For many years numerous investigators have made efforts to establish a clinical syndrome for the recognition of lesions in the corpus callosum. Mingazzini,1from a study of personal cases and those reported in the literature, expressed the opinion that mental symptoms predominate with callosal lesions. Memory disturbances, especially for recent events, have been stressed by many investigators. Collier2expressed the belief that "mental reduction" was most constant with lesions involving the splenium. Niessl von Mayendorf3stated that disturbances of orientation may be due to interruption of the commissural fibers between the two occipital lobes, that is, to lesions of the posterior portion of the corpus callosum. Foix and Masson4observed disorientation in cases of thrombosis of the posterior cerebral arteries in which the splenium of the corpus callosum was destroyed. However, they could not form any conclusion as to the relative importance of the splenial lesion