The body of the fornix has been cut away to expose the upper surface of the thalamus and the choroid plexus in the lateral ventricle. The continuity of choroid plexus from lateral ventricle to third ventricle through the foramen of Monro is now clearly visible. The cingulum has been exposed throughout much of its course by removal of the cortex of the gyrus cinguli. Its passage into the paraolfactory area is demonstrated. The anterior cerebral artery has been divided and its distal portion retracted upward. The pons has been to dissected to demonstrate the course within it of fibers (26) from the cerebral peduncle and to show the position of the brachium conjunctivum (24).