80 
HAROLD’S DISCUSSIONS. 
pigeon family, and weighed fifty pounds, was once 
found in Mauritius, but passed away less than two 
Imndred years ago. 
The patrefelis was doubtless the father of all cats. 
The sword-toothed tiger and the cave bear were rep¬ 
resentatives of the Carnivora. In one cave alone the 
skeletons of a thousand bears were found, besides 
those of elephants, tigers, lions, and rhinoceroses. 
The monkeys became the tree-dwellers of the latter 
part of the age; the bison began to roam over the 
prairies, and horses in large herds grazed on the green 
slopes undisturbed by man’s presence. 
The earth was prepared for nourishing cereals 
and luscious fruits. We may anticipate another 
change, a new being; nor are we disappointed, for 
the age of mind is about to begin. 
GLACIAL EPOCH. 
The age of mammals came to a close in an entire¬ 
ly new way. A great sheet of ice slowly advanced 
from the north, both in this country and in Europe. 
The evidences and effects of it have been described in 
Book lY. In New England it must have been a mile 
thick, and perhaps two miles in the Hudson Bay 
region. From that point it flowed outward, in obe¬ 
dience to the law of viscid bodies. 
Some think the cause of this ice sheet was a 
change in position of the earth’s axis, but this theory 
is not generally accepted. Others think it was due 
to land elevations, particularly in the north, which 
caused not only high altitudes but a change in the 
