LIST OF ILLUSTRATIONS 11 



Head of Cheese-Mite 253 



Brachionus 265 



Mouth of Brachionus ". 267 



Whiptail 273 



Skeleton Wheel-Bearer 276 



Sword-Bearer 283 



Tripod Wheel-Bearer 283 



Two-Lipped Tube- Wheel 287 



Wheels of Tube-Wheel 288 



Foot of Nais 298 



Throat of Leech laid Open 306 



Jaw of Leech (in part) 308 



Pushing-poles of Serpula 310 



Hooks of Serpula 312 



Spine of Echinus ; 319 



Head of Pedicellaria Tridens 322 



Sucker of Urchin 327 



Pores' of Urchin... 327 



Sucker-plate of Urchin 330 



Dumb-bells in Holothuria 337 



Wheel in Chirodota 338 



Anchor-plate in Synapta 339 



Larva of Sea-Urchin 343 



Young Sea-Urchin (Development of Disk) 345 



Cydippe 352 



Sarsia % .. . 359 



Thaumantias 361 



Otolithes of Thaumantias 363 



Turris and its Young 867 



Laomedea 871 



Tentacle of Laomedea (flattened) 373 



Stauridia 887 



Lares 889 



Polypes of Cow's-Pap 396 



Spicula of Cow's-Pap 399 



Portion of Acontium ;, 402 



Cinclides. . . 404 



