OP CREATION. 129 



to the frog as the nearest analogue by many strik- 

 ing anatomical peculiarities. 



The Labyrinthodon must indeed be placed at the 

 head of the Batrachian order ; for, in dimensions and 

 in general organization, it was far the most important 

 animal of the whole group. The upper surface of the 

 skull was broad, and flattened like that of the alli- 



Fig. 50 



LABYRINTHODON. 

 (Left Side of Lower Jaw with Teeth.) 



gator, and its outer surface was deeply sculptured. The 

 jaws were powerful, and armed with sharp teeth, the 

 number of which was very great (probably upwards 

 of a hundred on each side of each jaw). The teeth 

 diminished in size towards both ends, but especially 

 towards the muzzle, where, however, there were also 

 much larger teeth, like tusks, reminding one in this 

 arrangement of what is seen in the crocodiles. 



The skin in at least one species seems to have been 

 covered with bony plates. The mode of respiration, 

 and hence, probably, the shape and use of the ribs, 

 offered a still further approximation to the higher 

 reptiles ; but still, in many essential points, the Ba- 

 trachian character is clearly to be traced, while the 

 shape and general structure of the vertebrae points 

 rather to the lower organization of fishes. 



But the extremities offer the most interesting sub- 

 ject for consideration. They are partly crocodilian, 



G 5 



