THE CARBONIFEROUS PERIOD. 
91 
tlie Silurian and Devonian periods. The Car- 
boniferous marshes were not without their rep- 
tilian inhabitants ; but they were Reptiles of the 
lowest class, the so-called Amphibians, those 
which are hatched from the egg in an immature 
condition, undergoing metamorphosis after birth. 
They have no hard scales, and lay a large num- 
ber of eggs. I am unable to present any figure 
of one of these ancient Reptiles, as they are 
found in so imperfect a state of preservation that 
no plates have been made from them. I would 
add, in connection with this subject, that I believe 
a large number of animals found in the Carbon- 
iferous deposits, and referred to the class of Rep- 
tiles, to be Fishes allied to Saurians. 
Before leaving the Carboniferous period, let us 
see what territory the United States has con- 
quered from the Ocean during that time. All its 
central portion, from Canada to Alabama, and 
from Western Iowa, Missouri, and Arkansas to 
Eastern Virginia, was raised above the water. 
But as yet the Alleghanies and the Rocky Moun- 
tains did not exist ; a great gulf ran up to the 
mouth of the Ohio, for the Mississippi had not 
yet accumulated the soil for the fertile valley 
through which it was to take its southern course ; 
the Coral-Builders had still their work to do in 
constructing the peninsula of Florida : and, in- 
deed, all the borders of the continent of North 
