THE ORIGIN OF MAN 53 



amphibians were known as Stegocephalia, a term 

 which means covered or mailed head and has ref- 

 ence to the fact that the upper surface of the 

 skull was roofed over by more or less thick dermal 

 bones which were often much sculptured. As the 

 reptilia developed out of the Stegocephalia, a 

 brief description will be necessary. 



Some were small and active, with well devel- 

 oped walking legs and relatively short tails ; some 

 were active swimmers, with long tails; others of 

 medium size were thickset and sluggish in habit; 

 while a few had the appearance of being gigantic 

 and almost legless. Their heads were usually 

 broad and flat, with very wide mouths almost the 

 full width of the skull, but in some forms the 

 heads were more or less elongated. They lived 

 not only in fresh waters, but unlike their descend- 

 ants also in brackish ones. Most of them were 

 probably carnivorous and fed on shell-fish, worms 

 and other water invertebrates, but more particu- 

 larly on fishes, reptiles and small members of 



