423 ELEMENTARY GEOLOGY 
way, the forests with which we are now acquainted 
(Fig. 244). 
Not only were the trees of the forest different, but 
no birds existed among them, and the hum of the 
familiar insects could not be heard. Some progress 
among the insects is noted, but there is a rather close 
Fic. 242. 
Group of Carboniferous plant fossils from near coal beds. 
(1, Pecopteris miltoni (a fern) ; 2, Alethopteris serlii (a fern) ; 3, Lepidodendron . 
clypeatum; 4, Sigillaria mammillaris.) 
resemblance between the insect fossils of Devonian and 
Carboniferous times. Many more species and individ- 
uals have been discovered in the Carboniferous rocks, 
mainly because when the plants were preserved, the 
insects that lived upon and in them were also buried 
and handed down as fossils. 
