When the augmentation of the volume of the cranium is caused by an abundant quantity of serous fluid the anomaly is known as hydrocephaly. In this condition there is usually no change in the size of the brain-structure itself, but often the cranial bones are rent far asunder. Minot speaks of a hydrocephalic infant whose head measured 27 1/2 inches in circumference; Bright describes one whose head measured 32 inches; and Klein, one 43 inches. Figure 93 represents a child of six whose head circumference was 36 inches. Figure 94 shows a hydrocephalic adult who was exhibited through this country. There is a record of a curious monster born of healthy half-caste African parents. The deformity was caused by a deficiency of osseous material of the bones of the head. There was considerable arrest of development of the parietal, temporal, and superior maxillary bones, in consequence of which a very small amount of the cerebral substance could be protected by the membranous expansion of the cranial centers. The inferior maxilla and the frontal bone were both perfect; the ears were well developed and the tongue strong and active; the nostrils were imperforate and there was no roof to the mouth nor floor to the nares. The eyes were curiously free from eyelashes, eyelids, or brows. The cornea threatened to slough. There was double harelip on the left side; the second and third fingers of both hands were webbed for their whole length; the right foot wanted the distal phalanx of the great toe and the left foot was clubbed and drawn inward. The child swallowed when fed from a spoon, appeared to hear, but exhibited no sense of light. It died shortly after the accompanying sketch was made. Occasionally a deficiency in the osseous material of the cranium or an abnormal dilatation of the fontanelles gives rise to a hernia of the meninges, which, if accompanied by cerebrospinal fluid in any quantity, causes a large and peculiarly shaped tumor called meningocele. If there is a protrusion of brain-substance itself, a condition known as hernia cerebri results.