More and more tumors within the cranial chamber which hitherto have been considered inaccessible or inoperable are being radically attacked. Trying experiences with such a tumor—a chordoblastoma of the basilar plate—seem worth reporting, together with the pathologic study of a case of ecchordosis physaliphora spheno-occipitalis. Hints regarding the clinical diagnosis of both types of tumor and suggestions thought likely to facilitate and aid others to improve the operative procedure used are based on these experiences and on others recorded in the literature. The term chordoma is used to cover both types of tumor. REPORT OF CASES Case 1. —Chorodoblastoma of the basilar plate. History. —L. W., a medical student, aged 29, was first seen in the surgical division on May 18, 1933. His complaints were diplopia, partial weakness of the right internal rectus muscle, a sense of pressure in the head on changing position and numbness of the center of