The amphisbaenian ear: Blanus cinereus and Diplometopon zarudnyi.

Observations on the structure and function of the ear in amphisbaenians have been extended to two new species: to Blanus cinereus of the family Amphisbaenidae and Diplometopon zarudnyi of the family Trogonophidae. Blanus, considered one of the most primitive of this group of reptiles, shows a distinctive form of sound-receptive mechanism. The usual extracolumella is lacking, and the columella attaches to a cartilaginous plate beneath the skin posterior to the facial area. Diplometopon zarudnyi, a highly modified trogonophid, shows a columella and extracolumella of massive dimensions, with considerable calcification of the latter process. Cochlear potential measurements revealed the levels of auditory sensitivity in these species. A peculiar feature is the degree of stability of the ear's responses in the presence of large variations in body temperature.