Fig. 2.

Fine folds on ventral protegulum and ridges on ventral brephic shell of Eohadrotreta? zhujiahensis and Eohadrotreta zhenbaensis. a enlarged protegulum of E.? zhujiahensis, showing three pairs of fine folds by arrows. b-h E. zhenbaensis; (b) a pair of thin folds (arrows) on a lager specimen; (c-d) fine folds on ventral protegulum; (c) lateral view, showing thin folds by arrows and densely packed ridges by tailed arrows; (d), show four pairs of folds by arrows; (e) conjunct valves, show the fine folds of ventral protegulum by arrows; (f) enlarged view, noting the thin fold covered by the above pitting structures; (g) enlarged view of (e); (h) enlargement of the ridges (tailed arrows) covered by the pitting structures on the posterior margin of brephic shell. Abbreviations: al, anterior lobe; c, shallow cleft; f, pedicle foramen; ll, lateral lobe; pr, protegulum. Scale bars: a-e, 20 μm; f, 2 μm; g, 10 μm; h, 5 μm