External and internal views of Scolanthus armatus (NSMT-Co 1609). External views (A, B) and internal histological sections (C–I). A Whole living specimen of S. armatus. The periderm of aboral end was stripped off while the sampling B enlarged view of most distal part C longitudinal section of oral end D longitudinal section of a tentacle E transverse section of a tentacle F transverse section of actinopharynx of the longitudinal half of body G transverse section of mesentery H transverse section of filaments I longitudinal section of aboral end. Nemathybomes distributed up to the tip of aboral end. Abbreviations: a, actinopharynx; Ne, nemathybome; pm, parietal muscle; rm, retractor muscle; Te, tentacle; tlm, tentacular longitudinal muscle; Ts, testis. Scale bars: 5 mm (A); 1 mm (B); 500 µm (C, F, H, I); 100 µm (D, E, G).