CHAPTER IV.

HOW THE BACKBONED ANIMALS PASS FROM WATER-BREATHING TO AIR-BREATHING, AND FIND THEIR WAY OUT UPON THE LAND 70

PICTURE-HEADING--A Carboniferous Forest with ancient Amphibians (Labyrinthodonts). In the water _Baphetes_; on land _Dendrerpeton_, _Hylonomus_, and _Hylerpeton_. (Animals taken from Dawson’s _Air-Breathers of the Coal_.)