In calling attention to pneumatocele of the cranium I do so not with the idea of conveying some new or important information or advanced treatment, but rather to recall to mind a decided rarity, if we may judge from the few recorded cases, and to make easier, perhaps, the recognition of future cases. What I can at least offer is the record of an additional case and a thorough résumé of the literature, which I will present as briefly as possible, with a synopsis of all recorded cases. These number as yet but 33, of which 23 were occipital, 10 frontal. With a full bibliography added it will be an easy matter in the future to make reference to this subject. Patient. —A. C., aged 63, was admitted to the hospital May 26, 1902, and was operated on June 17, 1902. History. —Two years ago