TABLE OF CONTENTS 



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I. GENERAL CONSIDERATIONS ON ANIMAL FORM i 



A. Descriptive Terms i 



B. Planes and Axes i 



C. Symmetry i 



D. Metamerism or Segmentation a 



E. Cephalization 3 



F. Homology and Analogy 3 



II. THE PHYLUM CHORDATA 5 



A. The Characteristics of the Chordates . . . 5 



B. The Characteristics of the Vertebrates 5 



C. The Classification of the Chordates 5 



III. GENERAL STUDY OF TYPICAL CHORDATES 9 



A. A mphioxus 9 



B. A Tunicate n 



C. Balanoglossus 14 



D. Anatomy of a Lamprey 14 



E. External Anatomy of the Dogfish 16 



F. External Anatomy of the Skate 18 



G. External Anatomy of a Teleost 19 



H. Some Ganoid Fishes 21 



I. External Anatomy of Necturus 22 



J. External Anatomy of a Lizard 23 



K. External Anatomy of the Turtle 24 



L. External Anatomy of the Pigeon 25 



M. External Anatomy of a Mammal * . 27 



N. Summary 29 



IV. GENERAL FEATURES OF CHORDATE DEVELOPMENT 3 1 



A. The Chordate Egg 31 



B. The Cleavage of the Egg and the Formation of the Blastula .... 32 



C. Formation of the Gastrula 34 



D. Formation of the Third Germ Layer, the Neural Tube, and the Notochord 36 



E. Further History of the Mesoderm 39 



F. The Fate of the Ectoderm 41 



G. The Fate of the Entoderm . 41 



H. The Fate of the Mesoderm and the Formation of Mesenchymc ... 42 



V. THE COMPARATIVE ANATOMY OF THE INTEGUMENT AND THE EXOSKELETON . 45 



A. General Considerations on the Skeleton 45 



B. The Structure of the Skin 45 



C. The Exoskeleton in General 47 



D. Exoskeleton of Fishes 47 



E. Exoskeleton of Amphibia S 



F Exoskeleton of Reptiles 5 



dii 



