The material underlying this study was as follows: Forty adults and a larger number of pelves of newborn infants were dissected. Microscopic sections were made in various planes of the broad ligaments. Serial sections were made of these structures in fetuses of from three to six months, and also of pelvis of younger embryos. The whole clinical study is based on 46 cases operated on in the past four years. Works on anatomy are in accord in describing the broad ligament as formed of two layers of peritoneum. It is described in a recent work by my distinguished teacher, Waldeyer,1in a general way as composed of two serous layers, between which are vessels and nerves, many smooth muscle fibers and more or less connective tissue. This generally accepted opinion becomes questionable when it is considered that the peritoneum, strictly speaking, can be dissected from the pelvis complete, except