Family: Apex somewhat to much fan-shaped; oral region along apex, may extend ventrally (Illustrated Guide, 1985). Cytostome slit-like, situated apically on non-ciliated ridge of the body (Carey, 1992).
Genus: Body long to ovoid; apex fan-shaped; txicysts evenly distributed along edge of apex (Illustrated Guide, 1985). Body elongate, circular in cross section; antrerior obliquely truncated, surmounted by an unciliated apical ridge, which is lined with trichocysts; cytostome slit-like (Carey, 1992).

S. syrtis	Spathidium sp.	Spathidium sp. ? posterior tapered