Among the gliomas of the temporal lobe a particular type of tumor has been encountered at operation. The tumors have usually been described as deep-seated, grayish and of firm consistency. Histologically they have proved to be fibrillary astrocytomas. These tumors have no definite demarcation from the adjacent nerve tissue and, in this respect, differ markedly from the cerebellar astrocytomas, which are fairly well demarcated and separable from the nerve tissue of their vicinity. At Dr. Cushing's suggestion a tabulation and investigation of these cases were made in order to determine whether their clinical symptomatology was not sufficiently characteristic to justify a preoperative histopathologic diagnosis.
The incidence of these tumors was comparatively small among a large series of gliomas of the temporal lobe. Only eleven cases were classified as fibrillary astrocytomas. The description of the growths is based on Dr. Cushing's operative notes and drawings. Although the majority of the patients