INDEX 



685 



Phylautolaemata, 385, 386, 396 



Phyllocarida, 177 



Phyllodromia, development of genital organs 



of, 262, 263 

 Phyllopoda, 177, 185, 193, 211, 655 ; larval 



history of, 200-201 

 Phyllosoma, larva of Loricata, 214 

 Physa, 291, 312, 320, 323, 338, 340 

 Physalia, 64 



Pilidium larva, 118, 164 ; ancestral signific- 

 ance of, 127 ; development of, of Cere- 



bratulus lacteus, 120 ; metamorphosis of, 



122-124 ; resulting from fragments of egg 



and isolated blastomeres, 125 

 Pinnules of Antedon rosacea, formation of, 



557 

 Piriform organ, formation of, in Cyphonautes 



larva, 390 

 Pisidium, 349 

 Placenta, formation of, in embryo of Salpa, 



635 



Plaice, 22 



Plakiiia, development of, 44 

 Planocera, 161,332 ; development of, 103-112 

 Planorbis, 322 

 Planula larva, definition of, 60 ; developed 



from egg of free Medusa, 60 ; of Siphouo- 



phora, 65 ; compared to embryo of Cteno- 



phora, 96 ; interpretation of, 98, 99 

 Platyctenea, 53 

 Platyhelminthes, 118, 157, 161, 164, 320, 



424, 600, 635, 661 ; development of, 102- 



117 ; evolution of, 115-117 

 Pleopods, formation of, in Astacus, 188 

 Pleural ganglia, formation of, in Dreissensia, 



342 ; in Loligo, 358 ; in Paludina, 315 

 Pleuron, formation of, in Limulus, 238 

 Pleuronectes, 22 

 Plexus of muscles in larva of Polygordius 



appendiculatus, 148 

 Ploima, 418 

 Pluteus paradoxus, 489 

 Podarke, 129 

 Podaxonia, 406, 407, 415, 416; development 



of, 372-385 

 Podocoryne, 72 ; development of Medusa of, 



61 



Poison-gland, formation of, in Agelena, 235 

 Polar bodies, homologies of, 13 

 Polar lobe in egg of Dentalium, first, 326 ; 



second, 326 ; third, 327 ; in the egg of Ily- 



anassa, 332 

 Polian vesicle, formation of, in Synapta 



digitate, 538 

 Polychaeta, 128, 161, 205, 211, 285, 372; 



development of, 153-156 

 Polyclada, 102, 117, 164 ; development of, 



103-115 

 Polygordius, 106, 153, 154, 155, 156, 158, 



161, 163, 164, 165, 166t 293, 294, 299, 



301, 305, 306, 310, 321, 323, 324, 335, 



343, 387, 388 ; development of, 128-153 

 Polygordius appendiculatus, 152 ; later 



larval development of, 144-152 



Polygordius lacteus, 144 ; metamorphosis of, 

 152 ; later larval development of, 151, 152 



Polyphemus, 193 



Polypide in Polyzoa, 644 ; formation of, 

 in Cyphonautes larva, 394 ; in Polyzoa 

 Ectoprocta, 396 



Polyplacophora, 291 



Polytrochal larva, definition of, 153 ; of 

 Nereis, 156 



Polyzoa, 560, 562, 569, 608, 644, 655 ; de- 

 velopment of, 386-403 



Polyzoa Ectoprocta, 372, 386, 403, 405, 406, 

 656 ; development of, 387-396 



Polyzoa Entoprocta, 385, 386, 564, 622 ; de- 

 velopment of, 398-406 



Pomatoceros, 129^130, 131, 155 



Pontophilus, Mysis larva of, 215 



Porania pulvillus, 472 



Pore-canal, formation of, in larva of Asterias, 

 465 ; in larva of Ophiothrix frag His, 489 ; 

 in Ophiura brevispina, 501 



Pores of shell of Terebratulina septentrionalis, 

 413 



Porifera, 116, 660 ; compared with Coelen- 

 terata, 53 ; development of, 37-52 



Porocyte, ancestral meaning of, 52 



Porocytes of Grantia, 43 



Portunion, development of, 219, 220 ; young 

 and adult stages of contrasted, 22 



Posterior amniotic fold in embryo of Donacia, 

 249 ; in embryo of Doryphora, 261 ; in 

 embryo of Odonata, 266 



Posterior ciliated epaulettes, formation of, 

 in larva of Echinus esculentus, 515 



Posterior endodermic thickening, formation 

 of, in embryo of Donacia, 253 



Posterior funnel fold in embryo of Loligo, 

 357 



Posterior man tie -groove of Terebratulina 

 septentrionalis, 410 



Posterior mesenchyme, formation of, in em- 

 bryo of Cynthia partita, 615 



Posterior mesoderm, formation of, in embryo 

 of A scar is megalocephala, 445 



Posterior sinus, formation of, in Loligo, 362 



Posterior vacuolated crest in larva of Ophio- 

 thrix frag ilis, 488 , 



Postero-dorsal arms of ciliated band in larva 

 of Asterias, 465 ; in larva of Echinus 

 esculentus, 509 ; of larva of Ophiothrix 

 fragilis, 490 ; of larva of Synapta digitata, 

 533 



Postero-dorsal rods in larva of Echinus 

 esculentus, 509 



Postero-lateral arms of ciliated band of larva 

 of A sterias, 465; of larva of Echinocardium 

 cor datum, 522 ; of larva of Ophiothrix 

 fragilis, 487; of larva of Synapta digitata, 

 533 ; of New England Tornaria, 576 



Postero-lateral rods in larva of Ophiothrix 

 fragilis, 487 



Post-larval development of Asterina gibbosa, 

 479, 480; of Echinus esculentus, 520, 521 



Post-oral arm of Pacific Tornaria 581 



