and the place of the testimony of the rocks in the doctrine of evolution
without knowing much about the geological history of the earth and the
influences at work in the past. For these reasons palæontology differs
somewhat from the other divisions of zoölogy where direct observation
gives the materials for arrangement and study; in this case the individual
data, that is, the fossil fragments themselves, can be made available only
through a knowledge of their exact situations, of the reasons for their
occurrence in particular places in the rock series and of the way rocks
themselves are constructed and worked over by natural agencies. Our task
is therefore twofold: certain physical matters of a geological nature must
first be investigated before the biological facts can be described.

No doubt most people feel justified in believing that the whole doctrine
of evolution must stand or fall according to the cogency of the
palæontological evidences. Plain common sense says that the owners of
shelly or bony fragments found in the deeply-laid strata of the earth must
have lived countless years ago, and if the evolutionist asserts that
primitive organic forms of ancient times have produced changed descendants
of later times, it would seem that fossil evidence would be supremely and
overwhelmingly important. It is true, of course, that this evidence is
peculiarly significant, because in some ways it is more direct than that
of the other categories already outlined. But it must not be forgotten
that the doctrine is already securely founded upon the basic principles of
anatomy and embryology. Science must treat the data of this category by
different methods and must view them in different ways. Therefore we are
interested in palæontology because of the way it tells the story of
evolution in its own words, and because we are justified in expecting that
its account should include a description of some such order of events as
that revealed by the developing embryos of modern organisms and that
demonstrated by the comparative anatomy of the varied species of adult