264 EVOLUTION AND THE PRESENT AGE 
saurus, with body one hundred feet long and tail as 
stout as a ship’s mast, dragged his unwieldy length 
over the plains of Montana, while in every latitude 
and clime you would come upon similar cold-blooded 
dinosaurs, sometimes bigger than elephants, sometimes 
as small as mice, stalking through the landscape or 
burrowing underground, sitting upright, kangaroo 
fashion, with heads near the tree-tops, flying about 
in the gloaming with bat-like wings like a schooner’s 
mainsail, or sailing in the seas with long crane-like 
necks reared aloft above the water. Those were long 
days, but they too passed, and the years are millions 
since the last dinosaur perished. And then, to men- 
tion just one more, we are introduced to an Eocene 
world, about which the most striking things are the 
appearance of deciduous trees alongside of the ever- 
greens, the vast and varied development of beautiful 
forms and colours simultaneously in the insect world 
and in the world of flowers, and lastly, the presence 
of sundry queer-looking, warm-blooded mammals cal- 
culated to produce in an observer the state of mind of 
old Polonius, for one would seem like a pig were it 
not also something like a small donkey, another would 
seem about midway between cat, rabbit, and monkey, 
all of them being generalized types which have since 
been variously specialized. I need not add that these 
creatures, too, are all gone. 
Now in view of such repeated and wholesale de- 
struction of life, it was not strange that the geologists 
of a hundred years ago should have imagined a succes- 
sion of dire catastrophes involving a large part or the 
whole of the earth’s surface. It was supposed that 
the beginning and end of every great geologic period 
