CONTENTS. ix 



CHAPTER XIX. PAos 



Reprodbction 191 



CHAPTER XX. 



Development 197 



1. Metamorphosis 207 



2. Alternate Generation 211 



3. Growth and Repair 214 



4. Likeness and Variation 215 



.'). Homology, Analogy, and Correlation 217 



6. Individuality 220 



7. Relations of Number, Size, Form, and Rank 221 



8. Tlie Struggle for Life 226 



PART II.— SYSTEMATIC ZOOLOGY. 



CHAPTER XXI. 



Tun Classification op Animals 231 



Protozoa 238 



Porlfera 244 



Coelenterata 246 



ICcliinodermiita 257 



Vermes , 263 



Molliisea 269 



Arthropods 281 



Vertebrata 306 



CHAPTER XXII. 



Ststematic Aerangkment of Representative Forms. 362 



CHAPTER XXin. 



The Distribution of Animals 371 



NOTES 381 



THE NATURALIST'S LIBRARY 397 



INDEX ,.... 399 



