INDEX 



Plica semilunaris, of human eye. 

 Fig. 101, 194; as vestige of 

 third eyelid, 194 



Pliocene, fossil human record a 

 blank during the, 70, 142; 

 reduction of human canine 

 teeth may have occurred dur- 

 ing the, 142 



Polyplocodus, teeth of. Fig. 18, 

 following, 30 



Polypterus, embryo of, Fig. 14, 26; 

 jaw muscles of. Fig. 61, 103; 

 representative of lobe-finned 

 ganoids, 24 



Postfrontal bone, eliminated by 

 time of earliest mammals, 88, 

 90 



Postorbital bone, joint process of 

 frontal and malar replace, 90; 

 eliminated by time of earliest 

 mammals, 88, 90; evolution 

 of. Fig. 51, 81 



Postsplenial bone, series of skulls 

 showing evolution of. Fig. 

 62, 82; reduction of, 88; of 

 Megalichthys, Fig. 64, 111; 

 of T rimer orhacliis. Fig. 64, 

 111 



Posture, its effect upon develop- 

 ment of face. Fig. 36, 59, 

 64, 66; characters of early 

 primates adapted to, 67, 

 68 



Prearticular bone, of Trimeror- 

 hachis. Fig. 64, 111 



Pre-chordates, eyes of, 186 



Predaceous habits, organization 

 of primitive vertebrates 

 adapted to, 101 



Prefrontal bone, evolution of. 

 Fig. 51, 81; eliminated by 

 time of earliest mammals, 

 88 



Premaxilla, evolution of. Fig. 50, 

 80; Fig. 53, 85; position of, 

 107; effect on shape of nose, 

 168; unites with maxilla in 

 anthropoids and man, 87; of 

 crossopt and early amphibian 

 are homologous, 107; of 

 Baphetes, Fig. 63, 108; of 

 Eusthenopteron, Fig. 63, 108; 

 covered with skin in early 

 amphibians and reptiles, 130; 

 origin of, in crpssopts^ 130 



Premolars, in primitive man, 76; 

 origin of, 90; of cynodonts, 

 116; of fossil man, 143; of 

 Dryopithecus, Sivapithecus, 

 Neanderthal and Homo 

 sapiens. Fig. 75, 144; front 

 lower, of anthropoids, 144; 

 nearest affinities of human, 

 144 

 Preoperculum, elimination of. Fig. 



17, 30, 114 

 Presphenoid bone, 167 

 Pre-vertebrates, see Chordates 

 Prevomer bones, evolution of. 

 Fig. 53, 85; of Devonian 

 crossopts, 100 

 Primates, mammals of Basal 

 Eocene of Montana approach 

 the, 53; family Notharctidte, 

 54; hind foot of, always of 

 tree-grasping type, 54; com- 

 parison of hands and feet of 

 fossil and recent, 54; arboreal 

 stage passed through by all, 

 54; skeleton of primitive fossil. 

 Fig. 32, facing 54; skull of 

 primitive fossil. Fig. 33, 55; 

 faces of lower. Fig. 34, facing 

 56; traces of insectivorous 

 dentition in, 57; ears of the 

 lower, 57; top view of skulls 

 of. Fig. 35, 58; side view of 

 skulls of. Fig. 36, 59; Epitome 

 of Fossil History of. Figs. 37, 

 38, 61, 62; value of study of 

 fossil and recent, 60; rare as 

 fossils, 60; relation of upper 

 jaws to eyes in, 60; Keith 

 cited on diaphragm, abdomen 

 and pelvic floor of, 63; pro- 

 gressive series presented by 

 brains of, 63; agreement of 

 results of studies on internal 

 and external anatomy and 

 fossil history of, 63; time of 

 assumption of human char- 

 acters of, 64; enlargement of 

 brain characteristic of. 64; 

 correlated use of eyes, hands 

 and feet in, 64; man derived 

 from Old World, 65; develop- 

 ment of eyes of, 65; char- 

 acters adapted to diet and 

 posture in, 67; characters of 

 man, and 67; man owes 



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