Iodine stained specimens of E. maculatus with swim bladder extensions and inner ears exposed. Lateral views (A-B) show the close vicinity of the swim bladder pad and the posterior and horizontal semicircular canals. In the ventral view (C), the swim bladder extension of the right side indicates the contact between the gas-filled part of the extension and the lagena. On the left side, the extension was detached exposing a ‘tissue sheath’ (‘pad’) closing the exoccipital foramen, the former only penetrated by nerves. Detached swim bladder extensions (D-G) display the gas-filled portion and parts of the pad shown in lateral (D), anterior (E), antero-medial (F) and ventro-medial (G) views. Black (C) and white (D-G) asterisks indicate the gas-filled part of the anterior most swim bladder extension contacting the lagena. asc, anterior semicircular canal; hsc, horizontal semicircular canal; lag, lagena; lago, lagenar otolith; N, nerves (PLLN, X, and/or IX); OT, optic tectum; PLLN, posterior lateral line nerve; psc, posterior semicircular canal; sb pad, swim bladder pad; saco, saccular otolith; (?)IX, glossopharyngeal nerve; (?)X, vagal nerve. Scale bars, 1 mm.