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 IL—SYSTEMATIC ZOOLOGY. 
CHAPTER XXI. 
The Classification of Animals ....... 231 
Protozoa. 238 
Porifera........... 244 
Coelenterata........... 246 
Echinodermata........... 257 
Vermes.............. 263 
Mollusca... 269 
Arthropoda..... 281 
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 
