Figs 11-14. Besa papillaeformis, topotype material (Setchell #6485, UC173490). Longitudinal sections through vegetative thallus; note abundant formation of secondary pit connections. Lower cells of upright are elongated, central medullary cells are loosely compact and slightly radiating thallus outward, small-celled cortical zone is composed of longitudinally concavo-convex divided surface cells.