INDEX 



Notharctus (Eocene) — {Continued) 

 skull of, side view. Fig. 33, 55, 

 Fig. 36, 59, Fig. 48, 78; skull 

 of, top view. Fig. 35, 58 



Notochord, 21 



Nycticebus, external ear of, Fig. 

 110, 213 



Ocellus 



of fiatworm (Planaria), Fig. 2, 



facing 6 

 of jellyfish {Catablemd), Fig. 91, 



175 

 of jellyfish (Sarsia), Fig. 91, 175 

 of sand flea (Orchestia), Fig. 

 2, facing 6 

 Octopus, eyes of, 179 

 Oculomotor nerves, of chimpan- 

 zee, 198 

 Olfactory capsule, its place in the 

 skull structure, 83; in em- 

 bryonic development, 167; 

 the value of double, 156; 

 in human embryo, 162, Fig. 

 65, 120 

 of mammal-like reptiles, 158 

 of shark. Fig. 6, 13, 14, Fig. 7, 

 17, 122, 154, Fig. 81, 155 

 Olfactory chamber 



of early amphibia, 118 

 of Lemur, 58 

 of Notharctus, 196 

 of Notharctus osborni, 56 

 Olfactory membrane, function of 



the, 158 

 Olfactory nerve, course and func- 

 tion of the, 155 

 Olfactory nerve cells, as special- 

 ized cell of skin, 157 

 Olfactory pit, 



in human embryo, Fig. 65, 120 

 of shark, 122 

 Olfactory sac, 157 

 Olfactory sense organs, 155 

 Oligocene, lower, separation of 

 man from early anthropoids 

 in (Osborn), 74 

 Ontogenetic study of physiog- 

 nomy, 224 

 Opercular notch, eardrum formed 



in location of, 89 

 Opercular tract, elimination of 

 plates of, in early amphibia. 

 Fig. 17, 30, 114 

 Opossum, fossil {Eodelphis), 47; 



skull of, Fig. 48, 78; compared 



to that of Didelphys, Fig. 27, 



48 



Opossum, recent {Didelphys), most 



primitive marsupial of today, 



47; with young. Fig. 26, 



facing 46; jaw muscles of. 



Fig. 61, 103; skull compared 



with that of Eodelphis, Fig. 



27, 48; skull of. Fig. 28, 49 



Optic capsule, of shark. Fig. 7, 17 



Optic cups, formation of the. Fig. 



97, 185, 187; development of 



retina from, in vertebrates, 



181 



Optic nerve, description of the, 



188; function of the, 191; of 



Sepia, 180 



Optic pouch, of the jellyfish, 175 



Oral cartilage, of shark and 



embryo vertebrates, 102 

 Orang, pattern of papillae vallatse 

 similar to that in man, 123; 

 external ear of, Fig. 110, 213, 

 214; palatal arch of female. 

 Fig. 74, 140; lacrymal bone 

 of, 200; nose of, 169; skull of 

 young, front view. Fig. 102, 

 197; teeth, lower molar. Fig. 

 79, 150; tongue of, 123 

 "Orang type," of human ear. 

 Fig. 110, 213 

 Orbicularis oris muscle 



of anthropoid apes and man, 



133 

 of catarrhine monkeys, 56 

 Orbital axes 



of lemuroids. Fig. 35, 58, 196 

 of platyrrhine monkeys. Fig. 35, 



58, 196 

 of catarrhine monkeys. Fig. 35, 



58, 190 

 of anthropoids. Fig. 35, 58, 196 

 Orbits 



of advanced lemuroids, 60 

 of lower primates, 60 

 of orang, 169 



of Tarsius, Fig. 31, facing 53, 60 

 Orchestia (Sand-flea), Fig. 2, fac- 

 ing 6 

 Organ of Corti, the. Fig. 103, 



203, 204 

 Organs, lateral line, of fishes, 206 

 Organ, parapineal, 186; pineal, 186 

 Ornithorhynchus, mouth of, 131 



283 



