Acaudina

Clark, 1907

7 species

Tentacles 15, with only 2 small digits. Body cylindrical stout, not having a caudal portion and not tapering posteriorly. Radial pieces of calcareous ring with very conspicuous, bifurcated, posterior prolongations. Calcareous deposits in the form of thick plates, with few, small perforations and a number of conspicuous sharp projections. Phosphatic deposits wanting. (Clark, 1907)

Tentacles with only one pair of lateral digits. Tail practically absent, inconspicuous. Ossicles smooth or spinose thick plates, often doughnut-shaped with one or more perforations. Ossicles usually absent from the body wall, but often found close to the posterior end of the body. (Pawson & Liao, 1992)