The piece termed "occipital bone" represents the centrum and the neural arch of the occipital, or the first cranial vertebra; the haemal arch is completed by the triangular scapulae (pleurapophyses), and by the coracoid processes (haemapophyses). The clavicles are the haemapophyses of the atlas, but are displaced that they may assist in affording support to the enormously developed coraco-scapular appendages, the anterior or the thoracic extremities.