The development of the neurocranium of the intermediate stages of Corvus has been studied . The metotic cartilage develops from two centers of chondrification, lateral and medial anlagen. Fusion of cochlear and canalicular portions of the auditory capsule takes place. The intertrabecular bar extends dorsally to form the rudiments of the nasal and interorbital septa. The hypophyseal incisura coverts into a hypophyseal fenestra. The paranasal cartilage has an isolated center of chondrification. The parietotectal cartilage develops from the dorsal edge of the nasal septum. It shares with the paranasal cartilage in the formation of paries lateralis nasi. The primary anlagen of the atrioturbinal cartilage and maxilloturbinal cartilage have the same center of chondrification (the parietotectal cartilage). The planum antorbitale and its processes are developed . The parietotectal cartilage gives the sphenethmoid commissure to connect with the anterior orbital cartilage. The promontorium is developed . The formation of fenestra ovalis and foramen perilymphaticum begins at these stages. The tectum synoticum starts to develop by the fusion of two prominentiae semicirculares anterior, and thus it is otic in origin