Halcampoididae with elongate body divisible into physa, scapus and scapulus. Scapus with tenaculi. No sphincter. Tentacles 20, their longitudinal muscles ectodermal. Radial muscles of oral disc ectodermal. A single, ventral siphonoglyph. Mesenteries 10 pairs of which 5 pairs are macrocnemes, the eight "Edwardsia"-mesenteries + one couple) pairing with the dorsolateral protocnemes. The sixth primary ventrolateral couple is represented by two perfect but weak mesenteries without retractors. Four pairs of microcnemes in the dorsolateral and lateral exocoels, only present in the distal part of the body. Retractors of the perfect mesenteries strong, reniform, parietal muscles rather well developed. Filament present only on the 10 stronger mesenteries. Cnidom: spirocysts, basitrichs, microbasic p-mastigophors.
P. californica Carlgren 1900
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1