4GO THE CAUSES OF THE xi 



Florae, 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 Mega- 

 therium, and the great armadillo, the Glyptodon, 

 and so on. 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 



