| Contents | Classes | Subclasses | Orders | Suborders | Families |
Family LOXOCEPHALIDAE Jankowski, 1964
| Syn. | Cardiostomatellidae |
Body elongate-ovoid, generally uniformly ciliated, with caudal cilium or cilia and (in some genera) naked apical end; pronounced parateny near anterior end; clearcut postoral suture replacing director-meridian in some species; buccal cavity small, anteroventral, with ciliature reminiscent of Tetrahymena; common polysaprobic forms in fresh-water (occasionally brackish) habitats.
| Dexiotricha Stokes, 1885. Several species. |
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| Loxocephalus Eberhard, 1862. Several species. |
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| Paradexiotricha Grolière, 1975. Single species. |
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| Paratetrahymena Thompson, 1963. Single species. |
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| Incertae sedis: | |
| Cardiostomatella Corliss, 1960 (for Cardiostoma). Few spp. |
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