748 INDEX 
Neolebias, 576 
Veopempheris, 637 
Neopercis, 705 
Neoscopelus, 611 
Neostlurus, 588 
Nephridia, of Amphioxus, 125 
Nephrostomes, 398 ; persistent, 401 
Nephrotome, 397, 398 
Nerophis, 634, 635 
Nerve eminences, 383 
Nervous system, of Chordata, 4; of Hemi- 
chordata, 9, 25, 30; of Tunicata, 53, 
58, 66 ; of Amphioxus, 127 f., 131 ; of 
Fishes, 367 f. 
Nesiarchus, 679 
Nesting habits of Sticklebacks, 630 
Nests of Fishes, 414 f., 427, 500, 501, 514, 
515, 517; of Arius, 593; of Doras and 
Callichthys, 592; of Gobius, 690; of 
Gymnarchus, 552; of Heterotis, 558 ; of 
Spinachia, 631 
Nettastoma, GOL 
Nettenchelys, GUL 
Nettophichthys, 601 
Neural gland, 52 
Neurenteric canal, 57, 131, 133 
Neuromeres, 195 n. 
Neuropore, 10, 58, 59 
Nilhechte, 550 
Nilsson, 715 
Niphon, 659 
Nishikawa, 685 n. 
Noll, 584 n. 
Nomeus, G43; N. gronovii, 643 
Norman, 23 
Notacanthidae, 624 
Notacanthus, 625 ; N. bonapartti, 625 
Wotagoqus, 498 
Notidanidae, 442, 279; persistent nephro- 
stomes, 401 
Notidanus, 443, 345°; spiral valve, 267 ; 
N. cinereus, branchial clefts, 277 ; 
skull, 222; N. griseus, branchial clefts, 
277 
Notochord, 3; of Enteropneusta, 14; of 
Cephalodiscus, 24, 25; of Rhabdopleura, 
27; of Actinotrocha, 28; of Tunicata, 
57, 60, 61; of Amphioxus, 119, 118, 
119, 132 ; of Fishes, 193 f. 
Notoglanidium, 588 
Notoglanis, 588 
Notogoneus, 572 
Notopteridae, 554, 544, 303, 389, 405 
Notopterus, 555, 153, 305, 306; N. afer, 
skeleton, 554; .V. chitala, 555 
Notothenia, 706 
Nototheniidae, 705, 704 
Noturus, 588, 590 
Novacula, 673 
Nucleus, of Thaliacea, 101, 105 
“Nuria, 582 
Nurse, 97 
Oar-Fish, 715, 163 
Oblata, G64 
Ocelli, 53 
Octacnemidae, 708, 101 
Octacnemus, 109, 101; O. bythius, 109 ; 
O. patagoniensis, 109 
Odax, 674 
Odaxothrissa, 563 
Odontaspis, 451 
Odonteus, 673 
Odontonectes, 660 
Odontostomus, 611, 613 
Oenoscopus, 545 
Oesophageo-cutaneous duct, 281 
Oikoplasts, 65 
Oikopleura, 68, 67, 69 ; transverse section, 
67 ; longitudinal section, 68; 0. copho- 
cerca, 66; O. diowa, 70; O. flabellum, 
transverse section, 69 
Olfactory organs, 155, 390 f., 391, 392 
Olfactory pit, 129 
Oligopleuridae, 545, 544 
Oligopleurus, 543 
Oligorus, 659 
Oligosarcus, 575 
Oligotrema, 7S, 111 un. 
Olt, 584 n. 
Olyra, 588 
Omble Chevalier, 567 
Omiodon, 611 
Omosudis, 611 
Oncorhynchus, 566 
Onetrodes, 719; O. eschrichtti, 174 
Onus, 648 5 coloration of larvae, 175 
Oozooid, 84, 91, 93 
Opah, 628, 164 
Operculum, 25, 155, 278, 282, 283 
Ophichthys, 601 K 
Ophidiidae, 723, 651, 702, 704, 163, 
361 
Ophidium, 713, 361 ; air-bladder, 502 
Ophioblennius, 709 
Ophiocephalidae, 644, 637, 163, 293, 361 ; 
distribution, 645 
Ophiocephalus, 645 ; \abyrinthiform organ, 
293; O. marulius, 361; O. gachua, 
361 
Ophiodon, 696 ; O. elongatus, skull, 692 
Opisthocentrus, TOI 
Opisthognathus, G61 
Opisthomi, 776 f., 651, 306 
Opisthomyzon, GIL 
Opisthonema, 563 
Opisthoproctus soleatus, telescopic eyes, 
395 
Opisthopteryx, 611 
Opostomias, 571; O. micripnus, photo- 
phores, 178, 179, 181 
Opsanus, 711 
Opsariichthys, 582 
Oral hood, 116, 119, 186 
Oreinus, 582 
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