History. In January 1960, when the patient was years old, a large meningioma, weighing 250 gin. (Fig. 1) was removed from the suprachiasmal area. The tumor was located on the dorsal surface of the optic chiasma. The flattened optic nerves, chiasm and optic tracts were markedly stretched downward and bowing, resembling a small concave hammock in which the giant neoplasm nested. The meningioma was not attached to the basi]ar dura mater, the tuberculum sellae, the olfactory grooves, or the falx. Its blood supply was derived from the ethmoidal arteries. ~ The postoperative course was uneventful. He made a satisfactory recovery. Aside from a bilateral anosmia, all neurological findings were essentially normal including fundi and vision. Course. Sixteen months later seizures occurred, each attack lasting 2 to 5 minutes. During these seizures the child was stuporous but not unconscious, with eyes fixed, pupils dilated, pale, at times perspiring and hyperventilating without tonic or clonic phase. The seizures were largely controlled by Dilantin and 1Vfysoline. Since the operation the child was noted to be restless and hyperactive. He seemed to be everywhere at once, running and hopping, shifting from one activity to another, but short of concentration. He was constantly exploring and manipulating objects in the environment, not remaining with any one thing for any great length of time but moving about from one thing to another as if driven from within. Fits of anger were easily provoked. In tantrum, he rolled on the floor. At meals he was running in and out for a mouthful at a time. For this hyperkinetic behavior he was treated with Dexedrine 5 mg. t.i.d. The hyperactivity was reduced considerably. Repeated electroencephalography showed diffuse bilateral delta activity, especially prominent in the left frontotemporal region. Spike potentials often were intermixed with the slow activity. In December 1961, examination disclosed a bilateral weakness of the 6th cranial nerve, more marked on the left. There was no papiUedema. His fundiand vision were normal. Measurement of the head was normal for his age. All other neurological findings were essentially negative. A radiograph of the skull showed the cranial sutures to be normal. A globular shadow of calcification was visualized extending from the midline to the left (Fig. 2). Radiograms taken in 1960 before the first operation