Urceolaria Stein, 1854 (ref. ID; 2014) or Lamarck (ref. ID; 1618)
Class Oligohymenophora: Subclass Peritricha: Order Peritrichida: Suborder Mobilina (ref. ID; 2014)

[ref. ID; 2014]
The body viewed laterally varies from cylindrical to subconical in shape. The anterior half bearing the peristome, is often displaced to one side. The peristomial ciliary wreath (membranelles) always complete a full circle and sometimes more (360-400 degrees). The aboral disc is typically suctorial and the elements or denticles consists of smooth overlapping units which never possess centrifugal processes or centripedal rays. There are 2 freshwater species, one is found on fishes the other on planarians. The genus may be most easily confused with Trichodina whose wreath also winds through 360-400 degrees. However, in the latter the denticles possess both centrifugal processes and centripedal rays.
Quote; Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014)

Urceolaria karyolobia Hirshfield, 1949 (ref. ID; 1618)
Description; Macronucleus lobate and conspicuous; in the mantle cavity of limpets, Lottia gigantea and Acmaea spp. (ref. ID; 1618)
Measurements; 45-50 um in diameter, 20-30 um high. (ref. ID; 1618)
Urceolaria mitra (Siebold) (ref. ID; 1618)
Description; On planarians. (ref. ID; 1618)
Measurements; 80-140 um long. (ref. ID; 1618)
Urceolaria paradoxa Claparede & Lachmann (ref. ID; 1618) reported author and year? (ref. ID; 191)
Description; Colonial forms; in the respiratory cavity of Cyclostoma elegans. (ref. ID; 1618)
Measurements; 70-80 um in diameter. (ref. ID; 1618)