The basi-occipital, a part of the "basilar process" of the occipital bone, is developed as a distinct piece from the basi-sphenoid in front, and from the ex-occipitals on either side. Superiorly it is concave from side to side, and receives the cranial prolongation of the myelon, or spinal chord. The exocci-pitals (neurapophyses) form the lateral boundaries of the foramen magnum, and are surmounted by the expanded neural spine, which, concave internally, is marked by four fossse, the two superior for the posterior lobes of the backwardly extended cerebrum: the two inferior for the lateral lobes of the cerebellum. This expanded neural spine is formed from four centres of ossification, which unite at that prominent portion of the bone known as the occipital protuberance. Its superior border is prolonged forwards, as a projecting angle, between the two parietal bones, in the same way as the supra-occipital bone in the codfish is inserted between the parietals, and prolonged so as to articulate with the frontal bone. The rough ridge of bone extending outwards from the condyles, and called the jugular process, originally united to the basi-occi-pital by cartilage only, is the homologue of the paroccipital bone in the cod, turtle, etc, and is to be regarded as the parapophysis. There is a preparation in the museum of St. Bartholomew's Hospital, showing how closely the long transverse process of the atlas corresponds both in size and form with the parapophysial element of the occipital vertebra: between these two processes extends the rectus capitis lateralis muscle, a repetition, in serial homology, of the intertransversales muscles in the neck, and of the intercostales in the thorax. Between the basi-occipital and the paroccipital is the anterior condyloid foramen, which transmits the hypoglossal nerve.