SCIENCE OF FOSSIL LIFE 329 
Summary.—-The chief steps up to this time in the growth 
of the science of fossil life may now be sct forth in cate- 
gories, though we must remember that the advances pro- 
ceeded concurrently and were much intermingled, so that, 
whatever arrangement we may adopt, it does not represent 
a strict chronological order of events: 
I. The determination of the nature of fossils. Owing to 
the labors of Da Vinci, Steno, and Cuvier, the truth was estab- 
lished that fossils are the remains of former generations of 
animals and plants. 
II. The comparison of organic fossils with living forms 
that was instituted on a broad scale by Cuvier resulted in the 
conclusion that some of the fossils belong to extinct races. 
The belief of Cuvier that entire populations became extinct 
simultaneously, led him to the theory of catastrophism. ‘The 
observations of Lamarck, that, while some species disappear, 
others are continued and pass through transmutations, were 
contrary to that theory. 
III. The recognition that the stratified rocks in which 
fossils are distributed are sedimentary deposits of gradual 
formation. This observation and the following took the 
ground from under the theory that fossils had been deposited 
curing the Mosaic deluge. 
IV. The discovery by William Smith that the arrangement 
of fossils within rocks is always the same, and the relative 
age of rocks may be determined by an examination of their 
fossil contents. 
Upon the basis of the foregoing, we come to the next 
advance, viz.: 
V. The application of this knowledge to the determination 
of the history of the earth. 
Fossil Remains as an Index to the Past History of the 
Earth.—The most advanced and enlightened position that 
had been taken in reference to the fossil series during the 
