(Anatidae; Ϯ Masked Duck N. dominicus) Gr. νομος nomos  customary, established  < νεμω nemō  to distribute; ονυξ onux, ονυχος onukhos  nail; "NOMONYX, gen. nov.  CH.- Similar to Erismatura, but differing from all the species of that genus in the form of the maxillary unguis, which is similar to that of Fulix and allied genera, the same being in Erismatura the most peculiar and important generic character.  Type, Anas dominica, Linn.  Altogether the most distinctive feature of the genus Erismatura consists in the remarkably peculiar conformation of the maxillary unguis, or nail of the upper mandible. This, viewed from above, is extremely small, narrow, and linear, the broader terminal half being bent very abruptly downward and backward, so as to be visible only from in front or below.  ...  Anas dominica, Linn., has the nail of normal form, or very much like that prevailing among the ducks generally, and on this account should be separated generically from Erismatura." (Ridgway 1880).
Var. Namonyx, Momonyx.

Search for more names on the Key to Scientific Names in Ornithology by James A. Jobling.
Recommended citation
Jobling, J. A. (2018). Key to Scientific Names in Ornithology. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2018). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 19 December 2018).