Elongate Halcampidae, not divisible into regions. Aboral end physa-like, perforated by pores. Column smooth, without cuticle or tenaculi, with spirocysts, and longitudinal muscles in the region of the sphincter. Sphincter weak, extending into the bases of the tentacles. Tentacles 10, their longitudinal muscles well developed and ectodermal. A weak, ventral siphonoglyph. 10 pairs of mesenteries, 8 mesenteries arranged as the macrocnemes in Edwardsia, and the fifth couple are perfect and fertile, the other mesenteries sterile. More mesenteries than tentacles. Retractors restricted, more or less kidney-like. Parietal muscles well developed, recalling the longitudinal muscles of the microcnemes. Ciliated tracts of the filaments discontinuous. Cnidom: spirocysts, basitrichs, microbasic p-mastigophors.
P. antarctica Carlgren 1927
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1