Genus: Ovoid to elongate; dorsal surface has reduced somatic ciliation; ventral with well developed kineties; peristome apical, 1/3 of the body length; buccal ciliation massively developed; a single macronucleus (Carey, 1992). Peristome leads directly into cytostome; covex left side not ciliated ?, but bears bristles; flat right side ? with 3-5 ciliary rows; perstome begins at pointed anterior end, 1/3 of the body length; macronucleus simple; contractile vacuole subterminal (Kudo, 1966). Species:

50 μm 100 μm 150 μm; x 400

31 μm 63 μm 94 μm; x 640

Protocruzia pigerrima (Cohn, 1866) da Cunha, 1914: Very small, 20 μm long; similar in form to P. adherens (Carey, 1992). 20 μm (da Cunha), 50-60 μm long; peristome 1/4 - 1/3 the body length (Kudo, 1966).

* Protocruzia adherens (Mansfeld, 1923) Kahl, 1930-5: Ovoid, 60 μm long; buccal region conspicuous starting at the apex of the cell and occupies at least 1/4 of the body length (Carey, 1992).