CONTENTS ix 



44. Definitions 142 



45. The History of Taxonomy 143 



Chapter 8 



THE PHYLUM PROTOZOA 148 



46. Introduction 148 



47. Organelles 149 



48. Class Flagellata 152 



49. Class Sarcodina 157 



50. Class Ciliata 160 



51. Class Suctoria 165 



52. Class Sporozoa 165 



53. Reproduction in the Protozoa 166 



54. Relationships among the Protozoa 169 



Chapter 9 



THE PHYLUM PORIFER.\ 172 



55. Introduction 172 



56. General Characteristics 172 



57. The Classes of Sponges 175 



58. Reproduction 178 



Chapter 10 



THE PHYL.\ COELEXl ERATA AND CTEXOPHORA 181 



59. Introduction 181 



60. Gonionemus: General Behavior 181 



61. Gonionemus: Feeding and Digestion 184 



62. Gonionemus: Diffusion 186 



63. Gonionemus: Nervous System 187 



64. Gonionemus: Reproduction 188 



65. Classes of the Phylum Coelenterata 189 



66. Class Hydrozoa 190 



67. Class Scyphozoa 192 



68. Class Anthozoa 195 



69. FreshAVater Coelenterates: Hydra 198 



70. The Phylum Ctenophora 199 



71. The Regulation of Form 201 



Chapter 11 



THE PHYLUM PLATYHELMINTHES 204 



72. Dugesia: Habitat and Appearance 204 



73. Dugesia: Feeding and Digestion 204 



