CONTENTS 



?AOB 



Preface, 3 



Introduction : The General Principles of Biology, . 9 



Chap. I. — The Distinctive Characters of Animals, . . , .44 



II.— The Protozoa, 73 



III. — The Porifera and the Ccelenterata, 102 



IV. — The Turbellaria, the Rotifera, the Trematoda, and the 



Cestoidea, ISV 



V. — The Hirudinea, the Oligoch^ta, the Polych^ta, the 



Gephyrea, 189 



YI. — The Arthropoda, 219 



VII.— The Air-breathing Arthropoda, 320 



VIII.— The Polyzoa, the Brachiopoda, and the Mollusca, . . 389 



IX. — The Echinodermata, 466 



X. — The Tunicata or Ascidioida, 510 



XI. — The Peripatidea, the Myzostomata, the Enteropneusta, 

 the Ch^etognatha, the Nematoidea, the Physemaria, 

 the Acanthocephala, and the Dicyemida, . . . 534 

 XII. — The Taxonomy of Invertebrated Animals, .... 561 

 Index, 589 



