CONTENTS. 



Hemichordata, 



Urochordata 



Cephalochordata, 



VERTEBRATES. 



CHAPTER XVII 



CHAPTER XVIII. 



CHAPTER XIX. 



CHAPTER XX. 



.Structure and Development of Vertebrates, 



Cyclostomata, 



Fishes, 



Amphibia, 



Reptiles, 



Birds, 



Mammals, 



CHAPTER XXI. 



CHAPTER XXII. 



CHAPTER XXIII. 



CHAPTER XXIV. 



CHAPTER XXV. 



CHAPTER XXVI. 



391 



400 



410 



421 



465 



475 



529 



560 



595 



632 



