Fig. 3. (A) Overhead view of a horn shark depicting the different locations that were stimulated by the dipole stimulus. (1) 5 cm in front of the anterior end of the shark, (2) right over the anterior end of the shark, (3) 2.5 cm posterior of the anterior end, (4) between the shark's eyes, (5) directly over the endolymphatic ducts, (6) 2.5 cm posterior of the endolymphatic duct pores, (7) 5 cm posterior of the endolymphatic duct pores, (8) 2.5 cm lateral of the endolymphatic duct pores, (9) 5 cm lateral of the endolymphatic duct pores, (10) 10 cm lateral of the endolymphatic duct pores, and (11) at the tail. The oval surrounding locations 5, 6 and 7 indicates the areas that yielded the strongest evoked potential from the dipole stimulus. Positions 5 and 6 are the location of the parietal fossa. (B,C) Evoked potential levels (mean ± s.d.) recorded from the horn shark and bamboo shark, respectively, at each location for 50, 100 and 200 Hz. Note that the closer the level obtained (in dBV) was to 0, the stronger the evoked potential that was recorded. 200 Hz yielded a weaker evoked potential in both species than 50 and 100 Hz, as it is the upper range of hearing in these species. Position numbers correspond to those in A.