CONTENTS. 



IX 



VERTEBRATES. 



CHAPTER XVII. 



HEMICHORDA 



CHAPTER XVIII. 



UROCHORDA 



CHAPTER XIX. 



CEPHALOCHORDA 



CHAPTER XX. 



STRUCTURE AND DEVELOPMENT OF VERTEBRATES 



CHAPTER XXI. 



CYCLOSTOMATA . 



CHAPTER XXII. 



FISHES 



CHAPTER XXIII. 



AMPHIBIA 



CHAPTER XXIV. 



REPTILES 



CHAPTER XXV. 



BIRDS 



CHAPTER XXVI. 



MAMMALS 



PAGE 

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424 



439 



453 



496 



508 



558 



590 



625 



667 



