Since 1907 observations at autopsy of a thickened, rugose inner table in the frontal region of the calvarium has been to me a persistent challenge. There seemed to be no tradition concerning enostoses in the calvarium and no correlation with clinical observations. When the articles by Moore1and Carr2came to hand, nearly twenty-nine years later, I reviewed the protocols in the pathologic laboratory of the Massachusetts Department of Mental Diseases for the number of cases of enostoses of the inner table of the skull in that investigative service and found in the 3,250 records an incidence of 230, or 7 per cent. These changes, when extreme, consisted of irregular rolls of bony tissue, converging toward the nasal end of the (present or obliterated (metopic) suture. For the most part these bony masses were irregular and dense, the diploe being converted into tissue of ivory-like firmness. Now and