endostome

noun

(Gr. endo: within; stoma: mouth) The inner row of teeth of a peristome; the inner circle of a diplolepidous peristome, formed from contiguous periclinal wall-pairs of the primary and inner peristomial layers; typically a weak membranous structure consisting of a basal membrane bearing segments and cilia. The endostome is homologous with the haplolepidous peristome.