806 



INDEX 



Nyctiphanes, 554 

 Nyctotherus, 94, 96, 97 

 Nymphon hispidum, 657 



0, 



'BF.LIA, General structure, 129, 130, 

 131 : Microscopic structure, 132, 133 : 

 Medusae, 135, 136, 137 : Comparison 

 of polype with medusa, 137, 138, 139 : 

 Reproduction, 139 : Development, 

 140 : Systematic position, 143 



Occlusor muscle, 342 



Ocelli, 143, 172 



Octopoda, 663, 767*, 768, 769, 770,773, 

 780 



Octopus, 768, 770, 772, 773 



Oct or chandra, 150 



Ocular plates, 388, 389 



Odonata, 6J8 



Odontophore, 702, 707, 708, 709. 



(Esophagus See Digestive system 



Oikomonas, 73, 75 



Olfactory organs, 39* 



Olfactory pits, 172* 



Oligochaeta, 455*, 457, 460, 461, 462, 

 463, 464, 466, 467, 468, 469, 470, 

 471, 475, 476, 477 



Olynthus, 117 



Ommatidium, 523*, 524 



Oncidium, 727, 735 



Oniscus, 554, 569, 572 



Onychophora, 515,591*, 661 SeePm- 

 patus 



Ocecium, 334* 



Ookinete, 89* 



Oosperm, 23* 



Oostegites, 570* 



Oostegopod, 519* 



Ootype, 239, 240 



Opalina, 95, 100 



Opalinopsis, 96 



Operculum, of Radiolaria, 62*, 64 : 

 Ciliata, 97, 98 : Gastropoda, 704*, 

 705, 720 



Ophioglypka, 411 



Ophiuroidea, 368, 402* : Distinctive 

 characters and classification, 402* : 

 General form and symmetry, 406, 

 407, 408 : System of plates, 409 : 

 Modifications of form, 410, 411, 

 412 : Ooplome, 416 : Ambulacra! 

 system, 417 : Blood-vascular sys- 

 tem, 417, 418 : Haemal system, 

 418 : Axial organ, 419 : Enteric 

 canal, 419 : Nervous system, 420 : 

 Reproductive organs, 420 : De- 

 velopment, 422, 423 : Ethology, 

 &c., 425, 426 



Ophrydium, 97, 99 



Ophryodendron, 102 



Ophryoglena, 96 



Opisthobranchia, 714*, 718, 724, 725, 



735 



Opisthogoneata, 599*, 602, 661 

 Opisthorchis sinensis, 280 

 Optic gland, 750 

 Optic nerve-fibres, 750 

 Optic vesicle, 779 

 Oral arms, 169* 

 Oral surface, 369* 

 Oral tentacles, 151, 413 

 Orchestia, 554, 569, 579 

 Order, 4* 

 Organ of Bojanus, 672* : of Owen, 



758* : of van der Hoeven, 758* : 



of Valenciennes, 759 

 Organic evolution See Evolution 

 Organism, 1* 

 Organ-pipe Coral, 193 

 Organs, 31* 

 Oriental region, 9* 

 Orobdella, 504 

 Orthoceras, 780 



Orthonectidce, 227, 229, 230, 231 

 Orthoptera, 616*, 621, 624, 625, 637 

 Orthopteroidea, 616* 

 Oscarella, 118 

 Oscaria, 116 

 Oscillatoria, 74 

 Oscular sphincter, 112* 

 Osculum, 107* 



Osphradium, 673*, 674, 712, 774 

 Ossicles, 368* 

 Ostia, 107*, 110, 521 

 Ostium, 186* 

 Ostracoda, 550*, 558, 559, 578, 579, 



581, 582, R86, 587 

 Ostrea, 678, 680, 683, 688, 690, 691 

 Otocyst, 40*, 467, 673, 674. 689 

 Ovariole, 612*, 631 

 Ovary, 40* 

 Ovicells, 345* 

 Oviduct, 40*, 240 

 Oviparous, 40* 

 Ovipositor, 594 

 Ovum, 20*, 21, 31 

 Owen, organ of, 758* 

 Oxeote spicules, 109, 111* 

 Oxygen, oxidation, 36, 37 

 Oxyuris, 302 

 Oysters, 663, 678, 680 



JL ACHYCHALINA, 121 

 Paedogenesis, 42*, 223*, 632 

 Pagurvs, 555, 574 

 Palaearctic region, 9* 

 Palcemon, 555, 573 

 Palcemonetes, 578 

 Palaeodictyoptera, 637 

 Palaeontology, 6* 



