Previous descriptions of the heart in Hypogeophis rostratus have indicated the presence of a complete interatrial septum, and an atrio-ventricular muscular ring, the ventricle has been described as being almost completely divided into two cavities by a large ventricular trabecula. Further, it has been stated that the bases of the common carotid arteries cross within the truncus and that a spiral fold is present which divides the truncusinto a ventral chamber, which leads to the right carotid and the systemico-pulmonary arch, and a more dorsal chamber which leads into the left common carotid. The systemico-pulmonary arch is said to have a connection with the left carotid artery via a lateral dorsal aorta.