Malformations of a peculiar kind, are produced by great projection of the cerebral skull above and in front of the facial; or, as is more frequently the case, by its receding behind the face; the facial angle is consequently either too great or too small.

The base of the skull is sometimes pressed in, in a remarkable manner, by the cervical vertebrae. The skulls in which I have observed this deformity were large, and were those of persons who had suffered, very probably during foetal life, from a moderate degree of chronic hydrocephalus. The portion which encroached upon the cavity of the skull was, in all cases, very thin. The special conditions under which this malformation occurs are unknown.

Lastly, the skull becomes misshapen in various ways, from fracture, indentation, depression, etc.

The shape of the cavity generally corresponds with the external form of the skull, though it may be altered without any deviation from the natural appearance of the exterior. The inner table is sometimes, as in rickets, unusually smooth and polished; and, sometimes, the elevations and depressions are unusually marked. The elevations and some prominences, such as the clinoid processes, or the eminentia innominata, are occasionally developed into thorn-like, pointed processes, sharp ledges, or shapeless swellings. Sometimes, thorns of this kind are found at unusual places, such as the sella turcica, or on its pommel, on the basilar process, etc.

When deformities of this class occur in cases of hydrocephalus and hypertrophy of the brain, and especially when, at the same time, the subject of them is rickety, the condition of the sutures is peculiar. In a few cases the denticulations form long radiating processes, but generally they are wanting, and the sutures are a mere sinuous apposition of the bones. In hyperostosis of the skull, especially in cases of syphilitic induration, the sutures become changed into a similar "harmonia".