INDEX 



Oronasal groove, see nasobuccal 

 groove 



Osborn, H. F., evidence for his 

 conclusions on ancestry of 

 placental mammals, 51; view 

 of separation of man and 

 apes from primitive stock, 74 



Ossicles, auditory, see Ear, audi- 

 tory ossicles 



OsteolepidsB (Crossopterygii) 

 closely related to Amphibia 

 of Carboniferous, 114 



Osteolepis (Devonian), skull of, 

 cross section. Fig. 9, facing 20; 

 seen from above. Fig. 11, fac- 

 ing 22; spiracular cleft in, 209 



Ostracoderms, probably ancestral 

 to cyclostomes, 186; a modern 

 descendant of the. Fig. 59, 97; 

 their use of cilia for ingestion, 

 95; ingestion transitional be- 

 tween ciliary and predacious, 

 97; origin of mouth jaws and 

 teeth uncertain below, 101; 

 mouth of, 129; denticles in 

 skin of, 117; teeth of 

 (Lanarkia), 117; Prof. Patten 

 on, 8; Stensio on cephalaspid 

 o., 94; Anaspida, characters 

 of the order, 96; Fig. 4, 11 

 Cepkalaspis, restoration of. Fig. 

 4, 11; restoration of head of. 

 Fig. 57, 95 

 Kiwraspis, restoration of head 



of. Fig. 57, 95 

 Lanarkia, shagreen denticles of, 



100 

 Pteraspis, restoration of. Fig. 4, 



11 

 Pterolepis nitidus, restoration 

 of. Fig. 4, 11, also Fig. 58, 96 



Otic capsule, as a component of 

 the chondrocranium, 83; of 

 shark. Fig. 7, 17, Fig. 81, 155 



Otic notch, in early amphibians, 

 29, 209, Fig. 17, 30 

 of Seyviouria, 32, Fig. 19, 33 

 in reptiles, 209 



Otoliths. 206 



Palceogyrinus, skull of, showing 

 loss of opercular series. Fig. 

 17, 30; side view of. Figs. 

 48-52, 78-82 



Palatal arches, reduction in size 



of teeth, factor in shortening 

 of, 143 

 of gibbon, female. Fig. 74, 140 

 of gorilla, male. Fig. 74, 140 

 of chimpanzee, female. Fig. 74, 



140 

 of orang, female. Fig. 74, 140 

 of Neanderthal man (Le Mous- 



tier). Fig. 74, 140 

 of modern white man, Fig. 74, 

 140 

 Palatal bone, 83 

 Palatal region 



of cynodonts. Fig. 52, 82 



ot Scymnognathus, ¥ig. 53,85, 118 



progressive changes in. Fig. 53, 



85, 118 

 of mammals. Fig. 53, 85, 119 

 in human embryo, 120 

 Palate, bony, its eflFect on shape 

 of nose, 169; comparative 

 anatomy of human, Fig. 66, 

 121; cleft, human, 228; cleft 

 palate, in Felis leo. Fig. 66, 

 121; fleshy, possible rudi- 

 ments in Scymnognathus, 119; 

 of lizard. Fig. 66, 121; 

 primitive, formation of, 122; 

 reptilian, 122; secondary, in 

 human embryo. Fig. 66, 162; 

 of cynodonts. Fig. 52, 119; 

 soft, of mammals, 119 

 Palatine bone, of cynodonts, 119 

 Palatoquadrate, 



of Devonian crossopts, 109 

 of Diadectes, Fig. 62, 105 

 of shark. Fig. 0, 13, 17, Fig. 7, 

 17, Fig. 8, 18, 106 

 Palatoquadrate cartilages, 102 

 Paleocene of New Mexico, early 



placental mammals in, 52 

 Pantotherian, dentition of. Fig. 



77, 147 

 Papillae vallatfe, of orang similar 



to those of man, 123 

 Papuans, noses of, 169 

 Paramcecium (Slipper animalcule), 

 face of, 4; mouth of. Fig. 1, 5 

 Parapineal eye. Fig. 97, 185; as 



directional organ, 200 

 Parapineal organ, origin of, 187; 



in pre-chordates, 186 

 Parapithents, lower jaw of P. 

 fraasi. Fig. 37, 61; left lower 

 molar of, Fig. 38, 62 



284 



