Air which was injected into the ventricles through the two trephine holes (15), partially fills each lateral ventricle (areas of overlapping indicated by dense stipple in drawing), the third ventricle and the cerebral aqueduct. The third ventricle is clearly visible only because it is somewhat dilated. The positions of its various recesses and borders, however, are not displaced appreciably. An oval area (8), of greater density than the surrounding outline of the third ventricle, may represent the massa intermedia. However, the position of this area is somewhat anterior to the usual location for this structure.