686 



INYEKTEBEATA 



Post-oral arms in larva of Asterias, 465 ; of 

 larva of Echinus esculentus, 508 ; of larva 

 of Ophiothrix fragilis, 490 ; of larva of 

 Synapta digitata, 533 



Post-oral band of cilia in larva of Asterias, 

 464 



Post-retinal layer, formation of, in central 

 eyes of Agelena, 234 



Prae-oral arras of ciliated band in larva of 

 Asterias, 464 ; in larva of Echinus escu- 

 lentus, 509 ; in larva of Synapta digitata, 

 533 ; in New England Tornaria, 576 



Prae-oral band of cilia in larva of Asterias, 

 464 ; in larva of Phascolosoma, 376 



Prae-oral coelom of Actinotrocha larva, 

 381 



Prae-oral lobe, disappearance of, in Actino- 

 trocha larva, 383 ; of larva of Asterina 

 gibbosa, 473 



Prae-oral loop of ciliated baud in larva of 

 Asterias, 464 ; in larva of Synapta 

 digitata, 532 ; of New England Tornaria, 

 576 



Pre-anal spine of Nauplius larva of Cirripedia, 

 202 



Pre-antennae of Scolopendra, 282 



Premandibular cavities of Vertebrata, 606 



Preservation of eggs, methods of, for Amphi- 

 oxus lanceolatus, 587; for Antedon rosacea, 

 545 ; for Ascaris megalocephala, 438, 439 ; 

 for Astacus, 178, 179 ; and larvae for 

 Asteroidea, 458, 459, 460 ; for Aurdia 

 aurita, 67 ; for Cynthia partita, 609 ; for 

 Donacia, 245 ; for Dreissensia, 333 ; for 

 Fiona, 320 ; and embryos and larvae for 

 Grantia, 38 ; for Patella, 292 ; for Physa, 

 320 ; for Polygordius, 129, 130 ; for 

 Sagitta, 428 ; for Urticina crassicornis, 76 



Priapuloidea, 163, 372 



Primary body - cavity, 165 ; of larva of 

 Asterias, 4(51 



Primary cerebral ganglion of Astacus, 184 



Primary dorsal organ, formation of, in em- 

 bryo of Donacia, 247 



Primary germ-cells, formation of, in Phyllo- 

 dromia, 262 



Primary germinal involution of Asterina 

 gibbosa, 481 



Primary gill-slits, formation of, in larva of 

 Amphioxus lanceolatus, 590 



Primary madreporic pore, formation of, in 

 embryo of Antedon rosacea, 547 ; in larva 

 of Asterias, 465 ; in larva of Ophiothrix 

 fragilis, 489 



Primary mesenchyme, formation of, in larva 

 of Echinus esculentus, 507 ; in Ophiothrix 

 fragilis, 486 



Primary mesoderm, formation of, in Astacus, 

 181 



Primary radial plates, formation of, in 

 Antedon rosacea, 556 



Primary stomodaeum, formation of, in 

 Callidina russeola, 422, 423 



Primary trochoblasts, formation of, in Orepi- 



dula, 321 ; in Fiona, 321 ; in Po.tella, 



295 ; in Phascolosoma, 374 

 Primary yolk pyramids of egg of Astacus, 



180 ; of eggs of Scolopendra, 281 

 Primitive anus, formation of, in Polygordius, 



139 

 Primitive cumulus, formation of, in embryos 



of Agelena, 224 ; in embryos of Donacia, 



247 ; in embryos of Pedipalpi, 241 ; in 



embryos of Scorpion, 240 

 Primitive germ-cells, definition of, 2 

 Primitive mouth, formation of, in Poly- 

 gordius, 139 

 Primitive streak in eggs of Cephalopoda, 356 ; 



in embryo of Ageleno,, 223 ; in embryos 



of Pedipalpi, 241 ; in embryos of Peri- 



patus capensis, 171 ; in embryos of 



Scolopendra, 282 

 Principal retractor muscles of Trochophore 



larva of Phascolosoma, 376 

 Proboscis, formation of, in Callidina russeola, 



424 ; in Nemertiuea, 123 ; in New England 



Tornaria, 577 

 Proboscis cavity, formation of, in Balano- 



glossus clavigerus, 571 

 Proboscis pore, formation of, in Balanoglossus. 



clavigerus, 572 

 Proboscis sheath, formation of, in Nemertinea, 



123 

 Proctodaeum, formation of, in Agelena, 226, 



231 ; in Astacus, 183 ; in Bombyn, 280 ; 



in Callidina russeola, 425 ; in Donacia, 



253, 254 ; in Dreissensia, 337 ; of larva 



of Galerucella ulmi, 269 ; in Cyphonautes 



larva of Membranipora, 390 ; in Pedicellina 



echinata, 400; in Peripatus capensis, 175 

 Progoneata, 280, 281, 285 

 Pronephros, 162 

 Prosobranchiata, 291, 320, 324 

 Protandrous, definition of, 2 

 Protista, 660 

 Proto-annelida, 416 

 Protobrauchiata, 349 

 Protocephalic region of embryo of Donacia, 



251 

 Protocerebrum of Astacus, 184 ; of Donacia, 



258 ; of Scolopendra, 283 

 Protochordata, 381 ; development of, 568- 



648 



Protocoelomata, 436 ; defined, 661 

 Protocormic region of embryo of Donacia, 



251 



Protogynons, definition of, 2 

 Protonemertinea, 118 

 Protonephridium of Echiuroidea, 163 ; of 



Polygordius, 145 ; of Polygordius appen- 



diculatus, fate of, 150 ; of Polygordius 



lacteus, fate of, 152 

 Protostigmata, formation of, in dona intesti- 



nalis, 627 ; in larva of Doliolum, 637 

 Prototracheata, 169, 170 

 Prototroch, of Polygordius a^ppendiculatus, 



destruction of, 150 ; disappearance of, in 



larva of Phascolosoma, 377, 378 ; forma- 



