Haeckel
Radial tubes inflated ovate to spindle-shaped, becoming very thin proximally, with inflated terminal knob with 2 (often a few with 3 or 4) divergent, inwardly curved, hollow, terminal branches. Whorl of 4 (often 5 or 6, more rarely 2 or 3) irregularly crossed lateral branches, at about two thirds distance from proximal end, with spathillae of 4-6 curved teeth, sometimes also with a central tooth. Length of tubes: 1.5-2.5 mm.