No. 389.] THE WHITE RIVER TERTIARY. 405 
Steneofiber, confined to the probably fluviatile beds at the top 
of the White River. 
The fauna of the clays is, then, exclusively a land fauna. The 
lacustrine theory requires us to suppose that the animals were 
swept down by rivers into the lake. Modern rivers do some- 
times bring down carcasses of land animals in their floods, 
along with an overwhelmingly greater amount of tree trunks, 
leaves, etc., and mingle these with their delta deposits, form- 
ing estuarine or delta beds, a well-marked facies of sediments. 
But the White River clays are not delta deposits; they must, 
if lacustrine, ‘have been deposited far out in the open lake. 
How did the land animals get out into this open lake? The 
current could not take them out, for it was insufficient even to 
arrange the fine particles of sediment. They might conceiv- 
ably have floated out. But why in such numbers and so uni- 
formly distributed? How did separate limbs, gnawed, bitten, 
or weathered bones get there? How did the tortoises get out 
into the lake? Why were no tree trunks or plant remains 
floated out, if the animal carcasses could float out? Why are 
there no fish or invertebrate remains? Contrast this fauna 
with the Cretaceous, where marine reptiles, fish, and inverte- 
brates are exceedingly numerous, amphibious and land animals 
extremely rare, and plant remains by no means common. Con- 
trast it with known lacustrine deposits, as some of the small 
Pleistocene lakes of the east, where fresh-water invertebrates 
are very abundant, fresh-water fish common, and land plants 
or water plants, or both, often make up a large part of the 
deposits, while land animals are rare, except in peat bogs. 
. If, then, the White River clays are lacustrine, they must have 
been deposited in an absolutely lifeless sea, surrounded by a 
well-watered region devoid of vegetation, yet sustaining an 
animal population of incredible density. And even this com- 
bination of improbabilities cannot account for some facts, and 
does not satisfactorily account for others. 
