Ontogeny of the hyopalatine arch, jaws, and opercular series of Megalechis thoracata (MTD-F 40168, cleared and double stained). A 5.3 mm SL. B 6.5 mm SL. C 9.5 mm SL. D. 22.0 mm SL; distal tip of maxillary barbel cartilage not shown. Abbreviations: An-Ra, angulo-articular-retroarticular; Apa, autopalatine;; De, dentary; Hy, hyomandibular; HyQC, hyomandibulo-palatoquadrate cartilage; Iop, interopercle; MaBC, cartilage of Mandibular barbel; MC, Meckel’s cartilage; Met, metapterygoid; Mx, maxilla; MxBC, cartilage of maxillary barbel; Op, opercle; PAp, pars autopalatina; PMet, pars metapterygoidea; Pmx, premaxilla; Pop, preopercle; PQ, pars quadrata; Q, quadrate.