THE CHORUS OF MAN’S STAGE 
pensable to support animal life, it must have coexisted 
plentifully with the earliest terrestrial animals, though 
inconspicuous in the fossil record. Fossil evidences of 
bacteria and marine algae have been found in the rocks 
laid down in the era of dawning life; but vegetation, though 
present through all preceding ages, first becomes plentiful, 
as indicated by the fossil record, in the Devonian. It is 
represented then, not only by mosses and ferns, but by 
trees of fernlike form and by some palmlike species. In 
the Carboniferous period, however, though in forms very 
strange to our eyes, vegetation became so luxuriant as to 
form the main source of the coal and to some extent of the 
oil on which modern industry depends for power. Layers 
of coal which in some sections reach a thickness of 250 
feet are supposed to represent several million years of 
luxuriant vegetation during the Carboniferous period. 
Many kinds of trees abounded, but they were very unlike 
those of the present. 
This same period brought forth in the animal kingdom 
the amphibians, those vertebrate creatures adapted to 
both land and water. They are thought by some to have 
developed from certain Devonian types of fishes. Surely 
this development is a most interesting one. It marks a 
new era in which for the first time the earth held verte- 
brate animals able to live on land. Some Carboniferous 
amphibians, recalling the structure of the crocodile, 
reached lengths of eight to ten feet. Others resembled 
snakes, lizards, and salamanders. 
Following the Carboniferous period, there ensued an age, 
evidently of great stress and hardship, called the Permian. 
It used to be supposed that life was then altogether ex- 
tinguished gnd that all subsequent life arose from a new 
creation. This is an exaggeration. Great diminution in 
life certainly occurred, and many species were extermi- 
nated. It was estimated from such knowledge as was 
available about the beginning of this century that, with 
10,000 known animal species of the Carboniferous period, 
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