INDEX 



685 



Phylactolaemata, 385, 386, 396 



Phyllocarida, 177 



Phyllodroinia, 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 



Pilidiiim 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 embrvo of Scdpa, 



635 

 Plaice, 22 



Plakina, development of, 44 

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

 Pkmorbis, 322 

 Planula larva, definition of, 60 ; developed 



from egg of free Medusa, 60 ; of Siphono- 



phora, 65 ; compared to embryo of Cteno- 



phora, 96 ; interpretation of, 98, 99 

 Platvctenea, 63 

 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 Lolirjo, 358 ; in PaZudina, 315 

 Pleuron, formation of, in I/imultts, 23S 

 Pleuronectes, 22 

 Plexus of muscles in larva of Polygordius 



appendiculalus, 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, 826 ; 



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



anassa, 332 

 Polian vesicle, formation of, in Synapta 



digitata, 538 

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



development of, .153-156 

 Polyclada, 102, 117, 164 ; development of, 



103-115 

 Polygm-dius, 106, 153, 154, 155, 156, 158, 



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



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



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

 Polygordius appendiculalus, 162 ; later 



larval development of, 144-152 



Polygordius lacteus, 144 ; metamorphosis of, 

 152 ; later larval development of, 161, 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, 166 



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 Eiitoprocta, 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 ofAsterias, 

 465 ; in larva of Ophiothrix fragilis, 489 ; 

 in Ophiura brevispiTta, 501 



Pores of shell of Terebi^alulina septentrionalis, 

 413 



Porifera, 116, ,660 ; compared with Coelen- 

 terata, 63 ; 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 Ijm-yphora, 261 ; in 

 embryo of Odonata, 266 



Posterior ciliated epaulettes, formation of, 

 in larva of Echinus esculentus, 616 



Posterior endodermio thickening, formation 

 of, in embryo of Donacia, 253 



Posterior funnel fold in embryo of Loligo, 

 357 



Posterior mantle-groove of Terebratulina 

 septentrionalis, 410 



Posterior mesenchyme, formation of, in em- 

 bryo of Cynthia partita, 615 



Posterior mesoderm, formation of, in embryo 

 of Ascaris megalocephala, 445 



Posterior sinus, formation of, in Loligo, 362 



Posterior vacuolated crest in larva of Ophio- 

 thrix fragilis, 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, 609 



Postero-lateral arms of ciliated band of larva 

 of A sterias, 465; of larva of Echin ocardium 

 cordatum, 522 ; of larva of Ophiothrix 

 fragilis, 487; of larva of Synapta digitata, 

 633 ; of New England Tornaria, 676 



Postero-lateral rods in larva of Ophiothrix 

 fragilis, 487 



Post-larval development of Asterina gibbosa, 

 479, 480; of Echinus esculentus, 520, 621 



Post-oral arm of Pacific Tornaria 581 



