[Illustration: THE FŒTAL HEAD. Plate XXIV. The head is generally divided into the Cranium, or that part which contains the brain, and the Face.] The bones of the cranium are not closed together, as they are in the adult, but are separated to a considerable distance, in certain parts, and connected by a strong membrane. These membranous spaces are called _Sutures_ and _Fontanelles_, and a knowledge of them is absolutely necessary, as a means of ascertaining the position of the head. _The Sutures._--The first of these spaces, which extends from the lowest part of the middle of the forehead to the occipital bone, is called the _Sagittal Suture_, or antero posterior Suture: A, B, C, Figs. 1 and 2. It separates the two frontal, and the two parietal bones. The spaces between the two frontal and the two parietal bones are called the _Frontal Parietal Sutures_, _o. o._ Fig. 1; and those between the two parietal bones and the occipital, _l. l._ Figs. 1 and 2, are called the _Lambdoidal Sutures_. _The Fontanelles._--When the different Sutures meet at a point, the membranous space is greater than at other parts, and is called a Fontanelle. Thus when the two Frontal Parietal Sutures meet the Sagittal Suture, at B, Figs. 1 and 2, there is quite a large diamond shaped space between the different bones, filled up with membrane. This is called the _Anterior Fontanelle_, or bregma. Where the Sagittal Suture joins the two Lambdoidal there is another space, not so large, and different in shape, being triangular; this is called the _Posterior Fontanelle_, _c._ Figs. 1 and 2. And where each of the temporal bones joins the parietal there are two other spaces, called the _Temporal Fontanelles_, _t._ Fig. 2, which are also irregularly diamond shaped, but not nearly so large as the anterior fontanelle. It is evident that if a person can distinguish these Fontanelles, when he touches them with his finger, he can tell what part of the head is presenting, and hence their use. These spaces allow of the bones lapping over each other, during delivery, and thus the head is made smaller. They do not disappear till sometime after birth, and in very young children the brain may be felt, and seen to work, at the anterior fontanelle. Eventually however, the bones come close together, and are joined by a curious kind of dovetailing. The two frontal bones however, completely coalesce, and form but one, in the adult. Sometimes the bones will be very perfectly formed, and the fontanelles nearly filled up, before birth, and then the head cannot be crushed much smaller, and so the labor becomes both painful and difficult. This is usually called an ossified, or solid head. _Diameters of the Head._--The diameters of the head are the distances between its most prominent points. They are necessary to be known before we can judge as to the possibility of its passing the straits of the Pelvis, in the various positions.