xiv CONTENTS 



1 



PHYLUM PROTOZOA continued. PAOE 



Class V. Infusoria . 90 



1. Example of the Class Paramwcium caudatum .... 90 



2. Classification and General Organisation 93 



Systematic Position of the Example 93 



Further Remarks on the Protozoa 103 



SECTION III 



PHYLUM AND CLASS PORIFERA [PARAZOA] 106 



1. Example of the Class Sycon gelatinosum 106 



2. Distinctive Characters and Classification 112 



Systematic Position of the Example 114 



3. General Organisation 115 



SECTION IV 



PHYLUM CCELENTERATA 129 



Class I. Hydrozoa 129 



1. Example of the Class Obelia 129 



2. General Structure and Classification 141 



Systematic Position of the Example 143 



Additional Remarks 166 



Class II. Scyphozoa 167 



1. Example of the Class Aurelia aurita 167 



2. General Structure and Classification 175 



Systematic Position of the Example 176 



Additional Remarks 183 



Class III. Actinozoa 183 



1. Example of the Class Tealia crassicornis . . . * .183 



2. Distinctive Characters and Classification 191 



Systematic Position of the Example 194 



3. General Organisation 194 



Class IV. Ctenophora 208 



1. Example of the Class Hormiphora plumosa 208 



2. Distinctive Characters and Classification 217 



Systematic Position of the Example 218 



3. General Organisation 219 



The Relationships of the Ccelenterata 223 



Appendix to the Ccelenterata The Mesozoa 227 



SECTION V 



PHYLUM PLATYHELMINTHES 232 



1. Examples of the Phylum . . 233 



i. Planaria or Dendroccelum 233 



ii. Fasciola hepatica . 236 



iii. Tcenia solium 243 



