556 



INDEX 



Crustacea, 227; of insects, 249; of 

 molluscs, 275, 282, 295, 296, 306; 

 of Nematoda, 152; of nemertean 

 worms, 148 ; of fluke-worm, 132 ; of 

 starfish, 162; of tape-worm, 149; of 

 vertebrates, 355, 380, 381. 



Nest, birds', 490. 



Neuroccele, 310. 



Neuropodiuin of annelid worms, 190. 



Newt, 432. 



Nictitating membrane, 408, 435, 492. 



Noctiluca miliaris, 41. 



Nodosaria, 25. 



Nomenclature, binomial, •*. 



Nostrils, in Apteryx, 486 ; of birds, 

 459 ; of frog, 408. 



Notochord, 310, 313, 324, 336, 337, 

 366, 406. 



Notochordal sheath, 325. 



Notopodium of annelid worms, 190. 



Nuclearia, 29. 



Nucleus, 16, 45. 



Nucula, 279. 



Nudibranch molluscs, 291, 296, 



Nummulites, 25. 



Nyctotherus, 49. 



Obelia, 99; commissuralis, 91 ; gela- 

 tinosa, 91 ; geniculata, 91. 



Ocelli, 104. 



Ocellus of insects, 250. 



Octopus, 302. 



Ocular plates of Echinoidea, 172. 



Odontoid process, 493. 



Odontophore, 293, 304. 



CEsophagus of starfish, 163; of in- 

 sects, 246. 



Oikomonas, 37. 



Oil glands ot birds, 459. 



Olfactory capsules, 410. 



Olfactory pit of Amphioxus, 328. 



Olfactory sacs of frogs, 425. 



Oligochseta, 202. 



Ommatidia, of Crustacea, 228 ; of 

 insects, 250. 



Omosternum, 415. 



Onychophora, 236. 



Oosperm, 59, 60, 62. 



Opalinopsis, 49. 



Operculum, 52; of bony fish, 396; of 

 Dipnoi, 407; of gastropod molluscs, 

 291,295; genital, of scorpion, 257 ; 

 of Limulus, 262; of Polyzoa, 181. 



Ophioglypba lacertosa, 169. 



Ophiuroidea, 169. 



Ophrydium, 53. 



Ophryodendron, 51. 



Ophryoglena, 49. 



Opisthocomus, 487. 



Opossum, 525, 528. 



Optic chiasma, 380. 



Optic lobes, 380, 480. 



Optic thalami, 354, 516; of sharks, 

 380. 



Orbito-sphenoid, 498. 



Organs, 66. 



Ornithorhynchus, 525, 527. 



Osculum, 77. 



Osphradium, 277, 295; in Nautilus, 

 308. 



Ossicles, ambulacra!, 161 ; auditory, 

 500; of starfish, 157, 



Ostium, 82. 



Ostrich, 483. 



Otaridse, 540. 



Otocysts, 98; of mussels, 277; of 

 Cephalopods, 308. 



Otoliths of vertebrates, 358. 



Otter, 526, 540. 



Ovaries, of birds, 482; of frog, 427,428; 

 of mammals, 520; of shark, 384; of 

 starfish, 107 ; of vertebrates, 359. 



Ovary, 101, 133; of Crustacea, 228. 



Oviducts, of birds, 482 ; of Crustacea, 

 229; of mammals, 520; of verte- 

 brates, 359, 428. 



Ovum, 59, 60; fertilization of, 61; 

 maturation of, 61 ; of mammals, 

 521 ; of vertebrates, 359, 384. 



Oxen, 526, 537. 



Oyster, pearl, 280. 



Pachychalina, 87. 



mesis in insects, 251. 



