Articulation of the tentorial transverse bar to the head capsule in the Polydesmida A–C head in lateral view (anterior is left), volume rendering D–F head, sagittal section through tentorial transverse bar, volume rendering A, D, G Oxidus gracilis B, E, H Coromus vittatus C, F, I Tymbodesmus sp. J Polydesmus angustus G–J optical cross sections K, L the Tömösváry organ in Eurydesmus laxus after Hennings (1906): K cross-section, modified from Hennings (1906, plate XXXI, fig. 11) L head in lateral view, modified from Hennings (1906, plate XXXI, fig. 9). Abbreviations: at = antenna, co = collum, gls = gnathal lobe sclerite, hc = head capsule, la = labrum, mc = mandibular cardo, ms = mandibular stipes, tb = transverse bar of tentorium, pp = posterior process of tentorium. Asterisk (*) indicates the structure previously interpreted by Hennings (1906) as Tömösváry organ. In the volume renderings the tentorium is marked with a red dotted line. Arrows indicate the flexible connection of transverse bar and head capsule. Scale bars: 100 µm (G–J).