Fig. 4 in Eocene phymaraphiniid demosponges from South Western Australia: filling the gap

Fig. 4. Skeletal features of the phymaraphiniid sponge Twertupia subglabra (Chapmann and Crespin, 1934), from the Fitzgerald River National Park (A, B, F, H, Doyle Road; C, D, E, G, I, Hamersley River area), Australia, upper Eocene. A. Upper surface showing ectosomal disco/phyllotriaenes; between them rhizoclone-like modified desmas are visible, ZPAL Pf. 14/st.A822. B. General view of the choanosomal skeleton with canal openings, ZPAL Pf. 14/ st.A819. C. Detailed view of choanosomal skeleton surface showing trider desmas and their sculpture in oblique view, ZPAL Pf. 14/st.906. D. Surface of choanosomal skeleton showing development of the secondary skeleton composed of flattened modified triders covering canal openings, ZPAL Pf. 14/ st.906. E. Young trider desma partly incorporated into the skeleton, ZPAL Pf. 14/st.A743. F. Surface of choanosomal skeleton showing variable sculpturing of the triders, ZPAL Pf. 14/st.A819. G. Details of trider sculpture and articulations, ZPAL Pf. 14/st.906. H, I. Trider sculpture variability. H. ZPAL Pf. 14/st.A748. I. ZPAL Pf. 14/st.A821.