A microcephalous boy was born of healthy parents--he was their first child--about four weeks too soon. His whole body had something of stiffness and awkwardness. The legs were worse off in this respect than the arms; they showed, as they continued to show up to the time of his death, a tendency to become crossed. The boy was never able to stand or walk. He made attempts to seize striking objects, white or party-colored, but never learned actually to hold anything. The play of feature was animated. The dark eyes, shining and rapidly moving, never lingered long upon one and the same object. The child was much inclined to bite, and always bit very sharply. Mentally there was pronounced imbecility. In spite of his four years the boy never got so far as to produce any articulate sounds whatever. Even simple words like "papa" and "mamma" were beyond his ability. His desire for anything was expressed in inarticulate and not specially expressive tones. His sleep was short and light; he often lay whole nights through with open eyes. He seldom shed tears; his discomfort was manifested chiefly by shrill screaming. He died of pulmonary paralysis at the end of the fourth year. The autopsy showed that the frontal lobes were surprisingly small, and that there was a partial deficiency of the median longitudinal fissure. The fissure did not begin till beyond the crown of the head, in the region of the occiput. The anterior half of the cerebrum consequently lacked the division into lateral hemispheres. It had few convolutions also, and the smoothness of its surface was at once obvious. The _corpus callosum_ and the _fornix_ were undeveloped. "The gray cortical layer attained in general only about a third of the normal thickness, and was especially weakly represented in the frontal region." The cerebellum not being stunted, seemed, by the side of the greatly shrunken cerebrum, surprisingly large. In this case the microcephalous of four years behaves, as far as the development of will is concerned, like the normal boy of four months. The latter is, in fact, superior to him in _seizing_, while the former in no way manifests any advantage in a psychical point of view. Two cases of microcephaly have been described by Fletcher Beach (in the "Transactions of the International Medical Congress," London, 1881, iii, 615-626).