CONTENTS xiii 

 CHAPTER VII 



PAGE 



Phylum Platyhelminthes 150 



1 . A Fresh-water Flatworm — Planaria . . . .150 



2. Class I. Turbellaria 155 



3. Class II. Trematoda 157 



a, The Liver Fluke — Fasciola hepatica, 157; b, Tre- 

 matoda in General, 161. 



4. Class III. Cestoda . ....... 163 



a, The Tapeworm — Tcenia, 163 ; b, Cestoda in General, 

 165. 



5. FHtworms in General 166 



CHAPTER VIII 



Phylum Nemathelminthes 169 



1. A Parasitic Round Worm — Ascaris himbricoides . .169 



2. Nemathelminthes in General 173 



CHAPTER IX 



Invertebrates of More or Less Uncertain Systematic 



Position 176 



1. Mesozoa 176 



2. Nemertinea 177 



3. Nematomorpha . . . . . . . . 179 



4. Acanthocephala 180 



5. Chaetognatha 180 



6. Rotifera 181 



7. Bryozoa 183 



8. Phoronidea . . 185 



9. Biachiopoda 185 



10. Gephyrea 186 



CHAPTER X 



Phylum Echinodermata 189 



1. Anatomy and Physiology of the Starfish — Asterias . 190 



2. Class I. Asteroidea — Starfishes 198 



