Fig. 3

Species of Hymenaster. a Deep-sea photograph of living Hymenaster ex gr. perissonotus Fisher, 1911. Note the elongated actinolateral spines in membrane, and centrally placed osculum. b, f, g Hymenaster perissonotus Fisher, 1911. b, g Denuded abactinal surface of individual to show open trellis construction of abactinals. F Drawing of actinal aspect of interradius, denuded, to show two chevron ossicles and processes from the adambulacrals contacting the abactinals. c–e, Hymenaster pellucidus Thomsen 1873. c Denuded abactinal surface, d, actinal surface. e Drawing of abactinal surface to show two rows of abactinals on each side of the radius, and absence of radials; the interradial row is labelled as adra, the other as adrb. Primary interradials beige, primary radials/radials mauve, chevrons green, interradial row of abactinals pink (compare with Fig. 4). Ad, adambulacral ossicles. Scale bars in millimetres