THE ANCIENT LIFE-HISTORY OF THE EARTH

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


BY H. ALLEYNE NICHOLSON

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

PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF ST ANDREWS




PREFACE.

The study of Palæontology, 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,