THEIR DEPOSITS AND DRAINAGE. 651 
Behring's Straits; and thus the two kindreds have been 
growing, and flowering, and seeding, and dying in each col- 
ony far beyond the reach of the other, and developing their 
peculiarities each in its own way from generation to genera- 
tion. When now we come to compare the present flora of 
China and Japan with that of the eastern half of our conti- 
nent we find the strongest proofs of their intimate relation- 
ship. Many of the species are identical, while others are 
but slightly changed and, on the whole, the differences are 
less than such as have grown out of separation in human 
kindred colonies in an infinitely shorter period. 
Among the great mammals that formerly inhabited our 
continent but such as are now extinct, there were some which 
seem to have bid defiance to the changes I have detailed. 
These were particularly the mastodon and elephant, both of 
which were probably capable of enduring great severity of 
climate. The mammoth we know was well defended from 
the cold by a thick coat of hair and wool, and was probably 
capable of enduring a degree of cold as severe as that in 
Which the musk-ox now lives. We know that both these 
great monsters —the elephant and mastodon — continued to 
inhabit the interior of our continent long after the glaciers 
had retreated beyond the upper lakes, and when the minutest 
details of surface topography were the same as now. This 
is proven by the fact that we not unfrequently find them em- 
bedded in peat in marshes which are still marshes where 
they have been mired and suffocated. It is even claimed 
that here, as on the European continent, man was a cotem- 
porary of the mammoth, and that here as there, he contrib- 
uted largely to its final extinction. On this point, however, 
more and better evidence than any yet obtained is necessary 
before we can consider the cotemporaneity of man and the 
elephant in America as proven. The wanting proof may be 
Obtained to-morrow, but to-day we are without it. 
. The pictures which geology holds up to our view of North 
America during the Tertiary ages, are in all respects but 
AMER. NATURALIST, VOL. IV. 83 
