C. A. White—fossil Faunas and Floras. 371 
allowed the successive evolution of the faunas in question. 
We must therefore assume that at least the Puerco and Wa- 
satch mammalia were developed somewhere else, and that they 
were respectively transferred to the region in which their re- 
mains are now found. 
The Puerco fauna is so unique in character that, with our 
present limited knowledge of it, and our present methods of 
paleontological study, it appears to mark an epoch in the his- 
tory of vertebrate life of North America of which the inverte- 
brate and plant remains, and the stratigraphical condition of 
the series of deposits in which they occur, give no indication. 
At present also we know nothing of the immediate ances- 
try of the Wasatch mammalian fauna, but in view of its highly 
developed, diversified and distinctive character, we must con- 
clude that it existed somewhere, possessing essentially the same 
characteristics which its known remains now exhibit, long 
before the earliest Wasatch strata were deposited. ‘The strati- 
graphical conditions before referred, to indicate so short a time 
for the deposition of the strata within the vertical range of 
which the remains of these three faunas are found, that it also 
seems necessary to conclude that the Wasatch fauna existed 
somewhere contemporaneously with the Puerco mammalia 
from which it differs so much, and also contemporaneously 
with the Laramie dinosaurs, from which it differs far more 
widely. The conclusion therefore seems to be irresistible that 
the faunal types which are regarded as diagnostic of the Hocene 
period existed contemporaneously with those which are equally 
diagnostic of the Cretaceous period. 
That faunas and floras of Cretaceous and Tertiary types 
should have existed contemporaneously is not strange, for a 
similar diversity now exists as regards the living faunas and 
floras of different parts of the world; and they have doubtless 
existed in a greater or less degree ever since animals and plants 
came to be widely differentiated. It is strange, however, that 
this latter fact should be so often ignored in discussions of the 
relative ages of extinct faunas and floras. 
The foregoing remarks are confined mainly to cases in which 
continental faunas and floras are compared with each other, 
and with reference to the usually accepted paleontological 
standard. The following remarks are made with reference 
to the fossil faunas and floras of the great intra-continental 
deposits of North America, as compared with those of presum- 
ably contemporaneous sea coast deposits. -Kver since the pub- 
lication of my views as to the inland character of the sea in 
which the strata of the Laramie Group were deposited, they 
seem to have been accepted without serious question; and the 
purely fresh-water character of the deposits which succeeded 
