THE CARBONIFEROUS PERIOD. 



169 



which appear to commence in the Upper Silurian, are well 

 represented in the Devonian, and survive in a diminished form 

 into the Permian. The trunks of the larger species of Lepido- 



Fig. 109. Calamity cannotformls . Carboniferous Rocks, Europe and 

 North America. 



dendron at times reach a length of fifty feet and upwards, giv- 

 ing off branches in a regular bifurcating manner. The bark 



