INDEX 



553 



Pla.costeyus, colour, 292 ; from deep sea, 

 300 



Placiinetta, 73 



PlMjiochaeta, 358, 381, 3S4 



I'layiostoma, 46 ; British species, f>0 



Plagiostomatidae, 50 



Planaria, 30, 31 f., 39 ; British species, & 



1'lanariaus, 3, 7 ; iJinophilus, compared 

 with, 242, 243 



Plnnariidae, 42 



Planctoplana, 19 



Plankton, Rotifers in, 225 



Planocem, 18, 19, 20 



Plauoceridae, 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 



Pleionog aster, 381 



Plerocercoid larva, 84 



Plessis, dn, on Tetrastemmalacwstre, 101 n., 

 118 



Pleurocotyle, 73 



Pleurotrocha, 224, 226 



Ploesomu, 212, 225 



Ploima, 202, 203, 212, 213, 216, 320, 22$, 

 226, 227 



Plu-nuitella, 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, 285, 272 ; 

 ciliated pits, 272 ; alimentary canal, 

 with pharynx, 249, 250, 251, 269, 270, 

 271 ; oesophageal glands, 271 f. ; 

 nephridium, 253, 254, 269, 274 ; geni- 

 tal duct, 254, 269 ; genital cells, 256, 

 273 f. ; hermaphrodite, 273 ; regenera- 

 tion, 278, 282 ; habits, 285 ; carnivor- 

 ous, 304 ; distribution, 299 ; from fresh 

 water, 284 ; from deep sea, 300 ; pelagic, 

 291, 314 ; boring, 287 ; tubes, 287 ; pig- 

 ments, 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, 275, 300 , 

 provisional chaetae, 274 



Polychoerus, 49 ; development of, 44 n. 



Polycirrus, 330; habits of, 285; P.auranti- 

 aciis, warning colours, 294 ; phosphor- 

 escence, 295 ; /'. haematodes, coelomic 

 corpuscles, 253 



Polycladida (Polyclads), 4 f., 7 ; classifica- 

 tion, 16 f. ; development, 28 f. ; British 

 species, 19, 20, 22 



Polydadus, 42 



Polycotyle, 73 



Polydma ( = Leucodore), 323; frontal 

 ridge, 260 ; head, 261 ; special chaetae, 

 267 ; with JJeliopora, 298 ; P. ciliata, 

 borings, 287 



Polydoridae, 258, 323 



Polygordius, 242, 244 ; development, 245 



Polymnia, 328 



Polymorphism, of Nereis, 277 



Polymyarii, 137, 142 



Polynoe 310 ; segment-:, 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.; 1\ 

 sqiM-mata, 309 ; elytron, 310 ; P. clava, 

 elytron, 310 ; P. imbritata, 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 ; phosphor- 

 escence, 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 a pannache, 496 



Polypide, 468, 469, 474, 488, 523 ; retrac- 

 tion and protrusion, 498 f. 



Polypide-bud, 468, 472, 487, 496, 499, 

 501, 510 ; connected with reproduction, 

 507 



Pulypostia, 19 ; penes, 27 



Polystomatidae, 53, 55, 73 



Polystomatinae, 73 



J'olystomum, 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 vibra- 

 cula, 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 



