Page:Evidence as to Man's Place in Nature.djvu/102

Fig. 17—Sections of the skulls of Man and various Apes, drawn so as to give the cerebral cavity the same length in each case, thereby displaying the varying proportions of the facial bones. The line b indicates the plane of the tentorium, which separates the cerebrum from the cerebellum; d, the axis of the occipital outlet of the skull. The extent of the cerebral cavity behind c, which is a perpendicular erected on b at the point where the tentorium is attached posteriorly, indicates the degree to which the cerebrum overlaps the cerebellum—the space occupied by which is roughly indicated by the dark shading. In comparing these diagrams, it must be recollected, that figures on so small a scale as these simply exemplify the statements in the text, the proof of which is to be found in the objects themselves.