viii CONTENTS. 



CHAPTER IX. 



THE CHARACTERS OF GENERA 126 



CHAPTER X. 



SPECIES AND BREEDS . . .^ 134 



CHAPTER XI. 



FORMATION OF CORAL REEFS 148 



CHAPTER XII. 



AGE OF CORAL REEFS AS SHOWING PERMANENCE OF SPECIES 176 



CHAPTER XIII. 



HOMOLOGIES 201 



CHAPTER XIV. 



ALTERNATE GENERATIONS 288 



CHAPTER XV. 



THE OVARIAN EGG 269 



CHAPTER XVI. 



EMBRYOLOGY AND CLASSIFICATION 296 



