As shown in the diagram on page 8, Fig. 1, the greatest length of the Neanderthal skull is found on the horizontal line directly through the brain chamber, known as the _glabella-inion line_, a line drawn from a prominence between the eyebrow ridges to a point at the back of the skull known as the external occipital protuberance, or inion. This is also the longest line in the skulls of Spy and of La Chapelle, as well as of the anthropoid apes,(56) but in the north Australian skull, Fig. 1, owing to the greater expansion of the upper part of the brain, the greatest length of the skull is at a point considerably above the _glabella-inion_ line. The median section of the skull of the chimpanzee, of the Neanderthal, and of the north Australian displays in a very striking manner the generalization made by Schwalbe, in 1901, that the Neanderthal skull is truly an intermediate or half-way form between that of the anthropoid apes and that of _Homo sapiens_. We observe in this illuminating section the growth of the dome of the skull, that is, the great brain-bearing cavity above the _glabella-inion_ line _g-i_, by noting the contrast in the length of the vertical line of the _cranial height_, as compared with the space below the _glabella-inion_ line indicated by the letters. This very important vertical line terminates below at the opening, where the spinal cord enters the base of the brain (see Fig. 1). [Illustration: FIG. 116. Top view of three skulls--of a chimpanzee (left), of the man of La Chapelle-aux-Saints (centre), and of a modern Frenchman (right)--showing the retreat of the projecting face and prominent eyebrow ridges. After Boule.]