144 MR. darwin's work and 



point, the singular likeness which obtains between the 

 successive Faunae and Florae, whose remains are pre- 

 served on the rocks : you never find any great and 

 enormous difference between the immediately succes- 

 sive Faunse and 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 present rhinoceroses, 

 hippopotamuses, elephants, lions, tigers, oxen, horses, 

 &c. ; and if you examine the newest tertiary deposits, 

 which contain the animals and plants which im- 

 mediately 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 difii'erent 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 Megatherium, 

 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 condition of organic nature 

 which has preceded the one which now exists, pre- 

 sents 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 hypo- 



