FIG. 11. Internal anatomy of Actinostella digitata (McMurrich, 1893). A, longitudinal section of the distal column showing distal vesicles (ve) in the marginal ruff, marginal sphincter muscle (s), and the fosse; B, cross section proximal to the actinopharynx level showing cycles of mesenteries, and the siphonoglyph (si); numbers between pairs of mesenteries indicate the corresponding cycle; C, detail of verrucae (v) in distal column; D, cross section of a tentacle showing ectodermal longitudinal muscles; E, detail of developing spermatic cysts (sc); F, detail of a cross section showing the retractor (r) and parietobasilar (p) muscles; G, cross section of proximal end showing weak basilar muscles (b). Abbreviations: b, basilar muscles; ep, epidermis; ga, gastrodermis; me, mesoglea; sc, spermatic cysts; p, parietobasilar muscle; r, retractor muscle; s, sphincter; si, siphonoglyph; t, tentacle; v, verrucae; ve, vesicles. Scale bars: A, F, 5mm; B–E, G, 1 mm.