Evidence afforded by comparative studies on the brains of primates shows the anthropoid apes to be man''s nearest known relatives, the order of structural relationship being modern man; primitive man; gorilla; chimpanzee; orang; gibbon; Old World monkey; New World monkey; Tarsius; lemur; and pentailed tree-shrew. Modern students are also convinced that the general order of evolution was the reverse of this. Evidence afforded by the comparative study of the teeth of all known recent and fossil Primates shows the order of structural evolution to be: generalized tree-shrew (cf. Indrodon, Paleocene); primitive lemuroid (cf. Pelycodus ralstoni, Lower Eocene); primitive tarsioid (Parapithecus, Lower Oligocene); proto-anthropoid (Propliopithecus, Lower Oligocene); primitive anthropoid (Dryopithecus rhenanus); primitive man (Eoanthropus); and modern man (Homo sapiens europaeus). Among existing Primates the general order of resemblance to man in the dentition is: chimpanzee; orang; gorilla; gibbon; and Tarsius. Known remains of fossil anthropoids are sufficient to establish a high degree of probability that the separation of man from the anthropoid stock did not occur before the middle of the Tertiary. Assuming 12 years or about 8 generations to a century as the average rate, that would give 800,000 generations as the transitional period between Dryopithecus and the Piltdown man, during which much might be done toward bridging the remaining gap between some member of the Dryopithecus group and man, especially in view of the relatively high structural variability of all the known races of man and of anthropoid apes.