=Uterus Septus.=--In this variety development has progressed so far that externally the uterus presents the normal appearance. The septum that divides the two ducts has, however, failed to disappear, and a divided uterus results. The septum may extend throughout the body of the uterus, or it may be less perfectly formed. Often one side of the uterus is better developed than the other (Fig. 178). =Malformation of the Vagina.=--Malformation of the vagina is frequently present with malformation of the uterus. The septum that divides Müller’s ducts may persist throughout the whole length of the vagina, forming a double vagina; or the septum may have partly disappeared, being present in various stages of perfection. In double vagina each orifice may be guarded by a distinct hymen. Sometimes one of the canals of a double vagina is much better developed than the other. The orifice of the poorly developed canal may be closed at its lower extremity, so that the malformation is never recognized by the woman or physician unless the closed canal becomes distended with blood or other secretion. A variety of vaginal cyst may be formed in this way. [Illustration: FIG. 178.--Uterus septus (Cruveilhier).] _Unilateral Vagina._--In this variety of malformation one of the ducts of Müller fails to develop at all. The condition always occurs with uterus unicornis. The vaginal canal is smaller than normal and may be situated to one side of the median line. _Absence of the vagina_ rarely occurs. There may be no sign whatever of this structure, or it may be represented by a fibrous cord. The external genitals may also be absent, or they may be well developed. If the uterus and ovaries are well developed, much trouble may arise from retention of menstrual blood. An attempt should be made, by means of a transverse incision between the rectum and the urethra, to reach the cervix, and, if possible, to make an artificial vagina by transposition of skin from the buttocks. Such treatment is usually unsatisfactory, as a patulous canal cannot be maintained. It may be necessary to remove the uterus and appendages. Sometimes the vagina is absent in only part of its course, being open below and represented above by a fibrous cord; or the upper and lower portions may be developed, while the middle portion is imperforate. [Illustration: FIG. 179.--Transverse septum of the vagina (Heyder).] These conditions are more amenable to operative treatment than in the case of complete absence of the vagina. The intervening septum should be incised, and the patulous condition maintained by the passage of bougies if necessary. Sometimes the lumen of the vagina is obstructed by the presence of transverse bands or crescentic folds, which have been described as supplementary hymens (Fig. 179). A _hematocolpos_ is produced when the vagina becomes distended with menstrual blood above such an obstruction.