There have been relatively few studies concerning the auditory capacities of the lizard. Because of its intermediate structural complexity, however, the saurian ear offers the opportunity for a number of interesting comparisons with the more highly developed avian and mammalian ears. The present paper describes the results of several investigations in this area performed at the Auditory Research Laboratory, Princeton University. 14 species representing 6 families were studied. Inner-ear potentials, recorded from the round-window membrane, were used as an index of hearing. In relation to the mammalian ear, these ears were generally found to (a) be rather insensitive within a narrow frequency range, (b) have a very narrow dynamic range, and (c) be nonlinear at even low stimulus intensities. It was found, however, that the best individuals of a few species rivaled the sensitivity of mammalian ears in the middle frequencies. The role of the middle-ear mechanisms in sound conduction and sound control was also studied.