Ossicular chain is massive, nearly straight and loosely joined. Stapes is remarkable in being columnar. No conventional mammalian, stirrup like crura. This implies it is nearly one third of manatee facial. Malleus is thick ovoid with ventrolateral manubrial flange Large tensor tympani muscle inserts on a small lat malleal pedicle.
Vestisbular stem seem poorly developed and small.
There is no outer osseus spiral lamina. Little base to aspex differentiation. At thickest basal point, membrane is 200u wide and 7 u thick. Apically membrane is 600 u and 5 u thick. Manatees expected to have a center freq similar to humans but narrower in overall srange.