Fig. 19. Oral area of the rhombiferid Rhombifera bohemica Barrande, 1867, repository unknown, Late Ordovician, Czech Republic, showing interpretation of oral plating. A1, latex cast of oral area; A2, the same with interpretation of oral plating superimposed; A3, interpretation of oral plating. An, position of anus; H, position of supposed hydropore; M, mouth; O1–O6, first oral plates; R1–R5, radial plates, which bear the ambulacral facets. R3 supports facet for ambulacrum A, R4 ambulacrum B, etc. clockwise around the mouth. Early glyptocystitoids had six radials. In the Rhombiferidae Kesling, 1962, there are only five; R6 is missing. Photograph from Kesling 1962: pl. 2, fig. 1, right.