FIG. 9. — Acritolepis ushakovi n. gen., n in Devonian acanthodians from Severnaya Zemlya Archipelago (Russia)

FIG. 9. — Acritolepis ushakovi n. gen., n. sp., histologic structure of separated elements, Severnaya Zemlya Formation; A, vertical section through the tectal plate with starlet-like stellate tubercles (LIG 35-2136), (see Fig 7H), thin section 3499; B, magnified area of the same plate, microstructure of the central tubercle; A, B, paratype LIG 35-A-390, Spokojnaya River, outcrop 41, bed 12; C, trabecular dentine of the palatine tooth (see Fig. 5A), thin section 3501; D, vertical longitudinal section through the denticled tessera-scale of one-sided areal growth (see Fig. 5C), anterior to right, thin section 3500; C, D, paratype LIG 35-A-386, Matusevich River, outcrop 1, bed 21. Abbreviations: abo, acellular bone; cbo, cellular bone; cvc, circular vascular canal; dt, dentine tubule; dto, denteon; gl1, gl2, gl3, lamella of areal growth; lac, lacuna; md, mesodentine; oc, osteocyte cavity; os, osteon; trd, trabecular dentine; vc, vascular canal. Scale bars: 0.1 mm.