hymenostomata

Century Dictionary and Cyclopedia

1. A suborder of holotrichous Ciliata, in which the mouth is usually situated at the bottom of an elongated, gutter-like, peristomial depression and opens into a short esophageal tube which is never supported by a palisade of rods. In many, perhaps all, forms there is a small undulating membrane at the margin of the mouth. The families included are Chilifera, Microthoracina, Paramœcina, Urocentrina, Pleuronemina, Isotrichina, and Opalinina, found mostly in infusions, though the last two are parasitic. Delage.