46 THE ORIGIN OF MAN 



far better developed. These were the blastids, 

 described elsewhere, and, though far less com- 

 mon, the sea-urchins known as Melonechinus. 

 Bryozoans were also characteristic of this epoch 

 as were likewise the pavement-toothed sharks but 

 which were rapidly dying out. There were many 

 kinds of cup corals and one type of compound 

 coral formed small reefs. Toward the close of 

 this period there were many kinds of amphibians 

 but as yet we know nothing of them. 



The Pennsylvanian period first saw the rise of 

 insects, but it is thought, however that they may 

 have arisen in the Devonian. They were as a 

 rule large in size and primitive in structure, and 

 led an amphibious life, their youngest or larval 

 stages being spent in the water. In general they 

 were not carnivorous animals but as they had 

 powerful chewing mouths it is thought that they 

 fed on plants and dead animal matter. They 

 had four straight wings, all alike which projected 

 sideways like those of the modern dragon flies 



