1911 Encyclopædia Britannica/Ciliata

CILIATA (M. Pertz), one of the two divisions of Infusoria, characterized by the permanent possession of cilia or organs derived from these (cirrhi, membranelles, &c..), and possessing a single mouth (except in the Opalinopsidae, all parasitic). They are the most highly differentiated among the Protozoa.