The recording I have does not sound like the score (of the opera) looks where this is supposed to be. Does the stand alone D of the H have a part that is different from the opera?
http://imslp.org/wiki/La_Gioconda_(Ponchielli,_Amilcare) The whole score is here, so if you know which act in which to look, this should answer your question. I have only played Dance of the Hours on its own, so I can’t answer your question off the top of my head.
It’s on page 382 of Act 3. The Dance of the Hours has various sections: The Hour of the Dawn, Dance of the Hours of Daytime, Dance of the Hours of the Evening, and Dance of the Hours of Night. It looks exactly the same as the one that we play as a stand-alone piece in symphony concerts. This is the piece made famous in the first Fantasia by Walt Disney, with the dancing hippos and crocodiles.