In an earlier paper in this journal, we have described a method for measuring the maternal pelvis by means of true dimensional tracings or orthograms that portray the mid-sagittal plane and the inlet, mid-pelvis, and outlet. For obstetrical hospitals or other institutions having a good deal of pelvimetry to do, the objective precision of the orthographic method is desirable and the cost not prohibitive; but in other situations, where the volume of work does not warrant the purchase of a 90° table and a pantograph, equally precise work may be done with simple inexpensive apparatus, provided the radiologist exercises skill and care in making and working up the roentgenographs. The present paper is concerned with the clinical and roentgenological findings in 912 primiparous white women who were studied throughout pregnancy, including delivery. It had been our hope to report on an even thousand but 88 records had to be excluded, in most instances because the patient could not be followed through delivery. The work was done at the Chicago Lying-In Hospital of The University of Chicago, with the aid of Dr. M. E. Davis and presently will be published in detail in the obstetrical literature. Clinical Data All of the patients were examined with particular care by our obstetrical colleague, a special record sheet being employed for listing normal and instrumental pelvimetry, a clinical estimate of the adequacy of the pelvis, the course and outcome of the labor, and the condition, weight, and degree of head moulding in the newborn infant. The labors were classified as short (less than twelve hours), medium (less than twenty-four hours), long (more than twenty-four hours), and section. It had been planned to include caliper measurement of the fetal skull, but after the first few cases it was found preferable to substitute x-ray measurement during the first twenty-four hours of life—not only of the skull but of the trunk and extremities as well. In another publication we will weigh the relationship between pelvic dimensions and the ease or difficulty of labor against the dimensions of the fetus. The work-up of these data is not yet complete, but it is our impression that easy labor with small pelvic dimensions and difficult labor with pelvic diameters well above average are not the result of a small baby in the first instance or of a large one in the second instance. Dimensions and Indices We have measured numerous pelvic diameters and computed numerous indices based on them. Of these, six diameters and three indices are presented in the accompanying tabular material. The reference points for these diameters and the nature of the indices are as follows: Pelvic Inlet Anteroposterior Diameter: The anterior end-point of this diameter is that point on the posterior surface of the pubic symphysis that lies nearest to the sacrum, and the posterior end-point is that point on the anterior surface of the sacrum that lies nearest to the pubis.