684 



IN VERTEBRA TA 



Pachynema, definition of, 4 



Pachytene threads, definition of, 4 



Paguridae, 216 



Paired tube-feet, formation of, in Asterias, 

 471 ; in Asterina gibbosa, 477 ; in Gucu- 

 muria planci, 542 ; in Echinus esculentus, 

 517 ; (tentacles) in Opldothrix fragilis, 

 495 



Palatmon, 192, 243 



Pali, formation of, in Caryophyllla cyathus, 88 



Palinurus, 214 



Pallene, development of, 243 



Pallial budding in Urochorda (Botryllidae), 

 637 



Paludina, 319, 323, 335, 383, 415 ; de- 

 velopment of, 309-318 



Pantopoda, 169, 285 ; development of, 242, 

 243 



Paragaster of Sycandra raphanus, 43 



Paragastric canals, formation of, in Beroe, 

 94 ; of Ctenophora, 561 



Paraneuroptera, 245, 272, 277 ; embryonic 

 development of, 266 



Parasyndesis, definition of, 4 



Parenchyma, formation of, in Nephelis, 163 ; 

 definition of and formation of, in Plano- 

 cera, 168 



Parenchyma-like tissue of larva of Bertie, 93, 

 95 



Parthenogeuetic ovum(a), definition of, 2 



Patella, 304, 310, 314, 317, 319, 321, 322, 

 323, 330, 332, 334, 335, 341, 375 ; de- 

 velopment of, 291-303 



Patella coerulea, 291, 292 



Patella vulcjata, 291, 303 



Pauropoda, 280, 281 



Pea-plant, self- fertilized, 18 



Pea-plants result of crossing, 1 6 



Pecten, 348 



Pectines of Scorpion, formation of, 241 



Pectinibranchiata, 291 



Pedal disc, formation of, in Urticina crassi- 

 cornis, 81 



Pedal ganglia, formation of, in Dentalium, 

 329 ; in Dreissensia, 342 ; in Loligo, 358 ; 

 in Paludina, 315 ; in Patella, 301 



Pedicellariae of Echinus esculentus, forma- 

 tion of, 515 



Pedicellina echinata, development of, 398- 

 403 



Pedipalpi, 221, 241 



Pelagia, development of, 72, 73 



Pelecypoda, 291, 463 ; ancestors of, 368, 

 369 ; development of, 332-353 



Pelmatozoa, 456, 560, 564 

 Penaeidea, 177, 203, 208, 213 

 Penaeus, 655 ; Nauplius of, 22 

 Penetration path of spermatozoon in egg of 



Cynthia partita, 611 

 Pennaria, 61 



Pentacrinoid larva of Antedon rosacea, 558 

 Pentacrinus, 558, 559 

 Pentacula, definition of, 539 

 Pentastomida, 221 242 



Peracarida, 177, 219 



Pericardial cavity, formation of, in Astacus, 

 187 



Perieardial sac, formation of, in Chiton poiii, 

 320 ; in embryo of Paludina, 311 



Pericardial septum, formation of, in Donacia, 

 257 ; in Peripatus capensis, 174 ; in 

 Phyllodromia, 263 ; in Scorpion, 241 



Pericardium, formation of, in Ciona in- 

 testinalis, 626 ; of Cyclas, 350 ; in Dolicho- 

 glossus koicalevskii, 583 ; in Dreissensia, 

 344 ; in Loligo, 362 ; in Paludina, 314 ; 

 in Peripatus capensis, 174 ; in Cyatho- 

 zooid of Pyrosoma, 634 ; in Scorpion, 241 ; 

 in New England Tornaria, 575 ; in Unio, 

 353 



Perihaemal ring - canal, formation of, in 

 Ophiothrix fragilis, 494 



Perihaemal spaces, formation of, in Asterina 

 gibbosa, 474 ; in Ophiura brevispina, 502 



Peri-oral coelom, formation of, in Asterias, 

 469 ; in Asterina gibbosa, 474 ; in Ophio- 

 thrix fragilis, 497 ; in larva of Synapta 

 digital, 536 



Peripatus, 157, 187, 190, 204, 230, 232, 

 241, 244, 254, 257, 258, 261, 281, 283, 

 285, 287 



Peripatus capensis, 167, 177, 657 ; develop- 

 ment of, 170-176 



Peripatus novae- zelandiae, 226 



Peripheral rosettes, formation of, in segment- 

 ing eggs of Gastropoda, 322 ; in seg- 

 menting eggs of Phascolosoma, 374 



Periplasm of egg of Agelena, 222 



Periproct, formation of, in Echinus esculentus, 

 518 



Perisarc, formation of, in Tubularia, 57 



Peristome, formation of, in shell of Acmaea, 

 304 ; in shell of Fissurella, 305 ; in shell 

 of Haliotis, 305 



Perivisceral cavity, formation of, in Peri- 

 patus capensis, 174 



Permanent anus, formation of, in Polygordius, 

 140, 142, 144 



Perophora, 638, 644 



Per- radial lobe of stomach of Aurelia, 71 



Phallusia, 609, 631 



Phallusia mammillata, 619 



Pharynx, formation of, in Agelena, 235 ; in 

 Amphioxus lanceolatus, 596 ; in larva of 

 Cynthia partita, 614; in larva of Doliolmn, 



637 ; in Cyathozooid of Pyrosoma, 634 ; 

 in Salpa, 636; in blastozooid of Urochorda, 



638 ; in Yungia, 114 



Phascolosoma, 385 ; development of, 372-380 

 Phascolosoma gouldii, 373 

 Phascolosoma vulgare, 373 



Ptwlas, 348 



Phoronidea, 372 ; development of, 380-385 



Phoronis, 406, -560 ; development of, 380- 

 385 



Phorozooids of Doliolum, 641 



Phosphorescent organs, formation of, in Pyro- 

 soma, 632 



