The appearance of the brain, divested of its membranes, when we look upon its superior surface, is shown in the annexed engraving, in which it is presented as it lies in the head when the cranium and membranes are removed which form the rim of the figure. The front lobe is the upper portion, and the outline of the nose is just visible. In the full exposition of this subject hereafter in a larger work, I propose to show the exact seats of the various functions in the convolutions, which are much more irregular than the angular figures we make on the surface of the head to show the average positions of organs. Of course no intelligent person supposes the psychological maps and busts of the organs to be representations of the brain, or anything more than approximations to the true interior organology, which, however, do not lead to any great error, as adjacent portions of convolutions have very analogous functions. [Illustration] When we place the brain on its upper surface and inspect the bottom, we observe at the back the cerebellum, which dips into the neck, the middle lobe, which is over the ears and the side face, and the front lobe, which rests over the eyes. We observe posteriorly the medulla oblongata, on the face of which we may observe the crossing of the fibres, and on the side of which we observe the origins of many nerves. Above the medulla we observe the pons Varolii, just above which we observe the fibres ascending to each hemisphere under the name of _crus cerebri_, or thigh of the cerebrum. Next we see the optic nerves crossing on the median line, the olfactory nerve, running under the front lobe, which is separated by the fissure of Sylvius from the middle lobe. There is also a glimpse of the corpus callosum at its anterior end, obtained by pulling the front lobes apart at the median line. [Illustration] Let us next cut through the head exactly on the median line, dividing the right and left hemispheres, and look at the inner face of the right hemisphere. We observe that it has convolutions, just like the exterior surface, which do not join across the median line, but are separated from those of the left hemisphere by a firm membrane (an extension of the dura mater or principal investing membrane) called the falx, which is removed, leaving the convolutions in view. The reader will observe that it is only in the lower portion of the engraving that he sees any surfaces produced by cutting to separate the right and left halves of the brain. It is by these structures which are here divided that the right and left halves are connected, so that the whole brain is adapted to acting in a unitary manner.