CONTENTS. xi 



PAGE 



CHAPTER XX. 



Cyclostomata. 

 Petromyzon and Myxine, . . . . .402 



CHAPTER XXI. 



Pisces. 



General Characters— Life of Fishes— Types : Skate, Haddock, 

 Herring— Elasmobranchii— Dipnoi— Ganoidei — Teleostei — 

 Contrasts between the Orders of Fishes, . . 410 



CHAPTER XXII. 



Amphibia. 



General Characters — Life of Amphibians — Type : the Frog — 

 Classification of Amphibia — Anura — Urodela — Gymno- 

 phiona — Labyrinthodontia, ... . 443 



CHAPTER XXIII. 



Reptilia. 



General Characters — Chelonia — Rhynchocephalia — Lacertilia 



— Ophidia — Crocodilia — Extinct Types, . . 468 



CHAPTER XXIV. 



AVES. 



The Life of Birds — General Characters — Development of the 



Chick — Type : the Pigeon — SaururEe — Ratita; — Carinatze, 492 



