Fig. 2

Head structures of Srokalarva berthei and some derived artifacts. a, Unpolarized, reflected light. b, An interpretative version of (a). c and e, Low angle unpolarized light, from multiple source directions. d and f, Interpretative versions of C and E. g, Red–cyan stereo anaglyph under cross-polarized light. (For best visual results, use red–cyan glasses for viewing.) h, Interpretative version of (g). Note how the mandible shape depends on variation in lighting. Only the stereo anaglyph provides a neutral evaluation of head structure. Abbreviations: an, antenna; “ce”, presumptive compound eye; cl, clypeus; hp?, possible hypopharynx of the intercalary segment; lb, labium; “lr”, labrum interpreted by Kukalová-Peck [5]; lr, labrum interpreted by us; “md”, mandible interpreted by Kukalová-Peck (1997); md, mandible interpreted by us; mx, maxilla; su, suture, possibly the epicranial suture