"But it is sometimes the right ischium, which, in this chief division, is either originally turned forwards, or in the process of time assumes this direction. In this case the child passes through the pelvis in the same manner as before, only with the difference, that the surface of the body takes of course a different position with respect to the pelvic parietes, viz. its anterior surface, which in the former case corresponded to the right side of the pelvis, will be directed to the left, and the head will press through the superior aperture of the pelvis, in the direction of the left oblique diameter (the forehead passing before the left sacro-iliac synchondrosis.)" "As in positions of the cranium, the swelling of the integuments is chiefly met with on that parietal bone which during the passage of the head, is situated lowest, and on that spot with which it enters the external passage, so in this case the livid coloured swelling appears on that part which, directed forwards, was situated lowest during the passage of the nates, and with which the nates were born. "In the second chief position, viz. with the anterior surface of the child corresponding to the anterior abdominal parietes of the mother, it is chiefly the left ischium which is either originally situated forwards, or takes this direction as the nates sink through the superior aperture of the pelvis, which latter preserve this oblique direction during the farther progress of the labour, both whilst pressing into the pelvic cavity, and when entering the external passages. "If the ischia be already born, the anterior surface of the child turns itself to the right and backwards, either immediately, or as the rest of the trunk advances; but the manner in which the head in this case presses through the entrance cavity and outlet of the pelvis, is the same as has already been described." (Naegelé, _op. cit._ p. 128, 130.)