[Illustration: FIG. 65.—The human skull from the Chapelle-aux-Saints, now in the Museum of Natural History, Paris. One-third the size (linear) of nature. _a-b_ is a line drawn from a point above the brow ridges (_a_) to a point on the exterior of the skull corresponding to the inner attachment of the membrane called the “tentorium” which separates the cerebrum above from the cerebellum beneath it. The part of the skull above this line (or rather the horizontal plane, the edge of which it represents) is the cranial dome, and is in this skull comparatively shallow. Compare it with the same line and the cranial dome in Fig. 75 of a Reindeer Man, which agrees with a modern European skull in the greater height of the dome above the line _a-b_. The line drawn from the line _a-b_ to the point _e_ is the vertical line erected at the middle point of the line _a-b_. It gives the measure of the greatest height of the cranial dome. The line from _f_ similarly falls on to the point half-way between the line _e_ and the point _b_. It measures the height of the back part of the cranial dome. Compare these and the other lines in the other figures of human skulls and that of the chimpanzee (Fig. 81), which are all drawn to the same scale as this figure, namely, one-third the linear measurement. _c_ is the point on the top of the skull known as the “bregma”; it is the point where the frontal bone meets the two parietal bones. The line _c-a_ cuts off a curved area lying in front of it. This is “the frontal boss,” and the vertical line to _d_, drawn from its most prominent point to the line _a-c_, gives a very good measure of the amount of prominence and volume of the forehead. Compare this area and the line _d_ in the other skulls figured, especially in the well-developed skull of the Reindeer Man (Fig. 75) and in the chimpanzee’s skull. The reader is referred also in regard to these measurements to my _Kingdom of Man_ (Constable & Co.). Besides these lines of measurement, the reader should note the great brow ridges, the prominence of the whole face below the orbits (not merely of the teeth-sockets). Fig. 65 gives the actual state of the skull. In Fig. 80 the same skull is drawn as restored by Prof. Marcelin Boule.] XLI THE MOST ANCIENT MEN