Figure 1. Schematic drawings of the membranous labyrinths of a surface fish of Poecilia mexicana from Río Oxolotán.

(A), right labyrinth with semicircular canals and end organs with otoliths shown in shaded gray and maculae shown in red in lateral view (A₁) and in medial view (A₂). (B), left and right end organs in dorsal view displaying the position of end organs with respect to the main axis of the fish. d, dorsal; L, lagena; la, lateral; r, rostral; S, saccule; U, utricle. Scale bar = 1 mm.