. Bulletin of the Natural History Museum Zoology. ANATOMY OF THE MELANONIDAE 15. Fig. 3. Infraorbital bones of M. zugmayeri in specimens of: A, 66mm SL; B, 100mm SL and C, 130mm SL. posteriorly, the body of the bone is expanded. The fifth infraorbital has a long orbital margin, the lower part of which projects anteroventrally in front of both the third and fourth to which it is connected by strong connective tissue; it has a narrow flange along its upper orbital border. The sixth (dermosphenotic) is as large as the fifth and has a pronounced orbital curvature which brings its anterior tip to t
. Bulletin of the Natural History Museum Zoology. ANATOMY OF THE MELANONIDAE 15. Fig. 3. Infraorbital bones of M. zugmayeri in specimens of: A, 66mm SL; B, 100mm SL and C, 130mm SL. posteriorly, the body of the bone is expanded. The fifth infraorbital has a long orbital margin, the lower part of which projects anteroventrally in front of both the third and fourth to which it is connected by strong connective tissue; it has a narrow flange along its upper orbital border. The sixth (dermosphenotic) is as large as the fifth and has a pronounced orbital curvature which brings its anterior tip to the same vertical plane as the ascending process of the first infraor- bital. In the two smaller specimens of M. zugmayeri examined, the dorsolateral flange remains undeveloped on the first, fifth and sixth infraorbitals of the 66mm specimens and the ascending process of the first infraorbital is inclined anteriorly in both (Fig. 3A). The anteroventral border of the fifth infraorbital is less pronounced and in the 100mm SL speci- men its tip lies medial to the rim of the fourth infraorbital; the sixth lacks the anterior elongation of the larger (130mm SL) specimen (Figs 3B, C). Unlike other gadiforms where the posterior (fifth and sixth) infraorbitals are shallow, those of Melanonus are as deep as the anterior ones. The anterior curvature of the upper infraorbital (dermosphenotic) is more reminiscent of some macrouroids (see below) than gadoids. The central position of the ascending process of the first infraorbital is probably a plesiomorphic gadiform feature (on the basis of commonality) as is the reduced size of the second infraor- bital. The extension of the lower part of the fifth infraorbital and the enlargement of the dermosphenotic are, because of their restricted distributions, taken to be derived features. According to Iwamoto (1989) among macrouroids, exclusion of the third and fourth infraorbitals from the orbit is a derived condition. In Melanonus similar exclusion
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