The Collaborative International Dictionary of English v.0.48:

Desmognathous \Des*mog"na*thous\, a. [Gr. desmo`s bond + gna`qos
   jaw.] (Zool.)
   Having the maxillo-palatine bones united; -- applied to a
   group of carinate birds (Desmognath[ae]), including various
   wading and swimming birds, as the ducks and herons, and also
   raptorial and other kinds.
   [1913 Webster]