A presentation of the lower extremities may generally be recognized at an early stage, by the head being felt at the _fundus_ of the Uterus, and by the pulsations of the fœtal heart being heard above the umbilicus, as explained in the section on Auscultation. After labor has commenced the part felt at the mouth of the Womb is irregular, and so different from the head, that it is not likely to be mistaken for it. If the knees or feet present, they can always be distinguished; and if the breech presents it can easily be recognized by its form, and particularly by the os coccygis, which can be distinctly felt at the bottom of the depression between the two cheeks. The side on which it is felt of course determines the position, and the same with the front of the knees, or the heels. The Rectum can also be reached with the finger, when the breech is touched; but great care must be taken not to intrude it too far, because with a female child the _Vulva_ might be mistaken for it, and thus the hymen be broken, and other injury committed. The genitals of a male child are more obvious, so that the sex of the child may be usually ascertained, along with the position. For want of proper care the breech has been mistaken for the head, and face, but this can scarcely happen if the accoucheur is attentive. It is simply necessary to call to mind what _must_ be felt in each presentation, as the _nose_ and _mouth_ with the face; the two cheeks of the posteriors, with the opening between them; and also the genitals, with the breech; and it can be certainly ascertained which of these parts are really at the opening. With the knees or feet there can scarcely be a doubt. DELIVERY IN A BREECH PRESENTATION IN THE LEFT ANTERIOR SACRO-ILIAC POSITION. In this position the legs and thighs are turned up against the abdomen, the breech in full occupying the passage, with the sacrum to the left and in front of the mother's pelvis. The descent of the breech usually takes place without much difficulty, into the Pelvis, it being small and easily compressed. It descends in the same direction in which it first presents--that is diagonally, like the head--and also rotates, or turns round, so that the left buttock comes in front, just to the right of the pubis, while the right one goes behind, to the left of the sacrum. The left buttock reaches the mouth of the Vulva first, in this position, and then remains stationary there while the right one slides along the curve of the sacrum and perineum, and passes out first at the lower part of the external opening. The left however, speedily follows, and when the whole breech is born it rotates again, one hip coming immediately in front, and the other going immediately behind. Owing to this movement the long diameter of the breech is adapted to the long diameter of the Pelvis, as in the case of the head. This will be evident from the following Plate:-- [Illustration: PLATE XXXII.