... there is one point which has delayed the right conception and understanding of the evolutionary process for a long time. This was the idea that the older the morphological age of the human form is, the more it must approach the living anthropoids. This conclusion did not take into account that the big apes, too, must have undergone essential changes during the same period of time in which man evolved. WEIDENREICH, Apes, Giants, and Man, Chicago, 1946, p. 11/12. CONTENTS Introduction . . . 175 Homo sapiens L. subsp . . . 182 Pongo pygmaeus palaeosumatrensis nov. subsp . . . 187 Incisors . . . 188 Canini . . . 199 Premolars . . . 208 Molars . . . 229 Milk dentition . . . 264 The prehistoric orang-utan population . . . 269 Pongo pygmaeus (Hoppius) subsp. from the Pleistocene of Java . . . 272 Pongo pygmaeus weidenreichi nov. subsp. from the Pleistocene of S. China . . . 280 Summary; the evolution of the dentition of Pongo pygmaeus (Hoppius) . . . 284 INTRODUCTION Man's natural interest in his nearest relatives has built up an enormous