The lizard ear: Scincidae

Observations on inner ear structure were made in five species of Scincidae, together with measurements of auditory sensitivity in terms of cochlear potentials. The basilar membrane and auditory papilla show a characteristic form, with considerable uniformity in dimensions except for a moderate expansion in the dorsal region and a more prominent one at the ventral end. A characteristic feature is the presence of a tectorial membrane that covers a large part of the surface of the medial limbus, but never leaves this surface and thus fails to make any contact with the auditory papilla. Hair‐cell stimulation is achieved entirely through operation of the inertia principle (or equivalent principles) by means of a chain of sallets extending along most of the cochlea but giving way in the region of the ventral expansion to a single large body, the culmen papillae. The sensitivity varies in the five skinks studied from better than average to some‐what below average in comparison with other lizard species. Thus an inertial (or inertia‐like) system of hair‐cell stimulation compares favorably with the tectorial membrane (restraint) system exhibited in the ears of most other lizards and all the higher animals.