DEVELOPMENTAL STUDIES ON THE INTERPARIETAL PART OF THE HUMAN OCCIPITAL SQUAMA

The development of ossification centres in the membranous occipital sq uama is described, based on observations on human fetal skulls. The in terparietal part develops basically from 3 pairs, 1 primary pair and 2 secondary pairs; an additional 4th pair is occasionally observed. The so-called separated interparietal bones (Inca bones) are formed by a failure of fusion between the primary and secondary centres, not betwe en the supraoccipital and interparietal parts. The preinterparietal bo nes, which are developed from the additional 4th pair of interparietal ossification centres, are clearly differentiated from other anomalies in the lambda region by the shape of their territory and by their loc ation. The issue still remains as to how to establish their identity i n skulls from individuals of advanced age.