 recent (in the Triassic) there lived a monster with a 

 head two feet wide and three feet long (see Fig. 

 31). It was called Mastodon saurus^ and Fig. 32 is a 

 cut of the head and jaws of Tre^natosaurus — though 

 neither were really saurians. But saurians (lizard - 

 like reptiles) and amphibians had not got so far 



