



Produced by Robert J. Hall




THE ANCIENT LIFE-HISTORY OF THE EARTH

A COMPREHENSIVE OUTLINE OF THE PRINCIPLES AND LEADING FACTS OF
PALAEONTOLOGICAL SCIENCE


BY H. ALLEYNE NICHOLSON

M.D., D.SC., M.A., PH. D. (GOeTT), F.R.S.E, F.L.S.

PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF ST ANDREWS




PREFACE.

The study of Palaeontology, or the science which is concerned
with the living beings which flourished upon the globe during
past periods of its history, may be pursued by two parallel but
essentially distinct paths. By the one method of inquiry, we may
study the anatomical characters and structure of the innumerable
extinct forms of life which lie buried in the rocks simply as
so many organisms, with but a slight and secondary reference
to the _time_ at which they lived. By the other method, fossil
animals are regarded principally as so many landmarks in the
ancient records of the world, and are studied _historically_
and as regards their relations to the chronological succession
of the strata in which they are entombed. In so doing, it is of
course impossible to wholly ignore their structural characters,
and their relationships with animals now living upon the earth;
but these points are held to occupy a subordinate place, and to
require nothing more than a comparatively general attention.

In a former work, the Author has endeavoured to furnish a summary
of the more important facts of Palaeontology regarded in its strictly
scientific aspect, as a mere department of the great science of
Biology. The present work, on the other hand, is an attempt to
treat Palaeontology more especially from its historical side, and
in its more intimate relations with Geology. In accordance with
this object, the introductory portion of the work is devoted to a
consideration of the general principles of Palaeontology, and the
bearings of this science upon various geological problems--such
as the mode of formation of the sedimentary rocks, the reactions
of living beings upon the crust of the earth, and the sequence
in time of the fossiliferous formations. The second portion of
the work deals exclusively with Historical Palaeontology, each
formation being considered separately, as regards its lithological
nature and subdivisions, its relations to other formations, its
geographical distribution, its mode of origin, and its characteristic
life-forms.

In the consideration of the characteristic fossils of each successive
period, a general account is given of their more important zoological
characters and their relations to living forms; but the technical
language of Zoology has been avoided, and the aid of illustrations
has been freely called into use. It may therefore be hoped that
the work may be found to be available for the purposes of both the
Geological and the Zoological student; since it is essentially an
outline of Historical Palaeontology, and the student of either of
the above-mentioned sciences must perforce possess some knowledge
of the last. Whilst primarily intended for students, it may be
added that the method of treatment adopted has been so far
untechnical as not to render the work useless to the general
reader who may desire to acquire some knowledge of a subject of
such vast and universal interest.

In carrying out the object which he has held before him, the
Author can hardly expect, from the nature of the materials with
which he has had to deal, that he has kept himself absolutely
clear of errors, both of omission and commission. The subject,
however, is one to which he has devoted the labour of many years,
both in studying the researches of others and in personal
investigations of his own; and he can only trust that such errors
as may exist will be found to belong chiefly to the former class,
and to be neither serious nor numerous. It need only be added
that the work is necessarily very limited in its scope, and that
the necessity of not assuming a thorough previous acquaintance
with Natural History in the reader has inexorably restricted its
range still further. The Author does not, therefore, profess to
have given more than a merely general outline of the subject; and
those who desire to obtain a more minute and detailed knowledge
of Palaeontology, must have recourse to other and more elaborate
treatises.

UNITED COLLEGE, ST ANDREWS.

October 2, 1876.




CONTENTS.


PART I.

PRINCIPLES OF PALAEONTOLOGY.


INTRODUCTION.

The general objects or geological science--The older theories of
catastrophistic and intermittent action--The more modern doctrines
of continuous and uniform action--Bearing of these doctrines
respectively on the origin or the existing terrestrial
order--Elements or truth in Catastrophism--General truth of the
doctrine of Continuity--Ge