xiv TABLE OF CONTENTS 



PAGE 



G. Exoskeleton of Birds 52 



H. Exoskeleton of Mammals 54 



I. Summary : 55 



VI. THE ENDOSKELETON: THE COMPARATIVE ANATOMY OF THE VERTEBRAL COLUMN 



AND RIBS 57 



A. General Considerations on the Endoskeleton 57 



B. The Embryonic Origin of the Vertebrae and Ribs 58 



C. Some Primitive Vertebral Columns 63 



D. The Vertebral Column of the Dogfish 64 



E. Vertebral Column of Teleosts 67 



F. Vertebral Column of Amphibia 68 



G. Vertebral Column of Reptiles 70 



H. Vertebral Column of Birds 72 



I. Vertebral Column of Mammals 73 



J. Summary of the Vertebral Column and Ribs 76 



VII. THE ENDOSKELETON: THE COMPARATIVE ANATOMY OF THE GIRDLES, THE 



STERNUM, AND THE PAIRED APPENDAGES 78 



A. General Considerations 78 



B. The Pelvic Girdle and the Posterior Paired Appendages 79 



C. The Pectoral Girdle, the Sternum, and the Anterior Paired Appendages . 85 



D. General Summary of the Girdles, the Sternum, and the Paired Appendages 94 



VIII. THE ENDOSKELETON: THE COMPARATIVE ANATOMY OF THE SKULL AND THE 



VISCERAL SKELETON 96 



A. The Cartilage Stage of the Skull 96 



B. The Visceral Skeleton 99 



C. The Formation of the Membrane Bones of the Skull 100 



D. The Formation of the Cartilage Bones of the Skull and the Composition of 



the Complete Skull 103 



E. The Skull of Necturus, a Partially Ossified Skull 107 



F. The Skull of the Alligator, a Typical Modern Skull 112 



G. The Bones of the Mammalian Skull 116 



H. General Summary of the Skull and Visceral Skeleton 126 



IX. THE COMPARATIVE ANATOMY OF THE MUSCULAR SYSTEM 128 



A. General Considerations 128 



B. The Muscles of the Dogfish 128 



C. The Muscles of Necturus 130 



D. The Muscles of the Cat and Rabbit 133 



E. Summary 157 



X. THE COMPARATIVE ANATOMY OF THE COELOM, DIGESTIVE, AND RESPIRATORY 



SYSTEMS 158 



A. The Origin and Parts of the Coelom and the Mesenteries .... 158 



B. The Digestive Tract and Its Derivatives 159 



C. The Coelom, Digestive, and Respiratory Systems of Elasmobranchs . . 163 



D. The Coelom, Digestive, and Respiratory Systems of Necturus . . . 168 



E. The Coelom, Digestive, and Respiratory Systems of the Turtle . . . 172 



F. The Coelom, Digestive, and Respiratory Systems of the Pigeon . . . i?6 



