Estimated duration of the Cainozoic Period, assuming that the thickness of the deposits is about 63,000 feet, and that deposits accumulate at the rate of 1 foot in 100 years. Drawn to the scale of 1 mm. to 100,000 years. The estimate is given and explained by Prof. Sollas in the _Quarterly Journal of the Geological Society_, LXV. (1909). The “tree” is based on that given by Dr. A. Keith in _The Antiquity of Man_, p. 509. If we suppose the differentiation of the _Hominidæ_ to have begun before the close of the Oligocene, about (say) 3,500,000 years are allowed for the evolution of the existing species of Man. All these reckonings are provisional. [3] That Man was from the first a hunter has been suggested by several authors; but the consequences of the assumption have never (as far as I know) been worked out. A. R. Wallace, in _Darwinism_ (p. 459), has the following passage: “The anthropoid apes, as well as most of the monkey tribe, are essentially arboreal in their structure, whereas the great distinctive character of man is his special adaptation to terrestrial locomotion. We can hardly suppose, therefore, that he originated in a forest region, where fruits to be obtained by climbing are the chief vegetable food. It is more probable that he began his existence on the open plains on high plateaux of the temperate or subtropical zone, where the seeds of indigenous cereals, numerous herbivora, rodents, game-birds, with fishes and molluscs in the lakes and rivers and seas supplied him with an abundance of varied food. In such a region he would develop skill as a hunter, trapper or fisherman, and later as a herdsman and cultivator—a succession of which we find indications in the palæolithic and neolithic races of Europe.” Prof. MacBride, in his popular introduction to _Zoology_ (p. 84), also traces the specialisation of Man to the hunting life.