4: Parenchymal oxydiact with central knot; 5: Oxydiact with terminal barbs and four central pointed knobs, cruciately disposed; 6: Marginal oxydiact with four cruciately disposed central knobs.
Schulze, F.E. 1887a. Report on the Hexactinellida collected by H.M.S. ‘Challenger’ during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. ‘Challenger’, 1873-1876. Zoology 21 (Text): 1-514
Photographer: F.E.Schulze. Publisher: Dagaeff, Anne-Cecile.