sentences:  The head is broad and dorsally flattened, with a rounded snout.The large, oval eyes have cat-like slit pupils, a rudimentary nictitating membrane (protective third eyelid), and a prominent ridge running underneath.A distinguishing trait of this genus are the large nostrils partially covered by greatly expanded, triangular flaps of skin that overlap the mouth and cover a pair of deep grooves between the nasal excurrent (outflow) openings and the mouth.