216 THE HISTORY OF CREATION, 
broader and show very different structure from that seen 
in the other two orders. Probably the Fish Dragons and 
Serpent Dragons developed as two diverging branches 
out of the Primeval Dragons; but it is also possible that 
the Plesiosauria alone originated out of the Simosauria, 
and that the Ichthyosauria were lower off-shoots from the 
common stock. At all events, they must all be directly, or 
indirectly derived from the Selachii, or Primeval fish. 
The succeeding classes of Vertebrata, the Amphibia and 
the Amniota (Reptiles, Birds, and Mammals), owing to the 
characteristic structure which they all exhibit of five toes 
to each foot, may all be derived from a common primary 
form, which originated from the Selachii, and which possessed 
five toes on each of its four limbs. When we find a less 
number of toes than five, we can show that the missing 
ones must have been lost in the course of time by adapta- 
tion. The oldest known Vertebrata with five toes are 
the Batrachias (Amphibia). We divide this class into 
two sub-classes, namely, mailed Batrachians and naked 
Batrachians, the first of which is distinguished by the body 
being covered with bony plates or scales, 
The first and elder sub-class of Amphibia consists of the 
Mailed Batrachians (Phractamphibia), the oldest land 
living Vertebrata of which fossil remains exist. Well- 
preserved fossil remains of them occur in the coal, especially 
of those with Enamelled heads (Ganocephala), which are 
most closely allied to fish, namely, the Archegosaurus 
of Saarbruck, and the Dendrerpeton of North America. 
There then follow at a later period the gigantic Labyrinth- 
toothed animals (Labyrinthodonta), which are represented 
in the Permian system by Zygosaurus, but at a later 
