In each of these _three_ full presentations there may be certain variations, which require to be noticed. The head, for instance, may present either by the _cranium_ or by the _face_; the lower part of the body may present either by the _feet_, the _knees_, or the _breech_, according as the legs and thighs are flexed or extended; and the trunk may present either on the _right_ or _left_ side, and inclined towards the _back_ or towards the _chest_, though neither the back nor abdomen ever fully present. Each of these variations may also have slight variations again. Thus the face may present full, or by one or the other cheek, and so on. These variations however, are of little practical consequence, because we only find them at the very commencement of the labor, and they always change to the full presentation. Practically speaking therefore, there are _five full presentations_, viz., _the Cranium_, _the Face_, _the Breech_, _the Feet_, or knees, and the _Trunk_, either by the right or left side. The _varieties_ of these, as already remarked, not requiring any special attention from the accoucheur, providing he is not puzzled or misled by them. POSITIONS. The position means the particular direction in which the presenting part of the Fœtus is placed in relation to the Pelvic straits. The Pelvis itself is supposed to be divided into two similar halves, the _right_ and the _left_, and each presenting part has one particular place which is referred to as the indicating point. Thus, for instance, in the Cranium the Occipit, or behind part of the head, is the indicating point; and we therefore say, in Cranium presentations, that it is a _right or left Occipital position_, according as the back of the head is to the right or left side of the Pelvis. In face presentations, the chin (_mentor_) is the indicating point, and we therefore say it is a _right or left mento position_, according as the chin is towards the right or left side. In breech presentations, the child's sacrum is the indicating point, and we then say it is a _right or left sacral position_, according as the Sacrum is towards the right or left side of the Pelvis. In trunk presentations, which are always crosswise, the head (cephalo) is the indicating point, and we therefore say it is a _right or left cephalo position_, according as the head lies towards the right or left side of the mother's body.