The experience gained in a hospital devoted to the treatment of diseases of the jaws, face and associated parts, demonstrated to me several years ago that the text-book descriptions of the anatomy of these parts did not correspond closely with numerous observed clinical facts. To clear up the contradictory elements of this subject, I began, some four years ago, to make serial sections of such skulls as I could gain possession of, in all, numbering some hundreds. These studies, some of which have been published, demonstrated that many of the printed, or text-book, description of the parts included, contained matter entirely at variance with observed facts. Finding these printed errors so numerous in the anatomy relating to the parts embraced in the field of oral surgery, it was natural to carry the observations to more distant parts, and I found in them, as will be shown, that errors of description