INDEX 



327 



Neural tube, 230, 238; cells of, 229-230, 

 238 



Neurilemma, 238 



Neurocoele, 230 



Neurogleal cell, 230 



Neuromast, 262, 275, 278 



Neurone, 229 



Neuropore, 230, 239 



Nictitating membrane, 5, 102, 266; ab- 

 sent in Heptanchus, 5; development of, 

 266 ; muscles of, 102-103 



Nictitator muscle, 102, 103 



Nitrogenous waste matter, removal of, 289, 

 296, 298 



Notidanids, 3, 6, 71, 264; auditory re- 

 gion of, 58 



Notochord, 47, 70; constructions, 47-48; 

 relation of, to spinal column, 47, 70; 

 section through, 48, 70; sheath of, 47, 

 70 



Notochordal sheath, 48, 70, 75; zones of, 

 48, 70 



Xotorhynchus (Hepfanchus), 3 note 



Nutrient arteries, 180 



Nutrient vein, 205, 207 



Occipital condyle, 57; in rays, 57 



Occipital crest, 43 



Occipitospinales nerves, 71, 227, 245-246 



Oculomotor nerve, 222, 223, 234, 239; 

 division to eye muscles, 239-240; fora- 

 men of, 44; ganglion of, 240; muscles 

 supplied by, 100; origin of, 239 



Odontoblasts, 30, 33, 34, 130 



Oesophagus, 123, 134; cells of, 134; folds 

 of, 123; lining of, 123, 134 



Olfactory bulbs, 223, 239, 258, 264 



Olfactory bundle. See Olfactory nerve 



Olfactory capsule, 43, 53, 57, 238; in em- 

 bryo, 53-55; in Zygaena, 55 



Olfactory cells, 264 



Olfactory fila, 239 



Olfactory lobe of brain, 223, 239, 258, 264 



Olfactory membrane, 239, 258, 265 



Olfactory nerve, 223, 238-239, 258, 264, 

 265 



Olfactory organ, 258, 264-265 ; circulation 

 in, 265; divisions of, 264-265; func- 

 tion of, 265; nerves of, 264 



Olfactory receptors, 258 



Olfactory sac, 264 



Olfactory tract, 221, 223, 239, 258, 264 



Omentum, 121 



Omphalomesenteric vein, 212 



Oocyte, 303; primary, 303; secondary, 

 303 



Oogonium, 303 



Ootid, 303 



Ophthalniica magna artery, 165, 181 



Ophthalmicus profundus (V), 223, 241; 

 ganglion of, 240-241; origin of, 240; 

 sensory fibers, 240 



Ophthalmicus superficialis (V), 223, 240, 

 241; ganglion of, 240, 241; origin of, 

 240; sensory fibers, 240 



Ophthalmicus superficialis (VII), 224, 

 242 



Optic artery, 183 



Optic chiasma, 221, 223, 239 



Optic cup, 269 



Optic lobes, 221 



Optic nerve, 221, 234; origin of, 239, 269; 

 relation of, to sclera, 268; termination 

 of, 234, 239 



Optic organ. See Eye 



Optic pedicel, 60, 90, 268; function of, 

 258 



Optic stalk, 269 



Optic thalamus, 236 



Optic vesicles, 230, 269 



Orbit, 53, 55, 60, 89; in Heptanehus. 5, 44; 

 muscle attachment to, 89 



Orbital artery, 182 



Orbital fissure, 44, 60 ; in embryo, 60 ; re- 

 duced, in Mustelus, 60 



Orbital process, 44, 62 ; in embryo, 62 



Orbital sinus, veins to, 198, 204, 205 



Orbitonasal canal, 44 



Organ of special sense, 258, 264 



Oronasal groove, 122 



Otolith, 272 



Outer buccal ampullae, 262, 279 



Outer (heavy) layer of retina, 268 



Ova, 290, 303 



Ovary, 290, 303; development of, 303 



Oviducal artery, 169, 193; anterior, 193; 

 posterior, 193 



Oviducal funnel, 290, 304 



Oviducal valve, 306 



Oviducal vein, 209 



Oviduct, 290, 304; arteries to, 169, 191, 

 193; development of, from Wolffian 

 duct, 304; divisions of, 304; rudimen- 

 tary, in male Heptanchus, 291, 309 



Oviparous, 307 



Paired fins, muscles of, 94, 109; origin of, 

 14-16; skeleton of, 50 



