THE EVOLUTION OF LIFE 349 



extinct. In the following period, the Silurian, we meet 

 with the remains of fishes which, however, were very 

 different from the fishes of the present day, although 

 many of them were related to the primitive cartilaginous 

 fishes such as the sharks and rays. During the Carbon- 

 iferous era there was a great luxuriance of vegetation, 



PIG. 238. A pterodactyl, an extinct flying reptile. (After H. v. Mayer.) 



mostly belonging to primitive types related to our ferns 

 and club mosses. Much of our coal is derived from the 

 plants of the old carboniferous forests, and we can often 

 trace in pieces of coal the woody structure or the delicate 

 outline of leaves of the trees that flourished at this time. 

 In this period we find the remains of insects and am- 

 phibians, and in the following period, the Permian, we 

 meet with those of reptiles. 



It was not until the next period that the latter animals 



