Cysts of the pituitary body have been recognized since Erdheim's1 studies of their cellular construction, but they have only been attacked in a surgical way during the past few years. Cushing,2 Jackson,3 and Lewis4 have perfected the operative technic for removing these cysts. They are of two types, the one originating from the hypothysial duct and the other from Rathke's5 pouch—a diverticulum of the embryonic buccal cavity from which the anterior lobe of the pituitary body develops. The latter are considered to be rudiments of embryonic development, in which the primary oral ectoderm has become misplaced. As the bones at the base of the skull develop, the attenuated oral end of this pouch atrophies, and the distal end becomes completely severed from the buccal end. They are called craniopharyngeal pouch cysts, extending upward and forward above the pituitary body, but beneath the optic chiasm.