The endeavor has been made to indicate, at the end of each chapter, the museums in which the best examples of the animals described may be seen, and also some book or article in which further information may be obtained. As this book is intended for the general reader, references to purely technical articles have, so far as possible, been avoided, and none in foreign languages mentioned.
For important works of reference on the subject of paleontology, the reader may consult "A Manual of Paleontology," by Alleyne Nicholson and R. Lydekker, a work in two volumes dealing with invertebrates, vertebrates, and plants, or "A Text-Book of Paleontology," by Karl von Zittel, English edition, only the first volume of which has so far been published. An admirable book on the vertebrates is "Outlines of Vertebrate Paleontology," by Arthur Smith Woodward. It is to be understood that these are not at all "popular" in their scope, but intended for students who are already well advanced in the study of zoölogy.
ANIMALS OF THE PAST
I
FOSSILS, AND HOW THEY ARE FORMED
"How of a thousand snakes each one
Was changed into a coil of stone."
Fossils are the remains, or even the indications, of animals and plants that have, through natural agencies, been buried in the earth and preserved for long periods of time. This may seem a rather meagre definition, but it is a difficult matter to frame one that will be at once brief, exact, and comprehensive; fossils are not necessarily the remains of extinct animals or plants, neither are they, of necessity, objects that have become petrified or turned into stone.