of Edinburgh. For alike in respect of their large
numbers, their keen intelligence, and their generous sympathy, the
members of that voluntary class yielded a degree of stimulating
encouragement, without which the labour of preparing the original
lectures could not have been attended with the interest and the
satisfaction that I found in it. My thanks are also due to Mr. R. E.
Holding for the painstaking manner in which he has assisted me in
executing most of the original drawings with which this volume is
illustrated; and likewise to Messrs. Macmillan and Co. for kindly
allowing me to reprint--without special acknowledgment in every
case--certain passages from an essay which they published for me many
years ago, under the title "Scientific Evidences of Organic Evolution."
Lastly, I must mention that I am indebted to the same firm for
permission to reproduce an excellent portrait of Mr. Darwin, which
constitutes the frontispiece.

G. J. R.

CHRIST CHURCH, OXFORD,
_April 19th, 1892._

CONTENTS

PAGE

CHAPTER I.
INTRODUCTORY 1

CHAPTER II.
CLASSIFICATION 23

CHAPTER III.
MORPHOLOGY 50

CHAPTER IV.
EMBRYOLOGY 98

CHAPTER V.
PALAEONTOLOGY 156

CHAPTER VI.
GEOGRAPHICAL DISTRIBUTION 204

CHAPTER VII.
THE THEORY OF NATURAL SELECTION 251

CHAPTER VIII.
EVIDENCES OF THE THEORY OF NATURAL SELECTION 285

CHAPTER IX.
CRITICISMS OF THE THEORY OF NATURAL SELECTION 333

CHAPTER X.
THE THEORY OF SEXUAL SELECTION, AND CONCLUDING REMARKS 379

* * * * *

APPENDIX TO CHAPTER V. 421

NOTE A TO PAGE 257 443

NOTE B TO PAGE 295 445

NOTE C TO PAGE 394 448

INDEX 451

LIST OF ILLUSTRATIONS

FIG. PAGE

1. Successive forms of Paludina, from the Tertiary deposits of
Slavonia