xiv CONTENTS 



PAGE 



3. Class II. Ophiuroidea Brittle Stars .... 199 



4. Class III. Echinoidea Sea Urchins .... 202 



5. Class IV. Holothurioidea Sea Cucumbers . . . 205 



6. Class V. Crinoidea Sea-lilies or Feather-stars . . 208 



7. Development of Echinoderms . . . . . .210 



8. Artificial Parthenogenesis . . . . . .212 



9. The Position of Echinoderms in the Animal Kingdom . 213 



CHAPTER XI 



PHYLUM ANNELIDA 215 



1. The Earthworm Lumbricus 215 



2. Classification of Annelids ...... 231 



3. Class I. Archiannelida 232 



4. Class II. Chsetopoda 233 



5. Class III. Hirudinea 236 



6. Annelids in General ....... 240 



CHAPTER XII 



PHYLUM MOLLUSCA 242 



1. The Pearly Fresh-water Mussel Anodonta and the 



Uniones ......... 243 



2. Class I. Amphineura . . . . . . .251 



3. Class II. Gastropoda 252 



a, A Land-snail, 253 ; b, Gastropoda in General, 258. 



4. Class III. Scaphopoda 261 



5. Class IV. Pelecypoda . . . . . . . 261 



6. Class V. Cephalopoda 264 



a, The Common Squid Loligo, 264 ; b, Cephalopoda 

 in General, 267. 



7. Mollusca in General . . 269 



CHAPTER XIII 



PHYLUM ARTHROPODA . . . . . . . . . 274 



i. Introduction . . . . . . . . , 274 



