An examination of serial sections of the ears of several specimens of Chamaeleo senegalensis and Chamaeleo quilensis gives support to an earlier suggestion that these ears function by means of a substitute round window. The usual type of round window is absent, but there is a tortuous pathway leading from the scala tympani through the perilymphatic recess and then along the foramen of the glossopharyngeal nerve to the air cavity of the middle ear. This pathway makes possible a mobilization of the cochlear fluids in response to sound pressures exerted at the oval window by the columellar footplate. However, the mechanism is somewhat inefficient; the frictional resistance along the pathway reduces the amplitude of cochlear motion. The relatively poor sensitivity of these chameleon ears is thus largely accounted for. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company
