of the
ancient lake beds, records of the age of mammals had been made and
preserved with a fulness surpassing that of any other known region on
earth. The profusion of vertebrate remains brought to light was almost
unbelievable. Prof. Marsh, who was first in the field, found three
hundred new tertiary species between 1870 and 1876, besides unearthing
the remains of two hundred birds with teeth, six hundred flying dragons,
and fifteen hundred sea serpents, some of them sixty feet in length. In
a single bed of rock not larger than a good sized lecture room, he found
the remains of no less than one hundred and sixty mammals.

It was this work which Prof. Cope took up and carried forward. Its
importance may be appreciated when it is stated that among these
remains are found examples of just such intermediate types of organisms
as must have existed if the succession of life on the earth has been an
unbroken lineal succession. Here are snakes with wings and legs, and
birds with teeth and other snakelike characteristics, bridging the gap
between modern birds and reptiles. The line of descent of the horse, the
camel, the hippopotamus and other mammals has been traced to a single
ancestor, the result being the proof of the theory of evolution.

The whole work of American paleontology has, of course, been along these
lines. Agassiz himself was a living and vital force in it, as were such
men as Joseph Leidy and H. F. Osborne.

* * * * *

It is a remarkable fact that one of the few truly original and novel
ideas the past century can boast, and the one which has had the deepest
influence on geology, had its origin in the brain of an illiterate Swiss
chamois hunter named Perraudin. Throughout the Alps, on lofty crags,
great bowlders were often found, which had no relation to the geology of
the region and which were called erratics, because they had evidently
come there from a distance. But how? Scientists explained it in many
ways, but it remained for the mountaineer to suggest that the bowlders
had been left in their present positions by glaciers. The scientific
world laughed at the idea, but ten years later, it was brought to the
attention of Louis Agassiz; he investigated it, became a convert, and
saw that its implications extended far beyond the Alps, for these
erratic bowlders were found on mountains and plains throughout the
northern hemisphere. Agassiz found everywhere evidences of glacial
a