Pachythyone

Deichmann, 1941

3 species

Small forms a few cm long with stout cylindrical feet in 5 longitudinal bands and scattered in the interambulacra; dorsally and toward the ends more papilliform. Ventral tentacles smaller. Calcareous ring with short posterior prolongations. Single stone canal. Single Polian vesicle. Gonads forming two tufts of few tubules. Spicules, an inner layer of oval buttons or plates with the external side covered by a dense reticulum; an inner layer of oblong 4 holed buttons regularly knobbed. Feet with end plate, reduced in the papilliform feet. Walls supported by tables with numerous rods in the reticulated spire; a few developed as plates. Introvert with oblong tables; tentacles with heavy perforated plates which gradually become smaller and more delicate in the branches. (Deichmann, 1941)

Small forms. Feet in bands in the radii, numerous also in the interradii. In the surface of the skin there are plates whose upper side is covered with a thick network. Deeper in the skin there are elongate plates with 4 perforations and regularly places bumps. The feet have a well developed end plate which is diminished in the papillae shaped appendages of the back; in the feet walls there are tables with many columns in a net shaped top construction. The introvert has elongated tables. In the tentacles there are strong network plates. (Panning, 1949)