Page:Natural History Review (1861).djvu/314

302 which is almost square In front, instead of being pointed, as in the ape. By adding on, as it were, a broad piece in front, the Simian brain would assume, in this aspect, a nearly human shape. But the posterior part of the hemispheres must, also, be somewhat lengthened and widened; and the lateral, or parietal, regions be likewise expanded. In this view, no trace of the cerebellum is visible at the sides, or behind, in either brain.

In the profile view, figs. 3 and 4, one is struck, in the Chimpanzee's cerebrum, as compared with man's, first, with its semi-globular shape; or rather, with its almost hemispherical outline above,—the vertex being comparatively low, and situated only a little behind the middle point, between its anterior and posterior extremities; the curve descending only a little more abruptly behind, than in front. In the human cerebrum, the vertex is extraordinarily high and is placed further back; so that the fall of the outline behind, is necessarily more sudden, and the depth of the posterior region is very characteristic. In the ape again, the shortness and shallowness of the anterior portion makes the curve of that part of the cerebrum more abrupt, and more equal to the hinder curve, than it is in man, in whom the elongated and deep, frontal region produces a much more gradual curvature from the vertex forwards, than exists backwards. The remaining points of contrast, in this aspect, are the singular, recurved, beak-like termination of the frontal lobe—its very deeply hollowed interior, or orbital surface—the great downward projection of the point of the so-called middle lobe—and the more marked obliquity and concavity of the lower border of the cerebrum from that lobe, upwards and backwards, in the Chimpanzee; as compared with the flatter orbital surface—less prominent middle lobe—and more nearly horizontal and straighter, lower border of the cerebrum behind that part, in man. In M. Gratiolet's side view, the hinder part of the cerebrum is a little more depressed, than it is in our specimen, and therefore a little less like the human shape. On this lateral aspect, the cerebellum of the Chimpanzee appears to bear about the same proportion, measured vertically and from before backward, to the cerebrum, as it does in man: though, in reality, these proportions of the cerebrum, are a little less in the ape, than in man, in whom the cerebellum looks rounder in profile. In the ape, the cerebellum is overlapped by the cerebrum, to the extent of $5⁄10$ths of an inch, and, in the human brain, by $6⁄10$ths of an inch, in other words, by about $1⁄9$th of the total length of the cerebrum in the Chimpanzee, and by only about $1⁄11$th of that measurement in man. So that the relative amount of overlapping is greater in the Chimpanzee. Lastly, in the ape, the direction of the medulla oblongata is a little more oblique, than it is in man. In M. Gratiolet's lateral view, the cerebellum, indicated in outline, is represented as too deep, and the direction given to the medulla oblongata is too nearly horizontal, so that the position of the cerebellum is not quite true: still, it is covered by the cerebrum. In our own photographic view, fig. 4, and in