CONTENTS XV 



PAGE 



Phylum Platyhelminthes — miitiniml. 



2. Distinctive Characters and Classification . . . . 251 

 Systematic Position of the Examples ... . 253 



3. General Organisation . ... . . . 254 



4. Distribution, Mode of Occurrence, and Mutual Relationships . 283 

 Appendix to Platyhelminthes — Class Nemertinea . . 288 

 Distinctive Characters and Classification . 295 



SECTION VI 



Phylum Nemathelminthes . . . . 297 



Class I. Nematoda ... ... 297 



1. Example of the Class — Ascarin Inmhricoides . . 297 



2. Distinctive Characters and Classification . 303 

 Systematic Position of the Example . . . . 304 



3. General Organisation . .... 305 

 Class II. Acanthocephala . . ... 312 

 Class III. Chsetognatha .... . 316 



Appendix to Nemathelminthes . . . . . . 319 



Family Chcetoso'midce . 319 



,, Echinoderidce . . ... 319 



,, Desmoscolecidce ... ... 320 



Affinities and Mutual Relationships of the Nemathelminthes . 320 



SECTION VII 



Phylum Tkochelminthes 322 



Class I. Rotifera . . . .... 323 



1. Example of the Class — Brachionus rubens 



2. Distinctive Characters and Classification 

 Systematic Position of the Example 



3. General Organisation . 

 Class II. Gastrotricha 



. 323 



. 327 

 329 



. 330 



. 335 



Appendix to Trochelminthes — Binophilea and Histriohdellea, . 336 



SECTION VIII 



Phylum Molluscoida 340 



Class I. Polyzoa . .340 



1. Example of the Class — Bugula avicularia . ... 341 



2. Distinctive Characters and Classification . 347 

 Systematic Position of the Example . . 348 



3. General Organisation ... . . 348 

 Class II. Phoronida ... 355 

 Class III. Brachiopoda . . ... 360 



1. Example of the Class — Magellania lenticularis . 360 



2. Distinctive Characters and Classification 366 

 Systematic Position of the Example . .... 367 



3. General Organisation 367 



Mutual Relationships of the Classes of the Molluscoida . . 372 



