CHAP. VII.] MAMMALIA OF THE NEW WORLD. 149 
and New Worlds.—Leaving the more special applications of 
palzontological evidence to be made after discussing the relations 
of the existing fauna of the several regions, we propose here to 
indicate briefly, some of the more general deductions from the 
evidence which has now been laid before our readers. 
The first, and perhaps the most startling fact brought out by 
our systematic review, is the very recent and almost universal 
change that has taken place in the character of the fauna, over 
all the areas we have been considering; a change which seems 
to be altogether unprecedented in the past history of the same 
countries as revealed by the geological record. In Europe, in 
North America, and in South America, we have evidence that a 
very similar change occurred about the same time. In all three 
we find, in the most recent deposits—cave-earths, peat-bogs, and 
gravels—the remains of a whole series of large animals, which 
have since become wholly extinct or only survive in far-distant 
lands. In Europe, the great Irish elk, the Machairodus and 
cave-lion, the rhinoceros, hippopotamus, and elephant ;—in North 
America, equally large felines, horses and tapirs larger than any 
now living, a llama as large as a camel, great mastodons and 
elephants, and abundance of huge megatheroid animals of almost 
equal size ;—in South America these same megatheroids in greater 
variety, numerous huge armadillos, a mastodon, large horses and 
tapirs, large porcupines, two forms of antelope, numerous bears and 
felines, including a Machairodus, and a large monkey,—have all be- 
come extinct since the deposition of the most recent of the fossil- 
bearing strata. This is certainly not a great while ago, geologi- 
cally ; and it is almost certain that this great organic revolution, 
implying physical changes of such vast proportions that they 
must have been due to causes of adequate intensity and propor- 
tionate range, has taken place since man lived on the earth. 
This is proved to have been the case in Europe, and is supported 
by much evidence both as regards North and South America. 
It is clear that so complete and sudden a change in the higher 
forms of life, does not represent the normal state of things. 
Species and genera have not, at all times, become so rapidly 
extinct. The time occupied by the “ Recent period,” that is the 
