 Each nostril is roughly twice as long as the width of the mouth and extends along almost the entire leading margin of each blade.The circular eyes, located at the forward outer corners of the cephalofoil, are equipped with protective nictitating membranes.The relatively small, arched mouth contains 15–16 upper and 14 lower tooth rows on each side, and sometimes also a single row of tiny teeth at the upper and/or lower symphyses (jaw midpoints).