of Monogenea,53,56,57,60;of Digenea,62,64,65,69;of Cestodes,75,79;ofDinophilus,243;ofChaetopterus,324;ofMyzostoma,342;of larva of Polyzoa,509,511Summer-eggs, ofMesostoma,48;of Rotifera,216Sutroa,376,380Swim-bladder, of Syllidae,272Swimming, ofLeptoplana,9,10;of Polyclads,23;of Rotifers, etc.,206,235Syllidae,258,306;palps,260;tentacles,262;head,262;parapodium,264;jaw,270,271;alimentary tract,271;swim-bladder,272;asexual reproduction,278f.,279;regeneration,278,283;colours,293;phosphorescence,296;ancestral,303Syllis,274,307;development,278;S. armillaris,307;S. ramosa,282;S. vivipara,276Synapta, bearing Rotifers,222,227Synchaeta,200,204f.,224,226Synchaetidae,223,224Syncoelidium,33,42Syncytium,125Syngamus trachealis,130,142,144,161,163,164Syrinx,411Taenia,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,70,80n.,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,89Taeniasis,82Taeniidae,91Tail, ofArenicola,333;ofNereis,246,248;regeneration of,283Tanypus, host ofGordius,172Tape-worms,5,74Taphrocampa,200,204,224Tardigrada, affinities,344Telmatodrilus,378Temnocephala,4,53,54,73Temnocephalidae,53,73;habits and structure,53f.;affinities,54Tennent, on land-leeches,408Tentacles, in Polyclads,15,26;in Triclads,30,36;inVorticeros,45,46;in Trematodes,53;(peristomial), of Spionidae,322;(prostomial),255,260,262f.;ofNereis,248;ofPolycirrus,294,295;ofPolygordius,244;of Terebellids, use of,289;nerves to,254Tentacle-sheath, in Polyzoa,470Tentacular cirri = Peristomial cirri,q.v.Tentacular filaments,304;of Cirratulids,326,327Terebella,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,329Terebellidae,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,298Terebellides,299,330;gill,329Terebelliformia,258,325;definition,304;genital organs,273;gland shields,287;nephridia,269;nuchal organs,273;uncini,266,267;vascular system,252Terebripora,478Terricola,30,42Tertiary, Polyzoa,521Tessin, on Rotifers,198,218Testes, ofLeptoplana,14,15;ofPlanaria lactea,38,39;of Acoela and Alloeocoela,47;ofTemnocephala,54;ofPolystomum,57;of Cestodes,75,76,86—see also Reproductive organsTetragonurus,389Tetraonchus,73Tetraphyllidae,91Tetrarhynchidae,91Tetrarhynchus,75,76n.,85,91Tetrastemma, British species,110;land forms,101,115,118;fresh-water forms,101,118;excretory system,108,109;habits,114;hermaphrodite species,109;viviparous species,117Thalamoporella,530Thalassema,411,435f.,441,443;development,439;habits,443Thelepus,299,329Theodisca,321Thompson, J. V., on term Polyzoa,475Thoracic membrane,266,305Thorax, of Polychaeta,259,306,337Thysanosoma,91;generic characters,90;T. fimbriata, life-history,83;specific characters,90;T. giardii, specific characters,90Thysanozoon,13,18,19,20Tomopteridae,258,291,315Tomopteris,315;colour,294;light-producing organ,296;prostomium,259;T. rolasi,315Tooth, in Polyzoa,482,522Tortoise,Temnocephalaassociated with,53Torus uncinigerus,268Tracks, fossil,302Travisia,332Travisiopsis,321Trematoda,4,51f.;life-histories,71;classification,73Trembley, on Turbellaria,6;on Polyzoa,496,497Trepostomata,520Triaenophorus(=Tricuspidaria),91;excretory system,84Triarthra,201,203,206,211,224,225,226Triarthridae,200,201,202,206,207,224,226Trias, Serpulid in,301Trichina,131,135,144,161;T. spiralis,146,163Trichinosis,82,146,147Trichocephalus,131,135,136,144,160,163;species of,145;T. dispar,145Trichochaeta, chaeta,351Trichoderma,159Trichoplax,93,95Trichosoma,144,163;species of,145Trichotrachelidae,144Tricladida,7,30f.;habits,35f.;sexual reproduction,38;asexual reproduction,40;classification,42;British species,31,32,34,42Tricoma cincta,157Tricuspidaria,91Trigaster,359,384Trigonoporus,19,27Trinephrus,357,382f.Triophthalmus,224Triphylus,224Tristicochaeta,158Tristomatidae,53,55,73Tristomatinae,73Tristomum,73Triticella,478,518,533Trocheta,393,407Trochophore,229Trochopus,73Trochosphaera,200,201,221,229,230Trochosphaeridae,221Trochosphere, of Archiannelida,243,245;of Polychaeta,274,275,510,512;of Echiuroidea,439,510;of Polyzoa,510Trochus, in Rotifers,202,204Trophi, of Rotifers,209,210Trophonia,299,334;genital organs,273;head,262;intestine,271Trunk, ofNereis,246;of Polychaeta,259;of Gephyrea,412f.Tube, of Rotifers,205;of Polychaeta,287f.; composition of,290;fossil,301,302;of Chaetopterus,323;ofClymene,287;ofDodecaceria,326;ofEunice tibiana,290;of Eunicidae,285,290,318;ofHaplobranchus,339;ofHekaterobranchus,326;ofHyalinoecia,290,319;of Maldanidae,332;ofMyxicola,285,338;ofNereis,316;ofNicomache,287;ofOnuphis,287,319;ofOwenia,325;ofPectinaria,285,288,330;ofPolydora,323;of Polynoids,285;ofPanthalis,313;ofSabella,287f.;ofSabellaria,287;of Sabellidae,337;of Serpulidae,290,339f.,340;of Terebellidae,286,287,288,289,327f.;of Priapuloidea,433;ofEchiurus,444Tube-forming glands,304Tube-making, of Polychaeta,287f.Tubicolous Polychaeta,285,300,304,306Tubifex,351,367,369,378;chaetae,350Tubificidae,350,361,366,378Tubulipora,518,531,532Turbellaria,3f.Turtles, parasites of,142Tylenchus,131,154,155,157,160,163Tylosoma,422,423,426,430,447Typhloscolecidae,258,291,321;nuchal organ,273n.Typhloscolex,321Typosyllis, regeneration of head,283n.Udekem, D', on Oligochaeta,365Udonella,73;U. caligorum,55;U. pollachii, eggs of,58Udonellinae,73Umbonula,531Uncinaria,143Uncinate,210,211Uncini, of Polychaeta,266,267,304,305Uncus,210Urnatella,490,493,518Urobenus,388Uteriporus,42Uterus, ofLeptoplana,8,14;ofPlanaria,38,39;of Triclads,40;of Rhabdocoela,48;ofTemnocephala,54;
of Monogenea,53,56,57,60;
of Digenea,62,64,65,69;
of Cestodes,75,79;
ofDinophilus,243;
ofChaetopterus,324;
ofMyzostoma,342;
of larva of Polyzoa,509,511
Summer-eggs, ofMesostoma,48;
of Rotifera,216
Sutroa,376,380
Swim-bladder, of Syllidae,272
Swimming, ofLeptoplana,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,278f.,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,200,204f.,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,70,80n.,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, ofArenicola,333;
ofNereis,246,248;
regeneration of,283
Tanypus, host ofGordius,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,53f.;
affinities,54
Tennent, on land-leeches,408
Tentacles, in Polyclads,15,26;
in Triclads,30,36;
inVorticeros,45,46;
in Trematodes,53;
(peristomial), of Spionidae,322;
(prostomial),255,260,262f.;
ofNereis,248;
ofPolycirrus,294,295;
ofPolygordius,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, ofLeptoplana,14,15;
ofPlanaria lactea,38,39;
of Acoela and Alloeocoela,47;
ofTemnocephala,54;
ofPolystomum,57;
of Cestodes,75,76,86—see also Reproductive organs
Tetragonurus,389
Tetraonchus,73
Tetraphyllidae,91
Tetrarhynchidae,91
Tetrarhynchus,75,76n.,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,411,435f.,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,Temnocephalaassociated with,53
Torus uncinigerus,268
Tracks, fossil,302
Travisia,332
Travisiopsis,321
Trematoda,4,51f.;
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,7,30f.;
habits,35f.;
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,357,382f.
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, ofNereis,246;
of Polychaeta,259;
of Gephyrea,412f.
Tube, of Rotifers,205;
of Polychaeta,287f.; composition of,290;
fossil,301,302;
of Chaetopterus,323;
ofClymene,287;
ofDodecaceria,326;
ofEunice tibiana,290;
of Eunicidae,285,290,318;
ofHaplobranchus,339;
ofHekaterobranchus,326;
ofHyalinoecia,290,319;
of Maldanidae,332;
ofMyxicola,285,338;
ofNereis,316;
ofNicomache,287;
ofOnuphis,287,319;
ofOwenia,325;
ofPectinaria,285,288,330;
ofPolydora,323;
of Polynoids,285;
ofPanthalis,313;
ofSabella,287f.;
ofSabellaria,287;
of Sabellidae,337;
of Serpulidae,290,339f.,340;
of Terebellidae,286,287,288,289,327f.;
of Priapuloidea,433;
ofEchiurus,444
Tube-forming glands,304
Tube-making, of Polychaeta,287f.
Tubicolous Polychaeta,285,300,304,306
Tubifex,351,367,369,378;
chaetae,350
Tubificidae,350,361,366,378
Tubulipora,518,531,532
Turbellaria,3f.
Turtles, parasites of,142
Tylenchus,131,154,155,157,160,163
Tylosoma,422,423,426,430,447
Typhloscolecidae,258,291,321;
nuchal organ,273n.
Typhloscolex,321
Typosyllis, regeneration of head,283n.
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, ofLeptoplana,8,14;
ofPlanaria,38,39;
of Triclads,40;
of Rhabdocoela,48;
ofTemnocephala,54;