Mr. _A. H. Keane's Man Past and Present_[50] is a part fulfillment of a promise held out in his Ethnology, the first volume of the Cambridge Geographical Series, that it might be followed by another dealing more systematically with the primary divisions of mankind. In it the "four varietal divisions" of man over the globe are treated more in detail, with the primary view of establishing their independent specialization in their several geographical zones, and of elucidating the difficult questions associated with the origins and interrelations of the chief subgroups. The work consequently deals to a large extent with the prehistoric period, when the peoples had already been fully constituted in their primeval homes and had begun their subsequent developments and migratory movements. The author has further sought to elucidate those general principles which are concerned with the psychic unity, the social institutions, and religious ideas of primitive and later peoples. The two principles, already insisted upon in the Ethnology, of the specific unity of all existing varieties of the human family and the dispersion of their generalized precursors over the whole world in Pleistocene times are borne in view throughout. Subsequent to this dispersion, the four primary divisions of man have each had its Pleistocene ancestor, from whom each has sprung independently and divergently by continuous adaptation to their several environments. Great light is believed to have been thrown on the character of the earliest men by the discovery of the _Pithecanthropus erectus_, and this is supplemented as to the earliest acquirements by Dr. Noetling's discovery, in 1894, of the works of Pliocene man in upper Burmah. The deductions made from these discoveries strengthen the view Mr. Keane has always advocated, that man began to spread over the globe after he had acquired the erect posture, but while in other physical and in mental respects he still did not greatly differ from his nearest of kin. As to the age when this development was taking place, agreement is expressed with Major Powell's remark that the natural history of early man becomes more and more a geological and not merely an anthropological problem. The human varieties are shown to be, like other species, the outcome of their environments, and all sudden changes of those environments are disastrous. In both hemispheres the isocultural bands follow the isothermal lines in all their deflections--temperate regions being favorable, and tropical and severe ones unfavorable, to development. Of the metal ages, the existence of a true copper age has been placed beyond reasonable doubt. The passage from one metal to another was slow and progressive. In art the earliest drawings were natural and vital. The apparent inferiority of the drawings of the metal period to those of the cave dwellers and of the present Bushmen is due to the later art having been reduced to conventions. The development of