The fœtal head is ovoidal in form, the large extremity being posterior. Several bones enter into the formation of the cranium; they are, 1st, the _frontal_ bone forming the forehead; in the fœtus even at term it is usually divided; 2d, the two _parietal_ bones, one on each side of the head, meeting on the median line at the top of the head; they help to form the vault of the cranium; 3d, the occipital bone, forming the posterior and part of the base of the skull; and 4th, the temporal bones, one on the right and one on the left side below the parietal, completing the lateral portions of the cranium and contributing to form the base of it. The cranial bones are not united to each other by sutures as they are in the adult, but are separated, the parietal bones especially, by membranous intervals, the intervals being larger in some children than in others. These intervals, or _sutures_ and _fontanelles_, must be carefully studied. The _sagittal suture_ is the antero-posterior one, and extends from the root of the nose to the occipital bone. It is formed in front by the interval that separates the frontal bone into two halves, and superiorly by that between the two parietals. There is a suture which crosses this, called the transverse or _coronal suture_, which is formed by the space existing between the frontal and parietal bones. When the sagittal suture arrives at the superior angle of the occipital bone, it seems to part and give rise to two oblique lateral sutures which are called _lambdoidal_; these are formed by the posterior borders of the parietal bones and the superior one of the occipital. Just at the point where the coronal and the lambdoidal sutures join the sagittal one, two membranous spaces, larger than those just described, are found; these have received the name of _fontanelles_. In cases of head presentation during labor, one or the other of the fontanelles may be felt by the attending practitioner, and this indicates to him the position of the head and the presentation. The _anterior fontanelle_ presents an extensive surface at the place where the transverse crosses the sagittal suture. It is lozenge-shaped, and is bounded by four bony angles. The _posterior fontanelle_ is formed by the union of the two lambdoidal sutures with the termination of the sagittal suture. It is smaller than the anterior one, and is of a triangular form. It is bounded by the occipital bone and the angles of the parietal bones. During labor the bones may overlap each other so that the sutures cannot be felt, but the prominences of the bony margins will aid the diagnosis. THE PHYSIOLOGY OF FŒTAL LIFE.