(syn. Tockus Ϯ Southern Yellow-billed Hornbill T. leucomelas) Gr. ξανθος xanthos yellow; ῥυγχος rhunkhos bill; "Xanthorhynchus gen. nov., type Buceros leucomelas Licht.: bill very long, conspicuously and evenly arching, normally not toothed, though sometimes slightly chipped; length of the culmen about two and a half times the height at the nostrils; casque forming a high ridge, evenly arching with the bill, from which it is marked off by a shallow groove extending to a point not far from the tip; wing and tail of about the same length; secondaries as long as the primaries." (A. Roberts 1922).