460 THE CAUSES OF THE XI 
Flore, unless you have reason to believe there 
has also been a great lapse of time or a great 
change of conditions. The animals, for instance, 
of the newest tertiary rocks, in any part of the 
world, are always, and without exception, found 
to be closely allied with those which now live in 
that part of the world. For example, in Europe, 
Asia, and Africa, the large mammals are at pres- 
ent rhinoceroses, hippopotamuses, elephants, lions, 
tigers, oxen, horses, &c.; and if you examine the 
newest tertiary deposits, which contain the 
animals and plants which immediately preceded 
those which now exist in the same country, you 
do not find gigantic specimens of ant-eaters and 
kangaroos, but you find rhinoceroses, elephants, 
lions, tigers, &c.,—of different species to those now 
living—but still their close allies. If you turn to 
South America, where, at the present day, we have 
great sloths and armadilloes and creatures of that 
kind, what do you find in the newest tertiaries ? 
You find the great sloth-like creature, the MJega- 
therium, and the great armadillo, the Glyptodon, 
and soon. And if you go to Australia you find 
the same law holds good, namely, that that con- 
dition of organic nature which has preceded the 
one which now exists, presents differences perhaps 
of species, and of genera, but that the great types 
of organic structure are the same as those which 
now flourish. 
What meaning has this fact upon any other 
