ACALEPHÆ 195 Medusadæ 213 Rhizostoma 219 Vilelladæ 229 Ctenophora 254 CHAPTER IX. ECHINODERMATA 259 Asterias 260 Crinoidea 270 Echinidæ 280 MOLLUSCA. GENERAL DEFINITION 301 CHAPTER X. MOLLUSCOIDA 303 Tunicata 309 Ascidians 309 CHAPTER XI. ACEPHALOUS MOLLUSCA 316 CHAPTER XII. ACEPHALOUS MOLLUSCA 344 Mytilidæ 344 CHAPTER XIII. CEPHALOUS MOLLUSCA 391 Their Characteristics 391 CHAPTER XIV. PULMONARY GASTEROPODS 396 Limnæidæ 397 Buccinidæ 428 Purpura 430 Pterocera 439 CHAPTER XV. MOLLUSCOUS PTEROPODS 441 CHAPTER XVI. CEPHALOPODOUS MOLLUSCA 445 Tentaculifera 445 Acetabula 448 CHAPTER XVII. CRUSTACEANS 477 General Definition 477 Crabs and Crayfish 486 Lobsters 496 CHAPTER XVIII. FISHES 502 CARTILAGINOUS FISHES 508 Cyclostomata 508 Selachia 510 Sturiona 524 CHAPTER XIX. OSSEI, OR BONY FISHES 529 Plectognathi 529 Lophobranchii 534 Malacopterygii 536 Abdominales 560 Acanthopterygians 590 Pharyngeans 596 ILLUSTRATIONS. PLATE PAGE I. THE ARGONAUT SAILING BEFORE THE WIND (_Frontispiece_) 467 II. SPONGE FISHING ON THE COAST OF SYRIA 78 III. CORAL FISHING ON THE COAST OF SICILY 138 IV. CORAL ISLAND IN THE POMOTOUAN ARCHIPELAGO 169 V. SEA ANEMONES (I.) 187 VI. SEA ANEMONES (II.) 189 VII. AGALMA RUBRA 239 VIII. GALEOLARIA AURANTIACA 244 IX. SEA-URCHINS 290 X. FISHING FOR HOLOTHURIA 295 XI. SYNAPTA DUVERNAEA 299 XII. DREDGING FOR OYSTERS 374