Tail-like appendages are found in Scaphiodon and in Dysteria and its allies (Gymnostomaceae), Urocentrum (Aspirotrichaceae), Discomorpha and Caenomorpha (Heterotrichaceae). In the first two and last two cases they are prolongations of the body; in the third an aggregate of cilia. One or more long caudal setiform cilia are present in the genera Lembadion, Pleuronema, Cyclidium, Lembus, Cinetochilum, Ancistrum, and Uronema; all these are addicted to making springing darts. Tufts of cilia of exceptional character often serve for temporary attachment. The stalk (or at least its external tube) of the Peritrichaceae appears to be the chitinous excretion of a zone of such cilia. Fauré-Fremiet terms such a zone or annular brush a "scopula" ("Struct. de l'app. fixateur chez les Vorticellides," Arch. Protist. vi. 1905, p. 207). For a discussion of the finer structure of the cilia in Ciliata, and the mechanism of their action, see Schuberg, Arch. Protist. vi. 1905, p. 61.
See Mitrophanow "Sur les Trichocystes ... du Paramoecium," Arch. Protist. v. 1904, p. 78.
The "neurophane" fibrils of Neresheimer, Arch. Protist. ii. 1903, p. 305 f.
Sometimes the number of afferent canals is limited to five (Paramecium), or even one. There may be one or more contractile vacuoles, and in the latter case the different ones have an independent rhythm.
It is from such conclusive cases that the universal character of a discharge to the surface has been inferred in the rest of Protista possessing this organ.