THE METOPIC SUTURE.

At birth the frontal bone consists of two halves, separated by the interfrontal or metopic suture. Toward the end of the first or the beginning of the second year, this suture begins to close from below upward. In cases of premature closure before birth, the suture closes both from above and below toward the middle, and a marked cranial deformity ensues, known as trigonocephaly. As the name indicates, the skull is of a triangular shape, with the apex in front, so that the forehead runs out into a very sharp point. In the lower animals the frontal bone remains in two halves during life, but in the primates a single bone is the rule. Persistence of the frontal suture is known as metopism, and is found in various degrees. It may be, 1, entirely open; 2, open at both ends; 3, closed only at the lower end; 4, closed only