Protankyra Östergren, 1898

Diagnosis (after Clark 1908). Tentacles digitate, 10–12, rarely 13 or 14; digits two on each side (rarely one only). Cartilaginous ring wanting. Polian vesicles 2–10, rarely one only. Stone canal usually single, rarely several. Stock of anchors more or less branched or only finely toothed; arms usually serrate; vertex of anchors without knobs. Anchor plates without a handle; with numerous irregular perforations, never with two large central perforations; with a more or less imperfectly developed bow across outer surface of posterior end; plates and perforations with either smooth or dentate margins.

Remarks. We have added “never with two large central perforations” to the diagnosis of anchor plates to distinguish Protankyra from genus Rynkatorpa Rowe & Pawson, 1967 .