Viscerocranium of Discotrema crinophilum (ROM 85350, 25.4 mm SL mm SL). A Hyopalatine arch and opercular series (right side) in lateral view (image reversed), outline of preopercle, opercle, and subopercle highlighted by thin black line, posterior process of hyomandibular indicted by black asterisk (*); B articulation between hyomandibular and pterotic (left side) in ventral view, ligament between posterior process of hyomandibular (*) and hyomandibular process of pterotic indicted by double arrow head; C close-up of posterior teeth on premaxilla (left side) in lateral view; D lower gill-arch elements in dorsal view; E upper gill-arch elements (right side) in dorsal view; F close-up of PbTP3 (right side) in ventral view (image reversed); G close-up of Cb5 (right side) in dorsal view; H close up of gill rakers on posterior edge of ceratobranchials 1 and 2 (right side) in dorsal view; I hyoid bar (left side) in lateral view and urohyal. Abbreviations: AC, acrodin cap; ACh, anterior ceratohyal; Ana, angulo-articular; Apa, autopalatine; Bb2–4, basibranchial 2–4; Bh, basihyal; BR, branchiostegal rays; Cb1–5, ceratobranchial 1–5; CoPr, coronoid process; DHh, dorsal hypohyal; Dn, dentary; Eb1–4, epibranchial 1–4; Ect, ectopterygoid; GR, gill rakers; Hb1–3, hypobranchial 1–3; Hy, hyomandibular; Ih, interhyal; Iop, interopercle; MC, meckel’s cartilage; Mx, maxilla; Op, opercle; PbTP3, pharyngobranchial 3 toothplate; PCh, posterior ceratohyal; Pmx, premaxilla; Pop, preopercle; Pte, pterotic; Q, quadrate; Ra, retroarticular; RT, replacement teeth; Sph, sphenotic; Sop, subopercle; Sym, symplectic; Ur, urohyal.