CONTENTS. ix 



CHAPTER XIX. page 



Reproduction 191 



CHAPTER XX. 



Development 197 



1. Metamorphosis 207 



2. Alternate Generation 211 



3. Growth and Repair . .. 214 



4. Likeness and Variation 215 



5. Homology, Analogy, and Correlation ... 217 



6. Individuality 220 



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



8. The Struggle for Life 226 



PART II.— SYSTEMATIC ZOOLOGY. 



CHAPTER XXI. 



The Classification of Animals : 231 



Protozoa 238 



Spongida 244 



Coelenterata... 246 



Echinodermata 257 



Vermes 263 



Mollusca 269 



Arthropoda 281 



Tunicata 305 



Vertebrata 306 



CHAPTER XXII. 



Systematic Arrangement of Representative Forms 362 



CHAPTER XXIII. 



The Distribution of Animals 371 



NOTES 381 



THE NATURALIST S LIBRARY 397 



INDEX 399 



A* 



