Psychropotidae

Théel, 1882

4 genera, 1 monotypic; 31 species

Body elongate, sometimes very depressed, often with a large dorsal appendage. Skin thick, gelatinous. A marginal fringe of appendages around the ventral surface of the body. No non-retractile lateral papillae. Tentacles large, with a broad disc. Tube feet usually present also in the mid-ventral ambulacrum. Calcareous deposits pointed rods or derivatives of such, not arranged longitudinally in the dorsal papillae. Calcareous ring incompletely developed. Gonads of various forms, simple tubes or large branched organs. Mesentery a continuous membrane, well developed on the second loop. (Mortensen, 1927)

Tentacles 10-18. Brim of tube feet surrounding the body. Mid-ventral tube feet present. Deposits cross shaped or rod shaped. Calcareous ring absent, or consisting of a diffuse network. (Hansen, 1975)