Malacosteon or softening of the bones, may come on at any period of life, and frequently occurs without any serious constitutional disturbance. It consists in a gradual absorption from the bones of all their solid matter, so that they become soft, and may be bent or twisted like horn. Sometimes this state will be reached very soon, but at other times the disease progresses very slowly. The causes of it are unknown, and it is incurable. I have seen a patient who could bend the bone of her leg _nearly double_, as if it were a piece of rope. In my work on the Diseases of Woman, I have spoken upon various other causes which may deform the bones in young females, such as wearing corsets, improper attitudes in sitting, and want of sufficient _unconstrained_ exertion of the body in the open air. The deformities may be of various kinds, and may either alter the general appearance and the walk, or may not be discoverable except on examination. Sometimes the pelvis is _too large_, so that the womb and other parts are continually falling down into its cavity, but this is very rarely seen; more frequently it is either too small, or irregular in its form. In all cases where the irregularity in form, or diminution in size, is such as to prevent the passage of the child an operation becomes necessary, either upon the mother or her infant, and great danger is consequently incurred by both. It is therefore the duty of every mother, if she has the slightest suspicion that her daughter is deformed, though it may not be apparent, to have her examined before she is allowed to marry. _Many have lost their lives for want of this precaution._ Severe blows or falls in early life may also create a pelvic deformity, and this, as a possible consequence of such accidents, should always be borne in mind. The means by which the form and size of the pelvis are ascertained, as before stated, are simple, and such as need not in any way be feared. To enumerate all the varieties of deformed pelvis, as described by different authors, is unnecessary, and would not be useful here. I shall therefore only refer to them generally. Sometimes the pelvis is regular enough in its form, but singularly small altogether, not larger perhaps than that of a child eight or nine years of age. More frequently, however one part only is small, while the others are full sized, or the different parts are not in a proper position in regard to each other. Thus sometimes the pubic bones will be flattened backward, near to the sacrum, so as to narrow the antero posterior diameter of the upper strait; at other times one of the sides will be flattened towards the other, as if crushed in, and thus diminish all the diameters; and at other times one side will sink down lower than the other, and thus effect similar changes in another way.