Siniotrochus

Pawson, 1971b

3 species

Approximately 10 tentacles. Calcareous ring is solid apparently directed ventrally. Dorsal body wall coriaceous due to a single layer of wheels. Wheels are concave, circular to oval, 0.42 mm in average diameter. Rim with average of 18 blunt spines projecting outward, an average of 40 broad blunt spines projecting inwards, and an average of 17 spokes radiate from a wide hub. There are 4-15 angular perforations in the hub. Wheels are closely aggregated anteriorly and posteriorly less so between. Ventral body wall with far fewer deposits than dorsal. Calcareous ossicles exclusively wheels of this one type; with the concave surface facing outwards. Consistent perforations in the hub are the most conspicuous feature of this genus. (Pawson, 1971b)