Acanella, as host,298Acanthobdella,395Acanthocephala,123,124,174f.;embryology,179;classification,181Acanthocotyle,73Acanthodrilidae,357,362,381,383,384Acanthodrilus,356,363,366,372,382,384;chaetae,350Acanthozoon,20Accessory gut, of Polychaeta,305Aceros,19Achaeta,445Acholoe,297Aciculum,247; fossil,302Acmostoma,50Acoela,42;occurrence and habits,43;reproduction,47;classification,49Acotylea,16f.,17,18Acrorhynchus,49;occurrence,44Actinotrocha larva,458Actinurus,201,222Acyclus,221Adaptation, of Trematodes,52,62;of Cestodes,74;of Nematodes,161Adherent,523Adineta,204,222,227Adventitious avicularia,482Aeolosoma,349,353,354,360,370,374,375Aetea,518,525Agassiz, on Syllidae,280Alaurina claparedii,49Albertia,204,210,213,224,227Alciope,315Alciopids (Alciopina),314;head,263;parapodium,265;habit,291;light-organs,294Alciopina parasitica,298Alcyonella,494,505,518Alcyonellea,518Alcyonidium,477,480,492,518,532;structure of zooecium,469;reproduction,507,508;larva,510,511Alimentary canal—see Digestive SystemAlitta,317Allantonema,131,150,151,161Allman, on Polyzoa,474,475Alloeocoela,43; habits,46;reproduction,47;classification,50Alloiogenesis,66n.Allolobophora,351,367,369,371,386,389,390f.;cocoons,365Allostoma pallidum,50Alluroides,379Allurus,351,366,370,389;cocoons,365Alma,352f.,387Alternation of generations,66,81,281Amathia,481,518,532Ammocharidae,258,325Ammotrypane,273,331;intestine,271Ampharete,330Ampharetidae,258,330Amphibia, Trematodes of,55,62,71,72;Nematodes of,163Amphichaeta,377Amphicoerus,49Amphicora,339Amphicorine, gill,261Amphicorinidae,258,339Amphicteis,330Amphictenidae,258,330Amphiglena,273,339Amphileptus,235Amphilina,91Amphinome, eye of,255;A. smaragdina, colour,293Amphinomidae,258,318;shape,259;caruncle,260,273n.;head,262,263;parapodium,264;cirri,265;chaetae,267,267;inLepas,297Amphiporus,102,114;British species,110Amphiptyches,77Amphistomatidae,73Amphistomum,71,73;A. hominis,63Amphitrite,327,328;gill,329Ampullaria,Temnocephalawith,53Anachaeta,350,376,395Anal, cirri,259;funnel,259,332,333;vesicles,358,436Anangian worms,253Anarthropora,529Ancylostomum,143,163Andrews, onSipunculus,417,426Angiostomum,134Angler-fish, Trematodes of,62,72Anguillula aceti,125,154;A. tritici,125;A. diplogaster,155Anguillulidae,137,154Anguinella,532Annadrilus,386Annelida,241Anocelis,42Anonymidae,19Anonymus,16,18,19,20;penes,27Anopla,109Anoplocephala,91;characters,90:A. mamillana,90;A. perfoliata, life-history,83;specific characters,90:A. plicata, specific characters,90Anoplodiscus,73Anoplodium,50;A. parasiticum, occurrence,45Antaeus,388Antedon, as host,342Antenna, of Rotifers,215Anthobothrium,76n.,91Anthocotyle,73Antinoë,298Antipathes, as host,298Anuraea,225,226Anuraeidae,201,205,225,226A'oon, an edible worm,297Apel, on Priapuloidea,433Aperture, of zooecium,468,517,523,524Aphaneura,353,374Aphanostoma,49Aphanostomatidae,49Aphelenchus,131,155,157Aphrodite,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,299Aphroditidae,258,309;frontal ridge,260;parapodium,264;elytra,266,309;chaetae,266Apical plate, of Trochosphere,245Apodina,235Apodoides,225Apogon,Scolex polymorphusin,77Apsilidae,201,203,214,220,221Apsilus,201,212,213,214,221Arabellites,302Arachnidium,532Archiannelida,241;anatomy,243f.;nerve cords,255;development,243,245Archigetes,5,74,76,91;significance of,77Area, of zooecium,523,524Arenicola,333;perienteric sinus,252;nephridium,253,254,269;prostomium,259;body,259;head,264;gill,265;chaetae,266f.;genital organs,273;otocyst,273;burrows,285;pigment,291;colour,293;A. marina,333;habits,301;in brackish water,284;as bait,297;eggs,314Arenicolidae,258,333Argilophilus,372Arhynchidae,185Arhynchus hemignathi,181,185Aricia, otocyst,273;eggs,275Ariciidae,258,321;gill,265Aristotle, on Earthworms,347Armata,445,446Arthropoda, absence of cilia in,124Articulata,517,518Ascaridae,131,138,163Ascaris,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,125,126,141Ascodictyon,521n.Ascomorpha,223Ascopodaria,488n.Asellus, Rotifers attached to,227Asexual reproduction, in Triclads,40;in Rhabdocoels,44;in Cestodes,80;inTrichoplaxandSalinella,96;in Polychaeta,278f.,279,280,282,340;in Oligochaeta,374,375,377;in Polyzoa,496,514Aspidobothridae,73Aspidocotyle,73Aspidocotylea,73Aspidogaster,63,73Aspidosiphon,421,423,424,425,428;commensalism of,429Asplanchna,200,205,210,213,215n.,223,226Asplanchnaceae,203,212,220,222Asplanchnidae,200,201,203,205,211,212,216,223,226,230Asplanchnopus,201,211,222,223,226,230Ass, parasites of,140Association, of Rhabdocoels with Lamellibranchs and Sea-urchins,45;ofMonotus fuscuswith littoral animals,46;significance, in Turbellaria,51—see also Commensal and ParasiticAsteroids, as hosts,341Asterope,315Astropecten, as host,297,309Atokous phase,277n.Atractonema,131,150,152,153Atrium (genital), inPlanaria,38,39;in Oligochaeta,361,378Atrochus,201,213,214,221Auditory organs, of Turbellaria,26;of Hoplonemertea,106,110;of Nematoda,128;of Polychaeta,273Aulastomum,393,399,403Auricles, of Rotifers,205Autolytus,308;eye,255;denticles,270;brood-sac,275,276;reproduction,278,279;sexual dimorphism,281;A. ebiensis, eggs,276Automolos, British species,50Avenella,533Avicularian zooecium,482,524Avicularium,466,467,468,482f.,482,516,517,522f.,524;adventitious,482;vicarious,482;vibraculoid,484,485;structure,483;movements,485;function,486Axine,56,73Axiothea,332,333Baely, on human parasites,139Baird, on Oligochaeta,382Bait, Polychaeta as,297Baker, on Rotifers,197,207; on Polyzoa,496 n.Balanoglossus, affinities of Nemertinea with,120Balatro,204,212,224,227Balfour, on Trochosphere,229Barentsia,488n.Barrois, on Polyzoa,509Basement-membrane, ofLeptoplana,11,12;of Nemertines,102,103,110f.
Acanella, as host,298
Acanthobdella,395
Acanthocephala,123,124,174f.;
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,16f.,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,66n.
Allolobophora,351,367,369,371,386,389,390f.;
cocoons,365
Allostoma pallidum,50
Alluroides,379
Allurus,351,366,370,389;
cocoons,365
Alma,352f.,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,260,273n.;
head,262,263;
parapodium,264;
cirri,265;
chaetae,267,267;
inLepas,297
Amphiporus,102,114;
British species,110
Amphiptyches,77
Amphistomatidae,73
Amphistomum,71,73;
A. hominis,63
Amphitrite,327,328;
gill,329
Ampullaria,Temnocephalawith,53
Anachaeta,350,376,395
Anal, cirri,259;
funnel,259,332,333;
vesicles,358,436
Anangian worms,253
Anarthropora,529
Ancylostomum,143,163
Andrews, onSipunculus,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,76n.,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 polymorphusin,77
Apsilidae,201,203,214,220,221
Apsilus,201,212,213,214,221
Arabellites,302
Arachnidium,532
Archiannelida,241;
anatomy,243f.;
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,266f.;
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,521n.
Ascomorpha,223
Ascopodaria,488n.
Asellus, Rotifers attached to,227
Asexual reproduction, in Triclads,40;
in Rhabdocoels,44;
in Cestodes,80;
inTrichoplaxandSalinella,96;
in Polychaeta,278f.,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,200,205,210,213,215n.,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;
ofMonotus fuscuswith 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,277n.
Atractonema,131,150,152,153
Atrium (genital), inPlanaria,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,466,467,468,482f.,482,516,517,522f.,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,488n.
Barrois, on Polyzoa,509
Basement-membrane, ofLeptoplana,11,12;
of Nemertines,102,103,110f.