CONTENTS xiii 



PACK 



PHYLUM PLATYHELMIXTHES continued. 



2. Distinctive Characters and Classification . . 237 

 Systematic Position of the Examples . . 238 



3. General Organisation . 239 



4. Distribution, Mode of Occurrence, and Mutual Relationships . 263 

 Appendix to Platyhelminthes Class Nemertinea .... 268 



SECTION VI 



PHYLUM NEMATHELMINTHES . . . . 275 



Class I. Nematoda ... . 275 



1. Example of the Class Asairis lumbricoides . . 275 



2. Distinctive Characters and Classification . . 281 

 Systematic Position of the Example . . 282 



3. General Organisation ... . 283 

 Class II. Acanthocephala . . 289 

 Class III. Chatognatha . 293 



Appendix to Nemathelminthes 296 



Family Chatosomidce . . 296 



,, Echinoderidce . 296 



,, Desmoscolecidte . . . ... . 296 



Affinities and Mutual Relationships of the Nemathelminthes . 297 



SECTION VII 



PHYLUM TROCHELMINTHES . . . . 298 



Class I. Rotifera . . . 299 



1. Example of the Class Bmchionus rubens . 299 



2. Distinctive Characters and Classification . . . . 303 

 Systematic Position of the Example . . 304 



3. General Organisation . . ... 304 

 Class II. Dinophilea . . 310 

 Class III. Gastrotricha . 311 



SECTION VIII 



PHYLUM MOLLUSCOIDA. . . . 313 



Class I. Polyzoa . . . ^*, 313 



1. Example of the Class Bugula avicularia . 314 



2. Distinctive Characters and Classification . . 319 

 Systematic Position of the Example . . 320 



3. General Organisation ... . 321 

 Class II. Phoronida . . . 328 

 Class III. Brachiopoda ,331 



\ . Example of the Glass Magdlania lenticnlaris . 331 



2. Distinctive Characters and Classification . 337 



Systematic Position of the Example . . . 338 



M. General Organisation .... . . . 338 



Mutual Relationships of the Classes of the Molluscoida . . 343 



