head,261;chaetae,266,267;regeneration,283;from fresh water,284;colour,292Sabelliformia,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,287Saccobdella,226Sacconereis,275,276,280Saccosoma,434,440,442Sagitella,321Sagitta,186,186,191,534;anatomy,186f.,188;development,189;habits,190;species,191,193;American species,534Salensky, on development of Nemertinea,99;of Rotifers,218Salinella,93,96Salivary glands, in Polyclads,10,24;in Leeches,396Salmacina,273,341;brood-pouch,276;fission,281Salpina,200,225Salpinidae,225Sandmason,328Saxicava,Eulaliain borings of,314Scales, of Gastrotricha,233Scalibregma,334Scalibregmidae,258,334Scapha,259,330Scaridium,201,207,225Schistocephalus,75,91;reproductive organs,86;larva,84;life-history,78,85Schizocerca,225Schizogamy, in Syllidae,278,279,281Schizonemertea,109;characters,111;development,113;transverse section,103Schizoporella,518,527,528,529,530,531;zooecium and avicularia,482;Leptoplanaon,22Schizotheca,482,518,529Schmarda, on Oligochaeta,366,387Schmidt, on Rhabdocoels,6Schneider, on life-history of certainMesostoma,48;on classification of Nematoda,129;on oesophageal glands,131;on Strongylidae,142Schultze, on Polyclads,13,26;on Nemertinea,108,109Schultzia,50Schulze, F. E.,Stichostemmafound by,118;Trichoplaxfound by,96Scirtopoda,200,201,203,206,207,223Sclerocheilus,334Sclerostomum,163Scoleciformia,258,305,331f.;vascular system,252;buccal region,269;food of,296Scolecolepis,299,322Scolex,5,74,75f.,89;S. polymorphus,77;ofTaenia solium,79Scolithus,302Scoloplos,299,321;parapodium,265;habitat,286Scruparia,527Scrupocellaria,517,518,519,526;vibracula,477,485,517;phosphorescence,478;larva,511Scutum,525Seals, parasites of,142,183Sea-mat,466,477Sea-mouse,312Secondary orifice,522,524Sedentaria,285Segment,241;ofNereis,246,247Seison,226Seisonaceae,204,216,220n.,225,227Seisonidae,226Selenaria,518;vibracula,487Selenka, on Sipunculids,424n.,447Self-fertilisation, in certainMesostoma,48;in Trematodes,52,58;in Cestodes,86Semper, on excretory system of Nemertinea,108;onGeonemertes palaensis,101n.,117;on mimicry in Polychaeta,294Sense-organs, ofLeptoplana,13;of Polyclads,26;of Triclads,36;of Trematodes,56,86;of Cestodes,86;of Nemertinea,106;of Nematoda,128;ofGordius,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;ofPhoronis,457Septum, of Archiannelida,244;ofNereis,249,251;of Polychaeta,269;of Chlorhaemidae,334;of Oligochaeta,355;of Gephyrea,440Serpula,300,339,340;fossil,301;tubes,290,301;commensal with Polynoid,298;colour,292Serpulidae,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,301Serpulite chalk,301Seta, of vibraculum,484,485,486,517,524Setosella,530Sharks, Trematodes of,62,72;Cestodes of,78Sheep, parasites of,67,81,82,83Sheldon, Miss, on Nemertinea,99f.Shell-gland, ofLeptoplana,8,9,14,16;of Polyclads,28;of Trematodes,59;of Cestodes,86Shield, cuticular, of Polychaeta,259;ofSternaspis,335;glandular—see Gland shields.Shipley, onBipalium,37;on Nemathelminthes,123f.;on Chaetognatha,186f.,534;onGephyrea,411f.;onPhoronis,450f.Sialis lutaria, host ofGordius,171,172;host of Acanthocephala,185Side organs, of Carinellidae,107Siebold, von, on Tape-worms,76Sigalion,313Silliman, on Nemertinea,101,109,118Silurian, Polychaeta,301Sinus, in Polyzoa,482,484,525Siphon, of Capitelliformia,272,305;of Gephyrea,436Siphonogaster,353,368Siphonostoma,334;commensal,298Sipunculoidea,412,420,446;species,426Sipunculus,425;history,411;species,426;anatomy,412f.,413,415;development,419,419;food,422;habits,426Size, of Cestodes,5;of Polyclads,20;of Land Planarians,33;of Cestodes,75;of Nemertinea,100Slavina,377Sluiter, on Gephyrea,429,447Smitt, on Polyzoa,516Smittia,518,527,529;zooecium and avicularium,482Snakes, parasites of,142Solenopharyngidae,50Solenopharynx,50Solenophorinae,91Solenophorus,91Sorocelis,42Spadella,186,189,192;anatomy,186f.;eggs,189;habits,190;species,192,194;American species,534Spallanzani, on Oligochaeta,348Sparganophilus,366,386;anatomy,355.Spatangus, as host,298Spencer, on Land-Planarians,34;on earthworms,349,380Spengel, on Gephyrea,440Spermatheca, ofDinophilus,243;of Oligochaeta,362,363,364Spermatophores,27,402Spermiducal gland,361Sphaerodoridae,320Sphaerodorum,321Sphaerosyllis,308Sphaerularia,150,153,160,161Sphyranura,73;setae in,56Spine, of Polyzoa,481,523f.,524Spinther,318Spio,322Spionidae,258,321;larva,274,275Spioniformia,258,304,321;peristomial cirri,263;gill,265;chaetae,266,267;eyes,272;food,296Spirographin,290Spirographis,338;substance of tube,290Spiroptera,147,163;S. reticulata,149;S. obtusa,161;S. alata,163Spirorbis,340,341;operculum,261,341;genital organs,273,274;brood-pouch,261,276;fossil,301; shell,341Spirosperma,378;chaeta,350Spirulaea,301Sporocysts,92;ofDistomum macrostomum,64,65;ofD. hepaticum,67;hosts of,71Staggers, induced byCoenurus,82Statoblast,493,499,501f.,506;sessile,502;germination,501,503,514;resemblance to ephippian ova,493Steenstrup, on Tape-worms,76Steganoporella,530Stelechopoda,344Stelechopus,342Stenostoma,44,49;asexual reproduction,44Stephanoceros,202,205,210,213,220,221Stephanops,225Stercutus,376Sternaspidae,258,335;nephridia of,305Sternaspis,335,411,445;anatomy,335,336;shape,259;shield,259;head,264;chaetae,265;gills,268;intestine,271;compared with Gephyrea,336,447,449Sthenelais,299,300,309,313Stichostemma eilhardii,118Stilesia,91;generic characters,90;S. centripunctata,91;S. globipunctata,91Stock, asexual, ofAutolytus,279;ofMyrianida,281Stolc, on Oligochaeta,360Stolon,480,488,518,525Stolonata,518n.Stomatopora,518,532Stork, parasites of,63,163Strobila,75,76Strobilation,76Strodtmann, on Chaetognatha,191Stromatoporoids,520Strongylidae,131,142Strongylus,129,142,143,160,163;S. filaria,132;S. tetracanthus,163Stuhlmann, on Polyzoa,493Stuhlmannia,359,386Stylaria,348,377Stylets of Nemertine proboscis,104,110Stylochoplana,18,19,20Stylochus,19;development,28Stylostomum,19,22Sub-cuticle,125,175Submalleate,210,211Succinea putris, infested by larvae ofDistomum macrostomum,64,66Sucker, ofLeptoplana,8,16n.;of Triclads,35,36;ofTemnocephala,53,54;
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,186f.,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,Eulaliain 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;
Leptoplanaon,22
Schizotheca,482,518,529
Schmarda, on Oligochaeta,366,387
Schmidt, on Rhabdocoels,6
Schneider, on life-history of certainMesostoma,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.,Stichostemmafound by,118;
Trichoplaxfound by,96
Scirtopoda,200,201,203,206,207,223
Sclerocheilus,334
Sclerostomum,163
Scoleciformia,258,305,331f.;
vascular system,252;
buccal region,269;
food of,296
Scolecolepis,299,322
Scolex,5,74,75f.,89;
S. polymorphus,77;
ofTaenia 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;
ofNereis,246,247
Seison,226
Seisonaceae,204,216,220n.,225,227
Seisonidae,226
Selenaria,518;
vibracula,487
Selenka, on Sipunculids,424n.,447
Self-fertilisation, in certainMesostoma,48;
in Trematodes,52,58;
in Cestodes,86
Semper, on excretory system of Nemertinea,108;
onGeonemertes palaensis,101n.,117;
on mimicry in Polychaeta,294
Sense-organs, ofLeptoplana,13;
of Polyclads,26;
of Triclads,36;
of Trematodes,56,86;
of Cestodes,86;
of Nemertinea,106;
of Nematoda,128;
ofGordius,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;
ofPhoronis,457
Septum, of Archiannelida,244;
ofNereis,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,99f.
Shell-gland, ofLeptoplana,8,9,14,16;
of Polyclads,28;
of Trematodes,59;
of Cestodes,86
Shield, cuticular, of Polychaeta,259;
ofSternaspis,335;
glandular—see Gland shields.
Shipley, onBipalium,37;
on Nemathelminthes,123f.;
on Chaetognatha,186f.,534;
onGephyrea,411f.;
onPhoronis,450f.
Sialis lutaria, host ofGordius,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,412f.,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,186f.;
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, ofDinophilus,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,481,523f.,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;
ofDistomum macrostomum,64,65;
ofD. hepaticum,67;
hosts of,71
Staggers, induced byCoenurus,82
Statoblast,493,499,501f.,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, ofAutolytus,279;
ofMyrianida,281
Stolc, on Oligochaeta,360
Stolon,480,488,518,525
Stolonata,518n.
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 ofDistomum macrostomum,64,66
Sucker, ofLeptoplana,8,16n.;
of Triclads,35,36;
ofTemnocephala,53,54;