LIST OF ILLUSTRATIONS 
PAGE 
Front End of Thread-Worm, . . 449 
Development of Thread-Worm, . . 450 
Vinegar-Eel, . . . .451 
Iihabditis and Rhabdonema, . .451 
Humble-Bee Thread-Worm, . . 452 
Human Round Worm, . . . 453 
Head of Round Worm, . . . 453 
Human Thread-Worm, . . . 454 
Dochmius duodenalis, . . . 454 
Head of Cucullanus elegans, . . 454 
Trichinosis Worm Coiled Up, . . . 455 
Trichina sjpiralis, . ... 455 
Larvae of Gordius, ... 456 
Eggs and Larva of Mermis, . . 456 
Arrow-Worm, . . . .457 
Proboscis of Tetrastemma, . . . 457 
Four-Eyed Nemertine ( Tetrastemma), . 458 
Cross-Bearing Nemertine, on a Coral, . 459 
A Nemertine ( Pterosoma ),. . . 460 
Pilidium Larva, with Nemertine Worm, . 461 
Human Tape-Worms, . . . 461 
Egg and Embryo ( Proscolex ) of Tape- 
Worm, .... 462 
Bladder-Worm Stage ( Cysticercus ) of Tape- 
Worm, .... 462 
Tcenia echinococcus, . . . 463 
Broad Tape-Worm, . . . 463 
Trematode Worms, . . . 464 
Life-History of Double-Worm, . . 465 
Dactylocotyle and Anthocotyle, . . 466 
Polystomum and Larva, . . . 467 
Liver-Fluke and Larva, . . . 467 
Development of Distomum, . . 468 
Larval Form of Liver-Fluke, . . 468 
Mesostomum tetragonum, . . . 469 
Trematodes, . . . .470 
Schizostoma production, . . . 470 
Single-Eyed Turbellarian ( Stenostomum ),. 471 
Structure of a Dendrocoelian, . .472 
Smooth Polycelis, . . . .472 
Two-Striped Geodesmus, . . . 472 
Planarian Worm ( Planaria ), . .472 
Tufted Planarian ( Thysanozoum), . . 473 
Rhopalura, ..... 473 
A Dicyemid, .... 473 
Cydippe, . . . . .476 
Venus’ Girdle, . . . .478 
Stinging Capsules,.... 480 
Physophora, .... 482 
Stephalia, ..... 483 
Clavatella, ..... 485 
Pedis, ..... 485 
Corymorpha, with Detached Medusae, . 486 
Monocaulus, . . . 487 
XV 
PAGE 
Group of Hydradinia, . . . 488 
Hydradinia on a Whelk-Shell, . . 480 
Millepora, ..... 490 
Hydra Monster, Artificially Produced, . 491 
Chrysaora, ..... 492 
Rhizostoma, .... 493 
Periphylia, ..... 494 
Tessera, ..... 495 
Monoxenia darwini, . . . 496 
Development of Monoxenia, . . 497 
Sections of Monoxenia, . . . 498 
Outline of Caulastrcea, . . . 499 
Larvae of Sea-Anemone, . . . 500' 
A Sea-Anemone {Actinia), . . 501 
Endive-Leaved Anemone,. . . 502 
Short-Tentacled Anemone, . . 502 
Parasitic Anemone ( Palythoa), on Glass- 
Rope Sponge, .... 503 
Palythoa axinellce, .... 504 
A Simple Coral ( Thecocyathus ), . . 505 
Scarlet Crisp Coral ( Flabellum ), . . 505 
Mushroom-Coral ( Fungia ), . . 506 
A Deep-Sea Coral ( Leptopenus ), . . 506 
A Branching Coral ( Dendropliyllia ), . 507 
A Madrepore Coral ( Madreporia), . 507 
A Massive Coral ( Astroides), . . 508 
Developmental Stages of Astroides, . 509 
A Star-Coral ( Astrcea ), . . . 509 
A Brain-Coral ( Meandrina ), . . 510 
Mouths of Brain-Coral, . . .510 
A Horny Coral ( Antipathes), . . 510 
An Alcyonarian Coral ( Alcyonium ), . 512 
A Sea-Pen ( Pteroicles ), . . . 513 
Umbellula thompsoni, . . . 514 
Umbellula encrinus, . . .514 
A Sea-Fan {Gorgonia), . . .515 
Corkscrew Sea-Fan {Streptocaulus), . 516 
Red Coral, . . . . .517 
Organ-Pipe Coral (Tubipora), . . 517 
Structure of Tubipora, . . .517 
Island with Fringing- and Barrier-Reefs, 520 
Coral-Island, or Atoll, . . . 521 
Section through a Coral-Reef, . . 522 
Diagram Explaining Theory of Subsidence, 524 
Outline of the Island of Aiva, . . 524 
Mouths of Madrepore, . . . 525 
Bread-Crumb Sponge, Showing Currents, 526 
Flagellated Chambers of Sponges, . 527 
Sponges Growing on Seaweed, . . 528 
Carpenter’s Glass-Sponge, . . 530 
Structure of Venus’ Flower-Basket, . 532 
An Ascon Sponge,.... 532 
Structure of Toilet-Sponge, . . 533 
Calcareous Ascon Sponge ( Leucosolenia ), . 534 
