292 KANSAS CITY REVIEW OF SCIENCE. 
knowledge of the true feature of the animals, which pervaded its oceans, 
swamps and forests. We have probably a small list of its plants, but no one 
supposed that dicotyledons flourished in that era. The labors of the past thirty 
years have tended to push back in geological strata some forms, but has not 
shown a change of type. Reptiles are now known to be older than when our 
list was half as numerous, but the forms are no lower. The pines are now 
gathered from the upper Silurian, when not long ago we had found them no lower 
than the Upper Devonian. But the normal trunk, fruit and cell form do not 
differ from the two horizons. 
While in every locality some breaks are found in the geological deposits, 
yet the missing portions, to a very great extent, are seen in other countries. In 
Russia there is a blank between the upper Carboniferous and Permian, but in 
Kansas and Nebraska no such imperfection occurs, and the fossils pass from the 
lower of the one to the higher strata of the other. The great divisions of the 
geological formations in Europe are not tne same as those in America. ‘The 
three epochs of the Tertiary in the former, become four in the latter, thus help- 
ing the defective record. Some of the American are fresh water deposits, 
synchronous with those of the salt water of Europe. According to Cope and 
Hayden, there is an unbroken continuation of the deposits of the Cretaceous 
and Tertiary ages, ‘‘establishing an uninterrupted succession of life across what 
is generally regarded as one of the greatest breaks of geologic time.” * * * 
Types of lizards and tortoises continue, like the crocodiles, from the Mesozoic to 
Tertiary time without extraordinary modification of structure.” 
But this ‘‘ uninterrupted succession of life,” connecting these two ages, 
covers the spot where we should find the missing links, which should, according 
to the theory of evolution, show the ancestry of all our extremely diversified 
mamal life of the early Eocene; yet, not a trace of any has been found. ‘The 
great variety from Lemur to Marsupial, in the latter formation, demanded nearly 
as much variance of form in the connecting deposits, and thence shading back- 
ward to the primitive type as low as the Ornithorynchus. 
Those who contend that our mammals are derived from a more simple 
quadruped should produce the facts which show it. Should true mammals or a 
high connecting form of marsupials be hereafter discovered below the Eocene 
it will then be soon enough to consider what theory they will sustain. We 
apprehend that they will be more likely to show forms as diverse from each 
other as the members of the Tertiary fanna. 
The Wealden epoch in England and similar deposits in the ‘‘ Foot-Hills” of 
Colorado very nearly cover the chasm which exists in other parts of the world 
between the Jurassic and Cretaceous. ‘Thus we have a continuous succession of 
land through that portion of the earth’s history in which are the records of all 
the highest members of the animal and vegetable world. 
Our American fourteen divisions of the Silurian and nine of the Devonian 
U.S. Geological Survey of Colorado, 1873, p. 442, Hayden. 
