Sensation was dull over the left side of the face, also over the left side of the neck. There was complete loss of cutaneous sensibility over the lower half of the forearm and hand, and a similar patch in the left axilla. Over the rest of the extremity the sensation was better on the flexor than on the extensor aspects. There was little alteration in the common sensation elsewhere, except that the contrast between that of the dorsum and sole of the foot was somewhat more marked than usual. The temperature of the insensitive axilla was one degree higher than that of the right. The left knee jerk was somewhat exaggerated. On December 15 an incision was made through the old cicatrix directly over the defect in the skull. On separating the skin it was found directly adherent to the cicatrised dura, and when this was incised a large vicarious arachnoid space was opened up. The space was crossed by a number of strands of connective tissue, and the cavity had no epithelial lining. The fluid ran out freely, and the space was evidently in free communication with the general arachnoid cavity. A trephine crown was taken out at the posterior end of the gutter, and the surface of the brain explored, but no fragments of bone were found. I therefore replaced the crown, and closed the bony defect in the floor of the gutter with a plate of platinum fitted into a groove made in the bony margin. The wound was then sutured. Primary union took place, and there was no constitutional disturbance beyond one temperature of 100 deg. on the evening of the second day; otherwise the temperature remained normal, and the pulse did not rise above 75. On the second evening a fit occurred, coming on while the patient was apparently asleep. It lasted about a quarter of an hour and was general, the patient becoming for a short time unconscious, and passing water involuntarily. On the third morning two similar fits occurred, the first a severe one, during which the patient passed a motion involuntarily. The commencement of all three fits was observed by the nurse only, but in each the convulsions apparently commenced in the face and then became general. Three months later no further fits had occurred, and the patient, who throughout had said he felt remarkably well, complained of nothing. The upper extremity was apparently slightly less rigid than before the exploration, and the patient said he walked somewhat better than before. The closure of the skull was perfect.