Chapter I · NDEX

Acanella, as host, 298 Acanthobdella, 395 Acanthocephala, 123, 124, 174 f.; embryology, 179; classification, 181 Acanthocotyle, 73 Acanthodrilidae, 357, 362, 381, 383, 384 Acanthodrilus, 356, 363, 366, 372, 382, 384; chaetae, 350 Acanthozoon, 20 Accessory gut, of Polychaeta, 305 Aceros, 19 Achaeta, 445 Acholoe, 297 Aciculum, 247; fossil, 302 Acmostoma, 50 Acoela, 42; occurrence and habits, 43; reproduction, 47; classification, 49 Acotylea, 16 f., 17, 18 Acrorhynchus, 49; occurrence, 44 Actinotrocha larva, 458 Actinurus, 201, 222 Acyclus, 221 Adaptation, of Trematodes, 52, 62; of Cestodes, 74; of Nematodes, 161 Adherent, 523 Adineta, 204, 222, 227 Adventitious avicularia, 482 Aeolosoma, 349, 353, 354, 360, 370, 374, 375 Aetea, 518, 525 Agassiz, on Syllidae, 280 Alaurina claparedii, 49 Albertia, 204, 210, 213, 224, 227 Alciope, 315 Alciopids (Alciopina), 314; head, 263; parapodium, 265; habit, 291; light-organs, 294 Alciopina parasitica, 298 Alcyonella, 494, 505, 518 Alcyonellea, 518 Alcyonidium, 477, 480, 492, 518, 532; structure of zooecium, 469; reproduction, 507, 508; larva, 510, 511 Alimentary canal—see Digestive System Alitta, 317 Allantonema, 131, 150, 151, 161 Allman, on Polyzoa, 474, 475 Alloeocoela, 43; habits, 46; reproduction, 47; classification, 50 Alloiogenesis, 66 n. Allolobophora, 351, 367, 369, 371, 386, 389, 390 f.; cocoons, 365 Allostoma pallidum, 50 Alluroides, 379 Allurus, 351, 366, 370, 389; cocoons, 365 Alma, 352 f., 387 Alternation of generations, 66, 81, 281 Amathia, 481, 518, 532 Ammocharidae, 258, 325 Ammotrypane, 273, 331; intestine, 271 Ampharete, 330 Ampharetidae, 258, 330 Amphibia, Trematodes of, 55, 62, 71, 72; Nematodes of, 163 Amphichaeta, 377 Amphicoerus, 49 Amphicora, 339 Amphicorine, gill, 261 Amphicorinidae, 258, 339 Amphicteis, 330 Amphictenidae, 258, 330 Amphiglena, 273, 339 Amphileptus, 235 Amphilina, 91 Amphinome, eye of, 255; A. smaragdina, colour, 293 Amphinomidae, 258, 318; shape, 259; caruncle, 260, 273 n.; head, 262, 263; parapodium, 264; cirri, 265; chaetae, 267, 267; in Lepas, 297 Amphiporus, 102, 114; British species, 110 Amphiptyches, 77 Amphistomatidae, 73 Amphistomum, 71, 73; A. hominis, 63 Amphitrite, 327, 328; gill, 329 Ampullaria, Temnocephala with, 53 Anachaeta, 350, 376, 395 Anal, cirri, 259; funnel, 259, 332, 333; vesicles, 358, 436 Anangian worms, 253 Anarthropora, 529 Ancylostomum, 143, 163 Andrews, on Sipunculus, 417, 426 Angiostomum, 134 Angler-fish, Trematodes of, 62, 72 Anguillula aceti, 125, 154; A. tritici, 125; A. diplogaster, 155 Anguillulidae, 137, 154 Anguinella, 532 Annadrilus, 386 Annelida, 241 Anocelis, 42 Anonymidae, 19 Anonymus, 16, 18, 19, 20; penes, 27 Anopla, 109 Anoplocephala, 91; characters, 90: A. mamillana, 90; A. perfoliata, life-history, 83; specific characters, 90: A. plicata, specific characters, 90 Anoplodiscus, 73 Anoplodium, 50; A. parasiticum, occurrence, 45 Antaeus, 388 Antedon, as host, 342 Antenna, of Rotifers, 215 Anthobothrium, 76 n., 91 Anthocotyle, 73 Antinoë, 298 Antipathes, as host, 298 Anuraea, 225, 226 Anuraeidae, 201, 205, 225, 226 A'oon, an edible worm, 297 Apel, on Priapuloidea, 433 Aperture, of zooecium, 468, 517, 523, 524 Aphaneura, 353, 374 Aphanostoma, 49 Aphanostomatidae, 49 Aphelenchus, 131, 155, 157 Aphrodite, 312; shape, 258; head, 260; peristomium, 263; chaetae, 268; felting, 312; intestine, 271; genital cells, 273; colour, 291: A. aculeata, 312; distribution, 299; A. echidna, 299 Aphroditidae, 258, 309; frontal ridge, 260; parapodium, 264; elytra, 266, 309; chaetae, 266 Apical plate, of Trochosphere, 245 Apodina, 235 Apodoides, 225 Apogon, Scolex polymorphus in, 77 Apsilidae, 201, 203, 214, 220, 221 Apsilus, 201, 212, 213, 214, 221 Arabellites, 302 Arachnidium, 532 Archiannelida, 241; anatomy, 243 f.; nerve cords, 255; development, 243, 245 Archigetes, 5, 74, 76, 91; significance of, 77 Area, of zooecium, 523, 524 Arenicola, 333; perienteric sinus, 252; nephridium, 253, 254, 269; prostomium, 259; body, 259; head, 264; gill, 265; chaetae, 266 f.; genital organs, 273; otocyst, 273; burrows, 285; pigment, 291; colour, 293; A. marina, 333; habits, 301; in brackish water, 284; as bait, 297; eggs, 314 Arenicolidae, 258, 333 Argilophilus, 372 Arhynchidae, 185 Arhynchus hemignathi, 181, 185 Aricia, otocyst, 273; eggs, 275 Ariciidae, 258, 321; gill, 265 Aristotle, on Earthworms, 347 Armata, 445, 446 Arthropoda, absence of cilia in, 124 Articulata, 517, 518 Ascaridae, 131, 138, 163 Ascaris, 139, 163; A. acus, 130; A. alata, 140; A. depressa, 141; A. ferox, 141; A. incurva, 141; A. leptoptera, 141; A. lumbricoides, 125, 134, 135, 139, 163; A. megalocephala, 125, 127, 128, 131, 136, 140, 163; A. mucronata, 141; A. mystax, 125, 130, 140; A. nigrovenosa, 155; A. rubicunda, 141; A. suillae, 139; A. sulcata, 141; A. transfuga, 125, 126, 141 Ascodictyon, 521 n. Ascomorpha, 223 Ascopodaria, 488 n. Asellus, Rotifers attached to, 227 Asexual reproduction, in Triclads, 40; in Rhabdocoels, 44; in Cestodes, 80; in Trichoplax and Salinella, 96; in Polychaeta, 278 f., 279, 280, 282, 340; in Oligochaeta, 374, 375, 377; in Polyzoa, 496, 514 Aspidobothridae, 73 Aspidocotyle, 73 Aspidocotylea, 73 Aspidogaster, 63, 73 Aspidosiphon, 421, 423, 424, 425, 428; commensalism of, 429 Asplanchna, 200, 205, 210, 213, 215 n., 223, 226 Asplanchnaceae, 203, 212, 220, 222 Asplanchnidae, 200, 201, 203, 205, 211, 212, 216, 223, 226, 230 Asplanchnopus, 201, 211, 222, 223, 226, 230 Ass, parasites of, 140 Association, of Rhabdocoels with Lamellibranchs and Sea-urchins, 45; of Monotus fuscus with littoral animals, 46; significance, in Turbellaria, 51—see also Commensal and Parasitic Asteroids, as hosts, 341 Asterope, 315 Astropecten, as host, 297, 309 Atokous phase, 277 n. Atractonema, 131, 150, 152, 153 Atrium (genital), in Planaria, 38, 39; in Oligochaeta, 361, 378 Atrochus, 201, 213, 214, 221 Auditory organs, of Turbellaria, 26; of Hoplonemertea, 106, 110; of Nematoda, 128; of Polychaeta, 273 Aulastomum, 393, 399, 403 Auricles, of Rotifers, 205 Autolytus, 308; eye, 255; denticles, 270; brood-sac, 275, 276; reproduction, 278, 279; sexual dimorphism, 281; A. ebiensis, eggs, 276 Automolos, British species, 50 Avenella, 533 Avicularian zooecium, 482, 524 Avicularium, 466, 467, 468, 482 f., 482, 516, 517, 522 f., 524; adventitious, 482; vicarious, 482; vibraculoid, 484, 485; structure, 483; movements, 485; function, 486 Axine, 56, 73 Axiothea, 332, 333 Baely, on human parasites, 139 Baird, on Oligochaeta, 382 Bait, Polychaeta as, 297 Baker, on Rotifers, 197, 207; on Polyzoa, 496 n. Balanoglossus, affinities of Nemertinea with, 120 Balatro, 204, 212, 224, 227 Balfour, on Trochosphere, 229 Barentsia, 488 n. Barrois, on Polyzoa, 509 Basement-membrane, of Leptoplana, 11, 12; of Nemertines, 102, 103, 110 f. Bathymetrical distribution, of Polychaeta, 300 Bdellodrilus, 376 Bdelloida, 201, 203 f., 211, 213, 215, 216, 222, 227 Bdellouridae, 32, 42 Beania, 518, 525 Beddard, on Tetrastemma aquarium dulcium, 118; on Oligochaeta, 347 f.; on Leeches, 392 f. Bedwell, on Rotifers, 198 Beneden, van, on Cestodes, 76; on Nematodes, 162; on Phoronis, 450 Benham, on a fresh-water Tetrastemma, 118; on Archiannelida, 241 f.; on Polychaeta, 245 f.; on Myzostomaria, 341 f.; on Oligochaeta, 357, 373, 382; on Phoronis, 452 f. Benhamia, 383 f. Bicellaria, 481, 518, 526, 527 Bilfinger, on Rotifers, 212 Bilharzia, 4, 73; B. crassa, 70; B. haematobia, 63, 68 f., 69 Bimastos, 389 Bipaliidae, 35, 42 Bipalium, 33, 34, 42, 408 Birds, Trematodes of, 62, 63, 64, 72; Cestodes of, 77 f., 84, 85; Nematodes of, 144, 149, 163; Gordius of, 173; Acanthocephala of, 184, 185 Bisexual, Turbellaria, 44; Trematodes, 70 f. Bladder, of Rotifers, 214 Bladder-worms, 5, 79 f., 89 Blanchard, on Cestoda, 91; on Hirudinea, 392 f., 405, 408 Blastomeres, of egg of Distomum, 65 Blood, of Nemertinea, 108; of Polygordius, 244; of Chaetopoda, 252; of Chlorhaemidae, 252, 334; of Magelona, 252, 325; of Sabelliformia, 252, 337 Blood-corpuscles, in Chaetopoda, 252 Body-cavity (including Coelom), of Nematoda, 130; of Gordius, 166; of Acanthocephala, 175, 178; of Chaetognatha, 187; of Archiannelids, 243, 244; of Polychaeta, 249; of Myzostoma, 343; of Oligochaeta, 355; of Leeches, 397; of Gephyrea, 416; of Phoronis, 454, 462; of Polyzoa, 468, 488, 495 Body-wall, of Nemertinea, 102, 103; of Nematodes, 125; of Gordiidae, 165; of Acanthocephala, 175; of Chaetognatha, 187; of Rotifers, 205; of Nereis, 249; of Oligochaeta, 349; of Gephyrea, 414, 436; of Phoronis, 454; of Polyzoa, 470, 495, 500 Bohadsch, on Gephyrea, 411 Bohemilla, 377; chaeta, 350 Bonellein, 435, 292 Bonellia, 411, 434, 442; anatomy, 434 f., 435; male, 438; development, 439; habits of, 442; as host, 297 Bonnet, on Oligochaeta, 348, 379 Boring Worms, 286, 287 Borlase, on Lineus marinus, 99 Borlasia elizabethae, 111, 114 Bothriocephalidae, 91 Bothriocephalinae, 91 Bothriocephalus, 91; B. cordatus, 81, 91; B. cristatus, 81, 91; B. latus, in man, 81, 91; life-history, 84; reproductive organs, 87 f.; larva, 87; B. mansoni (= B. liguloides), 81, 91 Bothriocerca, 226 Bothrioneuron, 379 Bothrioplana, 46, 50 Bothrioplanidae, 42, 46, 50 Bothromesostoma personatum, 49 Bourne, on Oligochaeta, 352, 373, 377 n., 380; on Leeches, 400 Bouvier, on commensal Gephyrea, 429 Bowerbankia, 470, 480, 481, 492, 500, 518, 532, 533; larva, 511, 513; budding, 514 Brachionidae, 225 Brachionus, 200, 201, 204, 218, 225, 226, 227 Brachydrilus, 357 Brackish water, Rotifers, 226; Polychaeta, 284; Polyzoa, 492 Bradynema, 150, 151, 160 Braem, on statoblasts, 503 f. Brain—see Nervous System Branchellion, 393, 395, 397, 401, 406 Branchial crown, 336; regeneration of, 283 Branchiobdella, 376 Branchiomma, 337; gills, 261; eyes, 272; B. vigilans on Aphrodite, 299 Branchiura, 352, 361, 367, 378 f.; transverse section, 353 Braun, on Platyhelminthes, etc., 6 n., 55 n., 62, 94 Brettia, 525, 527 Bristles = Chaetae, q.v. Bristle-worms, 241 British, Polycladida, 19; Tricladida, 42; Rhabdocoelida, 49; Nemertinea, 100, 110 f.; Polychaeta, 306 f.; Earthworms, 390; Leeches, 393; Gephyrea, 449; Polyzoa, 488 n., 505, 523 f. Brood-pouch, of Spirorbis, 261, 276, 341; of Salmacina, 276; of Entoprocta, 487, 507 Brood-sac, of Autolytus, 275; of Myrianida, 280 Brown body, in Polyzoa, 468, 471 f., 472, 489, 496, 510, 514 Brown tubes (nephridia), of Sipunculoidea, 415, 417, 423, 425; of Echiuroidea, 435, 437, 439, 441; of Epithetosomatoidea, 445; used as generative ducts, 418, 438; absent in Priapuloidea, 430 Bryozoa, 475 Buccal region, in Polychaeta, 249, 250, 269; of Nereis diversicolor, 248; of N. cultrifera, 316 Buchanan, on marine muds, 423 Buchholzia, 359 Budding, in Syllidae, 279, 283 (see also Gemmation); in Polyzoa, 467, 514 (see also Polypide-bud) Bugula, 467, 468, 477, 481, 515, 517, 518, 519, 526; avicularia, 483, 485; larva, 511 Bunge, on respiration in Nematoda, 130 Bürger, on Nemertinea, 109, 112; on Nectonema, 168; on Hirudinea, 397, 403 Burrows, of Polychaeta, 285, 304; of Cirratulus, 286; of Nereis, 286, 316, 317; of Arenicola, 333; fossil, 302; of Earthworms, 368; of Sipunculus, 426 Bursa seminalis, in Rhabdocoels, 48 Busk, on Polyzoa, 465 n., 475, 487, 519 Buskia, 533 Bütschli, on Nematoda, 137 Byrsophlebs, occurrence, 44; British species, 49 Caberea, 487, 518, 526; vibracula, 486, 517 Caecum, in Polyzoa, 499 Calathus, host of Gordius, 172 Calceostominae, 73 Calceostomum, 73 Caldwell, on Phoronis, 454, 456, 461 Calicotyle, 73 Callidina, 201, 202, 204, 218, 219, 222, 225, 227, 230 Calliobothrium, 76 n., 91; larva, 77 Calotte, of Dicyemids, 93 Calyx, 488 Camerano, on development of Gordius, 170 Capitella, 331; peristomium, 263; special chaetae, 267, 268; habitat, 286; colour, 291; O. capitata, distribution, 299 Capitellidae, 258, 331, 373 Capitelliformia, 258, 305; guanin in, 253; body, 259; buccal region, 269; siphon, 272; ciliated organs, 272, 273; genital organs, 273 Carabus, host of Gordius, 172 Carinella, 112; British species, 112 Carinellidae, side organs of, 107 Caruncle, of Amphinomidae, 260, 273 n., 318 Caryophyllaeus, 91; C. mutabilis, 77 Castalia, 308; distribution of, 300 Castings, of Polychaeta, 285; fossil, 302; of Arenicola, 333 Castrada, 44, 49 Cat, parasites of, 80, 125, 130, 140, 143, 144, 145 Catenicella, 518, 519 Catenula, 49 Cathypna, 225 Cathypnidae, 225 Cellaria, 479, 515, 518, 519, 526; zooecia and avicularium, 482 Cellepora, 518, 527, 528, 529; avicularia, 483, 517 Celleporella, 529 Cellularia, 518, 527 Cellularina, 518 Cement-glands, of Rotifers, 205 Cephalic slits, of Nemertinea, 101, 104, 107, 111, 112 Cephalisation, in Polychaeta, 263; in Oligochaeta, 377 Cephalodiscus, 461 f. Cephalopods, parasites of, 78, 92; list of, containing Dicyemids, 94 Cephalosiphon, 205, 221 Cephalothrix, 112 Cercaria, 13, 65, 67, 71 f.; C. macrocerca, 72; C. cystophora, 72 Cercyra, 42 Cerebral organ, of Nemertinea, 107; of Gephyrea, 417 Cerebratulus, 101, 111, 114; British species, 111 Cerfontaine, on Earthworms, 349, 350 Cestoda, characters of the group, 5, 74; nature of, 76 f.; occurrence, 77-82; life-histories, 83; structure and development, 84-89; synoptic table of, 89 f.; classification, 91 Cestodariidae (= Monozoa), 91 Cestoplana, 17, 18, 19 Cestoplanidae, 19 Chaetae, 241; of Polychaeta, 266, 267; provisional, 274; of Nereis, 246, 247; of Heteronereid, 276, 277; jointed, 246; natatory, in sexual Syllid, 278, 307; iridescent, 268, 291, 312; palmate, of Coabangia, 339 n.; colour, 291; genital, of Capitella, 331; of Sternaspis, 336; special, of Polydora, 261, 267; of Chaetopterus, 267, 324; of Myzostoma, 342; of Oligochaeta, 347, 350, 351, 352; penial, 362; of Microdrili, 375 f.; of Megadrili, 381 f.; of Lumbricidae, 389, 390; of Leeches, 395, 396; (= hooks), of Echiuroid Gephyrea, 434, 435, 438, 440 f., 446 Chaetifera, 445, 446 Chaetobranchus, 352 Chaetogaster, 356, 377, 401 Chaetognatha, 186 f., 534; anatomy, 186; development, 189; habits, 189; classification, 191; key to, 193; American species, 534 Chaetonotus, 232, 235 Chaetopoda, 241 f.; as food for Nemertinea, 115 Chaetopteridae, 258, 323 Chaetopterus, 304 n., 323; anatomy, 323 f.; special chaetae, 267; larva, 274, 325; pigment, 292; phosphorescence, 295, 296; commensals of, 298, 478, 533; Ch. variopedatus, 324 Chaetosoma, 158 Chaetosomatidae, 158 Chaetosyllis, form of head, 278 Chaetozone, 326; uncini, 268 Chaetura, 235 Chalk, Serpulids of, 301 Charles, on male guinea-worm, 148 Cheilostomata, 477, 506, 518, 519, 525, 526 f.; occurrence, 478; external characters (see also Avicularium and Vibraculum), 481; ovicells, 507; reproduction, 507 f.; larva, 511; fossil, 521 Chiaje, Delle, on Gephyrea, 411 Chickoff, on Triclads, 41 Chironomus, host of Gordius, 172 Chitin, 249, 267; in coelomic corpuscles, 252 Chloeia, colour, 291 Chlorhaemidae, 258, 305, 334, 336; chlorocruorin in, 252; head, 260, 262, 264; palps, 260; tentacles, 262 Chlorocruorin, 252, 334; colour due to, 291 Chone, 338 Chorizopora, 530 Cilia, 3; of Leptoplana, 10, 11, 12, 15; of Polyclads, 23, 25, 26; of Müller's larva, 29; of Land Planarians, 33; of Planaria lactea, 35; of Temnocephala, 53; of Trematode-larvae, 3, 59, 60, 65; of Cestode-larvae, 87; absent in certain groups, 124, 396; of Rotifers, 202 f.; of Archiannelida, 243, 244; of Echiuroidea, 434; of Phoronis, 453; of Polyzoa, 467, 470 Ciliated, lappets, of Pterosyllis, 273 n.; pits, of Polygordius, 244; pits (= nuchal organs), of Polychaeta, 272 f.; organs, of Capitelliformia, 305 Cingulum, in Rotifers, 202 Cirratulidae, 258, 325; gill, 265; tentacular filaments, 304 n. Cirratulus, 326; burrows, 286; pigment, 292; colour, 293; viviparous, 276; C. tentaculatus, 326 Cirri, of Nereis, 246; of Polychaeta, 265; of Myzostoma, 342; anal, 259; nuchal, of Eunicidae, 318; peristomial, of Nereis, 248; nerves to, 254; of Polychaeta, 263 Cladocora, with Myxicola, 294 Claparède, on Heteronereis, 276, 277; on Earthworms, 347, 355, 356 Claus, on Nematoda, 138; on Seisonaceae, 225 n. Clepsine—see Glossiphonia Clitellio, 366, 378 Cloeosiphon, 424, 425, 429 Clover sickness, 155 Clymene, 333; C. ebiensis, tube of, 287 Clymenidae—see Maldanidae Coabangia, 284, 339 n. Cobb, on Nematoda, 131 n., 138 Cobbold, on Nematoda, 140 Cobitis, host of Gordius, 173 Cochleare, 225 Cocoons, of Triclads, 40; of Oligochaeta, 364, 365; of Leeches, 404 Coelom—see Body-cavity Coelomic fluid, of Polychaeta, 252; as cause of colour, 291 Coelopus, 225 Cohn, on Rotifers, 198 Collar, peristomial, of Sabellidae, 336; of Gephyrea, 421; of Ctenostomata, 470, 477, 480, 481 Colonial nervous system, 471 Colony, of Myrianida, 281; of Syllis ramosa, 282; of Polyzoa, 466 Colour of Polyclads, 20; of Land Planarians, 33; of Nemertinea, 102; of Polychaeta, 291, 314, 340 Coluridae, 207, 225 Colurus, 225, 226 Comatula, as host, 342 Commensal, Polychaeta, 297 f., 323, 325; Gephyrea, 428, 429; Polyzoa, 489 Conn, on development of Gephyrea, 419 n., 441, 444, 447 Conoceros, 19 Conochilus, 202, 203, 205, 215, 221, 226 Conocyema, hosts of, 94 Convoluta, 45; British species, 43, 49; C. henseni, pelagic habit, 43; C. roscoffensis, assimilating tissue, 43 Copepoda, on Polychaeta, 299 Copeus, 215, 224 Coral reefs, Polychaeta in, 293 Corallina (= Coralline Alga), 14, 488, 516 Coralline, 465 Coralline Crag, 465, 521 Corallobothrium, 91 Corethra, host of Gordius, 172 Cori, on Phoronis, 451 f. Cornulites, 302 Cotylea, 16 f., 17, 18 Cotylogaster, 73 Cotyloplana, 35 Crateromorpha, as host, 282 Crayfish, Temnocephala associated with, 53 Creeper, 317 Crepina, 450 Cretaceous, Polyzoa, 520, 521 Cribrilina, 518, 524, 528 Crinoids, as hosts, 341 Criodrilus, 358, 366, 386 Crisia, 471, 478, 479, 480, 507, 518, 531 Crisiidae, 517 Crisp, on Parasites, 164 Cristatella, 494 f., 495, 499, 501, 503-505, 512, 518; attacked by Planarians, 486; movements, 494, 496, 498; fission, 496, 506; statoblast, 502, 503; larva, 512 Crossopodia, 302 Crotchets, 266, 267, 305, 322 Crustacea, parasites of, 174, 179, 182 Cryptocelis, 19, 24 Cryptocephala, 258, 303, 305; vascular system, 252; prostomium, 259; tentacles, 263; eyes, 272; food, 296 Cryptodrilidae, 357, 362, 373, 382 Cryptodrilus, 372, 382 f. Ctenodrilus, 373 Ctenophores, as hosts, 298 Ctenostomata, 470, 477, 479, 480, 518, 532; occurrence, 478; in fresh water, 492; external characters, 480; reproduction, 507; larva, 511; relation to Phylactolaemata, 493, 502 f.; fossil, 521 n. Cucullanus, 136, 142, 163; C. elegans, 143, 161 Cucumaria, as host, 298 Cuénot, on Gephyrea, 416 n. Cuticle, of Nemathelminthes, 125, 165, 175; of Rotifera, etc., 205, 233, 236; of Polyzoa, 470—see also Epidermis Cuvier, on Oligochaeta, 352; on Gephyrea, 411 Cyclatella, 489 Cyclicobdella, 392 Cycloporus, 19, 22, 24 Cyclops, parasites of, 143, 148, 161 Cyclorhagae, 238 Cyclostomata, 477, 479, 506, 517, 518, 525, 531; occurrence, 478; external characters, 480; ovicells, 507; reproduction, 507, 511; larva, 511; fossil, 520, 521 Cydippe, as host, 298 Cylindroecium, 533 Cylindrostoma, 46; British species, 50 Cyphonautes, 509, 510, 512, 520 Cyprina, Malacobdella found on, 119 Cyrtonia, 224 Cyst, of Land-Planarians, 33; of Myzostoma, 342, 343, 344; (capsules), of Aeolosoma, 370, 375 Cystibranchus, 395, 406 Cysticercoid-larva, 83, 85, 88 Cysticercus-larva, 79, 80; list of, 83; C. cellulosae, 79, 80; C. pisiformis, development, 81, 85, 89 Cysticolous, Myzostomaria, 344 Cystoidotaeninae, 91 Cystotaeninae, 91 Dactylogyrus, 73 Dalyell, on habits of Turbellaria, 6, 10, 20; on regeneration in Polychaeta, 283; on tubes of Polychaeta, 287; on Hirudinea, 405 n.; on larvae of Flustra, 466; on Cristatella, 496 Danielssen and Koren, on Gephyrea, 442, 444 Daphnia, Rotifers attached to, 227 Dapidia, 225 Darwin, on Earthworms, 354, 359, 368 Dasybranchus, 331; gill, 268 Dasychone, 338; gills, 261; eyes, 272; regeneration, 283 Dasydetes, 232, 235 Davaine, on Nematoda, 140, 145 Davainea, 91; D. friedbergeri, 84; D. madagascariensis, 80, 84; D. proglottina, life-history, 84 Davenport, on Urnatella, 491 Davis, on Rotifers, 227 Deep-sea, Polychaeta, 300; Polyzoa, 478 Deinodrilus, 351, 384 Delagia, 478 n. Dendrobaena, 382 Dendrocoelum, 30, 35, 39 Dendrostoma, 422, 425, 428 Dendy, on Land Planarians, 33, 34, 38 Denticles, 248, 250, 316, 522 Dero, 352, 377 Derostoma, 44, 50 Desmogaster, 380 Desmoscolecidae, 159 Desmoscolex, 159, 258 Desor, on Nemertine development, 99; Type of, larva, 113 Development, of Polyclads, 28; of Nemertinea, 99, 113; of Nematoda, 135; of Gordius, 171; of Acanthocephala, 179; of Chaetognatha, 189; of Rotifers, 218; of Archiannelida, 243, 245; of Polychaeta, 274 f.; of Oligochaeta, 365; of Leeches, 399; of Gephyrea, 419, 432, 439, 447; of Phoronis, 458; of Polyzoa, 506, 509—see also Life-history and Larva Diachaeta, 366 Diaphragm, of Nereis introvert, 250, 251; of Terebellidae, 304, 327; of Polyzoa, 469, 470, 500, 508 Diaschiza, 225, 226 Diastopora, 518, 531 Dichogaster, 362, 383 Diclidophora, 73 Dicotylus, 32, 35, 36, 42 Dicranotaenia, 91; D. coronula, life-history, 84 Dicyema, 93; vermiform larva of, 92; hosts of, 94 Dicyemennea, 93, 93; hosts of, 94 Dicyemidae, 92 f. Didymogaster, 383 Didymozoon, 73; D. thynni (= Monostomum bipartitum), 71 Didymozoontidae, 73 Digaster, 358, 359, 382 f. Digenea (Digenetic Trematodes), 5, 52, 62, 73; occurrence and habits, 62; life-histories, 63 f., 71 f. Digestive system, of Leptoplana, 11, 12; of Polyclads, 24; of Triclads, 37, 39; of Rhabdocoelida, 42 f.; of Temnocephala, 53, 54; of Polystomum, 57; of Distomum, 62; absence of, in Cestodes, 74; of Nemertinea, 103, 103, 104; of Nematoda, 130; of Gordiidae, 166, 169; of Chaetognatha, 187; of Rotifers, etc., 209, 233, 237; of Archiannelida, 243; of Polychaeta, 249, 269; of Oligochaeta, 358; of Hirudinea, 396; of Gephyrea, 414; of Phoronis, 454; of Polyzoa, 468, 469, 487 Digitibranchus, 353 Diglena, 212, 217, 224, 226 Digonopora, 16 Dimorphism, in Polystomum, 59; sexual, of Trematodes, 70; of Orthonectida, 95; of Dinophilus, 243; of Polychaeta, 276, 279 f.; of Gephyrea, 438 Dinocharididae, 225 Dinocharis, 225 Dinophilus, 242; D. taeniatus, 242; D. gyrociliatus, sexual dimorphism, 243 Dinops, 223 Diopatra, gill, 318 Diphyllinae, 91 Diplax, 225 Diplectanum, 73 Diplobothrium, 73 Diplocardia, 385 Diplodiscus, 73; D. (Amphistomum) subclavatum, life-history, 71 Diplogaster, 154 Diplois, 225 Diplostomum, 73 Diplozoon, 55, 60, 73; life-history, 60, 61; reproductive organs, 60 Diporochaeta, 381 Diporpa, 60, 61 Diporula, 528 Dipylidium, 81, 91; life-history, 83, 88, 89; specific characters, 90 Disc, in Rotifers, 200, 202 f., 202 Discharge, of genital cells; Nemertinea, 116; Archiannelida, 244; Polychaeta, 256, 274, 275 Discobdella, 226 Discocelis, 19, 23 Discodrilidae, 350, 376, 392, 395 Discopus, 201, 222, 226, 227 Dispharagus, 147, 149, 163 Dispinthera, 225 Distemma, 212, 224, 226 Distomatidae, 73 Distomum advena (= D. migrans), life-history, 71; D. appendiculatum, life-history, 71; D. ascidia, life-history, 71; D. atriventre, life-history, 71; D. brachysomum, life-history, 71; D. buskii, 63; D. caudatum, life-history, 71; D. clavigerum, life-history, 72; D. conjunctum, 63; D. crassum, 63; D. cygnoides, life-history, 72; D. cylindraceum, 72; D. dimorphum, 72; D. echinatum, 63; life-history, 72; D. echiuri, 444; D. endolobum, life-history, 72; D. excavatum, 63; D. ferox, 63; D. globiporum, life-history, 72; D. hians, 63; D. hepaticum (liver-fluke), 3, 63, 67 f.,72; D. heterophyes, 63; D. hystrix, life-history, 72; D. japonicum (= D. spathulatum), 63; D. lanceolatum, 63; D. luteum, excretory system of, 62; D. macrostomum, life-history, 64, 65, 72; D. magnum, 68; D. militare, life-history, 72; D. nodulosum, life-history, 72; D. oculi-humani (= D. ophthalmobium), 63; D. ovocaudatum, life-history, 72; D. pulmonale, 63, 70; D. rathouisi, 63, 70; D. retusum, life-history, 72; D. ringeri (= D. pulmonale), 63; D. signatum, life-history, 72; D. sinense, 70; D. spathulatum, 63; D. squamula, life-history, 72; D. trigonocephalum, life-history, 72; D. westermanni (= D. pulmonale), 63 Distyla, 225 Dithyridium, 91 Ditrupa, 301 Diurella, 225, 226 Dochmius, 133, 135, 142, 160, 163; D. cernua, 143; D. duodenalis, 143, 163; D. stenocephala, 143; D. trigonocephala, 143 Dodecaceria, 287, 326, 327 Dog, parasites of, 80 f., 90, 125, 140, 142, 143, 145 Dolichoplana, 37, 42 Domestic animals, Trematodes of, 67, 68, 70, 72; Cestodes of, 81, 89; Nematodes of, 139 f., 163; Acanthocephala of, 184 Domopora, 531, 532 Dorsal ciliated organ, 247, 254, 256 Dorsal pores, 348 Dorylaimus, 131, 157, 160 Dracunculus, 131, 135, 147 Drepanidotaenia, 91; D. anatina, life-history, 84, 85; D. gracilis, D. infundibuliformis, D. setigera, life-history, 84 Drepanophorus, excretory system, 108; British species, 110 Drilophagidae, 224 Drilophagus, 204, 210, 212, 224, 227 Dugès, on Planarians, 6, 10; on Oligochaeta, 368 Dujardin, on Rotifers, 198; on Gastrotricha, 231; on Kinorhyncha, 236 Duplicature, 499, 500 Duthiersia, 91 Dwarf males, of Myzostoma, 344; of Gephyrea, 438 Ear-cockle, 155 Earthworms, 347, 365; senses, 354; food, 359; effect on the soil, 368; distribution, 369 f.; classification, 380 f.; British, 390—see also Oligochaeta Ebrard, on Hirudinea, 393 Echeneibothrium, 91 Echinella, 73 Echinobothrium, 74, 75, 85, 91 Echinococcus, 80, 83 Echinocotyle, 91 Echinoderes, 236 f., 236 Echinorhynchidae, 182 Echinorhynchus acus, 175, 179; E. angustatus, 174, 183; E. clavula, 183; E. haeruca, 176; E. linstowi, 183; E. lutzii, 183; E. moniliformis, 183; E. proteus, 174, 180, 181, 182, 182 Echinosiphon, 424, 429 Echiuroidea, 241 n., 412, 434, 446; anatomy, 434 f.; classification, 440; development, 439; parasites, 444; habits, 442 Echiurus, 336, 411, 435, 440, 441; development, 439 Eckstein, on Rotifers, 198 Eclipidrilus, 380 Economic uses, of Polychaeta, 296, 297 Ectocyst, 469, 470, 523; of Phylactolaemata, 496 f., 503 Ectoderm, of Mesozoa, 93, 95 Ectoparasitic Trematodes, 4, 52, 53 Ectoprocta, 475, 518; structure, 469; lophophore, 476; reproduction, 506 f.; larva, 509, 510, 511; compared with Entoprocta, 488 Effects, of parasites on their hosts, 56, 68, 69, 80, 94, 162 Eggs, of Leptoplana, 10, 16; of Polyclads, 28; of Triclads, 33, 40; of Rhabdocoels, 47, 48; of Termatodes, 52; of ectoparasitic Trematodes, 54, 58, 60, 61; of endoparasitic Trematodes, 63, 69; of Cestodes, 87; of Orthonectidae, 95; of Nemertinea, 116; of Nematoda, 135, 162; of Gordius, 171; of Acanthocephala, 179; of Chaetognatha, 189; of Rotifera, 200, 216 f.; of Gastrotricha, 234; of Nereis, 256; of Polychaeta, 274, 275; of Phyllodocids, 314; of Scoloplos, 321; of Myzostoma, 343; of Polyzoa, 506, 507 Ehrenberg, on Turbellaria, 3, 6; on Rotifers, 198, 220 n., 228; on Gastrotricha, 231; on Polyzoa (Bryozoa), 475 Eichhorn, on Rotifers, 197 Eisen, on Oligochaeta, 380, 390 Eisig, on Capitellidae, 373; on Bonellia, 443 Electra, 481, 518, 523, 530; larva, 509, 510; variation, 516 Elytra, of Polynoids, 265, 292, 294, 298, 299, 309, 310, 311; phosphorescent, 295, 296; as brood-pouch, 275; of Aphroditidae, 266; arrangement of, 309; of Sigalionina, 313 Enantia, 16 n., 19 Enantiidae, 19 Enchelidium, 157 Enchytraeidae, 359, 360, 361, 366, 367, 370, 375 Enchytraeus, host of Gordius, 173 Encotylabe, 73; eggs of E. pagelli, 58 Endocyst, 471 Endoderm, of Mesozoa, 93, 95 Endoparasitic Trematodes, 4, 52, 62 Enopla, 109 Enoplidae, 157 Enoplus, 157, 160 Entalophora, 518, 532 Enteroploea, 224 Enterostoma, 46; British species, 50 Entoprocta, 475, 479, 487 f., 518; lophophore, 476; reproduction, 506; larva, 509, 510 Eosphora, 216, 218, 224 Ephemera, host of Gordius, 172, 173 Ephesia, 321 Epibdella, 55, 73 Epidermis, of Leptoplana, 11, 12; of Polyclads, 20, 25, 29; of Trematodes, 56; of Cestodes, 85; of Nemertinea, 102; of Nematoda, 125; of Acanthocephala, 175; of Nereis, 249; of Oligochaeta, 349; of Leeches, 396; of Gephyrea, 414; of Phoronis, 454—see also Hypodermis Epigamous, phase, of Nereis, 277 n.; worms, 281 Epistome, in Phoronis, 453, 455; in Phylactolaemata, 476, 476, 499; in larva of Loxosoma, 509 Epistomia, 518, 526 Epithetosoma, 444, 445, 449 Epithetosomatoidea, 412, 444 Epitokous, phase, of Nereis, 277 n. Eretmia, 225, 226 Eriographidae, 258, 338 Erpocotyle, 73 Errantia, 258, 285 Eschara, 516 Escharina, 518 Escharoides, 527 Euchlanididae, 225 Euchlanis, 225, 226 Eucratea, 518, 525, 527, 528 Eudrilidae, 359, 360, 380, 385, 403 f. Eudrilus, 354, 385, 403 f. Euichthydina, 235 Eulalia viridis, 314; pigment, 292; colour, 293; eggs, 314 n. Eumenia, 334 Eunice, 318, 319; nephridium, 254; eye, 255; head, 262; parapodium, 264; gill, 265; chaetae, 266, 267; jaws, 270; substance of tube, 290; commensal, 298; E. tibiana, 290 Eunicidae, 258, 318; palps, 260; tentacles, 262; jaws, 270; tube, 285, 290; colour, 291, 292; parasitic, 297; tubes containing Polynoids, 298; Palaeozoic, 302 Eunicites, 301, 302 Euphrosyne, 318; parapodium, 265; chaetae, 267 Eupolia, 113 Eupolyzoa, 461 Eurycercus, shell of, inhabited by Rotifers, 227 n. Eurylepta, 19 Euryleptidae, 19 Eurythoe, 318 Eustrongylus gigas, 142; E. tubifex, 142 Eusyllis, reproduction of, 278 Excretion, as cause of colour, 291 Excretory system, of Leptoplana, 13; of Polyclads, 25; of Triclads, 41; absent in Acoela, 42; of Temnocephala, 54; of Digenea, 62; of Cestodes, 86; of Nemertinea, 108, 108, 120; of Nematodes, 133; of Acanthocephala, 177; of Rotifers, 199, 213; of Gastrotricha, 234; of Kinorhyncha, 237; of Polychaeta, 253; of Polyzoa, 472 f.—see also Nephridium Exogone, 308; attachment of eggs, 275; reproduction, 278 Eyes, of Leptoplana, 8, 15; of Polyclads, 26, 27; development of, 30; of larval Polystomatidae, 59, 60; of Nemertinea, 102, 106; of Nematodes, 128; of Gordius, 166; of Chaetognatha, 188; of Rotifera, 215; of Gastrotricha, 234; of Kinorhyncha, 238; of Polychaeta, 255, 272, 314, 337, 339; of Oligochaeta, 354; of Leeches, 393, 394, 395; of Gephyrea, 417; of Polyzoon larva, 509 Fabricia, 339; eyes, 272; otocyst, 273 Faecal groove, of Sabellids, 337 Fans, of Chaetopterus, 295, 324 Faraday, on asexual reproduction of Planariae, 6, 40 n. Farre, on Polyzoa, 500, 508 Farrella, 500, 518, 533 Fasciola, 67 Fecampia, life-history, 45 Felt, of Aphrodite, 268, 312 Fertilisation, of Nemertinea, 117; of Nematodes, 135; of Gordiidae, 171; of Acanthocephala, 179; of Chaetognatha, 188; of Rotifers, 217 Filaria, 147, 163; F. attenuata, 134; F. cystica, 142; F. denticulata, 125; F. immitis, 148; F. labiata, 163; F. laticaudata, 125; F. loa, 149; F. medinensis, 147, 157, 163; F. sanguinis hominis, 149, 163; F. papillosa, 163 Filariidae, 147 Filigrana, 340; fission in, 281; tubes, 290 Fimbria tenuis, 157 Fischer, on branchiae in Gephyrea, 416 n. Fishes, Trematodes of, 4, 53, 55, 62, 64, 71, 72; Cestodes of, 77, 84, 85; Nemathelminthes of, 142, 143, 149, 163, 173, 182 Fission, in Bipalium, 34; in Planariae, 40; in Trichoplax, 96; in Salinella, 96; in Polychaeta, 278 f., 279, 280, 282, 340; in Oligochaeta, 374, 375, 377; in Phylactolaemata, 496; in embryos, 365, 511 Fissurella, as host, 298 Flabelligera, 334 Flame-cells, in Leptoplana, 13; in Thysanozoon, 25; in Triclads, 41; in Temnocephala, 54; in Polystomatidae and Tristomatidae, 56; in Distomum luteum, 62; in Cestodes, 86; in Nemertinea, 108, 109; in Rotifers, 213; in Urnatella, 491 Fletcherodrilus, 382 Floscularia, 200, 203, 205, 220, 221, 226 Flosculariaceae, 202, 211, 213, 220 Flosculariidae, 201, 203, 205, 220 n., 221, 230 Flukes, 51 Flustra, 465, 466, 467, 472, 473, 477, 515, 518, 526; avicularia, 482 Flustrella, 467, 477, 518, 532; larva, 513 Flustrina, 518 Food, of Turbellaria, 4; of Leptoplana, 10; of Polyclads, 24; of Triclads, 37; of Acoela, 43 f.; of Rhabdocoela, 45; of Trematodes, 4, 52, 62; of Temnocephala, 53; of Cestoda, 5; of Nemertinea, 115; of Nematodes, 131; of Acanthocephala, 177; of Chaetognatha, 190; of Rotifera, 207, 212; of Gastrotricha, 234; of Polychaeta, 296; of Earthworms, 359; of Leeches, 393, 406 f.; of Gephyrea, 422, 443; of Polyzoa, 467 Foot, in Rotifers, 200, 201 Foraminifera, as food of Polychaeta, 296 Forceps, of Eunice, 270 Forcipate, 210, 211 Formula, for Nematoda, 138 Fornix, 481, 517, 525 Fossil, Polychaeta, 301; Polyzoa, 520; Nemertinea, absence of, 119 Fredericella, 476, 494, 502-505, 518, 519; lophophore, 495; statoblast, 502, 503 Frenzel, on Trematoda, 62; on Salinella, 96 Fresh-water, Turbellaria, compared with marine, 46; Nemertinea, 101, 118; Polychaeta, 284; Polyzoa, 492 Friend, on Oligochaeta, 388 n. Frogs, Trematodes of, 55, 58, 62, 71 f.; Nematodes of, 140, 142, 160, 173 Frontal organ, of Nemertinea, 107 Frontal palps, of Eunicidae, 318 f. Frontal ridge, 260 Frullania, inhabited by Rotifers, 227 Fulcrum, in Rotifers, 210 Funicular tissue, 471 Funiculus, 469, 471, 472, 499, 501 Furcularia, 216, 224, 226 Gamble, on Platyhelminthes, 3 f.; on Mesozoa, 92 f. Gammarus, Rotifers attached to, 227 Gapes, cause of, 144 Gardiner, on development of Acoela, 44 n. Gasterostomatidae, 73 Gasterostomum, 73; G. fimbriatum, life-history, 72; G. gracilescens, 72 Gastrocotyle, 73 Gastrodiscus, 73 Gastrothylax, 73 Gastrotricha, 231 f. Gegenbaur, on Nemertine development, 99 Gemellaria, 518, 526 Gemmation, 281; in Syllidae, 278 f., 279, 280 Geobia, 37 Geodesmus, 34, 42 Geographical distribution, of Turbellaria, 32 f.; of Nemertinea, 117; of Chaetognatha, 191, 534; of Gastrotricha, 235; of Polychaeta, 299 f.; of Oligochaeta, 369 f.; of Leeches, 405; of Gephyrea, 426 f., 432, 441 f.; of Phoronis, 460; of Polyzoa, 492 f., 504, 519 Geonemertes, 101; description of G. chalicophora, 117 Geoplana, 33, 38, 42 Geoplanidae, 35, 42 Geoscolicidae, 351, 362, 386 Gephyrea, 411 f.; history, 411; external characters, 412, 420 f., 430 f., 434 f., 444; body-wall, 414, 436; digestive system, 414, 422, 430, 436, 445; vascular system, 415, 421, 436; respiratory system, 416; body-cavity, 416, 437, 445; nervous system, 416, 431, 437, 445; excretory system, 417, 423, 431, 437, 445; reproductive system, 418, 431, 437, 445; development, 419, 439; food, 422, 443; commensalism, 429; affinities, 241 n., 336, 445 f., 512; British, 449 Germarium, of Rotifers, 216 Germ-yolk-gland, 47 Giard, on Oligochaeta, 368 Gid, induced by Coenurus, 82 Gigantorhynchidae, 183 Gigantorhynchus gigas, 174, 177, 184; G. echinodiscus, G. spira, G. taenioides, 184 Gills, of Polychaeta, 252, 265, 268 f.; of Arenicola, 333; of Chlorhaemidae, 334; of Cirratulus, 326; of Euphrosyne, 265, 318; of Eunicidae, 318; of Nereis, 246; of Sabelliformia, 260, 261; development of, 275; of Sabella, 286; colour of, 294; of Sabellaria, 263; of Serpulidae, 261; of Sternaspis, 336; of Sigalionina, 313; of Terebellidae, 329; of Oligochaeta, 352, 353; of Leeches, 395; of Gephyrea, 416 Gizzard, in Rotifers, 199, 210; in Polychaeta, 271, 307; in Oligochaeta, 358; in Polyzoa, 477, 480, 532 f. Glands, on parapodia, 249; of Phyllodocids, 314; oesophageal, 271, 272, 358; tube-forming, 287, 304, 327 Gland shields, 287, 304, 306; of Sabellids, 337; of Terebellids, 327 Glandular papillae, of Polygordius, 244 Glossiphonia (= Clepsine), 393, 396, 399, 404, 407; anatomy, 397, 398, 401; spermatophore, 402 Glossiphoniidae, 406 Glycera, cirrus, 265; habitat, 286; jaws, 270; nephridium, 254; parapodium, 264; prostomium, 259; tentacles, 262; G. capitata, distribution, 299; G. meckelii, 320 Glyceridae, 258, 320; gills, 268; coelomic corpuscles, 253 Glyphidrilus, 386 Gnathobdellae, 396 f., 407 Gnathobdellidae, 407 Gnathosyllis, colour of, 293 Gobio, parasites of, 182, 183 Golfingia, 426, 428, 430 Goniada, 320 Goodrich, on Oligochaeta, 378 Gordiidae, 123, 164 f. Gordiodrilus, 383 f. Gordius, 164 f., 164; G. tolosanus, 165 f., 170 Gosse, on Rotifers, 198, 209 n., 220 Gossea, 232, 235 Goujon, on Trichina, 146 Gourret, on Chaetognatha, 187 Graff, von, on Rhabdocoelida, 44; on Geonemertes, 101, 117 Graffilla, 50; occurrence, 45 Grassi, on Cestoda, 80 n., 89; on Chaetognatha, 190, 193 Grater, of Eunicidae, 270 Greef, on Echiuroidea, 441, 444 Gregarines, in Polychaeta, 299; in Gephyrea, 444 Gregory, on Polyzoa, 519, 520 Grinder, of Eunicidae, 270 Grube, on Oligochaeta, 347, 352; on Hirudinea, 395 Grubea, 308; attachment of eggs, 275 Guanin, in coelomic corpuscles, 253 Guinea-worm, 147 Gunda, 31, 41, 42 Gundidae, 42 Gymnolaemata, 476, 512, 518; lophophore, 476; in fresh water, 492 Gyrator hermaphroditus, 49 Gyrocotyle (= Amphiptyches), 91; G. rugosa, 77; G. urna, 77 Gyrodactylidae, 53, 61, 73 Gyrodactylinae, 73 Gyrodactylus, 55, 61, 73 Haberlandt, on Convoluta, 43 Habits, of Platyhelminthes, 3, 7, 21, 35, 43; of Nemertinea, 114; of Gordiidae, 170 f.; of Chaetognatha, 189; of Rotifers, 206, 226; of Gastrotricha, 232, 234, 235; of Polychaeta, 285; of Oligochaeta, 366; of Gephyrea, 426, 433, 442; of Phoronis, 451 Haemadipsa, 408; eye, 394 Haemal fluid, 252 Haematocleptes, parasitic, 297 Haementeria, 407 Haemerythrin, 416; in Magelona, 252 Haemoglobin, in Nemertinea, 107, 108; in Chaetopoda, 252, 253, 291, 356; in Gephyrea, 437; in Phoronis, 456 Haemopis, 393, 407 Halicryptus, 432, 433; anatomy, 430 Hallez, on Turbellaria, 7, 21, 40 Halosydna, 298 Hamann, on Nematoda, 131, 133, 136 n.; on Acanthocephala, 176, 180 Hamingia, 435 f., 442; males of, 438 Haplobranchus, 339; gills, 261 Haplodiscus, 43, 49 Haplodrili, 241 Hares, parasites of, 141, 145 Harker, on Oligochaeta, 369 Harmer, on Polyzoa, 465 f. Harris, on Rotifera, 197 Hartog, on Rotifera, 197 f.; on Gastrotricha, 231 f.; on Kinorhyncha, 236 f. Haswell, on Temnocephalidae, 53; on Phoronis, 451 Hatschek, on affinities of Polyclads, 28 n.; on nature of Cestodes, 76; on Trochophore, 229; on development of Gephyrea, 419, 447 Head, of Nereis, 246, 248; of Polychaeta, 259 f.; regeneration of, 283; of Tomopteris, 315; of Aphrodite, 260; of Chlorhaemidae, 334; of Eunice, 262; of Nephthys, 262; of Phyllodoce, 262; of Polydora, 261; of Polynoid, 262; of Sabella, 261; of Sabellaria, 263; of Syllid, 262; of Trophonia, 262 Hedruris, 163 Hekaterobranchus, 326 Heliodrilus, 359, 380 Heliopora, containing Polydora, 298 Heller, on human parasites, 139 Hemichordata, 462 Hemilepidia, colour of, 292 Hemistomum, 73 Hemitubifex, 378 Henlea, 369 Hermadion, 299 Hermaphrodite, Nemertinea, 109; Polychaeta, 273 f. Hermellidae, 258, 341 Hermelliformia, 258, 306, 341 Hermione, 312; chaetae, 266, 267 Hermionina, 309, 311 Herpobdellidae, 407 Hertwig, O., on Chaetognatha, 187 n. Hesionidae, 258, 308; segments, 258; head, 263; swim-bladder, 272; genital organs, 274; parasitic, 297 Hesperodrilus, 352 f., 369, 378 f. Hesse, on nervous system of Nematoda, 127 Heterakis, 131, 139 Heterocotylea, 73 Heterodera, 155, 160, 164 Heterogamy, 66 n. Heteronemertini, 113 Heteronereid phase, 276 f.; chaetae, 246, 276; parapodia, 276, 277 Heteronereis, 276, 281—see Heteronereid Heteropora, 520 n. Heterosyllis, 278, 279, 281 Hexacotyle, 73 Hexarthra, 223, 226 Hibernaculum, 501, 502 Hincks, on Polyzoa, 475, 500, 508, 516, 519, 523 Hippothoa, 528 Hippuraria, 533 Hirudinea, 241, 392 f.; external characters, 392; British species, 393; eyes, 395; branchiae, 395; alimentary canal, 396; vascular system, 396; body-cavity, 397; nephridia, 399; reproductive organs, 401; cocoons, 404; classification, 405 Hirudiniculture, 393 Hirudo, 393, 396 f., 399, 403, 405, 407; nephridium, 400 Hislopia, 492 Histioderma, 302 Histriobdella, 242 n. Histriodrilus, 242 n. Holloway, on Rotifers, 227 Holomyarii, 137 Holostomatidae, 63, 64, 73 Holostomum, 73; H. excavatum, 63 Holothurian, as host, 298 Homalogaster, 73 Hood, of Sabellaria, 263, 306 Hooks, of Trematodes, 53, 56, 57; of Cestodes, 75, 85; of Cestode-larvae, 87, 88; taxonomic value in Cestodes, 90 f. Hoplonemertea, 106, 109, 110; auditory organs, 106, 110; British species, 110; characters, 110; development, 113; proboscis, 110 Hornera, 518, 532 Horse, parasites of, 68, 83, 90, 125, 140, 142, 163 Horse-leeches, 393 f. Horst, on Oligochaeta, 354 Hubrecht on Nemertinea, affinities, 120; classification, 109; excretory system, 108; nervous system, 105 Hudson, on Rotifera, 197, 198, 215 n., 220 n., 223 n., 228 Hudsonella, 224 Huxley, on Rotifers, 198, 229; on Polychaeta, 246; on Molluscoidea, 475 Huxleya, 525, 527 Hyalinoecia, 299, 318, 319; tentacles, 262; composition of tube of, 290 Hydatina, 199, 200, 202, 204, 213, 224, 226, 228 Hydatinidae, 224 Hymenolepis, 91; generic characters, 91; H. diminuta (= Taenia flavopunctata), life-history, 83; specific characters, 91; H. murina (= Taenia murina), 70; life-history, 83, 89, 91; H. nana, 80; life-history, 83; specific characters, 91 Hyocrinus, as host, 342 Hyperiodrilus, 363 f.; reproductive organs, 363 Hypodermic impregnation, 27, 218 Hypodermis (= Epidermis) of Gordius, 165; of Rotifera, etc., 205, 232 Hypophorella, 478, 518, 533; larva, 510 Hyporhynchus, 49 Hystrichis, 147, 149, 163 Ichthydium, 235 Ichthyobdellidae, 406 Ichthyonema, 131, 147, 149, 163 Ichthyotaenia, 91 Ichthyotaeninae, 85, 91 Idmonea, 518, 532 Iguana, parasites of, 142 Iijima, on yolk-glands, 38 n. Illoricata, 223 Ilyodrilus, 378; chaeta, 350 Ilyogenia, 388 Imogine, 19 Inarticulata, 517, 518 Incudate, 210, 211 Incus, in Rotifers, 210 Inermia, 445 Infusoriform embryos, 93 Insects, parasites of, 142, 150, 152, 153, 154, 160, 163, 179, 183, 184, 185 Internal sac, 509, 511 Internode, 525 Interproglottidal glands, 90 Intertentacular organ, 469, 473, 508 Introvert, in Polychaeta, 249, 250; in Gephyrea, 412, 424 Investing membrane, in ectoparasitic Trematodes, 57; in Cestodes, 85 Ioda, form of head, 278 Isacis, 163 Jammes, on skin of Nematoda, 126 Jaws, of Nereis, 248, 250, 270; of Polychaeta, 269 f.; of Eunicidae, 270; of Polynoid, 270; of Autolytus, 270; fossil, 302; of Glycera, 270 Jelly, Miss, on Polyzoa, 523 Jensenia, 50 Jimenez, on Leeches, 407 Joblot, on Rotifers, 197 Johnston, on Hirudinea, 393 Joliet, on development of Rotifers, 218; on Polyzoa, 508 Jungermanniaceae, inhabited by Rotifers, 227 Jurassic, Serpulids, 301; Polyzoa, 520 f. Kaiser, on Acanthocephala, 177 Kamptoderm, 469, 470 Keferstein, on Polycladida, 7, 10 Kennel, von, on Nemertinea, 108; on Malacobdella, 101 n., 119 Kerria, 384 Kinorhyncha, 236 f. Kleinenberg, on Trochophore, 229 Koellikeria, 73 Kölliker, on Distomum okenii, 71 Koren and Danielssen, on Gephyrea, 442, 443 Kowalevsky, on Hirudinea, 397; on Phoronis, 458 Kraepelin, on Polyzoa, 493, 502 Krause, on parasites, 163 Krohn, on Nemertine development, 99 Krohnia, 186; species, 192, 194; American species, 534 Krukenberg, on haemerythrin, 416 Kynotus, 386 Labrorostratus, 297 Lacinularia, 200, 213, 215, 221, 226 Lacrymaria, 235 Laetmonice, 312 Lagenipora, 528 Lamarck, on Gephyrea, 411 Land, Planarians, 4, 30, 33, 34, 36; Nemertines, 101, 117; Oligochaeta, 347 f.; Leeches, 408 Lang, on Polyclads, 7, 17, 21 f., 27, 28 n.; on nature of Cestodes, 76 Lanice, 328; Hypophorella in tubes of, 478, 533 Lankester, on Trochosphere, 229; on Earthworms, 347; on Hirudinea, 397; on Gephyrea, 430, 437, 439; on Podaxonia, 461 Larva, Müller's, 29; of Polystomum, 59; of Diplozoon, 60; of Gyrodactylus, 61; of Holostomatidae, 63, 64; of Distomum 64, 65, 67; hosts of larvae of digenetic Trematodes, 71 f.; of Calliobothrium, 77; of Cestodes, 79 f.; table of Cestode larvae, 83, 85, 87; of Schistocephalus, 84; of Bothriocephalus, 87; of Dipylidium (Cysticercoid), 83, 88 f.; of Mesozoa, 92, 93; of Nemertinea, 113; Trochosphere, 229, 274, 439, 510; of Polygordius, 245; of Polychaeta, 274, 275; of Chaetopterus, 325; of Myzostoma, 344; of Gephyrea, 419, 439; of Phoronis, 458; of Polyzoa, 466, 509, 511, 520 Lateral organs, of Capitellidae, 343—see also Ciliated pits Laurer's Canal (= Laurer-Stieda canal), 57, 87 Leaena, 300, 327 n. Lecanocephalus, 131, 133 Leckenby, on Priapulus, 433 Leeches, 241, 392 f.—see also Hirudinea Leeuwenhoek, on Rotifera, 197 Legrain, on Nematodes in deserts, 156 Legros, on Trichina, 146 Lehnert, on Bipalium, 36, 37 Leidy, on Rotifers, 198 Leimacopsis, 37, 42 Lemnisci, 176 Lepas, as host, 298 Lepidasthenia, 293, 311 Lepidoderma, 235 Lepidonotus (subgenus of Polynoe), eye, 255 Lepralia, 516, 518, 528, 530, 531 n.; L. foliacea, 478, 527; larva, 511 Leprea, 328 Leptodera, 129, 131, 133, 160 Leptoplana, 7, 8, 9, 11, 14, 17; British species, 19; habits, 8 f.; anatomy, 11 f. Leptoplanidae, 19 Leptostoma, 396 Lesson, on Polyclads, 24 Leuciscus, parasites of, 173, 182 Leuckart, on Platyhelminthes, 6, 64 f., 70, 76; on Nemertinea, 99; on Nematoda, 136, 139, 140, 142, 146, 163; on Hirudinea, 395 Leucochloridium, 65, 66 Leucocytes, of Polychaeta, 252 Leucodore—see Polydora Leydig, on Rotifers, 198 Lias, Serpulids in, 301 Libyodrilus, 364, 385, 386 Lichenopora, 518, 531 Life-history, of Trematodes, 4; of Polystomatidae (Polystomum, Diplozoon, Gyrodactylus), 58 f.; of digenetic Trematodes, 63 f.; table of, 71; of Cestodes, 5 f., 87; table of life-histories of Cestodes, 83; of Dipylidium, 88; of Dicyemidae, 93; of Nematoda, 159; of Gordius, 170; of Acanthocephala, 179—see also Development Ligula, 91; occurrence, 85 Ligulinae, 91 Lim Boon Keng, on Earthworms, 349 Lima, nests of, 298 Lime, secreted by Serpulidae, 290 Limnaea truncatula, host of larvae of Distomum hepaticum, 67, 72 Limnatis, 407 Limnias, 205, 221; early description of, 197 Limnodrilus, 378 Lineus, 111; L. marinus (= L. longissimus), 99, 100, 111, 114; Borlase on, 99; size of, 100; L. gesserensis (= L. obscurus = L. sanguineus), recuperative powers of, 116 Linguatulida, affinities of, 344 Linnaeus, on Cestodes, 78; on Gephyrea, 411; on Polyzoa, 474 Linstow, von, on classification of Nematodes, 137; on life-history of Ascaris lumbricoides, 140; on parasitism, 162; on Gordius, 166, 171, 173 Lip, lip-membrane, lip-processes, of Sabellidae, 261, 337 Lipobranchius, 334; shape of body, 259 Lipochromes, in Polychaeta, 292 Lister, on Polyzoa, 497 Lithodomous, Polychaeta, 287 Lithographic slate, fossil Polychaeta from, 301, 302 Liver, -fluke, 51; -rot, 68 Locomotion, of Planarians, 9, 10, 36; of Polyclads, 22 f.; of Nemertinea, 114, 115; of Chaetognatha, 190; of Rotifers, etc., 206, 235; of Dinophilus, 243; of Phylactolaemata, 496 Looss, on Trematoda, 62 n., 66, 70 Lopadorhynchina, 314 Lopadorhynchus, 314; L. erythrophyllum, colour of, 292 Lophochaeta, 351; chaeta, 350 Lophohelia, with Eunice, 298, 319 Lophophore, in Phoronis, 453; in Polyzoa, 476, 476, 495 Lophopus, 494, 499, 504, 505, 518, 519; movements, 496, 497; fission, 496, 506; statoblast, 502, 503 Lorica, in Rotifers, 205 Loricata, 205, 224 Lota, parasites of, 182 Loxosoma, 489 f., 489, 490, 506, 518; on Polychaeta, 299, 489; on other animals, 489; buds, 489, 490, 506; larva, 509 Lug-worm, castings of, 285; as bait, 297 Lumbricaria, 302 Lumbricidae, 362, 371 f., 388 Lumbricobdella, 392 Lumbriconereis, 318, 320; from fresh water, 284 Lumbriconereites (misprinted in text), 302 Lumbriculidae, 350, 361, 379 Lumbriculus, 379; as host of Rotifer, 211 n. Lumbricus, 349, 351, 356, 367, 368, 371, 389 f., 403 f.; generative organs, 362; cocoon, 365 Lunulites, 518; vibracula, 487 Lurg, 317 Lycoridae, 315 Lysidice, 297, 320 MacGillivray, on Polyzoa, 519 M‘Intosh, on Nemertinea, 110 n., 115, 116; on Phoronis, 454 Macraspis, 73 Macrobdella, 393, 406; sense-body, 394 Macrorhynchus, 44, 47; British species, 49 Macrostoma, 44, 47; British species, 49 Macrostomatidae, 49 Magelona, 325; haemerythrin in, 252 Magelonidae, 258, 325 Main-gut, of Leptoplana, 8, 13; of Polyclads, 17 Malacobdella, 101; description of, 119; M. grossa, 110, 119; excretory system of, 108 Malacocotylea (= Digenea), 73 Maldanidae (= Clymenidae), 258, 332; shields, 259; anal funnel, 259; chaetae, 266, 267, 268; colour, 293 Male, of Rotifers, 199, 200, 217, 223 n.; of Echiuroids, 438 Malleate, 210 Malleoramate, 210, 211 Malleus, 210 Mammals, Trematodes of, 62, 63, 67-70, 71 f.; Cestodes of, 77-84, 89-91; Nematodes of, 163; Acanthocephala of, 183, 184 Man, Trematode-parasites of, 63, 68-70; Cestodes of, 74, 78-81, 83, 89 f.; Nematodes of, 125, 139, 140, 143, 145, 147, 163; Gordius of, 173; Echinorhynchus of, 183 Man, De, on free-living Nematodes, 157 Manayunkia, 284, 339 n. Mandible, of avicularium, 482, 524 Manson, on Filaria, 149 Manubrium, 210 Marginal groove, of Leptoplana, 15 Maricola, 30, 32, 42 Marine, Rotifers, 226; Oligochaeta, 366; Leeches, 406 Marphysa, 276, 319; as bait, 297; as host, 297 Mastax, of Rotifers, 199, 210 Masterman, on Chaetognatha, 190; on Phoronis, 461 Mastigocerca, 225 Mastigophora, 518, 529; vibraculum, 484 Mastobranchus, gill of, 268, 331 Matzdorf, on Leeches, 369 Maupas, on Rotifers, 217 Mbalolo, 297 Meckelia asulcata, 111 Mecynostoma, 49 Median pore, in Cheilostomata, 484, 524 Megadrili, 373, 374, 380 f. Megalotrocha, 221 Megapora, 530 Megascolex, 351, 372, 381, 383 Megascolides, 349, 358, 372, 382; body-wall and nephridia, 357 Mégnin, on parasites, 164 Meissner, on Polyzoa, 493 Melania, Coabangia in shell of, 284 Melanin, 292 Melicerta, 202, 205, 206, 210, 215, 218, 219, 221, 226; early description of, 197 Melicertaceae, 203, 221 Melicertidae, 201, 203, 205, 211, 213, 221 Melinna, 330 Membranipora, 481, 492, 518, 519, 523, 528, 530; phosphorescence, 478; function of aperture, 500; larva, 509, 510; variation, 516 Membraniporella, 518, 524, 528 Menipea, 518, 526, 527 Mermis, 131, 150, 160, 163 Mermithidae, 150, 163 Meromyarii, 129, 137, 142 Mertens, on Polyclads, 6, 23 Mesobdella, 407 Mesocestoides, 91; M. lineatus, life-history, 84; specific characters, 90 Mesonemertini, 112 Mesostoma, 44, 45; reproduction, 48; British species, 49 Mesostomatidae, 49 Mesotrochal larva, 325 Mesozoa, 92 f. Metamerism, 249 Metamorphosis, in Polycladida, 16, 28; in Trematodes, 5, 66 f.; in Cestodes, 5, 74, 76, 87-89; in Phoronis, 459; in Polyzoa, 512 Metanemertini, 112 Metastatica (= Holostomatidae), 73; life-histories, 64 Metopidia, 200, 225 Metschnikoff, on Orthonectida, 94; on Nemertines, 99; on Chaetosomatidae, 158 Meyer, on Polychaeta, 261 Michaelsen, on Earthworms, 349, 353, 359, 370 f., 375, 385 Microchaeta, 362 Microcodides, 224 Microcodon, 202, 215, 224, 230 Microcodonidae, 202, 220 n., 224 Microcotyle, 73; eggs of M. labracis, 58 Microcotylinae, 73 Microdrili, 373, 374 f. Microplana, 34, 42 Micropora, 518, 530; zooecium, 523 Microporella, 516, 518, 519, 529; avicularia, 484, 485; median pore, 501 Microscolex, 372, 382, 383, 384 Microstoma, 44; asexual reproduction, 44; sexual organs, 47; British species, 49 Microstomatidae, 49 Micrura, 101, 114; British species, 111 Migrations, of Trematode-larvae, 5, 52, 63 f.; of Cestode-larvae, 5, 74, 83, 87 Millson, on Oligochaeta, 368, 387 Millsonia, 382 f. Milne-Edwards, on Polyzoa, 475 Mimicry, in Polychaeta, 293 f. Mimosella, 518, 532; movement of zooecia, 481 Molluscoidea, 475 Molops, host of Gordius, 172 Monhystera, 160 Moniez, on Cestodes, 84 n., 85; on Earthworms, 369 Moniezia, 83, 91; characters of genus, 90; M. alba, M. benedeni, M. denticulata, 90; M. expansa, 83, 90; M. neumani, M. oblongiceps, M. planissima, M. trigonophora, 90 Moniligaster, 359, 380, 402 Moniligastridae, 361, 373, 380 Monkey, parasites of, 145 Monocotyle, 73 Monocotylinae, 73 Monogenea (Monogenetic Trematodes), 5, 53; classification, 73 Mononchus, 154 Monoophorum striatum, 50 Monopora vivipara, 117 Monoporus rubropunctatus, 49; reproductive organs of, 47 Monostomatidae, 73 Monostomum, 71, 73; life-history, 72 Monostyla, 225, 226 Monotidae, 50 Monotus, 36; British species, 50; M. fuscus, 45; habits, 46 Monozoa, 91 Montgomery, on Stichostemma eilhardii, 118 Monura, 225 Morren, on Earthworms, 347 Moseley, on Land Planarians, 7, 35 n., 37; on Pelagonemertes, 101, 114 Movements, in Rotifers, etc., 206, 235 Moxon, on Rotifers, 198 Mucro, 522, 525 Mucronella, 518, 522, 528, 529, 530, 531 Müller, F., on Triclads, 37; on Polyzoa, 493 Müller, O. F., on Turbellaria, 6; on Rotifers, 197; on Oligochaeta, 348, 352 Müller's larva, 16, 28, 29 Muscles, of Leptoplana, 12; of intestine in Polyclads, 24; of Nemertinea, 102, 103; of Nematoda, 128; of Gordiidae, 165; of Chaetognatha, 187; of Rotifers, etc., 206, 233, 237; of Nereis, 247, 249 f.; of Polyzoa, 469, 470, 472, 499, 500—see also Body-wall Musculo-glandular organ, in Triclads, 39, 40 Myrianida, 280, 308; gemmiparity, 279, 280; markings, 293 Myrianites, 302 Mytilia, 225, 226 Myxicola, 338; tori uncinigeri, 268; eyes, 272; otocyst, 273; tube, 285; supposed mimicry, 294 Myzostoma, anatomy, 342 f.; M. cirriferum, 343; M. glabrum, 342 Myzostomaria, 241; structure and affinities, 342 f. Myzostomatidae, 342 Naidomorpha (= Naididae and Naids), 348, 352, 375 f., 377, 378, 400; chaetae, 350, 367; reproductive organs, 361; asexual reproduction, 281, 377 Nais, 348, 377; chaetae, 350 Nannodrilus, 382 f. Natatory chaetae, of Nereidae, 277; of Syllidae, 278, 307 Nathusius, on parasites, 63, 163 Nauphanta, 314, 315 Nebalia, Rotifers parasitic on, 225 Nectochaeta, 291 Nectonema agile, 164, 168, 169, 173 Nemathelminthes, 123 f., 168 Nematobothrium, 4, 55, 71, 73 Nematoda, 123; anatomy, 124 f.; embryology, 135; classification, 136; life-history of, 159 f. Nematogen, 94; Secondary Nematogen, 94 Nematomorpha, 123, 164 f. Nematoxys, 139, 142, 161, 163 Nematozoa, 137 Nemertes, British species, 110; deposition of ova and spermatozoa in, 116 Nemertinea, affinities, 119; anatomy, 102; body-wall, 102; breeding, 116; cephalic slits and cerebral organs, 107, 273; circulatory system, 106, 107; classification, 109 f.; colour, 102; contractility, 102; development, 113; diagram, 104; digestive system, 103; excretory system, 108, 108; external characters, 101; food, 115; fresh-water forms, 101, 118; generative organs, 109; geographical distribution, 117; habitat, 100; habits, 114; land forms, 101, 117; locomotion, 114, 115; nervous system, 105, 106; parasitic forms, 101, 119; pelagic forms, 101, 114; proboscis, 100, 101 f., 103, 104, 110, 115; regeneration, 115; sense organs, 101, 106, 107; size, 100 Nemertodrilus, 360 Nemertoscolex, 444 Neodrilus, 384 Neorhynchidae, 184 Neorhynchus clavaeceps, 178, 181, 184; N. agilis, 184 Nephelis, 392 f., 397, 399, 401, 403, 405 Nephridium, of Archiannelida, 243, 244; of Nereis, 253; of Arenicola, 253, 254; of Polychaeta, 253; dimorphism of, in Polychaeta, 269; thoracic, of Sabelliformia, 306; of Terebellidae, 327; of Chlorhaemidae, 334; of Myzostoma, 344; of Oligochaeta, 356 f., 381 f., 400; of Leeches, 399; of Gephyrea—see Brown tubes; of Phoronis, 456 Nephthydidae, 258, 317 Nephthys, 317; nephridium, 254; prostomium, 259, 260; head, 262; tentacles, 262; peristomium, 263; parapodium, 264, 265; cirrus, 265; gill, 268; jaws, 270; habitat, 286; as bait, 297 Nereidae, 258, 315; palps, 260; colour, 292 Nereidiformia, 258, 303; vascular system, 252; anal cirri, 259; prostomium, 259, 260; tentacles, 262; peristomial cirri, 263; parapodium, 264 f.; cirri, 265; chaetae, 266; jaws, 269; eyes, 272; ciliated organ, 273; regeneration in, 283; food, 296; fossil, 301 f. Nereilepas, 317 Nereis, 246, 299, 301, 316 f.; anatomy, 245 f., 247 f.; transverse section, 247; parapodium, 246, 247, 265, 317; chaetae, 246; head, 246, 248, 316; alimentary canal, 249 f., 251; jaws, 248, 250, 270, 316; nervous system, 254, 255; eye, 255; vascular system, 247, 251; dorsal ciliated organ, 247, 254, 256; nephridium, 253; reproduction, 256; sexually mature, 276, 276 f.; sexual dimorphism and Heteroneid phase, 276 f.; epitokous (= epigamous) and atokous phase, 277 n.; from fresh water, 284; burrow, 286; pigment, 292; as bait, 297; commensalism, 298; as host, 299; British species, 316 f. Nereites, 302 Nerine, 299, 322; habitat, 286; N. vulgaris, head, 322 Nerve plexus of Nemertinea, 103, 105 Nervous system, of Leptoplana, 13, 14; of Polyclads, 26, 30; of Planaria lactea, 39; reduced in parasitic Rhabdocoels, 45; of Temnocephala, 54; of Polystomatidae, 56; of Cestodes, 75, 86; of Nemertinea, 105, 106; of Nematoda, 127; of Gordiidae, 166; of Acanthocephala, 177; of Chaetognatha, 187; of Rotifera, etc., 215, 234, 237; of Archiannelida, 243, 244; of Polychaeta, 254; visceral, of Polychaeta, 255; of Oligochaeta, 353, 374; of Gephyrea, 416, 431, 437, 440, 445; of Phoronis, 456; of Polyzoa, 471 Neumann, on parasites, 164 Neuropodium, 246, 247, 264, 266, 268 Newton, on zoo-geographical regions, 372 Nicolea, 328; gill, 329 Nicomache, 332; tail, 332; tube, 287; N. lumbricalis, colour, 292; distribution, 299 Nitsche, on Polyzoa, 475 n., 478, 500 Nitzschia, 56, 73 Norman, on Polyzoa, 475 Norodonia, 492 Notamia, 518, 526 Noteus, 225 Notholca, 225, 226 Notocotyle, 73 Notomastus, 331; chaetae, 268 Notommata, 217, 224, 226 Notommatidae, 200, 205, 207, 215, 223, 224 Notophyllum, colour, 293 Notopodium, 246, 247, 264, 265, 268 Notops, 200, 224 Notopygos, 259 Nuchal cirri of Eunicidae, 318; Nuchal organ—see Ciliated pits Ocnerodrilus, 383 Octobothrium, 56, 73 Octochaetus, 358, 384 Octocotylinae, 73 Octotrocha, 221 Odontosyllis, reproduction of, 278; as host, 297. Oecistes, 205, 206, 221 Oenonites, 302 Oesophageal glands, 271, 358 Ogmogaster, 73 Oka, on Hirudinea, 399 f.; on Polyzoa, 500 Olfactory pits, in Polyclads, 26; in Triclads, 36 Oligocelis, 42 Oligochaeta, 241, 347 f.; external characters, 348; body-wall, 349; chaetae, 350, 351; branchiae, 352; nervous system, 353; sense-organs, 354; coelom and vascular system, 355; excretory organs, 356; alimentary canal, 358; reproductive organs, 360; habitat, 365; phosphorescence, 368; distribution, 369; classification, 373; Rotifers parasitic on, 227 Oligocladus, 19, 22 Oligognathus, 297 Ollulanus, 142; O. tricuspis, 144, 161 Omalostoma, 49 Onchnesoma, 422, 423, 426, 430, 447 Onchocotyle, 73 Oncholaimus, 157 Onchosphaera-larva of Cestodes, 87, 88 Onuphin, 290 Onuphis, 290, 318, 319; O. conchylega, tube, 287 Onychochaeta, 388; chaeta, 351 Onyx, 131 Ootype, in Polystomum, 59. Operculum, of Serpulidae, 261, 276, 339; of Spirorbis, as brood-pouch, 261, 276; of Cheilostomata, 466, 477, 481, 482, 522, 524 Opesia, 524 Ophelia, 299, 332; eggs, 275; coelomic corpuscles, 252 Opheliidae, 258, 331; gill, 265; ciliated pits, 272 Ophiodromus, 308; O. flexuosus, parasitic, 297 Ophryotrocha, 310, 320; pelagic, 291; genital organs, 274 Opisthotrema, 73 Opistoma, 50 Orbigny, D', on Polyzoa, 519, 520 Orifice, of zooecium, 466, 469, 470, 524; secondary, 522, 524 Örley, on classification of Nematodes, 137 Orthonectidae, 13, 92, 94 f. Otocyst (and Otolith), of Turbellaria, 26; of Nemertinea, 106, 110; of Polychaeta, 273 Otomesostoma, 46, 49 Otoplana, 50 Oudemans, on Nemertinea, 108 Ovary (and Oviduct), of Leptoplana, 11, 14, 16; of Polyclads, 27; of Planaria, 38, 39; of Rhabdocoelida, 47; of Temnocephala, 54; of Polystomatidae, 57; of Diplozoon, 60; of Gyrodactylus, 61; of Distomum macrostomum, 65; of Calliobothrium, 75; of Archigetes, 76; of Schistocephalus, 86; of Rhopalura, 95; of Myzostoma, 343—see also Reproductive organs Ovicell, in Cheilostomata, 466, 466, 468, 481, 482, 484, 522 f., 525; in Cyclostomata, 479, 480, 521, 525 Oviduct—see Ovary Owenia, 325 Ox, parasites of, 79, 83, 125, 139, 140, 143 Oxysoma, 139, 142 Oxyuris, 129, 131, 135, 139, 141, 160; O. ambigua, 141; O. curvula, 141, 163; O. diesingi, 141, 142; O. vermicularis, 141, 163; O. blattae, O. blatticola, O. hydrophili, O. megatyphlon, O. spirotheca, 142 Paddle worm, 313 Paedogenesis, 151 Pagenstecher, on Nemertinea, 99 Palaemonetes, host of Nectonema, 174 Palaeonemertea, 109, 112; characters, 111; development, 113 Palaeozoic, Serpulidae, 301; Eunicidae, 302; Polyzoa, 520 Paleae, of Sabellaria, 267 Palmicellaria, 527, 528 Palolo viridis, as food, 297 Palps, of Nereis, 248, 255; nerves to, 254; of Polychaeta, 260 f.; development of, in Sabelliformia, 275; of Hermelliformia, 306; of Syllidae, 307 Paludicella, 492, 494, 501, 502, 505, 518 Paludicola, 30, 42 Panthalis, 313 Paragnaths, 248, 250, 316 Parapodium, of Nereis, 246, 247; of Polychaeta, 264 f.; of Heteronereid, 276, 277; muscles of, 247; glands of, 249, 314; of Myzostoma, 342 Paraseison, 212, 225, 226 Parasitic, Turbellaria, 51; Polyclads, 22; Triclads, 32; Rhabdocoela, 45, 51; Nemertinea, 101, 119; Rotifers, 204, 227; Polychaeta, 297; Leeches, 406 Parasitism, effect on the parasite, 161, 177; effects on the host, 162 Parenchyma, in Leptoplana, 11, 12; of Müller's larva, 29; in Triclads, 41; in Acoela, 42; in Cestodes, 85, 86 Parovaria, of Phagocata, 38 n. Parthenogenesis, amongst Rotifers, 200 Pectinaria, 330; body, 259; tube, 285, 287; P. auricoma, tube, 288; P. belgica, 330 Pectinatella, 496, 497, 505, 512, 518; statoblast, 502 Pedalion, 200, 201, 206, 211, 216, 223, 224, 225, 228, 230 Pedalionidae, 223 Pedetes, 224 Pedicellina, 487, 488, 490, 506, 507, 518; larva, 510, 513; budding, 514; on Polychaeta, 299 Pelagic, Nemertinea, 101, 114; Chaetognatha, 189; Rotifera, 226; Polychaeta, 291, 294, 314; larvae of Polychaeta, 300, of Polyzoa, 520 Pelagobia, 314 Pelagonemertes, 101, 114 Pelodera, 129, 131, 133 Pelodrilus, 369, 377 Pelodytes, 134 Penis, of Leptoplana, 14, 15; of Polyclads, 27; of Planaria, 38, 39; of Rhabdocoelida, 47; of Temnocephala, 54; of Calliobothrium, 75; of Schistocephalus (cirrus-sac), 86 Pennant, on Hirudinea, 406 n. Pereyaslawzewa, on Acoela, 44 n. Pergens, on Polyzoa, 500 Perichaeta, 351, 357, 358, 372, 381, 381 f., 388, 394, 403 Perichaetidae, 357, 362, 380 Perienteric, blood-sinus, 252 Perionyx, 381 Perissogaster, 383 Peristome, 481, 482, 522, 524 Peristomial (tentacular) cirri, of Nereis, 248; of Polychaeta, 263; nerves to, 254 Peristomium, of Nereis, 248; of Polychaeta, 263; of Sabellidae, 336 Perrier, on Oligochaeta, 367, 385 Petalostoma, 422, 426, 430, 447 Petromyzon, host of Gordius, 173 Petta, intestine of, 271 Phagocata, 31, 32 Phalacrophorus, 314 Phanerocephala, 258, 303 Pharynx, 4; of Leptoplana, 8, 9, 12, 14; of Polyclads, 17, 24; of Discocelis, 23; development of, in Polyclads, 29, 30; of Triclads, 31, 37, 39; of Temnocephala, 53, 54; of Polystomatidae, 56; of Digenea, 62, 64; of Nereis, 249, 250, 251; of Polychaeta, 269 Phascolion, 423, 425, 428 Phascolosoma, 416, 420, 423, 425, 428, 447; as host of Loxosoma, 489 Philippi, on Hirudinea, 406 Philodina, 208, 222, 227 Philodinidae, 222 Phoronis, 450 f., 451, 452, 453, 455; habits, 451; anatomy, 453 f., 457; development, 458, 458; species, 460; affinities, 461, 512 Phosphorescence (and light-producing organs), in Rotifers, 226; in Polychaeta, 272, 295, 296; in Oligochaeta, 368; in Polyzoa, 478 Photodrilus, 368, 383 Photogen (light-producing organ), of Polyophthalmus, 272; of Tomopteris, 296, 315 Phreodrilus, 369, 379 Phreoryctes, 367, 377 Phreoryctidae, 376 Phylactella, 528, 530 Phylactolaemata, 476, 493 f., 518; lophophore, 476, 495; occurrence, 493; movements, 494, 496 f.; reproduction, 501, 506, 507; larva, 511, 512; distribution, 493, 504; affinities, 512 Phyllacanthinae, 91 Phyllobothrinae, 91 Phyllobothrium, 76 n., 91 Phyllocotyle, 73 Phyllodoce, 313, 314; head, 262, 263: eggs, 275, 314 n.; colours, 291, 292; parapodium, 264; chaeta, 267 Phyllodocidae, 258, 313; parapodial cirri, 266; as food, 297; eggs, 314; colours, 292, 293 Phyllodocites, 302 Phyllonella, 73 Phymosoma, 413, 420, 421, 423 f., 425, 426 Physaloptera, 163 Pig, parasites of, 68, 79, 139, 147, 184 Pigments, of Polychaeta, 291 f.; of Gephyrea, 435 Pike, Trematode of, 62; Cestode of, 81, 84 Pilidium larva, 113, 113, 229, 230 Pionosyllis, 308 Piscicola, 393, 406 Pista, 328; gill of, 329 Pits, ciliated, of Polychaeta, 272, 273 Placostegus, colour, 292; from deep sea, 300 Placunella, 73 Plagiochaeta, 358, 381, 384 Plagiostoma, 46; British species, 50 Plagiostomatidae, 50 Planaria, 30, 31 f., 39; British species, 42 Planarians, 3, 7; Dinophilus, compared with, 242, 243 Planariidae, 42 Planctoplana, 19 Plankton, Rotifers in, 225 Planocera, 18, 19, 20 Planoceridae, 19, 23 Planorbis, host of Gordius, 173 Plants, parasites on, 154, 155, 157, 160 Plasmodium, nature of, in Orthonectids, 94 Plate, on Rotifers, 198, 225 n. Platyaspis, 73 Platycotyle, 73 Platyhelminthes, 3 f.; Nemertinea classed with, 119 Plectanocotyle, 73 Plectus, 160 Pleionogaster, 381 Plerocercoid larva, 84 Plessis, du, on Tetrastemma lacustre, 101 n., 118 Pleurocotyle, 73 Pleurotrocha, 224, 226 Ploesoma, 212, 225 Ploima, 202, 203, 212, 213, 216, 220, 223, 226, 227 Plumatella, 493, 494, 499, 503-505, 518, 519; protrusion of polypides, 499; statoblasts, 499, 502, 503; larva, 512 Podal membrane, of Spionidae, 322 Podaxonia, 461 Polyarthra, 201, 224, 226 Polybostrichus, 280 Polycelis, 30, 31, 40, 42 Polychaeta, 241, 245 f.; classification, 257, 258, 303 f,; head, 248, 259 f.; parapodium, 246, 264 f.; chaetae, 246, 266 f.; coelomic fluid, 252; nervous system, 254; sense-organs, 255, 272; ciliated pits, 272; alimentary canal, with pharynx, 249, 250, 251, 269, 270, 271; oesophageal glands, 271 f.; nephridium, 253, 254, 269, 274; genital duct, 254, 269; genital cells, 256, 273 f.; hermaphrodite, 273; regeneration, 278, 282; habits, 285; carnivorous, 304; distribution, 299; from fresh water, 284; from deep sea, 300; pelagic, 291, 314; boring, 287; tubes, 287; pigments, 291; colours, 291 f.; warning colours, 294; protective devices and mimicry, 293; phosphorescent, 295; food of, 296, 299; as bait, 296, 297; as food for man, 297; commensalism, 297 f.; parasitic, 297 f.; as hosts, 299; extinct, 301, 302; larva, 274, 276, 300; provisional chaetae, 274 Polychoerus, 49; development of, 44 n. Polycirrus, 330; habits of, 285; P. aurantiacus, warning colours, 294; phosphorescence, 295; P. haematodes, coelomic corpuscles, 253 Polycladida (Polyclads), 4 f., 7; classification, 16 f.; development, 28 f.; British species, 19, 20, 22 Polycladus, 42 Polycotyle, 73 Polydora (= Leucodore), 323; frontal ridge, 260; head, 261; special chaetae, 267; with Heliopora, 298; P. ciliata, borings, 287 Polydoridae, 258, 323 Polygordius, 242, 244; development, 245 Polymnia, 328 Polymorphism, of Nereis, 277 Polymyarii, 137, 142 Polynoe 310; segments 258; parapodium, 265; jaws, 270; anus, 259; nephridium, 254; habits, 286; as ectoparasites or commensals, 294, 298, 325; distribution, 299, 300; British species, 299, 310 f.; P. squamata, 309; elytron, 310; P. clava, elytron, 310; P. imbricata, elytron, 311 Polynoina (= Polynoids), 309; head, 262; chaetae, 266, 267; jaw, 270; intestine, 271; eggs, 275; sexual dimorphism, 276 n.; tubes, 285; colours, 291, 292; protective resemblance, 294; phosphorescence, 295, 296; food, 296; parasitic and commensal, 297, 325; elytra, 275, 294, 295, 299, 309 f. Polyodontes, 313 n. Polyophthalmus, 332; segmental eyes, 272, 296; otocyst, 273 Polype à pannache, 496 Polypide, 468, 469, 474, 488, 523; retraction and protrusion, 498 f. Polypide-bud, 468, 472, 487, 496, 499, 501, 510; connected with reproduction, 507 Polypostia, 19; penes, 27 Polystomatidae, 53, 55, 73 Polystomatinae, 73 Polystomum, 55, 57; life-history, 58, 59 Polyzoa, 465 f., 475; external characters, 465 f., 479 f.; anatomy, 468 f., 469; brown bodies, 471 f., 472; history, 474 f.; classification, 475 f., 515, 517 f.; occurrence, 477 f.; avicularia and vibracula, 482; enemies, 486; Entoprocta, 487; fresh water, 492 f.; reproduction, 501, 506; development, 509; affinities, 461, 509, 510; metamorphosis, 512; budding, 514; distribution, 493, 504, 519; palaeontology, 520; terminology, 523; determination of British genera, 505, 521, 525 Pomatoceros, habitat, 300, 340 Pompholyx, 201, 203, 225 Pontobdella, 393, 401, 404, 406 Pontodora, 314 Pontodrilus, 366, 370, 383 Pontoscolex, 350, 366, 387 f.; chaeta, 351 Pore, in Polyzoa, 471, 482, 522, 524; median, 484, 524; dorsal, 348 Porella, 516, 518, 522, 527, 529 Porina, 518, 527, 529 Potamilla, 338 Praeoral lobe (= Prostomium), 245, 439 Predaceous worms, 304 Priapuloidea, 412, 446; anatomy, 430; classification, 432; habits, 433 Priapulus, 430, 431, 432; anatomy, 430 f. Pristina, 377 Proales, 204, 224, 226, 227 Proboscidae, 49; occurrence, 44 Proboscis, of Nemertinea, 100, 101 f., 103 f.; of Hoplonemertea, 104, 110; opening by mouth, 117, 119; severance of, 116; of Acanthocephala, 174 f.; of Rotifers, 203; of Kinorhyncha, 237; of Echiuroidea, 434 Proboscis-pore of Nemertinea, 102, 103 Proboscis-sheath of Nemertinea, 103, 103 f. Procerodes, 42 Procerodidae, 42 Procerus, host of Gordius, 172 Procotylea, 36, 42 Proglottis, 5, 74, 75, 79, 85 Promesostoma, occurrence, 44; British species, 49 Proporidae, 49 Proporus venenosus, 49 Prorhynchidae, 49 Prorhynchus sphyrocephalus, terrestrial habit, 44; P. stagnalis, 49 Prosorhochmus claparedii, 110, 114, 117 Prostate-gland, of Leptoplana, 16; of Polyclads, 30; of Planaria, 39; of Rhabdocoela, 47; of Oligochaeta, 361 Prostheceraeus, 19, 22; spermatophores, 27 Prosthiostomatidae, 19 Prosthiostomum, 17, 18, 19, 24 Prostomial tentacles, 248, 262 Prostomium, 241; of Dinophilus, 243; of Polygordius, 244; of Trochosphere, 245; of Nereis, 248; of Polychaeta, 259; of Glyceridae, 320; of Terebellidae, 327; of Oligochaeta, 348 Protodrilus, 242, 244 Protonemertini, 112 Protula, 341; genital organs, 273, 274; eggs, 275 Prouho, on Polyzoa, 489, 507 f. Provisional chaetae, 274 Provortex, British species, 50 Proxenetes, 44; British species, 49 Pruvot, on Polychaeta, 261 Psamathe, 300, 308 Psammolyce, 313; elytra, 294, 313 Pseudalius, 135, 142, 163 Pseudaxine, 73 Pseudoceridae, 19, 20 Pseudoceros, 19, 20 Pseudocotyle, 73 Pseudorhynchus bifidus, 49 Psygmobranchus, 341 Pterobranchia, 461 Pterodina, 200, 201, 203, 206, 211, 215, 216, 225, 226, 230 Pterodinidae, 201, 225 Pteroessa, 224 Pteronella, 73 Pterostichus niger, infested by Gordius, 170, 170, 172 Pterosyllis, ciliated lappets, 273 n. Pyriform organ, 509, 511 Quatrefages, on Gephyrea, 411, 445 Rabbit, parasites of, 141, 145 Ragworm, 322 Railliet, on Cestodes, 91 Rami, in Rotifers, 210 Rasping plate, of Eunicidae, 270 Rattulidae, 210, 225 Rattulus, 212, 225, 226 Ratzel, on Earthworms, 350 Red Cat, 316 Regeneration of lost parts, in Polyclads, 26; in Triclads, 40; in Cestodes, 77; in Nemertinea, 115; in Polychaeta, 278, 282; in Oligochaeta, 348, 379; in Polyzoa, 471, 488 Repetition of parts, 249 Replacement of species, 300 Reproduction (and Reproductive organs), of Leptoplana, 14 f.; of Polyclads, 26, 30; of Triclads, 31, 38, 39; of Rhabdocoelida, 45, 47 f.; of Temnocephala, 54; of Polystomatidae, 57 f.; of Diplozoon, 60; of Digenea, 65; of Calliobothrium, 75; of Schistocephalus, 86; of Mesozoa, 93 f.; of Nemertinea, 102, 103, 104, 109; of Nematoda, 134; of Nematomorpha, 166, 169; of Acanthocephala, 178; of Chaetognatha, 188; of Rotifera, etc., 216, 234, 238; of Archiannelida, 243 f.; of Polychaeta, 253, 254, 256, 269, 273; of Myzostoma, 343; of Oligochaeta, 360; of Leeches, 401; of Gephyrea, 418, 431, 437; of Phoronis, 457; of Polyzoa, 471, 490, 501, 506—see also Ovary and Asexual reproduction Reptiles, parasites of, 163 Respiration, in Nereis, 252; in Chaetopoda, 272; in Gephyrea, 416 Retepora, 479, 515, 518, 527 Rhabdites (rods), of Leptoplana, 11, 12; in Polyclads, 29; in Triclads, 37; absent in parasitic Rhabdocoela, 45; in Temnocephala, 53, 54 Rhabditiformae, 137 Rhabditis, 154, 160; R. nigrovenosa, 140, 155 Rhabdocoelida, 4, 7, 36, 42 f.; occurrence and habits, 43; parasitic forms, 44; reproduction, 47; classification, 49; British species, 43, 44, 49 Rhabdogaster, 158 Rhabdonema nigrovenosum, 134, 136, 140, 151, 160, 161 Rhabdopleura, 461 f. Rhinodrilus, 348 Rhinopidae, 220 n., 224 Rhinops, 224; male of, 223 n. Rhizopoda, as food for Polychaeta, 296 Rhizota, 220 n. Rhombogen (form of Dicyemid), 93 Rhopalonaria, 521 n. Rhopalophorus, 73 Rhopalura giardii, occurrence and structure, 94, 95; R. intoshii, 94 Rhynchelmis, 365, 376 Rhynchobdellae, 396 f., 405 Rhynchodemidae, 35, 42 Rhynchodemus, 34, 35, 42 Rhynchopora, 531 Rhynchozoon, 529 n., 531 Riches, on British Nemertinea, 110; on Malacobdella, 119 Rietsch, on Gephyrea, 443 Rockworm, 319 Rods—see Rhabdites Rohde, on muscles of Nematoda, 128 f. Rootlet, in Polyzoa, 485, 517 Rosa, on Oligochaeta, 364, 380, 385, 390 Rosette-plates, 471, 522 Rotifer, 201, 202, 210, 216, 222, 226, 227 Rotifera, 197 f.; distribution, 200; parasitic, 204; digestive organs, 209; renal organs, 213; nervous system and sense organs, 215; reproduction and development, 216; classification, 220; habits 226; preservation, 228; affinities, 229 Rousselet, on Rotifers, 198, 216, 228 Sabella, 299, 337; parapodium, 265; habitat, 286; tube, 287; tube-building, 288; colour, 293, 294; S. saxicava, habits of, 287 Sabellaria, 341; body, 259; cirri, 265.; tube, 287, 290; S. alveolata, 259, 300; S. spinulosa, paleae, 267, 300 Sabellidae, 258, 336; head, 261; chaetae, 266, 267; regeneration, 283; from fresh water, 284; colour, 292 Sabelliformia, 258, 306, 336; chlorocruorin in, 252; body, 259; head, 260, 261; uncini, 266, 267; nephridia, 269, 306; genital organs, 273; development of gills, 275; gland shields, 287 Saccobdella, 226 Sacconereis, 275, 276, 280 Saccosoma, 434, 440, 442 Sagitella, 321 Sagitta, 186, 186, 191, 534; anatomy, 186 f., 188; development, 189; habits, 190; species, 191, 193; American species, 534 Salensky, on development of Nemertinea, 99; of Rotifers, 218 Salinella, 93, 96 Salivary glands, in Polyclads, 10, 24; in Leeches, 396 Salmacina, 273, 341; brood-pouch, 276; fission, 281 Salpina, 200, 225 Salpinidae, 225 Sandmason, 328 Saxicava, Eulalia in borings of, 314 Scales, of Gastrotricha, 233 Scalibregma, 334 Scalibregmidae, 258, 334 Scapha, 259, 330 Scaridium, 201, 207, 225 Schistocephalus, 75, 91; reproductive organs, 86; larva, 84; life-history, 78, 85 Schizocerca, 225 Schizogamy, in Syllidae, 278, 279, 281 Schizonemertea, 109; characters, 111; development, 113; transverse section, 103 Schizoporella, 518, 527, 528, 529, 530, 531; zooecium and avicularia, 482; Leptoplana on, 22 Schizotheca, 482, 518, 529 Schmarda, on Oligochaeta, 366, 387 Schmidt, on Rhabdocoels, 6 Schneider, on life-history of certain Mesostoma, 48; on classification of Nematoda, 129; on oesophageal glands, 131; on Strongylidae, 142 Schultze, on Polyclads, 13, 26; on Nemertinea, 108, 109 Schultzia, 50 Schulze, F. E., Stichostemma found by, 118; Trichoplax found by, 96 Scirtopoda, 200, 201, 203, 206, 207, 223 Sclerocheilus, 334 Sclerostomum, 163 Scoleciformia, 258, 305, 331 f.; vascular system, 252; buccal region, 269; food of, 296 Scolecolepis, 299, 322 Scolex, 5, 74, 75 f., 89; S. polymorphus, 77; of Taenia solium, 79 Scolithus, 302 Scoloplos, 299, 321; parapodium, 265; habitat, 286 Scruparia, 527 Scrupocellaria, 517, 518, 519, 526; vibracula, 477, 485, 517; phosphorescence, 478; larva, 511 Scutum, 525 Seals, parasites of, 142, 183 Sea-mat, 466, 477 Sea-mouse, 312 Secondary orifice, 522, 524 Sedentaria, 285 Segment, 241; of Nereis, 246, 247 Seison, 226 Seisonaceae, 204, 216, 220 n., 225, 227 Seisonidae, 226 Selenaria, 518; vibracula, 487 Selenka, on Sipunculids, 424 n., 447 Self-fertilisation, in certain Mesostoma, 48; in Trematodes, 52, 58; in Cestodes, 86 Semper, on excretory system of Nemertinea, 108; on Geonemertes palaensis, 101 n., 117; on mimicry in Polychaeta, 294 Sense-organs, of Leptoplana, 13; of Polyclads, 26; of Triclads, 36; of Trematodes, 56, 86; of Cestodes, 86; of Nemertinea, 106; of Nematoda, 128; of Gordius, 166; of Acanthocephala, 178; of Chaetognatha, 188; of Rotifera, etc., 215, 233, 234; of Polychaeta, 255, 272; of Oligochaeta, 354; of Leeches, 395; of Gephyrea, 417; of Phoronis, 457 Septum, of Archiannelida, 244; of Nereis, 249, 251; of Polychaeta, 269; of Chlorhaemidae, 334; of Oligochaeta, 355; of Gephyrea, 440 Serpula, 300, 339, 340; fossil, 301; tubes, 290, 301; commensal with Polynoid, 298; colour, 292 Serpulidae, 258, 339; nerve cords, 255; gills, 261; operculum, 261; cirri, 265; thoracic membrane, 266; uncinus, 267; fission, 281; tube, 290; colour, 292, 293; from great depth, 300; fossil, 301 Serpulite chalk, 301 Seta, of vibraculum, 484, 485, 486, 517, 524 Setosella, 530 Sharks, Trematodes of, 62, 72; Cestodes of, 78 Sheep, parasites of, 67, 81, 82, 83 Sheldon, Miss, on Nemertinea, 99 f. Shell-gland, of Leptoplana, 8, 9, 14, 16; of Polyclads, 28; of Trematodes, 59; of Cestodes, 86 Shield, cuticular, of Polychaeta, 259; of Sternaspis, 335; glandular—see Gland shields. Shipley, on Bipalium, 37; on Nemathelminthes, 123 f.; on Chaetognatha, 186 f., 534; on Gephyrea, 411 f.; on Phoronis, 450 f. Sialis lutaria, host of Gordius, 171, 172; host of Acanthocephala, 185 Side organs, of Carinellidae, 107 Siebold, von, on Tape-worms, 76 Sigalion, 313 Silliman, on Nemertinea, 101, 109, 118 Silurian, Polychaeta, 301 Sinus, in Polyzoa, 482, 484, 525 Siphon, of Capitelliformia, 272, 305; of Gephyrea, 436 Siphonogaster, 353, 368 Siphonostoma, 334; commensal, 298 Sipunculoidea, 412, 420, 446; species, 426 Sipunculus, 425; history, 411; species, 426; anatomy, 412 f., 413, 415; development, 419, 419; food, 422; habits, 426 Size, of Cestodes, 5; of Polyclads, 20; of Land Planarians, 33; of Cestodes, 75; of Nemertinea, 100 Slavina, 377 Sluiter, on Gephyrea, 429, 447 Smitt, on Polyzoa, 516 Smittia, 518, 527, 529; zooecium and avicularium, 482 Snakes, parasites of, 142 Solenopharyngidae, 50 Solenopharynx, 50 Solenophorinae, 91 Solenophorus, 91 Sorocelis, 42 Spadella, 186, 189, 192; anatomy, 186 f.; eggs, 189; habits, 190; species, 192, 194; American species, 534 Spallanzani, on Oligochaeta, 348 Sparganophilus, 366, 386; anatomy, 355. Spatangus, as host, 298 Spencer, on Land-Planarians, 34; on earthworms, 349, 380 Spengel, on Gephyrea, 440 Spermatheca, of Dinophilus, 243; of Oligochaeta, 362, 363, 364 Spermatophores, 27, 402 Spermiducal gland, 361 Sphaerodoridae, 320 Sphaerodorum, 321 Sphaerosyllis, 308 Sphaerularia, 150, 153, 160, 161 Sphyranura, 73; setae in, 56 Spine, of Polyzoa, 481, 523 f., 524 Spinther, 318 Spio, 322 Spionidae, 258, 321; larva, 274, 275 Spioniformia, 258, 304, 321; peristomial cirri, 263; gill, 265; chaetae, 266, 267; eyes, 272; food, 296 Spirographin, 290 Spirographis, 338; substance of tube, 290 Spiroptera, 147, 163; S. reticulata, 149; S. obtusa, 161; S. alata, 163 Spirorbis, 340, 341; operculum, 261, 341; genital organs, 273, 274; brood-pouch, 261, 276; fossil, 301; shell, 341 Spirosperma, 378; chaeta, 350 Spirulaea, 301 Sporocysts, 92; of Distomum macrostomum, 64, 65; of D. hepaticum, 67; hosts of, 71 Staggers, induced by Coenurus, 82 Statoblast, 493, 499, 501 f., 506; sessile, 502; germination, 501, 503, 514; resemblance to ephippian ova, 493 Steenstrup, on Tape-worms, 76 Steganoporella, 530 Stelechopoda, 344 Stelechopus, 342 Stenostoma, 44, 49; asexual reproduction, 44 Stephanoceros, 202, 205, 210, 213, 220, 221 Stephanops, 225 Stercutus, 376 Sternaspidae, 258, 335; nephridia of, 305 Sternaspis, 335, 411, 445; anatomy, 335, 336; shape, 259; shield, 259; head, 264; chaetae, 265; gills, 268; intestine, 271; compared with Gephyrea, 336, 447, 449 Sthenelais, 299, 300, 309, 313 Stichostemma eilhardii, 118 Stilesia, 91; generic characters, 90; S. centripunctata, 91; S. globipunctata, 91 Stock, asexual, of Autolytus, 279; of Myrianida, 281 Stolc, on Oligochaeta, 360 Stolon, 480, 488, 518, 525 Stolonata, 518 n. Stomatopora, 518, 532 Stork, parasites of, 63, 163 Strobila, 75, 76 Strobilation, 76 Strodtmann, on Chaetognatha, 191 Stromatoporoids, 520 Strongylidae, 131, 142 Strongylus, 129, 142, 143, 160, 163; S. filaria, 132; S. tetracanthus, 163 Stuhlmann, on Polyzoa, 493 Stuhlmannia, 359, 386 Stylaria, 348, 377 Stylets of Nemertine proboscis, 104, 110 Stylochoplana, 18, 19, 20 Stylochus, 19; development, 28 Stylostomum, 19, 22 Sub-cuticle, 125, 175 Submalleate, 210, 211 Succinea putris, infested by larvae of Distomum macrostomum, 64, 66 Sucker, of Leptoplana, 8, 16 n.; of Triclads, 35, 36; of Temnocephala, 53, 54; of Monogenea, 53, 56, 57, 60; of Digenea, 62, 64, 65, 69; of Cestodes, 75, 79; of Dinophilus, 243; of Chaetopterus, 324; of Myzostoma, 342; of larva of Polyzoa, 509, 511 Summer-eggs, of Mesostoma, 48; of Rotifera, 216 Sutroa, 376, 380 Swim-bladder, of Syllidae, 272 Swimming, of Leptoplana, 9, 10; of Polyclads, 23; of Rotifers, etc., 206, 235 Syllidae, 258, 306; palps, 260; tentacles, 262; head, 262; parapodium, 264; jaw, 270, 271; alimentary tract, 271; swim-bladder, 272; asexual reproduction, 278 f., 279; regeneration, 278, 283; colours, 293; phosphorescence, 296; ancestral, 303 Syllis, 274, 307; development, 278; S. armillaris, 307; S. ramosa, 282; S. vivipara, 276 Synapta, bearing Rotifers, 222, 227 Synchaeta, 200, 204 f., 224, 226 Synchaetidae, 223, 224 Syncoelidium, 33, 42 Syncytium, 125 Syngamus trachealis, 130, 142, 144, 161, 163, 164 Syrinx, 411 Taenia, 74, 78, 79, 91; life-histories of species of, 83; table of species, 89; T. (Cysticercus) acanthotrias, 80; T. coenurus, 81, 82; life-history, 83; specific characters, 90; T. crassicollis, life-history, 78, 83; specific characters, 89; T. echinococcus, 80; life-history, 83; specific characters, 90; T. krabbei, 81; T. marginata, 81; life-history, 83; specific characters, 90; T. (Hymenolepis) murina, 70, 80 n., 89; life-history, 80, 83; specific characters, 91; T. perfoliata, 163; T. saginata (= T. mediocanellata), 78, 79; life-history, 83; specific characters, 89; T. serialis, 82; life-history, 83; specific characters, 90; T. serrata, 81; life-history, 83, 87, 89; specific characters, 90; T. solium, 79; life-history, 79, 83; specific characters, 89 Taeniasis, 82 Taeniidae, 91 Tail, of Arenicola, 333; of Nereis, 246, 248; regeneration of, 283 Tanypus, host of Gordius, 172 Tape-worms, 5, 74 Taphrocampa, 200, 204, 224 Tardigrada, affinities, 344 Telmatodrilus, 378 Temnocephala, 4, 53, 54, 73 Temnocephalidae, 53, 73; habits and structure, 53 f.; affinities, 54 Tennent, on land-leeches, 408 Tentacles, in Polyclads, 15, 26; in Triclads, 30, 36; in Vorticeros, 45, 46; in Trematodes, 53; (peristomial), of Spionidae, 322; (prostomial), 255, 260, 262 f.; of Nereis, 248; of Polycirrus, 294, 295; of Polygordius, 244; of Terebellids, use of, 289; nerves to, 254 Tentacle-sheath, in Polyzoa, 470 Tentacular cirri = Peristomial cirri, q.v. Tentacular filaments, 304; of Cirratulids, 326, 327 Terebella, 328; otocyst, 273; fossil, 301; T. conchilega, tube, 286, 287, 288; building of tube, 289, 290; gill, 329; T. nebulosa, colour, 292; as host, 311; gill, 329 Terebellidae, 258, 327; shape, 259; tentacles, 263; gill, 265; chaetae, 266, 267; gizzard, 271; tube, 286; use of tentacles, 289; colour, 293; phosphorescence, 296; food of, 296; tube containing Polynoid, 298 Terebellides, 299, 330; gill, 329 Terebelliformia, 258, 325; definition, 304; genital organs, 273; gland shields, 287; nephridia, 269; nuchal organs, 273; uncini, 266, 267; vascular system, 252 Terebripora, 478 Terricola, 30, 42 Tertiary, Polyzoa, 521 Tessin, on Rotifers, 198, 218 Testes, of Leptoplana, 14, 15; of Planaria lactea, 38, 39; of Acoela and Alloeocoela, 47; of Temnocephala, 54; of Polystomum, 57; of Cestodes, 75, 76, 86—see also Reproductive organs Tetragonurus, 389 Tetraonchus, 73 Tetraphyllidae, 91 Tetrarhynchidae, 91 Tetrarhynchus, 75, 76 n., 85, 91 Tetrastemma, British species, 110; land forms, 101, 115, 118; fresh-water forms, 101, 118; excretory system, 108, 109; habits, 114; hermaphrodite species, 109; viviparous species, 117 Thalamoporella, 530 Thalassema, 411, 435 f., 441, 443; development, 439; habits, 443 Thelepus, 299, 329 Theodisca, 321 Thompson, J. V., on term Polyzoa, 475 Thoracic membrane, 266, 305 Thorax, of Polychaeta, 259, 306, 337 Thysanosoma, 91; generic characters, 90; T. fimbriata, life-history, 83; specific characters, 90; T. giardii, specific characters, 90 Thysanozoon, 13, 18, 19, 20 Tomopteridae, 258, 291, 315 Tomopteris, 315; colour, 294; light-producing organ, 296; prostomium, 259; T. rolasi, 315 Tooth, in Polyzoa, 482, 522 Tortoise, Temnocephala associated with, 53 Torus uncinigerus, 268 Tracks, fossil, 302 Travisia, 332 Travisiopsis, 321 Trematoda, 4, 51 f.; life-histories, 71; classification, 73 Trembley, on Turbellaria, 6; on Polyzoa, 496, 497 Trepostomata, 520 Triaenophorus (= Tricuspidaria), 91; excretory system, 84 Triarthra, 201, 203, 206, 211, 224, 225, 226 Triarthridae, 200, 201, 202, 206, 207, 224, 226 Trias, Serpulid in, 301 Trichina, 131, 135, 144, 161; T. spiralis, 146, 163 Trichinosis, 82, 146, 147 Trichocephalus, 131, 135, 136, 144, 160, 163; species of, 145; T. dispar, 145 Trichochaeta, chaeta, 351 Trichoderma, 159 Trichoplax, 93, 95 Trichosoma, 144, 163; species of, 145 Trichotrachelidae, 144 Tricladida, 7, 30 f.; habits, 35 f.; sexual reproduction, 38; asexual reproduction, 40; classification, 42; British species, 31, 32, 34, 42 Tricoma cincta, 157 Tricuspidaria, 91 Trigaster, 359, 384 Trigonoporus, 19, 27 Trinephrus, 357, 382 f. Triophthalmus, 224 Triphylus, 224 Tristicochaeta, 158 Tristomatidae, 53, 55, 73 Tristomatinae, 73 Tristomum, 73 Triticella, 478, 518, 533 Trocheta, 393, 407 Trochophore, 229 Trochopus, 73 Trochosphaera, 200, 201, 221, 229, 230 Trochosphaeridae, 221 Trochosphere, of Archiannelida, 243, 245; of Polychaeta, 274, 275, 510, 512; of Echiuroidea, 439, 510; of Polyzoa, 510 Trochus, in Rotifers, 202, 204 Trophi, of Rotifers, 209, 210 Trophonia, 299, 334; genital organs, 273; head, 262; intestine, 271 Trunk, of Nereis, 246; of Polychaeta, 259; of Gephyrea, 412 f. Tube, of Rotifers, 205; of Polychaeta, 287 f.; composition of, 290; fossil, 301, 302; of Chaetopterus, 323; of Clymene, 287; of Dodecaceria, 326; of Eunice tibiana, 290; of Eunicidae, 285, 290, 318; of Haplobranchus, 339; of Hekaterobranchus, 326; of Hyalinoecia, 290, 319; of Maldanidae, 332; of Myxicola, 285, 338; of Nereis, 316; of Nicomache, 287; of Onuphis, 287, 319; of Owenia, 325; of Pectinaria, 285, 288, 330; of Polydora, 323; of Polynoids, 285; of Panthalis, 313; of Sabella, 287 f.; of Sabellaria, 287; of Sabellidae, 337; of Serpulidae, 290, 339 f., 340; of Terebellidae, 286, 287, 288, 289, 327 f.; of Priapuloidea, 433; of Echiurus, 444 Tube-forming glands, 304 Tube-making, of Polychaeta, 287 f. Tubicolous Polychaeta, 285, 300, 304, 306 Tubifex, 351, 367, 369, 378; chaetae, 350 Tubificidae, 350, 361, 366, 378 Tubulipora, 518, 531, 532 Turbellaria, 3 f. Turtles, parasites of, 142 Tylenchus, 131, 154, 155, 157, 160, 163 Tylosoma, 422, 423, 426, 430, 447 Typhloscolecidae, 258, 291, 321; nuchal organ, 273 n. Typhloscolex, 321 Typosyllis, regeneration of head, 283 n. Udekem, D', on Oligochaeta, 365 Udonella, 73; U. caligorum, 55; U. pollachii, eggs of, 58 Udonellinae, 73 Umbonula, 531 Uncinaria, 143 Uncinate, 210, 211 Uncini, of Polychaeta, 266, 267, 304, 305 Uncus, 210 Urnatella, 490, 493, 518 Urobenus, 388 Uteriporus, 42 Uterus, of Leptoplana, 8, 14; of Planaria, 38, 39; of Triclads, 40; of Rhabdocoela, 48; of Temnocephala, 54; of Polystomum, 57, 59; of Diplozoon, 60; of Didymozoon, 71; of Calliobothrium, 75; of Taenia, 79; of Schistocephalus, 86; in Bothriidae, 87; of Rotifers, 216 Vagina, of Leptoplana, 16; in ectoparasitic Trematodes, 57 f.; in Cestodes, 86, 87 Vaillant, on Hirudinea, 392, 405 Valencinia, 113; V. lineformis, 112 Valkeria, 533 Vallentin, on Rotifers, 198 Vallisnia, 73 Vanadis, 315 Varme, 297 Vasa deferentia, of Leptoplana, 14, 15; of Planaria, 38, 39; of Acoela and Alloeocoela, 47; of Diplozoon, 60; of Schistocephalus, 86 Vasa efferentia, of Leptoplana, 14, 15; of Triclads, 38 Vascular System, of Nemertinea, 106, 107; of Archiannelida, 244; of Nereis, 251 f.; of Polychaeta, 251 f.; of Cryptocephala, 252; of Scoleciformia, 252; of Terebelliformia, 252; absence of, in certain Polychaeta, 253; of Oligochaeta, 355; of Leeches, 396; of Gephyrea, 415, 436, 447; of Phoronis, 455 Vaucheria, Rotifers in, 227 Vejdovsky, on Rhabdocoels, 46; on Gordius, 164, 166; on Oligochaeta, 365, 369, 374, 400 Vermes, 347 Vermiculus, 378 Vermiformia, 461 Verrill, on Chaetognatha, 534 Vertebrates, parasites of, 163, 174, 179, 183 Verworn, on statoblasts, 501 Vesicula seminalis, of Planaria, 39 Vesicularia, 481, 518, 533 Vesicularina, 518, 523 Vestibule, 488, 490; of larva, 509 Vibracular zooecium, 485, 486, 517, 524 Vibraculum, 477, 484, 485, 517, 524; movements, 487; function, 486 Vicarious avicularia, 482 Victorella, 492, 501, 505, 518, 533 Villot, on life-history of Gordius, 172 Vinella, 521 n. Virgate, 210 Visceral nervous system, of Nereis, 255 Vitellarium = Yolk-gland, q.v. Vitello-intestinal canal, in Polystomatidae, 57 Viviparous, Nemertinea, 109, 117; Rotifers, 200, 216 f.; Polychaeta, 256, 276 Volvox, Rotifers in, 227 Vortex, 44; British species, 50; body-cavity, 43 Vorticellids, on Polychaeta, 299 Vorticeros, British species, 45, 46, 50 Vorticidae, 50 Vuillemin (misprinted in text), on Nematodes in deserts, 156 Walford, on Polyzoa, 521 Ward, on Nectonema, 168; on Sipunculus, 417 Warning colours, in Polychaeta, 294, 314 Waters, on Polyzoa, 517 Wheeler, on Myzostomaria, 344 Whelk, shell occupied by Nereis, 298 White Cat, 317 Whitman, on Dicyemidae, 94; on Hirudinea, 395 f., 402, 405 f. Willemoes-Suhm, von, on Tetrastemma agricola, 101, 115, 117, 118 Willey, on affinities of Nemertinea, 120 n.; on Oligochaeta, 382 Wings, of Chaetopterus, 295, 324 Winter-eggs, of Mesostoma, 48; of Rotifers, 217; compared with statoblasts, 493 Woodworth, on yolk-glands, 38 n. Wreath, in Rotifers, 200 Wright, on Phoronis, 450, 456 Yellow-cells, in Leptoplana, 13 Yolk-gland, in Planaria, 38, 39; in Rhabdocoelida, 47; in Temnocephala, 54; in Polystomatidae, 57; in Calliobothrium, 75; in Schistocephalus, 86; in Rotifers, 199, 216 Yoruba Worm, 368, 387 Youatt, on Coenurus, 82 Yungia, 19, 25 Zebra, parasites of, 140 Zelinka, on Rotifers, 198, 215 n., 218, 219, 227, 229; on Gastrotricha, 232 Zooecium, 466, 469, 474, 488, 523; of Phylactolaemata, 495; loss of zooecia, 481, (= calyces), 488; primary, 506; alterations with age, 522 Zone of budding, 279, 283 Zooid, sexual and asexual, 278 f. Zoophytes, 465, 474