6i8 



INDEX 



N, 



N 



i acre : nacreous layer, 399 

 Nasal organ, see Olfactory organ 

 Naso-lacrymal duct, 186, 535 

 Naso-palatine canals, see Canals 

 Naso-pharynx, 512 

 Natural History, 2 

 Natural selection, 227 

 Nauplius, 384 

 Navicular bone, 504 

 Neck, 484 



Nemathelminthes, 412 

 Nematocyst, 300, 311, 317 

 Nephridiopore, 341 

 Nephridium, 146, 340, 406, 421, 



424, 466, 592 

 Nephrostome, 98, 145, 146, 340, 



424, 466 

 NEREIS : occurrence and general 



characters, 350; parapods and 



setae, 350-352 ;trochosphere larva, 



354 ; practical directions, ^59 

 Nerve-cells, 167, 303, 318 

 Nerve-collar, 342 

 Nerve-cord, ventral, 342, 379 

 Nerve-fibre, 167 

 Nerve-foramina, 495 ; and see Skull 



and Vertebral column 

 Nerve-ganglia, 162, 163, 164, 167, 



342, 379, 408 

 Nerve-plexus: brachial, 161, 532; 



cceliac, 533 ; sciatic or lumbo- 



sacral, 162, 532 



Nerve-roots, 163, 425, 461, 532 

 Nerves : afferent and efferent, 166, 



175 ; cerebral, 163, 461 532 ; 



of lateral line, 463; motor and 



sensory, 162, 169 ; phrenic, 532 ; 



sciatic, 62, 162, 532 ; spinal, 



160, 425, 461, 532 ; sympathetic, 



162, 461, 533 ; vaso-motor, 174 ; 



visceral, 380 



Nervous impulse, 62, 154 

 Nervous system : Frog, 155; Hydra, 



303 ; Obelia, 318 ; Earthworm., 



342 ; Crayfish, 379 ; Mussel ', 408; 



Lance let, 424 ; Dogfish, 458 ; 



Rabbit, 528 ; development of, in 



Vertebrates, 577, 584 



Neural arch, spine, and canal, see 

 Vertebra 



Neural plate and process, 440 



Neuraxis, 167 



Neurenteric canal, see Canal 



Neurilemma, 167 



Neuroccele, 459 ; and see Canal, 

 central of spinal cord, and Ven- 

 tricles of brain 



Neuroglia, 169 



Neuropod, 351 



Newt, 218 



Nictitating membrane, 5, 486 



Nodes of nerve-fibre, 167 



Nose, see Olfactory organ 



Nostrils, 5, 17, 180, 432, 464, 487, 

 534 



Notochord, 203, 419, 441, 578, 594 



Notopod, 351 



Nuclear division, 561, 603 ; in- 

 direct, 562 



Nuclear membrane, 559 ; spindle, 

 561 



Nucleolus, 109^ seq., 558, 559 



Nucleus, 106 et seq., 129, 231, 243, 

 254, 265, 269, 273, 280, 286, 558 



Nucleus, conjugation-, 268 ; seg- 

 mentation-, 571 



Nutrition, 67 ; and see under various 

 types 



O 



V_>/BELIA : occurrence and ge- 

 neral characters, 309 ; micro- 

 scopic structure, 311 ; structure 

 of medusa, 314 ; nervous system, 

 318 ; lithocysts, 315 ; reproduc- 

 tion and development, 320 ; 

 alternation of generations, 321 ; 

 practical directions, j^j 



Occipital condyle, see Skull 



Ocellus, see Eye-spot 



Odontoblasts, 445 ' 



Odontoid process, 499- 



CEsophagus, see Gullet 



Qisophageal glands, see Calciferous 

 glands 



Olecranon, 49, 502 



