613 



Olividce, 6 



Ollacrinus (see Gilbertsocrinus) 



Ommastrephes, 24 ', gonad, female, 230 ; 



shell, section, 69 

 Ommatophore, 102 



Ommatostrephes, 24 ', nervous system, 148 

 Oncidiella, 46 

 Oncidiidce, 8 

 Oncidium, 44, 104 



,, celticum, genital organs, 235 ; 



larva, 256 



Oneirophanta mutabilis, rod, 237 

 Onychoteuthis, 24 

 Operculum, 31 

 Ophiacantha, 300 



,, marsupialis, 495 ; vivipara, 



495 

 Ophiactis, 300 



Mullen, 506 

 poa, 300 

 Savigny, 506 

 virens, 498 ; disc, section, 426 

 Ophiarachna incrassata, vertebral ossicles, 



356 



Ophidiaster Gertnani, 421 

 Ophioceramis, 327 

 Ophiocnida, 300 



sexradia, 506 



Ophiocoma, 300 



pumila, 506 

 ,, Valencia;, 506 ; 



Ophiocreas, 301 

 Ophioderma ( = Ophiura}, 495 

 Ophiodiaster, 298 



diplax, regeneration of arms, 



505 

 Ophioglypha, 300 ; bursa, 495, 496 ; disc, 



section, 497 



albida, stomach, 494 



,, hexactis, 495 



lacertosa, ovary, section, 497 



Ophioglyphidce, 300 

 Ophiohelus umbella, arm joint, 357 

 Ophiomastix, 327 

 Ophiomitra exigua, 327 

 Ophiomusium, 300 



validum, apical system, 327 



Ophiomyxa, 300 



vivipara, 495 



Ophiomyxidce, 300 

 Ophionereis, 422 

 Ophioplocus, 422 



Ophiopteron elegans, brachial joints, 391 

 Ophiopya longispinus, oral skeleton, 359 

 Ophiopyrgus, 327 

 Ophioihela dividua, 506 

 ,, isidicola, 506 

 Ophiotlwlia, 392 

 Ophiothrix, 300 



fragilis, ambulacral tentacle, 



section, 466 ; nervous sys- 

 tem, 456 

 Ophiozona, 300 



VOL. II 



Ophiura, 300 



Ophiurce, 300 



Ophiuroidea, 299-301 ; arm, section, 412 ; 

 arm, joint, 357 ; disc, section, 486 : 

 Pluteus, 533 ; nervous system, 456 ; 

 ring sinus, 496 



Opisthobraiichia, 10, 33 ; heart, 199 



Opisthopneumonia, 76 



Oral angle plates, 358 

 lobes (Lam.), 105 



Orocystis Helmhackeri, 313 



Orophocrinus, 315 



stelliformis, 314 



Orphnurgus, 418 



Ort/wceras group, 68 



Orthopsis, 299 



Oscainius, 10 



Osphradium, 84, 162-164 



Ostracoteuthis, shell, section, 69 



Ostrea, 17 



edulis, anatomy, 16 



Ostreidce, 17 



Owenia, 24 



Oxygyrus, 108 



Oxynoe, 12 



Oxynoidea, 12 



PAL&ASTER, 295 

 Palceasteroidea, 295 

 Palceechinoidea, 288 

 Palceechinus, 289 



elegans, 289 



Palceobrissus, 293 

 Palczocoma, 295 

 Palceocrinoidea, 303 

 Palceopneustes, 293 



Murrayi, 294 



Palceostoma, 295 

 Palceotropus, 429 

 Pallial cavity, 26 ; line, 64, 124 ; sinus, 



64, 124 



Palliata ( = Tectibranchia), 46 

 Pallium, 26 

 Palmars (Grin.), 371 

 Palmipes, 297 

 Paludina, ctenidium, 85 



vivipara, circulatory system, 

 203 ; development, 252, 254, 

 255 



Paludinidce, 5 

 Pancreas (Ceph.), 196 

 Pandoridce, 21 

 Pannychia, 285 

 Papulse, 439 

 Paractinopoda, 288 

 Paramenia impexa, 216 



palifera, 184 

 Parameniidoe, 3 

 Parapodia, 106 

 Pararchaster, 296 

 Parasalenia, 290 



Parasira (Tremoctopus) catenulata, 230 

 Parelpidia, 418 



2 R 2 



