PART IV Contents xi 



CHAPTER XV 



BACKBONELESS ANIMALS 



1. Sponges — 2. Stinging ■ animals or Ccelenterata — 3. '^Worms'' — 

 4. Echinoderms — 5. Arthropods — 6. Molluscs . Pages 222-247 



CHAPTER XVI 



BACKBONED ANIMALS 



I. Balanoglossus — 2. Tunicates — 3. The Lancelet — 4. Round-mouths 

 or Cyclostomata — 5. Fishes — 6. Amphitians — 7. Reptiles — 8. 

 Birds — 9. Mammals ..... 248-272 



PART IV 



The Evolution of Animal Life 



CHAPTER XVII 



THE EVIDENCES OF EVOLUTION 



1. The idea of evolution — 2. Arguments for evolution : Physiological, 

 Morphological, Historical — 3. Origin of life . . 273-281 



CHAPTER XVIII 



THE EVOLUTION OF EVOLUTION THEORIES 



I. Greek philosophers — 2. Aristotle — 3. Lucretius — 4. Evolutionists 

 before Darwin — 5. Three old masters : Buf/bn, Erasmus Darwin, 

 Lamarck — 6. Darwin — 7. Darwin's fellow - workers — 8. The 

 present state of opinion .... 282-302 



CHAPTER XIX 



THE INFLUENCE OF HABITS AND SURROUNDINGS 



1. The influence of function — 2. The influence of surroundings — 3. 

 Our own environment . . . . 303-319 



