LIST OF ILLUSTRATIONS. XI 



PACK 



WHIPTAIL .... 288 



SKELETON WHEEL-BEAKER 2-43 



SWORD-BEARER 247 



TRIPOD WHEEL-BEARER 249 



TWO-LIPPED TUBE-WHEEL 252 



WHEELS OP TUBE-WHEEL 253 



FOOT OP NAIS 262 



THROAT OF LEECH LAID OPEN . . . . . . 269 



JAW OF LEECH 270 



PUSHING-POLES OF SERPULA 273 



HOOKS OF SERPULA 274 



SPIXE OF ECHINUS 281 



HEAD OF PBDICELLARIA TRIDENS 284 



SUCKER OF URCHIN 289 



PORES OF URCHIN 289 



SUCKER-PLATE OF URCHIN 292 



DUMB-BELLS IN HOLOTHURIA 298 



WHEEL IN CHIRODOTA 298 



ANCHOR- PLATE IN SYNAPTA 299 



LARVA OF SEA-URCHIN 303 



YOUNG SEA-URCHIN : DEVELOPMENT OF DISK . . . .305 



CYDIPPE . . . % 310 



SARSIA 316 



THAUMANTIAS. 319 



OTOLITHES OF THAUMANTIAS 320 



TURRIS AND ITS YOUNG 324 



LAOMEDEA 328 



TENTACLE OF LAOMEDEA 329 



STAURIDIA ' . .342 



LARES 345 



POLYPES OF Cow's PAP 351 



SPICULA OF Cow's PAP 353 



PORTION OF ACONTIUM 357 



CINCLIDES 358 



CNIDA OF MADREPORE 364 



CNIDA OF TEALIA 367 



CMDA OF CORYNACTIS 370 



FORMS OF AMCEBA . . 379 



