Details of late pre-normal valve of Ulnaria ulnabiseriata from Fig. 9G, internal view, SEM A, B middle parts of valve, note a row of poroids located at midline (A, double-headed arrow) and a row of serrated projections aligned with each virga (B, three arrows) C–F apical details, note the closed two apices of valvocopula (D, F, arrow respectively). Scale bars: 6 μm (A, C); 3 μm (B, D–F).